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Every year, ceramic tile factories and the iron smelting industry produce huge amounts of waste ceramic tiles and blast furnace slag (BFS), respectively. In the field of construction materials, this waste can be used as a raw material for binders, thus reducing landfill waste and mitigating environmental pollution. The purpose of this study was to mix waste ceramic powder (WCP) into BFS paste and mortar activated by sodium silicate and sodium hydroxide to study its effect on performance. BFS was partially replaced by WCP at the rate of 10–30% by weight. Some experimental studies were conducted on, for example, the fluidity, heat of hydration, compressive strength testing, ultrasonic pulse velocity (UPV), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), electrical resistivity, sulfuric acid attack, and chloride ion diffusion coefficient. Based on the results of these experiments, the conclusions are: (1) increasing the amount of waste ceramic powder in the mixture can improve the fluidity of the alkali-activated paste; (2) adding waste ceramic powder to the alkali-activated mortar can improve the resistance of the mortar to sulfuric acid; (3) adding waste ceramic powder to the alkali-activated mortar can increase the diffusion coefficient of chloride ions; (4) the early strength of alkali-activated mortar is affected by the Ca/Si ratio, while the later strength is affected by the change in the Si/Al ratio.
Gui-Yu Zhang; Yong-Han Ahn; Run-Sheng Lin; Xiao-Yong Wang. Effect of Waste Ceramic Powder on Properties of Alkali-Activated Blast Furnace Slag Paste and Mortar. Polymers 2021, 13, 2817 .
AMA StyleGui-Yu Zhang, Yong-Han Ahn, Run-Sheng Lin, Xiao-Yong Wang. Effect of Waste Ceramic Powder on Properties of Alkali-Activated Blast Furnace Slag Paste and Mortar. Polymers. 2021; 13 (16):2817.
Chicago/Turabian StyleGui-Yu Zhang; Yong-Han Ahn; Run-Sheng Lin; Xiao-Yong Wang. 2021. "Effect of Waste Ceramic Powder on Properties of Alkali-Activated Blast Furnace Slag Paste and Mortar." Polymers 13, no. 16: 2817.
The purpose of this study is to compare the load calculation results by a model using the air changes per hour (ACH) method and a model using an airflow network (AFN) and to ascertain what causes the difference between the two models. In the basic case study, the difference in the heat transfer distribution of the model in the interior space was investigated. The most significant difference between the two models is the heat transfer that results from infiltration. Parameter analysis was performed to investigate the relationship between the difference and the environmental variables. The result shows that the greater the difference is between the air temperature inside the balcony and the outdoor air temperature, and the greater the air flows from the balcony to the residential area, and the greater the heating and cooling load difference occurs. The analysis using the actual weather files of five domestic cities in South Korea rather than a virtual case shows that the differences are not so obvious when the wind blows at a constant speed throughout the year, but are dominant when the wind does not blow during the night and is stronger alongside the occurrence of sunlight during the day.
Yonghan Ahn; Hanbyeol Jang; Junghyon Mun. Comparison of Building Simulation Methods for Modeling Apartment Balconies. Energies 2021, 14, 3955 .
AMA StyleYonghan Ahn, Hanbyeol Jang, Junghyon Mun. Comparison of Building Simulation Methods for Modeling Apartment Balconies. Energies. 2021; 14 (13):3955.
Chicago/Turabian StyleYonghan Ahn; Hanbyeol Jang; Junghyon Mun. 2021. "Comparison of Building Simulation Methods for Modeling Apartment Balconies." Energies 14, no. 13: 3955.
In this study, the total maintenance cost for public houses in South Korea was analyzed, and the effect of each repair process on the total maintenance cost was evaluated with probabilistic and deterministic methods. In the probabilistic method, quality of repair materials and construction skills were considered in the variability of extended service life through repair, while the deterministic method considered it by simple summation of repair step. The repair cost was analyzed considering the coefficient of variation (COV) of extended service life, so the reasonable total maintenance cost was able to be evaluated. Since the results through the probabilistic method provided a continuous cost line, a reasonable repair strategy was carried out by simply changing the intended service life of the structure. The repair cost was additionally analyzed with constant COV (0.15) of each repair process for considering various situations. The analysis results with a COV of 0.15 exhibited a slightly higher maintenance cost than those with current COV. The total maintenance costs can be adjusted if the initial repair timing is extended to the largest possible extent for the highest-repair-cost process since the total repair cost is dominated by the process with the highest repair cost.
