Today, the problems that all manufacturers face is how to shorten manufacturing lead time, and manufacturers that adopt make-to-order production systems have to make products whose specifications differ with each order. In such a situation, an efficient production planning and control system is required. The function of scheduling is to plan and control the flow of order from its arrival to its completion. Generally, the scheduling system is hierarchically composed of several sub-systems. The number of hierarchies differs according to the size of the company and the complexity of the products the company manufactures. However, it is necessary for the scheduling system to have the following four sub-systems at least. First of all, an upper sub-system that screens the order and determines its due date. A master schedule is then drafted by a subsequent sub-system. Next, master schedule is broken down into a detailed schedule by yet another sub-system. Lastly, operations are dispatched to appropriate workstations by the lowest level sub-system. In this study, we focus our attention on the master schedule. This master schedule is drafted by loading. One of the problems on loading is that the method to set the optimum bucket size is not made clear. The purpose of this paper is to propose an estimation method for the optimum bucket size in the event there is a bottlenecked workstation in the work center. The relationship between bottleneck and bucket size is made clear, and due to the relationship, the structure of the equation to set the optimum bucket size in the event there is a bottlenecked workstation in the work center is proposed.

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Asynchronous communication for electronic meeting has inherent difficulties such as what to do when no reply comes back at all, or how to determine whether or not other members are really participating. These problems can sometimes reduce the motivation required for members to participate aggressively. In this paper, we focus on the motivation to participate in electronic meetings, by adding a function that presents the time data of when the document was read (hereafter "Function of Referenced Information") to the electronic meeting system (EMS) in order to show how many times a certain document has been viewed by other members, and thereby give users knowledge of the actions of other members. This function is expected to have two effects; increase members' motivation to participate and concentrate members' attention to the same points. In order to verify the effect, a laboratory experiment was conducted. Two types of EMS were studied : an EMS with the Function of Reference Information and one without the Function of Reference Information. Two types of name presentation methods are investigated : pen name and real name. The members' recognition and change in communication process were measured. The results suggest that the addition of Function of Reference Information does not seem to influence motivation. Also suggested is that, during the first stage of discussion, topics with a higher reading time hit rate are seen as central, thereby preventing the scope of discussion from broadening. Furthermore, members understand what the central topics are for discussion during the middle and end stages, indicating that the function promotes more focused discussion.

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Until now, knowledge engineering has established very effective ways for translating tacit knowledge into explicit knowledge by formulating individual knowledge or skills for intelligent machines, and so on. Knowledge models show agents that assimilate human beings by adding sense and behavior, and further about knowledge transfer among agents. Recently knowledge management has begun to be used widely to carry out organizational or corporate strategies. It focuses on planning and organizing knowledge constructed from both organizational and individual levels. This makes it possible to breakdown strategies as executable concrete tactics because either direct or indirect working departments expect high productivity from every person and thus execute many tasks that require more explicit knowledge to be provided from all organizations. In this paper, we propose a knowledge composition method that plays an important role in structuring or identifying the whole set of related knowledge needed to realize a business objective. First, the "Major Knowledge Composition Method" is used to breakdown the original "objective knowledge" into wide suspecting sorts of "major knowledge" by adding relation, rule and an inference mechanism identified by the supervising team that works on it. Next each set of major knowledge is formulated by a specialist group to be articulated as organizational knowledge by the "Organizational Knowledge Composition Method" through adding relation, rule and an inference mechanism derived from the group's knowledge. Third, the "Individual Knowledge Composition Method" leads organizational knowledge to individual knowledge, in which individual knowledge, both explicit and tacit, is structured based on "Japanese word structure." Finally, the "Objective Knowledge Composition Method" is applied to the results of the structured set of major, organizational and individual knowledge to be recomposed by adding relation, rule and an inference mechanism owned by the supervisor group's knowledge. We applied this method to manage the objectives of an e-business that customers can use easily and conveniently. It made clear that this method can effectively organize objective knowledge from organizational and individual knowledge according to website, process method of receiving and ordering products, collection of payment, and method of handling with problems.

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This paper studies the price-quality strategies of two competing firms where consumers have a homogeneous preference. We use a microeconomic approach to investigate these strategies. Given the consumer demand, a duopolistic setting is described where each of two firms decides both the price and quality levels that maximize their profits. We develope a linear model for price-quality duopolistic competition with a heterogeneous preference presented by Banker et al. and apply it to that with a homogeneous preference. In our model, linearity is assumed for the demand function and cost function for quality improvement. The demand functiton is characterized as a function of product "value", which incorporates price and quality levels. Based on this model, we investigate the optimal price-quality strategies of the firms and the competition resulted from these strategies. It is shown that one-sided competition of price or quality can occur under some demand structures. We furthermore consider a complementary firm with competitive firms and the vertical alliance of two firms. The alliance effect can be evaluated by the difference of profits between the pre- and post-alliance of the two firms. The difference of "value" is also evaluated as an effect for consumers. We derive both of them and observe the alliance effect qualitatively. It is shown that the vertical alliance has a positive effect under strong quality-elastic demand, but it is not necessarily an effective strategy under other environments. Some numerical experiments are conducted in order to illustrate the usefulness of our analytical results.

