• 한국정밀공학회지
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• 제23권2호
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• pp.35-42
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• 2006

Although the conventional contour parallel tool path obtained from geometric information has been successful to make desirable shape, it seldom consider physical process concerns like cutting forces and chatters. In this paper, an optimized contour parallel path, which maintains constant MRR(material removal rates) at all time, is introduced and the result is verified. The optimized tool path is based on a conventional contour parallel tool path. Additional tool path segments are appended to the basic tool path in order to achieve constant cutting forces and to avoid chatter vibrations at the entire machining area. The algorithm has been implemented for two dimensional contiguous end milling operations with flat end mills, and cutting tests were conducted to verify the significance of the proposed method.

• 한국통신학회논문지
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• 제24권12B호
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• pp.2359-2368
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• 1999

본 논문에서는 2차원 영상을 기반으로 3차원 목표물을 인식하는 기법의 한 예로서 적외선 영상으로부터 추출된 물체의 모양 정보와 모양 정보의 신뢰도를 이용해서 지상에서 지상용 차량을 인식하는 기법(ground-to-ground vehicle recognition)을 제안한다. 우선 목표물 추출과정에서 얻어진 마스크의 윤곽선 상에 있는 점들 중 에지 경사도의 크기와 밝기값이 일정한 값 이상이 되는 점들을 신뢰도가 높은 점이라고 정의하고 신뢰도가 높은 점들을 연결해서 신뢰도가 높은 부분 윤곽선(sub-contour)을 추출한다. 모델로부터 입력 영상의 신뢰도가 높은 윤곽선에 해당되는 윤곽선을 선택한 후 각각 해당되는 윤곽선들은 이산 정현 변환(Discrete Sine Transform)을 사용해서 특징값을 계산한 다음 서로 비교한다. 실험 결과 영상 분할이 불완전한 경우 신뢰도를 이용한 방법이 그렇지 않은 방법보다 더 나은 결과를 보였다.

• International Journal of CAD/CAM
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• 제8권1호
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• pp.21-28
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• 2009

In the present work, an attempt has been made to construct branching surface from 2-D contours, which are given at different layers and may have branches. If a layer having more than one contour and corresponds to contour at adjacent layers, then it is termed as branching problem and approximated by adding additional points in between the layers. Firstly, the branching problem is converted to single contour case in which there is no branching at any layer and the final branching surface is obtained by skinning. Contours are constructed from the given input points at different layers by energy-based B-Spline approximation. 3-D curves are constructed after adding additional points into the contour points for all the layers having branching problem by using energy-based B-Spline formulation. Final 3-D surface is obtained by skinning 3-D curves and 2-D contours. There are three types of branching problems: (a) One-to-one, (b) One-to-many and (c) Many-to-many. Oneto-one problem has been done by plethora of researchers based on minimizations of twist and curvature and different tiling techniques. One-to-many problem is the one in which at least one plane must have more than one contour and have correspondence with the contour at adjacent layers. Many-to-many problem is stated as m contours at i-th layer and n contours at (i+1)th layer. This problem can be solved by combining one-to-many branching methodology. Branching problem is very important in CAD, medical imaging and geographical information system(GIS).

• 대한의용생체공학회:의공학회지
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• 제13권2호
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• pp.115-124
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• 1992

An algorithm has been proposed for the automatic detection of optimal epiand endocardial left ventricular borders from 2-D short axis echocardiogram which is degraded by noise and echo drop out. For the implementation of the algorithm, we modified Ballard's Generalized Hough Transform which can be applicable only for deterministic object border, and newly proposed Fuzzy Hough Transform method. The algorithm presented here allows detection of object whose exact shapes are unknown. The algorithm only requires an approximate model of target object based on anatomical data. To detect the approximate epicardial contour of left ventricle, Fuzzy Hough Transform was applied to the echocardiogram. The optimal epicardial contour was founded by using graph searching method which contains cost function analysis process. Using this optimal epicardial contour and average thickness imformation of left ventricular wall, the approximate endocardial line was founded, and graph searching method was also used to detect optimal endocardial contour.

• Journal of International Society for Simulation Surgery
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• 제2권1호
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• pp.17-25
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• 2015

Purpose In this paper, we propose a robust 3D vessel tracking algorithm by utilizing an active contour model and unscented Kalman filter which are the two representative algorithms on segmentation and tracking. Materials and Methods The proposed algorithm firstly accepts user input to produce an initial estimate of vessel boundary segmentation. On each Computed Tomography Angiography (CTA) slice, the active contour is applied to segment the vessel boundary. After that, the estimation process of the unscented Kalman filter is applied to track the vessel boundary of the current slice to estimate the inter-slice vessel position translation and shape deformation. Finally both active contour and unscented Kalman filter are inter-operated for vessel segmentation of the next slice. Results The arbitrarily shaped blood vessel boundary on each slice is segmented by using the active contour model, and the Kalman filter is employed to track the translation and shape deformation between CTA slices. The proposed algorithm is applied to the 3D visualization of chest CTA images using graphics hardware. Conclusion Through this algorithm, more opportunities, giving quick and brief diagnosis, could be provided for the radiologist before detailed diagnosis using 2D CTA slices, Also, for the surgeon, the algorithm could be used for surgical planning, simulation, navigation and rehearsal, and is expected to be applied to highly valuable applications for more accurate 3D vessel tracking and rendering.