Yong-Sik Yoon; Yong-Han Ahn; Xiao-Yong Wang; Seung-Jun Kwon. Total Repair Cost Simulation Considering Multiple Probabilistic Measures and Service Life. Sustainability 2021, 13, 2350 .
AMA StyleYong-Sik Yoon, Yong-Han Ahn, Xiao-Yong Wang, Seung-Jun Kwon. Total Repair Cost Simulation Considering Multiple Probabilistic Measures and Service Life. Sustainability. 2021; 13 (4):2350.
Chicago/Turabian StyleYong-Sik Yoon; Yong-Han Ahn; Xiao-Yong Wang; Seung-Jun Kwon. 2021. "Total Repair Cost Simulation Considering Multiple Probabilistic Measures and Service Life." Sustainability 13, no. 4: 2350.
There has been an increase in the deterioration of buildings and infrastructure in dense urban regions, and several defects in the structures are being exposed. To ensure the effective diagnosis of building conditions, vision-based automatic damage recognition techniques have been developed. However, conventional image processing techniques have some limitations in real-world situations owing to their manual feature extraction approach. To overcome these limitations, a convolutional neural network-based image recognition technique was adopted in this study, and a convolution-based concrete multi-damage recognition neural network (CMDnet) was developed. The image datasets consisted of 1981 types of concrete surface damages, including surface cracks, rebar exposure and delamination, as well as intact. Furthermore, it was experimentally demonstrated that the proposed model could accurately classify the damage types. The results obtained in this study reveal that the proposed model can recognize the different damage types from digital images of the surfaces of concrete structures. The trained CMDnet demonstrated a damage-detection accuracy of 98.9%. Moreover, the proposed model could be applied in automatic damage detection networks to achieve superior performance with regard to concrete surface damage detection and recognition, as well as accelerating efficient damage identification during the diagnosis of deteriorating structures used in civil engineering applications.
Hyun Kyu Shin; Yong Han Ahn; Sang Hyo Lee; Ha Young Kim. Automatic Concrete Damage Recognition Using Multi-Level Attention Convolutional Neural Network. Materials 2020, 13, 5549 .
AMA StyleHyun Kyu Shin, Yong Han Ahn, Sang Hyo Lee, Ha Young Kim. Automatic Concrete Damage Recognition Using Multi-Level Attention Convolutional Neural Network. Materials. 2020; 13 (23):5549.
Chicago/Turabian StyleHyun Kyu Shin; Yong Han Ahn; Sang Hyo Lee; Ha Young Kim. 2020. "Automatic Concrete Damage Recognition Using Multi-Level Attention Convolutional Neural Network." Materials 13, no. 23: 5549.
The sustainability of structures during their construction and service life has become a widespread topic of interest. To ensure the sustainability of bridges, maintenance databases can be analyzed to determine the status changes and required maintenance of existing bridges. The results of this analysis can then be used to predict the environmental impacts and costs incurred during ongoing maintenance of new bridges to prepare accordingly for the future. To prepare for future events, this study utilizes the US National Bridge Inventory to analyze changes in the condition rating of bridge decks and substructures according to their service years, and suggests maintenance scenarios for the service life of bridge deck and substructure concrete by investigating the maintenance activities according to service years. The factors for applying the scenarios in Korea and conceptual equations for life cycle studies which apply the scenarios are discussed for further study in the life cycle assessment field of bridges.
Hyunsik Kim; Sungho Tae; Yonghan Ahn; Jihwan Yang. Scenarios for Life Cycle Studies of Bridge Concrete Structure Maintenance. Sustainability 2020, 12, 9557 .
AMA StyleHyunsik Kim, Sungho Tae, Yonghan Ahn, Jihwan Yang. Scenarios for Life Cycle Studies of Bridge Concrete Structure Maintenance. Sustainability. 2020; 12 (22):9557.
Chicago/Turabian StyleHyunsik Kim; Sungho Tae; Yonghan Ahn; Jihwan Yang. 2020. "Scenarios for Life Cycle Studies of Bridge Concrete Structure Maintenance." Sustainability 12, no. 22: 9557.
