• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.250-252
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• 2004

The aim of this paper is to provide a guide to those methods of train detection which are available, or are likely to become available, to the designer of train control or other relevant systems. In broad terms, train detection may be defined as the process of generating information which describes the location and movement of trains. Train detection information is difficult to define in isolation. Consider, for example, the train detection information required in a modern train control system. This may vary considerably : in a future high performance train control system, it might be necessary to know the precise position, direction of movement, speed, and possibly even the acceleration or braking, of all trains in the control area : in a less demanding application, it might be sufficient to know only the location of trains in terms of the occupation of sections of track.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.422-425
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• 1997

This paper describes a resonant fly-back converter for high-voltage de distribution system. The proposed converter operates to change high-voltage de into low-voltage de with isolation and large converting ratio. The converter has a thyristor switch with an LC resonant circuit for commutation in the primary side of the gap transformer. The operation of the proposed system was verified through computer simulations and hardware scaled-model tests. The proposed system can be implemented with commercially available components and proven technologies.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.589-592
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• 2002

A CMOS power amplifier for IMT-2000 is designed with 0.25-${\mu}m$ CMOS technology. This amplifier circuits consist of two cascode stages. Used cascode structure has good reverse isolation. These amplifier circuits consist of two stages which are driver stage and power amplification stage. The designed power amplifier is simulated with ADS using 0.25-${\mu}m$ CMOS library at 3.3 V power supply. Simulation results indicate that the amplifier has a PAE of 39 % and power gain of 24 dBm at 1.95 GHz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1969-1971
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• 2002

This paper presents the design and performance of low pull-in voltage MEMS switches for commercial cellular/PCS applications. The switches have all-metal (3 ${\mu}m$ thick Au) movable plates over CPW(Coplanar Waveguide) transmission line. The stress gradient in a movable plate is considered in mechanical design to obtain an accurate pull-in voltage. Series metal-to-metal contact switches are fabricated and evaluated. Those switches exhibit the low loss(<0.2 dB @1.9 GHz) with good isolation(55 dB @1.9 GHz).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.225-227
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• 2002

In this paper, novel concept of a photovoltaic(PV) power generation system adding the function of active filter(AF) is proposed. Even PV power generation system can be treated to a harmonics source for the power distribution system, it is necessary that the function of AF system in grid connected PV power generation system. Active Filters intended for harmonic solutions are expending their functions from harmonic compensation of nonlinear loads into harmonic isolation between utilities and consumer, and harmonic damping throughout power distribution system. So, the PV system combined the function of AF system can be usefully applied in power distribution system. Here, the control strategy of PV-AF system is introduced.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.467-469
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier, four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.227-230
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• 2001

This paper deals with a bidirectional ac-dc converter used in ups system application. We propose a Voltage-Source-Charge-Pump-Power-Factor-Correction(VS-CPPFC) ac-dc converters. First of all, we propose a charge pump power-factor-correction converter. Secondly, we derive and analyse a unity power factor condition. The proposed topology is based on a half-bridge for the primary and a current-fed push pull for the secondary side of a high frequency isolation transformer. The advantage of bidirectional flow of power achieved by using the same power components is that the circuit is simple and efficient. And the galvanically isolated topology is specially attractive in battery charge/discharge circuits in ups system. We design equivalent model for the steady-state circuit and analyse operation waveforms for each mode. We show that the proposed model can be applied to ups system by simulation processes.

• 전자공학회논문지A
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• 제28A권9호
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• pp.743-751
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• 1991

This paper presents the 1.5\ulcorner PSA bipolar device which establishes the performance improvement such as the reduction of emitter resistance and substrate junction capacitance. To achieve the above electrical characteristics, RTA process and trench isolation technology were adapted. The emitter resistance and substrate capacitance of npn transistor having 1.5$[\times}6{\mu}m^{2}$emitter area was measured with 63$\Omega$and 28fF, respectively. The minimum propagation delay time shows 121ps at 0.7mW from the measurement of 31 stage ring oscillator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2458-2460
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• 1998

To drive motor or heating machine, it needs the electric power system like the apparatus of inverter. This electric power system obviously comprises power switching devices and drivers to run them. And this system has the topology comprised one/many arm(s), - each arm has high side switching device and low side switching device. Transformer, photocoupler, and HVIC having functions of isolation and level shift which are important thing to drive high side switching device are used as component of drivers in conventional apparatus. Piezoelectric transformers are proposed in this paper, and applied to drive high side swiching device. Through experiments, the possiblities of driving high side switching device are presented and the problems are mooted concurrently. But, we also consider a counterplan for solving the mooted trouble issues.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.2213-2215
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• 2000

In this paper we implemented a novel re-entrant mode microstrip directional coupler for realizing the high directivity characteristic using finite element (FE) analysis. In microstrip configuration, the high directivity can be reached by matching the even- and odd-mode effective phase velocities. Through the values of capacitance obtained from 2-dimensional finite element(FE) analysis, the phase velocities for each mode and the design parameter were extracted for the proposed coupled-line configuration. Based on the extracted design parameter with phase matching condition we designed and fabricated 30dB directional coupler at 850MHz. Experimental results show good performance with excellent isolation.