• Article

    Analysis of Energy Consumption By End-Use Based on Measurement Data of Low-Density Multi-Family Housing Complex

    저밀 집합 주거단지의 실측자료에 기반한 용도별 에너지 사용량 분석 연구

    Lee Ru-Da ・ Yoon Jong-Ho ・ Kim Dong-Su

    이루다, 윤종호, 김동수

    Although building energy analysis tools, such as ECO2, are essential for architects and building engineers for energy performance analysis, these tools do ... + READ MORE
    Although building energy analysis tools, such as ECO2, are essential for architects and building engineers for energy performance analysis, these tools do not consider various load patterns, including plug loads, for determining the certification level for domestic zero energy. However, in reality, various load patterns can occur, and significant plug loads can be used in buildings. Therefore, in this study, we conducted a detailed analysis of the annual energy consumption of 60 households based on their end-use energy consumption to capture various demand trends in a low-density, multi-family housing complex. While all residential buildings in the complex were of the same size, they showed different occupancy patterns. Based on the actual measurement data, the energy consumed by each energy component through activities such as heating, cooling, hot water supply, ventilation, lighting, and plug load, was analyzed in detail, and three representative load patterns were investigated by calculating the maximum, heavy, and light loads. Furthermore, the estimated energy independence rate was calculated based on the existence of the plug loads of the three representative load patterns. - COLLAPSE
    June 2021
  • Article

    Error Impacts of Time-Lag on In-situ Measurement of Thermal Bridge Performance : Case in the Window-Wall Junction

    현장 열교 측정을 위한 시간지연의 오차영향 평가 연구: 창호-벽체 접합부를 중심으로

    Kang Eun-Ho ・ Kim Dong-Soo ・ Lee Hyo-Mun ・ Yoon Jong-Ho

    강은호, 김동수, 이효문, 윤종호

    Considering the values acquired from thermal bridge performance indicators developed based on a design stage may differ from the actual thermal bridge ... + READ MORE
    Considering the values acquired from thermal bridge performance indicators developed based on a design stage may differ from the actual thermal bridge performance values, it is essential to quantitatively assess their performance in-situ. When the surface temperature of the internal walls of a thermal bridge is measured in-situ to evaluate the performance, a time delay is observed in the transfer of the effect of external conditions to the internal surfaces. The shape of the thermal bridge components exhibit either 2D or 3D boundary conditions, and hence, multiple time lags can occur depending on the surface condition of the thermal bridge, which affects the accuracy of the performance of thermal bridges during evaluations in-situ. Therefore, in this study, we analyzed the effect of time lag of the thermal bridge components on the thermal bridge performance using heat transfer simulations. It was observed that the relative error was approximately 25.35% with an average of 9.22% as compared to the steady-state thermal bridge. Furthermore, the approximate time lag values of each component surface were calculated based on their surface temperatures. As a result, the time lag difference between the thermal and non-thermal bridge components was approximately 10 h and 30 min, respectively. On eliminating the time lag difference from all surfaces of the thermal bridge components using the calculated time lag, the relative error decreased to 19.97% with an average of 7.69%, as compared to the steady-state thermal bridge. Therefore, the relative error increased by 1.53% with an average of approximately 5.40%, owing to the time lag of the thermal bridge. - COLLAPSE
    June 2021
  • Article

    Potential Impact of BIPV Installation Capacity on Energy Self-Sufficiency Rate in Apartment Complex

