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• Development of Visualization Technology for Building Energy Information Based on IndoorGML Development of Visualization Technology for Building Energy Information Based on IndoorGML ▲ Research Fellow Choi Hyun-sang, Department of Future & Smart Construction Research, KICT Prologue In the representation of indoor spaces used in the construction of indoor spatial information, international standards such as IFC (Industrial Foundation Classes), CityGML (City Geographic Markup Language), and IndoorGML (Indoor Geographic Markup Language) can be applied. There are two ways to construct indoor space data using these standards: the first is a direct construction method using authoring programs, which allows for detailed representation but involves a significant amount of time and cost. The second method involves creating data by converting data that are already standard or are used in practice, which is effective in reducing time and cost. Thus, this study aimed at developing a Revit Plug-In based on BIM to extract core indoor spatial information object from sample models, convert them to IndoorGML and integrate them with data visualization technology to develop the supporting technology for the utilization of indoor spatial information. Theoretical Considerations of IndoorGML IndoorGML is a data model for expressing and exchanging indoor spatial information, which was developed by the Open Geospatial Consortium (OGC), an international standardization organization for spatial information. It is a data standard in GML format based on XML (eXtensible Markup Language) schema. IndoorGML was developed to support the requirements for indoor spatial data services, and is defined based on a cell space model. IndoorGML focuses on the expression of the geometric relationships and topology (topological relationships) information of indoor spaces, rather than the detailed representation of indoor objects such as building components or furniture. In IndoorGML, the smallest and most basic spatial unit that constitutes a building is called a cell space, and a building is considered a series of cell spaces. To represent this cell space model in detail, IndoorGML defines the following four items: Cell Geometry Topological Relationship between Cells Meaning of the Cell Multi-Layer Spatial Model Based on the four definitions mentioned above, IndoorGML can ① represent the characteristics of indoor spaces, and ② provide spatial reference information about the topographic features located within indoor spaces. Figure 1 shows the geometry options provided by IndoorGML. It displays three options for geometric representation in IndoorGML, and the meanings of each option are as follows: Option 1 : (External Reference) Instead of explicitly representing geometry in IndoorGML, it can be expressed solely through external links to objects defined in other datasets, such as CityGML. OOption 2 : (IndoorGML Geometry Information) When including geometric representations for cell spaces in IndoorGML, 3D spaces are represented as GM_Solid, and 2D spaces (walls) are represented as GM_Surface according to the definition in ISO 19107. Openings (e.g. doors, windows, etc.) are also included in this case. OOption 3 : (No Geometry) IndoorGML document does not include geometry information for cell spaces (spaces can be represented solely by Nodes). Geometry Rules for IndoorGML Conversion The geometry rules for the key objects that constitute IndoorGML are based on the modeling rules presented in the SIG3D "Modeling Guide for 3D Objects Part 1: Basics (Rules for Validating GML Geometrics in CityGML)" technical document. Among the regulations in the aforementioned technical document, the implementation rules for representative objects that are most closely related to this study are as follows: gml : LinearRing: The geometry composing the objects that make up the building is comprised of a single polygon boundary, i.e. a LinearRing (Rs) (Figure 2). gml: Polygon: A polygon (S) is represented as a set of planar LinearRings (Rs). gml : MultiSurface: The MultiSurface used to visually represent the surface objects (M) that make up a building is represented as a collection of unstructured polygons (S), i.e., M={S1, S2, Sn}. gml: The geometry of a 3D object is defined as a collection of polygons that are composed of multiple surface objects (Multi-Surface), and errors can occur depending on the composition of the polygons. Table 1 shows examples of correct and incorrect cases when constructing indoor objects. Development of IndoorGML Plug-In Based on Revit Software (1) Design of Revit Data Conversion Process Autodesk's Revit software, which is commonly used to create 3D BIM models, provides a range of 3D modeling features that support accurate input in terms of visualization and geometry, as well as tools to input and manage relationships between constituent objects. In this study, the Room Schedule and Door Schedule functions provided by Revit were used as a basis, and the CellSpace (Node) and Transaction (Edge), which are core objects of IndoorGML, were constructed based on the connection information entered between the spaces during building design. However, if Room/Door Schedule is missing in the initial BIM modeling process or is omitted due to worker error, it must be checked and corrected through a pre-validation process. Figure 3 shows the data conversion process applied in this study. (2) How to Use Revit's Room Objects, and Rules for Handling Virtual Spaces To extract CellSpaces in IndoorGML using Room objects created in Revit, it is necessary to first check whether the Room object has been input into the Revit model. Figure 4 shows that if a Room object has been input, it is displayed on the screen with crosslines, and that even irregular spaces can be configured as Room objects. In the design of typical buildings, only spaces composed of actual structures (walls, columns, floor surfaces, ceiling surfaces, etc.) are represented. However, in IndoorGML, an indoor space information, it is necessary to divide virtual indoor spaces for large spaces such as auditoriums or banquet halls, as well as narrow and long corridors with changing directions. For this purpose, preprocessing of virtual spaces is required before converting to IndoorGML, and setting and modifying rules for processing virtual spaces is necessary. In this study, additional functions were developed based on the features provided by Revit for processing virtual spaces. (3) Main Features and Achievements of Revit SW-based IndoorGML Plug-In In the Revit SW, it is common to create Room and Door Schedules during the BIM modeling process. However, there may be cases in which they are omitted due to human error or spatial constraints, so it is necessary to check them in advance and make corrections as needed. Figure 5 shows a feature provided by Revit that allows the user to check Room Tags and missing information. Then, when converting Revit data to IndoorGML data using the "IndoorGML Exporter" menu, a verification process is also carried out to check for any missing information. Once the verification of the Revit data that serves as the source of IndoorGML is complete, the user can selectively convert only the desired floors or the entire building into a single IndoorGML file. Figures 7 and 8 show examples of the conversion of Main Buildings 1 and 2 of the Korea Institute of Civil Engineering and Building Technology (KICT). (4) Development of IndoorGML-based Building Energy Information Visualization System In this study, we developed a 3D system that can visualize building energy management by assigning representative values for each spatial unit based on measured values by room and location in Main Building 1 of KICT that was investigated through the aforementioned process, as well as values obtained from the survey. Figure 9 shows the process of integrating the results of a user satisfaction survey program for the building, KBOSS, into indoor space units (left), and examples of floor-by-floor visualization (right). Epilogue This study was performed to secure the core technology for integrating and managing detailed energy data for individual building units and occupant satisfaction survey results in a format that is compliant with the international spatial information standards, which is necessary for developing the technology for energy inspections of metropolitan-scale buildings. Through this study, an IndoorGML data authoring tool was developed and applied to store and represent energy-related information investigated for KICT at the minimum space unit (room) level. It is expected that the results can be utilized as a database and operational technology for micro-level building energy inspection information in the future implementation of carbon reduction policies, which are an important part of building energy monitoring and management on a national scale. Department of Future&Smart Construction Research Date2023-02-27 Hit 88
• ISO 19650-based BIM Information Management Framework ISO 19650-based BIM Information Management Framework ▲ Senior Researcher Won Ji-sun, Department of Future & Smart Construction Research, KICT Prologue In this "Digitize or Die" era, digital transformation is recognized as an essential strategy for corporate survival, and is accelerating across all industries. The construction industry is responding to paradigm shifts through the spread of smart construction technologies such as Building Information Modeling (BIM) adoption, construction machine automation, and the activation of Off-Site Construction (OSC). In July of this year, the Ministry of Land, Infrastructure and Transport (MOLIT) announced the "S-Construction 2030” plan, which aims to achieve "digitalization and automation of the entire construction process by 2030." It presents three promotional tasks for achieving this goal: digitalization of the construction industry, advancement of the production systems, and promotion of the smart construction industry. Of these, the detailed plan for realizing the digitalization of the construction industry specifies the organization of the BIM system and the phased expansion of projects subject to mandatory BIM application. Other countries, including the UK, Denmark, and Ireland, have also introduced the concept of digitalization into their existing BIM roadmaps and are redesigning them as national digital transformation strategies or digital twin strategies. BIM is now recognized as an essential strategic tool for digital transformation. Upon examination, it is evident that ISO 19650 is being actively adopted. ISO 19650 is a BIM information management framework that standardizes the process and information requirements for BIM information procurement across the life cycle of a construction project, and was established in 2018. This international standard was developed by adding digital information management concepts to the UK’s BIM standards (BS 1192 series), which was previously used as the global standard during the early phases of BIM adoption. The UK, Europe, and Australia have designated the ISO 19650 original text or translation as their national BIM standard, while countries like Singapore, Hong Kong, and Saudi Arabia are revising their national BIM standards to include ISO 19650. Many countries are now mandating ISO 19650 certification as a prerequisite for bidding on public construction projects or offering incentives, and more companies in Korea are obtaining ISO 19650 certification to demonstrate their global-level BIM information management technology and capabilities. There is a growing trend of the active