In recent years, supply chain risk management has become a hot research topic for researchers and practitioners. A diamond style supply chain, which is characterized by one parts supplier providing its parts to many companies and finally deliver to many assemblers, was identified in the manufacturing industry in Japan after the March 11 disaster in 2011, To prevent indirect loss from the supply chain disruption, Japanese companies are now collecting information of the supplier's supplier, so as to enable visualization of the physical flow of materials in the supply chain. In this research, we propose a method which we call the Supply Chain Visualization System (SCVS), which enables visualization of the supply network and validation of the usefulness of the method through roleplaying experiments using a simple three stages simple supply chain. Through the experiments, we found that the down stream companies in the supply chain are able to increase profits utilizing the SCVS as the result of proper decisionmaking regarding procurement. Interestingly, those companies that believed they do not have relationship with the disrupted company also reported an increase in profit. They benefited from the agile response of the final product assembler to the supply chain disruption, which assures continuous operation. Therefore, all suppliers except the disrupted supplier were able to continue production and maintain profitability. Furthermore, to mitigate supply chain disruption risks, three strategies, such as redundancy, robustness and flexibility, and two combinations of the three strategies were tested in three different business environments. We found that the strategy that enhances system redundancy (increased safety stock level) is not the best option under some system condition such as the conditions set in this research. From the simulation, we concluded that the best strategy to mitigate supply chain disruption depends on the system conditions.

Recently, it is important for manufacturing companies to shorten pre-production processes. In the overall process, determination of the optimum assembly sequence is one of the important tasks. However, it is actually selected by some experienced engineers from limited assembly sequences. This paper presents the concept of an exhaustive assembly sequences derivation method based on the positional relations matrix. The exhaustive derivation of the sequences needs to determine all of the intermediate products in the assembling processes. This paper therefore presents an efficient and exhaustive derivation method for intermediate products by disassembling finished or intermediate products. Additionally, the way to list assembly sequences from the intermediate products is shown. The presented method is applied to two products of 13 parts and 24 parts, respectively, and the effectiveness is tested.

In recent years, information systems are essential to decide management for an enterprise. In the information systems of an enterprise, one management problem is that cost of maintenance processes for the information system become larger than the development process of the information system itself. As one cause of this management problem, there are many inquiries in the initial failure period after operating the information system. In general, there are many times to correspond to many inquiries because the inquiries are not able to forecasted. In previous studies, there have been some studies regarding factors that lead to the occurrence of inquiries, but these factors have not been clarified. In this paper, factors of the inquiries that occur are estimated by cluster analyzing contents data, time and the number of cases of bugs. From this estimation, a forecasting model that includes inquiries of bugs occurring is proposed. Moreover, information sheets are proposed to introduce the proposed forecasting model to the development field of information systems.