• 한국자동차공학회논문집
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• 제8권5호
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• pp.165-172
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• 2000

The VDC(Vehicle Dynamic Control) is a control system whose target is to improve stability of a vehicle under lateral motion. A lateral vehicle motion, especially on a slippery road, can lead to a hazardous situation, and the situation can even worsen by the driver`s inappropriate response. In this paper, two VDC systems, a fuzzy-based controller and an LQR-based controller have been developed. The controllers take as input the yaw rate and the sideslip angle of either body or rear wheel, and they yield the direct yaw moment signal by which the vehicle can gain stability during cornering. Simulations have been conducted to evaluate the performance of the control system. The results indicated that the controllers can successfully improve vehicle stability under potentially dangerous driving conditions.

• 농촌지도와개발
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• 제26권2호
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• pp.57-68
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• 2019

This paper was done as an exploratory study aiming to identify the relationship between small group characteristic factors and perceived performance in the Village Development Committee (VDC) in Saemaul Undong project in Laos. The data were gathered from 166 members in 17 VDCs in Vientian province, however 135 questionnaires were used in analysis. Structure Equation Model was applied in the analysis with Amos 21. The major finding of this study were as follows; firstly decision making was more influenced by task cohesion than social cohesion, secondly organizational citizen behavior was influenced by both task cohesion and social cohesion. However, social cohesion had more influence than task cohesion, thirdly the VDC members learned their technical knowledge from decision-making process, and influenced to their perceived performance level and to VDC sustainablity, and fourthly in overall, committee members implemented their jobs based on task-oriented.

• 한국정보전자통신기술학회논문지
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• 제11권2호
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• pp.129-136
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• 2018

전 세계적으로 국제 표준인 IEC 61850 통신규약을 사용하고 있고 국내에서도 2007년도부터 시험 적용과 연구개발을 통해 2013년부터 신규 건설되는 변전소는 IEC 61850 기반의 디지털변전소로 준공되어 지고 있다. 국내 대기업을 중심으로 디지털 변전소 운영시스템 개발을 위한 연구가 진행되어 LCP용 IED 전력응용기기를 개발하였으나, 기존 변전소에 설치되어 운전 중인 구형의 현장기기와 신형인 디지털 변전소 운영시스템에 사용되는 현장기기를 모두 수용할 수 있는 시스템 분야의 연구는 아직 미흡한 실정이다. 본 논문에서는 제안된 현장정보처리반을 IEC 61850 기반으로 구성할 수 있는 48VDC 입력모듈과 125VDC 출력모듈을 구현하고 패킷 분석 툴인 IEC 61850 클라이언트 인증 프로그램과 Wireshark를 사용하여 상태감시, 제어조작시험을 실시하여 현장 적용 가능성을 검증하였다.

• 전력전자학회논문지
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• 제10권1호
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• pp.78-86
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• 2005

최근 들어, 저전압·대전류 출력 특성을 갖는 연료전지를 위한 새로운 발전시스템이 주목받고 있다. 연료전지 발전시스템에서는 dc-dc 승압용 컨버터와 dc-ac 인버터가 필요하다. 그러므로 본 논문에서는 연료전지 발전시스템을 위한 ZVS 동작을 가진 dc-dc 능동 클램프 전류형 하프 브리지 컨버터를 제안하였다. 제안된 컨버터는 일반적인 dc-dc 컨버터에 비해 높은 효율과 높은 소자 이용율을 가진다. 연료전지 발전시스템은 연료전지(PEMFC)의 낮은 전압(28∼43[Vdc])을 380[Vdc]로 승압하기 위한 능동 클램프 전류형 하프 브리지 컨버터로 구성하였다. 단상 풀 브리지 인버터는 220[Vac], 60[Hz] 교류 출력을 얻기 위해 적용하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1043-1045
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• 2002

고전압 전원공급기를 고 밀도로 제작하기 위하여 고 주파수 동작을 시켜야 한다. 이에 따라 전원 공급기에서 최대의 부피를 차지하는 부품인 변압기는 원하는 주파수에서 최소의 부피로 충분한 전력을 수용하면서 완벽한 펄스재현을 하여야 한다. 고전압 전원공급기는 풀-브릿지 DC/DC 컨버트로 구성되어 있으며 스윗칭 주파수는 100 kHz 이다. 변압기는 일차권선이 1개이며 이차 권선은 4개로 구성된다 일차전압은 250 Vdc, 이차 권선 각각의 출력은 520 Vrms이다. 변압의 이차 권선은 배 전압 회로를 이용하여 승압 후 각각을 직렬로 연결하여 -4,100 VDC와 -2,050 VDC를 만들어 TWT(Travel Wave Tube)의 케소드 및 콜렉트에 공급한다. 이 변압기는 100 kHz 펄스로 동작하고 최대부피가 400$cm^3$이하가 되어야 한다. 본 논문에서는 이러한 변압기의 설계 방법 및 최소 온도상승을 위한 적절한 동작 자속밀도의 선택에 대하여 기술하고 변압기의 누설 인덕턴스, 분포 케페시턴스, 공진 주파수에 대하여 설계치 및 실험치를 비교 평가하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.233-237
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• 2002

