• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.799-804
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• 2003

Friction phenomenon can be described as two parts which are pre-sliding and sliding regions. In motion of the sliding region, friction forces depend on the velocity of the system and are known as Coulomb, stick-slip, stribeck effect and viscous friction. The pre-sliding region, which is before breakaway, depends on the position of the system. The motion of friction in the sliding region can be described as the LuGre model. But the pre-sliding motion of friction, which has hysteresis characteristics in general, is not known widely. Therefore, an improved friction model, which can describe the motion of friction in the pre-sliding region, is proposed in this paper. And simulation and experimental results show the effectiveness of the proposed friction model for precise tracking control systems.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.541-546
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• 2009

There are many videos about sports. There is a large need for content based video retrievals. In sports videos, the motions and camera works have much information about shots and plays. This paper proposes the baseball game process understanding using the similar motion retrieval on videos. We can retrieve the similar motion parts based on motions shown in videos using the space-time images describing the motions. Using a finite state model of plays, we can decide the precise point of pitches from the pattern of estimated typical motions. From only the motions, we can decide the precise point of pitches. This paper describes the method and the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 학술대회 논문집 전문대학교육위원
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• pp.58-61
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• 2001

The purpose of this paper is a fuzzy logic controller for XY positioning system. The overall control system consists of three parts, the position controller, the speed controller, the fuzzy logic controller. Precise tracking is achieved by fuzzy logic controller. In practice, such systems contain many uncertainties. Therefore, the XY positioning system must receive and evaluate the motion of all axis for a better contouring accuracy. Cross coupled controller utilizes all axis position error information simultaneously to produce accurate contours. However, the existing Cross coupled controllers cannot overcome friction, backlash and parameter variation. So, we propose a fuzzy logic controller of XY positioning system. Experimental results show that the proposed fuzzy logic controller is effective to improve the contouring accuracy of XY positioning system.

• 소성∙가공
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• 제9권6호
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• pp.574-581
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• 2000

A vertically-walled auto-body part is one of the most difficult stamping parts because of angle change, wall curl, and twisting of the blank after springback as well as fracture and wrinkle. In this study, computational simulations of the vertically-walled auto-body part are carried out focusing on angle change, wall curl, and twisting after springback. Binderwrap blank shape is used in forming analysis for precise initial contacts between punch and blank. An adaptive mesh method is used in springback analysis for precise calculation of bending moments. In springback analysis, the differences of 2 and 3 dimensional analysis are compared and the effects of blank holdig force and friction coefficient are evaluated. In order to verify the validity of simulation results, they are compared with measured ones. The predicted thickness distribution and formed shape are agreed well with those of the measurement. The Predicted springback amount is less than that of the measurement.

• 한국생산제조학회지
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• 제9권6호
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• pp.152-157
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• 2000

In the control of CNC machine tools, it is significant for precise machining to reduce the contour error. The object of servo-control is reduction of contour error and tracking error. In past studies, there were two approaches to control a servo-system. One was to eliminate axial tracking errors, and the other was to control contour errors. The Cross-coupled controller(CCC) was introduced fro ma veiwpoint of contour error model. Recently, for machining part with free form surfaces, we propose a new contour error model based on curve interpolator. It is presented here that performance of CCC using proposed model is enhanced. Therefore, we can make more precise parts with the curve interpolator and the new contour error model.

• 반도체디스플레이기술학회지
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• 제11권3호
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• pp.39-44
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• 2012

Electronics in modern lives have become more miniaturized and precise. Multi Layered Ceramic Capacitor (MLCC) occupies 50% of electronic components consisting of electronics. This high volume of the production needs high speed and more precise machine performances. The dominate parts of the production equipments are the module transporting components and the visual inspection module. Most visual inspection has been off-line because of the image processing time. In this paper, a new image processing method is proposed to reduce thousands of matrix calculation for image processing and realize on-line high speed inspection.

• 한국산업정보학회논문지
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• 제26권4호
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• pp.19-32
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• 2021

군용 항공기에 대한 모든 정비작업은 항공기 정비매뉴얼의 내용을 기반으로 수행되고 있다. 많은 정비 작업 가운데 특히 부품의 교환작업은 정비작업 가운데에서도 그 비중이 가장 높다. 부품의 교환작업에서는 부품의 형상 파악과 부품간의 체결관계 및 작업절차에 대한 정확한 이해가 대단히 중요하다. 그러나 군은 물론 민간에서 사용되는 정비매뉴얼은 모두 정비작업절차를 간단한 설명과 개략적인 그림으로 표현하고 있어 정확한 작업절차는 물론 부품의 형상을 이해하는데도 어려움이 있다. 반면에 항공기 부품을 3D 모델로 제작한다면 부품을 자유로운 방향에서 관찰할 수 있을 뿐만 아니라 3D 모델링 SW에서만 가능한 강력한 가시화(visualization) 기능을 통해 내부형상이나 체결관계도 쉽게 확인이 가능하다. 특히 정비작업을 3D 애니메이션으로 제작하면 실제와 동일한 순서로 정비작업을 3D 영상으로 관찰할 수 있어 작업절차를 직관적으로 파악하는데 도움이 될 것이다. 이에 본 연구에서는 3D 모델링 SW인 Solidworks를 활용한 3D 정비매뉴얼 개발방법을 제안하고 이에 따라 B747 항공기의 통합구동발전기 교환작업에 대한 3D 정비매뉴얼을 개발하였다. 또 개발된 3D 정비매뉴얼을 기존매뉴얼과 비교하여 그 장단점을 파악하였다. 정비매뉴얼에서 부품 교환에 대한 내용은 기종에 관계없이 비슷하므로 본 연구에서 제안된 방법은 군용항공기용 정비매뉴얼 개발에도 충분히 적용이 가능할 것으로 기대된다.

• 대한수학회지
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• 제40권5호
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• pp.789-830
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• 2003

By forming completions of families of noncommutative polynomials, we define a notion of noncommutative continuous function and locally bounded Borel function that give a noncommutative analogue of the functional calculus for elements of commutative $C^{*}$-algebras and von Neumann algebras. These notions give a precise meaning to $C^{*}$-algebras defined by generator and relations and we show how they relate to many parts of operator and operator algebra theory.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.381-386
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• 2002

In this paper, we have proposed a new approach to the design of robot vision system to develop the technology for the automatic test and assembling of precision mechanical and electronic parts for the factory automation. In order to perform real time implementation of the automatic assembling tasks in the complex processes, we have developed an intelligent control algorithm based-on neural networks control theory to enhance the precise motion control. Implementing of the automatic test tasks has been performed by the real-time vision algorithm based-on TMS320C31 DSPs. It distinguishes correctly the difference between the acceptable and unacceptable defective item through pattern recognition of parts by the developed vision algorithm. Finally, the performance of proposed robot vision system has been illustrated by experiment for the similar model of fifth cell among the twelve cell for automatic test and assembling in S company.

• 한국공작기계학회논문집
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• 제12권3호
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• pp.45-51
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• 2003

Milling process has beer used in aircraft, auto-component and mold industries widely. They need more accurate and precise parts to improve the performance and quality of their products. So, the geometrical form accuracy of the workpiece surface generated by this process is getting more and more important. Generally, the form accuracy is affected by machine conditions, cutting conditions, tool geometry, tool deflection by cutting force and tool path md so on. Even though they are controlled as perfect conditions, it is easily found that there is a line along the axis of a cylindrically milled part. It is presumed that the tool approaching causes this error on milled surface. Thus, the study for investigating the effect of the tool approaching path on the cylindrical surface geometry of the end-milled part is carried out.