• 한국정밀공학회지
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• 제10권4호
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• pp.81-93
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• 1993

The three dimensional(3D) shape reconstruction from two dimensional(2D) cross-sections can be completed through three main phases : the input compilation, the triangular grid formation, and the smooth surface construction. In the input compilation phase, the cross-sections are analyzed to exctract the input data required for the shape reconstruction. This data includes the number of polygonized contours per cross-section and the vertices defining each polygonized contour. In the triangular grid formation phase, a triangular grid, leading to a polyhedral approximations, is constructed by extracting all the information concerning contour links between two adjacent cross- sections and then performing the appropriate triangulation procedure for each contour link. In the smooth surface construction phase, a smooth composite surface interpolating all vertices on the triangular grid is constructed. Both the smooth surface and the polyhedral approximation can be used as reconstructed models of the object. This paper proposes a new method for reconstructing the geometric model of a 3D objdect from a sequence of planar contours representing 2D cross-sections of the objdect. The method includes the triangular grid formation algorithms for contour closing, one-to-one branching, and one-to-many braanching, and many-to-many branching. The shape reconstruction method has been implemented on a SUN workstation in C.

• 한국의학물리학회지:의학물리
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• 제7권2호
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• pp.79-90
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• 1996

본 논문에서는 2 차원 심초음파도의 경계선 유사 영역에 대해 베이즈 추정기를 사용하여 경계선 검출을 위한 자동문턱 결정방법을 제안하고자 한다. 경계선 유사영역은 전처리과 정에서 흐려진 영상을 명확히 하는데 사용할 열비등방성 확산 방법의 전도계수로부터 얻어진다, 이러한 경계선 유사 영역에 대해 최적 문턱치를 선택하기 위해 베이즈 추정기가 사용되었다. 이 문턱치를 사용하여 영상을 이진화함으로서 심초음파도의 경계선을 자동 적으로 검출하게 된다. 마지막으로 본래의 심초음파도에 위에서 얻어진 경계선을 덧씌움으로써 경계선이 강조된 심초음파도를 얻을 수 있게 된다.

• International Journal of Precision Engineering and Manufacturing
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• 제8권1호
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• pp.16-20
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• 2007

Although conventional contour parallel tool paths obtained from geometric information have successfully been used to produce desired shapes, they seldom consider physical process concerns such as cutting forces and chatter. In this paper, we introduce an optimized contour parallel path that maintains a constant material removal rate at all times. The optimized tool path is based on a conventional contour parallel tool path. Additional tool path segments are appended to the basic path to achieve constant cutting forces and to avoid chatter vibrations over the entire machining area. The algorithm was implemented for two-dimensional contiguous end milling operations with flat end mills, and cutting tests were conducted to verify the performance of the proposed method.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.554-559
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• 1999

The purpose of this study is the machining of texture shapes by the contour fitting data. The hardware of the system comprises PC and scanning system, CO2 laser machine. There are four steps, (1) text image loading using scanning shapes or 2D image files, (2) generation of contour fitting data by the line and arc, cubic Bezier curve, (3) generation of NC code from the contouring fitting data, (4) machining by the DNC system. It is developed a software package, with which can conduct a micro CAM system of CNC laser machine in the PC without economical burden.

• Journal of Information Processing Systems
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• 제18권2호
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• pp.223-234
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• 2022

The evaluation of the print quality of 3D printing has traditionally relied on manual work using dimensional measurements. However, the dimensional measurement method has an error value that depends on the person who measures it. Therefore, we propose the design of a new print quality measurement method that can be automatically measured using the field-of-view (FOV) model and the intersection over union (IoU) technique. First, the height information of the modeling is acquired from a camera; the output is measured by a sensor; and the images of the top and isometric views are acquired from the FOV model. The height information calculates the height ratio by calculating the percentage of modeling and output, and compares the 2D contour of the object on the image using the FOV model. The contour of the object is obtained from the image for 2D contour comparison and the IoU is calculated by comparing the areas of the contour regions. The accuracy of the automated measurement technique for determining, which derives the print quality value was calculated by averaging the IoU value corrected by the measurement error and the height ratio value.