• Transactions on Electrical and Electronic Materials
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• v.8 no.3
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• pp.143-146
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• 2007

Polymer insulators are used widely in variable fields for high voltage insulation and separating people from high voltage charging parts for safety and also supporting overhead power line in electric railway. But it may be broken down by tracking path resulting from continuous surface discharge. This paper has investigated synthetically both the characteristics of electrical aging using precision CT(current transformer) and the thermal aging using thermography method. Electrical aging was analyzed for time-frequency region and thermal aging was illustrated by image processing method. This synthetic method may be an appropriate one to evaluate the surface degradation of polymer insulator.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.7
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• pp.20-28
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• 2009

This paper presents the design of zero current switching ZCS pulse frequency modulation type DC-DC converter for magnetron power supply. A magnetron serving as the microwave source in a microwave oven is driven by a switch mode power supply (SMPS). SMPSs have the advantages of improved efficiency, reduced size and weight, regulation and the ability to operate directly from the converter DC bus. The demands of the load system and the design of the power supply required to produce constant power at 4[kV]. A magnetron power supply requires the ability to limit the load current under short circuit conditions. The current source series resonant converter is a circuit configuration which can achieve this. The main features of the proposed converter are an inherent protection against a short circuit at the output, a high voltage gain and zero current switching over a large range of output power. These characteristics make it a viable choice for the implementation of a high voltage magnetron power supply.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.405-407
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• 2010

Simple equivalent circuit model is developed for wireless energy transfer system via coupled magnetic resonances and practical design method is also provided. Node equations for the resonance system are built with the method expanding transformer's equations and the optimum distances of coils in the system is derived analytically for optimum coupling coefficients for high transfer efficiency. Moreover, to calculate the frequency characteristics for a lossy system the equivalent model is established at an electric design automation tool. The model parameters of the actual system are extracted and the results of modeling are compared with the measurement. Through the developed model, we can understand the principles that the system shows higher efficiency than conventional magnetic coupling systems and impedance matching is important to achieve high efficiency.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.403-404
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• 2013

In this paper, a PCS which consists of high boost interleaved full-bridge converter and single phase half-bridge inverter is proposed. Proposed PCS is using two full bridge converter modules. PCS consists of parallel input / serial output. It can reduce turn ratio of high frequency transformer. In this paper, PCS which is using 1.5[kW] interleaved full-bridge converter and single phase half bridge inverter is designed and verified stability of system through experiment.

• Journal of IKEEE
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• v.14 no.2
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• pp.9-15
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• 2010

In this study, we have been proposed the new type of a transcranial magnetic stimulation adopted a variable voltage capacitor with Cockcroft-Walton circuit and constant-frequency current resonant half-bridge inverter. This a transcranial magnetic stimulation has some merits compared with the conventional one. First, it doesn't require the high voltage transformer. And second, it has less switching losses, compact size and capability in adjusting the transcranial magnetic stimulation output energy precisely. In this paper, we have performed the output characteristics of a transcranial magnetic stimulation system which is well known as magnetic stimulation. The tested results are described as a function of pulse repetition rate and switching numbers of the half-bridge inverter.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2772-2774
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• 2003

The power source of inverter welder stable power of low voltage and high current. Because if shouldn't be, it is caused to spark between the parent metal and the peak. So that, we designed to be base on high frequency transformer and reactor of DC part. Then, we optimized control of PWM, current rising slant, voltage, current, pulse current and inverter out-put voltage. Also we designed PCB for EMI and noises.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.4
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• pp.56-64
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• 1997

최근 용접분야에서는 용접성능을 향상시키기 위하여 인버터회로를 용접기에 적용한 인버터 용접기에 관한 연구가 활발히 진행되고 있다,. 그러나 범용의 인버터 용접기의 경우 다이오드 정류기를 사용함에 저차의 전류고조파가 발생하고 시스템 역율을 저하시킨다. 따라서 본 논문에서는 인버터 아크 용접기의 역율개선을 위한 PWM 컨버터에 관하여 연구하여 입력전류의 저차 고조파를 저감하였고 전원전압과 동상으로 전원전류를 제어함에 의한 단위 역율형 인버터 용접기의 특성을 해석하였다. 또한 본 논문에서는 에너지 절약, 용접 특성, 역율, 사용율, 크기 및 부피 등의 관점에서 인버터 아크용접기의 응용연구 및 실험적 분석을 수행하였고 용접기 시스템에서 발생하는 전기적 노이즈를 억제하고 전력용 반도체 소자를 보호할 목적으로 새로운 노이즈 차폐변압기를 채택하였다. 이상의 전체시스템은 싱글칩 마이크로 프로세서를 이용한 디지털 제어기로 구현함으로서 제어기의 유연성과 기능의 다양화를 추구하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1888-1889
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• 2007

The power source of inverter welder stable power of low voltage and high current. Because if shouldn't be, it is caused to spark between the parent metal and the peak. So that, we designed to be base on high frequency transformer and reactor of DC part. Then, we optimized control of PWM, current rising slant, voltage, current, pulse current and 인버터 out-put voltage. Also we designed PCB for EMI and noises.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.15-16
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• 2016

This paper proposes an isolated DCDC converter that consists of unregulated LLC resonant converter and non-isolated synchronous buck converter for battery charger of energy storage systems application. The unregulated converter operates as transformer with fixed duty ratio and switching frequency. The synchronous buck converter is installed in the output of the LLC resonant converter. And the converter charges and discharges the battery by controlling a current of battery. The proposed converter can get the high efficiency by separating function. This paper explains design of an unregulated converter and synchronous converter.

• Journal of Magnetics
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• v.15 no.4
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• pp.213-220
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• 2010

Since the hypothalamus immediately reacts to a nerve by processing all the information from the human body and the external stimulus being conducted, it performs a significant role in internal secretion; thus, a diverse and rapid stimulus pulse is required. By detecting Zero Detector accurately via the application of AVR on-Chip (ATMEL) using commercial electricity, chopping generates a stimulus pulse to the brain using an IGBT gate to designate a new magnetic stimulation following treatment and diagnosis. To simplify and generate a diverse range of stimuli for the brain, chopping can be used as a free magnetic stimulator. Then, commercial frequency (60Hz) is chopped precisely at the first level of the leakage transformer to deliver an appropriate stimulus pulse towards the hypothalamus when necessary. Discharge becomes stable, and the chopping frequency and duty-ratio provide variety after authorizing a high-pressure chopping voltage at the second level of the magnetic stimulator. These methods have several aims. The first is to apply a variable stimulus pulse via accurate switching frequency control by a voltaic pulse or a pulse repetition rate, according to the diagnostic purpose for a given hypothalamus. Consequently, the efficiency tends to increase. This experiment was conducted at a maximum of 210 W, a magnetic induced amplitude of 0.1~2.5 Tesla, a pulse duration of $200{\sim}350\;{\mu}s$, magnetic inducement of 5 Hz, stimulus frequency of 0.1~60 Hz, and a duration of stimulus train of 1~10 sec.