Major studies on cell production have placed an emphasis on technical factors such as machine order/layout, family part grouping, work-flow sequence, etc. However, there have still been insufficient investigations as to how workers' aptitudes affect their performance in production cells. Intending to find the worker's aptitude closely relating to her/his performance in cell production, we design a laboratory experiment, and administer 11 paper-and-pencil tests of the Japanese General Aptitude Test Battery (GATB) to the workers and measure their seven work-related aptitudes. We pay special attention to detecting outliers in the GATB scores and the cell production experiment results, and then examine the partial correlations between the workers' GATB scores and their performance. As the GATB scores can't directly measure a worker's aptitude towards the assembly tasks in production cells, we make use of principal component analysis and obtain a component score that correlates significantly with the workers' performance in cell production. As the result, we can apply this component score to measure a worker's aptitude towards the assembly tasks in cell production.
The expected number of failed components in a failed or working system might be useful for understanding the behavior of the system. This paper studies the distributions and expected values of the number of failed components for coherent systems. We first study the number of failed components in a failed system. Furthermore, we obtain the expected number of failed components when the system undergoes maintenance at a particular time. These results might be useful for understanding the behavior of the system and give an idea as to how many spare components should be available in order to replace failed components. We also present illustrative results of the expected number of failed components for well-known general coherent systems such as a bridge structure system and a consecutive-k-out-of-n:F system, and analyze the relationship among these values.
Demands of daytime care facilities that offer nursing care services are increasing in Japan because of the aging population. In these facilities, rehabilitation services such as physical therapy and exercises using equipment are offered with the staff's support. These services are offered based on a staff schedule planned by managers. Accordingly, it has become clear that facility staff members have experienced large amounts of work, labor shortages and feel the physical workload depending on the type of service. However, how staff members feel about their workload has not been considered when planning work schedules since Industrial Engineering (IE) procedures are not commonly followed in actual facilities. This study proposes a staff scheduling model and work allocation in elderly daytime care facilities considering the physical workload placed on staff. First, in order to analyze the physical workload experienced by the staff, a questionnaire and interview surveys are carried out. Next, staff scheduling in the facility is modeled, and a schedule for balancing the physical workload among staff members is planned in a numerical experiment based on the results of the workload survey. Finally, the impact of the schedule proposed is discussed by comparing it with the current schedule.