The U.S. Green Building Council’s (USGBC) Leadership in Energy and Environmental Design (LEED) certification program supports sustainable construction as part of the effort to address climate change and resource depletion. It is the world’s most popular green building certification system, with more than 146,400 projects. Satisfying the LEED requirements brings many benefits to a project’s design performance and adds community value, but it does incur additional costs and challenges. This study examined the choices made by those working on the 222 LEED New Construction version 4 (LEED-NC-V4) projects that were certified between September 2014 and March 2020 to determine how the LEED project teams selected appropriate LEED goals. The results reveal interesting insights into the way project LEED goals and the credits corresponding to the target certification level were chosen, as well as the links and trade-offs between the various credit options. Based on these findings, useful suggestions are made for ways to help LEED project teams achieve their target certification levels and encourage authorities to continue to improve their local green regulations. The analysis of actual certified projects’ data makes it possible to re-evaluate the effects of newly updated requests in LEED v4 in the light of the stated goals of the USGBC.
Duy Hoang Pham; Byeol Kim; Joosung Lee; Yonghan Ahn. An Investigation of the Selection of LEED Version 4 Credits for Sustainable Building Projects. Applied Sciences 2020, 10, 7081 .
AMA StyleDuy Hoang Pham, Byeol Kim, Joosung Lee, Yonghan Ahn. An Investigation of the Selection of LEED Version 4 Credits for Sustainable Building Projects. Applied Sciences. 2020; 10 (20):7081.
Chicago/Turabian StyleDuy Hoang Pham; Byeol Kim; Joosung Lee; Yonghan Ahn. 2020. "An Investigation of the Selection of LEED Version 4 Credits for Sustainable Building Projects." Applied Sciences 10, no. 20: 7081.
The control strategy of heating, ventilating, and air-conditioning (HVAC) systems is cost-effective to achieve energy saving in buildings. It is believed that identifying representative behavioral patterns of end-users in multi-zone buildings helps personalize the control parameters of HVAC systems. Thus, this will result in energy saving while minimizing thermal discomfort of end-users. With advanced metering technologies, it is possible to capture how end-users consume energy in their rooms and then categorize the rooms into several meaningful groups based on similar energy use patterns. Unfortunately, it is still unknown how changes in numerical values and dimension of energy use data affect the performance of end-user group categorization. Therefore, this research examines the performance of end-user group categorization across different types of numerical values and dimensions of energy use data. A clustering analysis is conducted using energy use data from 959 rooms of seven dormitory buildings in Seoul, South Korea. The clustering results show that reducing the dimension of energy use data (i.e., data reduction) improves the similarity of end-users within a group. Also, transforming the numerical values of energy use data (i.e., data transformation) makes the group similarity higher. Lastly, when combining both data reduction and transformation during the categorization process, the best clustering method is dependent on the distribution of energy use data. These results indicate that facility managers can provide end-users with thermally comfortable conditions and achieve energy saving across all zones.
Kwonsik Song; Joseph Ahn; Yonghan Ahn; Moonsun Park; Nahyun Kwon. Reduction and transformation of energy use data for end-user group categorization in dormitory buildings. Journal of Building Engineering 2020, 32, 101524 .
AMA StyleKwonsik Song, Joseph Ahn, Yonghan Ahn, Moonsun Park, Nahyun Kwon. Reduction and transformation of energy use data for end-user group categorization in dormitory buildings. Journal of Building Engineering. 2020; 32 ():101524.
Chicago/Turabian StyleKwonsik Song; Joseph Ahn; Yonghan Ahn; Moonsun Park; Nahyun Kwon. 2020. "Reduction and transformation of energy use data for end-user group categorization in dormitory buildings." Journal of Building Engineering 32, no. : 101524.
Few studies have assessed the safety issues involved in decommissioning nuclear facilities, especially from a structural and job perspective; in most developed countries, the focus is generally on the radiological risks. This study highlights the inadequacy of existing deterministic risk assessment methods, which cannot account for the uncertainty and complexity of hazards that workers are exposed to. We instead propose a fuzzy logic based safety assessment model that can analyze and compare alternatives utilizing a step-by-step risk quantification and multidimensional approach. This enables personnel to assess the various risks involved when decontaminating and decommissioning nuclear power plant structures that cannot be quantitatively assessed owing to a lack of data. Our proposed fuzzy based risk assessment model can also be applied to risk assessment in other engineering fields that depend on the judgment of experts supported by little or no statistical data.
