• Journal of Korean Society for Quality Management
• /
• v.33 no.1
• /
• pp.1-10
• /
• 2005

This paper develops a new VSI $\={X}-CRL$ synthetic control chart that considers convenience of use in the field, and perception of change of process applying VSI techniques to synthetic control chart, simultaneously. We found the optimal sampling interval and various control limit factor of the suggested chart using markov chain. Comparison and analysis is carried out between synthetic VSI $\={X}-CRL$ chart and other chart in the statistical aspect; $\={X}$ control chart, VSI $\={X}$ chart, another synthetic chart. In case that the process follows normal distribution, the proposed VSI $\={X}-CRL$ synthetic control chart in detecting process mean shift showed the best performance in aspect of statistical performance, regardless of control limit L of CRL/S control chart.

• Proceedings of the Safety Management and Science Conference
• /
• 2010.04a
• /
• pp.253-258
• /
• 2010

The paper reviews the methodologies of confirmatory data analysis(CDA) and exploratory data analysis(EDA) in statistical quality control(SQC), design of experiment(DOE) and reliability engineering(RE). The study discusses the properties of flexibility, openness, resistance and reexpression for EDA.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.16 no.28
• /
• pp.173-180
• /
• 1993

This paper is to propose the procedure for improving the level of product specification in statistical process control using loss function. The procedure proposed in this paper is extended to the Taguchi's Quality engineering concept This procedure will be useful in establishing product specification. This paper is aimed to provide customer satisfaction for consumer and quality management for producer.

• The Korean Journal of Applied Statistics
• /
• v.1 no.1
• /
• pp.29-38
• /
• 1987

This article deals with statistical quality control (SQC) activities in manufacturing processes, First of all, the sources of variatin in product quality are listed and studied. Next, a typical SQC activity system in manufacturing processes is provided with a flow-chart, and each step in the system is explained. A real case example of a domestic company which follows the SQC activity system is illustrated. Finally, some approaches to activate SQC in manufacturing companies are suggested.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.116.3-116
• /
• 2001

A diagnosis methodology for thickness quality in hot finishing mill is proposed based on multivariate statistical analysis. The thickness of hot strip is a key quality factor that is measured by x-ray thickness gauge. Currently, the thickness quality is guaranteed by upper and lower limit of thickness deviation from target thickness. But if any over-limit is occurred, there is no in-line method to identify the causes. In this paper, many parameters are extracted from the thickness deviation signal such as mean deviation(top, middle, tail), rms deviation(top, middle, tail) and peak deviation(top, middle, tail) as time domain parameters ...

• The Journal of the Korea Contents Association
• /
• v.16 no.6
• /
• pp.529-536
• /
• 2016

The purpose of this research is to evaluate the quality of Differential Police Response strategy. Although it has been approximately three years since these new police response systems were introduced, there is no research to evaluate them empirically. Using two types of statistical quality control techniques, Xbar-R control charts for variables data and P charts for attributes data, this study analyzes approximately 3,000 calls reported throughout the year 2012 to the 112 Integrated Dispatch Center in Ik-san police station. The Xbar-R control charts revealed that the police did not consistently respond to an emergency call for service (i.e., code one case) within 3 minutes. The P control chart also identified that there was a significant variation in the portion/number of defective calls where police failed to respond to non-emergency calls for service within 5 minutes. The results from this study suggest the police may need to review the target response time for code 1 and code 2 respectively.

• International Journal of Quality Innovation
• /
• v.4 no.1
• /
• pp.46-53
• /
• 2003

Under the strong leadership of Chinese Government to the anti-SARS struggle, the situation has been successfully controlled. Since May 1 of 2003, the Ministry of Health of China published daily the number of newly increased SARS patient of Beijing, the authors analyzed these data using $X_cs$$-R_scs$ cause-selecting control charts of Statistical Diagnosis(SPD) Theory. Data about number of newly increased SARS patient consists of two kinds of variation: random variation and tendency variation of SARS epidemic. It is concluded that SARS epidemic of Beijing was already controlled since May 9 of 2003.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.30 no.2
• /
• pp.99-105
• /
• 2007

According to the automated manufacturing processes followed by the development of computer manufacturing technologies, products or quality characteristics produced on the processes have measured and recorded automatically. Much amount of data daily produced on the processes may not be efficiently analyzed by current statistical methodologies (i.e., statistical quality control and statistical process control methodologies) because of the dimensionality associated with many input and response variables. Although a number of statistical methods to handle this situation, there is room for improvement. In order to overcome this limitation, we integrated data mining and robust design approach in this research. We find efficiently the significant input variables that connected with the interesting response variables by using the data mining technique. And we find the optimum operating condition of process by using RSM and robust design approach.

• Journal of Korean Society for Quality Management
• /
• v.12 no.2
• /
• pp.15-24
• /
• 1984

Since W.A. Shewhart (1931) developed the quality control method using the control chart, many theoretical and empirical works about such an analytical method have been done. However there are two major methods relating to the control chart analysis; the conventional 3 sigma control method and the warning limit method which has been suggested as a modification of the former. The conventional 3 sigma method requires to take a remedial action only when a quality characteristic is beyond the control limit (3 sigma). However, once a quality characteristic is over the control limit, searching and repairing an assignable cause requires time consuming job and high costs. Therefore if we set the warning limit between the central line and the control limit, we will be able to take remedial measures before too late. In spite of its advantage, much attention has not been paid to use the control chart with warning limit in Korean industries. The main object of this study is to examine improvement of quality and productivity when the control chart with warning limit is used.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.25 no.4
• /
• pp.1-7
• /
• 2002

Statistical process control is used widely as an effective tool to solve the quality problems in practice fields. All the control charts used in statistical process control are parametric methods, suppose that the process distributes normal and observations are independent. But these assumptions, practically, are often violated if the test of normality of the observations is rejected and/or the serial correlation is existed within observed data. Thus, in this study, to screening process, the Combined Shewhart - CUSUM quality control chart is described and evaluated that used bootstrap method. In this scheme the CUSUM chart will quickly detect small shifts form the goal while the addition of Shewhart limits increases the speed of detecting large shifts. Therefor, the CSC control chart is detected both small and large shifts in process, and the simulation results for its performance are exhibited. The bootstrap CSC control chart proposed in this paper is superior to the standard method for both normal and skewed distribution, and brings in terms of ARL to the same result.