utilization of ISO 19650 as part of a BIM-based digital transformation policy. Moreover, as a company's ISO 19650 certification and compliance capacity has become a measure of competitiveness, it is necessary to consider the introduction of ISO 19650 at the national level in Korea. Thus, we aim to propose strategies and methods for introducing ISO 19650 in Korea. In this study, we adopted an approach that reflects the key concepts of ISO 19650 in accordance with the situation in Korea. Our research involved three steps. First, we investigated the current status of ISO 19650 adoption in other countries, and derived the key components of the BIM information management framework by examining international standard documents. Second, we analyzed the software, platforms, and other support tools that enable ISO 19650 adoption, and selected the main functions that need to be implemented for practical application. Third, based on the key components of ISO 19650 and the main functions of ISO 19650 support tools, we proposed an ISO 19650 utilization model and suggested ways to introduce it in Korea. Stages 2 and 3 can be understood as a process of scanning multiple buildings from an urban/regional perspective based on appropriate indicators (whole-building level identification), while Stages 4 and 5 can be understood as a process of closely examining the scanned buildings in detail from a building component perspective (system level diagnostics). In this study, we would like to introduce the data-centric checkup technique of building energy performance that corresponds to Stages 2 and 3 in this context. Current Status of ISO 19650 Adoption in Other Countries Generally, national BIM roadmaps utilize BIM maturity models to establish phase-specific goals for BIM adoption levels and situations. Many countries have already been utilizing the BIM maturity model defined in the UK BIM roadmap (British Standards Institution B/555), which was announced in 2011, as a global standard. In the BIM maturity model of the UK, Level 0 is set in an environment centered on documents such as 2D drawings and text, Level 1 is set in an environment where 2D drawings and 3D data files are used concurrently, Level 2 is set in a discipline-specific BIM model environment, and Level 3 is set in an integrated web-based BIM environment that centrally manages data through a single model. The UK is actively utilizing ISO 19650 to attain Level 2, and is preparing a digital transformation roadmap for attaining Level 3. Currently, most countries are in the Level 2 adoption or activation phase. Many countries are in the process of adopting ISO 19650, as shown in Table 1. Thus, the adoption of ISO 19650 is recognized as an essential requirement for attaining BIM Level 2. The ISO 19650-1 established in 2018 presents the maturity levels of digital information management in each phase as a concept of "stage." The types of data, such as 2D, 3D, and BIM, covered in the UK BIM maturity model have been changed to concepts such as structured, unstructured, BIM, and server-based BIM, and the concept of Common Data Environment (CDE) has been subdivided into the file- and model-based CDE forms and the big data-based CDE forms. Digital information management maturity for each phase is divided into three information management stages along the horizontal axis, and is composed of four layers (standard, technology, information, industry) that represent the major information management perspectives along the vertical axis. In terms of information management perspectives according to standards, Stage 1 is defined as information management based on existing national standards for handling structured and unstructured data, Stage 2 as information management based on ISO 19650 standards for handling shared BIM models, and Stage 3 as information management based on future standards for handling server-based BIM models and structured/unstructured big data. The current stage is Stage 2, and to achieve the corresponding level, information management based on ISO 19650-1 and 2 is required. Deriving Key Components of BIM Information Management Framework Through Analysis of ISO 19650 To achieve the goals aligned with the BIM maturity level or digital information management maturity level, it is important to specify the national-level BIM standards that must be complied with at each phase. Specifically, there are BIM guidelines, BIM classification systems, contracts related to information procurement and LOD standards, as well as BIM maturity assessment methodologies. The BIM Information Management Framework is a standardized system that supports workflows and data acquisition to generate, utilize, and manage BIM data in an integrated digital construction environment throughout the construction life cycle. BIM standards related to the BIM Information Management Framework include BIM standard classification, building SMART International's IFC, IDM, IFD, and COBie. ISO 19650 covers processes in the digital collaboration system such as subject-specific information requirements, digital model deliverables, workflows, information management plans, CDE, etc. from the perspective of comprehensive use of these open standards. The currently published ISO 19650 series is as follows: ISO 19650-1(2018) : Concepts and Principles for Information Management Using BIM ISO 19650-2(2018) : Information Management Using BIM in the Delivery Stage ISO 19650-3(2020) : Information Management Using BIM in the Operational Stage ISO 19650-4(2022) : Process and Standards for Information Exchange ISO 19650-5(2020) : Security Management During Information Management Using BIM ( 1 ) ISO 19650-1 (2018): Concepts and Principles for Information Management Using BIM ISO 19650-1 contains the concepts and principles of an information management framework for BIM collaboration throughout the construction life cycle. Information management is defined as "the process of supporting the production and management of information over the entire construction asset life cycle." The key components of the BIM information management framework are: ① specification of information requirements, ② planning for information delivery, and ③ delivery of information, which support a collaborative environment to enable the consistent delivery of information that varies by project, stakeholder, and purpose through a coherent process and delivery system. In the project delivery phase and operational phase, an information procurement plan is established based on the information requirements of the participants and contractors. In addition, it has the flow in which deliverables reflecting this, such as PIM (Project Information Models) and AIM (Asset Information Models), are delivered and approved. For effective information management, the setting of responsibilities, authorities, and scope of work is crucial, and pertinent functions should be assigned during the project and asset management period. The responsibility assignment items must be specified in the contract document (e.g., through a Responsibility Matrix) to ensure that a person with “AIM approval competency” is designated for asset management and a person with the information standard, process, and CDE configuration competency of the project is designated for project delivery. ( 2 ) ISO 19650-2 (2018): Information Management Using BIM in the Delivery Stage ISO 19650-2 sets information requirements during the project execution phase, and defines a collaborative environment and process for lead appointed parties and appointed parties to efficiently produce information. The information entities of the project delivery phase are set as the appointing party, lead appointed party, and appointed party. The information management process as well as function and standard requirements for each entity are presented for each project delivery phase. A total of eight information management functions in the project delivery phase are defined, and the detailed information management processes for each entity are specified in each section of Chapter 5 in ISO 19650-2 (5.1 Evaluation and requirements → 5.2 Bid announcement → 5.3 Bidding participation → 5.4 Contracting → 5.5 Resource mobilization → 5.6 Collaborative information production → 5.7 Information model delivery → 5.8 Project completion). In this study, ISO 19650-1 and 2 were analyzed to identify the key components of the framework, including specifications related to information management entities, requirements, processes, deliverables, and roles, and were divided into seven components as shown in Table 2 (1. Information Requirements, 2. Information Delivery, 3. Information Management Entities and Roles, 4. Workflows, 5. Information Procurement Plan, 6. Information Management Level, and 7. CDE). Deriving Key Functions through Analysis of ISO 19650 Practical Application Support Tools To apply the ISO 19650 component concept in practice, it is necessary to identify the actually implemented functions and interfaces. According to a survey of the software, websites, platforms, and other tools that support ISO 19650, it was found that the Plannerly platform from the United States is a representative tool that faithfully incorporates the ISO 19650 concepts. However, there are many tools, like US BEXEL, that only partially support ISO 19650 concepts, such as information delivery and CDE concepts, and open BIM formats such as IFC, BCF, and COBie. ( 1 ) The US: Plannerly Plannerly is a BIM information management platform that provides integrated support for the appointing party (project owner), designing party (AE), lead appointed party (contractor), and the appointed party (subcontractor) to plan, manage, and validate BIM requirements in one place. It is designed to facilitate the easy and efficient use of BIM standards, requirements, processes, and regulations in accordance with ISO 19650, and provides an environment in which all construction stakeholders can collaborate on information and processes without disruption on a single site. Its interface features ISO 19650 templates (OIR, PIR, EIR, AIR, BEP, etc.) based on the UK BIM Framework guidelines and workflows to enable easy and consistent operations. The platform also incorporates the CDE concept to enable the centralized generation, storage, and management of information. It is largely comprised of six modules: Plan, Scope, Contract, Schedule, Track, and Verify. ( 2 ) The US: BEXEL Manager BEXEL Manager is software that supports digital workflows in an open BIM environment according to ISO 19650, and provides a collaborative environment to manage the PIM and AIM information delivery models in a CDE environment. It supports open standard formats such as IFC standards, MVD, BCF, and COBie. Based on an analysis of these two support tools, it was determined that the key factors to consider when introducing them to Korea are whether they support a BIM-based workflow, including BIM contract and requirements management, BIM task performance, BIM data verification, collaboration, information requirements definition, information procurement plan establishment, information management level setting, and open BIM standard formats. The main functions to benchmark are derived in Table 4 based on such analysis results. To create building-level screening indicators, the dataset collected at the building registry level should be matched and integrated (Figure 2, ② Data Preprocessing). However, since publicly collected data is generated for different policy and administrative purposes, there usually is no unique key to link and match the building registry information. Therefore, the location information (latitude and longitude) and address information (street number, dong, ho or suite number) of each data must be processed and linked to match the resolution of the building registry. This task requires string processing technology for non-standardized address and location information, which is quite difficult and requires a substantial budget and time. Approaches to Introduce the ISO 19650-based BIM Information Management Framework to the Republic of Korea The ISO 19650 utilization model is a conceptually defined model that integrates the key components of a digital-based BIM execution workflow and data procurement framework for BIM information management, from a user perspective, to enable unified utilization. The ISO 19650 utilization model was constructed based on the main components of the BIM information management framework derived through the analysis of ISO 19650 and the main functions derived through the analysis of ISO 19650 support tools. The ISO 19650 utilization model consists of six modules, as shown in Figure 4. Module 1 is Standards, which signifies Open BIM standard for exchanging and distributing BIM data and Standards for defining the BIM information management operating system. Module 2 is Requirements, which functions to set information requirements, information management entities and roles, and information procurement plans in project phases such as design and construction and facility operation phases. Module 3 is Workflows, and it is designed to define and manage detailed BIM processes for each project delivery and operational phase. Module 4, Deliverables, defines and manages PIM and AIM data, which are information delivery outputs. Module 5 refers to the CDE environment for collaboration and sharing. Modules 2 and 3 pertain to the process area, while modules 4 and 5 consist of the data area created, shared, and saved according to the process. Modules 2 through 5 need to be operated to achieve a sequential flow. Module 1 is used as a criterion for data creation, and module 6 serves as an interface where the BIM information management entity utilizes modules 1 to 5. The concept of each module can be provided in the form of specifications, such as standards and guidelines, or in the form of platform functions. We propose the following implementation plan and future tasks to apply the ISO 19650 utilization model in practice. First, in order to establish Level 2 of BIM in Korea, it is necessary to customize the major components of ISO 19650 defined in modules 2 through 5 and the open BIM standard defined in module 1 to fit the domestic situation and present it as a national standard. From a regulatory perspective, a strategy is required to gradually expand the mandatory application of ISO 19650 to some public construction companies, and a verification process through pilot projects should be accompanied before making it mandatory. Second, to directly utilize the ISO 19650 utilization model in work, it is necessary to incorporate the workflow of module 3 and develop a BIM project workflow support platform that includes the functions of module 6. For this purpose, it is important to convert document-level specifications into digital specifications and combine clauses and workflow units. In addition, a plan to link ISO 19650's key functions and data with commercial BIM platforms and enterprise ERP systems to operate needs to be prepared to increase the effectiveness of ISO 19650 adoption. Third, with the acceleration of the digital transformation paradigm, proactive future responses are needed, such as revising the BIM roadmap to prepare for the next maturity phase, as well as research on the introduction and stabilization strategy for digital information management maturity Stage 2 and BIM maturity Level 2. Epilogue In the era of digital transformation, the adoption and utilization of ISO 19650 in the global market has become an essential strategy for securing global competitiveness. To proactively respond to these changes domestically, an approach to the adoption of ISO 19650 has been suggested. To implement the core functions that can reflect the main components of ISO 19650 and be applied to practical situations, an ISO 19650 utilization model has been defined, and adoption plans and challenges for implementation in Korea have been proposed. It is anticipated that an adoption plan based on ISO 19650 will be reviewed in devising a national-level BIM information management operation system in the future. Department of Future&Smart Construction Research Date2023-02-27 Hit 113
• Development of AI-based Smart Housing Platform and Intelligent Convergence Housing Service Technology Development of AI-based Smart Housing Platform and Intelligent Convergence Housing Service Technology ▲ Senior Researcher Ahn Ki-uhn, Department of Building Research, KICT Prologue The demand to improve the quality of life and housing welfare of residents is growing, reflecting changes in the sociodemographic structure. Accordingly, a new type of housing infrastructure is also being established in the construction field to incorporate “smart” technologies into the residential space itself thanks to the spread of Fourth Industrial Revolution technologies such as AI, IoT, and Cloud. Existing smart home services are dependent on manufacturers and construction companies, from which all households and complexes are provided with a common platform and services; residents lack the freedom to select services, and there are restrictions on the introduction of new services. To overcome this problem, a smart housing environment is being built to support the independence of residents in selecting and using services through a platform with openness and scalability, where anyone can develop and register various services. The goal of this article is to introduce the concept and development direction of smart housing platforms and services that support the new housing infrastructure. The Concept of Smart Housing Smart housing is housing that provides an optimized spatial environment and services by linking and converging a physical smart house comprised of the space, environment, home appliances, devices, etc. which make up a house and related technologies, such as big data information technology, IoT smart home technology, and intelligent AI technology (Figure 1). These houses are realized as a new housing infrastructure, where the residential space itself acts a means of collecting information and providing services. Smart Housing Platform Existing smart home services require new physical components, such as devices and networks, to be newly built to use the services provided by providers. On the other hand, in smart housing, it is possible to provide and expand services without physical resource constraints by securing data and utilizing platform functions through the existing infrastructure, such as residential spaces, complexes, and smart cities. In this section, the smart housing platform service functions operating in the Cloud environment are explained by dividing them into IaaS (infrastructure as a service), PaaS (platform as a service), and SaaS (Software as a service) (Figure 2). IaaS, a physical resource to implement smart housing, consists of sensors for collecting data, gateways for sending and receiving data between sensors and platforms, and servers for data storage, AI analysis, and service operation management. In particular, various sensors and IoT devices are embedded in the infill, allowing them to sense the physical elements of the living space. Gateways can be equipped with multi-protocol conversion handling capabilities to accommodate the networking diversity of data sources. At this time, a standard protocol defining the data format and communications standard are prepared to support wide-area service provision and data utilization. The main functions of smart housing PaaS include security, integrated management of storage, multiple access/distributed processing, and the use of an AI analysis engine. First, security features authorization that grants user authentication and authority, encrypted communications between the housing environment and platform, and encryption and decryption of blockchain-based stored data. Data is managed according to the standard format classification system based on the smart housing standard protocol and supports the utilization of real-time and stored data. In addition, it has analysis/service spaces and functions to distribute and handle multi-processes, for load management according to multi-user access and service execution. PaaS integrates and manages AI models that can be used for residential services by data type, such as time series, voice, and video, in an AI bank, and provides an AI analysis engine API function that can be used for service model development and calculation. Finally, the smart housing SaaS operates and manages intelligent residential services such as fire, crime prevention, comfort, convenience, and maintenance on the platform, and has functions to provide them to requesters using the service. Moreover, by utilizing the AI analysis engine function of PaaS, it has a scalability of functions which allows external developers to freely discover and develop services, and register them on the platform to distribute and operate services. Smart Housing Service To implement smart housing, we are developing AI-based convergence services in the four areas of safety, comfort, convenience, and maintenance by analyzing the needs of residents (Table 1), and are preparing to operate platform-based services. In addition, based on the function of the smart housing platform, new services are being discovered and expanded in various residential spaces and fields (Figure 3). Epilogue The Korea Institute of Civil Engineering and Building Technology (KICT) is conducting research on "AI-based smart housing platform and service technology development" to provide an environment that enables the dissemination, development, and operation of creative and innovative services for high-quality housing environments. Through this research, it is anticipated that the foundation for future-oriented responsive housing welfare will be strengthened, and related industries such as housing services and smart devices will be revitalized by establishing a platform ecosystem in the area of smart housing. Department of Building Research Date2022-12-27 Hit 183
