• 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.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제12B권1호
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• pp.24-30
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• 2002

The developments of the solar and the wind power energy are necessary since the future alternative, energies that have no pollution and no limitation are restricted. Currently power generation system of MW scale has been developed, but it still has a flew faults with the weather condition. In order to solve these existing problem combined generation system of photovoltaic(400W) and wind power generation system(400W) was suggested. It combines wind power and solar energy to have the supporting effect from each other. However, since even combined generation system cannot always generate stable output with ever-changing weather condition, power storage apparatus that uses elastic energy of spiral spring to combined generation system was also added far the present study. In an experiment, when output of combined generation system gets lower than 12V(charging voltage), power was continuously supplied to load through the inverter by charging energy obtained from generating rotary energy of spiral spring operates in small scale generator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술대회 논문집 전문대학교육위원
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• pp.171-173
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• 2003

Digital environment that is represented to internet is displacing business way of industry and business achievement way with the fast speed being giving great change on life whole, improve existence business process utilizing internet and Web connection technology, information superhighway to tradition industrialist manufacture and e-transformation's propulsion that wish to maximize productivity and administration efficiency is spread vigorously. In this paper, we wish to accomplish generation equipment's heighten stability and believability through remote monitoring and control of PV system. This paper describes the design of the monitoring system for sensing the monitoring data and indirect controlling of the PV system. Most of the conventional monitoring system depend on the special hardware and software. Basic design goal of monitoring system is to provide the convenience for the user and the portability for the system. In order for the system to fulfill its requirements, it was designed using Labview GUI facility based on the Windows 2000 environment of IBM PC compatible and Add-on card based on the TCP/IP protocol. Advantage of the monitoring system are a personnel expenses curtailment effect, free of the place restriction and unmanned system of the generation plants, etc.

• 전자공학회논문지S
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• 제35S권8호
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• pp.120-129
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• 1998

본 논문은 PWM(Pulse width Modulation)전압형 인버어터를 사용하여 전원차단 경우나 전압변동 및 부하변동에 의한 출력전류 변화에도 일정한 출력전압을 유지하는 무정전 전원장치에 대해 논하였다. 본 시스템은 전압형 인버어터를 교류전원과 동기시켜 운전하고 정상상태에서는 전원으로부터 운전하고 정상상태에서는 전원으로부터 직류측에 연결된 축전지를 태양전지를 이용한 광기전력효과와 함께 일정전압을 충전하며, 전원의 차단, 전원의 전압변동 및 부하전류의 변화에도 일정한 전압을 유지하도록 하였다. 출력은 PWM방식에 의하여 양호한 파형이 되도록 하고 전원차단과 부하의 상태의 변화 및 전원 전압 변동에도 일정한 전압으로 출력됨을 실험을 통하여 확인할 수 있었다.

• 한국태양에너지학회 논문집
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• 제32권3호
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• pp.129-137
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• 2012

This thesis introduced an azimuth tracking prismatic daylighting system. The system improved several issues of the previous passive prismatic daylighting system: low efficiency at sunrise and sunset, glare effect and polarized. The system was developed to track the movement of sun with azimuth tracking device, and it has its own power from the attached solar cells. We compared the with previous passive one in terms with system efficiency and daylighting factors(DF).

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.427-432
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• 2012

This paper proposes efficient operation method of PV system consisted of multi-central which is suitable for large scale system. The multi-central system used switch at a DC-link and applied proposed algorithm can improve the efficiency and the reliability on the existing system. This algorithm, with advantage of Multi-Central system can minimize the effect of different characteristic of each PV array due to a shadow or damaged PV cell. Each system is analysed and maximum power point tracking control, DC-link voltage control and output current control is used commonly. The validity is verified after comparing of the existing system and proposed system by simulation.

• 한국광학회지
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• 제12권1호
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• pp.48-54
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• 2001

광굴절 광기전력 특성을 갖는 Fe를 도핑한 LiNbO$_3$결정에서의 어두운 공간 솔리톤의 발생과 이의 광도파로 역할에 대해 연구하였다. 파장이 488nm인 cw $Ar^{+}$ 레이저를 이용하여 입사빔의 세기가 10mW/$cm^2$ 이하에서도 어두운 공간솔리톤이 발생됨을 관측하였다. 빔의 세기 변화 방향이 광축에 수직인 경우에는 자기확산 효과를 관측할 수 없었으나 광축에 평행한 경우에는 이 효과를 관측할 수 있었다. 이를 통해 매질에서의 굴절률 변화가 빔의 세기 변화 방향과 광축방향이 평행할 때만 일어남을 확인하였다 파장이 633nm인 He-Ne 레이저를 어두운 공간솔리톤에 통과시킴으로써 빔의 집속효과를 관측하였다. 이를 통해 어두운 공간솔리톤의 광도파로 역할을 확인하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.24.1-24.1
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• 2010

In practical operation, the exposed surfaces may get dirty thus degrade the performance of devices. So the combination of self cleaning and antireflection is very desirable for use in outdoor photovoltaic and displaying devices, self cleaning windows and car windshields. For the purpose of self cleaning, the surface needs to be either superhydrophobic or superhydrophilic. However, in practice AR in the visible region and self cleaning are a pair of competitive properties. To satisfy the requirements for superhydrophobic or superhydrophilic surfaces, high surface roughness is required. But it usually cause severely light scattering. Photo-responsive coatings (TiO2, ZnO etc.) can lead to superhydrophilic. However, the refractive indices are high. Thus for porous structure, controlling pore size in the underwavelength scale to reduce the light scattering is very crucial for highly transparent and self cleaning antireflection coating. Herein, we demonstrate a simple method to make high performance broadband antireflection layer on the glass surface, by "carving" the surface by hot alkali solution. Etched glass has superhydrophilic surface. By chemical modification, it turns to superhydrophobic. Enhanced transparency (up to 97%) in a broad wavelength range was obtained by short time etching. Also antifogging effect has been demonstrated, which may offer advantage for devices working at high humidity environment or underwater. Compositional dependence of the properties was observed by comparing three different commercially available glasses.

• 전력전자학회논문지
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• 제17권2호
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• pp.99-106
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• 2012

In this paper, 15[kW] AC regenerative system for battery charging and discharging test is proposed. The regenerative system is able to regenerate surplus energy to the grid in discharging mode, and the inverter of the system can be operated as a converter to compensate scarce energy in charging mode. In case of the conventional DC charging and discharging system, the regenerative energy is consumed by a resistor. However, as the proposed system regenerates the surplus energy to the grid through using DC-AC inverter, the energy saving effect can be achieved. In this paper, 15[kW] battery charging and discharging system is developed, and the validity of the system is verified through simulation and experimental results.

• E2M - 전기 전자와 첨단 소재
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• 제10권9호
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• pp.930-937
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• 1997

Polycrystalline CdTe thin films have been studied for photovoltaic application because of their high absorption coefficient and optimal band energy(1.45 eV) for solar energy conversion. In this study CdTe thin films were deposited on CdS(chemical bath deposition)/ITO(indium tin oxide) substrate by rf-magnetron sputtering under various conditions. Structural optical and electrical properties are investigated with XRD UV-Visible spectrophotometer SEM and solar simulator respectively. The fabricated CdTe/CdS solar cell exhibited open circuit voltage( $V_{oc}$ ) of 610 mV short circuit current density( $J_{sc}$ ) of 17.2 mA/c $m^2$and conversion efficiency of about 5% at optimal sputtering conditions.