• 제목/요약/키워드: Modified Control Chart

검색결과 26건 처리시간 0.021초

로버스트 추정에 근거한 수정된 ${\bar{x}}$-s 관리도의 설계 (Design of Modified ${\bar{x}}$-s Control Chart based on Robust Estimation)

  • 정영배;김연수
    • 산업경영시스템학회지
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    • 제38권1호
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    • pp.15-20
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    • 2015
  • Control charts are generally used for process control, but the role of traditional control charts have been limited in case of a non-contaminated process. Traditional ${\bar{x}}$-s control chart has not been activated well for such a problem because of trying to control processes as center line and control limits changed by the contaminated value. This paper suggests modified ${\bar{x}}$-s control chart based on robust estimation. In this paper, we consider the trimmed mean of the sample means and the trimmed mean of the sample standard deviations. By comparing with ARL value, the responding results are decided. The comparison resultant results of traditional control chart and modified control chart are contrasted.

현장에서 활용이 가능한 수정 관리도 제안 (PROPOSE MODIFIED CONTROL CHART FOR MANAGEMENT IN REAL FIELD)

  • 이상복;박노국
    • 벤처창업연구
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    • 제7권2호
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    • pp.151-156
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    • 2012
  • 본 논문에서 우리는 동시에 볼 수 있는 수정된 3개의 관리도를 제안하였다. 첫번째 곤리도는 샘플 데이터로만 그려진 관리도이다. 두번째 관리도는 처음 관리도에 상하한 규격을 포함한 관리도이다. 세번째 관리도는 목표값이 포함되고 오랜 기간 동안의 데이터로 계산된 알려진 평균과 표준편차로 계산된 상 하한 관리선이 포함된 관리도이다. 3개의 관리도를 동시에 보면 즉시 공정의 문제점을 알아낼 수 있는 정점이 있다. 이 논문에서 제안된 방법이 현장에서 활용되어 도움을 주길 희망한다.

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로버스트 추정에 근거한 수정된 다변량 $T^2$- 관리도 (Modified Multivariate $T^2$-Chart based on Robust Estimation)

  • 성웅현;박동련
    • 품질경영학회지
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    • 제29권1호
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    • pp.1-10
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    • 2001
  • We consider the problem of detecting special variations in multivariate $T^2$-control chart when two or more multivariate outliers are present. Since a multivariate outlier may reflect slippage in mean, variance, or correlation, it can distort the sample mean vector and sample covariance matrix. Damaged sample mean vector and sample covariance matrix have difficulty in examining special variations clearly, An alternative to detection outliers or special variations is to use robust estimators of mean vector and covariance matrix that are less sensitive to extreme observations than are the standard estimators $\bar{x}$ and $\textbf{S}$. We applied popular minimum volume ellipsoid(MVE) and minimum covariance determinant(MCD) method to estimate mean vector and covariance matrix and compared its results with standard $T^2$-control chart using simulated multivariate data with outliers. We found that the modified $T^2$-control chart based on the above robust methods were more effective in detecting special variations clearly than the standard $T^2$-control chart.

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비정규 공정하에 붓스트랩 EWMA관리도의 수행도 평가 (Evolution of Performance for Bootstrap EWMA Control Chart under Non-normal Process)

  • 이만웅;송서일
    • 산업경영시스템학회지
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    • 제25권2호
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    • pp.50-56
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    • 2002
  • In this study, we establish bootstrap control limits for EWMA chart by applying the bootstrap method, called resampling, which could not demand assumptions about pre-distribution when the process is skewed and/or the normality assumption is doubt. The results obtained in this study are summarized as follows : bootstrap EWMA control chart is developed for applying bootstrap method to EWMA chart, which is more sensitive to small shifts of process. With the purpose of eliminating a skewness of the resampling distribution, the bootstrap control limits are established by using a modified residual, and its performance is analyzed by ARL. It is shown that the bootstrap EWMA control chart developed in this study includes the properties of standard EWMA control chart that is sensitive to a small shift, and detects process in out of control more quickly than standard EWMA chart.

Multiparameter CUSUM charts with variable sampling intervals

  • Im, Chang-Do;Cho, Gyo-Young
    • Journal of the Korean Data and Information Science Society
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    • 제20권3호
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    • pp.593-599
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    • 2009
  • We consider the problem of using control charts to monitor more than one parameter with emphasis on simultaneously monitoring the mean and variance. The fixed sampling interval (FSI) control charts are modified to use variable sampling interval (VSI) control charts depending on what is being observed from the data. In general, approaches of monitoring the mean and variance simultaneously is to use separate charts for each parameter and a combined chart. In this paper, we use three basic strategies which are separate Shewhart charts for each parameter, a combined Shewhart chart and a combined CUSUM chart. We showed that a combined VSI CUSUM chart is comparatively more efficient than any other chart if the shifts in both mean and variance are small.

