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

• KIPS Transactions on Software and Data Engineering
• /
• v.3 no.7
• /
• pp.277-284
• /
• 2014

The detection method of curves for the lanes which is powerful for the variation by utilizing the lane variation vector and cardinal spline on the inverse perspective transformation screen images which do not required the camera parameters are suggested in this paper. This method detects the lane area by setting the expected lane area in the s frame and next s+1 frame where the inverse perspective transformation and entire process of the lane filter are adapted, and expects the points of lane location in the next frames with the lane variation vector calculation from the detected lane areas. The scan area is set from the nextly expected lane position and new lane positions are detected within these areas, and the lane variation vectors are renewed with the detected lane position and the lanes are detected with application of cardinal spline for the control points inside the lane areas. The suggested method is a powerful method for curved lane detection, but it was adopted to the linear lanes too. It showed an excellent lane detection speed of about 20ms in processing a frame.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1991.10a
• /
• pp.96-96
• /
• 1991

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.2
• /
• pp.127-134
• /
• 2009

T-splines are recently proposed geometric modeling tools. A T-spline surface is a NURBS surface with T-junctions and is defined by a control grid called T-mesh. Local refinement can be performed very easily for T-splines while it is limited for B-splines or NURBS. Using T-splines, patches with unmatched boundaries can be combined easily without special technique. In this study, the analysis methodology using T-splines is proposed. In this methodology, T-splines are used both for description of geometries and for approximation of solution spaces. Two-dimensional linear elastic and dynamic problems will be solved by employing the proposed T-spline finite element method, and the effectiveness of the current analysis methodology will be verified.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.12
• /
• pp.75-83
• /
• 2010

Every mechanical part for mass production has dimensions with tolerances in engineering drawing. Tolerance is given to guarantee assemble parts together satisfying functional requirements and dimensional constraints. Tolerance is essential factor for standardization of parts or assembly and has huge influence on manufacturing cost. It will be desirable to have tolerances as broad as possible for minimizing manufacturing cost. This paper describes tolerance analysis of u-joint assembly that is a part of automobile steering system. Within the range of tolerances of parts, accumulated effect is estimated by arithmetic calculation, probability theory and Monte carlo simulation. Each result is compared to investigate the method for increasing productivity.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1994.10a
• /
• pp.866-871
• /
• 1994

B-spline curves and surfaces are effective solutions for design and modelling of the freeform models. The control methods of these are using with control points, knot vectors and weight of NURBS. Using control point is easy and resonable for representation of general models. But the movement of control points bring out the reformation of original convex hull. The B-splines with nonuniform knot vector provide good result of the shape modification without convex hull reforming. B-splines are constructed with control points and basis functions. Nonuniform knot vectors effect on the basis functions. And the blending curves describe the prorities of knot vectors. Applying of these, users will forecast of the reformed curves after modifying controllabler primitives.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.10
• /
• pp.126-131
• /
• 1999

Up until now, it is said that no satisfactory computer solutions have been found for synthesizing four-bar linkage based on the prescribed coupler link curve. In our study, an algorithm has been developed to improve the design synthesis of four-bar linkage automatically generating prescribed path by using B-spline interpolation. The suggested algorithm generates the desired coupler curve by using B-spline interpolation, and hence the generated curve approximates as closely as to the desired curve representing coupler link trajectory. Also, when comparing each generated polygon with the control polygon, rapid comparison by applying convex hull concept. finally, optimization process using ADS is incorporated into the algorithm based on the 5 precision point method to reduce the total optimization process time. As for examples, three different four-bar linkages were tested and the results showed the effectiveness of the algorithm.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.1
• /
• pp.108-115
• /
• 1996

Forging of trapezoidal spline, serration and square spline with solid cylindrical billets and hollow one has been investigated by means of upper bound method. Kinematically admissible velocity fields for forging of splines have been proposed in this study. The half pitch of spline has been divided into several deformation regions. The neutral surface is introduced into forging of splines with flat punch and, for each step, it is assumed as a circle with its radius $r_n$. Upper bound solutions obtained by proposed kinematically admissible velocity fields are useful to predict the loads for forging of splines.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.250-250
• /
• 2004

자동차의 시동을 걸기 위해서는 맨 처음 엔진을 강제로 가동시키는 기계장치가 있어야 하며, 이를 시동모터라 한다. 시동모터는 모터부와 그 부속장치 그리고 발생된 힘을 엔진으로 전달하는 동력전달 기구로 구성되어 있다. 동력전달기구는 플라이 휠이라는 부품을 크랭크 축 끝단에 장착한 후 그 원주상에 링 기어를 만들고, 시동모터의 축에 피니언이라는 작은 기어를 맞물리게 하여 시동 키를 돌리면 이 기어가 회전되는 원리를 이용하고 있다. 피니언 기어는 작고 반대로 플라이 휠에 장착되어 있는 링 기어는 크기 때문에 일정한 기어비가 형성되어 큰 부하의 엔진회전이 가능하다.(중략)

• Proceedings of the Korean Information Science Society Conference
• /
• 2000.10b
• /
• pp.508-510
• /
• 2000

본 논문은 서로 다른 스플라인 곡선들간의 위상적 상호관계로서 곡선과 곡면 설계상에서 중요한 작업인 주어진 영역 안에 한정된 보간곡선 제어방법을 제안한다. 위상적 상호관계는 곡선들간의 영향범위 관계 그리고 스플라인 곡선들과 곡면간의 기하학적 관계를 의미한다. 기존의 방법은 선형 분모를 가지는 분수식 3차 보간법을 사용하여 주어진 영역에서 제한된 보간 곡선을 제어하는 방법을 제안하였으나, 일반적인 경우에서 실행 상의 많은 계산량과 오차가 나타나는 문제점을 나타내었다. 본 논문은 이러한 문제점을 해결하기 위한 선형분모를 가지는 가중치된 분수식 3차 보간법을 제안한다. 이 방법은 변형 보간된 물체상의 변화량을 계산하여 불규칙한 패치들간의 결합부분과 제어 및 국부수정의 변형을 제어하는 방법을 제안한다.