• Research Article

    Optimal PV Design for Educational Facilities Considering Renewable Energy Installation Obligation and Load Matching

    신재생에너지 설치 의무화 제도와 부하 매칭을 고려한 교육시설 최적 PV 설계

    Chang-Hwan Kim, Eui-Jong Kim

    김창환, 김의종

    The purpose of this study is to determine the optimal tilt angle for fixed solar modules that can meet the hourly electricity … + READ MORE
    The purpose of this study is to determine the optimal tilt angle for fixed solar modules that can meet the hourly electricity demand of a school facility. Simulations were conducted to reflect the load characteristics of a middle school located in Seoul to calculate the net power consumption for various tilt angles of the solar modules. The results revealed that the optimal tilt angle was 16°, resulting in an approximately 3.5% increase in annual power savings compared with existing solar module installation guidelines. Therefore, it is recommended that the tilt angle of the solar modules within a range of lower tilt angles, including 16°, is ideal. Because the optimal tilt angle of solar modules may vary depending on the target building, there is a need for solar installation guidelines that propose tilt-angle designs that consider building load characteristics. - COLLAPSE
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    30 June 2024

  • Research Article

    Comparative Analysis of FFT and DWT Techniques Required for UL 1699B-based Photovoltaic DC Series Arc Detection

    UL 1699B 기반 태양광 DC 직렬 아크 검출에 필요한 FFT와 DWT 기법 비교 분석 연구

    Juntae Jeon, Taejun Park, Sunwoo Lim, Jinho Do, Hyojun Lee, Beomjun Kim, Youngkwon Lee, Seungho Song, Juyeop Choi

    전준태, 박태준, 임선우, 도진호, 이효준, 김범준, 이영권, 송승호, 최주엽

    Considering the dangers of DC serial arcs in PV systems and the time when arcs are caused by electrical fire, we aimed … + READ MORE
    Considering the dangers of DC serial arcs in PV systems and the time when arcs are caused by electrical fire, we aimed to quickly detect DC serial arcs within 0.5 s. To quickly analyze and identify the frequency characteristics of arcs, fast Fourier transform (FFT) and discrete wavelet transform (DWT), which have been the most widely used frequency analysis methods in recent years, were compared and analyzed to implement an algorithm for detecting the most accurate and efficient DC arc. In this study, an experiment was conducted based on the UL 1699B arc test conditions. At this time, the arc energy does not exceed 750 J, and the arc must be detected within 2.5 s. In the overall process, components other than the arc were removed by applying a band pass filter to detect a specific frequency component of the arc. ADC was performed to convert the current value into a digital signal, and signal processing was performed using FFT and DWT using the filtered signal. Finally, after calculating the energy, which is a component of the frequency for each specific period, the threshold of each energy value was set to determine whether the arc exceeds a specific threshold. - COLLAPSE
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    30 June 2024

  • Research Article

    Building Energy Efficiency through the Application of Digital Twin-based BEMS

    디지털 트윈 기반의 BEMS 적용을 통한 건물에너지 효율화 방법

    Jaemin Hwang, Jiwon Kim, Sungmin Yoon

    황재민, 김지원, 윤성민

    Building energy management systems (BEMS) are widely used to improve building energy efficiency. However, beyond simple monitoring and management, there are still … + READ MORE
    Building energy management systems (BEMS) are widely used to improve building energy efficiency. However, beyond simple monitoring and management, there are still limitations to implementing specific methods for energy savings and efficiency improvements during the operational phase. Simultaneously, the concept of a digital twin (DT) has been actively researched as a concept for the interaction of data and operational information between real buildings and virtual models. By integrating the DT concept into the BEMS, smooth communication between real buildings and virtual models is possible. A virtual model is defined as a mathematical model that describes physical behavior during the operational phases of a real building. This model can provide building energy efficiency methods based on real building data and the physical behavior of the building. Therefore, this study proposes a DT-based BEMS (DT-BEMS). A DT-BEMS consists of predicted mean vote (PMV) virtual sensors, energy sub-metering virtual sensors, and Holistic Operational Signature (HOS) analysis methods. Utilizing data from the BEMS, PMV virtual sensors obtain the PMV in real residential areas. After applying the virtual sensors, the HOS categorizes the operational states and offers energy optimization information. In this study, a DT-BEMS environment was developed for an office building. Thus, an organic process was realized in which real building data were transmitted through virtual models to provide energy efficiency information back to the target building. - COLLAPSE
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    30 June 2024

