• 조명전기설비학회논문지
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• 제22권3호
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• pp.15-26
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• 2008

This paper proposes a new sinusoidal rectifier which improves input factor and input current waveform without complicated switching modulation such as pulse width or a complicated feed back control. The proposed rectifier consists of a pair of capacitors connected in series, a full bridge diode rectifier, a pair of inductors, and a pair of switching devices connected in series. While the configuration of the sinusoidal rectifier is simple in itself, it effectively reduces the reactive power and harmonics involved(IEC555-2 SC77A90 Class C) in input line current. The excellent properties of the new sinusoidal rectifier are verified by theoretical analysis and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.19-21
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• 2007

This paper proposes an input waveform improvement using VIENNA Rectifier(three-phase/level/switch). VIENNA Rectifier is based on the combination of a three-phase diode bridge and dc/dc converter. It features low input current ripple and sinusoidal mains current form.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.556-560
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• 2001

In this paper, a soft-switching discontinuous mode (DCM) power factor corrected (PFC) converter is analyzed by applying the double Fourier series expansion. It is found that the fundamental component and higher-order harmonics included in the input current waveform are obtained by the Fourier series expansion of the mean value of the inductor current. From the theoretical analysis, a new method removing the distortion of the input current waveform is proposed. In spite of an open loop system, the proposed method makes a great improvement of the total harmonic distortion even if the ratio of output voltage to input voltage is very low.

• 조명전기설비학회논문지
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• 제17권1호
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• pp.116-123
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• 2003

본 논문에서는 SMPS의 교류 입력측 역률을 개선시킬 수 있는 전치 레귤레이터로서 interleaved 승압형 컨버터를 관하여 연구하였다. Interleaved 승압형 역률보상 컨버터(IBPFC)는 입력전류를 두 개의 스위칭 소자에 의하여 50%씩 나누어져 흐르게 함으로써, 내부 전류제어 루프 얼이 전압제어 루프만으로 제어계를 구성하여 입력전류 리플을 줄일 수 있다. 즉, IBPFC를 구성하는 각각의 부스트 컨버터 cell을 불연속 전류모드로 동작시키더라도 전체적인 입력전류의 파형은 연속이 되어 입력전류 리플이 감소하게 된다. 불연속 전류모드로 동작하는 IBPFC를 해석하기 위하여 스위칭 상태에 따라서 6개의 모드로 구분하여 상태방정식을 구하였다. 또한, 각 상태방정식을 상태공간 평균화법을 이용하여 모델링하고, 미소변동분을 고려한 소신호 해석을 통하여 제어전달함수를 구할 수 있다. 또한, 제어전달함수를 이용하여 단일 전압제어 루프를 가지는 제어계를 설계하였으며, 이러한 해석 및 설계를 바탕으로 실험을 통하여 IBPFC의 역률개선 및 리플저감을 확인하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권7호
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• pp.343-351
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• 2003

In this paper, interleaved boost converter is applied as a first-stage converter in switch mode power supply. The first-stage converter plays a role to improve power factor. Interleaved Boost Power Factor Corrector(IBPFC) can reduce input current ripple as a single voltage control loop only without inner current loop, because input current is divided each 50% by two switching devices. Each converter cell is also operated in discontinuous current mode and inductor current of each converter is discontinuous. Total input current which is composed by each converter cell is continuous current. Thus, IBPFC is able to improve input current ripple. IBPFC operating in discontinuous current mode can be classified as six modes from switching state and be carried out state space averaging small signal modeling. A control transfer function is obtained according to the modeling. Not only steady-state characteristics but also dynamic characteristics is considered. Single voltage control loop is also constructed by the control transfer function. From experimental result, improvement of power factor and input current ripple are verified.

