• 한국정밀공학회지
• /
• 제15권2호
• /
• pp.75-80
• /
• 1998

Process information is known to have the continuous distribution in many manufacturing processes. Generalized p-chart has been developed for controlling processes by classifying the information characteristics into several groups. But it is improper to describe continuous processes with the classified process informal ion, which is based on the classical set concept. Fuzzy control chart, has been developed for the control of linguistic data, but it is also based on the dichotomous notion of classical set theory. In this paper, fuzzy sampling method is studied in order to process the uncertain data properly. The method is incorporated with the fuzzy control chart. Statistical characteristics of the fuzzy representative value are utilized to device the fuzzy-statistical control chart. The fuzzy-statistical control chart is compared with the generalized p-chart and both the sensitivity to the process information distribution change pared robustiness against the noise on the process information of the fuzzy-statistical control chart are shown to be superior.

• 한국의류학회지
• /
• 제24권7호
• /
• pp.1044-1055
• /
• 2000

The purpose of this study is to suggest sizing chart for a clean room wear. 3 control dimensions(Stature, Bust girth, B.N.P.∼Wrist point length) were chosen as 3 axes of clean room wear size chart. A loss function was used to determined intervals of stature, Bust girth and B.N.P.∼Wrist point length of size chart, because the loss function introduces the concept of frequency to size chart for better customer's size satisfaction. From the size table whose intervals had been determined by a loss function. The 4 sizes individually were suggested for clean room wear size chart by sex. The 3 sizes individually were suggested for clean room head cover size chart by sex too. The suggested size chart would be considered more feasible than present size chart. Also they are suggested supply reference measurement chart relevant to clean room wear manufacturing for 13 most frequent sizes.

• 품질경영학회지
• /
• 제35권1호
• /
• pp.24-34
• /
• 2007

This paper investigates the average run length (ARL) of a selectively moving average (S-MA) control chart. The S-U chart is designed to detect shifts in the process mean. The basic idea of the S-MA chart is to accumulate previous samples selectively in order to increase the sensitivity. The ARL of the S-MA chart was shown to be monotone decreasing with respect to the decision length in a previous research [3]. This paper derives the steady-state ARL in a closed-form and shows that the monotone property is resulted from head-start assumption. The steady-state ARL is shown to be a sum of head-start ARL and an additional term. The statistical design procedure for the S-MA chart is revised according to this result. Sensitivity study shorts that the steady-state ARL performance is still better than the CUSUM chart or the Exponentially Weighted Moving Average (EWMA) chart.

• 산업경영시스템학회지
• /
• 제39권3호
• /
• pp.10-17
• /
• 2016

Control Chart is a graph which dots the characteristic values of a process. It is the tool of statistical technique to keep a process in controlled condition. It is also used for investigating the state of a process. Therefore many companies have used Control Chart as the tool of statistical process control (SPC). Products from a production process represent accidental dispersion values around a certain reference value. Fluctuations cause of quality dispersion is classified as a chance cause and a assignable cause. Chance cause refers unmanageable practical cause such as operator proficiency differences, differences in work environment, etc. Assignable cause refers manageable cause which is possible to take actions to remove such as operator inattention, error of production equipment, etc. Traditionally ${\bar{x}}-R$ control chart or ${\bar{x}}-s$ control chart is used to find and remove the error cause. Traditional control chart is to determine whether the measured data are in control or not, and lets us to take action. On the other hand, RNELCC (Reflected Normal Expected Loss Control Chart) is a control chart which, even in controlled state, indicates the information of economic loss if a product is in inconsistent state with process target value. However, contaminated process can cause control line sensitive and cause problems with the detection capabilities of chart. Many studies on robust estimation using trimmed parameters have been conducted. We suggest robust RNELCC which used the idea of trimmed parameters with RNEL control chart. And we demonstrate effectiveness of new control chart by comparing with ARL value among traditional control chart, RNELCC and robust RNELCC.

• 인터넷정보학회논문지
• /
• 제9권5호
• /
• pp.47-58
• /
• 2008

차트는 여러 종류의 정보를 시각적으로 표현하기 때문에 정보 전달력이 높다. 이런 이유로 웹 개발자들도 정보를 표현할 때 차트를 자주 활용한다. 그러나 차트를 활용하기 위해서는 차트를 작성하는 전용 프로그램이 필요하며, 작성된 차트도 일반적으로 래스터 방식의 이미지로 표현되기 때문에 차트정보를 공유하기 어렵다. 이러한 래스터 방식의 이미지는 이미지의 크기가 고정되기 때문에 이미지의 크기를 변경하면 이미지가 왜곡된다는 문제점이 발생한다. 본 논문에서는 차트정보의 호환성과 차트정보의 공유 문제를 해결하기 위해 CML(Chart Markup Language)을 이용한 웹 기반의 차트출력시스템을 제안한다. 본 논문에서 제안한 차트출력시스템은 XML, Text, HTML 문서를 분석하여 차트정보를 추출한 후, 추출한 차트정보를 CML로 변환하고, 변환된 CML문서를 벡터 방식을 이용하여 차트를 웹브라우저에 출력한다. 벡터 방식은 이미지를 표현할 때 벡터를 활용하기 때문에 이미지의 크기가 변경되더라도 이미지가 깨지거나 왜곡되는 현상이 없다는 장점이 있다. 본 논문에서 제안한 CML은 차트정보를 표현하기 위해 정의한 XML 기반의 차트생성언어이다. 웹에서 차트를 표현할 때 CML을 활용하면 차트정보를 쉽게 공유할 수 있으며, 차트정보 변환이 수월하다는 장점이 있다.

