| Summary: | 碩士 === 國立交通大學 === 工業工程與管理學系 === 100 === Control Chart is one of the most important tools in statistical process control (SPC). Among many types of control charts, the most often used one is X bar chart. When using X bar chart, the values of sample size(n), sampling interval(h) and coefficient of control limit(k) must be determined. Some studies have developed the economic design and economic-statistical of X bar chart with multiple assignable causes in the process. The economic design or economic-statistical design can determine the optimal values of (n, h, k) with lowest cost. However, these methods did not consider that different values of a quality characteristic of a product may have different effects on customers’ loss. Therefore, this study proposes an revised economic-statistical design of X bar chart with multiple assignable causes in the process using Taguchi’s loss function. After constructing the economic-statistical design, genetic algorithm (GA) is utilized to determine the values of (n, h, k) in the proposed model and sensitivity analysis is carried out to study the effect of the parameters in the proposed model. The results showed that if quality loss is an important index, then the proposed economic-statistical design is better than the developed methods in previous studies in terms of total cost per unit time. Additionally, the most sensitive parameter of the proposed economic-statistical design is the amount of shift in means by certain assignable cause.
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