• 한국컴퓨터그래픽스학회논문지
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• 제18권1호
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• pp.29-34
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• 2012

양질의 사면체 요소망은 유한요소법 기반의 변형체 시뮬레이션이나 사면체 기반의 유체 시뮬레이션 등에서 필수적이다. 본 논문에서는 옥트리 기반의 적응적 부호거리장을 이용하여 다각형 표면을 가진 물체의 내부를 양질의 이면각을 가진 사면체로 채우는 볼륨 요소망 구성 방법을 제안한다. 옥트리를 이용하여 물체 내부에서 표면까지 다양한 크기의 사면체를 이용하여 생성된 요소의 개수를 줄이며, 옥트리의 인접 셀들 사이의 레벨 차이를 제한하여 양질의 이면각을 가진 요소망을 얻는다. 옥트리 기반의 요소망 생성에 있어서 물체 표면까지의 부호거리를 구하는 것은 매우 중요한 연산이다. 본 논문은 하향식으로 생성한 옥트리의 꼭짓점들에서 부호거리장을 빠르게 구하는데 중점을 두고 있다. 본 논문에서 제안한 사면체 요소망 구성 방법은 실행 시간이 빠르고 안정적이며 구현이 쉬운 장점을 가지고 있다.

• 한국컴퓨터그래픽스학회논문지
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• 제17권2호
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• pp.45-53
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• 2011

본 논문에서는 양질의 이면각을 가진 사면체로 물체 내부를 채우는 볼륨 요소망 구성 방법을 제안한다. 본 논문에서 제안한 방법은 실행시간이 빠르고 안정적이며 구현이 쉬운 장점을 가지고 있다. 효율적인 공간 활용을 위해 옥트리를 사용함으로써 물체 내부에서 표면에 이르기까지 다양한 크기의 사면체를 활용할 수 있다. 최소 이면각을 최대화하고 최대 이면각을 최소화하는 양질의 요소망을 얻기 위하여 옥트리의 인접 셀들 사이의 레벨 차이를 제한하며, 옥트리 및 요소망 생성 속도를 높이기 위하여 정규 격자에서의 부호거리장을 사용한다. 본 논문에서 제안한 요소망 구성 방법은 유한요소법 기반의 변형체 시뮬레이션이나 사면체 기반의 유체 시뮬레이션 등에서 유용하게 활용될 수 있다.

• 한국정밀공학회지
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• 제21권3호
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• pp.91-99
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• 2004

An unstructured tetrahedral mesh generation algorithm has been presented. In order to construct better meshes in interior region by using an advancing front technique, a connecting operator and a local finishing operator II have been developed in addition to the existing operators. Before applying digging operators that generate new nodes inside of a meshing region, a connecting operator is employed that uses existing nodes which satisfy certain conditions for producing well-conditioned elements. The local finishing operator II is introduced to terminate the meshing process more flexibly on remaining subregions. With these new operators, tetrahedral meshing process becomes more robust and good quality of meshes are constructed.

• 대한기계학회논문집A
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• 제24권1호
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• pp.196-205
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• 2000

Computed Tomography (CT), Nuclear Magnetic Resonance Imaging (MR1) and some ultrasound techniques make it possible to obtain cross sections of human body or mechanical parts. In CAD system, a series of sectional surfaces can also be obtained from solid models of 3D objects. In this paper we introduce a tetrahedral meshing algorithm from these series of general sections using basic operators. In this scheme. general sections of three-dimensional object are triangulated first and side surfaces between two sections are triangulated by the use of tiling process. Finally tetrahedral meshing process is performed on each layer of 3D objects, which is composed of two general sections and one side surface.

• 대한기계학회논문집A
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• 제24권9호
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• pp.2397-2405
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• 2000

The remeshing is a method to replace a distorted mesh by a new mesh without interrupting the finite element calculation. The remeshing procedure in this paper refers to the rezoning, for which a sm oothing process is developed to alleviate the distortions of mesh. In the paper, an automatic finite element rezoning system with tetrahedral elements for large deformation analysis has been developed. Our smoothing process is composed of two steps, a surface smoothing and a volume smoothing. In the surface smoothing, checking the dihedral angle and projection on surface patch reduced the change of shape and nodes penetrating die. The constrained Laplacian smoothing has been employed for the volume smoothing process. The state variables are mapped from old mesh to new mesh by using volume coordinates within a tetrahedral element. All these procedures have been linked to the NIKE3D program As illustrated in the examples the overall strategy ensures a robust and efficient rezoning scheme for finite element simulation of metal-forming processes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.150-153
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• 2002

The use of the finite element method for biomechanical analysis is increasing rapidly in recent years. Since biomechanical models are usually in very complex shapes, it takes a lot of time and efforts to build reasonable finite element models. In this paper, a new tetrahedral meshing algorithm from the series of 2-D computed tomography(CT) images has been proposed. In this scheme, the planar sections of three-dimensional objects and the side surfaces between two planar sections are triangulated first, and then an advancing front algorithm is employed to construct tetrahedral elements by using basic operators. A sample finite element model for thoracic vertebra is presented.

• 대한기계학회논문집A
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• 제28권10호
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• pp.1517-1525
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• 2004

Shell finite elements are widely used for the analysis of thin section objects such as sheet metal parts, automobile bodies and et al. due to their computational efficiency. Since many of input data for finite element analysis are given as solid models or triangulated surface models, one should extract midsurface information from these input data initially and then construct shell meshes on the extracted midsurfaces. In this paper, a method of generating shell elements on midsurfaces directly from input models has been proposed, in which midsurface generating process can be omitted. In order to construct shell meshes, the input models should be triangulated on surfaces first, and then tetrahedral elements are generated by using an advancing front method, and finally mid shell surfaces are obtained from tetrahedral meshes. Some examples are given to demonstrate the efficiency of the proposed method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.700-705
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• 2004

Shell finite elements are widely used for the analysis of thin section objects such as sheet metal parts, automobile bodies and et al. due to their computational efficiency. Since many of input data for finite element analysis are given as solid models or triangulated surface models, one should extract midsurface information from these input data initially and then construct shell meshes on the extracted midsurfaces. In this paper, a method of generating shell elements on midsurfaces directly from input models have been proposed. In order to construct shell meshes, the input models should be triangulated on surfaces first, and then tetrahedral elements are generated by using an advancing front method, and finally mid shell surfaces are obtained from tetrahedral meshes. Some examples are given to demonstrate the efficiency of the proposed method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1605-1608
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• 2003

A unstructured tetrahedral mesh generation algorithm has been presented. To make better meshes in interior region using an advancing front technique, a connecting operator has been developed in addition to the existing operators. Before applying digging operators that generate new nodes inside of a meshing region, a connecting operator is employed that uses existing nodes which satisfy certain conditions for producing well-conditioned elements if possible. By introducing this new operator, tetrahedral meshing process becomes more robust and produces better quality of meshes.

• 한국CDE학회논문집
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• 제8권1호
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• pp.41-47
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• 2003

In this paper, a tetrahedral mesh generation algorithm which uses a grid based method for interior region and an advancing front method for outer surface region is proposed. In order to apply an advancing front method for outer region of an object, a new operator so called a hole operator has been developed to handle multiple shells. With this grid based approach in the interior region, more stable and uniform meshes can be constructed especially in the interior region.