• Journal of Mechanical Science and Technology
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• 제14권10호
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• pp.1104-1113
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• 2000

This paper proposes an efficient reverse engineering technique for compound surfaces using a boundary detection method. This approach consists in extracting geometric edge information using a vision system, which can be used in order to drastically reduce geometric errors in the vicinity of compound surface boundaries. Through the image-processing technique and the interpolation process, boundaries are reconstructed by either analytic curves (e. g. circle, ellipse, line) or parametric curves (B-spline curve). In other regions, except boundaries, geometric data are acquired on CMM as points inspected using a touch type probe, and then they are interpolated on several surfaces using a B-spline skinning method. Finally, the boundary edge and the skinned surfaces are combined to reconstruct the final compound surface. Through simulations and experimental works, the effectiveness of the proposed method is confirmed.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.160-168
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• 1999

This paper describes one method of reverse engineering that machines a free form shape without descriptive model. A portable five-axes 3D CMM was used to digitize point data from physical model. After approximation by rational B-spline curve from digitized point data of a geometric shape, a surface was constructed by the skinning method of the cross-sectional design technique. Since a surface patch was segmented by fifteen part, surface merging was also implemented to assure the surface boundary continuity. Finally, composite surface was transferred to commercial CAD/CAM system through IFES translation in order to machine the modeled geometric shape.

• 만화애니메이션 연구
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• 통권44호
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• pp.33-56
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• 2016

게임 및 영화산업의 급속한 확장에 따라 CG(Computer Graphic)로 구현되는 3D 애니메이션 캐릭터에 대한 연구가 활발히 진행되고 있다. 특히, 삼차원으로 제작되는 캐릭터의 사실적인 움직임을 구현하기 위해서는 뼈와 폴리곤 면을 합쳐주는 리깅(Rigging) 작업과정을 거치게 된다. CG 관련 기술의 급속한 발전에 따라 리깅 작업 과정 또한 보다 정교해지고 있다. 하지만, 기술적인 발전에도 불구하고 여전히 리깅 작업 과정에서 시간적 비효율성, 단순 반복 작업 등의 한계점을 보이고 있다. 본 연구에서는 기존에 사용되는 캐릭터 리깅 방법의 문제점과 비효율성을 분석하고, 보다 효과적인 솔루션을 제안하고자 한다. 이를 위한 연구의 전개는 첫째, 리깅에 대한 일반적 작업과정과 스킨 웨이팅(Skin Weighting)에 대해 기술적 고찰을 하였다. 둘째, 기존 조인트(Joint)만 활용하여 스킨 웨이트(Skin Weight)를 하는 일반적 방법과 여기서 한 단계 발전된 방식으로 다양한 디포머(Deformer)를 활용한 웨이팅 방식을 비교 분석하였다. 셋째, 본 연구에서 제안하는 방법으로써, 디포머인 래티스(Lattice)를 활용하여 웨이팅하고 래티스를 사용한 디포머를 다시 스킨 웨이팅으로 변환하는 방법에 대해 실험연구를 진행한다. 넷째, 기존 방법과 본 연구에서 제안하는 방법에 대해 첫째, 웨이팅을 통해 형성된 지오메트리(Geometry)가 애니메이션의 순차적 움직임에 적절한 형태로 바뀌는지, 둘째, 두 개 이상의 지오메트리가 동시에 효과적으로 웨이팅이 되는지, 셋째, 효율적인 웨이팅 과정을 통한 작업시간의 단축이 이루어지는지를 중심으로 비교 분석하여, 본 연구에서 제시하는 스킨 웨이팅 방법의 효율성에 대해 검증한다. 본 연구를 통해 래티스를 활용한 스킨 웨이팅 작업 진행 결과, 웨이팅 작업과정의 핵심인 페인트 웨이트(Paint weight) 작업이 매우 효율적으로 진행되었으며, 작업시간의 단축 효과와 더불어 작업 결과물의 완성도도 매우 높음을 알 수 있었다. 본 실험연구를 통해 보다 효율적인 캐릭터 스킨 웨이트 방법이 관련 분야 전문가와 학술적 접근에 있어서 기초 자료로 활용되기를 기대한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.567-572
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• 1988

