• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.903-912
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• 2009

This study is focused on simulation-based dimensional tolerance optimization process (DTOP) to minimize vehicle pulls by reduction of dimensional variation in front suspension system. In previous studies, the effect of tires and wheel alignment sensitivity have mainly been investigated to eliminate vehicle pulls in nominal design condition without allocating optimal tolerance level for selected components, among various factors regarding vehicle pulls such as vehicle design parameters, vehicle weight balance, tires, and environmental factors. Unfortunately, there are wide variations in the real vehicle, and these have impacted actual vehicle pulls, especially wheel alignment effects from suspension geometry variation has not been considered in the previous studies. In the tolerance design of suspension, tolerance variables with the uncertainty such as parts dimensional variation, assembly process, datum position and direction, and assembly tool tolerance has a great influence on the variation of the suspension dimensional performances. This study introduces total vehicle pull prediction model in considering major key factors for vehicle pull sensitivity. The Monte Carlo-based tolerance analysis model using Taguchi robust method is developed to optimize dimensional tolerance parameters, satisfying on the target variation level.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.829-832
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• 2002

With the increase of storage density, high rotational speed and high access technologies in optical disk drive, mechanical issues, mainly noise and vibration, become critical. Up to now the researches of rubber mount for anti-vibration focused on how to calculate the static and the dynamic stiffness of rubber mount and leaved out of consideration of the dimensional tolerance of rubber mount for anti-vibration. This paper presents the effects of dimensional tolerance of rubber mount for anti-vibration on the dynamic characteristics of optical disk drive by finite element analysis and dynamic test. The relation between dimensional tolerance and dynamic characteristics of optical disk drive is observed and discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.9
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• pp.661-667
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• 2002

With the increase of storage density, high rotational speed and high access technologies in optical disk drive, mechanical issues, mainly noise and vibration, become critical. Up to now the researches of rubber mount for anti-vibration focused on how to calculate the static and the dynamic stiffness of rubber mount and loaned out consideration of the dimensional tolerance of rubber mount for anti-vibration. This paper presents the effects of dimensional tolerance of rubber mount for anti-nitration on the dynamic characteristics of optical disk drive by finite element analysis and dynamic test. The relation between dimensional tolerance and dynamic characteristics of optical disk drive is observed and discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.86-89
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• 2000

In cold forging by multi stage former, crowing process is important process for the high production rate and automation of forging process. But various cropping defects occur in cropping process such as orthogonality, ovality and unevenness, etc. These defects have harmful effects on the dimensional tolerance of products and tool life. So in this study, the cropping experiment is performed to examine influence of cropping process variables(clearance, cutting velocity, H/D) on occurrence of crowing defects and optimum process variables are selected, and then FE analysis is performed to verify influence of these defects on dimensional tolerance and tool life.

• Journal of the Semiconductor & Display Technology
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• v.16 no.4
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• pp.52-58
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• 2017

In this study, we tried to analyze and measure the correlation between the part dimensional tolerance empirically applied by the designer and the final performance of the equipment, which is expressed as the pressing pressure uniformity. For this purpose, the dimensional tolerances and pressing pressure uniformity of eight laminator equipments were measured actually. As a result of the correlation analysis, it was confirmed that the tolerance grade for each dimension determined by the designer was valid. In the case of laminator equipment, the driving parts and the flatness have the largest influence on the uniformity of the pressing pressure.

• 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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.10 s.241
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• pp.1377-1383
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• 2005

A general and efficient methodology has been developed to analyze dimensional variations of an assembly, taking into account of weld distortion. Weld distortion is generally probabilistic because of the random nature of welding parameters such as the welding speed, maximum welding temperature, ambient temperature, etc. The methodology is illustrated through a very simple example of two perpendicular plates fillet-welded to each other. Two steps comprise the methodology: establishment of a weld-distortion database, and tolerance analysis using the database. To establish the database, thermo-elasto-plastic finite element analyses are conducted to compute the weld distortion for all combinations of discrete values of major welding parameters. In the second step of tolerance analysis, the weld distortion retrieved from the database is used in addition to the dimensional tolerances of the parts. As a result of such an analysis, sensitivities of the assembly's dimensional variations to the part tolerances and weld distortion are obtained, which can be help improve the dimensional quality of the assembly.

• Journal of Korean Institute of Industrial Engineers
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• v.31 no.1
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• pp.36-43
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• 2005

It is the basic requirement of design process of parts assembly to specify geometric dimensions and tolerances of product characteristics. Among them, tolerance stack analysis is one of the important methods to specify tolerance zone. Tolerance stack analysis is to calculate gap using tolerances which includes geometric and coordinate dimensions. In this study, we suggested more general method called the virtual method to analyze tolerance stack. In virtual method, tolerance zone is formed by combination of dimensional tolerance, geometric tolerance and bonus tolerance. Also tolerance zone is classified by virtual boundary condition and resultant boundary condition. So gap can be defined by combination of virtual boundary and/or resultant boundary. Several examples are used to show the effectiveness of new method comparing to other methods.

• Korean Journal of Computational Design and Engineering
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• v.17 no.6
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• pp.398-408
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• 2012

This paper investigates the tolerance stack-up in a commercial sliding-type mobile phone model developed by a Korean electronics company, with focus on the dimensional quality of the gap between the sliding top and the main body. The tolerance analysis in this study is done using a commercial software package, which runs Monte Carlo simulations to produce the statistical distributions of the gap size at desired locations. Such an analysis revealed that the original design did not yield the desired dimensional quality of the gap. Through a series of systematic analyses and syntheses, an improved design is proposed for the nominal dimensions and tolerances of selected features of the parts. The proposed design was validated, through tolerance analysis simulation, to meet the desired requirement of the gap quality.

• Journal of Welding and Joining
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• v.18 no.3
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• pp.122-130
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• 2000

Due to the inherent dimensional uncertainty, the tolerances accumulate in the assembly of plasma cutting torch. Tolerance accumulation has serious effect on the performance of the plasma torch. This study proposes a statistical tolerance propagation model, which is based on matrix transform. This model can predict the final tolerance distributions of the completed plasma torch assembly with the prescribed statistical tolerance distribution of each part to be assembled. Verification of the proposed model was performed by making use of Monte Carlo simulation. Monte Carlo simulation generates a large number of discrete plasma torch assembly instances and randomly selects a point within the tolerance region with the prescribed statistical distribution. Monte Carlo simulation results show good agreement with that of the proposed model. This results are promising in that we can predict the final tolerance distributions in advance before assembly process of plasma torch thus provide great benefit at the assembly design stage of plasma torch.