• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.69-75
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• 2009

This paper studies the aerodynamic performance that the vent mixer-new conceptual supersonic mixer-showed with its geometric characteristics. The hole is 2 mm with 2 mm's distance from the wall in case 1 and with no distance in case 2. In case 3 die hole is 1 mm. Case 1 and case 2 showed the same total pressure recovery ratio, of which the case 3 was lower than that. While cases 1-3 had the same reattachment length, the shear layer was thicker in cases 1 and 2 than in case 3. Within the recirculation zone, cases 1 and 2 had lower pressure loss and higher velocity gradient difference than case 3-they enhance mixing between air and fuel. Separation bubble which is developed by the inflow into the recirculation zone has a significant effect on the total pressure recovery ratio in the combustor. Also separation bubble influences pressure distributions and recirculation flows in the recirculation zone. Therefore, inflow rate of air into the recirculation zone mainly affects the performance of vent mixer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.2
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• pp.303-308
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• 2001

An objection of this study is to develop a high stable measuring circuits and a analytic system for radioactive pulses. The proposed system consists of a pulse detection units for neutrons and gamma-rays a programmable high voltage supply unit and a digital signal processor. The programmable high voltage supply unit designed can generate DC voltage up to 1,500 V at 5 V input and have a series voltage regulator to maintain the output voltage constantly, resulting in less than 1.63% of voltage regulation. The pulse detection parts consists of an active integrator, a pole-zero circuit, and a 3-stage amplifier of 60 dB, and its frequency bandwidth is from 37 Hz to 300 kHzAlso, pulse height distribution in accordance with pulse counts is important data in analyzing radioactive pulses. In this study, A/D convertor (12bit, 100ms) and DSP (TMS320C31-60) are used to analyze the pulse height, and the analytic system is designed to be operated in PC-base.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.644-647
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• 2001

The investigations were discussed on the radiation effects of the electrical properties to the p-type MOS capacitors, which were irradiated by cobalt-60 gamma ray sources. The characteristics of capacitance-bias voltage(C-V) and of dielectric dissipation tarter-bias voltage(D-V) on the capacitors were measured at 1 [MHz] frequency. The microscopic behaviors of spate charges in oxide and silicon-silicon dioxide(Si- $SiO_2$) interface were investigated from the experimental data. The C-V characteristics are statical and convenient for the evaluation of the steady state behavior of carriers and interface states characteristics. While, the distribution and magnitude of space charges in oxide can be found out accurately on the $V_{dp}$ in D-V curves. The density of interface states can be deduced with ease from the magnitude of D-peak at depletion state. Thus, it is also concluded that the D-V curves are more useful and easier than conventional C-V curves for analysis of the microscopic and dynamic behavior of carriers in oxide and Si- $SiO_2$interface.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.163-168
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• 2015

This paper analyzed the deviation of tunneling current for bottom gate voltage of sub-10 nm asymmetric double gate MOSFET. The asymmetric double gate MOSFET among multi gate MOSFET developed to reduce the short channel effects has the advantage to increase the facts to be able to control the channel current, compared with symmetric double gate MOSFET. The increase of off current is, however, inescapable if aymmetric double gate MOSFET has the channel length of sub-10 nm. The influence of tunneling current was investigated in this study as the portion of tunneling current for off current was calculated. The tunneling current was obtained by the WKB(Wentzel-Kramers-Brillouin) approximation and analytical potential distribution derived from Poisson equation. As a results, the tunneling current was greatly influenced by bottom gate voltage in sub-10 nm asymmetric double gate MOSFET. Especially it showed the great deviation for channel length, top and bottom gate oxide thickness, and channel thickness.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.1
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• pp.53-58
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• 2002

New nondestructive inspection (NDI) technique to detect the defect in metal was developed in which an electromagnetic field is induced in a metal by AC current flowing in the magnetic coil and the leak magnetic-flux disturbed by defects is measured using a tape-recorder head with air gap. This technique can be applied in evaluating the location and sizing of surface defects in components of the ferromagnetic body by means of the non-contacting measurement. In this paper, we have applied this technique to the evaluation of two-dimensional surface cracks in ferromagnetic metal, and also investigated the influence of the various frequencies and lift-off. Defects were detected with maximum values in the distribution of voltage and it was found that the maximum values tend to increase with the defect depth. Although the maximum values for defects are affected by the frequency and lift-off, the depth of small defects can be estimated from the linear relationship between the depth and voltage rate$(V_0/V_{ave})$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.907-909
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• 2009

In this paper, the dependence of threshold voltage on the gate oxide thickness, which it mostly influenced on short channel effects in fabrication of FinFET, has been investigated. The transport model based on three dimensional Possion's equation has been used to analyze influence on gate oxide thickness. The gate oxide thickness is the most important factor to influence on the threshold voltage in nano structure FinFET. The potential distributions of this model are compared with those of three dimensional numerical simulation to verify this model. As a result, since potential model presented in this paper is good agreement with hree dimensional numerical model, the threshold voltage characteristics have been considered according to the gate oxide thickness of FinFET.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.115-117
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• 1996

The electrical stress, which is generated by switching devices, has been affected by various kinds of factors such as surge impedance, motor capacity, surge wavefront and so forth. In this study, the surge phenomenon delivered into motor winding in switching was analyzed with actual system.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.2 no.3
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• pp.47-58
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• 1988

본 논문에서는 고광도방전등의 전기적 특성을 해석하기 위한 아아크모델을 제시하였다. 방전관내에서 반경방향의 온도분포가 포물선형태로 변화하는 것으로 가정하고 방전관의 단위체적에서의 에너지평형식을 단면적에 대해 적분함으로서 단위길이당의 에너지평형식으로 변환하였다. 이 에너지평형식과 회로방정식, 그리도 오옴의 법칙을 이용하여 아아크의 전류와 전압의 1주기에서의 변화를 계산하여 좋은 결과를 얻었다. 또한 방전관의 축온도와 이에 따른 방사에너지의 값을 계산하는 간단한 방법을 제시하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.886-887
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• 2011

본 논문에서는 농형 유도전동기의 회전자 도체 형상을 변화시켜 토크 특성을 살펴본다. 회전자의 변화에 의한 영향만을 고려하기 위해 고정자룰 간단히 모델링 하고 전압일정조건을 인가했으며 그에 해당하는 토크 식을 유도했다. 회전자 도체는 가장 기본적인 Canned 형상으로부터 시작하여 복잡한 슬롯 형상까지 도입하여 해석하였다. 해석된 결과들을 이용해 각 도체 형상에 의한 자계 분포와 함께 고찰한다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.4
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• pp.74-81
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• 1997

I정전 모-터는 일반적으로 분극전하와 전계의 상호작용을 이용한 것으로서 전계내에 축적되는 전계에너지(W=1/2 *ED)의 힘을 기계적 출력으로 도출하여 이용하는 것이다. 본 논문에서는 유한 요소법을 사용하여 단상 정전 모터의 전계와 등전위분포 및 미소한 토오크를 시뮬레이션을 통하여 구하고 해석하였다. 그 결과 이 모터는 특성상 정전, 역전이 가능하고 고전압에서 응용이 가능하므로 특수기의 서어보모터로 쓸 수 있겠고, 설비중 고압으로 인한 위험이 따르는 곳의 안전예고기, 고전압계, 위상 판별기로도 사용이 가능할 것으로 기대된다.