• 전기학회논문지
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• 제56권12호
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• pp.2091-2097
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• 2007

This paper described the verification of modeling technique of underground distribution from comparison between field test and simulation. It needs more exact transient phenomenon analysis model to establish lightning protection of underground distribution line. Although, there were a lot of transient phenomenon researches, nobody could has verified the confidence of modeling from field tests in interior until now. So, simulation model verified field test is needed to analyse transient phenomenon of underground distribution system. The examination must be accomplished in many different condition before suggesting these verified analysis model. In this paper, the conditions were examined and the various data results on the different line composition was compared with the EMTP simulation, when the lightning impulse test was accomplished at underground distribution line. Also the value between field test and simulation was very closed and the method of modeling has demonstrated confidence, when the method is used to analyse domestic transient phenomenon of underground distribution.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.247-253
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• 2014

In this paper, a new two dimensional (2D) analytical modeling and simulation for a Dual Material Double Gate tunnel field effect transistor (DMDG TFET) is proposed. The Parabolic approximation technique is used to solve the 2-D Poisson equation with suitable boundary conditions and analytical expressions for surface potential and electric field are derived. This electric field distribution is further used to calculate the tunnelling generation rate and thus we numerically extract the tunnelling current. The results show a significant improvement in on-current characteristics while short channel effects are greatly reduced. Effectiveness of the proposed model has been confirmed by comparing the analytical results with the TCAD simulation results.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2000년도 춘계 학술발표회 논문집
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• pp.43-50
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• 2000

The flow field of a 1 Ton/Day entrained-flow gasifier constructed in KIER was numerical simulate in this paper. The standard $k-{\varepsilon}$ turbulence model and simple procedure was used with the Primitive-Variable methods during computation. In order to find the influence factors of the flow field which may have great effects on coal gasification process inside gasifier, difference geometry parameters at various operating conditions were studied by simulation methods. The calculation results show that the basic shape of the flow field is still parabolic even the oxygen gas is injected from the off-axis position. There exist an obvious external recirculation zone with a length less than 1.0m and a small internal recirculation region nears the inlet part. The flow field inside the new gasifier is nearly similar as that of the old 0.5T/D gasifier at same position if the design of burner remains unchanged.

• 대한전기학회논문지
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• 제38권1호
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• pp.22-28
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• 1989

This paper describes error estimate mothod for adaptive finite element analysis of two dimensional electrostatic and magnetostatic field problems. To estimate the local errors, divergence theorem is used for electrostatic field and Ampere's circuital law for magnetostatic field. To confirm the effectiveness of the proposed error estimators, adaptive finite element computations are performed using the proposed error estimators. The rates of convergence of global errors are comparable with those of existing adaptive finite element schemes which make use of field continuity conditions between element boundaries. This algorithm of error estimate can be easily implemented because of its simplicity. Especially, when the value of charge in electrostatic field and the value of current in magnetostatic field are to be figured out, this method is considerded to be preferable to other approaches.

• 대한전기학회논문지
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• 제38권6호
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• pp.401-415
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• 1989

A simple but accurate analytical model for the lateral channel electric field in gate-offset structured Lightly Doped Drain MOSFET has been developed. Our model assumes Gaussian doping profile, rather than simple uniform doping, for the lightly doped region and our model can be applied to LDD structures where the junction depth of LDD is not identical to the heavily doped drain. The validity of our model has been proved by comparing our analytical results with two dimensional device simulations. Due to its simplicity, our model gives a better understanding of the mechanisms involved in reducing the electric field in the LDD MOSFET. The model shows clearly the dependencies of the lateral channel electric field on the drain and gate bias conditions and process, design parameters. Advantages of our analytical model over costly 2-D device simulations is to identify the effects of various parameters, such as oxide thickness, junction depth, gate/drain bias, the length and doping concentration of the lightly doped region, on the peak electric field that causes hot-electron pohenomena, individually. Our model can also find the optimum doping concentration of LDD which minimizes the peak electric field and hot-electron effects.

• 대한산업공학회지
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• 제23권3호
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• pp.533-544
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• 1997

Among numerous factors that have an effect on visual field, the effects of background condition on the size of the visual field were investigated to obtain more practical visual field that can be readily applicable to industrial settings. A visual experiment was conducted, in which the subject was instructed to search a target with distinct orientations. Size contrast, meridian, nontarget density, and subject's gender showed a significant effect on the size of the visual field at $\alpha=0.01$. The size of the visual field was linearly proportional to size contrast, and inversely proportional to density. Female's visual fields were found to be significantly larger than male subjects', The size of the visual field on horizontal axis was larger than that on vertical axis, and the size of the head & eye field on right meridian was also larger than that on left meridian. The shape was found to be horizontally oriented oval and statistically asymmetric with respect to horizontal and vertical axes. The regression equations to predict the visual fields on the given background condition were suggested. The visual fields suggested in this study would be valuable to the design of visual displays and the panel layout of various displays and controls.

