• 제어로봇시스템학회논문지
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• 제21권7호
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• pp.648-653
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• 2015

The kinematics with the instantaneous motion and statics of a manipulator has generally been proven algebraically. The algebraic solutions give very simple and straightforward results but the solutions do not have any meaning in physics or geometry. Therefore it is not easy to extend the algebraic results to design or control a robotic manipulator efficiently. Recently, geometrical approach to define the instantaneous motion or static relation of a manipulator is popularly researched and the results have very strong advantages to have a physical insight in the solution. In this paper, the instantaneous motion and static relation of a planar manipulator are described by geometrical approach, specifically by an axis screw and a line screw. The mass center of a triangle with weight and a perpendicular distance between the two screws are useful geometric measures for geometric analysis. This study provides a geometric interpretation of the kinematics and statics of a planar manipulator, and the method can be applied to design or control procedure from the geometric information in the equations.

• 소성∙가공
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• 제16권7호
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• pp.521-529
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• 2007

This paper is concerned with the analysis on the surface expansion of AA 2024 and AA 1100 aluminum alloys in backward extrusion process. Due to heavy surface expansion appeared usually in the backward can extrusion process, the tribological conditions along the interface between the material and the punch land are very severe. In the present study, the surface expansion is analyzed especially under various process conditions. The main goal of this study is to investigate the influence of degree of reduction in height, geometries of punch nose, friction and hardening characteristics of different aluminum alloys on the material flow and thus on the surface expansion on the working material. Two different materials are selected for investigation as model materials and they are AA 2024 and AA 1100 aluminum alloys. The geometrical parameters employed in analysis include punch corner radius and punch nose angle. The geometry of punch follows basically the recommendation of ICFG and some variations of punch geometry are adopted to obtain quantitative information on the effect of geometrical parameters on material flow. Extensive simulation has been conducted by applying the rigid-plastic finite element method to the backward can extrusion process under different geometrical, material, and interface conditions. The simulation results are summarized in terms of surface expansion at different reduction in height, deformation patterns including pressure distributions along the interface between workpiece and punch, comparison of surface expansion between two model materials, geometrical and interfacial parametric effects on surface expansion, and load-stroke relationships.

• 대한전자공학회논문지SP
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• 제48권4호
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• pp.59-66
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• 2011

본 논문은 영상에서 장면 일루미넌트와 카메라의 위치에 따라 다양한 색과 형태로 나타나는 얼굴을 찾기 위해 색 항등성과 기하학적 분석 기반 검출 기법을 제안한다. 색 항등성 기법을 적용하여 영상에서 장면 일루미넌트의 영향을 제거하고, 기하학적 분석을 통해 다양한 형태로 나타나는 얼굴의 검출한다. 제안한 기법은 색 항등성 기법이 적용된 영상에서 얼굴과 헤어 후보영역을 추출하고, 다양한 기준을 이용하여 후보 영역을 분류한다. 그리고 각 얼굴 후보 영역을 대상으로 헤어 후보 영역과의 교차 영역을 계산하여 얼굴로 판단한다. Caltech Face DB내의 영상들을 이용하여 타 기법과의 성능을 비교하였고, 유색 조명 효과가 부가된 영상들을 대상으로 장면 일루미넌트에 대한 성능을 평가하였다. 실험 결과 제안한 기법은 다양한 입력 영상에서 얼굴 검출이 가능하였고 TP와 낮은 FN 수치로 나타났다.

• 한국초등수학교육학회지
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• 제14권3호
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• pp.701-722
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• 2010

기하를 학습하기 위해 학생들은 일상생활에서 접하는 대상과 다른 구체적 자료를 사용해서 조사하고, 실험하고, 탐구해 보아야 한다. 구체적 조작활동은 수학적 모델링을 하는 과정에서 수학적 개념이나 절차를 이해하게 하고 이것을 기호로 나타내 주는 것을 도와주고 컴퓨터를 활용한 실험활동은 추상적인 학습내용을 시각화하여 직관적, 탐구적 활동에 초점을 둘 수 있게 한다. 따라서 본 연구는 구체물과 탐구형소프트웨어를 활용하여 구체적 조작 실험 활동을 할 수 있는 활동지를 개발하여 평면도형의 성질을 탐구할 수 있는 방안을 제시하고 그 효과를 검증하였다. 구체적 조작 실험의 수업은 중위 수준과 하위 수준의 학생들에게 평면도형의 성질 이해하는데 효과가 있었으며 상위수준 및 하위수준의 학생들에게 수학적 의사소통 능력을 향상시키는데 효과가 있는 것으로 나타났다. 학생들은 조작 실험 활동을 할 때 활동에 필요한 자료의 특성을 먼저 파악해야 하며 학생들에게 활동을 선택하게 할 때 교사의 치밀한 계획과 관찰이 요구된다. 또한 조작활동 후 수학적 의미를 연결짓기 위한 토론 활동이 요구된다.

