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Dr. SEUNG HYUN CHA
Department of Interior Architecture Design, Hanyang University, Seoul 04763, Republic of Korea

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0 Human Behavior
0 Future Cities
0 Smart Design
0 Digital Twin
0 IOT/AR/VR

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Review
Published: 01 April 2021 in Applied Energy
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In urban environments, decentralized energy systems from renewable photovoltaic resources, clean and available, are gradually replacing conventional energy systems as an attractive source for electricity generation. Especially with the availability of unexploited rooftop areas and the ease of installation, along with technological development and permanent cost reductions of photovoltaic panels. However, the optimal use of these systems requires accurate estimates of supply (rooftop solar photovoltaic potential) and the design of an intelligent distributed-system integrated with power grids. Geographic information systems (GISs)-based estimation is justified as a promising approach for estimating rooftop solar photovoltaic potential, in particular, the possibility of combining GISs with LiDAR (Lighting-Detection-And-Ranging) to build robust approaches leading to accurate estimates of the rooftop solar photovoltaic potential. Accordingly, this study aims to present a comprehensive review of GISs-based rooftop solar photovoltaic potential estimation approaches that have been applied at different scales, including countries. The study classified GISs-based approaches into sampling, geostatistics, modeling, and machine learning. The applications, advantages, and disadvantages of each approach were reviewed and discussed. The results revealed that GISs-based rooftop solar photovoltaic potential estimation approaches, can be applied to the large-scale spatial-temporal assessment of future energy systems with decentralized electrical energy grids. Assessment results can be employed to propose effective-policies for rooftop photovoltaic integration in built environments. However, the development of a new methodology that integrates GISs with machine learning to provide an accurate and less computationally demanding alternative to LiDAR-based approaches, will contribute significantly to large-scale estimates of the solar photovoltaic potential of building rooftops.

ACS Style

Abdo Abdullah Ahmed Gassar; Seung Hyun Cha. Review of geographic information systems-based rooftop solar photovoltaic potential estimation approaches at urban scales. Applied Energy 2021, 291, 116817 .

AMA Style

Abdo Abdullah Ahmed Gassar, Seung Hyun Cha. Review of geographic information systems-based rooftop solar photovoltaic potential estimation approaches at urban scales. Applied Energy. 2021; 291 ():116817.

Chicago/Turabian Style

Abdo Abdullah Ahmed Gassar; Seung Hyun Cha. 2021. "Review of geographic information systems-based rooftop solar photovoltaic potential estimation approaches at urban scales." Applied Energy 291, no. : 116817.

Journal article
Published: 11 February 2021 in Sensors
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An integrated smart home system (ISHS) is an effective way to improve the quality of life of the elderly. The elderly’s willingness is essential to adopt an ISHS; to the best of our knowledge, no study has investigated the elderly’s perception of ISHS. Consequently, this study aims to investigate the elderly’s perception of the ISHS by comprehensively evaluating its possible benefits and negative responses. A set of sensors required for an ISHS was determined, and interviews were designed based on four factors: perceived comfort, perceived usability, perceived privacy, and perceived benefit. Subsequently, technological trials of the sensor-set followed by two focus group interviews were conducted on nine independently living elderly participants at a senior welfare center in South Korea. Consistent with previous studies, the results of this investigation indicate that elderly participants elicited negative responses regarding usability complexity, and discomfort to daily activities. Despite such negative responses, after acquiring enough awareness about the ISHS’s benefits, the elderly acknowledged its necessity and showed a high level of willingness. Furthermore, these results indicate that for a better adoption of an ISHS, sufficient awareness regarding its benefits and development of elderly-friendly smart home sensors that minimize negative responses are required.

ACS Style

Tae Jo; Jae Ma; Seung Cha. Elderly Perception on the Internet of Things-Based Integrated Smart-Home System. Sensors 2021, 21, 1284 .

AMA Style

Tae Jo, Jae Ma, Seung Cha. Elderly Perception on the Internet of Things-Based Integrated Smart-Home System. Sensors. 2021; 21 (4):1284.

Chicago/Turabian Style

Tae Jo; Jae Ma; Seung Cha. 2021. "Elderly Perception on the Internet of Things-Based Integrated Smart-Home System." Sensors 21, no. 4: 1284.