• 한국결정성장학회지
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• 제13권2호
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• pp.93-97
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• 2003

FALC(Field-Aided Lateral Crystallization) 공정에서 요구되는 a-Si의 결정화는 인가한 전계(electric field)의 세기와 방향에 의존한다. 본 연구에서는 유한요소법을 적용하여 실제 패턴을 간단하게 모델링한 형상에 각 물질의 전도도를 대입하고, 전안을 가해 그 결과로 발생하는 전계의 분포를 계산하였다. 전계는 (-)극 주위에서 전극의 양쪽 모서리 부근이 가운데 부분보다 더 높게 나타났고 그 방향은 전극과 50~$60^{\circ}$를 이루는 대각선 방향이었다. 또한 예상한대로 크기가 작은 패턴이 큰 패턴보다 더 큰 전계 값을 가지는 것으로 나타났다.

• 한국음향학회지
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• 제35권1호
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• pp.35-41
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• 2016

본 논문에서는 상관함수와 최소자승 기법에 기반하여 단일 음원의 위치가 원거리 혹은 근거리 모두 가능한 경우, 이에 상관없이 닫힌 형태로 위치를 추정하는 기법을 제안한다. 최근 균일 환영 배열에서 상호상관함수를 이용하여 원거리 단일 음원의 위치를 2차원으로 추정하는 기법이 제안되었으며, 이를 확장하여 근거리 단일 음원의 위치를 3차원으로 추정하는 기법이 제안되었다. 그러나 기존 기법은 음원의 위치가 원거리, 혹은 근거리로 제한된 상황만 다루고 있다. 반면 제안 기법은 먼저 원거리 음원으로 가정하여 거리 독립적으로 방위와 고각을 구하고 이후 거리 추정에서 원거리와 근거리 음원을 구분하여 혼합 환경에 적용가능하다. 시뮬레이션에서는 두 가지 경우 모두에 대해 실험하여 제안 기법의 타당성을 검증하였다.

• 경영과정보연구
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• 제18권
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• pp.163-182
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• 2006

In social welfare arena field practicum has been an essential instrument and method for social work students to get socialized to the social work professional. However, to whom involve in the actual field practicum-universities(or colleges), institutes - have some difficulties. On the base of community welfare is a clinical approach in this times. To strengthen community welfare policy, the beginning of community welfare committee is such a good opportunity to tackle the problems of the field practicum. This study suggest that the problem of the field training are 1) a guidance of an individual social work institute, 2) the lack of social work institute, 3) the absence of the trainee's sense of values, 4) the bad conditions of the field practicum for social work students in undergraduate courses at the university(or college), and 5) the lack of professionalism for supervisors. This study makes the following social work suggestions to vitalize field practicum in community welfare. It is more likely important to 1) make the law of the field practicum for undergraduate social work courses, 2) make the coordinated programs of the field practicum for undergraduate social work course in community welfare, 3) enlarge the opportunity that a field specialist take further education, 4) support and carry of supervisor reeducation, 5) make the program development of trainee's personal experiences in social work values, and 6) social work professors make a practice in the social work field.

• 한국균학회지
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• 제14권2호
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• pp.109-119
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• 1986

인삼(人蔘)의 토양병해(土壤病害) 방제에 효율성을 높이고, 증산에 기여 할 수 있는 기초자료를 얻고자 우리나라 주요 인삼 재배지인 금산(錦,山), 풍기(豊基), 괴산(槐山)의 3년근 재작지(再作地)와 초작지(初作地) 토양을 선정하여 이들 토양의 물리화학적 성질과 토양 내 분포한 미생물들 사이에 상호 관련성을 조사하였다. Fusarium속의 월별 분포는 초작지 및 재작지 모두 가을철에 증가하였고, 괴산(槐山)을 제외한 풍기(豊基)와 금산(錦山) 재작지가 이들 동일지역의 초작지 보다 $1.9{\sim}2.6$배 더 많이 분포하였으며, Fusarium속/전 진균의 비도 금산(錦山), 풍기(豊基)의 재작지에서 증가하였다. 전 진균은 대체로 6,7월에 증가되었으나 기온변화에 따른 민감한 증감없이 고루 분포되었고 표층부에 많이 분포하였다. 유기물과 인산의 함량은 초작지에서 많았고, 인산/유기물량의 비, Mg/유기물량의 비, Mg함량 등은 재작지에서 많은 경향이 있다. 토양의 pH는 $4.5{\sim}5.7$로 모두가 약 산성 토양이었다. 토양의 수분량은 겨울철에 증가 되었으며 생육기간에 수분량은 큰 차이가 없고, 평균적으로 초작지는 24.6%, 재작지는 19.5%였다. 토양의 온도는 $7{\sim}8$월이 높았고, $1{\sim}2$월은 가장 낮았다.