• The KIPS Transactions:PartA
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• v.19A no.4
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• pp.169-174
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• 2012

We present an algorithm that computes a 3 dimensional Voronoi diagram for a protein molecule in this paper. The molecule is represented as a set of spheres with van der Waals radii. The Voronoi diagram is constructed in the 3D space by finding the voxels containing it. For the feasibility of the computation, we represent the molecule as a BVH (bounding volume hierarchy), and our system is accelerated by modern graphics hardware with CUDA programming support. Compared to single-core CPU implementations, experimental results show 323 times faster performance in the computation time, when the space is partitioned into $2^{24}$ voxels.

• Journal of the Korea Computer Graphics Society
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• v.5 no.2
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• pp.9-23
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• 1999

Visibility preprocessing is a useful method to reduce the complexity of scenes to be processed in real-time, and so enhances the overall rendering performance for interactive visualization of virtual environments. In this paper, we propose an efficient visibility preprocessing method. In the proposed method, we assume that navigatable areas in virtual environments are partitioned into rectangular parallelpiped cells or sub-worlds. To preprocess the visibility of each polygon for a given partitioned cell, we should determine at least the area-to-area visibility. This is inherently a four-dimensional problem. We efficiently express four-dimensional visibility information on two-dimensional spaces and keep it within a ternary tree, which is conceptually similar to a BSP(Binary Space Partitioning) tree, by exploiting the characteristics of conservative visibility. The proposed method is able to efficiently handle more general environments like urban scenes, and remove invisible polygons jointly blocked by multiple occluders. The proposed method requires O(nm) time and O(n+m) space. By selecting a suitable value for m, users can select a suitable level of trade-off between the preprocessing time and the quality of the computational result.

• Korean Journal of Computational Design and Engineering
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• v.3 no.3
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• pp.154-160
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• 1998

In this study, we implement the prototype modeler with non-manifold data structure using Open Inventor. In these days, Open Inventor is a popular tool for computer graphics applications, even though Open Inventor could not store topological information including a non-manifold data structure which can represent an incomplete three dimensional shape such as a wireframe and a dangling surface during designing. Using Open Inventor, our modeler can handle a non-manifold model whose data structure is based on the radial edge data structure. A model editor is also implemented as an application which can construct a non-manifold model from two dimensional editing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.140-142
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• 2011

In this paper, special purpose arithmetic unit for mobile graphics accelerator is designed. The designed processor supports six operations, such as $1/{\chi}$, $\frac{1}{{\sqrt{x}}$, $log_2x$, $2^x$, $sin(x)$, $cos(x)$. The processor adopts 2nd-order polynomial minimax approximation scheme based on IEEE floating point data format to satisfy accuracy conditions and has 5-stage pipeline structure to meet high operational rates. The SFAU processor consists of 23,000 gates and its estimated operating frequency is about 400 Mhz at operating condition of 65nm CMOS technology. Because the processor can execute all operations with 5-stage pipeline scheme, it has about 400 MOPS(million operations per second) execution rate. Thus, it can be applicable to the 3D mobile graphics processors.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.411-419
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• 2006

In this study, a new approach employing 3-dimensional strut-tie models for analysis and design of 3-dimensional structural concrete with disturbed regions that are not properly occupied by current design codes is proposed. In addition, a computer graphics program for the practical application of the approach is developed. The approach adopts a grid strut-tie model to exclude the subjectivity in the selection of strut-tie model and evaluates the effective strength of concrete strut by considering the 3-dimensional failure criteria of concrete and the deviation angles between the struts and compressive principal stress trajectories. To verify the appropriateness of the approach, nine pile caps tested to failure are analyzed and a bridge pier is designed. The analysis and design results are compared with those obtained by several different methods.