• Trends and Directions of Digital Transformation in the Construction Sector Trends and Directions of Digital Transformation in the Construction Sector ▲ Senior Researcher Kim Jong-hyeob, Department of Construction Policy Research, KICT Prologue With the advent of the Internet and the development of communications technology, the emergence and evolution of the digital transformation have been taking place for a long time. Recently, the Fourth Industrial Revolution and the development of digital technologies (virtual and augmented reality, artificial intelligence, blockchain, mobile technology, big data, Internet of Things, etc.) have been changing the structure of industry, and they are rapidly changing everything, including business processes and business models of companies. In addition, the current government's pledges to support industries stress digital transformation and deregulation as a whole. In such pledges, the digital transformation of all industries is emphasized, and information technologies such as AI, the metaverse, and blockchain are mentioned as catalysts leading digital transformation. On the other hand, the construction industry is evaluated as an industry with very low productivity compared to other industries due to the labor-intensive production system, the disconnection of information between construction project implementation stages (MGI 2017), etc. Considering this, it is necessary to make this an opportunity for the construction industry to achieve innovation that can have a productivity equal to or higher than that of other fields through the systematic promotion of Digital Transformation (DX) and the utilization of Fourth Industrial Revolution technologies. Definition and Current Status of Digital Transformation The dictionary definition of DX can be said to be digital change or digitalization of information, which means a fundamental change and transformation with a higher intensity than the change that has been pursued previously. DX at a high level includes all the profound changes that take place in society and industry through the use of digital technologies. Specifically, it is defined as "bringing about significant changes to and improving the characteristics of entities through a combination of digital technologies (information, computing, communications, etc.)" (Gregory Vial, 2019). DX at the corporate (or organizational) level is "a management strategy that fundamentally changes the system, such as a company's strategy, organization, process, and business model, on a digital basis," and is mainly defined as the use of digital technologies to improve business performance, such as efficiency and productivity. The definition at the corporate level is the most commonly used DX concept, and DX at the social or macro level can be defined as "the process of globalization of individuals, businesses, societies, and countries resulting from digitalization." In 2020, IDC (International Data Corporation) defined the stages of the introduction and application of corporate digital transformation as Stage 1 (Ad Hoc), Stage 2 (Opportunistic), Stage 3 (Repeatable), Stage 4 (Managed), and Stage 5 (Optimized). It announced that more than 60% of construction companies both domestically and overseas are in the early stages of DX, Stage 1 (Ad Hoc Stage) or Stage 2 (Opportunity Stage) (IDC InfoBrief 2020). As for the definition of DX in the construction sector, 68% of South Korean construction companies prioritize DX and interpret it from the enterprise's point of view, so it can be defined as “implementing the operation and growth of new businesses while driving organizational, operational, and business model innovations by using third platforms or emerging technologies” (IDC Info Brief 2020). Currently, digital activities performed by construction companies can be divided into two categories according to their purpose, which are as follows: ① Activities focusing on internal system integration, which refers to "a series of activities to improve work efficiency" (e.g. Big Data-based BIM, DfMA, Robotics, etc.). ②"Fundamental change in the form of construction work" through the integration of the outside of the company, that is, the eco-system (finance, manufacturing and transportation, etc.). However, this is similar to the existing digitalization activities, and the reality is that the definition of DX in the construction industry is still ambiguous. ©Built Robotics, Branch Technology, Q-Bot Ltd., XYZ corp. Examples of DX Application in the Construction Industry Recently, many ConTech companies using BIM, IoT, AR/VR, cloud blockchain, autonomous driving, platform, module, modular, artificial intelligence, cloud, etc. are emerging in the global construction market, and each company is striving to improve their efficiency in construction from various perspectives, including improvement in productivity and added value, risk reduction, and eco-friendly effects. In addition, global ConTech companies that have applied DX to the construction industry are emerging in various countries, including the United Kingdom, France, and Germany, with the United States in the lead. In South Korea, the roadmaps for smart construction technology and construction business production structure innovation were announced to invigorate the application of DX in the government-led construction industry. In addition, the application of DX in the South Korean construction industry is being stimulated through the smart construction technology development project, which has been promoted by the Korea Agency for Infrastructure Technology Advancement (KAIA) since 2020. In addition, South Korean ConTech companies have introduced related technologies applying BIM, Digital Twin, Internet of Things, Modular, etc. at the 2022 Smart Construction EXPO. ©Basis Soft Inc., Hyundai E&C, Angelswing, POSCO A&C Advantages and Expected Effects of Introducing DX into the Construction Industry The introduction of DX into the construction industry can greatly contribute not only to productivity improvements, but also to the acceleration of the conversion to high-value-added businesses, risk reduction, and eco-friendliness in line with ESG trends. With the introduction of digital technology, it is expected that construction productivity will be increased by 25%, added value will grow by 1.42 p, industrial accidents and risks will be reduced, and eco-friendly responses will be possible (waste will be cut down by 3-60% and carbon emissions decreased by 50%) (Samjong KPMG Economic Research Institute, 2021). According to McKinsey Global Institute, DX will enable productivity gains of 14-15% and cost savings of 4-6%. The institute estimated that an increase of KRW 1.6 trillion in added value will be possible if the construction productivity growth (annual average of 1% over the past 20 years) reaches the level of global economic productivity growth (annual average of 2.8% over the past 20 years). However, for DX to be successfully promoted and accomplished in the construction field, it is necessary to clearly define the problems based on the lessons learned from the successes and failures of other industries rather than simply adding digital technology to the construction industry, to make innovative improvements through the application of digital technology, and to reach the level that can change the business competition system. Department of Construction Policy Research Date2022-12-27 Hit 166
• Trends in Fire Safety Technology Using Fourth Industrial Revolution Technologies Trends in Fire Safety Technology Using Fourth Industrial Revolution Technologies ▲ Senior Researcher Ryu Eun-mi, Department of Fire Safety Research, KICT Prologue Fire safety technology has seen less in the way of advancements than other technologies because of the widespread lack of sensitivity to safety in our society, a low investment in technology development by small manufacturers, and difficulties in developing overseas markets due to differing fire safety standards in each country. Therefore, the convergence of the Fourth Industrial Revolution technology and fire safety technology not only facilitates the maintenance and management of firefighting equipment but can also effectively reduce the damage to life and properties caused by fire by extinguishing a fire more quickly. In addition, it will help to accurately grasp the situation at the site and promptly mobilize resources to the fire scene, thereby increasing the efficiency of firefighting activities and securing the safety of firefighters. Smart fire safety technology can expand the scale of the firefighting market by becoming the basis for advancing into overseas markets. In this article, I would like to briefly introduce the existing fire safety system and the current status of firefighting equipment technology using Fourth Industrial Revolution technology. Existing Fire Safety Systems Existing fire safety systems notify the people inside the building, the administrators, and the fire departments of the occurrence of a fire through an automated fire detection system. Following this, the administrators guide people inside the building to safely evacuate, and the firefighters extinguish the fire. Components of an automatic fire detection system include a receiver, a transmitter, a detector, and an alarm. Receivers are classified into P-type, R-type, and M-type according to the detector and size. The P-type receiver is the most basic type of receivers and is applied to many buildings. Since it uses a common signal method by individual signal lines as a boundary area for signal transmission, the exact location of the fire cannot be accurately identified. On the other hand, the R-type receiver uses a multi-type communication line method and is mainly applied to large-scale complexes or high-rise buildings. Existing fire safety systems have different degrees of fire detection, confirmation, and response depending on which detectors, repeaters, receivers, and transmitters are installed. Recently, when an R-type receiver and an analog detector are used, the location of a fire can be identified in some cases. However, since it is impossible to check information on the growth and spread of a fire after it has occurred, the reality is that there is a lack of fire information that would support the efficient evacuation of people inside. Trends in Patents for Firefighting System Technologies Using IoT and ICT Technologies Looking at the trend of patents for firefighting systems using Fourth Industrial Revolution technology, as shown in Figure 2, from 1999 to 2014, the early period of analysis, a slow increase was observed, but from 2015 to the present, it increased rapidly. South Korea holds an approximately 57% share of the related patents, giving it the largest number of patented technologies. Since Korea is leading the overall trend, the overall trend is also showing a rapid increase according to the fast growth in Korean applications filed for patents. However, since the number of patent applications filed by most applicants of Korean nationality is a mere 1 or 2 cases, it is hard to describe this as a situation in which continuous R&D is being conducted in South Korea compared to other countries for firefighting system technology using Fourth Industrial Revolution technology. Fire Safety System Using Fourth Industrial Revolution Technologies Conventional receivers make it possible to determine the time and location of a fire, but not to identify the number of people in a building and their locations as well as judge their evacuation routes. Recently, however, IoT-based firefighting system technologies that can collect data in real-time with sensors attached and fire safety response technologies to improve safety and reliability by predicting fires using artificial intelligence (AI)-based technologies have been actively researched. In addition, as shown in Figure 3, studies have recently been conducted that seek to predict the growth and spread of fire by installing a gateway in existing fire safety systems to collect fire data and analyze it. These fire safety technologies can provide optimized evacuation routes for people in the building on fire, enable administrators to monitor a fire in real time, and allow firefighters to effectively suppress fires, minimizing the loss of life and damage to property as a result. Future Direction When a fire occurs, there is an urgent need for a fire safety system that can identify the exact fire situation within the building, evacuate people within the golden hour, and minimize property damage. Given such conditions, it is expected that fire safety systems using Fourth Industrial Revolution technologies will rapidly grow in the future. However, a fire safety system using Fourth Industrial Revolution technology has limitations in that commercialization is difficult because it must be approved through a verification system, and there are various legal and institutional obstacles, such as the Act on the Protection and Use of Location Information and the Personal Information Protection Act. Therefore, it is necessary to grant a regulatory grace period to the relevant industries so that related technologies can be actively researched while minimizing any problems that could follow the introduction of these technologies. Department of Fire Safety Research Date2022-12-27 Hit 131