Journal article
Published: 14 December 2020 in Building and Environment
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To plan successful activity-based workplaces (ABW), architects need to clearly understand user-specific activity patterns through the accurate recognition of user activity. Because user activity is closely associated with space, equipment, and users, such diverse activity-related information should be essentially considered for accurate activity recognition. However, previous activity recognition methods have limitations for accurately recognizing user activity for ABW planning, because they only relied on sensor-estimated data and are, therefore, unable to comprehensively consider diverse activity-related information. The study thus integrates site investigation and sensor estimation using a Bluetooth Low Energy beacon and accelerometer for accurately recognizing user activity based on diverse activity-related information. We defined five important items of activity-related information (user actions, number of nearby users, function of space, equipment located in space, and space use policy) and developed a user-specific activity pattern generation (UAPG) framework consisting of three stages: (1) the preparation stage, (2) sensor-estimation stage, and (3) activity pattern generation stage. The demonstration was conducted through scenario-based experiments in an academic office building. In the demonstration, the UAPG framework achieved 91.8% of activity recognition accuracy and successfully generated user-specific activity patterns. In addition, information regarding space usage, proportion of activities, and spatial preference of the user was generated based on a user-specific activity pattern. Such objective information provided by the UAPG framework enables evidence-based ABW planning that efficiently accommodates users with minimal office space, while simultaneously increasing their satisfaction and productivity.

ACS Style

Jae Hoon Ma; Seung Hyun Cha. A user-specific activity pattern generation framework for evidence-based ABW planning. Building and Environment 2020, 189, 107519 .

AMA Style

Jae Hoon Ma, Seung Hyun Cha. A user-specific activity pattern generation framework for evidence-based ABW planning. Building and Environment. 2020; 189 ():107519.

Chicago/Turabian Style

Jae Hoon Ma; Seung Hyun Cha. 2020. "A user-specific activity pattern generation framework for evidence-based ABW planning." Building and Environment 189, no. : 107519.

Journal article
Published: 06 November 2020 in Journal of Computational Design and Engineering
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Although offsite construction (OSC) has emerged as a promising solution to low productivity issues in the construction industry, knowledge for effective management of OSC projects is yet to be explored and developed further. To enhance our understanding of the landscape of the current OSC management knowledge, this study identified and reviewed 83 operation-level OSC management papers. By mapping the papers on three dimensions (i.e. OSC project type, project phase, and management area), this review sheds light on the knowledge areas addressed more frequently than the other areas over time in a detailed manner. The review also shows that papers on planning, manufacturing, maintenance phases and schedule, resources, and stakeholder management areas have a relatively large number of citations, implying a great interest in these research areas. Finally, the review discusses that substantial research work is still required in the areas of OSC execution strategy, emerging technologies in offsite manufacturing and schedule management, internet of things (IoT)-based material logistics planning and tracking, building information model-based visualization and decision support, and social and environmental effects of stakeholder engagement in OSC projects.

ACS Style

Junyoung Jang; Seungjun Ahn; Seung Hyun Cha; Kyeongwoon Cho; Choongwan Koo; Tae Wan Kim. Toward productivity in future construction: mapping knowledge and finding insights for achieving successful offsite construction projects. Journal of Computational Design and Engineering 2020, 8, 1 -14.

AMA Style

Junyoung Jang, Seungjun Ahn, Seung Hyun Cha, Kyeongwoon Cho, Choongwan Koo, Tae Wan Kim. Toward productivity in future construction: mapping knowledge and finding insights for achieving successful offsite construction projects. Journal of Computational Design and Engineering. 2020; 8 (1):1-14.

Chicago/Turabian Style

Junyoung Jang; Seungjun Ahn; Seung Hyun Cha; Kyeongwoon Cho; Choongwan Koo; Tae Wan Kim. 2020. "Toward productivity in future construction: mapping knowledge and finding insights for achieving successful offsite construction projects." Journal of Computational Design and Engineering 8, no. 1: 1-14.

