• Journal of the KSME
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• v.34 no.3
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• pp.158-167
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• 1994

제품 기능의 고도화에 부응하여 요구되는 부품의 정밀도가 높아지고, 이러한 부품에 대한 수요가 증가함에 따라 형상 공차에 대한 관심과 활용은 증대되고 있다. 그러나 특히 3차원적 특성을 갖고 있는 원통도와 같은 형상 공차는 그 정의 자체가 내포하고 있는 문제점 및 측정기술의 한 계로 인하여 생상공정과의 직접적인 연결 및 활용에 큰 어려움이 있다. 따라서 원통도의 특성, 가공 형상에 영향을 미치는 인자 및 가공 공정과 가공형상과의 관계를 분석 . 종합한 결과를 기초로 하여 현재의 문제점들에 대처할 수 있는데 기본이 되는 세 가지 가정을 도출하였다. 이 러한 가정들을 이용하여 제안되는 새로운 검사공정은 검사 소요시간, 불량품 검출과 최종제품의 성능 및 신뢰도 확보 측면에서 효과적일 것으로 기대된다. 본문 중에서도 밝힌 바와 같이, 일부 가정은 그 타당성의 근거가 되는 연구 결과가 불충분하여 가능성만을 타진하였다. 따라서 이러한 분야에 대한 연구는 지속적으로 계속되어야 하며, 평면도와 같은 다른 형상공차에 대하여 제시된 방법론의 수정 적용 가능성도 검토되어야 할 것이다.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.2
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• pp.92-99
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• 2004

The errors can cause the serious loss of the performance of a precision machine system. In this paper, we proposed the method of allocating the alignment tolerances of the parts and applied this method to get the optimal tolerances of a Confocal Scanning Microscope. In general, tight tolerances are required to maintain the performance of a system, but a high cost of manufacturing and assembling is required to preserve the tight tolerances. The purpose of allocating the optimal tolerances is minimizing the cost while keeping the high performance of the system. In the optimal problem, we maximized the tolerances while maintaining the performance requirements. The Monte Carlo Method, a statistical simulation method, is used in tolerance analysis. Alignment tolerances of optical components of the confocal scanning microscope are optimized to minimize the cost and to maintain the observation performance of the microscope. We can also apply this method to the other precision machine system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.267-271
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• 2000

A part definition must not only provide shape information of a nominal part but also contain non-shape information such as tolerances, surface roughness and material attributes. Although machining features are useful for suitable shape information for process reasoning in the CAPP, they need to be integrated with tolerance information for effective process planning. We develop the tolerance modeler that efficiently integrates machining features with tolerance information for feature-based CAPP It is based on the association of machining features, tolerance features. and tolerances Tolerance features, where tolerances are assigned, are classified into two types; one is the face that is a topological entity on a solid model and the other is the functional geometry that is not referenced to topological entities. The functional geometry is represented by using machining features All the data for representing tolerance information with machining features are stored completely and unambiguously in the independent tolerance structure. The developed tolerance modeler is implemented as a module of a comprehensive feature-based CAPP system.

• Journal of Korean Society for Quality Management
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• v.42 no.4
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• pp.563-578
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• 2014

Purpose: The purpose of this paper is integrated tolerance design process by advantages of engineering design and 6 sigma statistical tolerances design. Methods: Integrated tolerance design process can determine the goals by using engineer's experience and clarify tolerance by 6 Sigma statistical methods. Integrated design process can be applied by using non-linear simulations. Results: We applied integrated design process to the optical disc drive spindle motor and get good result. Conclusion: If this method is applied test method in the early stages of development, then Design can be reduced development time and cost.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2006.02a
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• pp.1-14
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• 2006