• 전기학회논문지
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• 제58권2호
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• pp.363-368
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• 2009

In the paper, we confirmed improvement Noise figure of the entire RF front-end using spiral inductor with PGS(Patterned Ground Shield) and current bleeding techniques. LNA design is to achieve simultaneous noise and input matching. Spiral inductor in input circuit of LNA inserted PGS for betterment of Q-factor. we modeling inductor using EM simulator, so compared with inductor of TSMC 0.18um. We designed and simulation the optimum structure of PGS using Taguchi's method. We confirmed enhancement of noise figure at LNA after substituted for inductor with PGS. Mixer designed using current bleeding techniques for reduced noise. We designed LNA using inductor with PGS and Mixer using current bleeding techniques, so confirmed improvement of noise figure.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.432-435
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• 1997

This Paper proposes a novel sinusoidal converter which improves input power factor and input current waveform without any complicated switching modulation such as a pulse width modulation or a complicated feed-back control. It is composed of a full bridge diode, a pair of capacitors, a pair of inductors and a pair of switching devices. The configuration and control strategy are both simple however, the sinusoidal converter effectively reduces reactive power and hamonics included in a input line current. Excellent behavior of the proposed converter is verified by theoretical analysis and experimental results.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.107-112
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• 2002

Ferritic stainless steels would be the most important alloys under the chloride environment. They are a cheaper alternative to austenitic stainless steels [1]. The present study is related to gas tungsten arc welding (GTAW) characteristics of Type 444 stainless steels. The heat of welding leads to grain coarsening in the HAZ and in the weld metal of ferritic stainless steels because they solidify directly from the liquid to the ferritc phase without any intermediate phase transformation. It is therefore recommended that these alloys be welded with a low heat input and at high welding speeds. Attempts to improve weldability were made by using of direct current straight polarity (DCSP) and pulsed current GTAW processes in this study. Measuring weld bead, grain size and Erichsen test were performed and the effects of heat input, pulse frequency on the weld metal and HAZ were studied. The main results were obtained as followings: decreasing heat input was effective to control the width of weld both in DCSP welding and in pulsed current welding; pulsed current welding was found to refine the grain size effectively and the finest grain size was found at the frequency of 150Hz in pulsed current welding; it was found that decreasing heat input also refine the HAZs effectively and the frequency had no different effect on HAZ at the same heat input; the ductility could be improved effectively in pulsed current welding.

• 한국전자통신학회논문지
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• 제3권2호
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• pp.79-85
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• 2008

다양한 무선통신 방식이 출현함에 따라 배터리 수명과, 저전력 동작이 중요시되면서 무선 통신용 LSI는 SI circuit을 이용하는 analog current-mode signal processing을 주목하고 있다. 그러나 SI (Switched-Current) circuit을 구성하는 current memory는 clock-feedthrough의 문제점을 갖는다. 본 논문에서는 current memory의 문제점인 clock-feedthrough의 일반적인 해결방안으로 CMOS switch의 연결을 검토하고, current memory 성능 개선의 설계방안을 제안하기 위하여 CMOS switch 간의 width의 관계를 도출하고자 한다. Simulation 결과, memory MOS의 width가 20um, input current와 bias current의 ratio가 0.3, CMOS switch nMOS의 width가 2~6um일 경우에 CMOS switch 간의 width는 $W_{Mp}=5.62W_{Mn}+1.6$의 관계로 정의되고, CMOS switch nMOS의 width가 6~10um일 경우에 CMOS switch 간의 width는 $W_{Mp}=2.05W_{Mn}+23$의 관계로 정의되는 것을 확인하였다. 이 때 정의된 MOS transistor의 관계는 memory MOS의 성능향상을 위한 설계에 유용한 지침이 될 것으로 기대된다.

• 전력전자학회논문지
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• 제26권4호
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• pp.302-305
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• 2021

Selection of the optimal inductance for power factor improvement of a buck AC/DC light-emitting diode (LED) driver with wide input voltage range is described in this study. The power factor change based on the slope compensation is obtained for various normalized output current (NOC) values using discrete-time domain analysis. The possibility of implementing constant slope compensation is described using power factor curves for various NOC values. NOC = 0.5 is chosen for the value of inductance with consideration for the simple implementation and reduction of inductor size. Experimental results of the inductance corresponding to NOC = 0.5 are presented.