    BIPV 설치 용량에 따른 아파트 단지 에너지 자립률 분석

    Lee Sang-Yoon ・ Lee Ru-Da ・ Yoon Jong-Ho ・ Kim Dong-Su

    이상윤, 이루다, 윤종호, 김동수

    Photovoltaic (PV) modules are used worldwide in building integrated photovoltaic (BIPV) applications due to the easy installation, maintenance, and on-site power generation ... + READ MORE
    Photovoltaic (PV) modules are used worldwide in building integrated photovoltaic (BIPV) applications due to the easy installation, maintenance, and on-site power generation capabilities. Additionally, PV modules installed on vertical facades and roofs of apartments also facilitate energy reductions in apartment complexes and their units. Although many studies have investigated the effective installation methods of PV systems, the lack of BIPV applications persists, considering BIPV designs have been adopted for buildings by designers and engineers. Therefore, in this study, we investigated the significance of PV power generation in apartment complexes located in Daejeon, South Korea, based on surveyed and simulated data. Actual apartment complexes and each building’s exterior surfaces having solar access were surveyed. Based on the details of the survey, a simulation model was developed using Ecotect and EnergyPlus software tools. For the analysis, the shading effects on the surfaces were first analyzed with Ecotect, followed by a detailed analysis of the simulated PV power generation to determine whether each apartment unit and its complexes could potentially reduce energy. The actual energy usage based on the survey data was obtained from the K-apt website, which is a website handled by the Korean government that provides an energy usage database. This study assumed that the range of installed PV capacities would be between 0.3 kWp and 2 kWp for each apartment unit. The results of this study indicated that the PV power generation depended on the PV installation scenario, i.e., the PV angles and azimuth angle, as well as the shading impact on each PV module surface, could potentially affect the overall energy self-sufficiency rates of the complex, according to apartment deployments. - COLLAPSE
    June 2021
  • Article

    A Study of Inverted Structure Polymer Solar Cell using ZnO with Low Temperature Process

    저온공정 ZnO 적용에 따른 역구조 고분자 태양전지 소자 성능 연구

    Jeon Jae-Min ・ Shin Dong-Yeol ・ Jeong Woo-Jin ・ Kwak Hee-Jung ・ Kim Jun-Young

    전재민, 신동열, 정우진, 곽희정, 김준영

    Recently, active research is being conducted on polymer solar cells to improve power conversion efficiency by developing new device structures, synthesizing polymer ... + READ MORE
    Recently, active research is being conducted on polymer solar cells to improve power conversion efficiency by developing new device structures, synthesizing polymer materials, and applying them to charge extraction layers. In this study, we analyzed the influence of ZnO on the performance of solar cells by using various ZnO thin films (using the high and low temperature sol-gel processes and the nanoparticle process) as an electron extraction layer in inverted polymer solar cells based on PBDB-T:ITIC. The ZnO thin film was formed by the high-temperature (450°C) sol-gel process, which resulted in an increase in the sheet resistance of the ITO electrode by five times. As a result, the power conversion efficiency of the polymer solar cells was low (4.12%). Conversely, in the nanoparticle process, butanol-based ZnO exhibited better dispersion and surface properties than the IPA-based ZnO, resulting in improved performance of the polymer solar cell (PCE of 6.35% and 4.58% with butanol and IPA-based ZnO, respectively). Additionally, a ZnO precursor solution was developed using the low-temperature (150°C) sol-gel process, which was applied as an electron extraction layer in an inverted polymer solar cell. Consequently, the device performance significantly improved (PCE of 8.89%)due to the formation of a ripple-shaped surface, which facilitated the extraction of electrons due to the excellent surface roughness. - COLLAPSE
    June 2021
  • Article

    A Study on the Analysis of Optimal Operating Conditions of AHU System Using Air Heat Source of Air-Type BIPVT Collector

    공기식 BIPVT 컬렉터의 공기 열원을 활용한 AHU 시스템의 최적 운전 조건 분석 연구

    Moon Hyung-Bin ・ Yu Ji-Suk ・ Kim Jin-Hee ・ Kim Jun-Tae

    문형빈, 유지숙, 김진희, 김준태

    A building integrated photovoltaic thermal (BIPVT) system is a complex technology that produces electricity and heat simultaneously. The thermal media in BIPVT ... + READ MORE
    A building integrated photovoltaic thermal (BIPVT) system is a complex technology that produces electricity and heat simultaneously. The thermal media in BIPVT only uses heated air as an energy source for heating and cooling without other facilities such as fans, which facilitates the building construction process and reduces damages to the system due to freezing or leakage. The use of an air handling unit (AHU) system connected to an air-type BIPVT collector reduces the heating load on the building scale. Thereby reducing the energy used within the building. Furthermore, to reduce the heating load of a building effectively, the heated air from the air-type BIPVT collector and outdoor air must be mixed in an appropriate proportion. Therefore, in this study, an AHU system combined with an air-type BIPVT collector is investigated to analyze the optimal operating conditions, by setting the ratio of the preheated air and outdoor air entering the AHU from outside the collector. The study is conducted during winter season when the heating load is highest. - COLLAPSE
    June 2021
  • Article

