• 품질경영학회지
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• 제28권2호
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• pp.103-122
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• 2000

Process capability indices (PCI) $C_p\;C_{pk},\;C_m,\;and\;C_{pmk}$ are widely used to evaluate the process performance. The PCI's have been evolved to consider the 'off targetness' more adequately. However, all of these indices are found to be inconsistent with the proportion of nonconforming items, in some cases. That is, the PCI for a process may result in higher value even when the proportion of defectives increases. For these reasons, we propose a new capability index, $c_{pd}$, which is consistent with the defect rate. The characteristics of the new PCI, $c_{pd}$ are investigated with respect to the existing PCI's. Some statistical properties of an estimator for $c_{pd}$ are also investigated by a Monte Carlo simulation. Sensitivity study under minor deviation from normality is also performed to show the robustness of $c_{pd}$. A good estimator for $c_{pd}$ is under study.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2011년도 추계학술대회
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• pp.213-217
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• 2011

The research shows misuse cases of quantitative regression analysis used in QC circle activity and six sigma movement which presents guidelines of correct use for quality practitioners. Additionally, the qualitative regression analysis that responses nonconforming ratio of variable y, is reviewed based on misuse cases for proper use by practitioners in the field. In most cases, there are frequent errors that involve the correlation analysis or ANOVA, regardless of using quantitative regression analysis. In addition, qualitative regression analysis for the nonconforming ratio that has dependent variable of discrete and categorical data, is often applied with quantitative regression and result in ineffective quality improvement.

• 대한안전경영과학회지
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• 제11권1호
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• pp.131-136
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• 2009

The research develops the calculation steps of Z sigma level, process capability index(PCI) and process performance index(PPI) applicable to the discrete process in the service industry. The paper presents three following topics used related process indexes according to the precision and accuray in the continuous process. The contents include diverse process indexs for nonconformities by SPC attribute control charts and bias coefficient. The same technique of the nonconformites is also used in the nonconforming units. The practical examples are provided to help easier understanding for users.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 1999년도 추계학술대회
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• pp.247-257
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• 1999

There are several models for process quality assurance by quality system(ISO 9000), process capability analysis, acceptance control chart and so on. When a high level process capability has been achieved, it takes a long time to monitor the process shift, so it is sometimes necessary to develop a quicker monitoring system. To achieve a quicker quality assurance model for high-reliability process, this paper presents a model for process quality assurance when the fraction nonconforming is very small. We design an acceptance control chart based on variable quality characteristic and time-censored accelerated testing. The distribution of the characteristics is assumed to be normal of lognormal with a location parameter of the distribution that is a linear function of a stress. The design parameters are sample size, control limits and sample proportions allocated to low stress. These parameters are obtained under minimization of the relative variance of the MLE of location parameter subject to APL and RPL constraints.

• 대한산업공학회지
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• 제29권3호
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• pp.239-246
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• 2003

Individual items are produced continuously from an industrial process. Each item is checked to determine whether it satisfies a lower screening limit for the quality characteristic which is the weight of an expensive ingredient. If it does, it is sold at a regular price; if it does not, it is reprocessed or sold at a reduced price. The process mean may be adjusted to a higher value in order to reduce the proportion of the nonconforming items. Using a higher process mean, however, may result in a higher production cost. In this paper, the optimal process mean and lower screening limit are determined in situations where the probability that an item functions well is given by a logistic function of the quality characteristic. Profit models are constructed which involve four price/cost components; selling prices, cost from an accepted nonconforming item, and reprocessing and inspection costs. Methods of finding the optimal process mean and lower screening limit are presented and numerical examples are given.

• Human Ecology Research
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• 제53권3호
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• pp.253-263
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• 2015

