• Title/Summary/Keyword: 다변량 관리도

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Multivariate Shewhart control charts with variable sampling intervals (가변추출간격을 갖는 다변량 슈하르트 관리도)

  • Cho, Gyo-Young
    • Journal of the Korean Data and Information Science Society
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    • v.21 no.6
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    • pp.999-1008
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    • 2010
  • The objective of this paper is to develop variable sampling interval multivariate control charts that can offer significant performance improvements compared to standard fixed sampling rate multivariate control charts. Most research on multivariate control charts has concentrated on the problem of monitoring the process mean, but here we consider the problem of simultaneously monitoring both the mean and variability of the process.

A readjustment procedure in the multivariate integrated process control (다변량 통합공정관리에서 재수정 절차)

  • Cho, Gyo-Young;Park, Jong-Suk
    • Journal of the Korean Data and Information Science Society
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    • v.22 no.6
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    • pp.1123-1135
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    • 2011
  • This paper considers the multivariate integrated process control procedure for detecting special causes in a multivariate IMA(1, 1) process. When the multivariate control chart signals, the special cause will be detected and eliminated from the process. However, when the elimination of the special cause costs high or is not practically possible, an alternative action is to readjust the process with approximately modified adjustment scheme. In this paper, we propose the readjustment procedure after having a true signal, and show that the use of the readjustment can reduce the deviation of a process from the target.

Parameter estimation in a readjustment procedure in the multivariate integrated process control (다변량 통합공정관리의 재수정 절차에서 모수추정)

  • Cho, Gyo-Young;Park, Jong Suk
    • Journal of the Korean Data and Information Science Society
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    • v.24 no.6
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    • pp.1275-1283
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    • 2013
  • This paper considers the multivariate integrated process control procedure for detecting special causes in a multivariate IMA(1, 1) process. When the multivariate control chart signals, the special cause will be detected and eliminated from the process. However, when the elimination of the special cause costs high or is not practically possible, an alternative action is to readjust the process with approximately modified adjustment scheme. In this paper, we estimate parameters in the readjustment procedure after having a true signal in the multivariate integrated process control.

Detection of the Change in Blogger Sentiment using Multivariate Control Charts (다변량 관리도를 활용한 블로거 정서 변화 탐지)

  • Moon, Jeounghoon;Lee, Sungim
    • The Korean Journal of Applied Statistics
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    • v.26 no.6
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    • pp.903-913
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    • 2013
  • Social network services generate a considerable amount of social data every day on personal feelings or thoughts. This social data provides changing patterns of information production and consumption but are also a tool that reflects social phenomenon. We analyze negative emotional words from daily blogs to detect the change in blooger sentiment using multivariate control charts. We used the all the blogs produced between 1 January 2008 and 31 December 2009. Hotelling's T-square control chart control chart is commonly used to monitor multivariate quality characteristics; however, it assumes that quality characteristics follow multivariate normal distribution. The performance of a multivariate control chart is affected by this assumption; consequently, we introduce the support vector data description and its extension (K-control chart) suggested by Sun and Tsung (2003) and they are applied to detect the chage in blogger sentiment.

Multivariate process control procedure using a decision tree learning technique (의사결정나무를 이용한 다변량 공정관리 절차)

  • Jung, Kwang Young;Lee, Jaeheon
    • Journal of the Korean Data and Information Science Society
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    • v.26 no.3
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    • pp.639-652
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    • 2015
  • In today's manufacturing environment, the process data can be easily measured and transferred to a computer for analysis in a real-time mode. As a result, it is possible to monitor several correlated quality variables simultaneously. Various multivariate statistical process control (MSPC) procedures have been presented to detect an out-of-control event. Although the classical MSPC procedures give the out-of-control signal, it is difficult to determine which variable has caused the signal. In order to solve this problem, data mining and machine learning techniques can be considered. In this paper, we applied the technique of decision tree learning to the MSPC, and we did simulation for MSPC procedures to monitor the bivariate normal process means. The results of simulation show that the overall performance of the MSPC procedure using decision tree learning technique is similar for several values of correlation coefficient, and the accurate classification rates for out-of-control are different depending on the values of correlation coefficient and the shift magnitude. The introduced procedure has the advantage that it provides the information about assignable causes, which can be required by practitioners.