As an efficient way of modeling bodies of complicated shapes, the sweeping and skinning operations have been implemented. These two operations are very powerful modeling method when the body is defined by the cross sections at various locations. For the implementation, the data structure for storing the cross sections and the resulting three dimensional body has been constructed. The resulting object is defined by the boundary representation based on the non-uniform nonperiodic B-spline surface.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.287-292
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• 2002

This paper presents a reverse engineering method for compound surfaces using vision system. A CNC machining center is used as a measuring station, which is equipped with slit beam generator and vision probe. Since obtained data using slit beam or laser scanner may have much data loss along the edge of compound surfaces, an algorithm is presented in this study to recover missing geometric data at such region. First, b-spline interpolation is applied to extract edge information of the surface, and as a next step, b-spline approximation is applied to recover the missing geometric data. Finally, b-spline skinning method is applied to regenerate the surface information. Appropriate simulation and experimental works are preformed to very the effectiveness of the proposed methods.

• Journal of information and communication convergence engineering
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• 제9권3호
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• pp.266-270
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• 2011

The advancement of technology enables smart phones or handheld devices to render complex 3D graphics. However, the processing power and memory of smart phones remain very limited to render high polygon and details 3D models especially on games which requires animation, physic engine, or augmented reality. In this paper, several techniques will be introduced to speed up the computation and reducing the number of vertices of the 3D meshes without losing much detail.

• International Journal of Contents
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• 제3권4호
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• pp.8-14
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• 2007

This study focuses on modeling mobile 3D game engine and suggesting modified skinned-mesh schema based on JSR-184 in order to improve the performance in terms of memory consumption and time complexity. Most of the 3D games have used OpenGL-ES low-level APls, which may limit portability and fast developing time. Hence, the 3D mobile game engine providing high-level APls which works on GSM (Global System for Mobile Communication) phones on J2ME, is proposed here in order to optimize the performance for Java environment abiding JSR-184 standard. To prove performance enhancement, skinned-mesh schema on JSR-184 engine is modified and tested. The experimental results are shown.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2013년도 제48차 하계학술발표논문집 21권2호
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• pp.45-46
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• 2013

대중에게 하나의 취미 생활로 자리매김한 게임은 특징이나 작동 방법에 따라 다양한 장르로 발전되었다. 그 중 액션게임 장르는 사용자가 조작하는 캐릭터의 역동적인 움직임과 움직임이 큰 동작으로 인해 사용자로 하여금 게임 플레이에 몰입할 수 있는 특징을 가지고 있다. 과거 2D 환경의 게임에서 연속되는 그림으로 표현되던 캐릭터의 애니메이션 장면은 3D 환경으로 발전하면서 새로운 애니메이션 기법을 필요로 하였으며, 현재 다양한 애니메이션 기법이 연구되고 있다. 본 논문에서는 3D 뼈대 애니메이션 통하여 DirectX에서의 캐릭터 애니메이션 적용 대해 설명한다.

• Journal of International Society for Simulation Surgery
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• 제2권2호
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• pp.52-57
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• 2015

Virtual Reality makes a virtual environment more realistic and, furthermore, it provides a variety of experiences which we cannot have in reality. A drastic growth of GPU performance and increase of computing capability make virtual environment more realistic than ever. One important element of constructing virtual environment is to animate 3D characters. Many researchers have been studying 3D characters animating and a myriad of methods have been proposed to make them more realistic. In this paper, we discuss the technologies and characteristics of 3D character animation. We believe that realistic characters in Virtual Reality will be applied to various fields: education, film and game industry, business and, particularly, medical area such as telemedicine, virtual surgery, etc.

• 한국CDE학회논문집
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• 제4권1호
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• pp.32-42
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• 1999

Approximate lofting or skinning is one of practical surface modeling techniques well used in CAD and reverse engineering applications. Presented in this paper is a method for approximately lofting a given set of curves wihin a specified tolereance. It is based on refitting input curves simultaneously on a common knot vector and interpolating them to get a resultant NURBS surface. A concept of reducing the number of interior knots of the common knot vector is well adopted to acquire more compact representation for the resultant surface. Energy minimization is newly introduced in curve refitting process to stabilize the solution of the fitting problem and get more fair curve. The proposed approximate lofting provides more smooth surface models and realizes more efficient data reduction expecially when the parameterization and compatibility of input curves are not good enough. The method has been successfully implemented in a new CAD/CAM product VX Vision? of Varimetrix Corporation.