• Journal of the korean Society of Automotive Engineers
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• v.4 no.1
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• pp.1-4
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• 1982

우리가 흔히 쓰는 관리도에도 X over bar-R관리도, P(또는 Pn)관리도, C(또는 U)관리도가관리 도의 대종을 이루고 있다. 그러나 기계공업 특히 자동차공업분야에서는 기계가공 부품을 일일이 재기가 어렵거나 시간이 걸리므로 고-노고우 게이지(go-no go gauge)를 써서 선별하는 경우가 많다. 또 금형베품의 조립시에는 측정개소가 많기 때문에 어느 한 부분만을 제어서 관리할 수 없으므로 여러곳을 제어서 관리해야 하는데 이때 금형전체를 어떻게 맞출것인가, 혹은 제품의 공차관리를 어떻게 해나갈 것인가 하는 문제가 생긴다. 다음에 이러한 경우에 유용하게 쓰일 수 있는 관리도의 예를 소개하고자 한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.127-129
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• 2003

Recently. the efforts for the development of DVD concentrate on the high storage and multi-media. DVD has been manufactured by assembling many parts and it causes the vibration and noise. In this paper, one body rotor is proposed, which can make the nose and vibration be decreased. The injection mould for DVD rotor is designed by finite element analysis and the rotor is manufactured in the mould. The magnetic flux density is measured on the surface and it is compared with the design criteria.

• Journal of Welding and Joining
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• v.30 no.1
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• pp.78-84
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• 2012

Due to the inherent dimensional uncertainty, tolerances accumulate in the final assembly. Tolerance accumulation has serious effect on the performance of ECV assembly. This paper proposes a method of tolerance accumulation analysis using Monte Carlo simulation, which includes welding process in assemble process. This method can predict the final tolerance distributions of the completed assembly with the prescribed statistical tolerance distribution of each part to be assembled. With the inclusion of welding, another dimensional uncertainties due to partial melting is to be accounted as well. Partial melting of projection height was included in the tolerance propagation analysis. Verification of the proposed method was performed by making use of Monte Carlo simulation. Monte Carlo simulation results showed promising results in that we can predict the final tolerance distributions in advance before actual assembly process of precision machinery.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.137-141
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• 1995

회전기계에서 발생하는 진동 원인 중 약 60% 이상이 불평형(unbalance)에 의한 진동이다. 불평형은 기계의 과도한 진동을 유발시킬 뿐 아니라 베어링의 수명 단축 및 소음을 발생시킨다. 따라서, 기게의 수명을 연장시키고, 기계의 성능을 향상시키며 부드럽고 진동이 없는 운전을 위하여 평형잡이(balancing)는 절대적으로 중요하다. 불평형은 축 중심선에 대하여 회전체의 질량 분포가 비대칭이기 때문에 발생하는데 그 원인으로는 부품 자체가 비대칭에서 오는 설계 또는 제도 오차, 주물의 기포 및 용접의 불균일 등에 의한 재질상의 결함, 그리고 부품조립시 형상누적공차 등에 의한 가공.조립오차 등이 있다. ISO의 정의에 따르면 평형잡이는 회전체의 질량 분포를 조사하고 필요하다면 저널의 진동과 베어링의 작용력들이 운전속도에 대응하는 주파수에서 특정한 한계내에 있도록 보증하게 하기 위한 조정을 하는 과정이다. 불평형 상태에 대한 조사도 평형잡이로 표현된다. 그러나 수정이 필요하다고 간주된다면 수행된다. 모든 회전체는 초기 불평형(initial unbalance)이라 불리는 임의의 불평형을 가지고 출발한다. 완벽하게 평형이 잡힌 회전체를 달성하는 것이 평형잡이 작업의 목적은 아니다. 임의의 잔류 불평형(residual unbalance)은 항상 허용된다. 경제적인 이유에서 회전체는 일반적으로 요구되는 적절한 허용치보다 더 이상 평형잡이를 하지 않는다. 현장에서 현장 평형잡이를 수행하게 될 경우, 가끔 계산된 수정질량이 매우 클 경우가 있다. 이때 기게의 조건상 큰 수정질량을 부착하기가 곤란한 경우가 자주 발생한다. 작은 수정질량으로 평형잡이를 할 수 있다면 기계의 안정성 면에서 매우 유리하다. 따라서 본 연구에서는 영향계수법(Influence Coefficient Method : ICM)의 기본 개념과 유전 알고리즘(Genetic Algorithm : GA)을 이용하여 회전기계의 안정성을 보장할 수 있는 허용진동 내에서의 최적 수정질량 계산법을 제시한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.468-476
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• 2019