• Development of Practical Technology for Maintenance-oriented Concrete Overlay With a Life Expectancy of 20 Years Development of Practical Technology for Maintenance-oriented Concrete Overlay With a Life Expectancy of 20 Years ▲ Research Fellow Nam Jeong-hee, Department of Highway & Transportation Research, KICT Prologue According to Yearbook of Road Statistics (2020) published by Korea’s Ministry of Land, Infrastructure and Transport (MOLIT), the length of cement concrete pavement has steadily increased since 2000, accounting for approximately 65.63% (12,956 km) of the total length of highways (primary roads). However, it is worth noting that a significant portion of this pavement, as much as 19.51% (2,528 km), is targeted in mid- to long-term remodeling plans due to aging. The increased aging of cement concrete pavement inevitably leads to an increase in maintenance budget requirements. Considering that the budget for highway maintenance, which was KRW 34.9 billion in 2001, had increased to KRW 154.7 billion by 2020, a staggering 4.43-fold rise, it is clear that there is now an urgent need to establish effective maintenance measures. Over the past four years, we have conducted research on the development of an overlay method for cement concrete paving, which can overcome the limitations of partial cross-sectional repair and ensure longevity and high durability by using materials in the same series as the existing deteriorated cement concrete paving. One of our major achievements in this area is the successful practical application of an overlay method that maximizes durability through reinforcement of continuously reinforced concrete pavements, enabling an expected service life improvement of over 20 years through maintenance. Currently, we are in the process of negotiating a technology transfer. Development of Technology for Practical Application of Continuously Reinforced Concrete Pavement (CRCP) Overlay Maintenance Method Known for its excellent durability and cost-effectiveness, the Bonded Concrete Overlay (BCO) method is a pavement maintenance technique in which concrete is overlaid after cutting the deteriorated existing concrete layer. Compared to asphalt overlay methods, it has a relatively long service life and superior load-bearing capacity for increased traffic volumes and heavy vehicles, resulting in a significant reduction in maintenance frequency and costs. Additionally, it is evaluated as an economical maintenance alternative since it has material properties that are similar to the existing concrete pavement, resulting in less pavement damage after maintenance. The existing concrete overlay method for Jointed Plain Concrete Pavement (JPCP) involves placing concrete on top of the deteriorated JPCP and installing joints in the same position as those of the existing pavement. However, the joint area is the weakest part of the concrete pavement, and from the perspective of repair and reinforcement, installing joints in the same position as those of the existing pavement may ultimately have limitations when it comes to improving usability for public use. Accordingly, we have developed an innovative method for overlaying joint concrete pavements with longer service life compared to conventional methods, called the Ultra-Thin Continuously Reinforced Concrete Pavement maintenance method (hereinafter referred to as “UT-CRCP”), which employs reinforcing materials such as steel bars to restrict joint movement and eliminate them. UT-CRCP involves cutting the deteriorated surface of existing pavement and overlaying it with a thin layer of concrete. This method induces the two pavement layers (overlay and existing pavement layers) to behave as a single unit by completely bonding them together using continuously reinforced steel bars. The key concept of this method is the removal of deteriorated areas and improvement of the surface of the pavement while enhancing its structural capacity with reinforcement materials. An important prerequisite for achieving this is that the existing pavement must maintain sufficient support for loads, and the overlay layer must be completely attached to the existing pavement. Considering that the reality in Korea is that concrete pavement is frequently damaged at joint areas, it is important to disperse stress concentration on existing joint areas through the effective placement of continuous reinforcement bars during overlay, and to enhance long-term durability through limited joint width movement. The core idea of the construction aspect for practical application is the development of the one-lane paving method for reinforcement installation, which enables maintenance using only one lane to minimize one-lane paving closures and the associated traffic congestion that inevitably occurs when maintaining and repairing deteriorated concrete roads used by the public. One of our major research accomplishments in this area is the large-scale test construction carried out over four occasions for the practical application of the UT-CRCP. The 1st and 2nd test constructions were conducted at the SOC Demonstration Research Center of the Korea Institute of Civil Engineering and Building Technology (KICT) in Yeoncheon, Gyeonggi-do, where a 60m-scale UT-CRCP was constructed. Through this test construction, the constructability of the equipment developed for the one-lane paving closure method was evaluated, and the field applicability of normal reinforced concrete using type 1 cement was also verified. In addition, the service life of the UT-CRCP under environmental and axle loads was assessed using buried-type sensors. Analyzing the movement behavior of the existing JPCP and UT-CRCP before and after construction under changing environmental loads, it was found that the crack width behavior of the UT-CRCP was reduced by approximately 88% compared to the existing JPCP joint behavior, which clearly can be attributed to the continuous reinforcement effect. This phenomenon shows the possibility that the joint behavior of the existing JPCP can be transformed into the crack behavior of the CRCP through maintenance. Based on the results of the two previous test constructions, the 3rd test construction made an extension of approximately 102 m at the Ribisagori section of National Route 37 in Paju through cooperation with the Ministry of Land, Infrastructure and Transport (MOLIT) and the Uijeongbu National Highway Management Office, and the 4th test construction was completed in May 2022 on a national highway in Hongcheon. These test constructions have demonstrated excellent performance to date. Provision of High-Quality Road Services Focused on User Needs through Maintenance In this paper, we introduced the characteristics and advantages of a new type of maintenance method that can be applied to aging cement concrete pavement. In other words, this method not only can extend the structural lifespan of deteriorated roads through cement concrete pavement overlay maintenance, but also can provide additional services such as improving driving comfort for users and reducing road noise due to continuous construction. Ultimately, we hope that the outcome of this study will present a new vision for the future of concrete pavement through practical application. Department of Highway & Transportation Research Date2022-12-27 Hit 67
• Development of Environmental Simulator and Advanced Construction Technologies Over TRL6 in Extreme Conditions Development of Environmental Simulator and Advanced Construction Technologies Over TRL6 in Extreme Conditions ▲ Senior Research Fellow Shin Hyu-soung, KICT Department of Future & Smart Construction Research Prologue In May 2021, South Korea became the 10th participating country in the “Artemis Accords” project, an international piloted lunar exploration program led by NASA. As not only the United States but also Europe, China, Japan, and India have announced plans for lunar exploration, it feels as if the dream of space construction which had previously seemed far away has become more concrete. Furthermore, looking at Korea, which has not yet performed a concrete mission, it even makes one feel impatient to think that Korea may be falling behind again. The recent discovery of large amounts of ice in the lunar poles has accelerated the competition for lunar exploration. This is because ice not only can provide fuel for rockets, but also water and oxygen, which are essential for sustaining the life of astronauts. The Moon's gravity is only one-sixth that of the Earth's, which makes it easier to get out of the gravisphere with relatively little fuel. Therefore, the usability of the Moon as a stopover is growing, because space missions can depart from the Earth, recharge their fuel on the Moon, and take off to deep space such as Mars. In addition, since the Moon is close to the Earth, it is a good place to prepare various technologies to be used in outer space and on other planets and to conduct various scientific studies, which further increases the value of the Moon. All of these are reasons why many countries around the world intend to build bases on the Moon and use them for the long-term residence of astronauts. The Korea Institute of Civil Engineering and Building Technology (KICT) has been leading space construction research through the BIG Project since 2016. To strategically respond to the shifts in the space development paradigm caused by the efforts of nations around the globe, such as space base construction and resource development, this study aims to secure core construction technologies applicable in outer space, an ultra-extreme environment. Centering on the achievements of the 6th year (2021) of the study, this article aims to introduce the development status of the four core technologies in detail: Development of a full-scale chamber for realizing extraterrestrial planetary ground environment and verification technology; infrastructure construction technology using extraterrestrial planetary local materials; technology for the informatization of space for construction on the ground of planets; as well as the development of planetary ground investigation equipment and the planetary underground informatization technology. Development of a Full-scale Chamber for Realizing Extraterrestrial Planetary Ground Environment and Verification Technology The Full-Scale Dusty Thermal Vacuum Chamber (DTVC), which simulates the extreme lunar surface environment, is used to minimize the risk of failure in the real extraterrestrial space environment by verifying various technologies and equipment developed for lunar exploration. This DTVC was made in 2017 and installed in the Future Convergence Building, and was completed in 2019 after undergoing a stabilization test. The internal scale of DTVC is 50 m3, and it can simulate the temperature (from -190 ℃ to +150 ℃) and vacuum conditions (exclusive of ground: 10-6 mbar, Inclusive of ground: 10-4 mbar) of the lunar surface, and a large amount of lunar simulant is put inside the chamber to evaluate the impact of cosmic dust, etc. (Figure 1). The Dirty Thermal Vacuum Chamber (DTVC)'s performance in creating vacuum and temperature environments has been secured through studies