• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.662-671
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• 2020

Recently, for the purposes of reducing carbon dioxide(CO₂) emissions in the island area, countermeasures to decrease the operation rate of diesel generator(DG) and to increase one of renewable energy sources(RES) is being studied. In particular, the demonstration and installation of stand-alone micro-grid(MG) system which is composed of DG, RES and energy storage system(ESS) has been implemented in some island areas such as Gapa-do, Gasa-do and Ulleung-do island. However, many power quality(PQ) problems may be occurred due to an intermittent output of RES including photovoltaic(PV) system and wind power(WP) system in a normal operating of constant voltage & constant frequency(CVCF) inverter-based MG system. Therefore, this paper presents a modeling of the 30kW scale MG system using PSCAD/EMTDC, and also implements a 30kW scale CVCF inverter-based MG system as test devices to analyze normal operating characteristics of MG system. From the simulation and test results, it is confirmed that the proposed methods are useful and practical tools to improve PQ problems such as under-voltage, over-voltage and unbalanced load in CVCF inverter-based MG system.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2227-2235
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• 2018

Under the current policies and compensation rules in South Korea, Photovoltaic (PV) generation supplier can maximize the profit by combining PV generation with Energy Storage System (ESS). However, the existing operational strategy of ESS is not able to maximize the profit due to the limitation of ESS capacity. In this paper, new ESS scheduling algorithm is introduced by utilizing the System Marginal Price (SMP) and PV generation forecasting to maximize the profits of PV generation supplier. The proposed algorithm determines the charging time of ESS by ranking the charging schedule from low to high SMP when PV generation is more than enough to charge ESS. The discharging time of ESS is determined by ranking the discharging schedule from high to low SMP when ESS energy is not enough to maintain the discharging. To compensate forecasting error, the algorithm is updated every hour to apply the up-to-date information. The simulation is performed to verify the effectiveness of the proposed algorithm by using actual PV generation and ESS information.

• KIEAE Journal
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• v.12 no.1
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• pp.105-112
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• 2012

When a building is planned and designed, the design should be able to minimize the cost during the whole life cycle of the building. This study has begun to analyze LCC about the alternative design which is applicable to renewable energy facility construction. It is reviewed domestic and foreign papers about the trend of LCC technology and it is determined the analytical method to analyze the LCC of renewable energy. Regarding the review of alternatives, it is chosen the three alternatives which are able to designed combing the renewable energy facilities and it is performed the LCC analysis about each alternative. Alternative 1 is Photovoltaic + Solar Thermal + Photovoltaic /Wind Power, Alternative 2 is Geothermal + Photovoltaic, and Alternative 3 is Photovoltaic + Solar Thermal. The LCC analysis is present value method, its analytical period is 40 years and it is applied 3.2% of real discount rate. As a result, it is proved that Alternative 1 and Alternative 3 are not able to collectible the early investment cost during the analytical period and Alternative 2 is analyzed that its pay-back period of early investment cost is about 31 years. As the final outcome of this study on case analysis, it is more advantageous to use the combination of Geothermal and Photovoltaic energy than to use the other combination in LCC aspect.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.889-894
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• 2008

Exhaust system used in toilet and cooking place of high riser public house is roof fan of two basic types : natural roof ventilator and natural/forced roof ventilator. Natural/forced roof ventilator has a motor in the rotary shaft. There are many high riser public house in Korea. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depend on stack effect. This study investigates on stack pressure determined by exterior pressure and the difference pressure control in exhaust stack used in high riser public house. This paper focuses mainly on the effect of the time interval for power supply of motor installed in roof fan with function of natural wind velocity and of exhaust air volume of toilet. It is observed there are higher exhaust efficiency than the existing natural roof ventilator.

• Journal of Radiation Industry
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• v.9 no.4
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• pp.181-185
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• 2015

Today the biosafety evaluation, a common problem of vital importance, is based on internationally proved test-systems, standards and techniques. The paradigm of biosafety includes multidisciplinary approach, a combination of physical, chemical and biological tests to monitor the environmental level of pollutants and needs to be improved by modern approaches. The genetic risk of environmental pollutions has long been studied by many researchers. In this study, used was the known sensitive plant test-system, clones of plant Tradescantia (spiderwort) able to detect gene mutations (frequency of mutational events and formation of micronuclei) in combination with chemical and, in some instances, with radiological measurements. In addition, male gametophyte generation of fruit trees was applied as bioindicators of genotoxicity. The obtained results did not show any significant increase along with wind direction. As for the male gametophyte assay, the fertility of the investigated fruit-trees near to NPP did not significantly differ from that of the control point. The influence of the NPP on the male generative system of the investigated taxa of fruit trees for the investigated year was not revealed. The system described needs to be expanded by species of interest (human) as there is a difficulty to transfer the revealed dose correlations to humans. The development of this idea includes various levels: population (epidemiological studies), individual, cellular, molecular (DNA), etc.