Article
Published: 09 August 2020 in Journal of Interior Design
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The purpose of this study was to investigate the effects of interior color schemes in immersive virtual environments (IVEs) on emotion, task performance, and heart rate to examine IVEs' potential for interior color research. Fifty‐five (n = 55) student participants were recruited to experience four different colored IVE models (i.e., red, green, blue, and white), and their emotions, heart rate change, and proofreading performances during the immersion were measured. Participants were also asked about their sense of presence after the experience. The findings support the following three hypotheses: (1) IVE interior color schemes affect subject emotion, (2) IVE interior color schemes affect subject task performance as measured through a proofreading exercise, and (3) IVE interior color schemes affect subject heart rate. Specifically, red was perceived as significantly heavier, warmer, more exciting, tenser, and unpleasant. Significantly fewer errors occurred during the white immersion versus the green color scheme when completing the task performance exercise. While heart rate was reduced for each color, significant decreases were detected in the blue, white, and green color scenarios. The majority of participants felt a sense of being there when experiencing the four colored IVE spaces. Based on these results, we conclude that IVE has potential for interior color research to overcome the limitations of traditional color research tools.

ACS Style

Seung Hyun Cha; Shaojie Zhang; Tae Wan Kim. Effects of Interior Color Schemes on Emotion, Task Performance, and Heart Rate in Immersive Virtual Environments. Journal of Interior Design 2020, 45, 51 -65.

AMA Style

Seung Hyun Cha, Shaojie Zhang, Tae Wan Kim. Effects of Interior Color Schemes on Emotion, Task Performance, and Heart Rate in Immersive Virtual Environments. Journal of Interior Design. 2020; 45 (4):51-65.

Chicago/Turabian Style

Seung Hyun Cha; Shaojie Zhang; Tae Wan Kim. 2020. "Effects of Interior Color Schemes on Emotion, Task Performance, and Heart Rate in Immersive Virtual Environments." Journal of Interior Design 45, no. 4: 51-65.

Journal article
Published: 22 July 2020 in Automation in Construction
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Accurate face-to-face interaction estimation is required for a successful data-driven design in workplaces. In previous studies, various sensor-based interaction estimation methods which use proximity and speaking data have been developed. However, these data alone cannot confirm the presence of interactions because non-interacting users also engage in speaking activities. This study aims to develop a novel turn-taking pattern-based interaction estimation (i.e., TIE) framework that integrates turn-taking with location data. The framework estimates interactions in three steps: 1) co-location estimation using a Bluetooth Low Energy beacon; 2) speaking-turn ascertainment through volume-based speaker identification; and 3) interaction group recognition based on turn-taking pattern analysis. Using three different experimental scenarios, the interaction estimation accuracy of the framework was demonstrated to be 77.7%. In the absence of co-location estimation errors, the interaction estimation accuracy increases to 95.5%. The demonstration results indicate that the TIE framework has potential for accurate interaction estimation in workplaces.

ACS Style

Jae Hoon Ma; Seung Hyun Cha. A human data-driven interaction estimation using IoT sensors for workplace design. Automation in Construction 2020, 119, 103352 .

AMA Style

Jae Hoon Ma, Seung Hyun Cha. A human data-driven interaction estimation using IoT sensors for workplace design. Automation in Construction. 2020; 119 ():103352.

Chicago/Turabian Style

Jae Hoon Ma; Seung Hyun Cha. 2020. "A human data-driven interaction estimation using IoT sensors for workplace design." Automation in Construction 119, no. : 103352.

Review
Published: 20 June 2020 in Energy and Buildings
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Building energy prediction techniques are the primary tool for moving towards sustainable built environments. Energy prediction models play irreplaceable roles in making energy policy and the development of the building sector. This paper presents a comprehensive review of the prevailing prediction techniques used in large-scale building energy applications under different scopes and different archetypes, including black-box, white-box, and grey-box based methods. Additionally, the advantages and disadvantages of the applications of those approaches are compared and discussed in the context of large-scale buildings. The review results show that prediction techniques have addressed a variety of large-scale building energy related-applications, such as energy consumption forecasting and prediction, energy consumption profiling, energy mapping and benchmarking of buildings. However, there are still some research gaps that require more attention such as the inclusion of occupant behavior in white-box based models and the explicit representation of end-uses in black-box based models. Significantly, this review concludes with a few key tasks for modification of the current prediction approach framework, which can help with forecasting future energy use changes of specific buildings during the retrofit process or inclusion of renewable energy technology. This would assist in developing an appropriate strategy for the sustainability of the built environment.

ACS Style

Abdo Abdullah Ahmed Gassar; Seung Hyun Cha. Energy prediction techniques for large-scale buildings towards a sustainable built environment: A review. Energy and Buildings 2020, 224, 110238 .