• Journal of the Korea Computer Graphics Society
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• v.3 no.2
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• pp.85-97
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• 1997

This study is intended to propose methods of iso-surfaces representation in visualizing the stress distribution in 3-dimensional solids computed by finite element method, and to develop efficient algorithms related to iso-surfaces, and also to exploit the practical application to various data visualizations. This paper suggests practical methods of creating and rendering iso-surfaces, and methods of surface smoothing which removes local irregularity on the surface. Also devised in this study are various methods of rendering stress distribution with the aid of iso-surfaces. Their effectiveness and usefulness have been tested and verified through actual implementaion of a finite element analysis software and case studies using the software.

• Journal of the Korea Computer Graphics Society
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• v.3 no.2
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• pp.55-63
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• 1997

This paper presents a method of detecting motion isometry from the motions of two objects in a three-dimensional space. We define the motion isometry based on the group theory and a newly defined coordinate system. Motion isometry can be detected using the coordinate system which we call Motion Specific Coordinate System(MSCS). In addition, we present an algorithm if two motions are isometric using the coordinate system. The algorithm can detect the difference in the motions of objects irrespective of their positions or the directions of their motions in a space. The algorithm can also detect the motion difference in the case of segmented objects which have several joints. The motion quantity is represented by translation values or rotation angles about some axes.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.123-130
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• 2018

Triangulation is one of the fundamental problems in computational geometry and computer graphics community, and it has huge application areas such as 3D printing, computer-aided engineering, surface reconstruction, surface visualization, and so on. The Delaunay refinement algorithm is a well-known method to generate quality triangular meshes when point cloud and/or constrained edges are given in two- or three-dimensional space. In this paper, we propose a simple but efficient algorithm to triangulate Voronoi surfaces of Voronoi diagram of spheres in 3-dimensional Euclidean space. The proposed algorithm is based on the Ruppert's Delaunay refinement algorithm, and we modified the algorithm to be applied to the triangulation of Voronoi surfaces in two ways. First, a new method to deciding the location of a newly added vertex on the surface in 3-dimensional space is proposed. Second, a new efficient but effective way of estimating approximation error between Voronoi surface and triangulation. Because the proposed algorithm generates a triangular mesh for Voronoi surfaces with guaranteed quality, users can control the level of quality of the resulting triangulation that their application problems require. We have implemented and tested the proposed algorithm for random non-intersecting spheres, and the experimental result shows the proposed algorithm produces quality triangulations on Voronoi surfaces satisfying the quality criterion.

• Journal of computational fluids engineering
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• v.19 no.3
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• pp.52-61
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• 2014

The present paper deals with the efficient computation of higher-order CFD methods for compressible flow using graphics processing units (GPU). The higher-order CFD methods, such as discontinuous Galerkin (DG) methods and correction procedure via reconstruction (CPR) methods, can realize arbitrary higher-order accuracy with compact stencil on unstructured mesh. However, they require much more computational costs compared to the widely used finite volume methods (FVM). Graphics processing unit, consisting of hundreds or thousands small cores, is apt to massive parallel computations of compressible flow based on the higher-order CFD methods and can reduce computational time greatly. Higher-order multi-dimensional limiting process (MLP) is applied for the robust control of numerical oscillations around shock discontinuity and implemented efficiently on GPU. The program is written and optimized in CUDA library offered from NVIDIA. The whole algorithms are implemented to guarantee accurate and efficient computations for parallel programming on shared-memory model of GPU. The extensive numerical experiments validates that the GPU successfully accelerates computing compressible flow using higher-order method.

• Journal of the Korea Computer Graphics Society
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• v.2 no.1
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• pp.39-47
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• 1996

Consumer's needs, pursuing diverse lifestyles, can be identified systematically by the development of design research method with computer technologies. Color, which is the most important factor in industrial design, has been regarded as possessing difficulties in collecting and analyzing reliable data, because it has multi-dimensional features. The purpose of this paper is to develop a new research method for design and color preference investigation, and to provide the possibilities of applying this method into the traditional color research which has many limitations in time, space, and money. This paper emphasizes that the new method using visual and concrete 3D modeling of a product can enhance the reliability of collecting and analyzing data comparing with traditional linguistic and abstract one.