• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1997년도 추계학술대회 학술발표 논문집
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• pp.435-438
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• 1997

This paper presents the process generating a SAC(Sectional Area Cure) by using ASMOD(Adaptive Spline Modeling of Observation Data). That is, we define SACs of real ships as B-spline curves by a hybrid cure approximation(which is the combination method of a B-spline fitting method and a genetic algorithm) and accumulate a database of control points. Then we let ASMOD learn from the correlation principal dimensions with control points.

• Journal of the Korean Data and Information Science Society
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• 제9권1호
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• pp.77-88
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• 1998

Smoothing spline estimators are modified to remove boundary bias effects using the technique proposed in Eubank and Speckman (1991). An O(n) algorithm is developed for the computation of the resulting estimator as well as associated generalized cross-validation criteria, etc. The asymptotic properties of the estimator are studied for the case of a linear smoothing spline and the upper bound for the average mean squared error of the estimator given in Eubank and Speckman (1991) is shown to be asymptotically sharp in this case.

• 한국CDE학회논문집
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• 제17권4호
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• pp.282-293
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• 2012

This paper presents an error-bounded B-spline fitting technique to approximate unorganized data within a prescribed error tolerance. The proposed approach includes two main steps: leastsquares minimization and error-bounded approximation. A B-spline hypervolume is first described as a data representation model, which includes its mathematical definition and the data structure for implementation. Then we present the least-squares minimization technique for the generation of an approximate B-spline model from the given data set, which provides a unique solution to the problem: overdetermined, underdetermined, or ill-conditioned problem. We also explain an algorithm for the error-bounded approximation which recursively refines the initial base model obtained from the least-squares minimization until the Euclidean distance between the model and the given data is within the given error tolerance. The proposed approach is demonstrated with some examples to show its usefulness and a good possibility for various applications.

• International Journal of Precision Engineering and Manufacturing
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• 제6권1호
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• pp.15-22
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• 2005

This research presents modeling of a functional surface that is constructed with a free-formed surface. The modeling of functional surfaces, being introduced in this paper, adopts a modified B-spline that utilizes an approximating technique. The modified B-Spline is constructed with altered control vertices. It is applied to measure the surface of an impeller blade. This research builds an algorithm accepting inputs of measured points. Generating the cutter-paths for NC machining employs the model of the constructed surfaces. The machined surfaces that are generated in several cases are compared with each other in the aspect of machining accuracy.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.381-386
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• 2001

When a input image is extensively magnified on the computer system, it is almost impossible to replicate the original shape because of mismatched coordinates system. In order to resolve the problem, the shape of the magnified image has been reconfigured using the bilinear interpolation method, low pass special filtering interpolation method and B-spline interpolation method, Ferguson curve interpolation method based on the CAD/CAM curve interpolation algorithm. The computer simulation main result was that. Nearest neighbor interpolation method is simple in making the interpolation program but it is not capable to distinguish the original shape. Bilinear interpolation method has the merit to make the magnified shape smooth and soft but calculation time is longer than the other method. Low pass spatial filtering method and B-spline interpolation method has an effect to immerge the intense of the magnified shape but it is also difficult to distinguish the original shape. Ferguson curve interpolation method has sharping shape than B-spline interpolation method.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권8호
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• pp.469-476
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• 2004

In this paper, a 3D shape optimization algorithm which guarantees a smooth optimal shape is presented using parameterized sensitivity analysis. The design surface is parameterized using Bezier spline and B-spline, and the control points of the spline are taken as the design variables. The parameterized sensitivity for the control points are found from that for nodal points. The design sensitivity and adjoint variable formulae are also derived for the 3D non-linear problems. Through an application to the shape optimization of 3D electromagnet to get a uniform magnetic field, the effectiveness of the proposed algorithm is shown.

