• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.1166-1169
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• 2005

This paper describes a new transient voltage suppressor(TVS) with a low insertion loss and a high cut-off frequency to protect antenna circuit from transient voltages. Conventional protection devices have some problems such as a low frequency bandwidth and a high insertion loss. In order to improve these limitations, a coaxal type TVS, which consists of a gas tube is developed. The performance of the proposed transient voltage suppressor is tested by using a combination surge generator specified in IEC 61000-4-5 standard and by using a network analyzer of 40 MHz ${\sim}$ 5 GHz bandwidth. From the experimental results, it is confirmed that the proposed TVS has an enough protection performance in a low insertion loss and a high cut-off frequency.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.120-125
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• 2006

In contrast to the conventional trigatron switch in which the currents are constricted by the z-pinch mechanical the new switch operates in an inverse pinch geometry formed by a pair of spiral electrodes in a sealed-off type. Inverse pinch switch greatly reduces hot spot formations and protects the electrode surfaces. The switch can be initiated with an electrical trigger electrode. Advantages of the new switch over the conventional switches are longer useful life, high current capability and lower inductance due to the dispersed and moving current sheet. These improved characteristics may make the inverse pinch switch suitable for pulse power systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.538-545
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• 1995

The heat transfer model of ondol heating system is derived in the linear form. The step responses of On-Off controller, PID controller and Position type fuzzy controllers are compared in the sense of several aspects : variation of temperature feedback variable, variation of supplied heat quantity by the boiler, variation of flow rate, variation of thickness of the base, variation of the outdoor temperature.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1259-1260
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• 2006

Intensive technological research on the Dry-bag CIP equipment was carried out to improve the dimensional accuracy and the productivity. The rubber mold design technology using FEM simulation during pressing was introduced, in order to achieve higher dimensional preciseness, and criteria for the selection of the In-line type or Off-line type, were established based on the powder flowability index proposed by Carr. Based on these research results, high productivity Off-line Dry-bag CIP equipment, which can realize good dimensional accuracy with high productivity, was developed even for non-granulated powders with poor packing density.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1760-1762
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• 2000

본 논문은 기존의 $Si_{3}N_4$, SiN 물질 대신 Pt를 사용해 HF 용액속에서 다공질 실리콘과 전극을 동시에 형성하는 기술을 개발하였다. Pt를 실리콘 웨이퍼 위에 직접 증착한 후 습식 에칭과 Lift-off 공정을 사용하여 Pt를 패터닝하였다. 습식 에칭은 에칭용액의 온도를 일정하게 유지하는 것이 중요하며, 증착한 Pt 박막이 BOE 에칭에 견디고, Lift-off 공정이 가능하기 위해서는 기판온도를 l100$^{\circ}C$ 이하로 해야한다. Pt를 사용하면 기존의 mask에서 발생하는 가장자리 부분에서의 전류 집중이 방지되기 때문에 다공질 실리콘이 일정한 깊이로 형성되고, Al대신 오믹 전극으로 사용할 수 있다. 현재 Pt를 mask와 전극으로 이용한 P-I-N UV detector, 광 바이오센서, 습도센서 제작등에 응용 연구가 진행되고 있다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.53-58
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• 1998

A buried channel poly-Si TFT (BCTFT) for application of high performance integrated circuits has been proposed and fabricated. BCTFT has unique features, such as the moderately-doped buried channel and counter-doped body region for conductivity modulation, and the fourth terminal entitled back bias for preventing kink effect. The n-type and p-type BCTFT exhibits superior performance to conventional poly-Si TFT in ON-current and field effect mobility due to moderate doping at the buried channel. The OFF-state leakage current is not increased because the carrier drift is suppressed by the p-n junction depletion between the moderately-doped buried channel and the counter-doped body region.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.6
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• pp.1282-1289
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• 1988

It has recently shown that a solenoid valve can be utilized in a hydraulic position-control system by discontinuous control methods. The objective of this study is to investigate the effects of solenoid valves on the response characteristics of a hydraulic position-control system by applying two kinds of discontinuous control methods i.e., Simple On-Off(SOF) and Pulsating On-Off(POF) controls. Three types of solenoid valves i.e., low-frequency, closed-center type(LF/C), low-frequency, tandem-center type(LF/T) were used in this study. Effects of loading conditions and control parameters on the response characteristics were experimentally examined and compared each other. Pressure transients within the actuator were also studied.

• Proceedings of the KIEE Conference
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• summer
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• pp.1226-1228
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• 2004

A novel lossless passive snubber is proposed for soft switching the boost type converters. The proposed snubber does not use any auxiliary switches. but uses two identical snubber capacitors which are charged in parallel at turn off of the main switch and discharged in series at turn on automatically, and the discharged energy is recovered effectively (more than $95[\%]$ recovery) into the output capacitor. Thus, the snubber provides zero voltage switching for the converter main switch, reducing both the turn off losses and the electromagnetic interference(EMI) noise, whitch improves the converter performance. The experimental results of a 20[kHz] 600[W] DC-DC boost converter and a single-phase AC-DC boost rectifier with the new snubber are presented.

• Journal of Pharmaceutical Investigation
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• v.32 no.1
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• pp.35-40
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• 2002

We prepared a novel dosage form, peel-off type soft hydrogel using poly(vinyl alcohol), and evaluated the effect of skin penetration enhancer on the indomethacin release from soft hydrogel by in vitro permeation and in vivo absorption test. In this study, we used four enhancers-urea, dimethyl urea, 1,1,3,3-tetramethyl urea, and pirotiodecane (1-[2(decylthio)ethyl]azacyclopentane-2-one, $HPE-101^{circledR}$). In addition, we evaluated the primary skin irritation test of soft hydrogel using rabbit. From these results, we could find the pirotiodecane was a prominent enhancer, and soft hydrogel seemed to be safe and have no irritancy.

• Journal of Power Electronics
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• v.11 no.3
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• pp.285-293
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• 2011

This paper proposes two SRM driving systems using a variable dc-link voltage controlled by a single-phase inverter. Two SRM converter topologies of a half bridge type and a full bridge type are proposed according to the power circuits of an inverter. The phase current can be controlled by means of a PWM controller at the inverter, and the turn-on/off angle at the phase switches can be controlled by a position sensor at the converter in the drive system. The inverter acts as a peak-current limiter if the transient current exceeds its maximum value. SRMs using the proposed topologies maintain high efficiency due to energy regeneration after the turn-off of power switches. The operational modes of the proposed topologies are verified by simulation and experimental results.