• The Korean Journal of Applied Statistics
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• v.15 no.1
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• pp.179-186
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• 2002

We usually execute the blocking under heterogeneity of experimental condition in response surface methodology. We can suggest the measure for evaluating nearly orthogonal blocking under second order models.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.101-104
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• 2000

본 논문에서는 곡률 근사화를 이용한 3차원 영상의 표면 분할 알고리즘을 제안한다. 제안한 알고리즘은 기하학적인 접근방법으로 곡률 근사화 이용한 간략화 된 처리 과정의 적용과 곡률의 불연속 정도를 결정하는데 보다 용이한 방법을 제시한다. 이러한 효율적인 에지 검출을 기반으로 여러 가지 3차원 영상의 표면 분할 실험을 통하여 제안한 방법의 성능이 기존의 방법보다 우수함을 확인하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.689-692
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• 2011

본 논문에서는 해양작업 상태의 하중조건을 고려한 부유식 원유생산 저장 하역 장치에 설치된 라이져 보강구조의 강도설계에 관련하여 다양한 근사화 기법 기반 설계 최적화 및 그 성능을 비교하고자 한다. 설계 최적화 문제는 하중조건별 구조강도의 제한조건 하에서 중량을 최소화하여 설계변수인 구조 부재치수가 결정되도록 정식화 된다. 비교 연구를 위해 사용된 근사화 기법은 반응표면법 기반 순차적 근사최적화(RBSAO), 크리깅 기반 순차적 근사최적화(KBSAO), 그리고 개선된 이동최소자승법(MLSM) 기반 근사최적화 기법인 CF-MLSM와 Post-MLSM이다. 본 연구에 적용한 MLSM 기반 근사최적화 기법들은 제한조건의 가용성을 보장할 수 있도록 새롭게 개발되었다. 다양한 근사화 모델 기반 설계 최적화 기법에 의한 결과는 설계 해의 개선 및 수렴속도 등의 수치적 성능을 기준으로 실제 비근사 설계최적화 결과와 비교검토 하였다.

• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1271-1283
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• 2007

To detect defect of FPD(flat panel displays) is very difficult due to uneven illumination on FPD panel image. This paper presents a method to detect various types of defects using the approximated image of the uneven illumination by B-spline. To construct a approximated surface, corresponding to uneven illumination background intensity, while reducing random noises and small defect signal, only the lowest smooth subband is used by wavelet decomposition, resulting in reducing the computation time of taking B-spline approximation and enhancing detection accuracy. The approximated image in lowest LL subband is expanded as the same size as original one by wavelet reconstruction, and the difference between original image and reconstructed one becomes a flat image of compensating the uneven illumination background. A simple binary thresholding is then used to separate the defective regions from the subtracted image. Finally, blob analysis as post-processing is carried out to get rid of false defects. For applying in-line system, the wavelet transform by lifting based fast algorithm is implemented to deal with a huge size data such as film and the processing time is highly reduced.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.543-551
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• 2011

The paper deals with the comparative study of design optimization based on various approximation techniques in strength design of riser support structure installed on floating production storage and offloading unit(FPSO) using offshore operation loading conditions. The design optimization problem is formulated such that structural member sizing variables are determined by minimizing the weight of riser support structure subject to the constraints of structural strength in terms of loading conditions. The approximation techniques used in the comparative study are response surface method based sequential approximate optimization(RBSAO), Kriging based sequential approximate optimization(KBSAO), and the enhanced moving least squares method(MLSM) based approximate optimization such as CF(constraint feasible)-MLSM and Post-MLSM. Commercial process integration and design optimization(PIDO) tools are employed for the applications of RBSAO and KBSAO. The enhanced MLSM based approximate optimization techniques are newly developed to ensure the constraint feasibility. In the context of numerical performances such as design solution and computational cost, the solution results from approximate techniques based design optimization are compared to actual non-approximate design optimization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1880-1893
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• 1994

In this paper, we propose a new shape from shading algorithm which reconstructs object shapes from a single image. In the proposed intative algorithm, given 3D surfaces are approximated by orthogonal polynomials and the relationships between the given surface and its derivatives are constructed ad matrix forms in terms of polynomial coefficients, Also the relative depth and its derivatives are obtained by updating them iteratively. Performance of the propose shape from shading algorithm is evaluated in terms of brightness error, orientation error, and height error, and the performance comparison of the proposed and conventional algorithms is shown.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.10
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• pp.768-776
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• 2006

Given an unstructured point set, we use an MLS (melting least-squares) approximation to estimate the local curvatures and their derivatives at a point by means of an approximation surface Then, we compute neighbor information using a Delaunay tessellation. feature points can then be detected as zero-crossings, and connected using curvature directions. Also this approach has a fast computation time than previous methods, which based on triangle meshes. We demonstrate our method on several large point-sampled models, rendered by point-splatting, on which the feature lines are rendered with line width determined from curvatures.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1992.06a
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• pp.602-606
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• 1992

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.3040-3052
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• 2000

For effective construction of second-order response surface models, an efficient quad ratic approximation method is proposed in the context of trust region model management strategy. In the proposed method, although only the linear and quadratic terms are uniquely determined using 2n+1 design points, the two-factor interaction terms are mathematically updated by normalized quasi-Newton formula. In order to show the numerical performance of the proposed approximation method, a sequential approximate optimizer is developed and solves a typical unconstrained optimization problem having 2, 6, 10, 15, 30 and 50 design variables, a gear reducer system design problem and two dynamic response optimization problems with multiple objectives, five objectives for one and two objectives for the other. Finally, their optimization results are compared with those of the CCD or the 50% over-determined D-optimal design combined with the same trust region sequential approximate optimizer. These comparisons show that the proposed method gives more efficient than others.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.05c
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• pp.495-500
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• 2002

3D 컴퓨터 그래픽스 분야에서 사용되는 표면모델은 일반적으로 매우 복잡하고 방대한 양의 다각형 조각들로 구성된다. 이러한 표면 모델들은 사실감을 높일 수 있지만 지나치게 많은 데이터 양으로 인해 많은 문제들을 야기시킬 수 있다. 따라서 모델의 원래 모양을 가능하면 유지하면서 방대한 양의 데이터를 효과적으로 감소시킬 수 있는 방법이 필요하다. 본 논문에서는 지역표면의 기하학적 특성을 잘 보존할 수 있는 에지 비용함수를 제안한다. 또한 병합에 기반 한 반복적인 에지 축약을 기본 연산으로 하는 표면 간략화 알고리즘을 구현한다. 병합에 기반 한 축약방법은 메모리를 효율적으로 사용할 수 있게 하여 실시간 데이터 전송을 요하는 응용 시스템에 매우 효과적으로 적용될 수 있다. 제안하는 알고리즘을 표면모델에 적용시켜 간략화를 수행 한 결과 기존의 알고리즘에 비해 높은 품질의 근사모델을 얻을 수 있었으며 원래 모델의 세부적인 모양을 잘 보존할 수 있었다.