• 대한인간공학회지
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• 제8권2호
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• pp.43-47
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• 1989

An instrumentation system to measure the pressure between elastic bodies and between an elastic and a rigid body has been developed. The force between elastic bodies can be measured only by Elastric- body pressure Meter. As a standard Elastic-body pressure Meter, Model RCG-24A consists of 24 pick-ups, one switch box and one amplifier and measuring is possible at each of 24 measuring spots by swithing one to the nest using the switch box. The system can be used in various specialized disciplines, such as ergonomics, anthropometry and biomechanics.

• 전력전자학회논문지
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• 제17권4호
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• pp.298-305
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• 2012

This paper proposes a soft switching boost converter with an auxiliary resonant circuit. The auxiliary resonant circuit is added to a general boost converter and that is composed of one switch, one diode, one inductor and two capacitors. The resonant network helps the main switch to operate with a zero voltage switching(ZVS) and auxiliary switch also operates under the zero voltage and zero current conditions. The soft switching range is extended by the auxiliary switch and it is possible to control the proposed converter with a pulse width modulation(PWM). The ZVS and ZCS techniques make switching losses decreased and efficiency of the system improved. A theoretical analysis is verified through the simulation and experiment.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권3호
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• pp.188-194
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• 2000

This paper presents new Zero-Voltage-/Zero-Current-Switching (ZVZCS) PWM DC-DC converters. The proposed soft-switching technique achieves ZVS and ZCS simultaneously at both turn-on and turn-off of the main switch and diode by using only one auxiliary switch. Also, the proposed soft-switching technique is suitable for not only minority but also majority carrier semiconductor devices. The auxiliary circuit of the proposed topology is placed out the main power path and therefore, there are no voltage/current stresses on the main switch and diode. The operating principle of the proposed topology is illustrated by a detailed study with a boost converter as an example. Theoretical analysis, simulation and experimental results are presented to explain the proposed schemes.

• 인터넷정보학회논문지
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• 제5권3호
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• pp.45-56
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• 2004

본 논문에서는 네트워크가 많은 endpoint를 가질지라도 낮은 비트율의 데이터를 효율적으로 전송할 수 있는 AAL 유형 2 스위치를 포함하는 ATM스위치 구조를 제안한다. 컴퓨터 프로그램으로 모델링한 ATM스위치는 AAL 유형 1, AAL 유형 2, AAL 유형 3/4 및 AAL 유형 5 셀로 이루어진 모든 유형의 AAL 셀에 대해 셀 스위칭을 지원하고 있다. 우리는 2가지 방식의 스위치를 제안하고 있는데, 하나는 개별적인 입력 포트마다 AAL 유형 2 셀 처리를 지원하는 스위치 패브릭이고, 다른 하나는 모든 입력 포트에 대한 전체적인 AAL 셀 처리를 지원하는 스위치 패브릭이다. 시뮬레이션 결과는 후자의 방식이 전자의 방식보다 우수한 것으로 나타났다. 그러나, 전자의 방식이 구현이 용이하고, 확장성에 대한 장점을 가지고 있다. 따라서 본 논문에서는 전자의 방식을 채용한 AAL 유형 2 스위치 모듈을 VHDL 언어를 사용하여 설계하였으며, 이를 FPGA로 구현하였다. 설계된 칩은 52MHz에서 동작하였다. 본 논문의 ATM 스위치 패브릭은 범용의 ATM 스위치 패브릭으로서 뿐만 아니라 ATM 네트워크상으로 모바일 통신, 협대역 서비스 및 무선 ATM등에 폭넓게 응용될 것으로 사료된다.

• 한국통신학회논문지
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• 제21권1호
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• pp.119-130
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• 1996

This paper is the part I of the full study about improved structure of fully interconnected ATM switch to develop the small sized switch element and practical implemention of switch network. This part I paper describes about proposed switch structure, performance evaluations and some of considerations to practical implementation. The proposed structure is constructed of two step buffering scheme in a filtered multiplexer. First step buffering is carried out by small sized dedicated buffers located at each input port. And second step buffering is provided by a large sized common buffer at the output port. To control bursty traffic, we use speed up factor in multiplexing and priority polling according to the levels of buffer occupancy. Proposed structure was evaluated by computer simulation with two evaluation points. One is comparision of multiplexing discipline between hub polling and priority polling. The ogher is overall which should be considered to improve the practical implementation.