    Design and Analysis of Yaw Command Tracking Control Algorithm for Wind Turbine for Wind Farm Control Application

    풍력단지제어 적용을 위한 풍력터빈의 요 지령 추종제어 알고리즘 설계 및 해석

    Jeon Taesu ・ Kim Dongmyeong ・ Paek Insu

    전태수, 김동명, 백인수

    This paper proposes the design and analysis of a yaw command tracking control algorithm for wind turbines in wind farm control applications ... + READ MORE
    This paper proposes the design and analysis of a yaw command tracking control algorithm for wind turbines in wind farm control applications. The algorithm was designed for the basic supervisory and power control of a 5 MW research wind turbine proposed by the National Renewable Energy Laboratory (NREL), along with an automatic yaw control designed to verify the results of the analysis using simulations. Additionally, the developed algorithm was used with other control algorithms. The yaw control performance of the proposed tracking algorithm was verified by conducting dynamic simulations using DNV-GL's Bladed program. Furthermore, the operational performance of the algorithm was verified using different simulating situations with different yaw steering commands delivered from a wind farm controller during normal operations, with changes in the wind direction. - COLLAPSE
    June 2021
  • Article

    Comparative Study on the Measurement and Analysis Methods of Heart Rate Variability in Human Body for Occupants’ Thermal Comfort Evaluation by Considering Physiological Response

    재실자 온열쾌적평가에서 인체의 생리적 반응을 고려한 심박변이도 측정 및 분석 방법 비교 연구

    Lim JaeHan

    임재한

    Thermal comfort in humans has been evaluated using predicted mean vote (PMV) based on factors such as clothing and activity levels of ... + READ MORE
    Thermal comfort in humans has been evaluated using predicted mean vote (PMV) based on factors such as clothing and activity levels of an individual to address their satisfaction with the thermal environment. However, PMV does not consider the physiological and psychological factors associated with thermal comfort. A person may feel dissatisfied in an environment that is thermally comfortable for others; this can be calculated by applying heart rate variability (HRV) to the comfort index by measuring the ECG data of the body. Currently, various types of wearable IoT sensors are available for measuring HRV characteristics. In this study, we analyzed the HRV parameters in the human body to evaluate the thermal comfort of the occupant. A data measurement and analysis method using different HRV sensors was developed to determine the feasibility of HRV as a physiological response to the thermal comfort model of the occupant. The characteristic changes in the measured HRV values were analyzed in standard indoor and outdoor environmental conditions. - COLLAPSE
    June 2021
  • Article

    Development of an Empirical Model for Photosynthetically Active Radiation using Global Horizontal Irradiance in Korea

    한반도에서의 전천일사량을 이용한 광합성유효복사량 추정 모델 개발 및 검증

    Choi Kyung Bae ・ Lee Yun Gon ・ Kim Chang Ki

    최경배, 이윤곤, 김창기

    Photosynthetically active radiation (PAR; wavelength 400 ~ 700 nm) is the spectral range of solar radiation used by plants for photosynthesis. PAR data ... + READ MORE
    Photosynthetically active radiation (PAR; wavelength 400 ~ 700 nm) is the spectral range of solar radiation used by plants for photosynthesis. PAR data are used in various fields of research, such as that focusing on surface vegetation growth, the light energy–chemical energy conversion process, and the terrestrial carbon cycle. In this study, we analyze the variability between Global Horizontal Irradiance (GHI) and PAR according to the solar zenith angle, the clearness index, using GHI and PAR observations from 2016 to 2020 at Anmyeondo Flux Tower of Korea Forest Research Institute (KFRI). We confirm that the PAR decreases and the variability of the ratio of PAR to GHI increases as the atmospheric optical path increases. We also confirmed that the PAR increased and the ratio of PAR and GHI decreased as the clearness index increased. Using the results of these relationships and prior studies, we develop and evaluate empirical models that estimate PAR from GHI. The R2 representing the estimation accuracy of the model was 0.988 to 0.996, indicating very high accuracy. With these results, the observation data from the KFRI’s Wando, Pyeongchang, and Samcheok Flux Towers during the same period showed that R2 was very high at 0.977 ~ 0.988, confirming its transferability in other regions. Despite the high R2, the Mean Bias Error (MBE) for each site was shown to be different. To solve this problem, a model with relative humidity and temperature was developed to apply regional conditions for each site, and showed similar R2 to prior models with less MBE. It is expected that the results of this study will be used as policy references such as attracting solar power complexes by drawing up a seasonal map of the Korean peninsula of PAR with solar radiation data observed at the Korea Meteorological Administration's Automated Synoptic Observing System (ASOS). - COLLAPSE
    June 2021
  • Article

