• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.113-115
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• 2006

일반적으로 3상 BLDC 전동기 구동을 하기 위해서는 6-스위치 인버터와 회전속도를 제어하기 위해서는 회전속도와 회전자 위치에 대한 정보를 필요로 한다. 본 논문에서는 3상 BLDC 전동기 구동을 위한 방법으로서 4-스위치 인버터와 회전자 위치를 간접적으로 검출하는 센서리스 구동방식을 제안하였다. 또한 4-스위치 구동에 대한 문제점을 개선하기 위하여 Voltage Doubler를 이용함으로써 기존 방법에 비해 전체 구동 시스템의 비용과 크기를 줄이는 효과를 얻을 수 있고 BLDC 전동기 성능을 향상시킬 수 있다.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.364-368
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• 1999

This paper suggests switching regulator technique to overcome the drawback of conventional variable linear power supply. Switching regulator technique can eliminate the extremely lossy operation and reduce the size and weight of variable linear power supply and provide nearly constant output power over the majority of output voltage range. The topology of variable switched mode power supply is employed active clamp forward converter with a current doubler rectifier and by using control of variable-frequency together with control of fixed-frequency, output voltage can be controled. Equivalent circuits pertinent to each operational mode of converter are derived, and an experimental 20V, 50A converter was designed and built. The converter operates from an output voltage of zero to 25 V, under 100 kHz switching frequency.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.91-93
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• 2005

The purpose of this study is to evaluate effects of stiffener configuration welded to the plate on the fatigue strength. Nominal stress and hot spot stress for the stiffened plate under pure bending condition were evaluated using FEA and experiment and fatigue test for each specimen was performed. For S and SD type, the fatigue strength increase with a decrease in the nominal stress and hot spot stress. D type with doubler plate was found to have the lowest value of nominal and hot spot stress for a given condition. However its fatigue strength was smaller than the others.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2572-2573
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• 2002

RF용 칩 설계에 있어서, Transponder에서 사용되는 칩 전원은 Tranceiver로부터 방사되는 RF Power를 고효율 쇼트키 다이오드을 통하여 정류하여 칩 내부에 캐패시터에 저장하여 내부회로의 동작시 충분한 전류를 제공하게된다. 이 분야의 연구는 칩 정류 효율 향상이라는 목표로 고효율 다이오드개발 및 임피던스 매칭방법과 고효율의 안테나 개발과 더불어 활발한 연구가 계속되어져 왔다. 본 논문에서는 Transponder용 전압을 제공해주는 쇼트키다이오드 더블러(Doubler)의 내부노드에 모듈레이션(Modulation) 트랜지스터 및 Transponder로서의 입력버퍼를 설계함에 있어서, 입력버퍼의 입력으로서 안테나로부터 1차 정류된 전압을 사용할 수 있는 방안을 제시한다. 또한 이를 적용하여 개발된 RF ID(Identification Device)칩의 주파수에 따른 특성 및 결과를 고찰토록 한다.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2256-2258
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• 1999

This paper describes preliminary discussions on spatial distribution of NO density, which is mostly contained in simulated NOx exhaust, between a wire-cylinder geometry discharge gaps by using Laser Induced Fluorescence(LIF) Spectroscopy, Spatial distribution of NO density will be measured with varying NO concentrations from 166 to 644 [ppm] and diameters of central electrode from 6 to 10mm. Pulsed Nd:YAG laser. Optical Parametric Oscillator(OPO), and Frequency Doubler are used to excite NO molecules to their excited state.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1006-1007
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• 2006

An active-clamp current-fed push-pull converter for the step-up application is proposed. The proposed converter is composed of active-clamp circuits and a voltage doubler rectifier. Thus, the voltage stress of the main switches is reduced and the output diodes are clamped to output voltage. Moreover, the output diodes can achieve zero current switching (ZCS) by the series resonance between resonant capacitors and leakage inductances. The prototype is designed for 350V/1.5kW with input voltage range $30{\sim}60V$. The theoretical analysis and experimental results are presented.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.239-239
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• 2013

The peak klystron power for the PAL (Pohang Accelerator Laboratory) XFEL (X-ray Free Electron Laser) is up to 80 MW which is higher than that of PLS-II LINAC. To prevent the RF breakdown such a high power operation, some of RF components need to be redesigned to reduce the surface electric field gradient to be less than the breakdown gradient at the vacuum-metal surface. For instances, the redesign of the Stanford Linear Accelerator Energy Doubler (SLED) system, the directional coupler and 3dB power splitter using the finite-difference time-domain (FDTD) simulation will be presented.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.72-76
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• 2003

In this paper, active frequency doubler with broadband characteristics and unconditional stability from 6GHz to 12GHz was designed and fabricated using PHEMT. The designed frequency multiplier has a bias point near pinch-off and a proposed RC circuit between bias line and input matching network for the improvement of stability. With 0dBm input power, second harmonic of 1.7dBm at 12GHz, - 27.5dBc suppression of 6GHz fundamental, -18dBc suppression of 18GHz 3rd harmonic and the output bandwidth of 1.8GHz have been measured.

• Journal of the Semiconductor & Display Technology
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• v.14 no.4
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• pp.88-91
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• 2015

In this paper, we have designed and fabricated a BPF (Band Pass Filter) for 5.8GHz Microwave Wireless Power Transmission. We $used{\lambda}g/2$ open-circuited stubs in addition to T-shaped transmission lines for the BPF. This BPF removes harmonics caused by diodes of RF-DC converter, and thus the RF-DC converter converts more RF power to the DC. The performance of the BPF was measured and shown through direct comparison of voltages converted by the doubler as a RF-DC Converter with and without the BPF.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.8
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• pp.551-556
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• 2000

A zero-voltage-switching(ZVS) programmable power supply employing the ZVS active clamp forward converter is suggested. Through the analysis on operation region of the supply, the constant power region and the maximum current limit region are clearly identified. Furthermore, the duty ratio range corresponding to the variation range of the output voltages and the control scheme at the minimum duty ration region are presented. Finally, in order to vefity the validity of the operation for the proposed power supply, experimental evaluation results obtained on an 1kW prototype power supply for the 198~242VAC input voltage range(220VAC$\pm$10%), the 0~25V output voltage range, and the 100kHz switching frequency are presented.