• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.250-253
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• 2003

In this paper, a characteristics and points of Guassian pulse using UWB system is analyzed, the TDMG pulse is proposed that originated ultra wide band signal without pulse width reduction. It is showed that TDMG pulse character compare with Gaussian pulse through computer simulation. And it is verified that decreased a interference of other communication systems

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.148-149
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• 2007

In this paper, an advanced torque control scheme of SRM using DITC(Direct Instantaneous Torque Control) and PWM(pulse width modulation) is investigated. The proposed DITC-PWM regulates a duty ratio of the phase switch according to the torque error and simple control rules of DITC without any hysteresis bandwidth. The proposed control method is verified by the simulations and experimental results.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.205-211
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• 2000

Friction control is highly desirable for optimization of tribological systems. In this work, the effect of geometric structure of the solid surface on friction is investigated using a Scanning Electron Microscope equipped with a tribotester. Silicon and silicon oxide specimens were used and undulations on the surface were fabricated by mechanical and chemical methods. It is shown that the friction coefficient depends on the relative dimensions of the ball and the width of undualation. By optimizing the geometry of the undulation, friction reduction may be achieved.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.106-108
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• 2020

This paper introduces a new pulse-width modulation (PWM) method to reduce common-mode voltages (CMVs) and compare its performance with other reduced CMV-PWM (RCMV-PWM) methods. To avoid the use of zero-vectors which cause high CMV peaks, the introduced method splits every reference vector into two vectors such that the peak-to-peak magnitude of CMV is reduced by one-third of conventional space-vector PWM (SVPWM). The performance of RCMV-PWMs altered by the modulation index are analyzed with simulation results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.298-299
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• 2020

Triple Active Bridge 컨버터의 경부하 조건에서의 효율 개선을 위해 브리지의 듀티와 위상을 동시에 변경하는 Dual Pulse Width Modulation(DPWM)기법을 적용하였다. 기존의 위상천이기법은 제어가 단순한 장점이 있으나 경부하 조건에서 효율이 급격히 감소하는 단점이 존재한다. 따라서 본 논문에서는 DPWM 방식을 통해 경부하 조건의 효율 개선을 위한 각 브리지 듀티, 위상각을 분석하였고, 시뮬레이션을 통해 이를 검증하였다.

• 한국지반공학회지:지반
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• 제10권2호
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• pp.121-140
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• 1994

본 연구에서 경계가 불규칙하고 여러 토층으로 이루어진 자연과 인공 사면에 대한, 토층의 경계에서 굴절하는 대수나선곡선을 파괴면으로 가정한 신뢰도해석 모델을 개발하였다. 이 모델에서, 사면파괴토괴는 양 끝단이 수직평면으로 된 일정한 폭을 가진 Cylindroid로 가정하여 절편법을 적용하였고, 강도정수의 공간적인 변화, 불충분한 시료의 수에 의한 오차 그리고 실험실과 현장조건의 차이에서 오는 모델오차를 고려하여, FOSM 그리고 SOSM의 방법으로 신뢰도 지수를 구하여 파괴확률을 구하는 프로그램을 개발하였다. 이러한 연구를 기초로 다음의 결과를 얻었다: (1) 내부마찰각의 변동계수가 점착력의 변동계 수보다 민감하게 영향을 미침을 보여주었다. 따라서 대수나선파괴면의 사면안정해석에서 내부마 찰각의 불확실성이 사면안정에 더 큰 영향을 주므로 내부마찰각의 추정에 더 큰 주의를 기울여야할 것으로 사료된다. (2) 지진이 없을 경우에는, 사면폭이 증가함에 따라 전체 3차원파괴확률과 한계파괴폭은 증가하였으며, 지진이 있을 경우에는 전체 3차원파괴확률은 증가하였으나 한계 파괴폭은 전체 사면폭이 비교적 클 때, 진도가 커짐에 따라 급격히 감소하였다. (3) 지하수위는 높을수록, 전단강도와 수정계수는 작을수록 사면의 한계폭을 감소시키는 효과가 있다.

• 전기학회논문지
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• 제57권6호
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• pp.959-965
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• 2008

This paper presents a novel method for cogging torque reduction of interior type permanent magnet motor. For calculation position and width of notch, energy formulation and cogging torque function in air gap are analyzed by analytical method(space harmonics method) and numerical method. The optimal shape of notchs is decided by using finite element method. The validity of the proposed method is confirmed with experiments.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권3호
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• pp.177-185
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• 2000

In this study, the characteristics of various electricity and high resistivity ash collection were measured at superimposed nanosecond pulse energization. The pulse was generated through the hydrogen thyratron. Superimposed pulse was nanosecond duration pulse that had fast pulse rising time 100[ns], short pulse width 500∼850[ns] and pulse fall time 400∼750[ns]. The results of this study are summarized as followings; Frist, compared with the DC ESP(electrostatic precipitator), superimposed pulse ESP could induce higher peak voltage, and had the about 30[%] reduction of ESP collection area and 50∼80[%] reduction of power consumption. showing the same efficiency. Second, enhancement factor H had 1.9∼3.6 with the increase of migration velocity.

• Journal of Power Electronics
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• 제14권2호
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• pp.362-368
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• 2014

This paper proposes a harmonic reduction approach for a pulse width modulation (PWM) AC-AC converters using Bee Colony Optimization (BCO). The optimal switching angles are provided by BCO to minimize harmonic distortions. The sequences of the PWM switching angles are considered as a technical constraint. In this paper, simulation results from various optimization techniques including BCO, Genetic Algorithm (GA), and Particle Swarm Optimization (PSO) are compared. The test results indicate that BCO can provide a better solution than the others in terms of power quality and power factor improvement. Lastly, experiments on a 200W AC-AC converter confirm the performance of the proposed switching pattern in reducing harmonic distortions of the output waveform.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.129-132
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• 2007

Advanced structure of metal-supported solid oxide fuel cells was devised to overcome sealing problem and mechanical instability in ceramic-supported solid oxide fuel cells. STS430 whose dimensions were 26mm diameter, 1mm thickness and 0.4mm channel width was used as metal support. Thin ceramic layer composed of anode(Ni/YSZ) and electrolyte(YSZ) was joined with STS430 metal support by using a cermet adhesive. $La_{0.8}Sr_{0.2}Co_{0.4}Mn_{0.6}O_{3}$ perovskite oxide was used as cathode material. It was noted that oxygen reduction reaction of cathode governed the overall cell performance from oxygen partial pressure dependance.