This study investigates the effect of consumer culture and awareness of wedding ceremonies between parents and children as well as preference for a simple wedding in order to develop a simple wedding concept. The data for statistical analysis came from 375 of children 216 and parents 159. Data was analyzed with t -test, analysis of variance, exploratory factor analysis, Cronbach's $\alpha$ and regression analysis by SPSS ver. 18.0. The results were summarized as follows. First, children had a higher symbolic consumption than parents and parents had a higher functional consumption than children. Second, children prefer a discriminate and characteristic small wedding, while parents prefer an economical, meaningful and nonconforming simple wedding. The variables that effect parents simple wedding preferences were consumer culture, awareness of wedding ceremony, gender, and education; those of children were, consumer culture, awareness on wedding ceremony, gender, and age. Children had a functional and economical consumption focused on meaningfulness and rationale of the wedding, they prefer an economical meaningful small wedding. Children had functional consumption that prefers a discriminate characteristic small wedding and a nonconforming small wedding compared to men. Parents did not have symbolic consumption and focused on the meaningfulness and rationale of the wedding, they prefer an economical meaningful small wedding. Parents focused on the meaningfulness and rationale of the wedding; in addition women prefer a discriminate characteristic small wedding compared to men. Parents had functional consumption and focused on the meaningfulness and rationale of the wedding with a preference for a nonconforming small wedding.

• 품질경영학회지
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• 제35권4호
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• pp.147-158
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• 2007

Owing to the rapid growth in automated manufacturing systems, screening inspection becomes an attractive practice for removing nonconforming items, and it has been suggested that inspection will essentially become an inherent part of modem manufacturing processes. In this paper, we propose rectifying screening inspections which allow quality practitioners to use performance and surrogate variables interchangeably in real-time applications. Two screening inspections are considered; a statistically-based screening inspection to reduce the current proportion of nonconforming items to a specified AOQ(average outgoing quality) after screening, and an economically-based screening inspection where the tolerance limit is determined so that the expected total cost is minimized. It is assumed that the performance variable and the surrogate variable are jointly normally distributed. For two screening inspections, methods of finding the optimal solutions are presented and numerical examples are also given.

• 품질경영학회지
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• 제45권4호
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• pp.829-846
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• 2017

Purpose: This paper compares the effectiveness of typical selective assembly criteria and suggests the most promising one. Based on the result of a computer simulation, the key issues of selective assembly are examined and the best criterion is recommended from the effectiveness perspective. Methods: Using JAVA program, production of ten thousand units for each pair of components are simulated for selective assembly of the two types. And the number of mismatching and the fraction nonconforming for each criterion are determined. Results: The best match criterion appeared to be most promising from the perspectives of both mismatching and nonconforming problems. Its effectiveness appears to be also good even when the precision of one component is different from that of the other. Conclusion: For designing an optimal method for selective assembly, the best match criterion is recommendable as the base criterion.

• 산업경영시스템학회지
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• 제22권52호
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• pp.69-79
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• 1999

The main objective of this study are to propose two methods that would be a comprehensive measure of evaluation for non-normal process capability with Beta distributions. First method is introduced using process capability index $C_{psk}$ by the Pearson system and Johnson system. The Pearson system and the Johnson System selected for process capability index calculation have a equivalent result of this study that the ranking of the seven indices in terms of sensitivity to departure of the process median from the target value from the most sensitive one up to the least sensitive are $C^{*}_{pm}$ , $C_{psk}$ , $C_{s}$ , $C_{pmk}$ , $C_{pm}$ , $C_{pk}$ , $C_{p}$ . Second method show using the percentage nonconforming by the Pearson, Johnson and Burr functions. In thus study, we find that the Pearson system and the Burr system are a reasonable method to estimate percentage nonconforming. But, the exact procedure for deriving this estimate will be based on Beta distribution. Accordingly, if a process is not normally distributed , but normal-based techniques are used serious errors can result.

• 산경연구논집
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• 제15권2호
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• pp.11-18
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• 2024

Purpose: This research examines how people react to nonconforming behavior such as entering a luxury boutique wearing gym clothes rather than an elegant outfit or wearing red sneakers in a professional setting. Nonconforming behaviors, as costly and visible signals, can act as a particular form of conspicuous consumption and lead to a positive inference of status and competence in the eyes of others. Research design, data, and methodology: A series of studies demonstrate that people confer higher status and competence rather than conforming individuals using 2-way ANOVA through employees in luxury stores and students at university. Results: According to the empirical studies, observers who witness the nonconformity behavior have positive inferences of status and competence rather than conformity behavior. These positive inferences derived from signals of nonconformity are moderated by individual differences in prior knowledge and regulatory focus. Conclusions: Through three empirical studies, observers who witnessed role-breaking in prestigious and professional situations found that the individuals who performed the nonconformity behavior had higher status and competence rather than conformity behavior. Even in Korea, a collectivist culture, observers who witnessed nonconformity behavior showed that they gave higher evaluations to the people who behaved informally.