• 대한산업공학회지
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• 제11권2호
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• pp.189-194
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• 1985

Process Capability Index is defined as a ratio between predetermined tolerance and natural tolerance of existent process ($6{\sigma}$). And it is widely used as a performance measure for quality control activities, and a criterion for process classification. This paper developed a unity-fixed process capability table for convenience to calculate process capability and showed how to use it.

• 품질경영학회지
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• 제42권2호
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• pp.209-219
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• 2014

Purpose: The purpose of this study is to develop the statistical test for process capability index $C_p$ based on mixture normal process. Methods: This study uses Bootstrap method to calculate the approximate P-value for various simulation conditions under mixture normal process. Results: This study indicates that our proposed method is effective way to test for process capability index $C_p$ based on mixture normal process. Conclusion: This study finds out that statistical test for process capability index $C_p$ based on mixture normal process is useful for real application.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2008년도 춘계학술대회
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• pp.417-428
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• 2008

Designers have to consider voice of customer, process capability, manufacturing standards & condition, manufacturing method, characteristics of products to decide tolerances. Especially, in case of position of hole and pin, designers have to consider process capability to decide tolerances. The traditional position tolerances used in a drawing are theoretical values which are allocated to position under the worst case assembling condition that both hole and pin are the maximum material condition(MMC). However, When the process capability is high, more exact product size can be produced under stable manufacturing condition. larger clearance of hole and pin can be allocated. In this point of view, manufacturer could increase the yield by allocating larger position tolerance than theoretical position tolerance of hole and pin considering process capability.

• 대한안전경영과학회지
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• 제11권1호
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• pp.75-85
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• 2009

Designers have to consider voice of customer, process capability, manufacturing standards & condition, manufacturing method and characteristics of products to decide tolerances. Especially, in case of position of hole and pin, designers have to consider process capability to decide tolerances. The traditional position tolerances used in a drawing are theoretical values which are allocated to position under the worst case assembling condition that both hole and pin are the maximum material condition(MMC). However, when the process capability is high, more exact product size can be produced under stable manufacturing condition. Larger clearance of hole and pin can be allocated. In this point of view, manufacturer could increase the yield by allocating larger position tolerance than theoretical position tolerance of hole and pin considering process capability.

• 품질경영학회지
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• 제34권3호
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• pp.66-72
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• 2006

The process capability indices are widely used to measure the capability of the process to manufacture items within the specified tolerance. Most evaluations on process capability indices focus on point estimates, which may result in unreliable assessments of process performance. The index $C_p$ has been widely used in various industries to assess process performance. In this paper, we propose new testing procedure on assessing $C_p$ index for practitioners to use in determining whether a given process is capable. The provided approach is easy to use and the decision making is more reliable. Whether a process is clearly normal or nonnormal, our bootstrap testing procedure could be applied effectively without the complexity of calculation. A numerical result based on the proposed approach is illustrated.

• 품질경영학회지
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• 제15권1호
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• pp.47-54
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• 1987

It is common that the process capability fluctuates as time passes, but concentrates to the mean value. To keep up process capability with given limits is vital to stability of process. Various control charts, especially ${\sigma}-chart$, have been used for analyzing process capability, but It sometimes can not give distinct answer. So this paper introduces another analyzing method by ARMA (autoregressive moving average) which is originally developed for forecasting, and demonstrates the analyzing methodology through a case study.

• 품질경영학회지
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• 제26권1호
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• pp.88-98
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• 1998

Process capability indices are used to determine whether a production process is capable of producing items within a specified tolerance. Using conditional distribution, we study some process capability indices ${\hat{C}}_{Gp}$, ${\hat{C}}_{Gpk}$, ${\hat{C}}_{Gpm}$ under conjugate prior distribution. We consider some process capability indices with Gibbs sampling method. Also, we examine some small sample properties related to these estimaters by some simulations.

• Journal of the Korean Data and Information Science Society
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• 제24권3호
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• pp.465-475
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• 2013

공정능력을 측정하고 분석하기 위하여 공정능력지수가 매우 중요한 역할을 한다. 흔히 품질수준은 공정능력지수들에 의해 측정된다. 세 가지 공정능력지수 $C_p$, $C_{pk}$, $C_{pm}$들은 품질 현장에서 프로세스 성과를 평가하는 데 널리 유용하게 사용되는 바, 이들 추정량들의 상관관계를 보다 명확하게 규명, 연구하여 적절히 활용할 필요가 있다. 본 논문에서는 공정표본이 정규분포에 따를 때 이러한 지수들의 추정량들에 대한 점근적 상관성을 연구하였다. 제2절에서는 공정능력지수 $C_p$, $C_{pk}$, $C_{pm}$들을 정의하여 기본적인 관계를 설명하였고, 제3절에서는 단일변량 정규공정하에서의 점근적인 상관계수를 구체적으로 계산, 규명하였다. 이러한 연구결과를 이용하여 보다 정확한 공정능력지수들의 상관관계를 통해 필요한 분석을 수행하는 것이 바람직할 것이다.

• 산업경영시스템학회지
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• 제41권2호
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• pp.174-183
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• 2018

In the industrial fields, the process capability index has been using to evaluate the variation of quality in the process. The traditional process capability indices such as $C_p$, $C_{pk}$, $C_{pm}$ and $C^+_{pm}$ have been applied in the industrial fields. These traditional process capability indices are mainly applied in the univariate analysis. However, the main streams in the recent industry are the multivariate manufacturing process and the multiple quality characteristics are corrected each other. Therefore, the multivariate statistical method should be used in the process capability analysis. The multivariate process indices need to be enhanced with more useful information and extensive application in the recent industrial fields. Hence, the purpose of the study is to develop a more effective multivariate process index ($MC_{pI}$) using the multivariate inverted normal loss function. The multivariate inverted normal loss function has the flexibility for the any type of the symmetrical and asymmetrical loss functions as well as the economic information. Especially, the proposed modeling method for the multivariate inverted normal loss function (MINLF) and the expected loss from MINLF in this paper can be applied to the any type of the symmetrical and asymmetrical loss functions. And this modeling method can be easily expanded from a bivariate case to a multivariate case.

• 품질경영학회지
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• 제30권3호
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• pp.66-78
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• 2002

Process capability indices are being used as indicators for measurements of process capability for SPC of quality assurance system in industries. In view of the enhancement of customer satisfaction, process capability indices in which loss functions are used to deal with the economic loss In the processes deviated from the target, are in an adequate representation of the customer's perception of quality In this connection, the loss function has become increasingly important in quality assurance. Taguchi uses a modified form of the quadratic loss function to demonstrate the need to consider the proximity to the target while assessing its quality. But this traditional quadratic loss function is inadequate to assessing the quality and quality improvement since different processes have different sets of economic consequences on the manufacturing, Thereby, a flexible approach to the development of the loss function needs to be desired. In this paper, we introduce an easily understood loss function, based on reflection of probability density function of the normal distribution. That is, the Reflected Normal Loss function can be adapted to an asymmetric loss as well as to a symmetric loss around the target. We propose that, instead of the process variation, a new capability index, CpI using the Reflected Normal Loss Function that can accurately reflect the losses associated with the process and a new capability index CpI Is compared with the classical indices as $C_{p}$ , $C_{pk}$, $C_{pm}$ and $C_{pm}$ $^{+}$.>.+/./.