• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.110-113
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• 2004

ZnO varistor ceramics which were fabricated with variation of added of $0.5{\sim}1.0mol%\;Co_3O_4$ sintered at $1150^{\circ}C$. In the specimen added $0.7mol%\;Co_3O_4$, sintered density was $6.03g/cm^3$ and electrical peoperties were superior to any other components. The nonlinear coefficient a was 83, and clamping voltage ratio was 1.35. But, endurence surge current in the specimen added $0.5mol%\;Co_3O_4$ was $7000A/cm^2$, and deviation of varistor voltage was ${\Delta}-3.23%$. As P.C.T and T.C.T environment test were succeed in all specimens, and deviation of varistor voltage in the specimen added $0.6mol%\;Co_3O_4$ was ${\Delta}-0.81%$. All specimens showed a good leakage current property in the High Temperature Continuous Load Test for 1000hr, at $85^{\circ}C$, and variation rate of the varistor voltage was ${\Delta}-2%$.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1578-1580
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• 1999

Silicone rubber is being used for the housing material of outdoor high voltage insulators such as composite insulator, bushing, surge arrestor and cable terminator because of good tracking and erosion resistance, good hydrophobicity and recovery of hydrophobicity, and chemical stability. In this paper, tracking and erosion resistance of silicone rubber having fluids and different ATH contents were examined. Fluids were selected under the consideration of their molecular weight and chemical structure, expecting the high migration rate, the good pollutant encapsulation, and the long period with good hydrophobicity. Good tracking and erosion resistance and arc resistance have been achieved for the silicone rubber above ATH content 130 phr.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.424.2-424.2
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• 2016

Solar cell converts light energy to electric energy. But a solar cell generates low power, PV module is fabricated by connected in series with dozens of solar cell. Owing to solar cell connected in series, power of PV module is influenced by shading or mismatch power of solar cells. To prevent power loss of PV module by shading or mismatch current, Bypass diodes are installed in PV module. Bypass diode operating reverse voltage by shading or mismatch power of solar cells bypass mismatch current. However, bypass diode in module exposed outdoor is easily damaged by surge voltage. In this paper, we confirm characteristics variation of PV module with damaged bypass diode. As a result, power of PV module with damaged bypass diode is reduced and Temperature of that is increased.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.222-226
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• 2001

This paper compares three kinds of soft-switching circuits from viewpoints of surge suppression, load characteristic, and power efficiency for a tapped-inductor buck converter with low voltage and high current. As a result, these soft-switching techniques have achieved much higher efficiency of $80\%$ when compared with a hard-switching buck converter for the output condition of 1V and 20A.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.171-176
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• 2010

This paper presents the electric field for 22.9[kV]/380[V], 2[MVA] mold transformer are analysed using FEM(finite element method). The electric field was calculated for the voltage applied to the transformer. Then, it is analysed that the maximum electric field occurred between high voltage turns. Capacitance is calculated with energy method. Surge impulse test simulation is studied by modeling circuit with capacitance and inductance. This paper obtain the result that is about influence of electric field in distribution mold transformer adopted.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.4
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• pp.265-272
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• 2018

This paper proposes a new control method for the supercapacitor (SC) to compensate the pulsed load and to enhance the power quality of the DC microgrid. By coordinating the operating frequency, the SC is controlled to handle the surge current, while the low-frequency current component is dealt with by the remaining sources in the system. The operation mode of the SC unit is automatically changed based on the state of charge and DC bus voltage level. Meanwhile, the mismatch in the power demand is covered by the SC unit by regulating the DC bus voltage level. The effectiveness of the proposed method is verified experimentally by the prototype with two distributed generators and one SC unit.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.673-675
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• 1992

The operation of condenser-bank is now increasing around Kyoungin area. The operation of condenser-bank is used for the improvement of under voltage and expand of power demand. But the operation has the problem in itself as the switching over voltage. This report deals with the static-condenser fault caused by abnormal operation of circuit breaker which has occurred last summer. We have analyzed this fault using EMTP(electromagnetic transient program).

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2019_2020
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• 2009

A recurrent surge oscillograph(RSO) test was performed at the Taean thermal power plant on #5 turbine generator. The test was conducted using a rotor reflectometer and digital oscilloscope. A DC voltage step is applied to each end of the rotor winding in turn. Each reflected wave, at the input end of the winding, is monitored and the two waveforms are superimposed automatically and monitored on a single channel oscilloscope. As the half windings in a rotor are identical, the two waveforms monitored at each end of the rotor will also be identical for a healthy winding. A winding with a fault will cause different voltages to be monitored at the two ends.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.418-421
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• 1989

A program for numerical analysis of induced lightning surge is developed. The program first converts simultaneous differential equations into simultaneous difference equations for line sections without transition points, and calculates the line voltage and current by solving a determinant. It, then, calculates the line voltage and current at transition points by applying kirhhoffs law. This program is potentially useful in a wide range of applications for investigating the effect on distribution lines of lightning protection equipment such as lightning arresters and overhead ground wires.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.112-112
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• 2010

The purpose of development is to localize a connector for connection of cable and GIS for underground transmission system. The cable connector for GIS provides electrical insulation of GIS housing part and makes connection of ultra high voltage electrical apparatus and power cable by controlling electrical stress between electrodes of power cable termination. Generally Korean switchgear makers are using a connector for GIS made by foreign companies. We manufactured sample by best structure design of great capacity conductor connecting part and then modified the design by analysis of shape and section. We completed the suitable sample for current cycling test condition of conductor connecting part sample and ensured surge characteristics of line by short-time current test.