Establishing a Early Warning System using Multivariate Control Charts in Melting Process (용해공정에서 다변량 관리도를 이용한 조기경보시스템 구축)

  • Lee, Hoe-Sik;Lee, Myung-Joo;Han, Dae-Hee
    • Journal of the Korea Society of Computer and Information
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    • v.12 no.4
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    • pp.201-207
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    • 2007
  • In some manufacturing industries, there are many situation in which the simultaneous monitoring or control of two or more related quality characteristics is necessary. However, monitoring these two or more related quality characteristics independently can be very misleading. When several characteristics of manufactured component are to be monitored simultaneously, multivariate $x^2$ or $T^2$ control chart can be used. In this paper, establishing a early warning system(EWS) using multivariate control charts to analyze early out-of-control signals in melting process with many quality characteristics was presented. This module which we developed to control several characteristics improved efficiency and effectiveness of process control in the melting process.

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Notes on identifying source of out-of-control signals in phase II multivariate process monitoring (다변량 공정 모니터링에서 이상신호 발생시 원인 식별에 관한 연구)

  • Lee, Sungim
    • The Korean Journal of Applied Statistics
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    • v.31 no.1
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    • pp.1-11
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    • 2018
  • Multivariate process control has become important in various applied fields. For instance, there are many situations in which the simultaneous monitoring of multivariate quality characteristics is necessary for the manufacturing industry. Despite its importance, its practical usage is not as convenient because it is difficult to identify the source of the out-of-control signal in a multivariate control chart. In this paper, we will introduce how to detect the source of the out-of-control by using confidence intervals for new observations, and will discuss the identification and interpretation of the out-of-control variable through simulation studies.

On multivariate GARCH model selection based on risk management (리스크 관리 측면에서 살펴본 다변량 GARCH 모형 선택)

  • Park, SeRin;Baek, Changryong
    • Journal of the Korean Data and Information Science Society
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    • v.25 no.6
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    • pp.1333-1343
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    • 2014
  • Hansen and Lund (2005) documented that a univariate GARCH(1,1) model is no worse than other sophisticated GARCH models in terms of prediction errors such as MSPE and MAE. Here, we extend Hansen and Lund (2005) by considering multivariate GARCH models and incorporating risk management measures such as VaR and fail percentage. Our Monte Carlo simulations study shows that multivariate GARCH(1,1) model also performs well compared to asymmetric GARCH models. However, we suggest that actual model selection should be done with care in light of risk management. It is applied to the realized volatilities of KOSPI, NASDAQ and HANG SENG index for recent 10 years.

Identification of the out-of-control variable based on Hotelling's T2 statistic (호텔링 T2의 이상신호 원인 식별)

  • Lee, Sungim
    • The Korean Journal of Applied Statistics
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    • v.31 no.6
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    • pp.811-823
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    • 2018
  • Multivariate control chart based on Hotelling's $T^2$ statistic is a powerful tool in statistical process control for identifying an out-of-control process. It is used to monitor multiple process characteristics simultaneously. Detection of the out-of-control signal with the $T^2$ chart indicates mean vector shifts. However, these multivariate signals make it difficult to interpret the cause of the out-of-control signal. In this paper, we review methods of signal interpretation based on the Mason, Young, and Tracy (MYT) decomposition of the $T^2$ statistic. We also provide an example on how to implement it using R software and demonstrate simulation studies for comparing the performance of these methods.

Integrated Procedure of Self-Organizing Map Neural Network and Case-Based Reasoning for Multivariate Process Control (자기조직화 지도 신경망과 사례기반추론을 이용한 다변량 공정관리)

  • 강부식
    • Journal of Intelligence and Information Systems
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    • v.9 no.1
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    • pp.53-69
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    • 2003
  • Many process variables in modem manufacturing processes have influence on quality of products with complicated relationships. Therefore, it is necessary to control multiple quality variables in order to monitor abnormal signals in the processes. This study proposes an integrated procedure of self-organizing map (SOM) neural network and case-based reasoning (CBR) for multivariate process control. SOM generates patterns of quality variables. The patterns are compared with the reference patterns in order to decide whether their states are normal or abnormal using the goodness-of-fitness test. For validation, it generates artificial datasets consisting of six patterns, normal and abnormal patterns. Experimental results show that the abnormal patterns can be detected effectively. This study also shows that the CBR procedure enables to keep Type 2 error at very low level and reduce Type 1 error gradually, and then the proposed method can be a solution fur multivariate process control.

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