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

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

• 한국통신학회논문지
• /
• 제33권3A호
• /
• pp.304-310
• /
• 2008

In a wireless mesh network, there are two types of nodes: mesh routers and mesh clients. These two contradistinct network entities will be characterized and modeled depending on their role in the network. Mesh routers are essentially not mobile unlike the mesh clients. The differences on these nodes should be noted in any protocol design. In this paper, we present a mobility management for wireless mesh network (WMN). This mobility management handles movement of wireless mesh clients as it leaves from a coverage area of a wireless mesh router to another. We consider signaling overhead and mobility as performance metrics.

• 전기학회논문지P
• /
• 제60권3호
• /
• pp.120-125
• /
• 2011

When we design the grounding grid, dangerous voltage ANSI/IEEE Std. 80 method has been commonly used in the domestic area. However, the suitability of the ground rules for the design environment available. However, the suitability of the ground rules for the design environment available. In this paper, sticks according to the electrode conductor in combination with the mesh in order to design the ground by the IEEE Std.80 was designed. So in this paper, we examined of IEEE Std. 80 touch voltage method marginal utility and we induced for those problems by comparison between IEEE Std. 80 touch voltage value and simulation experimentation value. Furthermore, this paper presents a new design grounding system method that complements the IEEE Std. 80 method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 하계학술대회 논문집 B
• /
• pp.841-843
• /
• 2002

A novel and simple method, which can be used to automatically regenerate 3D finite element meshes, is presented in the paper. This technique based on the structural deformation analysis. It is problem independent and can be used to renew the mesh of any kind of 3D shape design system whether the geometric surface is parameterized or not. The mesh deformation degree can be adjusted by choosing suitable subregion and giving proper parameters. It is sufficient to obtain a smooth contour with proper mesh quality. Application to the optimum design of shielding plate shows the effectiveness of the proposed technique.

• Journal of Computational Design and Engineering
• /
• 제1권2호
• /
• pp.88-95
• /
• 2014

Because the cost of performance testing using actual products is expensive, manufacturers use lower-cost computer-aided design simulations for this function. In this paper, we propose using hexahedral meshes, which are more accurate than tetrahedral meshes, for finite element analysis. We propose automatic hexahedral mesh generation with sharp features to precisely represent the corresponding features of a target shape. Our hexahedral mesh is generated using a voxel-based algorithm. In our previous works, we fit the surface of the voxels to the target surface using Laplacian energy minimization. We used normal vectors in the fitting to preserve sharp features. However, this method could not represent concave sharp features precisely. In this proposal, we improve our previous Laplacian energy minimization by adding a term that depends on multi-normal vectors instead of using normal vectors. Furthermore, we accentuate a convex/concave surface subset to represent concave sharp features.

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

• 한국지능시스템학회:학술대회논문집
• /
• 한국퍼지및지능시스템학회 2005년도 춘계학술대회 학술발표 논문집 제15권 제1호
• /
• pp.139-142
• /
• 2005

This paper describes an automatic finite element (FE) mesh generation for three-dimensional structures consisting of free-form surfaces. This mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of nodes, and (c) generation of elements. One of commercial sol id modelers is employed for three-dimensional sol id structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well control led by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of FE meshes for three-dimensional sol id structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for three-dimensional complex geometry.

• 한국CDE학회논문집
• /
• 제1권1호
• /
• pp.65-75
• /
• 1996

This paper describes an automatic finite element(FE) mesh generation for three-dimensional structures consisting of free-form surfaces. This mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of nodes, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid and shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of FE meshes for three-dimensional solid and shell structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for three-dimensional complex geometry.

• 한국CDE학회논문집
• /
• 제8권1호
• /
• pp.10-18
• /
• 2003

FEM (Finite Element Method) is a fundamental numerical analysis technique in wide spread use in engineering application. As the solving time occupies small portion of entire FEM analysis time because of development of hardware, the relative lime to the whole analysis time to make mesh mod-els is growing. In particular, in the case of stiffeners such as features attached to plate in ship structure, the line constraints are imposed on mesh model together with other constraints such as holes. To auto-matically generate two dimensional quadrilateral mesh with the line constraints, an algorithm is pro-posed based on the constrained Delaunay triangulation and Q-Morph algorithm in which the line constraints are not considered. The performance of the proposed algorithm is evaluated. And some numerical results of our proposed algorithm ate presented.