• 한국게임학회 논문지
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• 제11권1호
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• pp.93-100
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• 2011

현대 게임 개발에 있어서 영화에서 쓰이는 카메라 연출 기법을 이용하여 게임을 제작하는 사례가 많아지고 있다. 본 논문에서는 게임 제작시 3차원 공간상에 곡선을 이용하여 오브젝트의 이동 및 카메라 연출 기법에 대해 논의한다. Catmull-Rom 곡선은 다른 곡선들에 비하여 정확히 곡선 위를 따라가는 알고리즘이다. 본 연구에서는 3차원 공간상에서 Catmull-Rom 곡선을 이용하여 다 구간에 대해 사용자의 입력에 따라 동적으로 생성하여 오브젝트가 자연스럽게 경로 위를 지나갈 수 있는 알고리즘을 제시한다. 또한, Catmull-Rom 곡선을 이용하여 커씬 구간을 설정하여 오브젝트가 이동하는 것을 관찰 할 수 있는 기법에 대해 소개한다. 실험으로는 곡선의 정확성 및 효율성에 대해 실험하였고 Catmull-Rom 곡선이 오브젝트의 이동 뿐만 아니라 카메라 연출 기법에서도 매우 효율적이라는 것을 알 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제36권5호
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• pp.211-220
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• 2015

Recently, model-based iterative reconstruction (MBIR) has played an important role in transmission tomography by significantly improving the quality of reconstructed images for low-dose scans. MBIR is based on the penalized-likelihood (PL) approach, where the penalty term (also known as the regularizer) stabilizes the unstable likelihood term, thereby suppressing the noise. In this work we further improve MBIR by using a more expressive regularizer which can restore the underlying image more accurately. Here we used a spline regularizer derived from a linear combination of the two-dimensional splines with first- and second-order spatial derivatives and applied it to a non-quadratic convex penalty function. To derive a PL algorithm with the spline regularizer, we used a separable paraboloidal surrogates algorithm for convex optimization. The experimental results demonstrate that our regularization method improves reconstruction accuracy in terms of both regional percentage error and contrast recovery coefficient by restoring smooth edges as well as sharp edges more accurately.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제10권1호
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• pp.31-45
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• 2006

최근 고집적화, 고밀도화 되어가는 첨단 디바이스와 섬세한 공정들은 SMT(surface mounting technology)에서의 더욱 까다로운 검사 항목들을 요구하고 있다. 특히, 어셈블리 생산품의 불량의 60% 이상을 차지하는 솔더 프린팅의 검사는 이러한 추세에 대응책으로 3차원적인 검사방식이 기존의 2차원적인 검사방식을 빠르게 대치해나가고 있다. 따라서 본 논문에서는 SMT 어셈블리 라인에서 PCB(Printed circuit board)에 프린팅된 솔더 페이스트에 대한 3차원적인 검사를 자동으로 수행하는 인라인형의 고속 3차원 검사 장비 및 측정 알고리즘을 제안한다. 제안한 방법은 3차원 데이터를 B-스플라인으로 표면을 구성한 다음 이를 기반으로 패드를 추출하고, 검사하는 알고리즘이다.

• 대한조선학회논문집
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• 제34권4호
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• pp.127-138
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• 1997

본 연구에서는 선박의 기본설계 단계에서 정의된 선도를 입력 정보로 하여 순정도 높은 선형을 표현할 수 있는 기법을 개발하였다. 곡선모델링의 경우, de Casteljau (드 카스텔죠)알고리듬과 Bezier 조정점을 이용하여 자유곡선을 표현하였고, 이를 토대로 Non-Uniform B-Spline(NUB) 곡선, Spline곡선 등으로 서로 변환(Conversion)할 수 있는 Unified curve modeling( 곡선모델링 단일화) 기법을 정립하였다. 곡면모델링의 경우, 곡면정의를 위하여 입력되는 그물망 곡선(Mesh curve net)을 먼저 Unified curve modeling 기법에 의하여 Interpolation(보간)한 후, "Remeshing" (그물망 곡선의 재생성)기법에 의하여 Gregory surface patch(그레고리 곡면 patch)의 Mesh curve segment(경계 세그멘트 곡선)를 생성하고 이를 접속하여 순정도 높은 Composite surface(합성곡면)를 만드는 기법을 개발하였다.