• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.67-70
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• 2006

This paper deals with a single crystalline silicon (SCS) RF MEMS switch for telecommunication system applications. The proposed SCS switch was fabricated using a silicon-on-glass (SiOG) process and its performances in terms of RF responses, switching time, lifetime were characterized. The proposed SCS switch consists of movable plates, mechanical spring structures, which are composed of robust SCS, resulting in mechanically good stability, The measured actuation voltage was 30 V, and with this applied voltage, the insertion loss and isolation characteristics were measured to be 0.05 and 44.6 dB at 2 GHz respectively. The measured switch ON and OFF time were 13 and $9{\mu}s$, respectively. The lifetime of the fabricated switch was tested. Even after over 1 billion cycles repeated ON/OFF actuations, the switch maintained its own characteristics.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2000.02a
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• pp.35-38
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• 2000

A preliminary design of gas-gp thermal switch is presented to reduce the cooldown time of superconducting system conduction-cooled by a two-stage refrigerator without liquid cryogens. The switch connects thermally the first and the second stages (ON) to take advantage of the larger refrigeration capacity at the first stage during the beginning period. After the cryogenic temperature is reached, the switch should isolate thermally the two stages (OFF) in order to reduce the heat leak to the cold end. In this paper, a new concept for the performance index is introduced to evaluate the reduction of the cooldown time and the increase of the cooling load at the same time. In addition, the design of a gas-gap switch is discussed as a closed container of several staggered concentric tubes filled with gas, which is frozen at low temperatures for the shut-off of heat without any mechanical actuation. Some of the detailed features in the design is quantitative investigated by the gas convection model in the continuum or the rarefied gas region.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.230-231
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• 2012

This paper describes a gate driver that operates numerous semiconductor switch in the solide-state pulsed power modulator. the proposed gate driver is designed to receive both the isolated drive-power and the on/off pulse signals through the transformer. Moreover, the IGBT-switch can be quickly turned off by adding protection circuit. Therefore it protects the IGBT-switch from the arc condition that frequently occurs in high-voltage pulse application. To comprehend operating characteristic of each IGBT-switch in pulse output condition, the device consisting of a high efficiency soft-switching capacitor charger and two series stacking IGBT-switch is developed. Finally, the relability of the proposed gate driver and the device for its test are proved through PSpice simulation and experiments.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.668-676
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• 1998

A passive energy recovery snubber for high-power-factor boost rectifier, in which the main switch is described in terms of the equivalent circuits that are operational during turn-on and turn-off sequences. These equivalent circuits are analyzed so that the overshoot voltage across the main switch, the snubber current, and the turn-off transition time can be predicted analytically. The main switch combined with proposed snubber can be turned on with zero current and turned off at limited voltage stress. The high-power-factor boost rectifier with proposed snubber is implemented, and the experimental results are presented to confirm the validity of proposed snubber.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.295-297
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• 2004

A double-role double through switch with defected ground structure (DGS) is Proposed. The equivalent circuit for the proposed switch structure is derived based on equivalent circuit of newly proposed DGS unit structure. The equivalent circuit parameters of DGS unit are extracted by using the circuit analysis method The on/off operation of the proposed switch Is obtained by varying the capacitance in the ground metallic plane The experimental results show excellent insertion loss characteristic at on state and isolation characteristic at off state.

• Journal of the Korea Society of Computer and Information
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• v.22 no.6
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• pp.123-129
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• 2017

In this paper, we proposed a smart multiple-tap system which a remote user with smartphone can control multiple-taps in order to reduce standby-power consumption more conveniently when plugged-in electric appliances are turned-off. Recently, several researches of smart multiple-tap using IoT technology has reported. However, in these researches, an additional device like as a server computer is necessary, or multiple-taps could be only remotely controlled by smartphone and not directly controlled by on/off switch. The proposed smart multiple-tap system does not need any additional device only if it has a WiFi router, and it can be used for user as well as remote control using smartphone application and physically direct control using contact switches like existing multiple-taps. Our approach is to develop a smart multiple-tap device capable of WiFi communication can each serve as a server or a client, and can be operated by the hybrid switch combining the on/off contact switch and the relay switch. We implemented the prototype of the proposed system composed of the smart multiple-tap device and the smartphone application, and the test of the prototype validates the proposed system.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1026-1029
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• 1993

Inherent speed-torque performance of Switched Reluctance Motor is similar to that of series wound DC motor. Thus, the speed of the motor is extremely regulated according to load torque. For the purpose of controlling the speed and torque of SRM it is necessary to change the applied DC link voltage or the switch-ON and switch-OFF angles which control the phase current of the motor. This paper describes speed-torque characteristics of an integral horse power Switched Reluctance Motor by adjusting the switch-ON and switch-OFF angles. Speed at rated load torque can be regulated by adjusting the switching angles and the control scheme is applied to 2kW, 3 phase, 6/4 SRM.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1629-1631
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• 2003

고전압 대전류 펄스파워에 사용되는 스위치는 여러 종류가 사용되고 있는데, 커페시터에 저장된 초기의 전자 에너지를 시공적으로 압축하여 수ns ${\sim}$ 수ms의 짧은 시간안에 고출력을 발생시키기 위해서는 펄스파워 장치에 사용되는 커패시터, 인덕터, 저항, 스위치등 회로 소자들의 임피이던스가 작아야 할 필요성이 대두 된다. 따라서 Inverse Pinch Switch(IPS)는 이런 조건을 만족시킬수 있는 스위치로서 각광을 받고 있다. 본 논문에서는 전기트리거형 IPS의 금속 전극부와 절연 ceramic를 brazing하여 sealed off type의 스위치의 제작 과정과 특성을 연구 하였다.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.153-155
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• 1998

A novel soft-switching pulse-width modulated boost-type DC-DC converter topology is presented in this paper. The conventional boost switch is replaced by a switching cell that is comprised of two switch-diode pairs being linked by an inductor for zero-current switching turn-on. The diodes commutate the current that is flowing through the soft-switching inductor when the two switch turn-off. The capacitor is placed in parallel with the two switches during turn-off, thus providing zero-voltage switching turn-off. Simulation results are presented to support the theoretical considerations.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1539-1548
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• 2018

This paper introduces a new soft switched AC-DC boost converter with power factor correction (PFC). In the introduced converter, all devices are turned on and off under soft switching (SS). The main switch is turned on under zero voltage transition (ZVT) and turned off under zero current transition (ZCT). The main diode is turned on under zero voltage switching (ZVS) and turned off under zero current switching (ZCS). Meanwhile, there is not any current or voltage stress on the main devices. Besides, the auxiliary switch is turned on under ZCS and turned off under ZVS. The detailed theoretical analysis of the converter is presented, and also theoretical analysis is verified by a prototype with 100 kHz and 500 W. Also, the proposed converter has 99.8% power factor and 97.5% total efficiency at soft switching operation.