• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.67-70
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• 1991

When analyzing field or optimizing the shape of electrode in three dimensional space by using the surface charge method, we need to divide finely the surface of electrode into surface element like triangle or rectangle. In this case, there exist any variables in field analysis or field optimization. In particular, smoothness on the surface of optimized shape is not good. Recently, A paper is published where introducing NURB curve to field analysis and field optimization about two dimensional space model and axial symmetric three dimensional space model results in reduced variables, enhenced accuracy and improved smoothness. NURB curve has some useful properties like continuity, controllability and locality. Therefore in this paper, in order to improve the demerits of the established optimization method for three dimensional space models, the NURB surface that has same properties in common with NURB curve is used to analyze and optimize simple model.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.273-275
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• 2008

본 논문에서는 하이브리드자동차(hybrid vehicle)의 고전원 전기장치 및 전기배선 충전부의 인체 접촉에 의한 감전사고의 예방을 위한 전기적 연속성의 측정방법에 대하여 논하였다. 인체 감전 보호를 위한 기본 대책으로 충전부의 기본절연, 충전부 접근에 대한 보호(배리어, 인클로져 등)가 있다. 하이브리드자동차의 전기적 연속성과 관련된 시험방법은 UNECE, ISO, Japan Attachment 등에서 언급하고 있다. 이들 기준에서 전기적 연속성은 $0.1{\Omega}$ 이하를 유지하도록 하고 있다. 본 연구에서는 하이브리드자동차의 전기적 연속성 측정 방법에 있어 외국의 기준과 규격의 내용을 검토하고 전기적 연속성 측정방법을 제시하고자 한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.361-364
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• 2008

This paper deals with assessment of electrical safety for grounding system of buildings by investigation on the spot at construction site. The investigation was carried out for grounding method, grounding type, shape of grounding electrode, grounding for lightning protection system, continuity of steelwork in reinforced concrete structure and so on. The investigation on the spot was performed by researcher, engineer with over fifteen years of industry experience all over the country. As a result of investigation on the spot to 13 buildings, common grounding method was dominant. A new grounding system based on international standards includes unity grounding system, structure grounding utilizing steel reinforced concrete, equipotential bonding. use of surge protective device.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1253-1255
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• 1993

Double Injection(DI) switching devices consist of p+ and n+ contact separated by a nearly intrinsic semiconductor region containing deep trap. The FEM is chosen as a simulation method for DI switching device, because of the advantage in local mesh refinement and computer memory comparing with other methods. And Scharfetter-Gummel(S-G) scheme is applied, with which an accurate-seven point Gaussian Quadrature rule is combined. The existance of deed trap requires the modification of conventional equation set. So recombination rate equation is modified and a new equation is included in the equation set which conventionally consists of Poisson equation and current continuity equations.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.112-114
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• 1996

In this paper a simple mesh refinement technique for finite element method is proposed using error estimation only on the material boundaries. The boundary errors are estimated by the continuity conditions of normal B field and tangential B field. From the error estimation fine meshes are accomplished on the boundary and propagate to the near region by Delanunay mesh tessellation. This adaptive mesh refinement technique is applied to the force calculation of magnetic clutch composed by several material regions and makes good convergence.

• Korean Journal of Materials Research
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• v.18 no.9
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• pp.470-474
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• 2008

Composites of gadolinium-doped ceria/magnesia(CGO/MgO) were synthesized and characterized for the electrolytes of intermediate temperature solid oxide fuel cells. XRD and SEM results revealed that composite electrolytes consisted of their own phases after sintering at $1400^{\circ}C$ without noticeable solid solution of Mg into CGO. As the MgO content increased, the total electrical conductivity decreased, which might be attributed to the decrease of grain boundary conductivity, possibly due to the lowering of the continuity of the CGO grains and blocking effects of the insulating MgO phase. The space charge effect may not be a significant factor to affect the electrical conductivity of the CGO/MgO composites.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.101-103
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• 1999

This paper presents an analysis of 2-dimensional(2-D) multi-regions problem using boundary integral equation method(BIEM). When compared with finite element method(FEM), there are only a few unknown variables in BIEM because it implements numerical analysis only for the surface or boundary of a model. As a result, a lot of computational memory and time can be saved. Procedure to analyze 2-D multi-regions problem using potentials and its derivatives in a boundary as unknown variables, first, numerical analysis is performed for each of subregions. And then interface continuity condition is applied to the interface between them and Gauss Quadrature Formula are adopted to solve singular integral in a boundary in this paper.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.167-170
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• 2001

A three dimensional adaptive finite element analysis algorithm is developed. In the method, the edge elements are used for field analysis, and the local error. In each element is estimated from the fact that the magnetic field should satisfy. The continuity condition at the interface of the two adjacent elements. Based on the estimated error, the elements which are considered to have big error are divided into several elements using the bisection method. The effectiveness of the developed algorithm is proved through numerical examples.

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.107-111
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• 2015

Our work is based on the development of a numerical model to develop a methodology for predicting the aging and breakdown in insulation due to the dynamics of space charge packets. The model of bipolar charge transports is proposed to simulate space charge dynamic for high DC voltage in law-density polyethylene (LDPE), taking into account the trapping and detrapping of recombination phenomena, this model has been developed and experimentally validation. Theoretical formulation of the physical problem is based on the Poisson, the continuity and the transport equations as well as on the appropriate models for injection. Numerical results provide temporal and local distributions of the electric field, the space charge density for the different kinds of charges, conduction and displacement current densities, and the external current.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.6
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• pp.470-476
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• 1989

In order to develop a mathematical model which can predict the operating voltage and current of a discharge lamp, the properties and the physical phenomena of a low pressure gas discharge are investigated. Fluorescent lamp which uses a low pressure mercury-argon gas discharge is used in the model development. In a low pressure mercur-argon gas discharge, the continuity equation for each excited atom and electron, and the electron energy balance equation can predict the physical quantities of discharge. By coupling these equations and the circuit equation, the electrical characteristics of the discharge lamp can be predicted. To verify the validity of the suggested model, we calculated the voltage and current of a fluorescent lamp operating with inductor ballast for source frequency of 5KHz, 8KHz, 10KHz, and 13KHz. The results show good agreements in wave forms between the measured voltage and current, and the difference between the measured and calculated one is less than 5%.