• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.8
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• pp.622-628
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• 2001

We developed 1- and 2-dimensional fluid model for the analysis of a capacitively coupled Ar RF(Radio Frequency) glow discharge. This discharge is in pure Ar gas at the pressure 100[mTorr], frequency 13.56[MHz] and voltage amplitude 120[V}. This model is based on the equations of continuity and electron energy conservation coupled with Poison equation. 2-dimensional model is simulated on the condition of GEC(Gaseous Electronic Conference cell). The geometry of the discharge chamber and the electrodes used in the model is cylindrically simmetric; tow cylinders for the electrodes are surrounded by the grounded chamber. It is shown that 1-dimensional model is very useful on the understanding of RF glow discharge property and of the movement of charged particles. 2-dimensional model predicts off-axis maximum structure as in the experiments and has the results in qualitatively and quantitatively good agreement with the experiments. Effects of dc self-bias voltage, guard ring and reactor geometry is discussed.

• ETRI Journal
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• v.32 no.1
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• pp.68-72
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• 2010

The coupling between the transverse and longitudinal components of the channel electron motion in NMOS devices leads to a reduction in the barrier height. Therefore, this study theoretically investigates the effects of the in-plane velocity of channel electrons on the capacitance-voltage characteristics of nano NMOS devices under inversion bias. Numerical calculation via a self-consistent solution to the coupled Schrodinger equation and Poisson equation is used in the investigation. The results demonstrate that such a coupling largely affects capacitance-voltage characteristic when the in-plane velocity of channel electrons is high. The ballistic transport ensures a high in-plane momentum. It suggests that such a coupling should be considered in the quantum capacitance-voltage modeling in ballistic transport devices.

• Survey Research
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• v.1 no.1
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• pp.125-134
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• 2000

It is very important to keep scientific principles in marketing research, Especially in sampling we have to select the scheme to avoid self-selection bias Internet index is ready-made-research service produced by analyzing the log data transferred from PcMeter installed in panelists PC with panelists profile and site data base following the scientific principles Through the index we can figure out the actual behaviour of Korean netizen surfing various web sites and understand their cybergraphics.

• Advances in Computational Design
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• v.1 no.3
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• pp.275-296
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• 2016

This article presents an adaptive directional differential evolution (ADDE) algorithm and its application in solving discrete sizing truss optimization problems. The algorithm is featured by a new self-adaptation approach and a simple directional strategy. In the adaptation approach, the mutation operator is adjusted in accordance with the change of population diversity, which can well balance between global exploration and local exploitation as well as locate the promising solutions. The directional strategy is based on the order relation between two difference solutions chosen for mutation and can bias the search direction for increasing the possibility of finding improved solutions. In addition, a new scaling factor is introduced as a vector of uniform random variables to maintain the diversity without crossover operation. Numerical results show that the optimal solutions of ADDE are as good as or better than those from some modern metaheuristics in the literature, while ADDE often uses fewer structural analyses.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.309-314
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• 1999

The magnetized helical resonator plasma etcher has been built. Electron density and temperature were measured as functions of rf source power, axial magnetic field, and pressure. The results show electron density increases as the magnetic field increases and reached $2\times1012cm^{-3}$,/TEX>. The oxide etch rate and selectivity to polysilicon were investigated as the above mentioned conditions and self-bias voltage. We can obtain the much improved oxide etch selectivity to polysilicon (60 : 1) by applying the external axial weak magnetic field in magnetized helical resonator plasma etcher.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.4
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• pp.261-266
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• 1998

In developing the high density memory device, the etching of fine pattern is becoming increasingly important. Therefore, definition of ultra fine line and space pattern and minimization of damage and contamination are essential process. Also, the high density plasma in low operating pressure is necessary. The candidates of high density plasma sources are electron cyclotron resonance plasma, helicon wave plasma, helical resonator, and inductively coupled plasma. In this study, planar type magnetized inductively coupled plasma etcher has been built. The density and temperature of Ar plasma are measured as a function of rf power, flow rate, external magnetic field, and pressure. The oxide etch rate and selectivity to polysilicon are measured as the above mentioned conditions and self-bias voltage.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.223-230
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• 1997

