DEVELOPMENTS OF DESIGNING METHOED OF CONTROL CHART TO ENHANCE DETECTION POWER IN HIGH-YIELD PROCESSES

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In this research project, two study subjects have been mainly approached and the research findings have been obtained between 2002 and 2004 by Professor Ohta and Research Associate Kusukawa. 1. Design of control chart to detect sensitively small or moderate shifts toward any directions, which indicate the process deterioration and the process improvement, in the process mean obtained from small size of subgroups, the process fraction defectives or the process defect rate in high-yield processes and actualize almost a specified value of type I error of quality characteristics mentioned above. Our proposed control charts would be useful highly as alternative control charts of the Shewhart types charts such as X^^-R chart, p chart and c chart (See REFERENCES 1, 2, 3, 5, 6, 7, 9, 11, 12 and 13.). 2. Economic design of control chart developed in above study subject 1. to maximize the system profit per unit time of process cycle or to minimize system cost per unit time of process cycle under various process situations such as dynamic process where the process failure rate is varying over time. Our proposed-economic designing methods would be useful highly when it is required to run a high-yield process economically by using our proposed control charts in above study subject 1.. (See REFERENCES 4, 8 and 10.). As the future Research work, based on REFERENCES 1 and 6, the Synthetic EWMA chart that is integration of the CCC-r chart and the EWMA_<CCC-r> chart in REFERENCE 13 could be designed. It is expected that the Synthetic EWMA chart constructed from time-series data would be more sensitive to monitor the process defective rate than the Synthetic CS chart. As the further future Research work, based on REFERENCES 4, 8 and 10, an economic design of the Synthetic EWMA chart under dynamic process could be developed.