• 대한안전경영과학회지
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• 제3권3호
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• pp.221-230
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• 2001

The assembly tolerance design methods have applied linear or nonlinear programming methods and used simulation method and search algorithms to optimize the tolerance allocation of each part in an assembly. However, those methods are only considered to the relationship between tolerance and manufacturing cost, which do not consider a quality loss cost for each part tolerance. In this paper, the integrated simulation model used genetic algorithm and the Monte-Carlo simulation method was developed for the allocation of the optimal tolerance considering the manufacturing cost and quality loss cost.

• 산업경영시스템학회지
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• 제22권49호
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• pp.33-41
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• 1999

The original tolerances, which are assigned by designers on the basis of handbooks and experience, cannot always be expected to be optimal or feasible, because they may yield an unacceptable manufacturing costs. So the systematic tolerance design considering manufacturing costs should be done. Therefore, this research analyzes the tolerance within the tolerance design using Monte-Carlo simulation method and sensitivity analysis and using genetic algorithm by tolerance allocation method. The genetic algorithm was developed for allocation of the optimal tolerance under the manufacturing limitation cost.

• 대한기계학회논문집A
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• 제22권1호
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• pp.215-226
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• 1998

This paper addresses an analytical approach to tolerance and reliability analysis of mechanical systems with uncertainty. Many mechanical systems consist of links and lubricated joints. The mobility method is applied to consider lubrication effects and the clearance vector model is used to stochastically define a mechanism for tolerance and reliability analysis. To show the validity of the proposed method, a four-bar path generator and a slider-crank mechanism are considered. The results obtained by applying the proposed method are compared with those by Monte-Carlo simulation.

• 한국생산제조학회지
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• 제9권1호
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• pp.45-52
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• 2000

The purpose of this research was developing an integrated way to solve two typical tolerance optimization problem i.e. optimal tolerance allotment and design centering. A new problem definition design centering-tolerance allotment problem (DCTA) was proposed here for the first time and solved. Genetic algorithm and coarse Monte Carlo simulation were used to solve the stochastic optimization problem. Optimal costs were compared with the costs from the previous optimization strategies Significant cost reductions were achieved by DCTA scheme.

• 대한안전경영과학회지
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• 제7권2호
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• pp.73-83
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• 2005

This paper is to propose tolerance intervals for expected time at the given reliability and confidence level for continuous and discrete reliability model. We consider guaranteed - coverage tolerance intervals, that is, reliability - confidence level tolerance intervals. These proposed methodologies can be applied to any industrial application where the customer's operating specification require a high level of reliability.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.995-999
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• 1995

In spindle-bearing system, the displacement characteristics of the bearing by the load applied on the spindle are affected greatly by the assembling tolerance between the spindle and housing assembled to support the bearing. Also in spindle system of rotational operation, the compliance characteristic of the bearing is expected to be varied frequently by the thermal deformation of the spindle and the housing. To predict the thermal deformation of the spindle including heat generation of the bearing, we need to examine the effect on the compliance of spindle-bearing system by the assembling tolerance. In this paper, we proposed the load-displacement relation expression considering the effect which the variation of contact pressure due to the radial directional assembling tolerance between the bearing and the housing influences on the axial and radial directional displacement characteristics of the bearing. Furthermore, for several assembling systems of bearings and housings having all different assembling tolerances, we proposed a method to predict exactly the variation of the bearing preload which is sensitive to the thermal deformation by showing the propriety with experimental results.

• 한국항공운항학회지
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• 제18권4호
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• pp.44-50
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• 2010

Structural vibration is a significant problem in many multi-part or multi-component assemblies. In aircraft industry, structures are composed of various fasteners, such as bolts, snap, hinge, weld or other fastener or connector (collectively "fasteners"). Due to these, prediction and design involving dynamic characteristics is quite complicated. However, the current state of the art does not provide an analytical tool to effectively predict structure's dynamic characteristics, because consideration of structural uncertainties (i.e. material properties, geometric tolerance, dimensional tolerance, environment and so on) is difficult and very small fasteners in the structure cause a huge amount of analysis time to predict dynamic characteristics using the FEM (finite element method). In this study, to resolve the current state of the art, a new approach is proposed using the FEM and probabilistic analysis. Firstly, equivalent elements are developed using simple element (e.g. bar, beam, mass) to replace fasteners' finite element model. Developed equivalent elements enable to explain static behavior and dynamic behavior of the structure. Secondly, probabilistic analysis is applied to evaluate the PDF (probability density function) of dynamic characteristics due to tolerance, material properties and so on. MCS (Monte-Carlo simulation) is employed for this. Proposed methodology offers efficiency of dynamic analysis and reality of the field as well. Simple plates joined by fasteners are taken as an example to illustrate the proposed method.

• 한국방사선학회논문지
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• 제3권4호
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• pp.23-28
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• 2009

단색 엑스선은 적은 방사선 피폭으로 대조도가 높은 의료영상을 만들 수 있다. 엑스선 튜브와 다층박막 거울을 결합하면 높은 플루언스의 단색 엑스선을 얻을 수 있다. 몰리브덴(Mo) 타깃을 갖는 엑스선 튜브에서 Mo 특성방사선(17.5keV)을 높은 반사율로 획득하기 위한 W/C 다층박막 거울의 최적화를 수행하였다. 반사율이 최대가 되는 조건에서 두께주기와 두께비를 결정하였다. 최적 설계된 다층박막 거울에 대한 두께주기와 브래그 정렬에 대한 공차를 구하였다. 증착(deposition) 공차 0.2nm와 회전정렬 공차 ${\pm}0.01^{\circ}$에서 이론 반사율의 85% 이상에 해당하는 반사율이 얻어질 수 있다. 다층박막 거울을 이용하면 높은 플루언스의 특성방사선을 얻어 낼 수 있기 때문에 의료영상 획득 장치에 많이 사용될 것이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.901-905
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• 1992

The manual procedure of drafting engineering design is fast becoming obsolete. One of the important areas in CAPP is to automate tolerance assignment which is encountered in mechanical part design. This paper presents an approach for automating tolerance assignment using CAD database and tolerancing database in CAD drawing. The system is consisted of four major functions feasture extraction, feaure inferencing, rule-based tolerance allocation, and automatic upating. Auto CAD R.II is employed as CAD system and a computer progran is developed by using Auto LISP on PC-386.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.461-462
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• 2013