Vehicle Dynamics Control(VDC) has been a breakthrough and become a new terminology for the safety of a driver and improvement of vehicle handling. This paper examines the usefulness of a brake steer system (BSS), which uses differential brake forces for steering intervention in the context of VDC. In order to help the car to turn, a yaw moment can be achieved by altering the left/light and front/rear brake distribution. The steering function achieved through BSS can then be used to control lateral position in an unintended road departure system. A 8-DOF non-linear vehicle model including STI tire model will be validated using the equations of motion of the vehicle, and the non-linear vehicle dynamics. Since Fuzzy logic can consider the nonlinear effect of vehicle modeling, Fuzzy controller is designed to explore BSS feasibility, by modifying the brake distribution through the control of the yaw rate of the vehicle. The control strategies developed will be tested by simulation of a variety of situation; the possibility of VDC using BSS is verified in this paper.

• 한국정밀공학회지
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• 제20권5호
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• pp.82-91
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• 2003

Vehicle dynamics control (VDC) has been a breakthrough and become a new terminology for the safety of a driver and improvement of vehicle handling. This paper examines the usefulness of a brake steer system (BSS), which uses differential brake forces for steering intervention in the context of VDC, In order to help the car to turn, a yaw moment can be achieved by altering the left/right and front/rear brake distribution. The steering function achieved through BSS can then be used to control lateral position in an unintended road departure system. An 8-DOF non-linear vehicle model including STI tire model will be validated using the equations of motion of the vehicle, and the non-linear vehicle dynamics. Since fuzzy logic can consider the nonlinear effect of vehicle modeling, fuzzy controller is designed to explore BSS feasibility, by modifying the brake distribution through the control of the yaw rate of the vehicle. The control strategies developed will be tested by simulation of a variety of situation; the possibility of VDC using BSS is verified in this paper.

• Journal of Power Electronics
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• 제15권1호
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• pp.65-77
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• 2015

Resonant converters are well suited for induction heating (IH) applications due to their advantages such as efficiency and power density. The control systems of these appliances should provide smooth and wide power control with fewer losses. In this paper, a simple phase locked loop (PLL) based variable duty cycle (VDC) pulse density modulation (PDM) power control scheme for use in class-D inverters for IH loads is proposed. This VDC PDM control method provides a wide power control range. This control scheme also achieves stable and efficient Zero-Voltage-Switching (ZVS) operation over a wide load range. Analysis and modeling of an IH load is done to perform a time domain simulation. The design and output power analysis of a class-D inverter are done for both the conventional pulse width modulation (PWM) and the proposed PLL based VDC PDM methods. The control principles of the proposed method are described in detail. The validity of the proposed control scheme is verified through MATLAB simulations. The PLL loop maintains operation closer to the resonant frequency irrespective of variations in the load parameters. The proposed control scheme provides a linear output power variation to simplify the control logic. A prototype of the class-D inverter system is implemented to validate the simulation results.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 센서 박막재료
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• pp.35-37
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• 2001

The Al etching was studied employing negative ions generated in the downstream $Cl_2$ plasma. In order to etch the Al film practically on an insulator covered electrode coupled with RF power, reduction of the negative self bias voltage (Vdc) was examined using a magnetic filter which trapped electrons. Addition of $SF_6$ and $H_2$ to a $Cl_2/BCl_3$ mixture reduced significantly Vdc.

• Journal of Power Electronics
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• 제9권6호
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• pp.866-873
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• 2009

In general, the output voltage level of a PV array varies widely at various irradiances and temperatures. The MPP (Maximum Power Point) range of a medium- or high-power PV PCS is normally 450~830Vdc or 300~600Vdc. This means the PV PCS should operate in a wide range of modulation indexes. The PV PCS should satisfy the harmonic current requirement that the TDD (Total demand distortion) shall not exceed 5%. This paper proposes a new PWM control method for a medium- or high-power PV PCS which increases the efficiency of power conversion in all operation ranges with acceptable harmonic ripple currents. This paper compares and analyzes appropriate PWM schemes for the PV PCS in the view points of conversion efficiency and current harmonics.