• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1177-1180
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• 2007

This paper has the objects of deciding dynamic instability regions of thick plates by finite element method and providing kinematic design data for mats and slabs of building structures. In this paper, dynamic stability analysis of tapered opening thick plate is done by use of Serendipity finite element with 8 nodes considering shearing strain of plate. To verify this finite element method, buckling stress and natural frequencies of thick pate with or without in-plane stress are compared with existing solutions. The results are as follow that this finite element solutions with $4{\times}4$ meshes are shown the error of maximum 0.56% about existing solutions, and obtained dynamic instability graph according with variation of opening positions.

• 대한수학회지
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• 제49권3호
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• pp.549-569
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• 2012

In this paper asymptotic error expansions for mixed finite element approximations to a class of second order elliptic optimal control problems are derived under rectangular meshes, and the Richardson extrapolation of two different schemes and interpolation defect correction can be applied to increase the accuracy of the approximations. As a by-product, we illustrate that all the approximations of higher accuracy can be used to form a class of a posteriori error estimators of the mixed finite element method for optimal control problems.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.955-962
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• 2006

This paper has the objects of deciding dynamic instability regions of thick plates on Pasternak foundation by finite element method and providing kinematic design data for mats and slabs of building structures. In this paper, dynamic stability analysis of tapered opening thick plate is done by use of Serendipity finite element with 8 nodes considering shearing strain of plate. To verify this finite element method, buckling stress and natural frequencies of thick pate with or without in-plane stress are compared with existing solutions. The results are as follow that this finite element solutions with 4x4 meshes are shown the error of maximum 0.56% about existing solutions, and obtained dynamic instability graph according with variation of opening positions.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권4호
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• pp.174-181
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• 1999

To obtain more accurate result in the finite element analysis for electric machinery, it is important to have a mesh being of good quality. This paper describes a new technique of mesh generation for the finite element method. When the list of points defining the region of analysis is given, an appropriate distribution of interior points is generated first. Secondly the points are connected to from the trianlges. Finally the connectivity data are used to reposition the interior points using Laplacian smoothing and mesh relaxation technique. In this paper, a mesh searching technique of Lawson which modifies the start mesh is proposed in addition to the above three steps. This algorithm is simple and produces the meshes being of good quality with high speed in comparison with the existing one.

• 한국정밀공학회지
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• 제22권12호
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• pp.100-107
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• 2005

The present work covers a new ray tracing scheme of an injection-molded plastic lens linked with finite element analysis fur injection molding processes. The traditional ray tracing schemes have been based on the assumption that optical property of the lens is homogeneous throughout the entire volume. However, this assumption is quite unrealistic for injection-molded plastic lenses since material properties vary at every point due to injection molding effects. In order to consider non-homogeneous property of a lens, a modified ray tracing method is proposed in connection with finite element analysis of injection molding. Through the analysis of the injection molding process, the distribution of refractive indices can be obtained. This information is then utilized in the proposed ray tracing scheme based on finite element meshes so as to take into account variation of the refractive indices. The effect of mold temperature is also investigated through finite element analysis, and the relevant optical quality is evaluated through the proposed ray tracing simulation.

• 한국방재학회 논문집
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• 제9권1호
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• pp.9-13
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• 2009

본 연구는 적응적 요소망을 사용한 유한요소법으로 해석된 2차원 문제를 전산을 활용한 구조공학 교육의 중요한 부분으로 활용하는 대요를 제시한다. 적응적 요소망 형성방법에서는 비교적 간단한 요소의 대표 변형률 값을 사용하였고 유한요소법으로는 광범위하게 활용되고 있는 변위법을 사용하였다. 적용한 예제는 기본 역학의 대표적인 문제인 집중 하중을 받는 캔틸레버보와 중앙에 원형 구멍을 갖은 평판 인장 문제이다. 교육 대요와 예제는 적응적 요소망을 사용한 유한요소법이 전산을 활용한 구조공학 교육에 중요한 부분이 될 수 있는 것을 보여준다.

• 전산구조공학
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• 제1권2호
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• pp.83-90
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• 1988

본 연구에서는 평판 구조물의 해석을 위한 개선된 유한요소를 제시하였다. 이 요소는 Mindlin 평판이론에 의하여 수식화되었으며, 'Heterosis'평판요소의 변위장에 비적합변위형을 추가함으로써 유도되었다. 본 연구에서 제시한 평판요소는 요소의 강체운동과 관련된 Zero Eigenvalue만을 갖고 있으므로 Spurious Zero Energy Mode를 보이지 않는다. 대표적인 문제에 대한 수치해석을 해 본 결과 본 연구에서 제시한 평판요소는 우수한 수렴도를 보여 주었으며, 아주 얇은 평판문제에서도 요소의 형상에 관계없이 Shear Locking현상을 극복하였다.

• 대한설비공학회지:설비저널
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• 제13권2호
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• pp.10-15
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• 1984

The aims of this study are to obtain a suitable method and a proper mesh for investigation of the temperature distribution and heat transfer. The relative errors of temperature distribution and heat transfer for each mesh are acquired in accordance with linear finite element (FEM 3), square finite element (FEM 6), cubic finite element (FEM 10), and finite difference method (FDM). It has been found that FEM 10 is the most accurate measure to obtain the temperature distribution and heat transfer. However, no significant results have been obtained successfully, because when higher order finite element methods are used the more computational efforts are necessary due to the distribution of elements. The results of this study are as follows ; 1 . In case of a=b=L, meshes for less than $1\%$ relative errors (temperature distribution) acquired in various methods to exact solution are $2\times2,\;4\times4,\;8\times8\;and\;8\tiems8$ for each FEM 10, FEM 6, FEM 3 and FDM and a=L, b=1/2L are $10\times5$ for each FEM 3 and FDM. And the tendency of results acquired of heat transfer is similar to those above. 2 . In computational efforts (a=b=L), FEM 6 has taken 21 times. and FEM 10 154times FEM 3 and FDM and FEM 3 is the sane as FDM.

• 대한기계학회논문집A
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• 제34권8호
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• pp.1007-1013
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• 2010

본 연구에서는 NURBS 의 국부 세분화 방법 중 하나인 계층적 B-스플라인을 이용해 스플라인 유한요소법의 국부 세분화를 수행하는 방법을 제안한다. 세분화가 필요한 영역에 전역 격자로부터 계층적으로 생성된 국소 격자를 중첩시켜 국부 세분화를 수행한다. 국소 격자의 매듭 벡터와 제어점은 전역 격자로부터 추출된 후 세분화 되는 과정을 거친다. 생성된 국소 격자에 적절한 연속성 조건을 부여 함으로써 전역 격자와 국소 격자의 연속성을 유지 한다. 제안된 방법을 이용해 수치 예제의 해석을 수행하였다. 이를 통해 기존 NURBS 기반 스플라인 유한요소법에 비해 제안된 방법의 효율성을 검증하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.169-176
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• 2002

This paper is concerned with development of an enhanced quadratic Mindlin plate bending element. The behavior of the proposed plate element is further improved by the coupled use of non-conforming displacement modes, the selectively reduced integration scheme, and the assumed shear strain fields. The improvement may be attributable to the fact that the merits of these improvement techniques are merged in the formation of the new element in a complementary manner. The proposed quadratic finite element passes the patch tests, does not show spurious mechanism, and does not produce shear locking phenomena even with distorted meshes. It is shown that the element produces reliable solutions through numerical tests for standard benchmark problems. It is also noted that the element is applicable to transient dynamic analysis of Mindlin plates.