    Assessing the Applicability of WRF Terrain Correction and Slope/Shading Effects for Complex Terrain in Gangwon-do

    강원도 복잡지형에 대한 WRF 지형 보정 및 그림자/경사 효과의 수치모의 적용성 평가

    Jo Yong Han ・ Lee Yun Gon ・ Kim Chang Ki

    조용한, 이윤곤, 김창기

    Understanding mountain weather is essential to the prevention and coping with forest disasters such as the wildfires and landslides that have occurred ... + READ MORE
    Understanding mountain weather is essential to the prevention and coping with forest disasters such as the wildfires and landslides that have occurred on the Korean peninsula, a land with large forest areas and complex terrain conditions. However, it is very difficult to accurately simulate irregular and local meteorological phenomena caused by complex terrain using numerical weather models. In the Weather Research and Forecasting (WRF) model, which is a mesoscale model that is widely used for the numerical simulation of meteorological phenomena, parameterization reflecting topographic characteristics (subgrid-scale orography parameterization and slope/shading parameterization) have been developed, but research and application on the Korean peninsula are insufficient. In this study, WRF simulations were performed for the entire period of April, including the wildfire period (from April 4 to 6, 2019) in Goseong, Gangneung, and Inje in Gangwon-do, and the applicability of two parameterizations was evaluated. The difference of meteorological elements (2 m temperature, 2 m relative humidity, 10 m wind speed, and accumulated precipitation) was analyzed according to the parameterization. The results of the 1-km high spatial resolution numerical simulation were compared with the observation data of 122 ground weather stations. The results of the subgrid-scale orography parameterization showed that the forecasting performance of 10m wind speed was greatly improved compared to the control experiment. The overestimated surface wind speed has decreased, reducing the RMSE by 53.0% and the bias by 56.7%. The slope/shading parameterization did not show much difference in values compared to the control experiment, but more realistically simulated the variability of the surface heat flow according to changes in solar altitude. The results of this study indicate that the application of subgrid-scale orography parameterization and slope/shading parameterization can be sufficiently considered in numerical forecasting of the complex terrain of the Korean peninsula, and we suggest that it can improve the forecasting performance of mountain micrometeorology. - COLLAPSE
    June 2021
  • Article

    Adaptive Thermal Comfort of Planned Low-income Housing of a Developing Country: Case of Kigali, Rwanda
    Amina Irakoze・Lee Young-A・Kim Kee Han
    Global warming is expected to raise the average temperature of the tropical region by up to 3–4°C in the next ... + READ MORE
    Global warming is expected to raise the average temperature of the tropical region by up to 3–4°C in the next 70 years. Due to the vulnerable living conditions that are predominant in most developing countries in the region, this will dramatically affect the indoor thermal performance of exclusively, naturally ventilated buildings that form the majority of residential buildings in less-industrialized nations. In addition, the lack of knowledge about the built environment and thermal comfort design guidelines may significantly affect locals’ health and well-being, especially among low-income groups. This study evaluates the thermal performance of low- income housing that were constructed as a governmentsponsored project for urban revitalization in Kigali, Rwanda. Dynamic thermal simulations are carried out through EnergyPlus software using the DesignBuilder program as user interface. Annual discomfort hours and discomfort degree-days are calculated using the ASHRAE 55 adaptive comfort model. The results indicate poor thermal environmental conditions in this planned low-income housing structure. Indoor operative temperature is outside the adaptive comfort range for about 70% of time annually with 955.3 discomfort degree-days. The roof was found to be the key element causing indoor temperature to exceed the upper comfort temperature threshold, while wall material mostly influenced indoor temperature below the lower comfort temperature limit. - COLLAPSE
    June 2021
  • Article

