• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.119.2-119.2
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• 2011

Dye-sensitized solar cells (DSSC) are currently attracting wide spread academic and commercial interest for the conversion of sunlight into electricity because of their easy manufacturing process and high efficiency. The solar energy conversion efficiencies of DSSC are strongly dependent on dye molecules adsorbed on the TiO2 surface which used for photosensitization of sun light, since an excited state of dye could inject an electron into the conduction band of semiconductor. We have developed novel organic dyes which have phenothiazine moieties as an electron donor in their charge-transfer chromophore for application of DSSCs. We had synthesized a series of phenothiazine derivatives which have different wave length absorbing chromophore in the molecule with high molar extinction coefficient. The photovoltaic performance of DSSC composed of organic chromophores with broad wavelength absorption property were measured and evaluated by comparison with that of pristine ruthenium dye.

• 한국태양에너지학회 논문집
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• 제32권2호
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• pp.1-10
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• 2012

A photovoltaic/thermal (PVT)solar system is the solar technology that allows for simultaneous conversion of solar energy into both electricity and heat. This paper compared the performance of PVT system with a conventional PV module and solar collector and analyzed electrical and thermal efficiency of PVT system in terms of solar irradiance and inlet temperature of the working fluid. Based on the experimental data, thermal and electrical efficiencies of he glazed PVT system were57.9% and14.27% under zero reduced temperature condition which were lower by 13.6% than the solar thermal absorber plate and by 0.08% than the PV module respectively. For the unglazed PVT system it had lower thermal efficiency than the solar thermal absorber plate but higher electrical performance than the PV module due to the cooling effect by the working fluid. However, total efficiency of the glazed PVT system was72.2% which was higher than combined efficiencies of the solar collector and PV module. Besides, total efficiency of the PVT system would be much higher if calculated based on unit area.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.60-67
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• 2011

A photovoltaic/thermal(PVT)solar system is the solar technology that allows for simultaneous conversion of solar energy into both electricity and heat. This paper compared the performance of PVT system with a conventional PV module and solar collector and analyzed electrical and thermal efficiency of PVT system in terms of solar irradiance and inlet temperature of the working fluid. Based on the experimental data, thermal and electrical efficiencies of the glazed PVT system were 57.9% and 14.27% under zero reduced temperature condition which were lower by 13.6% than the solar thermal absorber plate and by 0.08% than the PV module respectively. For the unglazed PVT system, it had lower thermal efficiency than the solar thermal absorber plate but higher electrical performance than the PV module due to the cooling effect by the working fluid. However, total efficiency of the glazed PVT system was 72.2% which was higher than combined efficiencies of the solar collector and PV module. Besides, total efficiency of the PVT system would be much higher if calculated based on unit area.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.675-676
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• 2014

Photovoltaic (PV) systems bosed on solar energy offer an environmentally friendly source of electricity. A key feature of such PV sysem is the efficiency of conversion at which the power converter stage can extract the energy from the PV arrays and deliver to the load. The Maximum power point tracking (MPPT) of the PV output for all sunshine conditions allows reduction of the cost installation and maximizes the power output from the PV panel. The proposed algorithm is to control the width of the pulse for battery charging based on the open voltage of the PV panel. As a lab results, the proposed system was implemented functions to adapt to the changes of the PV open voltage, and improved the charging efficiency.

• 접착 및 계면
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• 제23권2호
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• pp.39-43
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• 2022

디스플레이, 태양전지와 같이 전기를 빛으로, 또는 빛을 전기로 변환시켜주는 광전자소자는 효율 향상을 위하여 빛의 거동 제어가 매우 중요하다. 즉, OLED의 경우 내부 빛 제어를 통해 더 많은 빛이 외부로 나갈 수 있도록 유도해 줄 때 발광효율을 향상시킬 수 있으며, 외부 빛 제어를 통해 광흡수층에서의 광경로를 증대시킬 경우 태양전지의 에너지 변환효율을 증가시킬 수 있다. 본 연구에서는 이러한 광거동 제어가 가능한 구조로서 주름구조에 대한 연구를 진행하였으며 응력 해소 시간을 제어하여 구조의 주기와 높이를 독립적으로 제어하고자 하였다. 주기와 높이의 변화가 광거동에 어떠한 영향을 미치는지 살펴보기 위하여 일정한 주기에서 높이 변화 및 유사한 높이에서 주기 변화에 따른 자외선/가시광선 분광분석(UV/Vis spectroscopy)을 실시하였으며 구조의 종횡비가 클수록 직진광의 비율이 낮고 분산광의 비율이 높음을 확인하였다. 이를 통해 광경로 변화 및 광경로 증가를 위하여 큰 종횡비의 주름구조가 요구됨을 확인할 수 있었다.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1864-1873
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• 2018

Energy shifting is an innovative method used to obtain the highest profit from the operation of energy storage systems (ESS) by controlling the charge and discharge schedules according to the electricity prices in a given period. Therefore, in this study, we propose an optimal charge and discharge scheduling method that performs energy shift operations derived from an ESS efficiency model. The efficiency model reflects the construction of power conversion systems (PCSs) and lithium battery systems (LBSs) according to the rated discharge time of a MWh-scale ESS. The PCS model was based on measurement data from a real system, whereas for the LBS, we used a circuit model that is appropriate for the MWh scale. In addition, this paper presents the application of a genetic algorithm to obtain the optimal charge and discharge schedules. This development represents a novel evolutionary computation method and aims to find an optimal solution that does not modify the total energy volume for the scheduling process. This optimal charge and discharge scheduling method was verified by various case studies, while the model was used to realize a higher profit than that realized using other scheduling methods.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.85-92
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• 2018

