• 한국CDE학회논문집
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• 제9권1호
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• pp.1-10
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• 2004

In the process of finite element analysis, mesh generation is tedious job which consumes tremendous time. Therefore, the automation of well shaped mesh generation from the minimal boundary input data is desirable to improve reliability and accuracy of the analysis and also to reduce the process time of the entire design process. The automation of triangular mesh generation has been relatively well treated due to its robustness and ease of handling when compared to rectangular element mesh generation. In this study, the offset method developed previously for generating plane rectangular element mesh has been corrected and modified to generate triangular element mesh on the B-spline surface having arbitrary holes. The result shows that the generated triangular mesh has the average aspect ratio over 0.9. The designed arbitrary surface shape has been interactively constructed by non-uniform B-spline theory for triangular mesh generation.

• International Journal of CAD/CAM
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• 제1권1호
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• pp.11-21
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• 2002

This paper presents a triangular-to-quadrilateral mesh conversion method that can control the directionality of the output quadrilateral mesh according to a user-specified vector field. Given a triangular mesh and a vector field, the method first scores all possible quadrilaterals that can be formed by pairs of adjacent triangles, according to their shape and directionality. It then converts the pairs into quadrilateral elements in order of the scores to form a quadrilateral mesh. Engineering analyses with finite element methods occasionally require a quadrilateral mesh well aligned along the boundary geometry or the directionality of some physical phenomena, such as in the directions of a streamline, shock boundary, or force propagation vectors. The mesh conversion method can control the mesh directionality according to any desired vector fields, and the method can be used with any existing triangular mesh generators.

• 한국CDE학회논문집
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• 제11권2호
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• pp.107-114
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• 2006

A new quadrilateral mesh generation technique from an existing triangle mesh is proposed in this paper. The proposed method is based on advancing front method and zero-thickness layer. Beginning with an initial triangular mesh, boundary triangular elements are removed and quadrilateral elements with zero thickness are generated. A quality of quadrilateral elements is improved during a mesh smoothing process. Until all initial triangular elements are removed, this procedure is repeated. Sample meshes are constructed to demonstrate the mesh generation capability of proposed algorithm.

• 한국컴퓨터그래픽스학회논문지
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• 제16권3호
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• pp.31-39
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• 2010

직물을 모델링 할 때 사각 메쉬 기반의 파티클 시스템이 이미 제시된 바 있다. 그러나 일반적으로 삼각 메쉬를 사용하여 직물을 표현하므로 삼각 메쉬 기반의 직물 모델링이 필요하다. 삼각 메쉬를 이용한 직물 모델링은 보통 물질이 연속적이라고 가정하는 유한 요소법적인 방식을 사용한다. 본 논문은 파티클 시스템의 장점인 모델의 간단함, 구현의 용이성 등을 삼각 메쉬상에서도 살리기 위해 삼각 메쉬 기반의 파티클 시스템을 제안한다. 직물의 움직임은 메쉬 꼭지점들이 삼각 메쉬의 에지들을 통해 서로 상호작용하도록 모델링한다. 꼭지점들의 상호작용은 두 개의 구조, 즉 에지 연결 구조와 대각선 연결 구조를 이용하여 정의하고, 상호작용을 할 때 생성되는 변형 에너지는 탄성이론을 적용하여 모델링하였다. 사각 메쉬에 적용되었던 파티클 시스템의 장점 을 삼각 메쉬에 구현한 것이 본 논문의 공헌이다.

• 한국CDE학회논문집
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• 제14권1호
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• pp.33-41
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• 2009

Triangular mesh models are widely used in reverse engineering, computer graphics, rapid prototyping and NC(numerical controller) tool-path generation. Triangular mesh models are generated from point clouds, surface models and solid models. A halfedge-based triangular mesh data structure is proposed and the development considerations are presented. In the presented data structure, halfedge is the key data structure. Halfedge stores its triangle index and the order in the triangle. Triangles do not store the halfedge lists explicitly. Halfedge is referred by value and defined when it is required. Proposed data structure supports four design requirements: efficient rendering, compact memory, supporting efficient algorithms and easy programming.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.73-79
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• 2006

In this paper, we propose a new triangular finite element mesh generation method based on simplification of high-density mesh and adaptive Level-of-Detail (LOD) methods for efficient CAE. In our method, mesh simplification is used to control the mesh properties required for FE mesh, such as the number of triangular elements, element shape quality and size while keeping the specified approximation tolerance. Adaptive LOD methods based on vertex hierarchy according to curvature and region of interest, and global LOD method preserving density distributions are also proposed in order to construct a mesh more appropriate for CAE purpose. These methods enable efficient generation of FE meshes with properties appropriate for analysis purpose from a high-density mesh. Finally, the effectiveness of our approach is shown through evaluations of the FE meshes for practical use.

• 한국CDE학회논문집
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• 제4권2호
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• pp.79-86
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• 1999

A general approach to automatic generation of triangular meshes on three-dimensional surfaces is presented in this paper. The approach, developed with emphasis on program generality and interface with CAD/CAM systems, is based on the double mapping method and the looping method. The double mapping method is introduced and anew splitting scheme is proposed for the looping method employed for triangular mesh generation on the parametric domain. Several application examples are given.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(4)
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• pp.35-38
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• 2000

The method of Content-based Triangular Mesh Image representation in moving pictures makes better performance in prediction error ratio and visual efficiency than that of classical block matching. Specially if background and objects can be separated from image, the objects are designed by Irregular mesh. In this case this irregular mesh design has an advantage of increasing video coding efficiency. This paper presents the techniques of mesh generation, motion estimation using these mesh, uses image warping transform such as Affine transform for image reconstruction, and evaluates the content based mesh design through computer simulation.

• 한국CDE학회논문집
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• 제12권6호
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• pp.422-428
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• 2007

Presented in the paper is a procedure to reconstruct a triangular mesh from a point cloud. Although, the proposed procedure is based on the well-known Voronoi diagram approach, it introduces a selection method of 'Pole' to improve the quality of resulting mesh. To select the appropriate Poles for high quality of Triangular mesh, the patterns that the Poles affect to the mesh quality are carefully analyzed. It is possible to improve the mesh quality by controlling the selection method of 'Pole' in terms of distance limit. The initial mesh obtained by the proposed procedure may include invalid triangles. To relieve this problem, a slicing method is proposed to remove invalid triangles from the initial mesh. At last, correcting technique of normal vectors of generated mesh is introduced.

• 한국CDE학회논문집
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• 제20권1호
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• pp.44-54
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• 2015

Solving partial differential equations (PDEs) on a manifold setting is frequently faced problem in CAD, CAM and CAE. However, unlikely to a regular grid, solutions for those problems on a triangular mesh are not available in general, as there are no well-established intrinsic differential operators. Considering that a triangular mesh is a powerful tool for representing a highly-complicated geometry, this problem must be tackled for improving the capabilities of many geometry processing algorithms. In this paper, we introduce mathematically well-defined differential operators on a triangular mesh setup, and show some examples of their applications. Through this, it is expected that many CAD/CAM/CAE application will be benefited, as it provides a mathematically rigorous solution for a PDE problem which was not available before.