    A Thermal Performance Reliability Study on A Solar Air Collector depending on Ambient Temperature Variation

    외기온도 변화에 대한 공기식 태양열 집열기의 열 성능 신뢰성 검토 연구

    Kim Yu Jin ・ Wang Eun Seok ・ Lee Beom Joon ・ Shin Hyung Ki ・ Lee Euy Joon・Kang Eun Chul

    김유진, 왕은석, 이범준, 신형기, 이의준, 강은철

    Solar air collector is a technology that uses the solar radiation heat energy as a heat source for the ventilation and heating ... + READ MORE
    Solar air collector is a technology that uses the solar radiation heat energy as a heat source for the ventilation and heating of buildings to reduce energy consumption. According to ISO 9806 solar air collector thermal performance evaluation, an indoor performance evaluation method uses a solar radiation simulator in indoor chambers, and an outdoor performance evaluation method uses natural solar radiation in outdoors. The thermal performance evaluation has to ensure the reliability of the thermal performance of the collector using the outdoor performance evaluation method that is affected by the changes in the seasonal outside air temperature. This study compared and analyzed the thermal performance of the glazed solar air collector depending on ambient temperature variations in February, March, and April. The average outside air temperature was –0.5°C in February, 13.4°C in March, and 21.1°C in April. The experiment indicated that the solar air collector thermal performance was 68.1% in February, 68.5% in March, and 63.8% in April and the temperature difference between the inlet and outlet with 1000 W/m2 condition was 29.2°C in February, 27.5°C in March, and 29.0°C in April. These results indicated that seasonal ambient temperature variations had a small effect on the solar air collector thermal performance evaluation. Therefore, the result of the outdoor solar air collector thermal performance evaluation was reliable irrespective of the seasonal ambient temperature changes. - COLLAPSE
    June 2021
  • Article

    Optimistic Analysis of Renewable Energy System in Office Building with HOMER

    HOMER를 이용한 오피스건물의 신재생에너지 최적설계에 대한 고찰

    Lee Byoungdoo

    이병두

    The purpose of this study was to conduct optimal renewable energy analysis of the freezer and boiler application of a typical office ... + READ MORE
    The purpose of this study was to conduct optimal renewable energy analysis of the freezer and boiler application of a typical office building using a Homer (Hybrid Optimization Model for Electric Renewables) program developed by the NREL (National Renewable Energy Laboratory) program. The Stand Alone Model and Grid-Connected MODEL were use to derive the optimum combination of NPC (Total Net Present Cost). The results indicated that the optimum value for the Stand Alone Model is 30 kW PV, 50 KW FC, 30 KW Battery, and the GRID-Connected Model was derived to be optimal to use only GRID. Since there is no renewable energy that has not yet reached Grid Parity, this was considered a predictable result, which further analyzed the optimal combination according to the change in electricity prices and gas prices. The result was optimal (GRID + PV combination) when the current electric dermal is about 2.5 times (gas prices). In conclusion, when the new renewable energy is applied, the PV was more economical than other renewable energy sources, and even if the gas struggle (if the electricity price of $1.2/kWh) is constantly rising, gas prices were not a major factor in the selection of energy combinations. - COLLAPSE
    June 2021
  • Article

    The Analysis of Ventilation Rates and Heat Loss and Gain in Relation to Occupants’ Window Opening Behavior

    거주자의 창문개방행태에 따른 자연환기량과 열손실 및 열획득 분석

    Yoo Jihyun ・ Cho Ga Young ・ Lee Seungrim

    유지현, 조가영, 이승림

    The world’s major advanced countries and the Republic of Korea are reinforcing efforts to realize Zero Energy Building (ZEB) by presenting ... + READ MORE
    The world’s major advanced countries and the Republic of Korea are reinforcing efforts to realize Zero Energy Building (ZEB) by presenting the Green New Deal as a low-carbon leading strategy. In order to realize ZEB, efforts are being made to ensure that the windows and shells of buildings are insulated and air-tight, but no effort has been made regarding the indoor environment. For this reason, the Ministry of Environment continues to strengthen the recommended indoor air quality standards, but most occupants of residential buildings open their windows to improve indoor air quality. However, natural ventilation through the opening of windows may make indoor environments uncomfortable and increase energy consumption through heat loss and heat gain in extreme cold and hot conditions. Therefore, in this study analyzed window-opening behavior, which can increase indoor air quality and affect energy consumption; the amount of natural ventilation was analyzed using the carbon dioxide decay method. Based on the analyzed amount of natural ventilation, heat loss and heat gain were analyzed and compared with energy consumption. - COLLAPSE
    June 2021
  • Article

