Managing the trade-off between achieving a stable production scheduling and being responsive to change in market requirements is a critical issue in production planning and scheduling. This paper analyzes the relationship between the timing of replanning and the buffer inventory in terms of system performance in the multi-stage production system. Two performance measures were used : the unfilled rate for market demand and the changed rate in production quantity. The results are obtained from simulation studies of multi-product with stochastic demand.

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Conjoint analysis is a decompositional method that estimates the structure of a consumer's preference, given his or her overall evaluations of a set of alternatives that are prespecified in terms of different attribute levels. We proposed the optimal product-planning for new multiattribute products based on the utility values of attribute levels measured by the conjoint analysis. The method is useful for a set of new multiattribute products which had different attribute levels. This paper alms to present a new product design model for the market entry of new products and the product line extension in market. That is, we present a heuristic design method for new multiattribute product using the relative utility values with respect to the most currently preferred product in consumers evoked set. Furthermore, illustrative example shows how the proposed approach can be applied.

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We investigate the impact of order-release strategies in job shop environments over a range of work flow conditions. The order-release mechanism determines which order should be released from the order pool and when it should be released to the shop for processing. Two typical opposing strategies for release timing are studied. One is a pull-type strategy that recognizes the job shop as a full work system, such as the just-in-time system. The other is a push-type strategy based on Input/Output control, such as the MRP system. For selection of order to be released, three typical strategies are considered : the FCFS rule, the WINQ rule, the SLACK rule. The two-stage system consisting of an order pool and shop floor, which controls the capacity for each period based on the backlog in the pool, is presented. The six possible combinations of strategies are compared at the same machine utilization level, taking the lead time and the percentage of tardy orders as performance criteria. The results provide a basis for disign of shop floor control systems in various manufacturing situations.

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This paper presents a mathematical model for a JIT production system with AGVs (Automated Guided Vehicles). The model treats return ways, several dispatching rules and services on Erlang distribution as well as finite buffers. The accuracy of the model is investigated by comparing through simulation. Furthermore the behavior of the machine utility rate is studied in relation with varying layouts and dispatching rules.

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In order to help elderly workers learn new skills, it is important to consider their psychological characteristics. This study focuses on task cognition as one of the psychological aspects. This paper investigates the relationship between the task cognition and performances like the learning speed or operation time in the learning process. Age differences in this relationship were also investigated. Experiments were carried out with both young and elderly subjects doing a data input task on personal computers. The result shows that the level of task cognition and correlation between task cognition and performances are different according to ages, and significantly influenced by the educational program.

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A machining center can successively process a variety of parts by exchanging tools automatically. Each part requires a different set of tools. All of required tools have to be installed in the tool magazine before the part is processed. If some required tools are not installed, the machining center have to be shut down for a setup. An optimal parts grouping problem considered here is to find an optimal partition of set of parts giving a minimum number of setups. This study proposes an optimization algorithm of the problem based on the branch and bound method.

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