• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.25-30
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• 2011

In this paper, we analyzed the electrical characteristics with Micro-cracks in Photovoltaic module. Micro cracks are increasing the breakage risk over the whole value chine from the wafer to the finished module, because the wafer or cell is exposed to mechanical stress. And The solar cells have to with stand the stress under out door operation in the finished module. Here the mechanical stress is induced by temperature changes and mechanical loads from wind and snow. So, we experimentally analyze the direct impact of micro-cracks on the module power and the consequences after artificial aging. The first step, we made micro-cracks in PV module by mechanical load test according to IEC 61215. Next, PV modules applied the thermal cycling test, because micro-cracks accelerated aging by thermal cycling test, according to IEC61215. Before every test, we checked output and EL image of PV module. As the result of first step, we detected little power loss(0.9%). But after thermal cycling test increased power loss about 3.2%.

• Journal of the Korean Solar Energy Society
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• v.28 no.4
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• pp.62-67
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• 2008

In this study, we analyze the electrical characteristics of amorphous silicon thin film photovoltaic module which are installed about 5 years ago. Four modules from PV system are extracted and measured the maximum power change ratio using solar simulator(Class A). Also, infrared camera is used to get thermal distribution characteristics of system. The external appearance change is compared with initial module by naked eye examination. Through this experiment, 31% maximum output power drop is observed. The detail description is specified as the following paper.

• Journal of the Korean Solar Energy Society
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• v.28 no.1
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• pp.65-74
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• 2008

In this study, dynamic characteristics analysis of AC system is investigated using a cool thermal storage system. A analysing program for cool thermal storage AC system is developed. The performances are studied by several variables and dynamic characteristics. Comparing the result at conventional operation condition with that at the condition using ice storage system, this study showed the effects of the sub cooled degree, superheated degree, efficiency of compressor and evaporating temperature. At the condition using thermal storage system, the thermal storage process was operated during midnight being not needed the cooling of the AC unit through the continuous running of the condenser. The refrigerant was sub-cooled using stored energy after being discharged from the air source condenser during the daytime. The COP was increased owing to the sub-cooling of refrigerant during daytime, thus the power consumption was effectively decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.9-10
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• 2007

In this paper, we investigated the effect of solar cell breakage on maximum output power of PV module. The test result using artificial light source didn't give any change in output power in case of crack near electrical ribbon. Also, there was a reduction in output power in case of increasing of crack area far from electrical ribbon. But, this experiment is under artificial light source test method. So, when such a PV module is outdoor for a long time, there would be problems on electrical output power and durability because of thermal aging phenomenon of solar cell breakage.

• Journal of Hydrogen and New Energy
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• v.17 no.3
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• pp.338-346
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• 2006

In this paper, the test results of medium-size(120 kW class) PV system which was installed in the Taeahn thermal power station of Korea Western Power Co., Ltd., were summarized for developing the practical technology to applicate high voltage grid connection PV system. The 120 kW photovoltaic system which was consisted of 1,300 modules, PCS, and 150 kVA transformer station has been operated since Aug. 05, 2005. For verifying the modeling results of PV system, the operation data was compared with modeling results which was executed commercial PSCAD/EMTD and Psim tools. An equivalent circuit model of a solar cell has been also used for solar array modeling. A series of parameters required for array modeling have been estimated from general specification data of a solar module. A PWM voltage source inverter(VIS) and its current control scheme have been analyzed by using P&O (perturbation and Observation) MPPT algorithms technique.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.653-657
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• 2007

Since the direct normal insolation is a main factor for designing any solar thermal power system, it is necessary to evaluate its characteristics all over the country. We have begun collecting direct normal insolation data since December 1990 at 16 different locations and considerable effort has been made for constructing a standard value from measured data at each station. KIER(Korea Institute of Energy Research's new data will be extensively used by solar thermal concentrating system users or designers as well as by research institutes. From the results, we can conclude that 1) Yearly mean 5.41kWh/$m^2$/day of the direct normal insolation was evaluated for clear day all over 16 areas in Korea. 2) Clear day's direct normal insolation of spring and summer were 5.54kWh/$m^2$/day and 5.86kWh/$m^2$/day, and for fall and winter their values were 5.32kWh/$m^2$/day and 4.92kWh/$m^2$/day respectively. So, spring and summer were higher, and fall and winter were lower than the yearly mean value.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.4
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• pp.159-164
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• 2021

The Improvement of thermal performance using heat treatment of carbon nanotubes coated on the copper heat sink to take the radiation energy from solar ray for the energy harvesting in earth orbit. Using the additive coating of purified CNT for the increase of specific area and development of thermal conductive capacity, the performance of heat transfer is improved about 0.181 K/W while applying the power of 22 W under temperature of 3.98℃. Coating of purified CNT shows increase of area and volume of thermal layer however it led the partial thermal resistance.

• Electrical & Electronic Materials
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• v.10 no.8
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• pp.843-851
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• 1997

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.672-675
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• 2007

Experimental data are presented which describe heat losses of cavity type receiver in wind tunnel. Experiments are conducted at various conditions such as the heater temperature in cavity changes from 300, 400, and 500 oC, wind speed in tunnel from 2 to 8 m/s, and four different tilt angle of 30, 50, 70, 90o. The power consumption including temperature, voltage and current for each experimental conditions are measured and stored in data logger at everyone second interval. The experimental results show that heat losses increase with increasing wind speed and with tilt angle. However, heat losses for the tilt angle of 70 and 90o is almost same at each heater temperature. In addition, the effects of natural convection in combined convection heat losses vary in according to the tilt angle.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.1017-1026
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• 2009

The solar cell system operates by facing the sun-light. Minor cracks, static discharge, and thermal shock that can happen during production/testing phase can lead to degradation in performance during operation, since solar cells are exposed to extreme thermal/mechanical environment in space. In order to detect small cracks and internal damages in the solar cells due to thermal shocks, which are the core units of a solar cell system, expensive equipment, complicated test process, and much time are required. Therefore, a qualitative method for easily and quickly testing the 'health' of solar cell functionality is required. This dissertation describes a theoretical and technical grounds for quickly and easily evaluating the health of solar cells using electroluminescence effect of Gallium-Arsenide solar cells that are most widely used by spacecrafts in recent years. Also described in the dissertation is the technical issues and constraining factors for applying the proposed method to actual space-rated solar cell systems.