AMA Style

Abdo Abdullah Ahmed Gassar, Seung Hyun Cha. Energy prediction techniques for large-scale buildings towards a sustainable built environment: A review. Energy and Buildings. 2020; 224 ():110238.

Chicago/Turabian Style

Abdo Abdullah Ahmed Gassar; Seung Hyun Cha. 2020. "Energy prediction techniques for large-scale buildings towards a sustainable built environment: A review." Energy and Buildings 224, no. : 110238.

Journal article
Published: 07 May 2020 in Renewable and Sustainable Energy Reviews
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Since a traditional centralized control system (e.g., building energy management system) with a fixed schedule and manual control is not appropriate to irregularly occupied rooms, it is expected to have a large amount of energy saving potential in operating the HVAC system. To overcome this challenge, this study aimed to develop a novel operation approach for the energy efficiency improvement of the HVAC system in office spaces. The real-time indoor environmental indicators were collected and analyzed to evaluate the current operation status of the HVAC system as well as to propose a novel control strategy in two ways. The significant findings can be illustrated as follows. First, it could be stated that occupants would tend to establish a lower set-point temperature for a cooler indoor environment. To solve this issue, a basic control strategy was proposed to detect the anomaly detection of the HVAC system and to automatically adjust the indoor temperature within a preferred range. Second, it could be evaluated that the HVAC system would be kept operating since occupants would forget to turn off the HVAC system after the meetings. To solve this issue, an advanced control strategy was proposed to operate the automatic on/off control of the HVAC system by considering the indoor temperature and CO2 concentration in real time. The proposed strategies can contribute to a large amount of energy savings in operating the HVAC system of irregularly occupied spaces.

ACS Style

Wenzhuo Li; Choongwan Koo; Taehoon Hong; Jeongyoon Oh; Seung Hyun Cha; Shengwei Wang. A novel operation approach for the energy efficiency improvement of the HVAC system in office spaces through real-time big data analytics. Renewable and Sustainable Energy Reviews 2020, 127, 109885 .

AMA Style

Wenzhuo Li, Choongwan Koo, Taehoon Hong, Jeongyoon Oh, Seung Hyun Cha, Shengwei Wang. A novel operation approach for the energy efficiency improvement of the HVAC system in office spaces through real-time big data analytics. Renewable and Sustainable Energy Reviews. 2020; 127 ():109885.

Chicago/Turabian Style

Wenzhuo Li; Choongwan Koo; Taehoon Hong; Jeongyoon Oh; Seung Hyun Cha; Shengwei Wang. 2020. "A novel operation approach for the energy efficiency improvement of the HVAC system in office spaces through real-time big data analytics." Renewable and Sustainable Energy Reviews 127, no. : 109885.

Erratum
Published: 25 April 2020 in Renewable Energy
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ACS Style

Choongwan Koo; Wenzhuo Li; Seung Hyun Cha; Shaojie Zhang. Corrigendum to “A novel estimation approach for the solar radiation potential with its complex spatial pattern via machine-learning techniques” [Renew. Energy 133 (2019) 575–592]. Renewable Energy 2020, 156, 1389 -1394.

AMA Style

Choongwan Koo, Wenzhuo Li, Seung Hyun Cha, Shaojie Zhang. Corrigendum to “A novel estimation approach for the solar radiation potential with its complex spatial pattern via machine-learning techniques” [Renew. Energy 133 (2019) 575–592]. Renewable Energy. 2020; 156 ():1389-1394.

Chicago/Turabian Style

Choongwan Koo; Wenzhuo Li; Seung Hyun Cha; Shaojie Zhang. 2020. "Corrigendum to “A novel estimation approach for the solar radiation potential with its complex spatial pattern via machine-learning techniques” [Renew. Energy 133 (2019) 575–592]." Renewable Energy 156, no. : 1389-1394.

Erratum
Published: 17 January 2020 in KSCE Journal of Civil Engineering
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This erratum is published to notify a correction in figure 1 and the addition of a citation, Du et al. 2016. See the corrected version below:

ACS Style

Ali Abbas; Minji Choi; Joonoh Seo; Seung Hyun Cha; Heng Li. Erratum to: Effectiveness of Immersive Virtual Reality-Based Communication for Construction Projects. KSCE Journal of Civil Engineering 2020, 24, 691 -692.

