• 한국산업융합학회 논문집
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• 제26권6_1호
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• pp.1001-1010
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• 2023

To solve the problem that photovoltaic panels can not harvest electrical energy at a cloudy day and night, a floating solar thermoelectric generator (FSTEG, hereafter) is studied. The FSTEG is consisted of a dome shaped Fresnel lens to condense solar energy, a thermoelectric module connected with a heat sink to keep temperature difference, a floating system simulating a wavy ocean and an electrical circuit for energy storage. The dome shaped Fresnel lens was designed to have 29 prisms and its optical performance was evaluated outdoors under natural sunlight. Four thermoelectric modules were electrically connected and its performance was evaluated. The generated energy w as stored in a Li-ion battery by using a DC-DC step-up converter. For the application of ocean environment, the FSTEG was covered by the dome shaped Fresnel lens and sealed to float in a water-filled reservoir. The harvested energy shows a potential and a method that the FSTEG is suitable for the energy generation in the ocean environment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.79-79
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• 2013

Quantum-structures with nanoparticles have been attractive for various electronic and photonic devices [1,2]. In recent, nonvolatile memories such as nano-floating gate memory (NFGM) and resistance random access memory (ReRAM) have been studied using silicides, metals, and metal oxides nanoparticles [3,4]. In this study, we fabricated nonvolatile memories with silicides (WSi2, Ti2Si, V2Si) and metal-oxide (Cu2O, Fe2O3, ZnO, SnO2, In2O3 and etc.) nanoparticles embedded in polyimide matrix, and photovoltaic device also with SiC nanoparticles. The capacitance-voltageand current-voltage data showed a threshold voltage shift as a function of write/erase voltage, which implies the carrier charging and discharging into the metal-oxide nanoparticles. We have investigated also the electrical properties of ReRAM consisted with the nanoparticles embedded in ZnO, SiO2, polyimide layer on the monolayered graphene. We will discuss what the current bistability of the nanoparticle ReRAM with monolayered graphene, which occurred as a result of fully functional operation of the nonvolatile memory device. A photovoltaic device structure with nanoparticles was fabricated and its optical properties were also studied by photoluminescence and UV-Vis absorption measurements. We will discuss a feasibility of nanoparticles to application of nonvolatile memories and photovoltaic devices.

• Journal of Electrical Engineering and Technology
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• 제7권4호
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• pp.601-605
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• 2012

Insulated Gate Bipolar Transistors(IGBTs) have received wide attention because of their high current conduction and good switching characteristics. To reduce the power loss of IGBT, the onstate voltage drop should be lowered and the switching time should be shortened. However, there is trade-off between the breakdown voltage and the on-state voltage drop. The FLoatingIsland(FLI) structure can lower the on-state voltage drop without reducing breakdown voltage. In this paper, The FLI IGBT shows an on-state voltage drop that is 22.5% lower than the conventional IGBT, even though the breakdown voltages of each IGBT are almost identical.

• 대한토목학회논문집
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• 제34권5호
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• pp.1353-1362
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• 2014

최근 화석연료의 과도한 소비로 인해 다양한 환경문제가 발생하고 있으며, 이에 대한 대안으로 신재생에너지의 중요성과 그에 대한 시설의 수요가 꾸준히 증가하고 있다. 이러한 수요를 만족하기 위하여, 다수의 태양광발전 구조물들이 건설, 계획되고 있다. 그러나 대부분의 태양광발전 시설들은 육지에 시공되고 있기 때문에 토지 이용에 따른 건설비의 증가와 토지 개간에 의한 추가적인 환경문제 등이 발생하고 있다. 이러한 문제점을 해결하기 위하여 최근 국내에서는 FRP를 활용한 수상 부유식 태양광발전 구조물에 대한 연구를 지속적으로 수행하고 있다. FRP는 높은 강도와 내부식성 및 작은 단위중량 등의 장점을 가지고 있기 때문에 최근 토목분야에서 각광받고 있으며, 이러한 재료적 특성은 자중에 따라 부력체의 크기가 결정되는 수상 구조물에 특히 유용하다. 이 연구에서는 수상 부유식 태양광발전 구조물과 구조물을 구성하는 SMC FRP 수직재의 구조적 성능을 평가하기 위한 해석적, 실험적 연구를 수행하였다. 수상 부유식 태양광발전 구조물은 유한요소해석을 통해 정적거동을 평가하고, 실험을 통해 동적거동을 평가하였다. 또한 SMC FRP 수직재는 유한요소해석을 통해 구조안전성 및 좌굴안정성을 평가하였으며, 실험을 통해 압축 및 인발 하중에 대한 구조적 거동 특성을 검토하였다. 검토 결과 펄트루젼 FRP (pultruded FRP)와 SMC (Sheet Modoling Compound) FRP로 구성된 구조시스템은 외부하중에 대한 안전성을 확보하고 있음을 확인하였다.