  • Research Article

    Effectiveness Analysis of Simultaneous Cooling and Heating System with Solar Energy in Summer

    여름철 태양에너지를 적용한 동시냉난방 시스템의 효용성 분석

    Seokhyun Lee, Yujin Lee, Dae-Uk Shin

    이석현, 이유진, 신대욱

    Simultaneous heating and cooling systems (SHC) can eliminate both the heating and cooling loads in a single run of the heat pump. … + READ MORE
    Simultaneous heating and cooling systems (SHC) can eliminate both the heating and cooling loads in a single run of the heat pump. This system is effective for buildings that require simultaneous heating and cooling. However, the use of a secondary heat source is inevitable because cooling and heating are not always equal. In a building, assuming that the cooling load is higher than the heating load, the cooling load that cannot be eliminated by a simultaneous cooling and heating system, and it must be covered by auxiliary cooling equipment. In Korean summers, the cooling load in a building is higher than the heating load. In such an environment, the SHC uses less heating energy, resulting in an increased operation of the auxiliary equipment for cooling. To decrease the use of auxiliary equipment and increase the use of SHC, it is necessary to reduce the heating energy of the SHC. For this purpose, an absorption chiller was used to convert the unused heating energy into cooling energy. In addition, to decrease the energy use of the whole system, photovoltaic (PV) panels that can use solar photovoltaic energy were installed to generate a part of the power used in the system, and solar heat energy was applied for the regeneration of the absorption chiller. In this study, the energy consumptions of a conventional SHC and an SHC using solar energy were analyzed by comparing the methods used for a building in which the cooling load is much higher than the heating load during summers. - COLLAPSE
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    30 June 2024

  • Research Article

    Metal-Oxide Based Transparent Heater with Interdigitated Electrodes

    교차 전극을 이용한 금속 산화물 기반의 투명 히터

    Junghyun Lee, Chanhyuk Choi, Kumail Muhammad, Bhatnagar Priyanka, Patel Malkeshkumar, Joondong Kim

    이정현, 최찬혁, 무하마드쿠마일, 프리양카바트나가, 말케시쿠마파테르, 김준동

    This study aimed to compare and analyze various transparent heaters to ascertain their potential applications in smart windows. Transparent heaters have promising … + READ MORE
    This study aimed to compare and analyze various transparent heaters to ascertain their potential applications in smart windows. Transparent heaters have promising applications in fields where visibility is essential. Their applications in buildings and vehicles offer significant advantages. A major benefit is their ability to operate with minimal energy consumption, thereby contributing to energy saving for heating. Additionally, their transparency provides superior visual aesthetics, and their high infrared reflectivity is effective in reducing heat transfer through glasses by loss, helping maintain the quality of indoor temperatures and environments. The transparent heater functions according to the Joule heating principle, in which reducing the resistance and enhancing the current flow under a specific voltage leads to increased heat production. For active transparent heaters, the optical and electrical profiles of a single ITO film and ITO/Ag/ITO (oxide/metal/oxide, OMO) structures were investigated. The OMO structure provides a substantially low resistance (2.2 Ω/□) and high optical transmittance (76%). An interdigitated electrode was designed to provide multiple current paths for improving current flow. The suitability of the structures was assessed by comparing the results of each characteristic. OMO-structured transparent heaters exhibit excellent optical and electrical properties, making them suitable for application as films on glass in the structural, surface, and automotive industries. - COLLAPSE
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    30 June 2024
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