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공정평균을 관리하기 위한 로버스트 관리도 (Robust Control Chart for the Control of the Process Mean)

  • 이병근;정현석;남호수
    • 산업경영시스템학회지
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    • 제21권48호
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    • pp.65-71
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    • 1998
  • Control chart is a very extensively used tool in testing whether a process is in a state of statistical control or not. In this paper, a robust control chart for variables is proposed, which is based on the Huber's M-estimator. The Huber's M-estimator is a well-known robust estimator in sense of distributional robustness. In the proposed chart, the estimation of the process deviation is modified to have a stable level and high power. To compare the performances of the proposed control chart with the classical (equation omitted), some Monte Carlo simulations are performed. The simulation results show that the robust control chart has good performance.

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로버스트 지수가중 이동평균(EWMA) 관리도 (A Robust EWMA Control Chart)

  • 남호수;이병근;주철민
    • Journal of the Korean Data and Information Science Society
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    • 제10권1호
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    • pp.233-241
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    • 1999
  • 본 논문에서는 공정평균을 관리하기 위한 관리도로서 지수가중 이동평균(EWMA)관리도를 고려하였다. 기존의 표본평균에 기초한 관리도의 비로버스트성 (non-robustness)에 근거하여 공정평균의 로버스트 추정량인 M-추정량에 기초한 지수가중 이동평균 관리도를 제안하였다. 제안된 관리도의 성능을 기존의 관리도와 비교해 보기 위하여 다양한 상황에서 모의실험을 행하였으며, 실험결과 제안된 관리도의 우수성이 입증되었다.

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Pre-Control의 수행도에 관한 소고 (A Note on the Performance of Pre-Control)

  • 서순근
    • 품질경영학회지
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    • 제44권3호
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    • pp.587-600
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    • 2016
  • Purpose: This paper evaluates the performance of the pre-control(PC), an alternative to statistical process control techniques and compares with a control chart considering the tolerance of process. Methods: The previous studies for PC have drawbacks that PC with two linked stages, qualification and running, are discussed separately and independently. Hence this paper analyzes the performance of PC by integrating two stages. Results: Average outgoing quality limits to grasp the outcome of PC are provided by computational results for two process capability indexes, $C_p$ and $C_{pk}$ and the usefulness of PC from comparative experiments with modified control charts is commented. Conclusion: Helpful guidelines for quality managers to apply PC in practice and areas of process for PC to be more benefit are presented.

임의 순서 차트 파싱 알고리즘 (Random Order Chart Parsing Algorithm)

  • 심광섭
    • 한국정보과학회논문지:소프트웨어및응용
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    • 제37권6호
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    • pp.446-454
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    • 2010
  • 차트 파싱 알고리즘에서는 입력 문장의 왼쪽에서 오른쪽으로 파싱을 진행하여야 한다는 제약이 따른다. 본 논문에서는 이러한 제약을 없앤 임의 순서 차트 파싱 알고리즘을 제안한다. 제안한 알고리즘에서는 입력 문장의 각 단어에 대하여 어떤 순서로 파싱을 하더라도 무방하다. 입력 문장의 왼쪽에서 오른쪽으로 파싱을 진행하는 것은 임의 순서로 파싱을 진행하는 것의 특수한 형태이므로 임의 순서 차트파싱 알고리즘에서도 입력 문장의 왼쪽에서 오른쪽으로 파싱을 하는 것이 가능하다. 제안된 알고리즘은 차트 파싱 알고리즘을 확장한 것으로서 제어 구조가 매우 단순하며 구현도 용이하다.

A Modified Target Costing Technique to Improve Product Quality from Cost Consideration

  • Wu, Hsin-Hung
    • International Journal of Quality Innovation
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    • 제6권2호
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    • pp.31-45
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    • 2005
  • The target costing technique, mathematically discussed by Sauers, only uses the $C_p$ index along with Taguchi loss function and ${\bar{X}}-R$ control charts to set up goal control limits. The new specification limits derived from Taguchi loss function is linked through the $C_p$ value to ${\bar{X}}-R$ control charts to obtain goal control limits. This study further considers the reflected normal loss function as well as the $C_{pk}$ index along with its lower confidence interval in forming goal control limits. With the use of lower confidence interval to replace the point estimator of the $C_{pk}$ index and reflected normal loss function proposed by Spiring to measure the loss to society, this modified and improved target costing technique would become more robust and applicable in practice. Finally, an example is provided to illustrate how this modified and improved target costing technique works.