• Journal of Ocean Engineering and Technology
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• v.35 no.3
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• pp.229-237
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• 2021

A numerical hydrodynamic performance analysis of the pitch-type multibody wave energy converter (WEC) is carried out based on both linear potential flow theory and computational fluid dynamics (CFD) in the unidirectional wave condition. In the present study, Salter's duck (rotor) is chosen for the analysis. The basic concept of the WEC rotor, which nods when the pressure-induced motions are in phase, is that it converts the kinetic and potential energies of the wave into rotational mechanical energy with the proper power-take-off system. This energy is converted to useful electric energy. The analysis is carried out using three WEC rotors. A multibody analysis using linear potential flow theory is performed using WAMIT (three-dimensional diffraction/radiation potential analysis program), and a CFD analysis is performed by placing three WEC rotors in a numerical wave tank. In particular, the spacing between the three rotors is set to 0.8, 1, and 1.2 times the rotor width, and the hydrodynamic interaction between adjacent rotors is checked. Finally, it is confirmed that the dynamic performance of the rotors slightly changes, but the difference due to the spacing is not noticeable. In addition, the CFD analysis shows a lateral flow phenomenon that cannot be confirmed by linear potential theory, and it is confirmed that the CFD analysis is necessary for the motion analysis of the rotor.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1306-1308
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• 2002

본 논문에서는 태양광-풍력 복합발전시스템의 구성에 있어서 태양전지 어레이, 풍력발전기 및 축전지의 최적 용량 결정방법에 관하여 연구하였다. 본 연구에서는 서울지역의 일사량 및 풍속 데이터를 사용하여 일사량과 풍속의 확률밀도함수를 구하였고, 또한 태양전지와 풍력발전기의 파라미터를 사용하여 복합발전시스템의 평균출력을 예측하였다. 이 평균출력과 도시지역 주택 수용가의 전형적인 부하패턴을 고려하여 태양광-풍력 복합발전시스템을 구성할 경우 태양전지 어레이, 풍력발전기 및 축전지의 용량을 최적으로 결정하는 방법에 관하여 연구하였다.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.127-128
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• 2013

본 논문은 POSCO ICT가 개발한 2MVA/500kWh급 BESS(Battery Energy Storage System)의 가파도 마이크로그리드 적용사례와 실증결과에 대해 기술하였다. 이를 위해 가파도 마이크로그리드 구성과 BESS 역할을 설명하였고, 적용된 기술을 소개하였다. 또한 시험항목과 의의를 서술하고, 시험결과를 통해 계통망의 전력품질 및 BESS 제어성능을 검증하였다.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.379-381
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• 1996

본 논문에서는 그리드 독립형 태양광 풍력 복합 발전 시스템에 대한 최적의 태양광 어레이 사이즈 및 풍력 발전 시스템을 결정하는 방법을 제안하였다. 연구에 사용되어진 풍력 및 태양광 일사량에 대한 데이터는 제주도 지역에서 1년간 실측되어진 데이터를 기준으로 하였으며, 이러한 실측되어진 데이터는 풍속 및 태양광의 확률 밀도 함수(Probability Density Function)를 결정하는데 사용되어 졌다. 풍속 및 태양광 일사량의 확률 밀도 함수와 태양광 어레이 및 풍력 발전기의 여러 파라미터는 복합 발전 시스템의 평균 발생 전력을 계산하는데 사용하였고, 도서지역에서 1년간 계측되어진 부하의 변동에 대하여 최적의 태양광 어레이, 풍력 발전 용량을 선정 하기 위하여 최적 자승의 법칙이 사용되었다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.372-373
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• 2011

대규모 풍력발전 단지의 전력 계통에서 발생되는 전력손실의 종류를 분석하고 손실 저감 대책을 경제성 평가를 통해서 검토하였다. 검토결과 풍력발전 단지의 경우 부지면적이 넓어 배전선로에 의한 손실이 크고, 풍력발전설비의 설비 이용율(Capacity Factor)과 전력판매단가가 타 발전설비에 비해 상대적으로 높기 때문에 발전소내의 가공전선의 크기를 크게 선정하는 경우 투자비 대비 전력 손실 감소로 인한 발전량 증가로 얻는 경제적 이득이 더 크므로 경제적인 손실 저감 대책인 것으로 검토되었다.