• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1334-1339
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• 2003

An efficient method is developed for the shape optimization of 2-D structures. The sequential linear programming is used for minimization problems. Selected set of master nodes are employed as design variables and assigned to move towards the normal direction. After adapting the nodes on the design boundary, the B-spline curves and mesh smoothing schemes are used to maintain the finite element in good quality. Finally, a numerical implementation of optimum design of an automobile torque converter piston subjected to pressure and centrifugal loads is presented. The results shows additional weight up to 13% may be saved after the shape optimization.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.235-237
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• 2000

본 연구에서는 SRM의 설계 단계에서 일반적으로 얻을 수 있는 자속 쇄교-전류 곡선으로부터 SRM의 토크-속도 특성 곡선을 예측하는 방법을 제시한다. B-스플라인 함수를 이용하여 SRM에 가해질 수 있는 상전류 파형을 모두 모델링하고 각각의 회전자의 속도에서 최대의 토크를 낼 수 있는 전류 파형을 구한다. 제안된 방법은 상전류 제어뿐만 아니라 스위칭 각도 제어까지 고려한 모든 상전류 파형을 표현할 수 있기 때문에 SRM이 최적으로 동작하는 상황에서의 토크-속도 특성임을 보장할 수 있다. 제안된 방법은 SRM의 설계 단계에서 별도의 제어기 설계 없이 간단히 성능을 평가할 수 있는 방법이다.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.119-124
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• 2004

In this study, a rotor blade of a Curtis turbine is investigated. Bezier curve is generally used to define the profile of turbine blades. However, this curve gives a feature of global control, which is not proper to a supersonic impulse turbine blade. Thus, a blade design method is developed by using B-spline curve so that local control is possible to obtain an optimized blade section. To design a Curtis turbine blade section systematically, the blade section has been changed by varying three design parameters using central composite design method. Flow analyses have been carried out for the blade sections, and the effects of design parameters are evaluated.

• The KIPS Transactions:PartB
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• v.13B no.2 s.105
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• pp.187-196
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• 2006

In 3D animation most people adjust the moving motion of their characters on various terrains by using motion data acquired with the motion capture equipment. The motion data can be used to present real human motions naturally, but the data must be captured again to apply to the different terrains from those given at acquiring mode. In addition, there would be a difficulty when applying the data to other characters, in that case the motion data must be captured newly or the existing motion data must be heavily edited manually. In this paper we propose a unified method to generate human motions of walking and running for various terrains such as flat plane, inclined plane, stairway and irregular face. With these methods we are able to generate human motions controlled by the parameters : body height, moving speed, stride, etc. In the proposed methods, the positions and angles of joint can be calculated by using inverse kinematics, and we calculate the trajectory of the swing leg and pelvis according to the cubic spline. With these methods we were presented moving motions using a model of a human body.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.619-622
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• 2003

3차원 모델링 데이터를 VRML로 가시화하기 위해서는 용량 최적화와 실시간 렌더링이 중요하다. 실시간 렌더링은 객체에 따른 폴리건 수에 영향을 받게 되는데, 폴리건 수가 작으면 렌더링의 질이 저하되고 폴리건 수가 많아 데이터 용량이 크면 오브젝트 표현력은 좋으나 높은 대역폭을 필요로 하여, 디더링 철상이 발생과 실시간 렌더링이 어렵게 된다. 그러므로 네트워크 가상공간 내의 오브젝트는 최소의 폴리건을 사용해 메쉬를 단순화 시켜주는 방법으로 데이터 용량을 줄여주는데, 용량은 저하되지만 블록화 현상이 발생하여 저급한 렌더링이 된다. 본 논문에서는 모델링 데이터의 폴리건 수를 줄여 데이터 용량을 최적화 하고, 폴리건의 단순화에서 생기는 블록화 현상을 제거할 수 있는 방법으로 B-스플라인 곡선과 명암처리 기법인 고라우드 명암법을 이용하여 경계면을 부드럽게 처리할 수 있는 기법을 제시한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.663-666
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• 2002