Byeol Kim; Joo Sung Lee; Yong Han Ahn. Fuzzy Based Risk Assessment for Decommissioning Concrete Bioshield Structures in Nuclear Power Plants: Structural Risks and Worker Safety. Applied Sciences 2020, 10, 2614 .
AMA StyleByeol Kim, Joo Sung Lee, Yong Han Ahn. Fuzzy Based Risk Assessment for Decommissioning Concrete Bioshield Structures in Nuclear Power Plants: Structural Risks and Worker Safety. Applied Sciences. 2020; 10 (7):2614.
Chicago/Turabian StyleByeol Kim; Joo Sung Lee; Yong Han Ahn. 2020. "Fuzzy Based Risk Assessment for Decommissioning Concrete Bioshield Structures in Nuclear Power Plants: Structural Risks and Worker Safety." Applied Sciences 10, no. 7: 2614.
This paper presents a method to determine an optimal configuration of a teleoperated excavator to minimize the induced undercarriage oscillation for robust end-point stabilization. Treating the excavator as a kinematically redundant system, where non-unique combinations of the undercarriage position and arm posture can locate the end-point at the same reference. A specific configuration can be chosen to not excite undercarriage oscillation with simple end-point error feedback control without model-based or measurement-based vibration suppression. Robust stability measures based on normalized coprime factorization as well as modal decomposition solve the redundancy of the kinematics. An advantage of this approach is that the control engineer can proceed as if the excavator arm is fixed to rigid ground, which is practically not the case, and apply simple traditional Jacobian-based end-point control.
Michael LiBretto; Yong Han Ahn; Chang Soo Han; Yong K. Cho; Jun Ueda. Configuration Optimization for End-Point Stabilization of Redundant Manipulators With Base Flexibility. ASME Letters in Dynamic Systems and Control 2020, 1, 1 -9.
AMA StyleMichael LiBretto, Yong Han Ahn, Chang Soo Han, Yong K. Cho, Jun Ueda. Configuration Optimization for End-Point Stabilization of Redundant Manipulators With Base Flexibility. ASME Letters in Dynamic Systems and Control. 2020; 1 (2):1-9.
Chicago/Turabian StyleMichael LiBretto; Yong Han Ahn; Chang Soo Han; Yong K. Cho; Jun Ueda. 2020. "Configuration Optimization for End-Point Stabilization of Redundant Manipulators With Base Flexibility." ASME Letters in Dynamic Systems and Control 1, no. 2: 1-9.
Many solutions about the teleoperation of unmanned robotic excavators have been studied continuously. However, if excavators that are remotely controlled were employed, the probability of an accident would be higher. For this reason, there have been many ways proposed to attempt to reduce accidents in these dangerous situations. In this paper, a novel methodology will be introduced with a focus on the multiple excavators themselves. The proposed method details how one excavator can be generated or expressed as an obstacle in the Configuration-Space (C-space) with respect to another excavator’s side for collision avoidance each other. This method is based on kinematics information which is measurable and given. Therefore, this method can be used or applied independently by using widely used pose sensors and wireless communication devices. The phase of mathematical derivation about obstacle sets is described in detail. The results are shown in accompanying figures and tables for demonstrating that the proposed method detected the proximity and found the collision-free zone accurately. The proposed system can be powerful when applied to a teleoperation system, where it would be particularly useful and helpful to the operator.
Dongik Sun; Seunghoon Hwang; Byeol Kim; Yonghan Ahn; Joosung Lee; Jeakweon Han. Creation of One Excavator as an Obstacle in C-Space for Collision Avoidance during Remote Control of the Two Excavators Using Pose Sensors. Remote Sensing 2020, 12, 1122 .
AMA StyleDongik Sun, Seunghoon Hwang, Byeol Kim, Yonghan Ahn, Joosung Lee, Jeakweon Han. Creation of One Excavator as an Obstacle in C-Space for Collision Avoidance during Remote Control of the Two Excavators Using Pose Sensors. Remote Sensing. 2020; 12 (7):1122.
Chicago/Turabian StyleDongik Sun; Seunghoon Hwang; Byeol Kim; Yonghan Ahn; Joosung Lee; Jeakweon Han. 2020. "Creation of One Excavator as an Obstacle in C-Space for Collision Avoidance during Remote Control of the Two Excavators Using Pose Sensors." Remote Sensing 12, no. 7: 1122.