[ $\blacklozenge$ ] PCB에 있어서 Embedded passive 는chip을 직접 내장하는 방법과 특별한 특성을 갖는 재료 및 공법을 사용하여 chip 응 대치하는 방법이 있다. $\blacklozenge$ Embedded passive PCB가 적용될 수 있는 유력한 적용 분야는 소형화가가 요구되는 분야와 고속 특성이 요구되는 분야를 들 수 있고, 따라서, Module, SOP/SIP, Package substrate 등이 우선적으로 적용될 수 있는 분야다. $\blacklozenge$ Embedded capacitor를 적용한 경우, 일반적인 chip capacitor를 적용한 경우보다 더 좋은 전기적인 특성(SRF, Q)을 얻을 수 있으며, solder joint 등의 영향을 포함하면 더욱 좋은 특성이 얻어질 수 있다. $\blacklozenge$ Embedded passive 의 상용화를 위해서, 공차를 관리하는 방법의 개발과 공차에 대한 합리적인 규격을 설정하는 것이 우선 과제이다. $\blacklozenge$ Embedded resistor 의 경우, Laser trim을 적용하여 ${\pm}\;5\%$ 또는 그 이하의 공차를 실현할 수 있고, $30\;K\Omega/sq$. 의 고저항의 적용까지 가능하다. $\blacklozenge$ 고속 신호에서의 noise 감소, module, SIP/SOP 의 소형화를 실현하는데 Embedded passive(혹은 active)PCB 가 기여 할 수 있을 것이고, 이를 위하여 Set 업체, PCB 업체, 재료 업체간의 지속적인 협조가 필요할 것이다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.3
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• pp.452-460
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• 2001

Most of researches of tolerance optimization have used a simple sum of tolerance-cost functions with several constraint equations as an optimization model. However, if there is a machining sequence with more than one processes to complete a part, and machining failure, i.e., out-of-tolerance occurs at one of the intermediate processes, the tolerance-cost of this process should be added by the machining cost of all the previous processes already completed on the part. In this study, an accumulated scrap cost model(ASCM) is proposed considering the scrapped machining cost, and applied to a simple assembly example. The result of tolerance optimization using ASCM is compared with that of using a traditional optimization model to confirm its effectiveness.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1063-1068
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• 2008

A lens system of a camera module for mobile phones is comprised of the composition and design of various shapes of lens. To improve responses such as the modular transfer function (MTF), a lens system should always be constructed by considering uncertainty that can be caused by manufacturing and assembly error. In this study, tolerance optimization using the Latin Hypercube Sampling (LHS) technique is performed. In order to reduce the computational burden of the tolerance optimization process and decrease the influence from numerical noise effectively, we use the Progressive Quadratic Response Surface Modeling (PQRSM), which is one of Sequential Approximate Optimization (SAO) techniques. Using this method, we achieved optimal tolerance for each lens and obtained reliability for satisfying user‘s requirements. In addition, through the design process the manufacturing and assembly cost of a lens system was reduced.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.327-336
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• 1997

This paper addresses an analytical approach to the mechanical error analysis and tolerance design of a four-bar path generator with lubricated joints. The mobility method is applied to consider lubrication effects and the four-bar path generator is stochastically modeled by using the clearance vector model for methanical error analysis. To show the validity of the proposed method, the mechanical errors obtained by applying the method to a four-bar path generator are compared with those by Monte Carlo simulation. Based on this analytical method, an optimal tolerance design problem is formulated and solved for the four-bar path generator.

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

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.78-89
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• 1996

Every mechanical component is fabricated with the variations in its size and shape, and the allowable range of the variation is specified by the tolerance in the design stage. Geometric tolerances specify the size or the thickness of each shape entity itself or its relative position and orientation with respect to datums. Since the range of shape variation can be represented by the variation of the coordinate system attached to the shape, the transformation matrix of the coordinate system would mathematically express the range of shape variation if the interval numbers are inserted for the elements of the transformation matrix. For the shape entity specified by the geometric tolerance with reference to datums, its range of variation can be also derived by propagating the transformation matrices composed of interval numbers. The propagation depends upon the order of precedence of datums.