• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7C
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• pp.594-597
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• 2010

This paper estimates belief-propagation (BP) decoding performance of moderate-length irregular low-density parity-check (LDPC) codes with sphere bounds. We note that for moderate-length($10^3{\leq}N{\leq}4\times10^3$) irregular LDPC codes, BP decoding performance, which is much worse than maximum likelihood (ML) decoding performance, is well matched with one of loose upper bounds, i.e., sphere bounds. We introduce the sphere bounding technique for particular codes, not average bounds. The sphere bounding estimation technique is validated by simulation results. It is also shown that sphere bounds and BP decoding performance of irregular LDPC codes are very close at bit-error-rates (BERs) $P_b$ of practical importance($10^{-5}{\leq}P_b{\leq}10^{-4}$).

• Korean Journal of Computational Design and Engineering
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• v.20 no.4
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• pp.321-327
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• 2015

In the protein database search, 3D structural shape comparison for protein screening plays a important role. Protein databases have big size and have been grown rapidly. Exhaustive search methods cannot provide a satisfactory performance. As protein is composed of a set of spheres, the similarity calculation of two set of spheres is very expensive. Thus, a reasonable filtering method could be an answer for the speedup of protein screening. In this paper, we suggest a speedup method for protein screening with atom number and bounding sphere. We also show some experimental results for the validity of our method.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11a
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• pp.451-454
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• 2002

충돌검사는 사실감 있는 3 차원 공간을 시뮬레이션 하기 위해서 필수적인 요소이다. 본 논문에서는 BSP 로 표현될 수 있는 정적 게임환경과 Bounding Sphere 로 표현될 수 있는 움직이는 물체와의 효과적인 충돌검사 방법에 대해서 기술하고 있다. 본 논문에서 제안하는 충돌검사 알고리즘은 단 하나의 BSP 트리를 사용하여 임의의 크기의 bounding sphere 와 충돌검사를 할 수 있다는 장점을 가진다.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2402-2406
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• 2005

A collision query determines the intersection between given objects, and is used in computer-aided design and manufacturing, animation and simulation systems, and physically-based modeling. Bounding volume hierarchies are one of the simplest and most widely used data structures for performing collision detection on complex models. In this paper, we present hierarchy of oriented rounded bounding volume for fast proximity queries. Designing hierarchies of new bounding volumes, we use to combine multiple bounding volume types in a single hierarchy. The new bounding volume corresponds to geometric shape composed of a core primitive shape grown outward by some offset such as the Minkowski sum of rectangular box and a sphere shape. In the experiment of parallel close proximity, a number of benchmarks to measure the performance of the new bounding box and compare to that of other bounding volumes.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.2
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• pp.59-64
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• 2014

This paper presents a method for estimating the bounding volume for image-based 3D object reconstruction. The bounding volume of an object is a three-dimensional space where the object is expected to exist, and the size of the bounding volume strongly affects the resolution of the reconstructed geometry. Therefore, the size of a bounding volume should be as small as possible while it encloses an actual object. To this end, the proposed method uses a set of silhouettes of an object and generates a point cloud using a point filter. A bounding volume is then determined as the minimum sphere that encloses the point cloud. The experimental results show that the proposed method generates a bounding volume that encloses an actual object as small as possible.

• Journal of Information Processing Systems
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• v.8 no.4
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• pp.713-720
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• 2012

Unlike FEM (Finite Element Method), which provides an accurate deformation of soft objects, FFD (Free Form Deformation) based methods have been widely used for a quick and responsive representation of deformable objects in real-time applications such as computer games, animations, or simulations. The FFD-AABB (Free Form Deformation Axis Aligned Bounding Box) algorithm was also suggested to address the collision handling problems between deformable objects at an interactive rate. This paper proposes an enhanced FFD-AABB algorithm to improve the frame rate of simulation by adding the bounding sphere based collision test between 3D deformable objects. We provide a comparative analysis with previous methods and the result of proposed method shows about an 85% performance improvement.

• The Journal of the Korea Contents Association
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• v.8 no.4
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• pp.17-29
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• 2008

In Computer Graphics, fluid dynamics is used for animating and expressing the various special effects of water. As the hardware performance is getting higher, the several algorithms for fluid dynamics become to be executed in real time. However, it still requires a lot of computational time to get the realistic and detailed results. Therefore, there are many researches on the techniques of balancing between performance and quality. It must give priority to the executive performance preserving the visual reality even though sacrificing the physical reality, specially in applications with the game context which need to express the interaction between 3D objects and the surface of the water such as the sea or a lake. In this paper, we propose a method for the realtime animation of interactions between 3D objects and the surface of the water using the linear convolution of height fields and the bounding spheres of object.

• Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.55-66
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• 2015

To satisfy safety regulations of Economic Commission for Europe (ECE), the surface regions of automobile parts must have a sufficient degree of roundness if there is any chance that they could contact a sphere of 50.0 mm radius (exterior parts) or 82.5 mm radius (interior parts). In this paper, a new offset-based method is developed to automatically detect the possible sphere-contacting shape of such parts. A polyhedral model that precisely approximates the part shape is given as input, and the offset shape of the model is obtained as the Boolean union of the expanded shapes of all surface triangles. We adopt a triple-dexel representation of the 3D model to enable stable and precise Boolean union computations. To accelerate the dexel operations in these Boolean computations, a new parallel processing method with a pseudo-list structure and axis-aligned bounding box is developed. The possible sphere-contacting shape of the part surface is then extracted from the offset shape as a set of points or a set of polygons.

• Communications of the Korean Mathematical Society
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• v.27 no.4
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• pp.815-834
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• 2012

In this paper, we characterize surgery presentations for $\mathbb{Z}$-homology 3-spheres and $\mathbb{Z}/2\mathbb{Z}$-homology 3-spheres obtained from $S^3$ by Dehn surgery along a knot or link which admits an even net diagram and show that the Casson invariant for $\mathbb{Z}$-homology spheres and the ${\mu}$-invariant for $\mathbb{Z}/2\mathbb{Z}$-homology spheres can be directly read from the net diagram. We also construct oriented 4-manifolds bounding such homology spheres and find their some properties.

• Communications of the Korean Mathematical Society
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• v.37 no.2
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• pp.371-384
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• 2022

Fix an integer n ≥ 1. Then the simplex Π_n, Birkhoff polytope Ω_n, and Latin square polytope Λ_n each yield projective geometries obtained by identifying antipodal points on a sphere bounding a ball centered at the barycenter of the polytope. We investigate conditions for homogeneous coordinates of points in the projective geometries to locate exact vertices of the respective polytopes, namely crisp distributions, permutation matrices, and quasigroups or Latin squares respectively. In the latter case, the homogeneous conditions form a crucial part of a recent projective-geometrical approach to the study of orthogonality of Latin squares. Coordinates based on the barycenter of Ω_n are also suited to the analysis of generalized doubly stochastic matrices, observing that orthogonal matrices of this type form a subgroup of the orthogonal group.