AMA Style

Ali Abbas, Minji Choi, Joonoh Seo, Seung Hyun Cha, Heng Li. Erratum to: Effectiveness of Immersive Virtual Reality-Based Communication for Construction Projects. KSCE Journal of Civil Engineering. 2020; 24 (2):691-692.

Chicago/Turabian Style

Ali Abbas; Minji Choi; Joonoh Seo; Seung Hyun Cha; Heng Li. 2020. "Erratum to: Effectiveness of Immersive Virtual Reality-Based Communication for Construction Projects." KSCE Journal of Civil Engineering 24, no. 2: 691-692.

Construction management
Published: 05 November 2019 in KSCE Journal of Civil Engineering
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Though computer-mediated communication technologies such as immersive virtual reality (IVR) have recently shown considerable promise, their effectiveness as methods of communication among the participants in construction projects has yet to be systematically investigated. This study helps fill this gap via a detailed comparison of traditional face-to-face (FtF) discussion of Building Information Modeling (BIM) information displayed on a monitor screen against IVR-based communication with BIM information embedded in the immersive environment. The results of experiments in which groups of participants discussed and chose optimal design options indicated that there is no large statistical difference in IVR-based and FtF communication in terms of discussion quality (level of effectiveness and satisfaction experienced), communication richness (detailed responses and vivid messages), and openness (enjoyableness and open-mindedness) during the communication. However, for the accuracy of communication (information communicated correctly and understood properly), FtF communication was better than IVR-based communication, which is assumed due to weak human-human to interaction in IVR. In addition, the communication appropriateness (behavioral acts such as politeness or social norms), IVR-based communication was significantly less than FtF communication, indicating that communicating with others only seeing virtual avatar could make it difficult to discern participant’ reactions or identify appropriate moments to speak. These results could confirm certain advantages of adopting IVR-based communication while further improvement for real-like interaction between people needs to be made for more effective use of IVR communication.

ACS Style

Ali Abbas; Minji Choi; Joonoh Seo; Seung Hyun Cha; Heng Li. Effectiveness of Immersive Virtual Reality-based Communication for Construction Projects. KSCE Journal of Civil Engineering 2019, 23, 4972 -4983.

AMA Style

Ali Abbas, Minji Choi, Joonoh Seo, Seung Hyun Cha, Heng Li. Effectiveness of Immersive Virtual Reality-based Communication for Construction Projects. KSCE Journal of Civil Engineering. 2019; 23 (12):4972-4983.

Chicago/Turabian Style

Ali Abbas; Minji Choi; Joonoh Seo; Seung Hyun Cha; Heng Li. 2019. "Effectiveness of Immersive Virtual Reality-based Communication for Construction Projects." KSCE Journal of Civil Engineering 23, no. 12: 4972-4983.

Journal article
Published: 01 October 2019 in Building and Environment
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ACS Style

Seung Hyun Cha; Choongwan Koo; Tae Wan Kim; Taehoon Hong. Spatial perception of ceiling height and type variation in immersive virtual environments. Building and Environment 2019, 163, 1 .

AMA Style

Seung Hyun Cha, Choongwan Koo, Tae Wan Kim, Taehoon Hong. Spatial perception of ceiling height and type variation in immersive virtual environments. Building and Environment. 2019; 163 ():1.

Chicago/Turabian Style

Seung Hyun Cha; Choongwan Koo; Tae Wan Kim; Taehoon Hong. 2019. "Spatial perception of ceiling height and type variation in immersive virtual environments." Building and Environment 163, no. : 1.

Journal article
Published: 22 August 2019 in Applied Thermal Engineering
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The present study experimentally investigated thermal characteristics of a double-pipe heat exchanger fitted with perforated self-rotating twisted tapes with six perforation ratios of 0%, 1.16%, 3.63%, 6.46%, 10.1% and 14.49%. The experimental results showed that perforation ratio significantly affects the initial stage of rotation behavior and rotational speed. Perforated self-rotating twisted tapes were experimentally shown to perform greater thermal performance than perforated stationary twisted tapes. In addition, the increase in perforation ratios raised the Nusselt number and pressure drop. Higher thermal performance factor of PR=10.1% than PR=14.49% under rotating condition could be found. When the self-rotating twisted tapes varied from stationary to rotating condition, it is observed that thermal performance factor increased from 0.862 to 0.924, 0.987 to 1.025, 1.04 to 1.078, 1.084 to 1.101, and 1.042 to 1.055, for perforation ratios of 0%, 1.16%, 3.63%, 6.46%, and 10.1%, respectively. Finally, some correlations associated with perforation ratios were established to predict Nusselt number and friction factor, and perforated self-rotating twisted tapes were compared with perforated twisted tapes in terms of thermal performance factor. The optimal design of perforated self-rotating twisted tapes with proper perforated ratio could be offered for industrial application based on thermal performance evaluation.

