• 한국수학사학회지
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• 제16권3호
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• pp.109-114
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• 2003

In this paper, we deal with partially conformal geodesic transformations in Kahler geometry by using Fermi coordinates when tile submanifold is a geodesic sphere. We derive the necessary and sufficient condition for tile existence of such transformation in terms of the Jacobi operator and its derivative.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.917-920
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• 2005

This paper presents 3D graphics geometry processor for mobile applications. Geometry stage needs to cope with the large amount of computation. Geometry stage consists of transformation process and lighting process. To deal with computation in geometry stage, the vector processor that is based on pipeline chaining is proposed. The performance of proposed 3D graphics geometry processor is up to 4.3M vertex/sec at 100 MHz. Also, the designed processor is compliant with OpenGL ES that is widely used for standard API of embedded system. The proposed structure can be efficiently used in 3D graphics accelerator for mobile applications.

• 호남수학학술지
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• 제30권2호
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• pp.207-217
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• 2008

Digital geometry has strongly contributed to the study of a discrete topological space $X{\subset}{\mathbf{Z}}^n$ with k-adjacency of ${\mathbf{Z}}^n$. As a survey-type article, we review various utilities of digital geometry.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.663-666
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• 2005

The geometry stage, which performs the transformation and lighting operations of vertices, became the critical part in 3D graphics pipeline. In this paper, we have planned and designed the Geometry Processor for the better and more efficient way to process the real-time 3D using the floating point unit. We also designed a verification system for Geometry engine. It is implemented with Xilinx-Virtex2 and Visual C++.NET. In the Synopsis, we confirmed 100 MHz performance and 137107 cell area of Geometry Engine.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.915-918
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• 2005

Advances in Information Technology and in Biomedicine have created new uses for CAD technology with many novel and important biomedical applications. Such applications can be found, for example, in the design and modeling of orthopedics, medical implants, and tissue modeling in which CAD can be used to describe the morphology, heterogeneity, and organizational structure of tissue and anatomy. CAD has also played an important role in computer-aided tissue engineering for biomimetic design, analysis, simulation and freeform fabrication of tissue scaffolds and substitutes. And all the applications require precision geometry of the organs or bones of each patient. But the geometry information currently used is polygon model with none solid geometry and is so rough that it cannot be utilized for accurate analysis, simulation and fabrication. Therefore a case study is performed to deduce a transformation method to build free form surface from a rough polygon data or medical images currently used in the application. This paper describes the transformation procedure in detail and the considerations for accurate organ modeling are discussed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.720-724
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• 2004

This paper introduces a new type of driving mechanism for rescue robot that has a variable geometry single-track which satisfies the pre-conditions of rescue robot. This mechanism is a symmetric configuration that has dual directions and prepares against overturn. By using transformation, it can reduce the energy consumption in steering and rotating. And also it maximizes the ability to overcome obstacles, like steps. It is designed to make the size of robot compact and to have the low center of gravity in driving on steps. Finally, we optimized the design variables of components determining the shape of reverse-trapezoid frame to enhance the adaptability to 4 phases of climbing steps.

• 동력기계공학회지
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• 제12권4호
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• pp.18-25
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• 2008

This paper investigated the new calibration algorithm of a straight-type five-hole pressure probe necessary for calculating three-dimensional flow velocity components. The new data reduction method Includes a look-up, a geometry transformation such as the translation and reflection of nodes, and a binary search algorithm. This new calibration map was applied up to the application angle, ${\pm}55^{\circ}$ of a probe. As a result, this data reduction method showed a perfect performance without any kind of interpolation errors In calculating yaw and pitch angle from the calibration map.

• 한국수학사학회지
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• 제29권3호
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• pp.157-172
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• 2016

Sophus Lie's research is regarded as one of the most important mathematical advancements in the $19^{th}$ century. His pioneering research in the field of differential equations resulted in an invaluable consolidation of calculus and group theory. Lie's group theory has been investigated and constantly modified by various mathematicians which resulted in a beautifully abstract yet concrete theory. However Lie's early intentions and ideas are lost in the mists of modern transfiguration. In this paper we explore Lie's early academic years and his object of studies which clarify the ground breaking ideas behind his theory.

• 대한수학회논문집
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• 제36권4호
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• pp.817-827
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• 2021

In this paper, we prove that a diffeomorphism f on a normal almost contact 3-manifold M is a CRL-transformation if and only if M is an α-Sasakian manifold. Moreover, we show that a CR-loxodrome in an α-Sasakian 3-manifold is a pseudo-Hermitian magnetic curve with a strength $q={\tilde{r}}{\eta}({\gamma}^{\prime})=(r+{\alpha}-t){\eta}({\gamma}^{\prime})$ for constant 𝜂(𝛄'). A non-geodesic CR-loxodrome is a non-Legendre slant helix. Next, we prove that let M be an α-Sasakian 3-manifold such that (∇_YS)X = 0 for vector fields Y to be orthogonal to ξ, then the Ricci tensor 𝜌 satisfies 𝜌 = 2α²g. Moreover, using the CRL-transformation $\tilde{\nabla}^t$ we fine the pseudo-Hermitian curvature $\tilde{R}$, the pseudo-Ricci tensor $\tilde{\rho}$ and the torsion tensor field $\tilde{T}^t(\tilde{S}X,Y)$.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제11권2호
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• pp.124-132
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• 2005

본 논문에서는 모바일 장치를 위한 MPEG-4 콘텐츠 저작을 위하여 객체 및 장면 트리 변환을 이용한 방법을 제안한다. 제안하는 방법은 저작시 MPEG-4 콘텐츠의 객체와 장면 트리를 변환하여 모바일 장치에서 재생할 수 있도록 콘텐츠를 재구성한다. 이 방법은 모바일 장치의 작은 인터페이스에서 재생을 효율적으로 할 수 있도록 장면에 표현되는 각 객체를 기하 객체로 변환하고 그 외형을 축소하여 초기 로딩 시간을 감소시키며, 원 객체의 재생은 사용자가 재생 장면에서 해당 기하 객체를 선택할 때 재생된다. 그리고 제안한 방법을 기존 저작 도구에 적용하여, 모바일 장치의 재생기에서 효율적으로 MPEG-4 콘텐츠를 재생시킬 수 있음을 보였다.