This study aimed to assess the defect liability system for repairing various defects during residential buildings’ defect liability period using the loss distribution approach (LDA). It examined 6,087 defect cases from 48 residential buildings in the Republic of Korea between 2008 and 2017 for which defect disputes occurred. The analysis confirmed that damage and water problems were found to be serious defects in the reinforced concrete work, while relatively varied serious defects occurred in the finish work. Specifically, the structure and finish show high-severity/high-frequency characteristics; thus, attention must be paid to their quality control. Deriving the defect cost ratio’s distribution for each defect liability period showed that defect liability bonds must be increased to cover the 2- and 10-year defect liability periods and must be decreased for the 3- and 5-year defect liability periods. A defect classification matrix suitable for different defect liability periods for each country and a defect liability system evaluated using the LDA-based model can provide a basis for reasonably adjusting defect costs among the parties involved in defect disputes.
Sanghyo Lee; Joosung Lee; Yonghan Ahn. LDA-Based Model for Assessing the Defect Liability System in Residential Buildings’ Maintenance Phase. Journal of Performance of Constructed Facilities 2020, 34, 04020007 .
AMA StyleSanghyo Lee, Joosung Lee, Yonghan Ahn. LDA-Based Model for Assessing the Defect Liability System in Residential Buildings’ Maintenance Phase. Journal of Performance of Constructed Facilities. 2020; 34 (2):04020007.
Chicago/Turabian StyleSanghyo Lee; Joosung Lee; Yonghan Ahn. 2020. "LDA-Based Model for Assessing the Defect Liability System in Residential Buildings’ Maintenance Phase." Journal of Performance of Constructed Facilities 34, no. 2: 04020007.
Established by the U.S. Green Building Council (USGBC), the Leadership in Energy and Environmental Design (LEED) became a sustainable leader of green building rating systems in American and many other countries. In Vietnam, LEED is expected as a potential solution in improving the sustainable quality of buildings for residents and solving the housing/infrastructure demand with a limit in resource consumption and minimizing negative environmental impacts. The study analyzed the awarded LEED 2009 credits by investigating the data of 36 of the total 42 LEED BC+D 2009 certified projects in Vietnam. The results of the investigation indicated the awarded credits were significantly implemented in Vietnam. These results were converted based on the summary updated on LEED version 4 of the USGBC report, to become a useful guideline for green building cost-efficiency strategies. Additionally, it also served as reference data for the Vietnamese public agency to update their green regulations based on the specific characteristics of Vietnam.
Duy Hoang Pham; Byeol Kim; Joosung Lee; Abraham Chiwon Ahn; Yonghan Ahn. A Comprehensive Analysis: Sustainable Trends and Awarded LEED 2009 Credits in Vietnam. Sustainability 2020, 12, 852 .
AMA StyleDuy Hoang Pham, Byeol Kim, Joosung Lee, Abraham Chiwon Ahn, Yonghan Ahn. A Comprehensive Analysis: Sustainable Trends and Awarded LEED 2009 Credits in Vietnam. Sustainability. 2020; 12 (3):852.
Chicago/Turabian StyleDuy Hoang Pham; Byeol Kim; Joosung Lee; Abraham Chiwon Ahn; Yonghan Ahn. 2020. "A Comprehensive Analysis: Sustainable Trends and Awarded LEED 2009 Credits in Vietnam." Sustainability 12, no. 3: 852.
This study systematically analyzes various defect patterns that occur during the warranty period of residential buildings using the loss distribution approach (LDA). This paper examines 16,108 defects from 133 residential buildings where defect disputes occurred between 2008 and 2018 in South Korea. The analysis results showed that the defect losses were relatively high in reinforcement concrete (RC) work (3/5/10 years), waterproof work (5 years), and finish work (2 years). It is shown that RC work has a high frequency of defects, such as cracks in concrete in public spaces affected by external factors. In addition, it was analyzed that the type of defect needed high repair cost because the area where the defect—such as incorrect installation and missing task—occurred, needed construction again. According to the level of frequency and severity, losses were divided within four zones to provide detailed strategies (by period). This will effectively contribute to minimizing unnecessary losses from defects as quantifying the losses of defects.
Byeol Kim; Yonghan Ahn; Sanghyo Lee. LDA-Based Model for Defect Management in Residential Buildings. Sustainability 2019, 11, 7201 .
AMA StyleByeol Kim, Yonghan Ahn, Sanghyo Lee. LDA-Based Model for Defect Management in Residential Buildings. Sustainability. 2019; 11 (24):7201.