ACS Style

Shaojie Zhang; Lin Lu; Chuanshuai Dong; Seung Hyun Cha. Thermal characteristics of perforated self-rotating twisted tapes in a double-pipe heat exchanger. Applied Thermal Engineering 2019, 162, 114296 .

AMA Style

Shaojie Zhang, Lin Lu, Chuanshuai Dong, Seung Hyun Cha. Thermal characteristics of perforated self-rotating twisted tapes in a double-pipe heat exchanger. Applied Thermal Engineering. 2019; 162 ():114296.

Chicago/Turabian Style

Shaojie Zhang; Lin Lu; Chuanshuai Dong; Seung Hyun Cha. 2019. "Thermal characteristics of perforated self-rotating twisted tapes in a double-pipe heat exchanger." Applied Thermal Engineering 162, no. : 114296.

Journal article
Published: 17 May 2019 in Applied Thermal Engineering
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This study presents heat transfer and frication factor characteristics of heat exchanger tube with self-rotating twisted tapes (SRTTs). A comparison of SRTTs and stationary twisted tapes (STTs) as well as an examination of the effects of SRTTs with different twist ratios (Y = 2.2, 3, 4, and 6) on the thermal characteristics were experimentally investigated under turbulence flows (12000 < Re < 45000). The experimental results showed that SRTTs under rotating conditions could enhance the thermal performance of heat exchanger as compared with STTs. The twist ratios were found to have less effect on the initial stages of the rotating behavior, and the SRTTs with lower twisted ratios rotated faster under the same operating conditions. In addition, it was observed that the Nusselt number, pressure drop, and thermal performance factor increased with decreasing twist ratios. The maximum thermal performance factors of 1.03, 0.9444, 0.924, and 0.898 could be achieved at the start of rotating behavior for Y = 2.2, 3, 4, and 6, respectively. Finally, some correlations of the Nusselt number and frication factor were established within ±10% deviation of the experimental data.

ACS Style

Shaojie Zhang; Lin Lu; Chuanshuai Dong; Seung Hyun Cha. Performance evaluation of a double-pipe heat exchanger fitted with self-rotating twisted tapes. Applied Thermal Engineering 2019, 158, 113770 .

AMA Style

Shaojie Zhang, Lin Lu, Chuanshuai Dong, Seung Hyun Cha. Performance evaluation of a double-pipe heat exchanger fitted with self-rotating twisted tapes. Applied Thermal Engineering. 2019; 158 ():113770.

Chicago/Turabian Style

Shaojie Zhang; Lin Lu; Chuanshuai Dong; Seung Hyun Cha. 2019. "Performance evaluation of a double-pipe heat exchanger fitted with self-rotating twisted tapes." Applied Thermal Engineering 158, no. : 113770.

Journal article
Published: 10 May 2019 in Building and Environment
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Understanding occupant activities in a building is essential for building management systems to provide occupants with comfort and intelligent indoor environment. However, current occupant activity recognition mainly focuses on individual activity. Group activity recognition indoors has gained little attention, but remains of paramount importance, such as working together, taking classes, and discussions. In this paper, we propose a framework for group activity detection and recognition (i.e., GADAR framework) using smartphone sensors and Bluetooth beacons data. This framework consists of the following four layers: user layer, data package layer, processing layer, and output layer. As individuals within the group show similarity in motion, audio, and proximity, such similarity values are calculated and clustered into groups using hierarchical clustering. The framework then extracts the role, motion, speaking and location features from the clustered groups to distinguish different group activities. Decision tree classifier was selected to recognize the group activity that the group is engaged in. An experiment was conducted to identify the following three common group activities: taking class, seminar, and discussion. The result shows that the proposed GADAR framework could provide more than 89% accuracy in group detection and 89% accuracy in recognizing group activity.