• 복합신소재구조학회 논문집
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• 제5권1호
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• pp.1-8
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• 2014

Pultruded glass fiber reinforced polymeric plastic (PFRP) and FRP member manufactured by sheet molding compound (SMC) have superior mechanical and physical properties compared with those of conventional structural materials. Since FRP has an excellent corrosion-resistance and high specific strength and stiffness, the FRP material may be highly appreciated for the development of floating-type photovoltaic (PV) power generation system. In this paper, advanced floating PV generation system made of PFRP and SMC is designed. In the design, it includes tracking solar altitude by tilting photovoltaic arrays and tracking solar azimuth by spinning structures. Moreover, the results of the finite element analysis (FEA) are presented to confirm stability of entire structure under the external loads. Additionally, installation procedure and mooring systems in the Hap-Cheon Dam are discussed and the measurement of strain under the actual circumstances is conducted for assuring stability of actually installed structures. Finally, by comparison with allowable stress, appropriate safety of structure is confirmed to operate the system.

• 한국기계가공학회지
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• 제18권11호
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• pp.9-17
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• 2019

Interest in renewable energy is rapidly growing around the world. One of the most popular renewable energy sources is solar power, and photovoltaic (PV) systems are the most representative route for generating solar energy. However, with the growing adoption of solar power systems, the demand for land on which to install these systems has increased, which has caused environmental degradation. Recently, floating PV systems have been designed to utilize idle water surface areas of dams, rivers, and oceans. Because floating PV systems will be exposed to harsh environmental stresses, the safety of such systems should be secured before installation. In this study, the structural robustness of a floating PV system was analyzed by conducting numerical simulation to investigate whether the system can withstand harsh environmental stresses, such as wind and wave loads. Additionally, conventional wind and wave load predictions based on the design method and the simulation results were compared. The comparison revealed that the design method overestimated wind and wave loads. The total drag of the PV system was significantly overestimated by the conventional design criteria, which would increase the cost of the mooring system. The simulation offers additional advantages in terms of identifying the robustness of the floating PV system because it considers real-world environmental factors.

• 한국물환경학회지
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• 제37권6호
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• pp.493-500
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• 2021

Floating solar photovoltaic (hereinafter PV) power generation is emerging as a proper alternative to overcome various environmental limitations of existing offshore PV generation. However, more government-led policy design and technical and institutional development are still required. Based on the policy agenda setting theory and technological innovation theory, this study contains the research questions concerning the co-evolution of technology and the floating solar PV policy. This study primarily evaluates the technological and institutional development level of floating solar PV policy through a survey of domestic floating solar PV experts. Secondly, we also analyze the kind of policy agenda that should be set a priori. Analyzing the priorities to be considered, the first environmental enhancement needs to be considered from both the technical and institutional aspects. The second candidate task for the policy agenda is residents' conflict and improvement of regulations. Both candidate tasks need to be actively considered in the policy agenda from the institutional point of view. The third is publicity, profit sharing, follow-up monitoring, and cost. Among them, public relations and profit sharing are tasks that need to be considered in the policy agenda from the institutional point of view. On the other hand, the cost of follow-up monitoring should be considered as a policy agenda in terms of technology, system, and common aspects. Finally, there are technical standards. Likewise, technical standards need to be considered in the policy agenda in terms of both technical and institutional commonality.

• 조명전기설비학회논문지
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• 제28권12호
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• pp.38-44
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• 2014

The photovoltaic power system is performing power generation by being installed in outdoors. Therefore it has the characteristics affected by environmental factors. In particular, if the solar power generation facility connected to the grid, the power can be generated continuously in a state of being secured operating voltage of the inverter and solar irradiation. In that case, if an abnormal situation such as flooding or heavy rains has occur, the possibility of electric shock or damage of facilities due to current leakage or a floating matters is present. In this paper, we performed electrical safety assessment about the connection part, junction box and cable of the solar module when the solar power system was flooded. we also assessed whether or not the leakage current is occurred in case of the cable was damaged. As a result, in case of the leakage current is large, we can be known that it is the risk of electric shock as well as cause of inverter damage.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.686-694
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• 2014

A power semiconductor device, usually used as a switch or rectifier, is very significant in the modern power industry. The power semiconductor, in terms of its physical properties, requires a high breakdown voltage to turn off, a low on-state resistance to reduce static loss, and a fast switching speed to reduce dynamic loss. Among those parameters, the breakdown voltage and on-state resistance rely on the doping concentration of the drift region in the power semiconductor, this effect can be more important for a higher voltage device. Although the low doping concentration in the drift region increases the breakdown voltage, the on-state resistance that is increased along with it makes the static loss characteristic deteriorate. On the other hand, although the high doping concentration in the drift region reduces on-state resistance, the breakdown voltage is decreased, which limits the scope of its applications. This addresses the fact that breakdown voltage and on-state resistance are in a trade-off relationship with a parameter of the doping concentration in the drift region. Such a trade-off relationship is a hindrance to the development of power semiconductor devices that have idealistic characteristics. In this study, a novel structure is proposed for the Insulated Gate Bipolar Transistor (IGBT) device that uses conductivity modulation, which makes it possible to increase the breakdown voltage without changing the on-state resistance through use of a P-floating layer. More specifically in the proposed IGBT structure, a P-floating layer was inserted into the drift region, which results in an alleviation of the trade-off relationship between the on-state resistance and the breakdown voltage. The increase of breakdown voltage in the proposed IGBT structure has been analyzed both theoretically and through simulations, and it is verified through measurement of actual samples.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.57-60
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• 2005

The existing DSP for utility interactive photovoltaic generation system control, generally uses floating point process type. Because it is easy to use for number crunching, However it is too late and too expensive. fixed point process DSP, TMS320F2812, has high control speed and is rather inexpensive. This paper presents more efficient method for MPPT control using TMS320F2812.