수요관리를 통해 전기요금을 절감할 수 있다. 부하의 수요 관리 방법 중 하나로 ESS를 설치해 수요가 높은 시간대의 부하를 수요가 낮은 시간대로 옮기는 peak shifting을 사용함으로써 최대 부하를 낮추고 전력량 요금을 절감할 수 있다. 전기요금은 계약 용량 당 기본요금과 전력량 요금으로 이루어져있다. 전력량 요금을 최소화하기 위한 최적화 수행시 목적함수는 선형식으로 표현할 수 있으며, 기본 요금 최소화를 위한 목적함수는 이차식으로 표현할 수 있다. 선형식으로 표현된 목적함수에서는 ESS PCS(Power Conversion System)의 충, 방전 효율이 다른 경우를 다룰 수 없기 때문에 본 논문에서 충, 방전 효율이 다른 경우의 영향을 반영하고 혼합정수계획법(MILP, Mixed Integer Linear Programming)을 이용할 수 있는 정식을 제시하였다. 혼합정수계획법을 사용한 정식에서는 사전에 정해진 최대 부하 절감율에 대해 전기요금 최소화를 수행하게 되지만 최대 부하 절감과 전기요금 절감을 동시에 고려하기 위해서는 이차 계획법을 사용하는 것이 유용하다. 본 논문에서는 각 최적화 방법에 대한 장, 단점을 도시철도 변전소에 대한 시뮬레이션 결과를 정량적으로 비교분석하여 ESS 설비계획수립에 적합한 최적화 방법을 선택할 수 있는 근거를 제시하였다.

• 한국항해항만학회지
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• 제38권1호
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• pp.39-44
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• 2014

최근 전 세계적으로 고유가 상황이 지속됨에 따라 신재생에너지원에 대한 연구가 활발히 진행되고 있다. 그중 해양에너지는 그 양이 매우 많고 밀도가 높기 때문에 활용성이 높다. 특히 우리나라의 경우 삼면이 바다로 둘러싸여있기 때문에 해양에너지원이 매우 풍부하다. 본 논문은 해양에너지를 전력으로 변환하는 시스템중 하나인 방파제형 파력발전 시스템에 수평판 설치를 통한 발전 효율 향상에 관하여 서술하였다. 기존의 방파제형 파력발전 상부에 수평판을 설치함으로써 시스템의 전력변환효율을 향상시킬 수 있으나 아직까지 국내에서는 이에 대한 연구가 미흡하다. 본 논문에서는 조파수조 실험을 통하여 수평판이 방파제형 파력발전 시스템에 미치는 영향에 대해 분석하고, 본 시스템에 적합한 수평판 설치에 대해 제안한다.

• 한국환경보건학회지
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• 제39권5호
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• pp.474-481
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• 2013

Objectives: This study was conducted to investigate the application of microbial fuel cells (MFCs) to the wastewater treatment systems employed in the Living Building Challenge. Methods: I reviewed a range of information on decentralized wastewater treatment technologies such as composting toilets, constructed wetlands, recirculating biofilters, membrane bioreactors, and MFCs. Results: The Living Building Challenge is a set of standards to make buildings more eco-friendly using renewable resources and self-treating water systems. Although there are various decentralized wastewater treatment technologies available, MFCs have been considered an attractive future option for a decentralized system as used in the Living Building Challenge. MFCs can directly convert substrate energy to electricity with high conversion efficiency at ambient and even at low temperatures. MFCs do not require energy input for aeration if using open-air cathodes. Moreover, MFCs have the potential for widespread application in locations lacking water and electrical infrastructure Conclusions: This paper demonstrated the feasibility of MFCs as a novel decentralized wastewater treatment system employed in the Living Building Challenge.

• 한국해양공학회지
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• 제29권4호
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• pp.317-321
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• 2015

Many kinds of generation systems have been developed to use ocean energy. Among these, with the use of an oscillating water column (OWC) for power generation is attracting attention. The OWC-type wave power generation system converts wave energy into electricity by operating a generator turbine with the oscillating water level in a column of water. There are two ways to convert wave power into electricity using an OWC. One uses a cross-flow turbine using the water level inside the OWC. The other method uses the flow of air in a Wells turbine, which depends on the water level. An experiment was carried out using a 2-D wave tank in order to minimize the number of empirical tests. The design factors were taken from Koo et al. (2012) and the experimental environment assumed by free surface motion. This paper deals with characteristics of two types of wave energy conversion systems combine with a breakwater. One model uses an air-driven Wells turbine and a cross-flow water turbine. The other type uses a cross-flow water turbine. Wave energy converters with OWCs have mostly been studied using air-driven Wells turbines. The efficiency of the cross-flow turbine was about 15% higher than that of the other model, and the water level of the OWC internal chamber for the cross-flow water turbine and air-driven Wells turbine was less than about 40% lower than the one using only the cross-flow water turbine.