Chicago/Turabian StyleByeol Kim; Yonghan Ahn; Sanghyo Lee. 2019. "LDA-Based Model for Defect Management in Residential Buildings." Sustainability 11, no. 24: 7201.
Building maintenance is closely related to the performance and sustainability of buildings. However, existing approaches to maintenance are limited in terms of estimating required repairs. Therefore, this study proposes a case-based reasoning (CBR)-based model for estimating the time when the first repair will be needed after the completion of construction, even in phases where maintenance-related information is scarce. CBR and fuzzy-analytic hierarchy process (AHP) were employed as research methodologies. A database was established by collecting 257 cases related to maintenance of apartment buildings, and attributes were extracted through literature reviews and expert interviews. Then, attributes were weighted by fuzzy-AHP and case similarities were computed by measuring the Euclidean distance. Similar cases were retrieved based on similarity scores. The model was validated via a comparison of 20 randomly selected test cases with the output of retrieved cases. The results showed that the average case similarities of 3-, 5-, 7-, and 10-nearest neighbors (NN) were 98.05%, 97.86%, 97.73%, and 97.59%, respectively, and mean absolute percentage errors for 3-, 5-, 7-, and 10-NN were mostly lower than 20%, confirming the applicability of the proposed model. The proposed method will help in the preliminary estimation of the repair time of building components.
Sojin Park; Nahyun Kwon; Yonghan Ahn. Forecasting Repair Schedule for Building Components Based on Case-Based Reasoning and Fuzzy-AHP. Sustainability 2019, 11, 7181 .
AMA StyleSojin Park, Nahyun Kwon, Yonghan Ahn. Forecasting Repair Schedule for Building Components Based on Case-Based Reasoning and Fuzzy-AHP. Sustainability. 2019; 11 (24):7181.
Chicago/Turabian StyleSojin Park; Nahyun Kwon; Yonghan Ahn. 2019. "Forecasting Repair Schedule for Building Components Based on Case-Based Reasoning and Fuzzy-AHP." Sustainability 11, no. 24: 7181.
Of all the machinery and equipment used on construction sites, excavators are responsible for the greatest number of fatal accidents. Excavation is an inherently risky process due to imprecise work processes and the unstable external environment on most work sites. The resulting accidents cause serious injuries that threaten the lives of not only the excavator pilots but also those working around them. In this study, we propose a mechanical device that is capable of operating the excavator remotely from a nearby safe location such as a site office. To ensure worker safety and at the same time boost the productivity of excavation operations, data from 3D scanners, cameras, and sensors were combined to create a detailed 3D picture of the area surrounding the excavation site to guide a remotely operated excavating system. Rather than modifying the excavator itself, a removable manipulator was mounted on the joystick in the excavator’s cockpit. Our proposed system was tested on a standard commercial excavator to verify its performance for a real-world excavation task.
Joosung Lee; Byeol Kim; Dongik Sun; Changsoo Han; Yonghan Ahn. Development of Unmanned Excavator Vehicle System for Performing Dangerous Construction Work. Sensors 2019, 19, 4853 .
AMA StyleJoosung Lee, Byeol Kim, Dongik Sun, Changsoo Han, Yonghan Ahn. Development of Unmanned Excavator Vehicle System for Performing Dangerous Construction Work. Sensors. 2019; 19 (22):4853.
Chicago/Turabian StyleJoosung Lee; Byeol Kim; Dongik Sun; Changsoo Han; Yonghan Ahn. 2019. "Development of Unmanned Excavator Vehicle System for Performing Dangerous Construction Work." Sensors 19, no. 22: 4853.
The latest IT technology integration movements, such as building information modeling (BIM), have engendered changes in the technology and participatory organizations in the construction industry, which have resulted in process innovations and productivity gains. BIM lays the foundation for using a variety of new information that is not applicable to traditional construction methods. Construction companies are applying such information to various analyses, simulations, and learning and education projects to stimulate innovation. In Korea, however, since BIM was introduced in 2008, it has been used in various ways across diverse fields, but its contribution remains minimal. This is due to the inadequate competence level of BIM managers, who emerge from a system incapable of adequately educating BIM managers. In other words, the curriculum has not been able to impart the BIM skills necessary to accommodate the requirements of the industry. Only the most basic BIM modeling course is offered, and even such a course is dependent on external instructors. This creates a gap with the existing construction engineering educational curriculum. This study proposes a BIM-based construction engineering educational curriculum that has not been attempted before to overcome these limitations and generate a BIM workforce to cater to the industry.
