• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.176-177
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• 2010

현재 학계에서는 신재생 에너지에 관한 연구가 활발히 진행되고 있으며, 그 중 태양광과 풍력이 큰 비중을 차지하고 있다. 본 논문에서는 Push-Pull 컨버터를 기초한 전류형 PWM 인버터를 제안하고 계통 연계가 가능한 회로로의 타당성을 검증하였다. 스위칭 소자 중 Push-Pull컨버터부의 두 개의 스위치만 PWM(Pulse Width Modulation)을 행하고 계통과 연결된 Full-Bridge의 스위치는 계통의 극성을 판단하여 Auto-ZCS (Zero Current Switching)가 가능하도록 설계하였다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1991.10a
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• pp.205-209
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• 1991

The conventional modeling equations for planar MOSFET can not be directly used for zero or minus junction depth concave MOSFET. In this paper, we suggest a new model which can simulate the electrical characteristics of concave MOSFET. The threshold voltage modeling was achieved using the charge sharing method considering the relative difference of source and drain depletion widths. To analyze the ID-VDS characteristics, the conventional expressions for planar MOSFET were employed with the electrical channel length as an effective channel length and the channel length modulation factor as ${\alpha}$ΔL. By comparing the proposed model with experimental results, we could get reasonably similar curves and we proposed a concave MOSFET conditiion which shows no short channel effect of threshold voltage(V${\gamma}$).

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1991.10a
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• pp.119-122
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• 1991

In this paper, a new adaptive IIR notch filter employing all pass filter is proposed. Proposed all pass filter is composed of all pole and all zero sections, each of which utilizes modulation lattice filter [11]. And, adaption algorithm for proposed notch filter is also derived. In addition, the error surface for proposed IIR adaptive notch filter is analyzed. Computer simulation results reveal that the proposed adaptation algorithm works well for low SNR(signal to noise ratio) single and multiple sinusoids. And it is shown that for estimation time varying frequency, the parameter which is related to notch bandwidth is important than any other parameters.

• Journal of Power Electronics
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• v.12 no.2
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• pp.258-267
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• 2012

An interleaved single-stage AC/DC converter with a boost converter and an asymmetrical half-bridge topology is presented to achieve power factor correction, zero voltage switching (ZVS) and load voltage regulation. Asymmetric pulse-width modulation (PWM) is adopted to achieve ZVS turn-on for all of the switches and to increase circuit efficiency. Two ZVS half-bridge converters with interleaved PWM are connected in parallel to reduce the ripple current at input and output sides, to control the output voltage at a desired value and to achieve load current sharing. A center-tapped rectifier is adopted at the secondary side of the transformers to achieve full-wave rectification. The boost converter is operated in discontinuous conduction mode (DCM) to automatically draw a sinusoidal line current from an AC source with a high power factor and a low current distortion. Finally, a 240W converter with the proposed topology has been implemented to verify the performance and feasibility of the proposed converter.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.147-150
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• 2002

HPSL(High Pressure Sodium lamp)have attracted much attention in recent years, because they offer high luminous efficiency and very long life. Recently, AC-DC converters have been widely as power factor improvement circuits in the power conversion equipment An application of the ZVT-PWM(Zero Voltage Transition Pulse Width Modulation) boost converter, which has great advantage on miniaturization and high power density, to the power factor improvement circuit of the HPSL inverter are described to identify the power factor correction characteristics of the inverter. In this paper the series-parallel resonant inverter(electronic ballast) for driving a HPS lamp is discussed. Finally, a power factor corrector is cascaded in front of the electronic ballast. Consequently, a high power factor above 0.99 and low THD on the line current can be achieved.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.355-357
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• 1999

Single-Phase multi-level AC-DC converter that is composed of diode bridge and switch is proposed. The number of the supply current level is depending on the individual current level of the converter. A converter circuit, the number of the level is equal to $2^{M+1}-1$, where M is the number of Switching Converter. The proposed circuit has converter with 31 current levels. When the number of current level is increased, smoother sinusoidal waveform can be obtained directly and it is possible to control the supply current almost continuously from zero to maximum without generating high voltage step changes as pulse with modulation technology. The technique illustrates its validity and effectiveness through the PSIM.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.234-236
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• 2003

In this paper, a new control scheme of Class-E inverter for reducing the crest factor of electronic ballasts for fluorescent lamps using Pulse-Frequency-Modulation (PFM) is introduced The lifetime of the lamps is guaranteed by decreasing the lamp crest factor and voltage stress of the switch is significantly decreased by a new scheme although conventional Class-E inverter is used in this paper The proposed PFM control scheme doesn't used any auxiliary circuit. The proposed control strategy is executed by feeding back the input current. and the Zero-Voltage-Switching (ZVS) is ensured by operating beyond resonant frequency. Therefore, the control principles of proposed method are explained in detail and its validity is verified through several simulated results.

• Journal of Satellite, Information and Communications
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• v.2 no.1
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• pp.7-13
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• 2007

A new and effective Doppler effects compensation method based on constellation estimation as well as an average power saving strategy by modified modulation scheme utilizing zero point constellation are presented with theoretical analysis and relevant simulations. The suggested schemes are proved to be very effective for satellite OFDM signals relayed by power limiting transponder for the mobile terminal on high speed vehicles.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.11
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• pp.1-10
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• 1993

A Study on New Digital In this paper, we propose a new Angular Form Carrier Recovery Loop(AFCR loop) for PSK modulation technique. AF CR loop includes detected angle symbol and Multi Level Hardlimiter. Using zero crossing DPLL, we model 1st 2nd AF CR loop, and also derive SCurve. In order to prove steady state operation of AF CR loop, we evaluate performance of this loop by Monte-Carlo and analytical simulation method. We also compare the performance of AF CR loop to that of other loop in terms of acquisition, S-Curve, and RMS jitter. From the comparison result, we verify that the performance of AF CR loop operates well in steady state.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1296-1299
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• 2000

A single stage AC/DC converter based on a full bridge topology suitable for high frequency soft switching converter applications is proposed. The proposed converter has high power factor, zero voltage switching, low noise and high efficiency. A pulse width modulation control is employed to reduce the switching and rectification losses respectively. This proposal converter has simple structure and low cost, The modelling and detailed analysis are performed to derive the design equations, a prototype converter has been designed and experimented. The new converter is attractive for high-voltage, high-power applications where IGBT's are predominantly used as the power switches. The principle of operation, features, and design are verified on a 1.5kW, 30kHz, IGBT based experimental circuit.