• 로봇학회논문지
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• 제10권3호
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• pp.146-153
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• 2015

In order to contain as much information as possible in a single image, a wide FOV(Field-Of-View) imaging system is required. The catadioptric imaging system with hyperbolic cylinder mirror can acquire over 180 degree horizontal FOV realtime panorama image by using a conventional camera. Because the hyperbolic cylinder mirror has a curved surface in horizontal axis, the original image acquired from the imaging system has the geometrical distortion, which requires the image processing algorithm for reconstruction. In this paper, the image reconstruction algorithms for two cases are studied: (1) to obtain an image with uniform angular resolution and (2) to obtain horizontally rectilinear image. The image acquisition model of the hyperbolic cylinder mirror imaging system is analyzed by the geometrical optics and the image reconstruction algorithms are proposed based on the image acquisition model. To show the validity of the proposed algorithms, experiments are carried out and presented in this paper. The experimental results show that the reconstructed images have a uniform angular resolution and a rectilinear form in horizontal axis, which are natural to human.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.5-7
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• 1996

We propose a triangulation method based on stereo vision angles. We setup stereo vision systems which extract the depth information to a moving object by detecting a moving object using difference image method and obtaining the depth information by the triangulation method based on stereo vision angles. The feature point of a moving object is used the geometrical center of the moving object, and the proposed vision system has the accuracy of 0.2mm in the range of 400mm.

• 한국복식학회:학술대회논문집
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• 한국복식학회 2003년도 International Costume Conference
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• pp.3-4
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• 2003

The rapid progress of information technology makes the 3rd digital revolution after the 1st agricultural and the 2nd industrial revolution in the human history. The 1st agricultural-oriented society was based on the land and the labor, the 2nd industrial-oriented society was based on the capital and the technology 3rd knowledge-information-oriented society is where to make profit from creative brainworks and ideas based on human beings. The core of the knowledge-information-oriented society is the digital revolution from digitalizing information such as increase of the various digital contents in geometrical progression through internet.

• 호남수학학술지
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• 제28권3호
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• pp.433-438
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• 2006

The Fisher information matrix plays a significant role in statistical inference in connection with estimation and properties of variance of estimators. In this paper, the parameter space of the t-distribution using its Fisher's matrix is defined. The Riemannian and scalar curvatures to parameter space are calculated.

• Fibers and Polymers
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• 제7권4호
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• pp.414-419
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• 2006

The paper presents information concerning metrological and technical characteristics of KTU-Griff-Tester device, the optimization of its parameters and the cases of its application. It was defined that the behaviour of textile material during its extraction through a rounded hole depends upon its structure. Variations of geometrical shape of woven and knitted specimens can be described by mathematical expressions of shortened epicycloids and Cassini ovals. It is shown that waving process of disc shaped specimen can be predicted on the basis of the law of sine curve. The examples of textiles treatment with different types of commercial softeners are presented, herewith showing the suitability (sensitiveness) of the new device to detect the changes of textile hand. Meantime it is shown that the level of materials anisotropy can be decided on the basis of transformations of specimen's geometrical shape.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제9권2호
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• pp.29-43
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• 2005

We consider a surface reconstruction problem from geometrical points (i.e., points given without any order) distributed on a series of smooth parallel cross sections in ${\mathbb{R}}^3$. To solve the problem, we utilize the natural points ordering method in ${\mathbb{R}}^2$, described in [18], which is a method of reconstructing a curve from a set of sample points and is based on the concept of diffusion motions of a small object from one point to the other point. With only the information of the positions of these geometrical points, we construct an acceptable surface consisting of triangular facets using a heuristic algorithm to link a pair of parallel cross-sections constructed via the natural points ordering method. We show numerical simulations for the proposed algorithm with some sets of sample points.