This paper presents the means of improving the strength of LTV's FRP structure for resolve and prevent quality problems. LTV secures enough kerb weight by applying FRP materials at hood and rear van assembly. However, because of FRP's inherent limitations, many initial quality problems such as crack at connections have occurred. Moreover, hood assy' is concerned about fall of endurance, because hood assy' have operated in abnormal condition. Therefore, this study executes lamination structure optimizations of FRP structure for improving bending strength. As a results, hood and rear van's bending strength at connections is improved 8.1 times and 1.5 times, respectively. Also hood assy's plate secures endurance life and improve 1.7 times of critical load about abnormal operating conditions through 1.4 times improvement of bending strength.

• Korean Journal of Computational Design and Engineering
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• v.1 no.3
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• pp.215-223
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• 1996

Every mechanical part 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 while considering their order of precedence. It would be desirable if the assemblability of parts could be verified in the computer when the tolerances on the parts are store together with the geometric model of the parts of an assembly and their assembled state. Therefore, a new method is proposed to represent geometric tolerances and to determine the assemblability. This method determines the assemblability by subdividing the ranges of relative motion between parts until there exists the subdivided regions that do not cause the interference.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.258-259
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• 2003

보호층 0.1mm두께의 20GB이상의 광디스크를 기록·재생하는 High Density Optical System에서는 Blue-violet laser와 NA(Numerical Aperture)0.85의 High NA의 대물렌즈를 사용한 Optical Pick Up이 필요로 된다. 종래의 대물렌즈는 glass 또는 plastic제의 2매 조합 대물렌즈가 많이 사용되어지고 있는데, 이는 두 렌즈간의 거리를 일정하게 유지시키기 위한 홀더 조립시의 공차가 엄격히 요구되며, 2매 조합 대물렌즈를 구동시키기 위한 actuator의 부피와 무게를 증가시킴으로서 구동감도를 감소시키는 단점이 있다. (중략)

• Korean Journal of Computational Design and Engineering
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• v.12 no.4
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• pp.263-273
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• 2007

All manufactured parts and tooling have unavoidable variations from their nominal shapes. During assembly, compliant parts are further deformed by relatively rigid assembly tooling. Lack of Knowledge regarding variations and deformations often results in expensive problems. Most current computer-aided design systems are based on ideally sized, ideally located and rigid geometry. This paper proposes a model for the assembly of compliant, non-ideal part. We start by defining tolerance analysis as the process of simulation the variation of a product or a subassembly when given the tolerance of required parts. Analysis is then done by finite element analysis and using the material properties of the actual parts to be assembled. Using the result, estimate the weld process.

• IE interfaces
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• v.16 no.spc
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• pp.39-44
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• 2003

As one of many design variables, the role of dimension tolerances is to restrict the amount of size variation in a manufactured feature while ensuring functionality. In this study, a nonlinear integer model has been modeled to allocate the optimal tolerance to each individual feature at a minimum manufacturing cost. While a normal distribution determines statistically worst tolerances with its symmetrical property in many previous tolerance allocation studies, a asymmetrical distribution is more realistic because its mean is not always coincident with a process center. A nonlinear integer model is modeled to allocate the optimal tolerance to a feature based on a beta distribution at a minimum total cost. The total cost as a function of tolerances is defined by machining cost and quality loss. After the convexity of manufacturing cost is checked by the Hessian matrix, the model is solved by the Complex Method. Finally, a numerical example is presented demonstrating successful model implementation for a nonlinear design case.

• Journal of Aerospace System Engineering
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• v.12 no.4
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• pp.75-80
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• 2018

The working principle of a satellite camera involves a focusing mechanism for controlling the focus of the optical system, which is essential for proper functioning. However, research on focusing mechanisms of satellite optical systems in Korea is in the beginning stage and developed technology is limited to a thermal control type. Therefore, in this paper, we propose a motor-driven focusing mechanism applicable to small satellite optical systems. The proposed mechanism is designed to generate z-axis displacement in the secondary mirror by a motor. In addition, three flexure hinges have been installed on the supporter for application of preload on the mechanism resulting in minimization of the alignment error arising due to manufacturing tolerance and assembly tolerance within the mechanism. After fabrication of the mechanism, the alignment errors (de-space, de-center, and tilt) were measured with LVDT sensors and laser displacement meters. Conclusively, the proposed focusing mechanism could achieve proper alignment degree, which can be applicable to small satellite optical system.