• Structural Engineering and Mechanics
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• 제12권3호
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• pp.313-328
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• 2001

A multi-span bridge has the peak value of resultant girder moment or membrane stress at the interior support. In this paper, the spline finite strip method (FSM) is modified to obtain the more appropriate solution at the interior support where the peak values of solution exist. The modification has been achieved by expressing the shape function with non-periodic B-splines which have multiple knots at the boundary. The modified B-splines have the useful feature for interpolating the curve with sudden change in curvature. Moreover, the modified spline FSM is very efficient in analyzing multi-span box girder bridges, since a bridge can be modeled by an assembly of strips extended along the entire bridge length. Numerical examples of the bridge analysis have been performed to verify the efficiency and accuracy of the new spline FSM.

• 전기학회논문지
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• 제63권1호
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• pp.92-98
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• 2014

This paper proposes a hermite spline based D* algorithm for effective path planning of mobile robot to improve the detecting speed. In conventional path planning research, a robot is supposed to pass through predetermined centers of grid partitions of area. However it doesn't guarantee the optimal path during its navigation. In addition, a robot is hard to avoid obstacles effectively. The proposed algorithm in this paper makes use of stochastic characteristics of nonholonomic mobile robot and estimation of shortest path to curvature movement of the robot. The performance evaluation of the improved spline D* algorithm performed through simulation shows its effectiveness. Moreover, the experiment verifies that a robot can find the shortest path by building the curve paths while it is moving on the path in spline.

• ETRI Journal
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• 제39권4호
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• pp.493-501
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• 2017

This paper introduces a new motion-synthesis technique for animating multiple characters. At a high level, we introduce a hub-sub-control-point scheme that automatically generates many different spline curves from a user scribble. Then, each spline curve becomes a trajectory along which a 3D character moves. Based on the given curves, our algorithm synthesizes motions using a cyclic motion. In this process, space-time warp curves, which are time-warp curves, are embedded in the 3D environment to control the speed of the motions. Since the space-time warp curve represents a trajectory over the time domain, it enables us to verify whether the trajectory causes any collisions between characters by simply checking whether two space-time warp curves intersect. In addition, it is possible to edit space-time warp curves at run time to change the speed of the characters. We use several experiments to demonstrate that the proposed algorithm can efficiently synthesize a group of character motions. Our method creates collision-avoiding trajectories ten times faster than those created manually.

• 품질경영학회지
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• 제32권4호
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• pp.265-273
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• 2004

We got the growth distance curve by spline smoothing method with observed marketing data and the growth velocity curve by the derivation of the growth distance curve. Using this growth velocity curve, we defined the several characteristic points which describe the variation of marketing data. In this paper, to specify several patterns of marketing data, we suggested characteristic function by using these characteristic points. In addition, we applied characteristic function to the seventeen brands of electric home products data.

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

• 소성∙가공
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• 제13권1호
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• pp.33-38
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• 2004

A new approach for the design of extrusion die surface of arbitrarily shaped section is presented. In order to generate the extrusion die surface. an automatic surface construction method based on B-spline surface and scalar field theory is proposed. The isothermal lines and stream lines designed in the scalar field are introduced to find the control points which are used in constructing B-spline surfaces. Intersected points between the isothermal lines and stream lines are used to construct B-spline surfaces. The inlet and outlet profiles are precisely described with B-spline curves by using the centripetal method for uniform parameterization. The extrusion die surface is generated by using the cubic curve interpolation in the u- and v-directions. A quantitative measure for the control of surface is suggested by introducing the tangential vectors at the inlet and outlet sections. To verify the validity and effectiveness of the proposed method, automatic surface generation is carried out for extrusion dies of arbitrarily shaped sections.

• 대한기계학회논문집A
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• 제33권2호
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• pp.135-144
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• 2009

In this present work, spline FEA for the trimmed NURBS surface of the 2D linear elasticity problem is presented. The main benefit of the proposed method is that no additional efforts for modeling of trimmed NURBS surfaces are needed and the information of the trimming curves and trimmed surfaces exported from the CAD system can be directly used for analysis. For this, trimmed elements are searched by using NURBS projection scheme. The integration of the trimmed elements is performed by using the NURBS-enhanced integration scheme. The formulation of constructing stiffness matrix of trimmed elements is presented. In this formulation, the information of the trimming curve is used for calculating the Jacobian as well as for obtaining integration points. The robustness and effectiveness of the proposed method are investigated through various numerical examples.

• 한국컴퓨터그래픽스학회논문지
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• 제22권5호
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• pp.1-16
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• 2016

본 논문에서는 최소자승법에 기반한 효율적인 곡선 복구 기법을 제안한다. 구체적으로는, 법선 벡터를 포함한 평면상의 샘플포인트가 주어졌을 때 계층적인 ZP(Zwart-Powell)-스플라인의 레벨로 곡선을 복구하는데, 세밀한 부문을 복구하면서도 비교적 큰 구멍도 효율적으로 메꾸고 있다. 정규화를 위해서는, (1) 선형시스템의 특이성을 피하기 위한 티코노프 정규항과 (2) 아이소커브를 부드럽게 하기 위한 이산 라플라스 정규항 두 가지를 사용하고 있다. 정량적인 벤치마크 테스트를 통해 비교한 결과, 본 방법은 다항식에 기반한 기법들에 비해 훨씬 우수한 결과를 보여준다는 것을 확인할 수 있다. 구멍이 있는 데이터의 경우, 계층적인 B-스플라인과 비교해본 결과 엇비슷한 품질을 보이지만 약 90%의 계산량만을 필요로 한다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.115-124
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• 2005

This paper analyzes the problems that occurred in the magnification process for a fine input image and investigates a method to improve the problems. This paper applies a curve interpolation algorithm in CAD/CAM for the same test images with the existing image algorithm in order to improve the problems. As a result. the nearest neighbor interpolation. which is the most frequently applied algorithm for the existing image interpolation algorithm. shows that the identification of a magnified image is not possible. Therefore. this study examines an interpolation of gray-level data by applying a low-pass spatial filter and verifies that a bilinear interpolation presents a lack of property that accentuates the boundary of the image where the image is largely changed. The periodic B-spline interpolation algorithm used for curve interpolation in CAD/CAM can remove the blurring but shows a problem of obscuration, and the Ferguson's curve interpolation algorithm shows a more sharpened image than that of the periodic B-spline algorithm. For the future study, hereafter. this study will develop an interpolation algorithm that has an excel lent improvement for the boundary of the image and continuous and flexible property by using the NURBS. Ferguson's complex surface. and Bezier surface used in CAD/CAM engineering based on. the results of this study.

• 한국CDE학회논문집
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• 제13권6호
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• pp.440-449
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• 2008

This paper deals with a method calculating various hull form parameters which are required in numerical analysis for ship performance such as motion, maneuverability, resistance and propulsion, etc. After the hull form is designed, before the model tests the ship's performances are evaluated by various analysis tools in which the hull form parameters are used with many kinds of forms aside from offset data. Here, The hull form parameters characterize the properties of hull form and contain positional, differential and integral information implicitly. Generally, the commercial CAD-system has not functions enough for supporting these form parameters and therefore each shipyard uses its own in-house analysis program as well as commercial analysis software. To overcome these limitations, modules for supporting these analysis programs have developed. The modules contain cubic composite spline cure using local curve fairing, intersect algorithm, Gaussian integral, and other geometric techniques needed in calculating hull form parameters. Using our analysis-supporting modules, a complex hull form can be remodeled exactly to the hull form designed by CAD-system and any hull form parameter required in various performance analyses can be calculated.