• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.114-118
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• 2005

In this study, the DC dielectric breakdown of epoxy composites used for molding material was experimented and then its data were simulated by Weibull distribution equation. From the analysis of Weibull distribution, it was confirmed that as the allowed breakdown probability was given by 0.1[%], the applied field value needed to be under 21.5[kV/mm].

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.362.1-362
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• 2002

Eigenvalues are taken as performance criteria for structural damping design using viscoelastic material. Given material properties, optimal distribution of damping material is sought based on eigenvalue sensitivity. For eigenanalysis of frequency dependent viscoelastic material rented structures, Golla-Hughes-McTavish(GHM) model is used and some dominant modes are chosen for consideration. (omitted)

• 대한토목학회논문집
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• 제30권5A호
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• pp.425-431
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• 2010

2가지 이상의 재료로 구성된 다상(multi-phase) 재료는 상 분포에 따라 재료 특성이 다르기 때문에, 상 분포를 묘사할 수 있는 적절한 방법이 필요하다. 본 연구에서는 확률 분포 함수 two-point correlation function과 lineal-path function을 사용하여 재료 내부의 상 분포 상태를 확률적으로 묘사하였다. 수치 계산 방법으로 계산되는 확률 분포 함수를 3개의 매개 변수를 사용한 곡선 접합(curve fitting)을 이용하여 수식으로 표현하고, 적용성을 살펴보기 위하여 2상 합금 미세구조 가상 시편과 지반 모델 시편을 사용하였다. 이를 통해, 확률 분포 함수는 곡선 접합을 이용하여 지수 형태의 수식으로 표현이 가능하며, 이는 시편의 RVE로서의 활용 가능성을 판단하는데 사용될 수 있음을 확인하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.66-69
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• 2005

Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.

• 한국환경과학회지
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• 제7권6호
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• pp.817-825
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• 1998

A three-dimensional ecosystem model is applied to the Suyoung Bay, located at the southeastern part of Korea, to study of the material distribution in the time scale of several tens days. The model has included of the DIN(Dissolved Inorganic Nitrogen), DIP(Dissolved Inorganic Phosphate), phytoplankton, zooplankton and detritus, and also was coupled with the physical processes. The spatial distribution of chlorophyll-a and primary productivity in the model is determined by the physical and chemical-biological parameters. The horizontal distributions of the DIN, DIP and chlorophyll-a are decreased from the coast to the off-shore, though the nutrients show some more complicated pattern than the chlorophyll-a. The nutrient contents in the off-shore are low, and thus a relatively low productivity(chlorophyll-a) are presented. On the whole, the distribution of the results of model are smoother than the observed ones and some small scale variation in the observed data cannot be reproduced by the model due to the resolution limits of model. However, the basic pattern and the quantitavities has been reproduced by the model well.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.605-610
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• 2002

Eigenvalues are taken as performance criteria for structural damping design using viscoelastic material. Given material properties, optimal distribution of damping material is sought based on eigenvalue sensitivity. For eigenanalysis of frequency dependent viscoelastic material treated structures, Golla-Mushes-McTavish (GHM) model is used and some dominant modes are chosen for consideration. To avoid the intensity of computation caused by increased problem size, an alternative approximate method is proposed which uses elastic modes and can be applied under small damping assumption. A cantilever beam treated with unconstrained viscoelastic layer is tested and optimal distribution of thickness of the layer is illustrated. Partial coverage configurations are compared with the one-sided full coverage case.

• 대한기계학회논문집A
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• 제30권2호
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• pp.164-170
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• 2006

To prevent the numerical instabilities in topology optimization, continuous approximation of material distribution (CAMD) is proposed to the homogenization design method (HDM) and the simple isotropic material with penalization (SIMP) method. The continuous FE approximation of design variables including high order elements is applied to the formulation of SIMP method. Numerical examples are presented to compare the efficiency of CAMD both in HDM and SIMP.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.66-68
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• 2001

Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators for transmission and distribution line have significant advantages over porcelain and glass insulators, especially for ultra-high voltage(UHV) transmission lines. Their advantages are light weight, vandalism resistance and hydrophobicity. In this paper, distribution polymer suspension insulator has been designed and investigated electric field distribution by FEM.

• 소성∙가공
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• 제5권2호
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• pp.156-164
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• 1996

To investigate the behavior of plastic deformation in axisymmetric extrusion through square dies, experimental works with the plasticine as a model material are carried out at the room temperature. Some mechanical properties of the model material are determined by compression and ring compression tests. Visioplasticity method using expermental grid distortion in extrusion is introduced to analyze the plastic flow strain rate and strain distribution. In spite of severe deformation during the extrusion through square die the visioplasticity method shows good results for the distribution of effective strain rate and effective strain.

• The Journal of Advanced Prosthodontics
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• 제3권3호
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• pp.140-144
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• 2011

PURPOSE. Finite element study on the effect of abutment length and material on implant bone interface against dynamic loading. MATERIALS AND METHODS. Two dimensional finite element models of cylinderical implant, abutments and bone made by titanium or polyoxymethylene were simulated with the aid of Marc/Mentat software. Each model represented bone, implant and titanium or polyoxymethylene abutment. Model 1: Implant with 3 mm titanium abutment, Model 2: Implant with 2 mm polyoxymethylene resilient material abutment, Model 3: Implant with 3 mm polyoxymethylene resilient material abutment and Model 4: Implant with 4 mm polyoxymethylene resilient material abutment. A vertical load of 11 N was applied with a frequency of 2 cycles/sec. The stress distribution pattern and displacement at the junction of cortical bone and implant was recorded. RESULTS. When Model 2, 3 and 4 are compared with Model 1, they showed narrowing of stress distribution pattern in the cortical bone as the height of the polyoxymethylene resilient material abutment increases. Model 2, 3 and 4 showed slightly less but similar displacement when compared to Model 1. CONCLUSION. Within the limitation of this study, we conclude that introduction of different height resilient material abutment with different heights i.e. 2 mm, 3 mm and 4 mm polyoxymethylene, does not bring about significant change in stress distribution pattern and displacement as compared to 3 mm Ti abutment. Clinically, with the application of resilient material abutment there is no significant change in stress distribution around implant-bone interface.