In ubiquitously connected societies, students can receive education without restrictions of time or space. One example of this is e-learning, which has taken on a role to complement conventional forms of education. Business games (BG) can now be conducted online as well as in the conventional style. For this reason, there is a need for an empirical study regarding online BG, which can be used as a reference material for companies and educational institutions trying to introduce online BG. The aim of this paper is to investigate the educational effects of online BG using causality analysis based on structural equation models. Specifically, the study aims to statistically confirm whether or not the use of online BG directly contributes to the comprehension of financial statements.

View full abstract

In field activities where workers are seated, workers needed to stand up repeatedly to prevent local fatigue. However, there is concern that the act of standing up puts stress on the lower limbs due to the heavy load exerted. Therefore, we consider the installation of a handrail to ease the load on workers. In this study, we focused on physical strain during the act of standing up, and aimed to assess the effect of a low-back chair and the load dispersion effect of a handrail quantitatively. We examined physical strain while ten subjects stood up from chairs with heights of 20 or 40cm. The experimental factors included two chair heights, three anteroposterior positions of the handrail, and with or without the handrail, for a total of eight conditions. We measured the handrail-manipulation force, the floor reaction force, and performed electromyograms and subjective assessments. The results show that standing up from 20-cm-high chairs increases the strain on workers significantly. In particular, the load on the lower limbs on the opposite side to the handrail were decreased approximately six percent, although load on the upper limbs increased.

View full abstract

Laying out objects via manual handling requires upper limb work with repeated carrying and grasping of objects. It is important to clarify the factors influencing work load because repetitive upper limb work causes damage to hands, arms and shoulders. There are many studies related to repetitive upper limb work, but most of them relate to production line work in industry. In addition, there are few studies on the effect of the object shape. The shape of an object may affect how it is grasped. In this study, we therefore intended to clarify the effect of the object shape and work height on upper limb load. In this experiment, ten healthy male subjects were asked to carry objects placed on a shelf using combinations of three object shape conditions and two work height conditions. We used a can, book and fruit to simulate the object shape condition, and eye height and waist height for the work height condition. The widths of the can, book and fruit were 64, 32 and 100mm, respectively. The grasp force and muscle activity were used as evaluation indices. We also investigated subjective indices for burden, difficulty of the task and difficulty of grasping the object. Electromyography was performed at the flexor digitorum superficialis muscle, the extensor digitorum muscle, the biceps brachii muscle, the middle part of the deltoideus muscle, and the upper part of the trapezius muscle. The results showed that grasp force and its distribution were different depending on object shape, and muscular load on the shoulder joint varied depending on work height.

View full abstract

The quality of lots has sometimes been evaluated based on attribute properties such as the proportion or number of non-conforming items in the lot. There are two kinds of attribute sampling inspection plans with screening, called lot tolerance percent defective (LTPD) inspection and average outgoing quality limit (AOQL) inspection. These sampling inspection schemes have been designed in order to minimize the average total inspection (ATI), which means the expectation of number of samples to be inspected in the case of acceptance and number of samples inspected in the case that the lot is rejected. Taguchi proposed a concept of quality loss as a measure to evaluate the quality of items based on variable properties instead of attribute qualities such as the proportion of non-conforming items. This variable quality evaluation measure is known as "Taguchi's quality loss." Arizono et al. proposed acceptance sampling plans based on operating characteristics from the viewpoint of ensuring Taguchi's quality loss. Furthermore, Takemoto and Arizono proposed variable sampling inspection plans with screening for the purpose of ensuring the upper limit of maximum expected surplus loss after inspection indexed by Taguchi's quality loss. However, in the variable sampling inspection plans with screening considered in the above articles, minimizing the ATI in the screening sampling scheme has not been considered. In this article, we present design procedures for new variable sampling inspection plans with screening indexed by Taguchi's quality loss for the purpose of minimizing the ATI in conformity with conventional LTPD and AOQL attribute sampling inspection plans with screening.

View full abstract

In today's society, there is extremely keen competition among manufacturing enterprises. Under such circumstances, it is vital for these enterprises to meet the delivery date deadlines. Under uncertain conditions, the result or efficiency of a period is often controlled not only by the risks of this period, but also by the risks generated beforehand. This kind of problem is called the limited-cycle problem with multiple periods. In this research, the issue of minimum expected risk in a certain period will be discussed, assuming that risk appears in multiple periods repeatedly. This paper considers the rules for an optimal arrangement with minimum total expected risk in a limited-cycle scheduling problem with multiple periods. Firstly, we consider the situation involving two kinds of workers who have different processing efficiencies. In this situation, we propose the properties of optimal arrangement where there is one special worker who has special processing efficiency. Secondly, the properties are proven mathematically. Finally, we reveal the unknown part through numerical experiments. This paper is significant as one step to derive the optimal arrangement theoretically.

View full abstract