Originally, the thermoforming method has been developed to produce the plastic parts which have simple geometric characteristics such as door trims and wrapping materials within the short time. But the thermoformed parts have non-uniform thickness distributions over the surface according to the material characteristics, set-up angle and geometry of the parts. But, only few analysis methods have been developed so far, due to the difficulties of the selection of important factors, and contribution of each factor in the simulation. So, to guarantee the dimensional accuracy and mechanical properties of crucial points in the thermoformed parts, it is necessary to develop the thickness prediction method. This research suggests a new approaching methodology to predict the thermoformed parts by modulating the control points of the NURBS curve. The newly developed method makes it possible not only to choose the suitable thickness of polymer sheets but also to induce data modification for vacuum forming.

• Journal of Ocean Engineering and Technology
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• v.12 no.3 s.29
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• pp.96-102
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• 1998

This paper presents to create a SAC(Sectional Area Curve) using an ANFIS(Adaptive-Network-based Fuzzy Inference System). First, it defines SACs of parent ships by using a B-spline approximation and a genetic algorithm and accumulates a database about SAC's control points. Second, it learns an ANFIS from parent ship data, which are related with principal dimensions and SAC's control points. This process is to model an ANFIS for SAC inferreice. When an ANFIS modeling is completed, we can determine a SAC through an ANFIS inferring.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.2
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• pp.30-39
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• 2009

Extraction of glomeruli region plays a very important role for diagnosing nephritis automatically. However, it is not easy to extract glomeruli region correctly because the difference between glomeruli region and other region is not obvious, simultaneously unevennesses that is brought in the sampling process and in the imaging process. In this study, a new method for extracting renal glomeruli region using genetic algorithm is proposed. The first, low and high resolution images are obtained by using Laplacian-Gaussian filter with ${\sigma}=2.1$ and ${\sigma}=1.8$, then, binary images by setting the threshold value to zero are obtained. And then border edge is detected from low resolution images, the border of glomeruli is expressed by a closed B-splines' curve line. The parameters that decide the closed curve line with this low resolution image prevent the noises and the border lines from breaking off in the middle by searching using genetic algorithm. Next, in order to obtain more precise border edges of glomeruli, the number of node points is increased and corrected in order from eight to sixteen and thirty two from high resolution images. Finally, the validity of this proposed method is shown to be effective by applying to the real images.

• Journal of Korea Multimedia Society
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• v.12 no.5
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• pp.633-643
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• 2009

We propose a color transfer method that used color contrast based templates to express the visual difference clearly between objects, while remaining the quality of the input image. Our algorithm employs colors of both the input image and template distributed on the $a^{\ast}b^{\ast}$chrominance plane of CIE $L^{\ast}a^{\ast}b^{\ast}$color space. The templates are made by considering the effect of color contrast and have the shape of either a line or a curve represented color distribution of the basic colors based gradation image. These tempates can be modeled on spline curves. We also generate simply new templates with the different basic colors by moving the control points of that curve. The color transfer method using the templates is done through a regressive analysis and color matching. We maintained color coherence of the input image by transforming similarly the color distribution of an input image to the one of templates.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.2
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• pp.101-107
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• 2016

Laser-Assisted machining (LAM) is a new method for processing hard-to-cut materials. However, curved shapes are difficult to predict the preheating effect of by LAM because heat sources are changed by moving laser module. So, it is necessary to study the preheating effect of the laser heat source irradiated on a 3-dimensionally shaped workpiece, such as a NURBS shaped workpiece. In this study, thermal analysis and preheating experiment of the LAM for the NURBS shaped workpiece are performed. Also, two machining methods are proposed to avoid interference of laser module and cutting tool. The results of the analysis can be applied to various shaped workpieces by LAM.