• Journal of Computational Design and Engineering
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• v.1 no.1
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• pp.1-12
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• 2014

In this paper, we propose a new method of reconstructing the hand models for individuals, which include the link structure models, the homologous skin surface models and the homologous tetrahedral mesh models in a reference posture. As for the link structure model, the local coordinate system related to each link consists of the joint rotation center and the axes of joint rotation, which can be estimated based on the trajectories of optimal markers on the relative skin surface region of the subject obtained from the motion capture system. The skin surface model is defined as a three-dimensional triangular mesh, obtained by deforming a template mesh so as to fit the landmark vertices to the relative marker positions obtained motion capture system. In this process, anatomical dimensions for the subject, manually measured by a caliper, are also used as the deformation constraints.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.8
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• pp.751-756
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• 1991

In this paper, three dimensional magnetostatic fields are analysed using tetrahedral edge elements, magnetic vector potential and modified formulation of weighted residual method. If we define unknown variables in mesh edges, some conditions, such as Coulomb gauge condition in magnetic vector potential are naturally satisfied. So with less memory space, we can obtain more accurate solutions than the method where unknown variables are defined at nodes. Reliability and utility of this method are verified in two examples.

• Journal of Korean Society for Quality Management
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• v.22 no.2
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• pp.154-165
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• 1994

A new criterion, the solid angle, is introduced to measure the Quality of tetrahedral mesh. This criterion is compared with the existing Delaunay triangulation criterion. The properties of solid angles have been studied and are proposed for utilization in 3-D meshing algorithms. Furthermore, difficulties of developing a 3-D algorithm that provides a lower bound on the smallest angle have been discussed.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1487-1492
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• 2007

In this paper, we apply a forging simulator to automatic simulation of a connecting-rod forging process and compare its results with others found in the literature. The process information comes from the distributed examples of DEFORM3D. The process is fully automatically simulated using the tetrahedral element capability of AFDEX3D, developed by the authors. Our results are compared with the results found from the related literature, already simulated using DEFORM3D by other researchers. The comparison shows that our results are relatively excellent especially in terms of mesh quality on which the solution accuracy depends mainly.

• Wind and Structures
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• v.5 no.2_3_4
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• pp.89-100
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• 2002

Accidental gaseous losses from industrial processes can pose considerable health and environmental risks but assessing their health, safety and environmental impact is problematic. Improved understanding and simulation of the dispersion of emissions in the vicinity of storage tanks is required. The present study aims to assess the capability of the turbulence closures and meshing alternatives in a commercially available CFD code for predicting dispersion in the vicinity of cubes and circular cylindrical storage tanks. The performance of the $k-{\varepsilon}$ and Reynolds Stress turbulence models and meshing alternatives for these cases are compared to experimental data. The CFD simulations are very good qualitatively and, in many cases, quantitatively. A mesh with prismatic elements is more accurate than a tetrahedral mesh. Overall the Reynolds stress model performs slightly better than the $k-{\varepsilon}$ model.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.99-102
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• 2005

An approach to adaptive finite element analysis of three-dimensional forging processes is presented in this paper. In the approach, an optimal tetrahedral element generation technique is employed and the mesh density is specified by the combination of the normalized effective strain and the normalized effective strain rate. The approach is applied to computer simulation of an enclosed die forging process of a bevel gear and its results are compared with experiments.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1348-1358
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• 2004

The filling pattern and an adaptive grid refinement based on the finite element method and Eulerian mesh advancement approach have been developed to analyze incompressible transient viscous flow with free surfaces. The governing equation fur flow analysis is Navier-Stokes equation including inertia and gravity effects. The mixed FE formulation and predictor-corrector method are used effectively for unsteady numerical simulation. The flow front surface and the volume inflow rate are calculated using the filling pattern technique to select an adequate pattern among seven filling patterns at each tetrahedral control volume. By adaptive grid refinement, the new flow field that renders better prediction in flow surface shape is generated and the velocity field at the flow front part is calculated more exactly. In this domain the elements in the surface region are made finer than those in the remaining regions for more efficient computation. The collapse of a water dam and the filling of a fluidity spiral have been analyzed. The numerical results have been in good agreement with the experimental results and the efficiency of the adaptive grid refinement and filling pattern techniques have been verified.

• Journal of the Korean earth science society
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• v.38 no.1
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• pp.80-90
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• 2017

To build tetrahedra mesh for FEM numerical analysis, Boundary Representation (B-Rep) model is required, which provides the efficient volume description of an object. In engineering, the parametric solid modeling method is used for building B-Rep model. However, a geological modeling generally adopts discrete modeling based on the triangulated surface, called a Sealed Geological Model, which defines geological domain by using geological interfaces such as horizons, faults, intrusives and modeling boundaries. Discrete B-Rep model is incompatible with mesh generation softwares in engineering because of discrepancies between discrete and parametric technique. In this research we have developed a converting program from Sealed Geological Model to Gmsh and COMSOL software. The developed program can convert complex geological model built by geomodeling software to user-friendly FEM software and it can be applied to geoscience simulation such as geothermal, mechanical rock simulation etc.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2410-2413
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• 2005

Finite element method (FEM) has been widely used as a useful numerical method that can analyze complex engineering problems in electro-magnetics, mechanics, and others. CEMTool, which is similar to MATLAB, is a command style design and analyzing package for scientific and technological algorithm and a matrix based computation language. In this paper, we present new 3D FEM package in CEMTool environment. In contrast to the existing CEMTool 2D FEM package and MATLAB PDE (Partial Differential Equation) Toolbox, our proposed 3D FEM package can deal with complex 3D models, not a cross-section of 3D models. In the pre-processor of 3D FEM package, a new 3D mesh generating algorithm can make information on 3D Delaunay tetrahedral mesh elements for analyses of 3D FEM problems. The solver of the 3D FEM package offers three methods for solving the linear algebraic matrix equation, i.e., Gauss-Jordan elimination solver, Band solver, and Skyline solver. The post-processor visualizes the results for 3D FEM problems such as the deformed position and the stress. Consequently, with our new 3D FEM toolbox, we can analyze more diverse engineering problems which the existing CEMTool 2D FEM package or MATLAB PDE Toolbox can not solve.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.496-500
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• 1997

This paper describes an automated system for analyzing the stress intensity factors(SIFs) of three-dimensional (3D) cracks. A geometry model, i.e.a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-noded quadratic tetrahedral solid elements are generated by the Delauuay triangulation techniques. The singular elements such that the mid-point nodes near crack fornt are shifted at the quarter-points are automatically placed along the 3D crack front. THe complete finite element (FE) model generated, i.e the mesh with material properties and boundary conditions is given to one of the commercial FE codes, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performance of the present system, a semi- elliptical surface crack in a plate subjected to tension is solved.