• 해양환경안전학회지
• /
• 제17권2호
• /
• pp.137-142
• /
• 2011

지난 60년간 급속한 항만 개발로 인하여 다량의 해도가 여러 종류의 축척 및 구역으로 제작되어 인접구역이 효과적으로 연결되지 못하거나 과도한 중첩 구역이 발생하는 경우가 있으며 무리한 제분도의 사용으로 이용자에게 혼란 및 불편을 야기하고 있는 실정이다. 이 연구의 목적은 대한민국에서 간행되는 해도의 구역 및 축척별 분석을 통하여 새로운 해도구역 조정안을 제시하는데 있으며 이를 통해 항해 편의를 제공하는데 있다. 합리적인 해도구역 조정을 위하여 연구진이 전문가 의견법을 통하여 개정안을 마련한 후 이용자를 대상으로 한 설문조사 및 도선구역별 도선사 협회의 의견 수렴 등을 통하여 그 타당성을 검증받고 의견을 수렴하여 보완하였다. 연구의 결과로 현재 간행되고 있는 309장의 해도는 334장으로 변경되었다.

• 품질경영학회지
• /
• 제33권3호
• /
• pp.126-134
• /
• 2005

This paper proposes a selectively cumulative sum(S-CUSUM) control chart for detecting shifts in the process mean. The basic idea of the S-CUSUM chart is to accumulate previous samples selectively in order to increase the sensitivity. The S-CUSUM chart employs a threshold limit to determine whether to accumulate previous samples or not. Consecutive samples with control statistics out of the threshold limit are to be accumulated to calculate a standardized control statistic. If the control statistic falls within the threshold limit, only the next sample is to be used. During the whole sampling process, the S-CUSUM chart produces an 'out-of-control' signal either when any control statistic falls outside the control limit or when L -consecutive control statistics fall outside the threshold limit. The number L is a decision variable and is called a 'control length'. A Markov chain approach is employed to describe the S-CUSUM sampling process. Formulae for the steady state probabilities and the Average Run Length(ARL) during an in-control state are derived in closed forms. Some properties useful for designing statistical parameters are also derived and a statistical design procedure for the S-CUSUM chart is proposed. Comparative studies show that the proposed S-CUSUM chart is uniformly superior to the CUSUM chart or the Exponentially Weighted Moving Average(EWMA) chart with respect to the ARL performance.

• Journal of the Korean Data and Information Science Society
• /
• 제26권3호
• /
• pp.729-738
• /
• 2015

품질특성치의 중심과 산포를 하나의 통계량으로 관리하는 단일 관리도는 품질특성치가 정규분포를 따른다고 가정하지만 실제 데이터들은 왜도가 양수이거나 첨도가 양수인 경우가 많다. 본 논문에서는 품질특성치가 정규분포를 따르지 않은 경우에 가짜 알람률 (false alarm rate; FAR)을 이용하여 단일 관리도 성능을 비교하였다. 고려된 단일 관리도는 반원관리도, 최대 관리도 및 평균제곱오차관리도이며 모의실험 결과, 공정이 안정 상태인 경우는 최대관리도의 성능이 좋았으며, 공정이 불안정상태인 경우에는 왜도가 양수일 때 최대관리도, 첨도가 큰 경우에는 평균제곱오차 관리도의 성능이 우수하였다.

• Communications for Statistical Applications and Methods
• /
• 제5권2호
• /
• pp.373-381
• /
• 1998

In this paper a new control chart which accounts for correlation between process subgroups will be proposed. We consider the case where the process fluctuations are autocorrelated by a stationary AR(1) time series and where n($\geq1$) items are sampled from the process at each sampling time. A simulation study is presented and shows that for correlated subgroups, the proposed control chart makes a significant improvement over the traditionally employed X-bar chart which ignores subgroup correlations. Finally, we illustrate the proposed chart by comparing the standardized residuals and X-bar chart on a data set of motor shaft diameters.

• Journal of the Korean Data and Information Science Society
• /
• 제26권4호
• /
• pp.997-1006
• /
• 2015

In industrial quality control, when engineers use VSI control procedure they should consider both required time to signal and switching behaviors together in the case of production process changed. Up to the present, many researchers have studied fixed sampling interval (FSI) chart and variable sampling interval (VSI) chart in the points of average number of samples to signal (ANSS) and average time to signal (ATS). However, ANSS and ATS do not provide any switching information between different sampling intervals of VSI schemes. In this study, performances of two sampling intervals VSI chart and three sampling intervals VSI chart are evaluated and compared. The numerical results show that ANSS and ATS values of two sampling intervals VSI chart and three sampling interval VSI chart are similar regardless the amount of shifts. However, the values of switching behaviors including ANSW are less efficient in three sampling intervals VSI charts than in two sampling intervals VSI chart.