• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.1073-1076
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• 1987

In this paper, a new ray tracing algorithm which uses space subdivision method is introduced. In order to reduce huge number of ray-surface intersection calculation, the space is subdivided as lattice that contains minimum number of objects. With lattice structure, the process that calculates unnecessary ray-surface intersection is eliminated.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 추계종합학술대회논문집
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• pp.221-224
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• 2000

We consider one of robust controller, fuzzy-sliding mode controller dealing with model uncertainty, simplified representation of nonlinear system, changed parameters of plant. We propose fuzzy-sliding mode algorithm which provides control input that has system states approaching the choosed sliding surface. This fuzzy controller has a rule base to get initial states converged on sliding surface. This algorithm Is applied to a transfer function of DC motor to be modeled simply and do position control of DC motor due to system parameters. We compare fuzzy-sliding mode controller to both sliding mode controller and fuzzy controller to identify roust control.

• Journal of the Optical Society of Korea
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• 제12권1호
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• pp.13-18
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• 2008

We numerically investigate by the finite-difference time-domain method the effects of surface termination on directional emission exiting a photonic crystal waveguide. The directed power and far-field beam profile for the original proposal [E. Moreno et al., Phys. Rev. B 69, 121402 (2004)] and its enhancement [S. K. Morrison et al., Appl. Phys. Lett. 86, 081110 (2005)] are computed for different values of some important parameters. We find another surface termination condition with a positive surface displacement in the structure of the original proposal which has a negative surface displacement. Our surface termination is more effective than the original structure, and nearly as effective as the termination for the enhancement, for directional emission. Besides, our termination is simpler than that for the enhancement. We confirm the effectiveness of directional emission from our termination in its far-field beam profile, radiation intensity distribution, and additionally the wave-vector space representation by the Fourier analysis.

• 대한기계학회논문집A
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• 제31권1호
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• pp.105-112
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• 2007

The linkage framework of geometric modeling based on NURBS(Non-Uniform Rational B-Spline) surface and shell finite analysis is developed in the present study. For this purpose, geometrically exact shell finite element is implemented. NURBS technology is employed to obtain the exact geometric quantities for the analysis. Especially, because NURBS is the most powerful and wide-spread method to represent general surfaces in the field of computer graphics and CAD(Computer Aided Design) industry, the direct computation of surface geometric quantities from the NURBS surface equation without approximation shows great potential for the integration between geometrically exact shell finite element and geometric modeling in the CAD systems. Some numerical examples are given to verify the performance and accuracy of the developed linkage framework. In additions, trimmed surfaces with some cutouts are considered for more practical applications.

• 한국CDE학회논문집
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• 제15권1호
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• pp.33-42
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• 2010

In this study, new medial surface calculation methods using Voronoi diagrams are investigated for the point samples extracted on closed surface models. The medial surface is defined by the closure of all points having more than one closest point on the shape boundary. It is a one of essential geometric information in 3D and can be used in many areas such as 3D shape analysis, dimension reduction, freeform shape deformation, image processing, computer vision, FEM analysis, etc. In industrial parts, the idealized solid parts and shell shapes including sharp edges and vertices are frequently used. Other medial surface extraction methods using Voronoi diagram have inherent separation and branch problems, so that they are not appropriate to the sharp edged objects and have difficulties to be applied to industrial parts. In addition, the branched surfaces on sharp edges in shell shapes should be eliminated to obtain representative medial shapes. In order to avoid separation and branch problems, the new approach by analyzing the shapes and specially sampling on surfaces has been developed.

• 대한수학회지
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• 제33권4호
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• pp.955-982
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• 1996

In surface compression applications, one of the main issues is how to efficiently store and calculate the computer representation of certain surfaces. This leads us to consider a nonlinear approximation by box splines with free knots since, for instance, the nonlinear method based on wavelet decomposition gives efficient compression and recovery algorithms for such surfaces (cf. [12]).

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.295-302
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• 2001

In the present study, we propose the framework which directly links shell finite element to the surface geometric modeling. For the development of a robust shell element, partial mixed variational functional is provided. The NURBS is used to generate the general free form of parameterized shell surfaces. Employment of NURBS makes shell finite element handle the arbitrary geometry of the smooth shell surfaces. The proposed shell finite element model linked with NURBS surface representation provides efficiency for design and analysis and can be directly extended to surface shape optimization problems in future work.

• 한국전산구조공학회논문집
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• 제15권1호
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• pp.33-42
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• 2002

본 연구에서는 3차원 곡면의 매개변수식 기하 표현법과 계층적/관계형 자료 구조를 이용하여 3차원 터널을 자동으로 모델링할 수 있는 방안을 제시한다. 매개변수식 기하 표현법과 계층적/관계형 자료 구조의 이용은 3차원 터널 표현의 일반화와 확장성을 제공하며 해석을 위한 터널 구조의 특성을 정확하게 처리할 수 있게 한다. 그리고 터널 곡면의 곡률 특징을 이용하여 2차원 요소망 생성 알고리즘을 사용하여 3차원 요소망을 자동으로 생성할 수 있다.

• 로봇학회논문지
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• 제1권2호
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• pp.188-196
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• 2006

During the communication and interaction with a human using motions or gestures, a humanoid robot needs not only to look like a human but also to behave like a human to make sure the meanings of the motions or gestures. Among various human-like behaviors, arm motions of the humanoid robot are essential for the communication with people through motions. In this work, a mathematical representation for characterizing human arm motions is first proposed. The human arm motions are characterized by the elbow elevation angle which is determined using the position and orientation of human hands. That representation is mathematically obtained using an approximation tool, Response Surface Method (RSM). Then a method to generate human-like arm motions in real time using the proposed representation is presented. The proposed method was evaluated to generate human-like arm motions when the humanoid robot was asked to move its arms from a point to another point including the rotation of its hand. The example motion was performed using the KIST humanoid robot, MAHRU.

• 한국가구학회지
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• 제27권1호
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• pp.1-7
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• 2016

De Stijl in order to began in the Netherlands in 1917 is an art movement that becomes the theoretical background of modernism design was the foundation geometric abstraction. Steel design for that they offered a new paradigm at that time art, in various fields such as industrial design is still applied, especially works of De Stijl in the design area of urniture it became the beginning of the modern furniture. The starting point of this study is to analyze the two-dimensional representation characteristics to understand the background of the formation with the basic concepts of De Stijl. Therefore the generation of the surface to be displayed in the work of De Stijl and to analyze the divided element, and not if learn their expression characteristics. Also the line and the plane of the two-dimensional modeling properties of De Stijl, after described colors, and studied the characteristics of De Stjil writers for typical analyzes the moldability shown in their work, which based on, we try to present a new representation technique.