• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 1990.10a
• /
• pp.53-56
• /
• 1990

When oil flows and rubs against various materials in transformer, electrostatic charges are separated at the interface of the oil and the solid material. Using simplified model transformer, authors investigated the basic characteristics of the streaming electrifica-tion which is caused by forced oil circulation. As the result of the study, it was concluded that the electrostatic charge distribution on test pipe of the transformer showed larger leakage current at the inlet and the outlet.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 1990.10a
• /
• pp.41-46
• /
• 1990

This paper shows the characteristics of sparkover discharge in flowing air ranging from O(Reynolds number, Re to 10.52$\times$104(Re). Also, we investigated changes of dis-charge pattern for constant input power by adjustment of the Re. The important results obtained from this paper are as followers. The maxinum sparkover voltage of flowing air are about 6.3[kV] higher than those of static air. The discharge pattern can be controlled by adjustment of the Re.

• Proceedings of the KIEE Conference
• /
• 1991.07a
• /
• pp.466-470
• /
• 1991

In this paper, full bridge inverter with IGBT is proposed. By Controlling phase angle difference between 2 arms, PWM controlled high frequency link inverter has VVVF capability. For the simplicity, flexibility and compactness of control circuit, 16 bit single chip microcontroller 8797 BH is used and its characteristic is examined through experiment.

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.1133-1135
• /
• 1992

This paper describes high frequency inverter using zero voltage switching(ZVS). The ZVS operation is achieved to reduce the switching stress and switching loss under high speed switching. The proposed circuit configuration and performance are discussed. Its operation characteristics are evaluated through computer-aided simulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.11a
• /
• pp.357-360
• /
• 1995

Since the streaming electrification phenomena of transformer were made clear on 1970s, many researches have been continued on the improvement of the transformer. This paper describes the effect of additive (BTA, DBPC) and temperature on the streaming electrification of the various materials. The streaming current in the various materials decreases in proportion to the concentration of BTA, results in the inverse electrification. We believe that these results will contribute to the optimal design of HV large-capacity transformer.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.53 no.4
• /
• pp.207-211
• /
• 2004

We consider a class of uncertain nonlinear systems containing the uncertainties without a priori information except that they are bounded. For such systems, we assume that the upper bound of the uncertainties is represented as a Fredholm integral equation of the first kind and we propose an adaptation law that is capable of estimating the upper bound. Using this adaptive upper bound, a continuous robust control which renders uncertain nonlinear systems uniformly ultimately bounded is designed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.11a
• /
• pp.332-335
• /
• 1995

Electrification pipe modeled on the oil path of the high power transformer is designed and manufactured. Distributions of oil flow velocity are simulated as spacer form in the electrification pipe. Streaming currents are investigated as each electrification pipe. The surface oil velocity of spacer is small the streaming current.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.333-334
• /
• 2009

This study was investigated the fluidity properties of Normal concrete using Fine aggregate with Rapidly cooled Electric arc furnace oxidizing slag.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1989.06a
• /
• pp.35-36
• /
• 1989

A streaming current in liquid generated by flow electrification in a pipe is very hazardous and has to be reduced before the liquid is put into a storage tank, it was measured in pipe (${\Phi}$: 0.5mm, 0.8mm length: 1.5-11cm), it was increased as increasing pressure of Ar gas and appeared a peak value at 5cm of pipe length in 4m/sec of flow velocity.

• Proceedings of the KIEE Conference
• /
• 1998.07d
• /
• pp.1436-1437
• /
• 1998

In this paper, the result of experimental investigation into the streaming electrification phenomena of insulating oil under an external dc field effect is described. Energization by positive dc voltage enhanced the streaming electrification. but when the applied voltage was negative, the polarity of streaming current was field strength dependent.