in Years 1 through 5. In 2021, studies were carried out for the simulation of ground temperature conditions according to the lunar night and day conditions; the measurement of the thermal conductivity of the ground according to the vacuum pressure for creating the ice ground; as well as the system for simulating electrostatic charging environments on the lunar surface and its measurement study. As the lunar surface has no atmosphere, the temperature near the equator can rise to 120 °C during the day, and can drop to as low as -170 °C at night. However, since the thermal conductivity of lunar simulant is low in a vacuum environment, the temperature change of the soils below 10 cm depth is not large, and the low-temperature state is maintained. The soil temperature according to the depth in the low/high-temperature environment of the full-scale chamber constructed based on these data was measured (Figure 2), and further study will continue to improve the performance of simulating the temperature of the ground. In addition to temperature and vacuum, the characteristic lunar surface environmental condition is electrical, which shows a positive potential of less than +20 V under the influence of sunlight during the day and a negative potential of hundreds to thousands of V at night under the influence of the Earth's plasma (Figure 3). This characteristic is considered a threat to the long-term residence of astronauts and equipment on the lunar surface, and it is necessary to understand and develop technologies to address it. To simulate this electrical environment in the DTVC, an electrification environment simulation system using ultraviolet lamps and electron beams was built in a small vacuum chamber (Figure 4). Based on the electrical data on the lunar surface, a similar environmental simulation and a measurement method were devised. In this year, the 7th year of the DTVC, a study on ground cooling in the chamber and measuring the potential of the ground charged with static electricity in an electrical electrification environment will be conducted. Through such research, it is planned to advance the environmental simulation performance of the DTVC and develop it into a more reliable construction technology verification facility in the lunar environment. Infrastructure Construction Technology Using Local Materials of Extraterrestrial Planets To build a lunar base, construction materials are needed. As the cost of transporting such materials from the Earth to the Moon would be astronomical, it is essential to develop a technology that makes it possible to produce construction materials using resources available on the Moon. To this end, a study is being conducted to solidify the “Lunar Simulant,” local resources available on the Moon, through a microwave-sintering technology in order to use it as a construction material. Sintered pellets of lunar simulants are created when lunar simulants (KLS-1) are densified at a temperature of 1,080°C or higher through the microwave-sintering method, and the density and compressive strength of the sintered pellets are increased as the sintering temperature rises. The thermal expansion characteristics of all materials used in the construction of the lunar base are very important, as repeated contraction and expansion of construction materials with the extreme temperature change of the Moon can cause cracks in the structure. The thermal expansion coefficient of the sintered pellets of lunar simulants produced by the microwave sintering method is about 5 × 10-6 °C-1 within a range similar to the lunar surface temperature (from -100 to 200 ℃), which was confirmed as similar to the thermal expansion coefficient of actual lunar rock. In addition, the thermal expansion coefficient of the sintered pellets of the lunar simulants did not change significantly even after processes of heating-cooling-reheating, so it was confirmed that the microwave sintered lunar simulant had high thermal resistance even under the Moon’s extreme temperature changes. To use the sintered pellets of the lunar simulant as a lunar base construction material, it is first necessary to review their homogeneity. In this study, the porosity was estimated through the Statistical Phase Fraction (SPF) method using X-ray CT images of the sintered pellets of lunar simulant to evaluate the homogeneity based on the porosity distribution of the material. It was confirmed that the total porosity of the sintered pellet of lunar simulants, estimated by the SPF method, was almost identical to the porosity calculated through the density analysis. Through estimating the local porosity of the local sintered pellets by dividing the CT image of the sintered pellet of lunar simulants into unit cells with a constant volume, it was confirmed that the mean porosity of 1,080 ℃ and 1,100 ℃ sintered pellets of lunar simulants were 30.4±2.1% and 27.1±2.9%, respectively, and distributed in the ranges of 26-40% and 20-36%. At the same height, the porosity decreases from the outside to the inside of the sintered pellet. This is due to the characteristics of microwave heating, which has a higher internal than external temperature, and it can be seen that a denser structure is formed in the center of the sample. Currently, sintered block of lunar simulant is being manufactured to increase its utility as a construction material, and to apply microwave sintering technology to a real lunar high vacuum environment, microwave vacuum sintering equipment must be built and sintering experiments conducted. Technology for Informatization of Space for Construction on Extraterrestrial Planetary Ground To select the optimal site for the construction of a lunar base, a lunar topography survey is essential. However, Global Positioning System (GPS) is not available on the Moon, and the Moon's Permanently Shadowed Regions are low illuminance areas without sunlight. Therefore, this study aimed to develop a real-time 3D topographical information technology based on an unpiloted vehicle that can be used to construct the high-precision 3D topographic map required for design and construction on the lunar surface. In this study, research was conducted to acquire real-time three-dimensional topographic information in low illuminance and GPU-shadowed environments by using a sensor combination of a stereo camera mounted on an unpiloted vehicle and an Inertial Measurement Unit (IMU). In particular, a self-supervised CNN-based image enhancement module was developed to maximize mapping performance in a low illuminance environment, and mapping performance with a mean error of less than 7 cm in a low illuminance environment was secured. In addition, simulated planetary topography consisting of craters, rocks, hills, soil, and gravel areas was built in the KICT's indoor simulated terrain laboratory and SOC Demonstration Research Center (Yeoncheon), and verification experiments for unpiloted topography informatization technology were conducted (Figure 7). The research was conducted on object recognition in images of constructed simulated extraterrestrial planetary topography, region classification, and evaluation of the similarity of the same object in other images. To automatically classify objects and regions of interest in the targeted areas, a topography and terrain feature recognition and region classification technique using Mask R-CNN, an open source program for deep learning region recognition, was developed. We also developed a matching method for identical object and terrain features in multiple images using the Triplet network, and completed a major object matching system between aerial photos and unpiloted-vehicle topographic images (Figure 8). In the future, we plan to develop a GIS-based unpiloted topography informatization technology system by improving the accuracy of unpiloted topography informatization technology and artificial intelligence object matching technique and combining them. Development of Extraterrestrial Planetary Ground Investigation Equipment and Extraterrestrial Planetary Underground Informatization Technology Moon explorations, which had stalled for a while after humans first successfully landed on the Moon, began to become active again when the existence of ice at the lunar poles was confirmed. To analyze the ice and underground resources that exist at the poles of the Moon, drilling equipment must be mounted on the exploratory Lander or Rover. In order to transport and operate such equipment on the Moon, an extreme environment, requirements in terms of small size, light weight, low power, high efficiency, and high performance have to be met. In this study, a prototype of drilling equipment that can be operated in atmospheric pressure and low temperature environments was first developed. In addition, in consideration of transportation needs, miniaturization of 0.27 m3 grade, weight reduction of 18.5 kg grade, and low power consumption of 44.4 W grade were secured. Prototype drilling equipment was pre-verified using artificial ice in the freezing chamber, and a field study was conducted under low power, low reaction, and waterless conditions for sea ice and frozen soils around the Jang Bogo Research Station to evaluate the drilling performance and identify problems in drilling the sea ice frost heaving (Figure 9). By performing the drilling performance and reliability evaluation under various local conditions, it was confirmed that drilling failure due to slip of the bit-cutting area occurred when the vertical reaction was 25 N or less, and drilling failure due to jamming occurred when it was 125 N or more. In the range of vertical reaction of 50 to 100 N and rotation speed of 25 to 125 rpm, drilling reliability of at least 60% was secured. Epilogue The construction of a space base, a dream of humankind for decades, is gradually becoming a reality. Space powers are competing with each other in terms of piloted lunar exploration and base construction plans to be the first to occupy the Moon. Relatively speaking, Korea's space development research lags far behind. However, the space construction field, which has just taken its first steps, has relatively low entry barriers compared to other space fields. As such, simply by securing the core technologies Korea can enter the ranks of advanced countries at the forefront of space exploration. It is hoped that the space construction technology developed by the KICT will be the first core technology to open the gates, and that it will leap forward as an institution leading the global space construction field in the future. Department of Future&Smart Construction Research Date2022-09-27 Hit 285