• Journal of Power Electronics
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• 제7권4호
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• pp.301-309
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• 2007

The flyback converter is one of the most attractive isolated converters in small power applications because of its simple structure. However, it suffers from high device stress, large transformer size, and high voltage stress across its switch and diode. To solve these problems a new cost-effective PWM single-switch isolated converter is proposed. The proposed converter has no output filter inductor, reduced voltage stress on the secondary devices, and reduced transformer size. Moreover, the switch turn-off loss is reduced and no dissipative snubber across the secondary diode is required. Therefore, it features a simple structure, a low cost, and high efficiency. The operational principle and characteristics of the proposed converter are presented and compared with the flyback converter and then verified experimentally.

• Journal of Power Electronics
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• 제7권4호
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• pp.318-327
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• 2007

The design and performance analysis of a power factor corrected (PFC), single-phase, single switch flyback buck-boost ac-dc converter is carried out for low power battery charging applications. The proposed configuration of the flyback buck-boost ac-dc converter consists of only one switch and operates in discontinuous current mode (DCM), resulting in simplicity in design and manufacturing and reduction in input current total harmonic distortion (THD). The design procedure of the flyback buck-boost ac-dc converter is presented for the battery charging application. To verify and investigate the design and performance, a simulation study of the flyback buck-boost converter in DCM is performed using the PSIM6.0 platform. A laboratory prototype of the proposed single switch flyback buck-boost ac-dc converter is developed and test results are presented to validate the design and developed model of the system.

• Transactions on Electrical and Electronic Materials
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• 제14권3호
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• pp.116-120
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• 2013

This paper proposes a novel RF MEMS dc-contact switch with stiff membrane on a quartz substrate. The uniqueness of this work lies in the utilization of a seesaw mechanism to restore the movable part to its rest position. The switching action is done by using separate pull-down and pull-up electrodes, and hence operation of the switch does not rely on the elastic recovery force of the membrane. One of the main problems faced by electrostatically actuated MEMS switches is the high operational voltages, which results from bending of the membrane, due to internal stress gradient. This is resolved by using a stiff and thick membrane. This membrane consists of flexible meanders, for easy movement between the two states. The device operates with an actuation voltage of 6.43 V, an insertion loss of -0.047 dB and isolation of -51.82 dB at 2 GHz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술대회 논문집 전문대학교육위원
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• pp.158-161
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• 2003

A new soft switching technique that improves performance of the high power factor boost rectifier by reducing switching losses is introduced. The losses are reduced by air active snubber which consists of an inductor, a capacitor a rectifier, and an auxiliary switch. Since the boost switch turns off with zero current, this technique is well suited for implementations with insulated gate bipolar transistors. The reverse recovery related losses of the rectifier are also reduced by the snubber inductor which is connected in series with the boost switch and the boost rectifier. In addition, the auxiliary switch operates with zero voltage switching. A complete design procedure and extensive performance evaluation of the proposed active snubber using a 1.2[kW] high power factor boost rectifier operating from a $90[V_{rms}]$ input are also presented.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권2호
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• pp.79-85
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• 2001

In this paper, a novel Zero-Current-Transition (ZCT) technique, which provides Zero-Current-Switching (ZCS) turn-off of the main switch, the main diode and the auxiliary switch, is presented. The proposed auxiliary circuit consists of minimum elements only one auxiliary switch, resonant inductor and resonant capacitor. Also the reduced di/dt, which is obtained by resonant inductor, helps soft turn-on of the main switch. Besides, to eliminate the additional conduction loss and current stress on main switch, a topological variation was performed. The theoretical analysis and the operation principle of the new ZCT techniques are described in detail with a boost converter as an example. To verify the validity of the proposed ZCT techniques, the simulation and the experiment were performed under 1kW output power and 100kHz switching frequency.