• 대한전자공학회논문지SP
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• 제41권2호
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• pp.41-50
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• 2004

MPEG-4 표준에서는 객체 단위의 부호화를 수행하기 위해 자연영상으로부터 비디오 객체를 분리하는 영상분할(segmentation) 기술이 필요하다. 영상분할 방법은 크게 자동 영상분할(automatic segmentation)과 반자동 영상분할(semi-automatic segmentation)의 두 부류로 나눌 수 있다. 지금까지 개발된 대부분의 자동 영상분할 방법은 비디오 객체의 명확한 수학적인 모델을 제시하기 곤란하며 한 화면에서 개별 객체를 추출하기 어렵기 때문에 그 성능에 한계가 있다. 본 논문에서는 이러한 문제점을 극복하기 위해 active contour 알고리즘을 이용한 반자동 영상분할 알고리즘을 제안한다. 초기 곡선으로부터 변화 가능한 모든 곡선의 집합을 모양공간으로 정의하고 그 공간을 선형공간이라고 가정하면, 모양공간(shape space)은 모양 행렬에 의해 행(column) 공간과 남은 빈(left null) 공간으로 나뉘어진다. 본 논문에서 제안하는 알고리즘은 행공간의 모양공간 벡터를 이용하여 초기 곡선으로부터 영상의 특징점까지의 변화를 기술하고 동적 그래프 검색 알고리즘을 이용하여 객체의 세밀한 부분을 묘사한다. 모양 행렬과 객체의 윤곽을 추정하기 위한 SUSAN 연산자의 사용으로 제안한 알고리즘은 저수준 영상처리로부터 생성되는 불필요한 특징점을 무시할 수 있다. 또한, 모양 행렬의 사용으로 생긴 제약은 동적 그래프 검색 알고리즘으로 보상한다.

• Journal of Advanced Marine Engineering and Technology
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• 제20권1호
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• pp.44-48
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• 1996

In manufacturing of exact products, the offsetting is required to transfer the design data of shape to manufacturing data. In offsetting the degeneracies are occurred, and these problems are mere difficult in freeform shapr manufacuring. This paper is using the geometric properties of B-spline curves to solve the degeneracy of offsetting and to generating of enhanced offsetting. The offsetting of B-spline control polygon spans generates exact control polygon of original shapes. This method is faster in generating offset curve than the normal offsetting, and the resulted offset curves are exact. The additional property of this method is using to control offset shape as B-spline curves. We believe that this method is as effective solution for modifying of offset curves.

• 한국전산유체공학회지
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• 제10권3호
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• pp.27-35
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• 2005

A design optimization of hypersonic flight vehicle has been studied by using upwind Navier-Stokes method and numerical optimization method. CFD method is linked to numerical optimization method by using a Bezier curve and a design optimization of blunt nose hypersonic flight vehicle has been studied. Heat transfer coefficient and drag coefficient are selected as objective functions or design constraints. The Bezier curve-based shape function was applied to blunt body shape.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.169-171
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• 2004

This paper propose a new detection method of curve lane using Catmull-Rom spline for recognition various shape of the curve lane. To improve the accracy of lane detection, binarization and thinning process are firstly performed on the input image. Next, features on the curve lane such as curvature and orientation are extracted, and the control points of Catmull-Rom spline are detected to recognize the curve lane. Finally, Computer simulation results are given using a natural test image to show the efficiency of the proposed scheme.