ACS Style

Hao Chen; Seung Hyun Cha; Tae Wan Kim. A framework for group activity detection and recognition using smartphone sensors and beacons. Building and Environment 2019, 158, 205 -216.

AMA Style

Hao Chen, Seung Hyun Cha, Tae Wan Kim. A framework for group activity detection and recognition using smartphone sensors and beacons. Building and Environment. 2019; 158 ():205-216.

Chicago/Turabian Style

Hao Chen; Seung Hyun Cha; Tae Wan Kim. 2019. "A framework for group activity detection and recognition using smartphone sensors and beacons." Building and Environment 158, no. : 205-216.

Journal article
Published: 01 February 2019 in Energy Procedia
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This study proposes a conceptual framework for the real-time monitoring and diagnostic system for the optimal operation of smart building, focusing on the energy-efficient, occupant-oriented, and comfortable indoor environment. The proposed framework aims to improve the energy efficiency in a room of building while achieving the healthy and comfortable indoor environmental quality and occupants’ satisfaction. The proposed framework consists of a three-phase cyclic process (i.e. monitoring, diagnostic, and intervention), and it can be simply replicated and extensively applied to the different levels of physical entities (spatial scalability) in the different time resolutions in the whole life cycle processes (temporal scalability). To elaborate the feasibility of the proposed framework, the Hotel ICON in Hong Kong are chosen as a case study. For three rooms in the Hotel ICON, several sensors are installed for monitoring the energy efficiency and indoor environmental quality in real time. With the collected dataset, it is planned to carry out the diagnostic process (e.g. anomaly detection, time-series analysis, and occupancy schedule pattern analysis) and the intervention process (e.g. automatic control, occupant behaviour change, and optimal operation). The conceptual framework provides a standardized and systematic research approach toward a big picture of an intelligent building systems for the energy-efficient, occupant-oriented, and comfortable indoor environment.

ACS Style

Wenzhuo Li; Choongwan Koo; Seung Hyun Cha; Joseph H.K. Lai; Jinsoo Lee. A conceptual framework for the real-time monitoring and diagnostic system for the optimal operation of smart building: A case study in Hotel ICON of Hong Kong. Energy Procedia 2019, 158, 3107 -3112.

AMA Style

Wenzhuo Li, Choongwan Koo, Seung Hyun Cha, Joseph H.K. Lai, Jinsoo Lee. A conceptual framework for the real-time monitoring and diagnostic system for the optimal operation of smart building: A case study in Hotel ICON of Hong Kong. Energy Procedia. 2019; 158 ():3107-3112.

Chicago/Turabian Style

Wenzhuo Li; Choongwan Koo; Seung Hyun Cha; Joseph H.K. Lai; Jinsoo Lee. 2019. "A conceptual framework for the real-time monitoring and diagnostic system for the optimal operation of smart building: A case study in Hotel ICON of Hong Kong." Energy Procedia 158, no. : 3107-3112.

Articles
Published: 08 January 2019 in Architectural Science Review
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This empirical study sought to validate the spatial-choice modelling approach to user simulation. This validation is challenging, because spatial-choice behaviour is difficult to observe in real-life settings. To overcome this challenge, the study assembled 1137 activity cases from time-use diaries kept by university students and then extracted 74 space-rejection cases (i.e. events when students were unable to take up a particular space-option and so moved to another one). We assessed the attributes of the space-options in the rejection cases by means of a site investigation, predicted space-use probabilities using spatial-choice models, and assessed forecasting accuracy by a Brier score. The spatial-choice models scored 0.35, demonstrating higher forecasting accuracy than two alternative methods, namely space-use analysis (0.50) and the closest distance method (0.84). This study contributes to user simulation by validating the accuracy of the spatial-choice models based on revealed spatial-choice data in real-life settings and comparing it with other methods.

ACS Style

Tae Wan Kim; Seung Hyun Cha. Empirical validation of the spatial-choice modelling approach to user simulation. Architectural Science Review 2019, 62, 313 -322.

AMA Style

Tae Wan Kim, Seung Hyun Cha. Empirical validation of the spatial-choice modelling approach to user simulation. Architectural Science Review. 2019; 62 (4):313-322.

Chicago/Turabian Style

Tae Wan Kim; Seung Hyun Cha. 2019. "Empirical validation of the spatial-choice modelling approach to user simulation." Architectural Science Review 62, no. 4: 313-322.