최근들어 그 활용도가 점점 증대되고 있는 DLU(Diamond-like Carbon) /Diamond 박막(thin film)의 합성기술을 개발하여 원자력분야에 응용하고자 시도하였다. 이를 위하여 13.56 MHz의 고주파(RF: radio-frequency)를 사용하는 플라즈마 화학증착(PECVD: Plasma Enhanced Chemical Vapor Deposition) 장치를 직접 제작하여 탄소함유(CH$_4$, $CO_2$...등) 기체로부터 기본적인 DLC 박막증착시험을 수행하였다. 실험은 진공증착기(vacuum chamber)내의 압력(pressure), 탄소함유 기체의 조성비, 그리고 바이어스전압(negative self-bias voltage)둥을 변화시키면서 수행하였다. 증착속도(deposition rate)는 증착층의 두께를 알파스템($\alpha$-step)으로 측정하여 결정하였으며, 이로부터 증착속도가 압력 및 바이어스 전압의 증가에 따라 증가함을 알 수 있었다. 또한 바이어스 전압 300V 이상에서 $CO_2$량 증가가 증착속도를 촉진시킨다는 사실도 확인하였다. 그리고 EPMA(electron probe micro-analyser) 및 Raman 스펙트럼분석을 통하여 증착층의 구조가 DLC 임을 확인하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.517-519
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• 2022

뉴럴 네트워크는 학습에 사용하는 파라미터를 문제에 맞게 최적화하여 일반화 성능을 향상시키는 것이 목적이다. 선행 연구들은 다차원의 로스 랜드스케이프(loss landscape)를 시각화하는 방법을 탐구하며, 모델의 일반화 측면에서 어떤 영향을 주는지 탐구한다. 하지만 아직까지 로스 랜드스케이프가 근본적으로 일반화 성능에 어떠한 영향을 주는지 잘 알려져 있지 않으며, 평평하거나 경사진 로스 랜드스케이프 중 어떤 형태가 일반화 성능에 더 효과적인지 여러 의견이 나뉜다. 따라서 우리는 로스 랜드스케이프가 일반화 성능과 연관 있음을 실험을 통해 파악한다. 나아가 비전문제에서 MSA(multi-head self-attention) 레이어를 기반으로 구성된 트랜스포머 구조를 사용해 작은 유도 편향(inductive bias)을 가지며 소규모 데이터 셋 체제에서의 단점을 보완한다. 결론적으로 평평한 로스 랜드스케이프가 일반화 성능에 긍정적인 영향을 끼친다는 것을 관찰한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.4
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• pp.1-8
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• 2005

Plasma researches using parallel-plate electrodes are widely used in semiconductor application such as etching and thin film deposition. Therefore, a quantitative understanding and control of plasma behavior are becoming increasingly necessary because their important applications and simulation techniques have been actively carried out in order to solve such problems above. In this paper, we developed a two-dimensional(2D) self-consistent fluid model, because 2D models can deal with real reactor geometries. The fluid model is based on particle continuity equations for taking account of an electrode system in a cylindrical geometry. An pure Ar gas was used at 500[mTorr] and radio-frequency (13.56(MHz)). Four models were simulated under the different electrode geometries which have chamber widths of 5.25, 6.0, 8.0, and 10.0[cm] and we compared their results with each other. Plasma uniformity and a do self-bias voltage were also discussed.

• Journal of the Korean Society of School Health
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• v.12 no.1
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• pp.71-84
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• 1999

This study attempts to identify the self-image of eyeglass wearers with Q-methodology. Preliminary Q-statements were collected through personal and telephone interviews and based in consultation with reference books, eyeglass wearers, an optician and an oculist. Finally, 34 Q-samples were seleted. The results were analyzed by a Q-factor with a PC QUANL Program. The self-image of eyeglass wearers were found to revolve around three types: Type 1. They feel that eyeglasses have a negative influence on image and that they uncomfortable. In addition, other people have a negative bias toward people who wear eyeglasses. As a result of these negative prejudices and inconveniences, there is a tendency to wear contact lens or have laser operations. Type 2. They feel less uncomfortable comparatively, when explained that glasses can help improve their image. When explained as a fashion accessory, negative prejudices almost disappeared. Type 3. They show a positive reaction when explained that spectacles are also used for sight protection. Howerer, they are sensitive to changes in their complexion as a result of eyeglass wear and place much importance in the design of glass frames. The significance of this study is to suggest basic data for a mediation device that improve the image of eyeglass wearers discovery and analysis of these three types.