• 한국품질경영학회:학술대회논문집
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• 한국품질경영학회 2010년도 춘계학술대회
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• pp.123-128
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• 2010

This article investigates economic-statistical design of VSI(variable samling interval) charts considering Various Runs Rules. Most recent adaptive control charts are conplex designs. Actually It's not easy to operating control quality process. We propose a procedure for designing VSI Runs charts, based on Lorenzen and Vence's model. The optimal design parameters of the charts can be determined by minimizing the cost model. And computational experiments show that the VSI Runs Rules charts is superior to the FSSI Runs Rules charts in the economic-statistical characterisitics.

• 대한산업공학회지
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• 제41권6호
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• pp.521-529
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• 2015

Statistical process control techniques have been greatly implemented in industries for improving product quality and saving production costs. As a primary tool among these techniques, control charts are widely used to detect the occurrence of assignable causes. In most works on the control charts it considered the problem of monitoring the mean and variance, and the quality characteristic of interest is normally distributed. In some situations monitoring of the minimum and maximum values is more important and the quality characteristic of interest is the Weibull distribution rather than a normal distribution. In this paper, we consider the statistical design of minimum and maximum control charts when the distribution of the quality characteristic of interest is Weibull. The proposed minimum and maximum control charts are applied to the wind data. The results of the application show that the proposed method is more effective than traditional methods.

• 품질경영학회지
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• 제32권1호
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• pp.92-101
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• 2004

Tris paper present an economic statistical design which have statistically constraints for the optimal design of an EWMA control charts with variable sampling interval. Cost function use that proposed by Lorenzen and Vance, and the optimal design parameters include the sample size, control limit width, sampling interval, EWMA weight value. Comparisons between VSI EWMA control charts optimal economic design and optimal economic statistical designs show the following fact. Although have demerits which are more costly than economic design, have merits which to detect shifts more efficiently and to improve statistical performance.

• Communications for Statistical Applications and Methods
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• 제27권1호
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• pp.65-77
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• 2020

Geometric charts are effective in monitoring the fraction nonconforming in high-quality processes. The in-control fraction nonconforming is unknown in most actual processes; therefore, it should be estimated using the Phase I sample. However, if the Phase I sample size is small the practitioner may not achieve the desired in-control performance because estimation errors can occur when the parameters are estimated. Therefore, in this paper, we adjust the control limits of geometric charts with the bootstrap algorithm to improve the in-control performance of charts with smaller sample sizes. The simulation results show that the adjustment with the bootstrap algorithm improves the in-control performance of geometric charts by controlling the probability that the in-control average run length has a value greater than the desired one. The out-of-control performance of geometric charts with adjusted limits is also discussed.

• 산업경영시스템학회지
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• 제37권4호
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• pp.134-144
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• 2014

With the advent of lean-six sigma era, an extensive use of analytic tools such as control charts is required in the field of manufacturing. In relation to statistical quality control (SQC) or process control (SPC), the Korean standards have undergone a meaningful change. In this study, the theoretic backgrounds for evaluating the control limits in connection with the variable control charts are examined in view of better understanding the related constants and coefficients. This paper is intended to help the quality control practitioners understand the mathematical backgrounds by comparing related quality control constants and also to encourage them to make use of and to take the advantage of the variable control charts which are very useful for implementing the concept of lean-six sigma in many industrial sites.

• 품질경영학회지
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• 제44권1호
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• pp.1-16
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• 2016

Purpose: This paper reviews the papers on statistical quality control issues which are published in Journal of the Korean Society for Quality Management (KSQM) since 1965. The literature review is purposed to survey a variety of statistical quality control issues. Methods: By grouping all of statistical quality control issues into 3 categories:; quality inspections, control charts, and process capability analysis. Results: Grouping all of papers on statistical quality control published in journal of the KSQM for 50 years into 3 categories, we provide a chronological roadmap for individual categories, and summarize the contents and contributions of surveyed papers. Conclusion: The review paper is expected to provide future direction to improve statistical quality control theories and applications in manufacturing and service industries.

• 품질경영학회지
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• 제31권3호
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• pp.126-135
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• 2003

A basic assumption in standard applications of control charts is that the observations are statistically independent. However, this assumption is often violated from processes in many industries. The presence of autocorrelation has a serious impact on the performance of control charts, causing a dramatic increase in the frequency of false alarms. This paper considers a process in which the observations can be modeled as a first order autoregressive(AR(1)) process, and develops (equation omitted) charts with the variable sample size(VSS) scheme for monitoring the mean of this process.

• Communications for Statistical Applications and Methods
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• 제12권2호
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• pp.265-273
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• 2005

In this paper, we proposed multivariate EWMA control charts for both combine-accumulate and accumulate-combine approaches to monitor dispersion matrix of multiple quality variables. Numerical performance of the proposed charts are evaluated in terms of average run length(ARL). The performances show that small smoothing constants with accumulate-combine approach is preferred for detecting small shifts of the production process.

• 품질경영학회지
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• 제22권2호
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• pp.20-32
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• 1994

This paper is concerned with the design of four control charts for real-time monitoring of the continuous flow processes. Control charts for both uncorrelated data and correlated data are designed using the Kalman filtering techinque. The relative performance between the designed control charts and traditional control charts is evaluated in terms of the Average Run Length(ARL). Results show that the Adaptive EWMA control charts designed for uncorrelated data has better performance when process mean is shifted, while the residual control charts for correlated data has better performance when process is in control.

• 한국콘텐츠학회논문지
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• 제16권6호
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• pp.529-536
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• 2016

본 연구의 목적은 차별적 경찰대응전략의 품질을 평가하는 것이다. 새로운 경찰대응시스템이 도입된 지 약 3년이 지났지만, 이를 실증적으로 평가한 연구는 미비한 실정이다. 2가지 종류의 통계적 품질관리 기법을 활용하여, 2012년 한해동안 익산경찰서에 신고된 약 3,000건의 경찰데이터를 분석하였다. "Xbar-R 관리도"의 분석결과, 경찰은 긴급출동신고전화 (Code 1)에 지속적으로 신속히(3분 이내) 대응하지 못하는 것으로 나타났다. 더불어 "P 관리도"의 분석결과, 경찰은 비긴급출동신고전화 (Code 2)에 5분이내로 대응하지 못한 출동건수의 월별 상이성이 큰 것으로 나타났다. 본 연구에서 알 수 있듯이 경찰이 추구하는 "신속한" 수준의 대응전략에 있어 코드별 목표대응시간에 대하여 재검토 할 필요성이 제기된다.