• Special Bridge Safety Inspection Technology Utilizing Robots Special Bridge Safety Inspection Technology Utilizing Robots ▲ Senior Researcher Seo Dong-woo, KICT Department of Structural Engineering Research Prologue Most of the structures currently constructed as special bridges in Korea (collectively referring to cable-stayed bridges on which the measurement system is built) are constructed in the form of cable-stayed bridges or suspension bridges. Since the service life required for special bridges is more than 100 years, the stability, durability, and usability of the structure must be secured (KSCE, 2006). Damage to cables, which is one of the key deficiencies in special bridges, is a major factor reducing bridge safety and shortening service life. Cable damage is caused not only by environmental factors (climate, load, earthquake, etc.) but also by unpredictable accidents such as fire or collision. If a bridge in public use must suspend its operation due to cable damage, the economic and social losses are enormous (Na et al., 2014). In Korea, there was an accident in which one out of a total of 144 construction materials was completely broken and two were partially damaged by a cable fire at Seohae Bridge (cable-stayed bridge) (Gil et al., 2016). Although studies aiming to develop various inspection technologies for the safety and maintenance of cables are being conducted, there is a limit to the applicability of these technologies to special bridges, especially to cables, which are large facilities, due to limitations in the mobility and accessibility of equipment. To address this, efforts to develop a cable inspection robot capable of non-destructive testing are ongoing (Kim et al., 2014). To apply the inspection robot to cables, it is necessary to secure its field usability by using a wireless system and minimizing dead-weight. In this article, I would like to introduce a cable inspection robot equipped with an electromagnetic sensor to improve the driving stability, which was pointed out as a disadvantage of existing inspection robots, and to detect whether the inside of the cable is damaged. Design and Specifications of Cable Inspection Robot In making the cable inspection robot, we focused on the applicability of large diameter cables over 200 mm and securing the robot's driving stability. Figure 1 shows the 3D image of the cable inspection robot and its main devices. The dimensions of the robot are 510 mm × 610 mm × 710 mm, and the weight is reduced to 12.8 kg. In addition, to improve durability, the frame of the robot was made of aluminum. A high-resolution IP camera (1920 × 1080 pixels) was installed to take pictures of the exterior of the cable, enabling real-time cable shot images to be transmitted with a wireless Wi-Fi router. Furthermore, the movement distance of the robot could be calculated using an acceleration sensor and a rotary encoder. Three driving motors (IG-32GM, DC12) and urethane wheels were installed so that the robot can move on the cable while minimizing its shaking during climbing. In addition, a variable diameter adjustment part (140-300 mm) was made to improve the adhesion between wheel and cable. The wireless remote control of the robot uses IEEE 802.11 an/ac 5 GHz 2×2 MIMO to achieve a communication distance of 10 km and a data transmission rate of up to 867 Mbps. Damage to the steel wire of cables is detected with an electromagnetic sensor. As shown in Figure 2, the principle applied is that the polarity is divided again at the damaged area when the cable breaks or gets damaged. As shown in Figure 3, the sensing device mounted on the inspection robot for cable damage detection consists of pipe diameter adjusting units that can be adjusted according to the cable diameter and a roller for moving on the cable surface. Also, the electromagnetic sensor for detecting cable damage is inserted in the middle of the roller part. Performance Evaluation of Cable Inspection Robot Indoor and outdoor tests to evaluate the driving performance of the cable inspection robot were conducted as shown in Figure 4. One cable-stayed bridge with a history of cable accidents was selected as a test bed bridge for field tests of bridges currently in public use. The bridge is a short-span earth-anchored steel composite cable-stayed bridge with a span length of 400 m and a width of 23.9 m, on a four-lane road (two ways). The field cable (200 mm) had an inclination angle of 27.3 degrees, and the indoor test was conducted at 45 degrees. With the verification test, the climbing speed (19 cm/s) and the descent speed (20 cm/s) were evaluated, and it was confirmed that the robot is effectively controlling its speed when the speed increases due to slipping that may occur during the descent. It was also confirmed that the driving speed was constant regardless of the inclination angle. In addition, real-time images of the cable surface were taken with three cameras in the field test, and as shown in Figure 5, it was confirmed that visual inspection of the cable was possible. No communication-related problems occurred during the performance verification test. The cable damage detection test was conducted indoors. The cable specimen used in the indoor test is a type of cable currently used in bridges, and the inner cable consists of 20 pieces of one bundle composed of seven 1.57 mm strands. For the cable sheathing, the same High-Density Polyethylene (HDPE) tube used in the driving capability test was used. To detect cable damage, damage types were artificially simulated as shown in Figure 6. Cut damage was subdivided according to the degree of cross-sectional cut into 30%, 50%, and 100% cut (break). For disengagement damage, the case where the cable protruded to the outside in a tidy state was reproduced. For disconnection, one cable was made short. Figure 7 shows the results of the test conducted indoors. In the graph, the X-axis is time and the Y-axis is the electromagnetic sensor measurement. It can be seen that the phase of the electromagnetic sensor measurement changed by 180 degrees at the point where damage (cut) took place. On the other hand, it was confirmed that the phase of the electromagnetic sensor measured value did not change during disconnection, but the magnitude of the magnetic field increased. To secure the reliability of the experimental results, it is considered that additional experiments are needed, with more diverse damage types and repeatability than those conducted in this study. Epilogue This article introduced the development of a cable inspection robot capable of measuring large-diameter cables over 200 mm. The developed cable inspection robot has expanded its field applicability by improving its driving ability, driving stability, and wireless communication performance. The possibility of detecting damage to the inside of the cable using an electromagnetic sensor was verified through an indoor test. However, it is considered necessary to further improve inspection efficiency by developing an analysis algorithm that in addition to detecting the presence of cable damage can determine the degree and type of damage through additional tests. If facility maintenance technology using inspection robots is continuously advanced and applied, it is expected that it will greatly contribute to facility safety management. This cable inspection robot was developed with budget support by the Ministry of Land, Infrastructure, and Transport. It has been handed over to the Korea Authority of Land & Infrastructure Safety and is being used for the maintenance of general national highway special bridges. Department of Structural Engineering Research Date2022-09-27 Hit 263
• Modular Multifamily Housing in Korea and its Future Role Modular Multifamily Housing in Korea and its Future Role ▲ Research Specialist Boo Yoon-sub, KICT Department of Building Research Prologue One of the eco-friendly construction methods, in modular construction, modules produced at a factory are used to complete a construction project on site. At the same time as on-site construction such as bed excavation and foundation construction are carried out, the module is made at an off-site factory dedicated to modular fabrication and brought to the site for assembly. Accordingly, the modular construction method has the substantial advantage of being able to reduce the construction period by almost half because external factors that can delay the construction schedule on-site, such as particulate matter and civil complaints, are minimized. Modular construction can be divided into two types: the floor-by-floor method, in which modules are stacked on site, and the infill method, which involves installation as if inserting into a structure equipped with column-beam-slab (Figure 1). Based on the materials constituting the modules, the modules can be classified into steel-framed modules and concrete-based modules. Steel-framed modules have advantages such as high strength, high durability, and excellent machinability, because modular beams, columns, etc. are fabricated using high-quality steel. However, unlike concrete modules, the steel-framed module requires separate details to secure fire resistance. In addition, compared to concrete modules, the production cost is relatively high, and it is necessary to solve the problem of being somewhat vulnerable to vibration. Concrete modules have the advantages of high strength, fire resistance, excellent anti-vibration, and economic feasibility, as floors, wall units, etc. are fabricated using precast concrete (PC). However, since they are heavier than steel-framed modules, there is a difficulty in lifting for high-rises, which must be overcome for high-rise modular construction with more than 20 stories (Table 1). Trends in Modular Multifamily Housing in Korea Modular multifamily housing in Korea mainly uses steel-framed modules. As a national R&D demonstration project, the Korea Institute of Civil Engineering and Building Technology (KICT) promoted the public housing project of a Modular Demonstration Complex in Gayang-dong in Seoul (2017) together with the Seoul Housingㅍ& Communities Corporation (SH). It also constructed the Modular Demonstration Complex in Dujeong-dong in Cheonan (2019) jointly with the Korea Land and Housing Corporation (LH). Both were supplied as the first multifamily public housing to comply with housing performance standards. After that, public sector bodies such as local governments provided modular housing with six stories or less above the ground as rental housing. The KICT is conducting a mid to high-rise modular public housing demonstration project (hereinafter referred to as “Gyeonggi Happy Housing”) in Yeongdeok-dong, Yongin, Gyeonggi-do in collaboration with the Gyeonggi Housing & Urban Development Corporation (GH). Gyeonggi Happy Housing, which at 13 stories (106 households) is the highest-rising public housing project in Korea, plans to apply the achievements developed by the mid to high-rise modular research group, such as design engineering, off-site construction method, and on-site management. The three-hour fire resistance pointed out as a disadvantage of the steel-framed modular housing above was secured for the first time in Korea through an accreditation test by an accredited institution, and on-site construction is underway with the goal of completion at the end of 2022. The SH is carrying forward a 12-story modular public housing project in Garibong-dong, Seoul (246 households), and a 10-story modular public housing project (512 households) in downtown Seoul. The LH provided public silver housing (152 households) in Ongjin-gun, Incheon by applying the modular construction method, and pushing ahead with the modular public housing project in Sejong City, etc. The government is considering early move-in by converting part of the public housing in the third new city to a modular construction method. For concrete modules, KC Industry, a private company, jointly developed a PC box-type module with the KICT and built a modular building for promotion purposes at its headquarters in Yeoju and its branch in Jeju. It entered the housing market focusing on private housing with one to two stories. In addition, it is expected that the PC box-type modular housing will be able to be supplied as low-rise multifamily public housing of five stories or less, as it has secured structural safety and residential performance. Role of Modular Multifamily Housing For modular public housing, it is most important to resolve the problem of lack of public understanding in relation to off-site construction, and dispel misconceptions about poor residential performance compared to reinforced concrete (RC) construction. After the completion of the Gyeonggi Happy Housing promoted by the KICT as well as the modular multifamily public housing promoted by the public sector, through a thorough review of housing performance, it is necessary to inform the public that modular housing can also secure residential performance equivalent to that of RC multifamily public housing. In addition, it is necessary to pioneer a housing market that applies a modular construction method. Since 2015, the housing crisis has been exacerbated due to a decrease in the number of authorizations and permissions for housing construction, a surge in the number of households caused by the concentration of population in metropolitan areas and division of households, and a shortage of high-quality housing stock. The current housing policy focuses on large-scale housing supply that can be expected after the passage of at least five years, such as large-scale housing site development, reconstruction, and redevelopment. As such, it is difficult to satisfy the current demand for housing, such as for single or two-person households in downtown areas. If local governments and local housing corporations provide a fast and timely supply of modular public housing to small publicly owned sites, it will be possible to flexibly respond to the issue by utilizing the modular construction method to fill the gaps that are not affected by the housing policy. Department of Building Research Date2022-09-27 Hit 298