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A method for designing flexible mixed-product lines is presented. The word "flexible" means product-mix flexibility. A flexible mixed-product line is capable of executing various production plans. Each production plan represents the quantity scheduled to assemble each product type within a time specific period. This design method consists of a new algorithm imitating the fission of living beings and has been created to solve design problems where search trees branch out. The algorithm is called the "fissiparous algorithm" and could be an evolutionary algorithm. Conventional evolutionary algorithms change chromosomes randomly or according to probabilistic rules. But the fissiparous algorithm does not change chromosomes in this manner. This algorithm changes the chromosomes of each individual in the population by a power accelerating the evolution. A chromosome is a string of the order numbers discriminating tasks (elemental works). This design method searches out a solution to the design problem by assigning tasks in the chromosome to each workstation and selecting a kind of "station condition." Station condition is a set of production factors (e.g., worker, robot, equipment or those complex and tools) capable of performing the tasks assigned to each workstation. This design method requires the following data and information. (1) The product types to be assembled on the same line. (2) The various production plans to be executed. (3) The precedence diagram of each product type and the combined precedence diagram. The types of station conditions capable of performing each task and performance times are written in the diagram. A station ability to perform a task determines the task performance time. This design method adopts the goal of minimizing the number of workstations to execute each production plan within a time specific period. The validity of this method was confirmed by solving problems.

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This paper proposes a makespan minimization procedure for job-shop scheduling problems. The primal objective is to find a minimum makespan schedule by generating and evaluating active schedules implicitly and efficiently under the mechanism of branch and bound. This scheduling method allocates operations from time zero toward the end of the schedule gradually, a characteristic favorable when calculating the lower bound on other criteria. In general, however, it is difficult to calculate a good lower bound on the makespan in earlier branching stages, and thus the branching decision must be made based on considerably under-estimated values. Therefore the approach is time-consuming in general. If this weakness is overcome, the approach can be used to optimize another criterion among minimum makespan schedules. The Lagrangean relaxation technique, which is an effective sub-optimization approach, is adopted in order to improve the branching decisions. Our approach first solves the Lagrangean relaxation problem in order to obtain the average start time of operations. This value is used to determine the priority among sub-problems to be solved. Each sub-problem is generated by placing one candidate operation before all other candidates. The subproblem, of which the front-placed operation has the minimum average start time, is solved first even if it has a greater lower bound on the makespan than others. The effectiveness of the proposed approach is investigated by solving 24 benchmark problems. The results indicate that our approach often shows better performance than an ordinary lower-bound-based branching strategy.

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Recently, the concept of cellular manufacturing has been introduced into the part assembly workshop as a new paradigm of improving productivity. In the assembly operations in the cellular manufacturing system, a worker plays a role of a carrier of jobs from a workstation to the next workstation or to the material supply selves to fetch assembly parts and his work is generally performed while walking in many cases. This paper presents a method for estimating walking time by individual step length based on three experiments. The experimental walking models consist of distances of 10 steps, 3 steps and 2 steps. Subjects were instructed to start walking from the standing posture with their legs put together and to stop walking with same posture. Therefore, two movements of one's legs resulted in a length of one step. Walking action is defined as two steps walking in these experiments. The experiments involving 10-step walking revealed characteristics in walking time as follows : At the beginning and end of walking, steps were not constant in length and time, but in the middle of walking, step length and time were constant. The strides of taller examinees were longer and walking took more time than shorter examinees. Individual steps also showed differences in length and time. The length of a step was proved to correlate with an examinee's height. Based on the characteristics mentioned above, it is concluded that walking time can be estimated by an equation with variables indicating the number of steps taken by the examinee and his height. Walking time for 3 steps, though low in constancy of length and time, can be estimated by an equation with variables indicating the examinee's height. Walking time for 2 steps can be estimated by an equation with variables indicating the ratio of the length of the examinees stride to their height.

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This paper considers the job-shop scheduling problem of minimizing the total holding cost of completed and processing products subject to no tardy jobs since meeting due dates is the most important goal of scheduling if the due date of each job has been promised to its customer. A heuristic algorithm based on the shifting bottleneck procedure is proposed for solving the minimum total holding cost problem subject to no tardy jobs. The purpose of this paper is that larger size problems, for example a problem comprising 15 jobs and 15 machines, and more severe due dates problems can be effectively solved. The proposed algorithm decomposes the job shop problem into a number of single-machine problems with ready time and due time constraints. Each decomposed problem is strictly solved by a branch and bound algorithm using new due dates for each operation decided by considering to meet prespecified due dates and minimizing objective functions, simultaneously. We used an elimination method adapted for a single-machine problem at any node to directly select some disjunctions or at least to determine whether or not a potentially optimum solution can be obtained. In this way, the branch and bound tree is trimmed efficiently. Some benchmark problems used by job-shop scheduling to minimize makespan are solved by the proposed algorithm and the results are reported.

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One of the characteristics of Japanese production systems is, as seen in improvement activities on the shop floor, that the some degree of autonomy is built into the production process. Recently, cell production systems featuring decentralized structures have been introduced in electric, electronics, and other industries. We characterize these systems as having some degree of autonomy and decentralization, thus realizing greater adaptability, and in turn, raising productivity. Here, we construct a conceptual model and propose a design framework for cell production systems, including autonomy and decentralization as design parameters, and considering adaptability and productivity as the objectives.

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