    Development of AI Algorithm for Power Load Prediction of Refrigeration Compressors for Fish Storage Warehouses

    수산물 보관 창고용 냉동 압축기의 전력부하 예측 AI알고리즘 개발

    Yoo IL-Jun ・ Cha In-Su ・ Kang Yoo-Sik

    유일준, 차인수, 강유식

    In this study, we use the monitoring information of the 214.5RT ammonia screw refrigeration system to show that it is possible ... + READ MORE
    In this study, we use the monitoring information of the 214.5RT ammonia screw refrigeration system to show that it is possible to analyze operation patterns based power load usage, predict power usage, and save energy. We further propose an algorithm to this end. Accidents occur frequently, such as the leaking of ammonia in a recently dilapidated freezer warehouse, and management is an important point of focus because most of the power load in freezer warehouses is drawn by refrigerators. It is important to save energy and predict accidents by using the temperature information of the Meteorological Agency and taking into consideration the pressure and temperature of the refrigerator. In particular, the pressure of the refrigerator changes rapidly according to seasonal changes, and this information could be used to reduce accidents. In addition, as interest in energy saving is increasing worldwide and the reduction of carbon dioxide emissions comes into focus, research on energy saving is being conducted in various fields. In this paper, a prediction algorithm is implemented by analyzing data from the past two years among the monitoring information of a large-scale animal center refrigeration system in Incheon area using deep learning, a type of AI algorithm that has recently attracted attention, as a prediction technique. Among the deep-learning models, an algorithm is designed using RNN (Recurrent Neural Network) and LSTM (Long Short-Term Memory). The RNN and LSTM models have strengths in continuous data pattern analysis. Through this model, data are predicted and performance evaluations are conducted by comparing the power load of refrigerators that have been actually consumed recently, considering the current limiting situation and the direction to move forward. - COLLAPSE
    June 2021
  • Article

    Analysis of Energy Consumption Structure through Detailed Analysis of Energy Source Usage Pattern in Education Facilities

    교육시설 에너지원 이용형태 상세분석을 통한 에너지소비구조 분석

    Kim Da-Sol ・ Choi Jung-Jin ・ Kim Kyu-Jin ・ Jeon Hyun-Woo

    박병용, 조진균, 박두용, 오병철

    The environmental control systems used in educational facilities are diverse and obsolete. To provide safety for students and a pleasant learning environment ... + READ MORE
    The environmental control systems used in educational facilities are diverse and obsolete. To provide safety for students and a pleasant learning environment, various systems are installed in learning spaces. In this study, on-site statistical surveys and energy consumption analyses were conducted in ten educational facilities in South Korea. Through awareness surveys of the persons in charge of education facilities, the energy conservation requirements were investigated. The system configuration was generalized according to the energy source, and through this, it was possible to determine the type of system used. - COLLAPSE
    June 2021
  • Article

    Building Integrated Photovoltaic (BIPV) Demonstration and Power Generation Analysis for The School Building

    학교 건물일체형 태양광 제품 실증 및 발전량 분석

    Park Beungyong ・ Cho Jinkyun ・ Park Dooyong ・ Oh Byoungchull

    김다솔, 최정진, 김규진, 전현우

    This study highlights the advantages of colored building integrated photovoltaics (BIPV) systems that can generate power and renovate obsolete public-school buildings. Multicolored ... + READ MORE
    This study highlights the advantages of colored building integrated photovoltaics (BIPV) systems that can generate power and renovate obsolete public-school buildings. Multicolored BIPV systems were installed in two school buildings and monitored for a specific period to verify their power generation, and power generation data were analyzed together with the solar radiation data from that location. The results from this study can be used to contribute to the widespread adoption of BIPV systems in school buildings in the future. - COLLAPSE
    June 2021