• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.241-243
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• 2007

Two-stage charge equalization scheme for HEV lithium-ion battery string is proposed with the optimal power rating design rule in this paper, where in the first stage the over charged energy of higher voltage cells is drawn out to the single common output capacitor and then, that discharged energy is recovered into the overall battery stack in the second stage. To achieve charge equalization of sort, the conventional flyback DC/DC converters of low power and minimized size are employed. The industrial sample employing both the proposed two-stage cell balancing scheme and the optimal power rating design rule shows good cell balancing performance with reduced size as well as low voltage stresses of the electronic devices.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.501-506
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• 2013

A hold-up time compensation circuit is proposed to get high efficiency of the front-end phase-shifted full bridge DC/DC converter. The proposed circuit can make the phase-shifted full bridge front-end DC/DC converter built with 0.5 duty ratio so that the conduction loss of the primary side and voltage stress across rectifier in the secondary side are reduced and the higher efficiency can be obtained. Furthermore, the requirement of an output filter significantly can diminish due to the perfect filtered waveform. A 12V/100A prototype has been made and experimental results are given to verify the theoretic analysis and detailed features.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1517-1518
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• 2006

This paper describes the design and fabrication of a partial discharge(PD) analyzer to evaluate insulation performance for low-voltage electrical and electronic devices. The analyzer consists of an adjustable AC power supply, a coupling network, an amplifier, a shielding encloser, a sample-hold (S/H) circuit and a data acquisition (DAQ) board. The analyzer holds the height of PD pulse for $10{\mu}s$ by the S/H circuit, and this makes possible to measure PD pulses having fast rise and short duration by a low speed analog-to-digital (A/D) converter. The data are transmitted to the personal computer through the DAQ board, and the designed analysis program calculate apparent charges, discharge inception and extinction voltages.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.690-692
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• 2003

The single phase switched reluctance motor has been studied and developed actively in the various applications with several kinds and forms because of the developments of the design technique by using the computer and of the driving technique power electronic technology, which has the merits of a simple and robust structure, and first of all reducing the number of the switching devices in comparison with poly phase switched reluctance motor. And also, the studies are making progess to substitute the switched reluctance motor for single phase induction motor. In the previous studies, the single phase switched reluctance motor for the drive of blower is designed with the design theory of the conventional rotating electric machine and poly phase switched reluctance motor. In this paper, we intend to select the optimal pole arc and pole pitch ratio by the FEM analysis, because the pole arc and pole pitch are very important factor to determine the characteristics of switched reluctance motor.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2630-2632
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• 2003

본 연구는 철도 선로변에 설치되는 LDTS(Local Data Transmission System)와 EIS(Electronic Interlocking System) 사이의 인터페이스를 위한 정보전송 프로토콜에 대한 성능검증 시뮬레이션을 위한 것으로, LDTS와 EIS사이의 링크사양, 전송 메시지 정보 및 형식, 장치간 전송 프로토콜 기준 등을 분석하여 파라미터들을 추출한 후, 이들을 ARQ, FEC, HARQ 방식들에 적용하여 처리율(Throughput) 및 여러 설계변수들에 대한 시뮬레이션 결과를 비교하였다. 시뮬레이션 프로그램은 Matlab과 Matlab GUI 툴을 이용하여 작성하여 사용자가 손쉽게 시뮬레이션 파라미터들을 조정할 수 있도록 하였고, Matlab 프로그램 완성후에는 이를 Stand-alone C++ 프로그램으로 코드변환하여 Matlab이 설치되지 않은 컴퓨터에서도 프로그램 사용이 가능하도록 하였다.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.9-11
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• 1993

This paper decribed the development of Thermal Imaging Oservation System(TIOS) using the serial-parallel scan method. The detectors scan five lines at a time. These are put into serial order by electronic scan converter. Digital memory and high speed multiplexer are used for the serial conversion instead of charge coupled devices. As a result, thermal imaging system be presented with exellent performance which MRTD value is less than $0.5^{\circ}K$ at 7.5 cycles/mm.

• Journal of Sensor Science and Technology
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• v.19 no.4
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• pp.313-319
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• 2010

Vibration energy harvesting is an attractive technique for potential powering of low power devices such as wireless sensors and portable electronic applications. Most energy generator developed to date are single vibration frequency based, and while some efforts have been made to broaden the frequency range of energy harvester. In this work, The effect of energy harvesting were investigated at various vibration frequencies, vibration beams, vibration point and test masses. The maximum output voltage of the bimorph piezoelectric cantilever was shifted according to vibration point. Vibration frequency with maximum output voltage decreased with the increasing length of vibration beam and increasing test mass. The sample with vibration beam length 0.5 L generated a peak output voltage of 32 $V_{rms}$ and shows a 45 % increase in voltage output in comparison to the corresponding original bimorph. It was found that a piezoelectric bimorph has a possibility to be as the energy harvesting cantilever, which is successfully tuned over a vibration frequency range to enable a maximum harvesting energy.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.372-373
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• 2006

Modern business trends call for miniaturization of electronic systems. One of the major impedances in this miniaturization is the conductive and inductive components in chips and circuit boards. Direct Write Technology can write these soft magnetic materials, thus allowing for further miniaturization of inductor devices. Another obstacle in electronics fabrication is the size limitations of thick screen-printing and the material limitations in ink jet printing. Direct Write Technologies address both of these limitations by providing feature sizes less than 20 microns with a wide range of materials possibilities. A discussion of the application of these nano-particulate materials by Direct Write Technologies will be presented.

• Journal of Satellite, Information and Communications
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• v.8 no.2
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• pp.44-49
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• 2013

LED communication is a wireless communication technology to transmit information using visible light coming out from the LED(Light Emitting Diode). It is a technique that can overcome RF(Radio Frequency) communication problems that are frequency allocations, human body hazards, security vulnerabilities, and interference between electronic devices. As a technique that can be used as lighting and communications with using LED, LED communication is suitable for ubiquitous environment. This paper introduces the process of data transmission algorithm for LED communication systems algorithm using LED, PD(Photodiode), and MCU(Micro Controller Unit).

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.335-339
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• 2001

The recent advancements in power electronic switching devices have enabled high frequency switching operation and have improved the performance of pulse-width modulated (PWM) inverters for driving induction motors. But, the insulation failures of stator winding have attracted much concern due to high dv/dt of IGBT PWM inverter. In this paper, the test results for evaluation on the stator winding insulation of low-voltage induction motors for IGBT PWM inverter applications are presented. The insulation characteristics are analyzed with partial discharge and dissipation factor tests. Also, insulation breakdown tests by switching pulse voltage are performed. An effective insulation technique to enhance the insulation strength is suggested from the test results.