• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.31-33
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• 1991

A passive power converter operating on the principle of parametric excitation, called Parametric transformer, is analyzed. The energy transfer from the input to the output is achieved through the double frequency variation of magnetic path reluctance to the input frequency without mutual flux coupling between two windings. Thus, output becomes available which is essentially independant of waveform of excitation. The mathmatical model of the device is developed and its solution is obtained. The outstanding characteristics of the device is explained from the analysis.

• Journal of Power Electronics
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• v.8 no.3
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• pp.239-247
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• 2008

This paper presents the design of 1 kW prototype high frequency link boost half bridge inverter-fed DC-DC power converters with bridge voltage-doublers suitable for small scale PEM fuel cell systems and associated control schemes. The operation principle of this converter is described using fuel cell modeling and some operating waveforms. The switching mode equivalent circuits are based on simulation results and a detailed circuit operation analysis at soft-switching conditions.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.382-384
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• 1994

This paper proposed a novel High Frequency resonant inverter having drive signal phasor shift control function. The operating characteristics of this inverter circuit are discussed from a thereotical point of view and comparated with experimental results.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.159-162
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• 2000

In his paper the principle of using coreless printed circuit board (PCB) based transformer in 2.3MHz, 12W class ZVS Forward DC-DC converter has been successfully demonstrated. With no core loss coreless PCB transformer and inductor are found to have favorable characteristics at high frequency operations. The maximum power conversion efficiency is 80% Even for high operating frequency an efficiency greater than 70% can be obtained with under 0.7% regulation error.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.381-384
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• 1988

This paper analysed basic operation in Zero-voltages-switching quasi-resonant buck converter and considered steady state characteristics. Especially, it is confirmed that converter operating at maximum 1MHz switching frequency in load characteristics. In this paper, a novel slope method is proposed and implemented in regulation characteristics analysis. It is proved that experimenental results coincide with theory results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.1
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• pp.7-12
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• 1983

When emergency lighting using a D.C. source is needed, we select the fluorescent lamp that has higher efficiency than that of an incandescene lamp. This paper deals with a series inverter for a fluorescent lamp load, which has high frequency output characteristics. First, the appropriate operating frequency is determined and second, the optimum value of circuit elements is determined in consideration of several important conditions. The results obtained by experimentations are represented.

• Tribology and Lubricants
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• v.16 no.4
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• pp.274-281
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• 2000

In this paper, linearized dynamic characteristics of parallel line pivoted pad thrust bearing (here-inafter refer to PLP thrust bearing) was analyzed by perturbation method with inlet pressure. Inlet pressure and excitation frequency influence dynamic characteristics of PLP thrust bearing at all operating conditions, such as angular pivot position, mass of pad. Therefore, the characteristics have to be analyzed with inlet pressure, excitation frequency, mass of pad and thickness of pad. Otherwise, the analysis may be over or under estimate.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.456-459
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• 1999

This paper presents about EL(electroluminescent) driver with inverter. Inverter is composited two FET to increase safety output voltage. As result this study, the optimum operating condition of inverter is that the gate bias frequency of FET equal two resonant frequency of circuit. It shows to ideal sinusoidal output wave. Finally, EL sampler(15cm$\times$15cm) gain 2.6 [lux] with 1cm.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.332-336
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• 1989

This paper describes the nonlinear analysis and effectual operation methods of thermal power plant turbine control system. When the turbine control governor system has dead-zone characteristic, the effectual frequency development control is difficult, because turbine output does not correspond to frequency deviation in dead-zone. Therefore to obtain effectual correspondance, the turbine dead-zone characteristic must be analyzed by proper method. This paper proposes this nonlinear analysis and effectual plant operating load.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.94-96
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• 1993

At an operating point of the induction motor, there are many sets of stator frequency and voltage. This paper presents an algorithm to determine the stator frequency and voltage which maximizes the power factor without any informations of motor parameters. Improvement of efficiency us also expected due to high-power-factor operation.