• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.731-735
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• 1993

When induction motor is driven with a load commutated inverter, the output part of the inverter must be capacitive. But, in order to be a good load commutation at the low speed range, very large capacitor or force commutated circuit must be used regarding the capacity of motor. This paper proposed the force commutated circuit for driving the motor in case of the installation of capacitor which can be capable of load commutation at the rating speed. The force commutated circuit is operated by the LC resonant circuit, auxiliary source and SCR, and also composed of the commutation circuit which control the interval of the inverse voltage across the inverter.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.223-225
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• 2005

This paper presents a novel prototype of a current source resonant inverter using insulated gate bipolar transistors for driving a streamer reactor, streamer generation technology has been recognized as one of the best methods for water treatment, disinfection, industrial wastes utilization, and so on. However, some technological difficulties related to efficient streamer production have been significant problems restricting streamer usage in the industrial plants. Introduced in this paper is a pulse density modulated high frequency inverter for a plasma generate, which is developed with the aim to improve power conversion and control characteristics of the streamer reactor by using advances in power electronic technology. The developed system implements the feedforward control-based pulse density modulation control scheme with pulse width modulation feedback control strategy to compensate temperature and other environmental influences on streamer discharge.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1503-1505
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• 2005

The Cold cathode fluorescent lamp(CCFL) are widely used to illuminate the liquid crystal display(LCD). Ballasts are required for CCFL because the lamp need high starting voltage and behave negative dynamic resistant characteristics in the desired region of operation. Dimming methods of CCFL are used to pulse frequency modulation(PFM) or pulse width modulation(PWM). In this paper, CCFL driving and control circuit is designed by half-bridge type series and parallel resonant inverter that variable frequency modulation method to control the output voltage current. The validity of this study is confirmed from the simulation and experimental results.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.428-430
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• 1995

In all areas of power electronics, power conversion technology is a substantial need for increasing the performance and high power semiconductor technology is rapidly developing fast switching power devices with increasing voltage and current limits. This paper described a study on the series resonant inverter using power MOSFET and its application.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.817-823
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• 2010

Design of IPI feeding structure affecting the antenna gain improvement of mobile phone was investigated. IPI feeder which based on the T matching theory increase line current for internal antenna such as IFA. So IPI feeder makes higher radiation resistance, and also increases the gain with increasing radiation efficiency. To verify IPI feeding effect, feeder is applied to conventional CDMA/DCS dual band IFA. Measurement shows that IPI-IFA has 0.5 ~ 1.4[dBi] higher gain than conventional IFA at CDMA/DCS band. Resonant frequency did not change.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.5-6
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• 2016

This paper introduces a high efficiency bidirectional resonant converter using an additional LC auxiliary circuit for dcdistribution applications. The LC auxiliary circuit operates as a variable inductor and the additional LC circuit helps to increase the effective magnetizing inductance, thereby reducing the turn-off and primary circulating current. A 5 kW bidirectional converter for dc-distribution system is implemented to verify the validity of the proposed method. The experimental results show the high efficiency characteristics of the proposed converter over the wide range of load in both direction of power flow. The maximum efficiency of the proposed system was 98.1 % at 3 kW.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.11-12
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• 2010

본 논문은 LCL필터를 이용한 분산전원용 계통연계형 PCS의 전류제어기를 비교 분석하였다.주요 비교대상은 PI(Proporional-intergral)제어,PR(Proportional-Resonant),제어기, DeadBeat (DB)제어기 등의 선형 제어기 이며, 각 제어기의 과도상태 응답특성과 정상상태 응답특성을 시뮬레이션으로 비교하였다. 또한 DSP의 특성에 의한 1 주기 지연, 리액턴스와 저항 변화 등에 강인한 DB제어기 관하여 논의 하겠다.

• Current Optics and Photonics
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• v.3 no.1
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• pp.40-45
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• 2019

Adding tunability to biological light emitters offers an unprecedented technique in biological sensing and imaging. Here, we report a tunable, lithographic-free, planar, and ultrathin metal-insulator-metal (MIM) resonator capable of tuning the optical properties solely by a silk/sodium fluorescein hydrogel layer, a biocompatible light emitter. In water, the volume of the resonator was expanded by swelling, and then the resonant mode could be shifted. Simulations predicted the red-shifted resonance peak in transmission when the MIM was swollen in water. The red-shift could be attributed to the increase in the thickness of the silk hydrogel layer due to the absorbed water. The shift of the resonance could affect the fluorescence of the dye in the silk hydrogel layer.

• Journal of the Semiconductor & Display Technology
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• v.17 no.3
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• pp.21-26
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• 2018

In this paper, the switching characteristics of the active clamp type flyback converter, which is deemed suitable for the miniaturization of the external power supply for home appliance, were analyzed and the process of reducing the switching loss was explained. The active clamp type flyback converter operating in the DCM has confirmed that the surge voltage of the main switch does not occur and the turn-off / on loss of the switch do not occur in principle. Also, in the case of the switch for synchronous rectifier, it was showed that the switch current showed half-wave rectified sinusoidal characteristic, and the switching loss was reduced. The switching characteristics of the experimental results gathered from 120 W class prototype were compared with the theoretical waveform in the steady-state and it was confirmed that the power conversion efficiency of the active clamp type flyback converter was maintained high due to the reduction of the switching loss.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.95-97
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• 2019

이 논문은 넓은 출력 전압 범위를 조절할 수 있는 새로운 듀얼 하프 브리지 LLC 공진 컨버터를 제안한다. 제안된 컨버터는 전압 더블러 모드와 전압 쿼드러플러 모드 두 가지 작동모드를 사용함으로써 좁은 스위칭 주파수 변동 범위에서도 넓은 출력 전압 범위를 조절할 수 있다. 또한 새로운 정류기 구조를 제안함으로써 출력 커패시터의 출력 전류 리플을 감소시켜 출력 커패시터의 크기를 감소시킨다. 따라서 제안된 컨버터는 넓은 출력전압 범위를 조절할 수 있으면서 높은 전력 밀도를 달성할 수 있다.