Journal article
Published: 13 December 2018 in Building and Environment
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For successful implementation of the New Ways of Working (NWW) office, it is necessary to plan on the basis of user-identified space usage information. Of the different methods, a trilateration-based Bluetooth low-energy (BLE) Beacon system has a greater potential as it provides specific location information. However, the feasibility of implementing a trilateration-based BLE Beacon system has not yet been validated in space-usage analysis in the NWW office. The present study thus aimed to establish whether such a system would be suitable for the purpose. Two sets of experiments were performed in an open-plan office in order to evaluate system accuracy. The present study used two indexes: Distance Difference (DD) and Accuracy Rate of User-Identified Location Estimation (AR). The best average DD was 0.7 m at desk 5 in the first experiment, which is promising. However, the overall experimental DDs were 1.63m and 1.93m, while both DD and AR showed significant variance between desks. These findings indicate that system accuracy and consistency are not yet sufficient for space usage analysis in the NWW office. Accordingly, to enhance system accuracy and consistency it will be essential to develop strategies for optimal system deployment and to combine them with other methods.

ACS Style

Seung Hyo Baek; Seung Hyun Cha. The trilateration-based BLE Beacon system for analyzing user-identified space usage of New Ways of Working offices. Building and Environment 2018, 149, 264 -274.

AMA Style

Seung Hyo Baek, Seung Hyun Cha. The trilateration-based BLE Beacon system for analyzing user-identified space usage of New Ways of Working offices. Building and Environment. 2018; 149 ():264-274.

Chicago/Turabian Style

Seung Hyo Baek; Seung Hyun Cha. 2018. "The trilateration-based BLE Beacon system for analyzing user-identified space usage of New Ways of Working offices." Building and Environment 149, no. : 264-274.

Journal article
Published: 13 October 2018 in Renewable Energy
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As a clean and sustainable energy resource with lower environmental impact, the Chinese government encourages the application of solar energy system. The global solar radiation on the horizontal surface in the specific site should be investigated in advance so that the solar energy system could be implemented properly and efficiently. However, the monthly average daily solar radiation (MADSR) in China has complex spatial patterns, and its observation stations are still lacking due to the high cost of equipment. To address these challenges, this study aimed to develop a novel estimation approach for the MADSR with its complex spatial pattern over a vast area in China via machine-learning techniques (i.e. a clustering method (k-means) and an advanced case-based reasoning (A-CBR) model). The MADSR and the relevant information were collected from 97 cities in China for 10 years (from 2006 to 2015). The average prediction accuracy of the proposed approach was determined at 93.23%, showing a promising way. The proposed novel approach is expected to be generalized via the interpolation methods (e.g. kriging method in a geographical information system) so that decision-makers (e.g. construction manager or facility manager) can determine the appropriate location, size and form in implementing the solar energy system.

ACS Style

Choongwan Koo; Wenzhuo Li; Seung Hyun Cha; Shaojie Zhang. A novel estimation approach for the solar radiation potential with its complex spatial pattern via machine-learning techniques. Renewable Energy 2018, 133, 575 -592.

AMA Style

Choongwan Koo, Wenzhuo Li, Seung Hyun Cha, Shaojie Zhang. A novel estimation approach for the solar radiation potential with its complex spatial pattern via machine-learning techniques. Renewable Energy. 2018; 133 ():575-592.

Chicago/Turabian Style

Choongwan Koo; Wenzhuo Li; Seung Hyun Cha; Shaojie Zhang. 2018. "A novel estimation approach for the solar radiation potential with its complex spatial pattern via machine-learning techniques." Renewable Energy 133, no. : 575-592.

Journal article
Published: 01 September 2018 in Automation in Construction
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ACS Style

Seung Hyun Cha; Koen Steemers; Tae Wan Kim. Modeling space preferences for accurate occupancy prediction during the design phase. Automation in Construction 2018, 93, 135 -147.

AMA Style

Seung Hyun Cha, Koen Steemers, Tae Wan Kim. Modeling space preferences for accurate occupancy prediction during the design phase. Automation in Construction. 2018; 93 ():135-147.

Chicago/Turabian Style

Seung Hyun Cha; Koen Steemers; Tae Wan Kim. 2018. "Modeling space preferences for accurate occupancy prediction during the design phase." Automation in Construction 93, no. : 135-147.