Sanghyo Lee; Joosung Lee; Yonghan Ahn. Sustainable BIM-Based Construction Engineering Education Curriculum for Practice-Oriented Training. Sustainability 2019, 11, 6120 .
AMA StyleSanghyo Lee, Joosung Lee, Yonghan Ahn. Sustainable BIM-Based Construction Engineering Education Curriculum for Practice-Oriented Training. Sustainability. 2019; 11 (21):6120.
Chicago/Turabian StyleSanghyo Lee; Joosung Lee; Yonghan Ahn. 2019. "Sustainable BIM-Based Construction Engineering Education Curriculum for Practice-Oriented Training." Sustainability 11, no. 21: 6120.
Sustainable construction addresses both rising housing demand and the need to reduce energy consumption, but is not yet widespread in Vietnam, although the number of Green Building Certified projects has increased significantly since 2015, especially those with LEED certification. Certification adds value to the project but also incurs additional costs and implementation challenges for general contractors (GCs) and other stakeholders. The growing popularity of LEED buildings requires GCs to understand their role in fulfilling the LEED requirements. We therefore conducted a thorough review of the previous research on LEED v4 guidelines and their local equivalents to determine what is expected of GCs working on LEED v4 BD + C projects in Vietnam. A survey of 72 experts, engineers, and architects working in the construction sector identified the LEED tasks where Vietnamese GCs lack experience and suggested solutions to address this shortfall were developed. In particular, Vietnamese GCs lacked experience in implementing their sustainable roles. These results provide a useful foundation for Vietnamese GCs seeking to expand the scope of their LEED work and identified necessary training. Our findings will also guide future research to help GCs in Vietnam adapt to LEED’s sustainability requirements and support sustainable construction in Vietnam.
Duy Hoang Pham; Joosung Lee; Yonghan Ahn. Implementing LEED v4 BD+C Projects in Vietnam: Contributions and Challenges for General Contractor. Sustainability 2019, 11, 5449 .
AMA StyleDuy Hoang Pham, Joosung Lee, Yonghan Ahn. Implementing LEED v4 BD+C Projects in Vietnam: Contributions and Challenges for General Contractor. Sustainability. 2019; 11 (19):5449.
Chicago/Turabian StyleDuy Hoang Pham; Joosung Lee; Yonghan Ahn. 2019. "Implementing LEED v4 BD+C Projects in Vietnam: Contributions and Challenges for General Contractor." Sustainability 11, no. 19: 5449.
In recent decades, building maintenance has been recognized as an important issue as the number of deteriorating buildings increases around the world. In densely populated cities, building maintenance is essential for ensuring sustainable living and safety for residents. Improper maintenance can not only cause enormous maintenance costs, but also negatively affect residents and their environment. As a first step, the service life of building components needs to be estimated in advance. Mechanical, electrical, and plumbing (MEP) components especially produce many maintenance-related problems compared to other components. In this research, a model was developed that applies the genetic algorithm (GA) and case-based reasoning (CBR) methodologies to estimating the service life of MEP components. The applicability of the model was tested by comparing the outputs of 20 randomly selected test cases with those of retrieved similar cases. The experimental results demonstrated that the overall similarity scores of the retrieved cases were over 90%, and the mean absolute error rate (MAER) of 10-NN was approximately 7.48%. This research contributes to the literature for maintenance management by not only presenting an approach to estimating the service life of building components, but also by helping convert the existing maintenance paradigm from reactive to proactive measures.
Nahyun Kwon; Kwonsik Song; Moonseo Park; Youjin Jang; Inseok Yoon; Yonghan Ahn. Preliminary Service Life Estimation Model for MEP Components Using Case-Based Reasoning and Genetic Algorithm. Sustainability 2019, 11, 3074 .
AMA StyleNahyun Kwon, Kwonsik Song, Moonseo Park, Youjin Jang, Inseok Yoon, Yonghan Ahn. Preliminary Service Life Estimation Model for MEP Components Using Case-Based Reasoning and Genetic Algorithm. Sustainability. 2019; 11 (11):3074.