• Journal of applied mathematics & informatics
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• 제6권3호
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• pp.771-771
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• 1999

• 디지털융복합연구
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• 제11권9호
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• pp.311-318
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• 2013

얼굴 검출 기법들의 경우 조명과 배경에 따라 검출의 정확도가 떨어지는 현상이 발생하여, 이를 해결하기 위한 기법들이 요구되고 있다. 본 연구에서는 얼굴의 눈과 입의 성분을 분석하여 인간의 감성 정보를 추출하기 위한 데이터를 획득하고자 한다. 이를 위해 처리속도가 빠르고 환경 요소들에 강인한 검출율을 보이는 얼굴 특징 검출 방법을 제안하였다. 본 방법은 적분 이미지를 적용한 Haar-like Feature기법을 이용하여 얼굴 성분(두 눈, 입)을 검출한 후, 색상 정보를 바탕으로 검출된 성분들을 이진화하고 피부영역과 얼굴 성분영역을 구분한다. 그 후, 빠르고 정확한 shape를 생성하기 위해 베지어 곡선을 이용하여 검출된 성분들의 shape를 생성한다. 제안된 방법의 성능을 평가하기 위하여 Face Recognition Homepage의 데이터를 이용하여 실험을 진행하였으며, 이를 통해 정교한 얼굴 성분 검출이 가능함을 확인하였다.

• 대한기계학회논문집A
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• 제33권2호
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• pp.99-107
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• 2009

This study produced a design curve and fatigue limit for a variation in volume ratio and reduction ratio of TiNi/Al composites. In many cases, stress-life curve does not indicate fatigue limit, so it was presented by probabilistic-stress-life curve. Goodman diagram was used to analyze the fatigue strength of materials with a finite life determined by repeated load and the fatigue strength of endurance limit with an infinite life. The fatigue experiment was conducted using the scenk-type plane bending specimen in same shape. The result of the fatigue test, which had been conducted under consistent stress amplitude, was examined. (i) The optimal condition for TiNi/Al in accordance with hot pressing (ii) Impacts of fatigue limit caused by a variation in reduction ratio and volume ratio of TiNi/Al composites (iii) Probability distribution for fatigue limit of TiNi/Al2024 and TiNi/Al6061.

• 한국CDE학회논문집
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• 제15권4호
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• pp.253-260
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• 2010

This paper presents algorithms for computing offsets of freeform curves. The approach first divides the original curve into several segments at the inflexion points. Based on the obtained new control polygon and its offsets, quadratic trigonometric splines are constructed to approximate the offset curves. Finally, the shape parameter value of trigonometric spline is determined to satisfy the required tolerance. The degree of the output curve is two, independent of the original curve's degree. Because of the great controllability, the proposed method can generate a completely overestimating offset curve by adjusting the value of the shape parameter, which guarantees no overcutting in NC machining. Furthermore, it also produces the lowest number of control points compared with other works.

• International Journal of CAD/CAM
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• 제12권1호
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• pp.9-19
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• 2012

Generation of optimum planar B-spline curve in terms of minimum deviation and required fairness to approximate a target shape defined by a strip-shaped unorganized 2D point cloud is studied. It is proposed to use the location of control points as variables within the geometric optimization framework of point distance minimization. An adaptive simulated annealing heuristic optimization algorithm is developed to iteratively update an initial approximate curve towards the target shape. The new implementation comprises an adaptive cooling procedure in which the temperature change is adaptively dependent on the objective function evolution. It is shown that the proposed method results in an improved convergence speed when compared to the standard simulated annealing method. A couple of examples are included to show the applicability of the proposed method in the surface model reconstruction directly from point cloud data.

• 한국농공학회지
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• 제45권2호
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• pp.86-95
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• 2003

During this study, constant stress ratio tests with previous compression anisotropic stress history are performed on compacted decomposed granite soil sampled at Iksan, Jeonbuk. Yielding points are determined from stress-strain curves. The shape and characteristics of compression anisotropic yield curves is examined. In addition, the measured value of yielding curve and stress-strain behavior is predicted by Yasufuku's anisotropic constitutive model based on non-associated flow rule. The main results are summarized as follows : 1) Shape of yielding curves shows almost ellipse but asymmetry with respect to stress path during previous consolidation stress. 2) Yasufuku's anisotropic constitutive model is suitable in evaluation of yielding curves on anisotropic consolidated decomposed granite soil. 3) The predicted stress-strain curve shows reasonable agreement to measured behaviours.