• Development of Nondestructive Evaluation Technology for PSC Structures (PSC Stethoscope) Development of Nondestructive Evaluation Technology for PSC Structures (PSC Stethoscope) ▲ Senior Researcher Park Kwang-yeun, KICT Department of Structural Engineering Research The Aging of PSC Structures and Need for External PS Tendon Nondestructive Testing Whether at home or abroad, in countries where civilization has progressed rapidly, a number of bridges containing the essence of civil engineering technology have been built, allowing logistics and passengers to quickly cross rivers and valleys. In South Korea as well, befitting a civilized country, many bridges have been built and are playing numerous roles. These bridges enable convenient crossing of the Han River to bind the Gangbuk and Gangnam areas into a single city, overcome mountain valleys to greatly increase accessibility to mountainous regions, and connect islands to the mainland. It is found that 38% of these bridges were built using pre-stressed concrete (PSC) structures. Given the fact that a large number of bridges have been built since the 1980s and 1990s when Korea's economy grew rapidly, it can be assumed that the development of safety diagnosis technology for PSC structures older than 30 years is urgent. As the name suggests, the pre-stressed tendon (PS tendon) plays the most critical role in the PSC structure. PS tendons can be broadly classified into external PS tendons and internal PS tendons. For example, regarding external PS tendons, there was a case of enormous economic and social loss in 2016 due to corrosion of external PS tendons on Jeongneungcheon Viaduct, the inner ring road in Seoul, raising public awareness of the need for safety diagnosis (Figure 1). State of External PS Tendon Nondestructive Testing Technology Taking the Jeongneungcheon Viaduct case as an opportunity, the Korea Institute of Civil Engineering and Building Technology (KICT) conducted the KICT Blind Test (2016), targeting domestic and foreign nondestructive testing technologies to investigate the technology that can assess the integrity of external PS tendons. The integrity of the external PS tendon can be checked using three indicators: sectional damage, stress, and voids. However, for stress, no organization possessed the related technology, regardless of location at home or abroad, and for voids, only one French company (Advitam) applied for and demonstrated a detection rate of about 73%. Among the three indicators, cross-sectional damage is the most important and direct indicator. Of the ten local and foreign companies that applied for related nondestructive technology, only two companies, Tokyo-Rope of Japan and Instron of Russia, showed valid results, and none of the Korean companies demonstrated valid results. As for the technology of the two companies, which showed valid results, we came to the conclusion that it would be difficult to apply it in the field unless the cost, usability, size, and weight of equipment were improved. Development of Nondestructive Evaluation Technology for PSC Structures (PSC Stethoscope) For this reason, the KICT initiated a study to develop a proprietary technology that can inspect cross-section damage, stress state, and voids by conducting nondestructive testing of external PS tendons. The cross-sectional damage and stress use the magnetic properties of the external PS tendon made of metal, and the presence or absence of voids is inspected by applying radar technology. In this article, I would like to briefly introduce a technology for nondestructive testing of sectional damage, which is the most important indicator to assess the integrity of PS tendons. Underlying Concept of Nondestructive Testing Sensor Figure 2 shows the conceptual diagram of the developed electromagnetic sensor installed on the external PS tendon. Although the external PS tendon (the red-brown part in Figure 2) is actually paved with ducts and grouts, the magnetic properties of the duct and grout are almost the same as that of air (or vacuum). Therefore, it can be assumed that there is no magnetic property. The electromagnetic sensor is largely made up of three parts: the primary coil (yellow part in Figure 2), the secondary coil (orange part in Figure 2), and the fixing frame (purple part in Figure 2). The fixing frame is made of plastic that does not respond to magnetic fields. The primary coil is a kind of electromagnet that generates a magnetic field inside the sensor by flowing electricity, and the magnitude of the generated magnetic field is a function of the cross-sectional area of the external PS tendon, a metal component that penetrates the inside of the sensor. The secondary coil is wound to wrap the external PS tendon several times, and if the magnetic field inside the sensor is changed by varying the current applied to the primary coil, an induced current proportional to the magnetic field change is generated in the secondary coil. Using this principle, when AC electricity having a sine wave shape of constant amplitude is passed through the primary coil, AC electricity having an amplitude positively correlated with the cross-sectional area of the external PS tendon is induced in the secondary coil. Therefore, the cross-sectional area of the external PS tendon can be estimated by analyzing the amplitude of the induced AC electricity. The cross-sectional area of the metal component decreases when the external PS tendon is broken or rusted (iron oxide does not respond to a magnetic field). So, it is possible to estimate corrosion and break from the reduction in the cross-section. Development of Sensors Optimized for Field Work As can be seen from Figure 2, the sensor using this principle should have a closed circuit that wraps the external PS tendon. Tokyo-Rope of Japan and Instron of Russia, who were introduced earlier, also share the concepts and basic ideas mentioned above (of course, if you look at the details, they are quite different). However, Japanese and Russian technologies require winding work or equivalent work at the site, as shown in Figure 3, to make a closed circuit wrapping the external PS tendon, which takes a considerable amount of time. Consequently, workability is poor. In addition, since the sensor condition changes every time it is installed, the reliability of the sensor is lowered, and it is disadvantageous to work in the narrow passageway inside the bridge because all the sensor parts must be carried separately to be moved. On the other hand, the electromagnetic sensor developed by the KICT is divided into two, as shown in Figure 4, so with a little mastery, it can be installed within one to two minutes. Furthermore, it was ensured that the reliability of the sensor does not decrease, no matter how many times it is repeatedly installed, by composing the main junction with a highly reliable ready-made connector. The total weight is 5 kg and each side weighs about 2.5 kg, so it is not too heavy for a person to carry. If this sensor is installed as shown in Figure 5 and scanned at an appropriate speed along the external PS tendon, the change in the cross-sectional area can be inspected by performing a nondestructive test for the concerned section. Decision-making Technology Using Signal Processing and Artificial Intelligence Figure 6 shows the results applied to the specimens made to test the developed non-destructive equipment. The cross-sectional area simulating the damage as well as the damaged section are schematized at the top of the Figure. The result, measured by the same process as in Figure 5, is shown as the green line in Figure 6, but it is difficult to distinguish with the naked eyes because the amplitude change is insignificant. When the measured signal goes through several stages of signal processing, such as amplitude demodulation, to help assess the integrity of the external PS tendon using the measurements from the magnetic sensor, the result shown in the red line in Figure 6 can be obtained. In the red line, it can be seen that the change according to the damage to the PS tendon is clearly distinguished. However, a lot of experience is needed to distinguish whether these changes are caused by damage or noise. In addition, it is difficult to obtain information about the extent of the damage. To solve this problem, we developed an algorithm that uses a shallow FRP nerve sensor to specify the location of the damage, as shown in the blue dot in Figure 6, and predicts the ratio of the damage cross-section and even the length of the damage. Moreover, a number of specimens, as shown in Figure 7, were made and used to study artificial intelligence. Epilogue The KICT has developed a technology for nondestructive testing of the external PS tendon, a major element of the PSC structure, to prevent situations such as the Jeongneungcheon Viaduct that occurred in 2016 from being repeated. This technology uses the principle of nondestructive testing of the cross-sectional area made of metal with the application of electromagnetism and enables the repair and reinforcement of the PSC structure by detecting breaks and corrosion of the external PS tendon in advance. We not only developed sensors but also developed technology to help decision-making by improving the usability of sensors and applying signal processing and artificial intelligence to measured signals. The usability of the sensor is continuously improving through close communication with the companies currently in demand. Also, in the case of signal processing and artificial intelligence to help decision making, the algorithm is being enhanced and the accuracy is increased by adding learning data. We are also developing technology for the nondestructive testing of cables in cable bridges using the same principle. If the technology introduced here is completed and enters the bridge maintenance market, it will be possible to prevent huge economic losses through preemptive maintenance of bridges and to help avoid social losses caused by inconvenience to many people. Department of Structural Engineering Research Date2022-06-27 Hit 350

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