Koji Okuhara

Optimal control of inventory systems with multiple suppliers

In this paper, efficient inventory management is addressed. The considered system has multiple suppliers with lead-time, and the order rate to each supplier is time-varying. Also, the demand is unknown and time-varying. Then the optimal regulator theory is employed. The derived rule of order quantity reduces the deviation from the target stock level and the order cost.

Factor Analysis for Employment using Student Information Data

For students, one of the goals to enter into a university is to be able to get a job at a good company. Various entrance examinations are offered to students from high school to enter into the university. Then, receiving a lecture at a university, acquiring a unit, assigning to a seminar and preparing a graduation thesis. After graduating from university, most students find employment in companies, which makes possible to acquire various data in a series of flows from high school graduation to employment. This research analyzes how a set of factors such as deviation value of the senior high school, type of entrance examination, achievement of the University, seminar advisor, and the employment place data can influence this process. Moreover, the paper considers the analysis of variance for the same purpose.

Mass Customization Production Planning System by Advance Demand Information Based on Unfulfilled-order-rate: II-Performance Analysis of Unfulfilled-order-rates and Relationship to Base-stock Policy with Multi-period

In the previous paper, we proposed Mass Customization Production Planning & Management System (MCPS) based on unfulfilled-order-rate by using Advance Demand Information which is called ‘Naiji System’ as an unique corporation between a maker and suppliers in Japan, and 3 indicators to estimate the unfulfilled-order-rate. Applying these indicators to the model, we investigated the behavior of unfulfilled-order-rate at the final period in the planning horizon. In this paper, we propose a new model for purchasing, and investigate the unfulfilled-order-rate at each period and the impact to the total inventory. We find that the total inventories become 5.9%-20.0% decreases by using SOn rather than by using SOn(0). And we enhance a base-stock policy to a new one with multi-period. We prove that the MCPS model for purchasing by using SOn(0) is equivalent to the base-stock policy with multi-period under the specified condition. Under this condition, the proposed model by using SOn decreases inventories more than the base-stock policy with multi-period.