Chicago/Turabian StyleNahyun Kwon; Kwonsik Song; Moonseo Park; Youjin Jang; Inseok Yoon; Yonghan Ahn. 2019. "Preliminary Service Life Estimation Model for MEP Components Using Case-Based Reasoning and Genetic Algorithm." Sustainability 11, no. 11: 3074.
Since the concept of building information modeling (BIM) was introduced in South Korea in 2008, digital fabrication concerning free-form shapes and complex parametric information has been expanding owing to the development of BIM software and tools. However, the digital fabrication process is inadequate in terms of efficiency and productivity because of the need to convert from conventional two-dimensional (2D) drawings to a BIM design; this adversely affects the unified design, fabrication, installation, and inspection processes. Moreover, an optimized process has not been developed thus far because the productivity of digital fabrication has not been quantitatively verified for various projects in the field. This study proposes a BIM-based digital fabrication process for prefabricated parts of buildings. In addition, a productivity analysis method based on the queuing model is proposed using personnel input and performance calculation data to verify productivity. It is expected that the digital fabrication process and productivity analysis model proposed here will be applied to complex digital fabrication works.
Joo-Sung Lee; Nahyun Kwon; Nam-Hyuk Ham; Jae-Jun Kim; Yong-Han Ahn. BIM-Based Digital Fabrication Process for a Free-Form Building Project in South Korea. Advances in Civil Engineering 2019, 2019, 1 -18.
AMA StyleJoo-Sung Lee, Nahyun Kwon, Nam-Hyuk Ham, Jae-Jun Kim, Yong-Han Ahn. BIM-Based Digital Fabrication Process for a Free-Form Building Project in South Korea. Advances in Civil Engineering. 2019; 2019 ():1-18.
Chicago/Turabian StyleJoo-Sung Lee; Nahyun Kwon; Nam-Hyuk Ham; Jae-Jun Kim; Yong-Han Ahn. 2019. "BIM-Based Digital Fabrication Process for a Free-Form Building Project in South Korea." Advances in Civil Engineering 2019, no. : 1-18.
Aims and objectives The aims were to (a) identify how many older people with cognitive impairments are living in modified homes and (b) explore associated factors, and (c) examine the mediating effects that their caregivers’ information needs and perceptions of fall risk and other factors. Background Older people and their informal caregivers may consider implementing home modifications as an effective strategy for fall prevention. However, there is a lack of information on which older people's homes receive modifications and the various factors associated with such modifications among community‐dwelling older people with cognitive impairments. Design This cross‐sectional and correlational study utilises a secondary data analysis. Methods The data for this secondary analysis were taken from the 2015 National Online Survey of Caregivers, which includes information provided by 226 adult caregivers for older people with cognitive impairments. Descriptive analyses, hierarchical binary logistic regression and structural equation modelling were performed based on the Andersen and Newman framework of health services utilisation. Results Overall, 46.5% of the older people lived in modified homes. Older people's impaired activities for daily living (ADLs), caregivers’ information needs and perceptions of fall risk were all associated with home modifications (all p values<0.05). Caregivers’ information needs mediated the relationship between impaired ADLs and home modifications (indirect effect = 0.026, p < 0.05), whereas the caregivers’ perceptions of fall risk did not. Conclusions Older people with both cognitive and functional impairments are more likely to modify their home on behalf of care recipient's staying at home. Caregivers’ information needs should thus be prioritized when considering home modifications to facilitate caring for older people with impaired ADLs. Implication for practice Nurses and other healthcare professionals should be prepared to offer appropriate information and comprehensive assessments of older people's conditions with regard to home modifications.
Heejung Kim; Yunchuan (Lucy) Zhao; Namhee Kim; Yong Han Ahn. Home modifications for older people with cognitive impairments: Mediation analysis of caregivers’ information needs and perceptions of fall risks. International Journal of Older People Nursing 2019, 14, e12240 .
AMA StyleHeejung Kim, Yunchuan (Lucy) Zhao, Namhee Kim, Yong Han Ahn. Home modifications for older people with cognitive impairments: Mediation analysis of caregivers’ information needs and perceptions of fall risks. International Journal of Older People Nursing. 2019; 14 (3):e12240.
Chicago/Turabian StyleHeejung Kim; Yunchuan (Lucy) Zhao; Namhee Kim; Yong Han Ahn. 2019. "Home modifications for older people with cognitive impairments: Mediation analysis of caregivers’ information needs and perceptions of fall risks." International Journal of Older People Nursing 14, no. 3: e12240.