• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2006.05a
• /
• pp.1124-1132
• /
• 2006

This paper considers a flow shop scheduling problem where a different WIP (work-in-process) state has different weight on the duration time. The objective is to minimize the sum of the weighted WIP. For the two machine flow shop case, the recognition version is unary NP-Complete. The three simple and intuitive heuristics H0, H1, and H2 are presented for the problem. For each heuristic, we find an upper bound on relative error which is tight in limit. For heuristic H2, we show that H2 dominates the other two heuristics.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2006.05a
• /
• pp.1133-1138
• /
• 2006

This paper considers a hybrid flow shop scheduling problem for the objective of minimizing the number of tardy jobs. The hybrid flow shop consists of two stages in series, each of which has multiple identical parallel machines, and the problem is to determine the allocation and sequence of jobs at each stage. A branch and bound algorithm that gives the optimal solutions is suggested that incorporates the methods to obtain the lower and upper bounds. Dominance properties are also derived to reduce the search space. To show the performance of the algorithm, computational experiments are done on randomly generated problems, and the results are reported.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.8 no.1
• /
• pp.41-46
• /
• 2012

In this paper, An efficient circuit design algorithm considering constraint is proposed. The proposed algorithm sets up in time constraint and area constraint, power consumption constraint for a circuit implementation. First, scheduling process for time constraint. Select the FU(Function Unit) which is satisfied with time constraint among the high level synthesis results. Analyze area and power consumption of selected FUs. Constraint set for area and power constraint. Device selection to see to setting condition. Optimization circuit implementation in selected device. The proposed algorithm compared with [7] and [8] algorithm. Therefore the proposed algorithm is proved an efficient algorithm for optimization circuit implementation.

• Journal of Korean Institute of Industrial Engineers
• /
• v.40 no.3
• /
• pp.305-312
• /
• 2014

This research deals with a problem that minimizes makespan in a non-identical parallel machine system with sequence and machine dependent setup times and machine dependent processing times. We first present a new mixed integer programming formulation for the problem, and using this formulation, one can easily find optimal solutions for small problems. However, since the problem is NP-hard and the size of a real problem is large, we propose four heuristic algorithms including genetic algorithm based heuristics to solve the practical big-size problems in a reasonable computational time. To assess the performance of the algorithms, we conduct a computational experiment, from which we found the heuristic algorithms show different performances as the problem characteristics are changed and the simple heuristics show better performances than genetic algorithm based heuristics for the case when the numbers of jobs and/or machines are large.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.30 no.1
• /
• pp.27-41
• /
• 2005

This paper considers identical parallel machine scheduling problem. Each job has a processing time. due date. weight and family type. If a different type of job is followed by prior job. a family setup is incurred. A two phased heuristic is presented for minimizing the sum of weighted tardiness. In the first phase. using roiling horizon technique. group each job into same family and schedule each family. In the second phase. assign each job to machines using schedule obtained in the first phase. Extensive computational experiments and comparisons among other algorithms are carried out to show the efficiency of the proposed algorithm.

• Korean Management Science Review
• /
• v.16 no.2
• /
• pp.125-135
• /
• 1999

This paper presents a framework for the hierarchical PPC(Production Planning and Control) in make-to-order environment with job shop. The characteristics of the environment are described as : 1) project with non-repetitive and individual production, 2) short delivery date, 3) process layout with large scales manufacturing. 4) job shops. The PPC in a make-to-order typically are organized along hierarchical fashions. A model is proposed for the hierarchical job shop scheduling based on new concepts of production system, work and worker organization. Then, a new integrated hierarchical framework is also developed for the PPC based on concepts of the proposed job shops scheduling model. Finally, the proposed framework has been implemented in the Electric Motor Manufacturing and the results showed good performance.

• Journal of Korean Society for Quality Management
• /
• v.17 no.1
• /
• pp.116-124
• /
• 1989

A multi-period production-inventory scheduling model, which extends the customary dynamic lot sizing model to the one for deteriorating items, is developed. The amount of deterioration during a period is assumed to be proportional to the on-hand inventory at the end of the period. It is futher assumed that the deterioration rates vary from period to period. In addtion, an expediting cost due to the delay of outstanding order is included and it is allowed to offset the order release date in advance, instead, in order to avoid incurring the cost. Finally, a quasi-WW algorithm corresponding to the Wagar-Whitin algorithm is proposed to obtain the optimal production-inventory schedules.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.22 no.51
• /
• pp.231-240
• /
• 1999

A major concern in Concurrent Engineering is the control and management of workload in a period of process. As a general rule, leveling the peak of workload in certain period is difficult because concurrent processing is comprised of various processes, including overlapping, paralleling looping and so on. Therefore, the workload management with resource constraints is so beneficial that effective methods to analyze design process are momentous. This study presents the Timed Petri Nets approach of precedence logic networks, and provides an alternative for users to analyze constraint processes to resolve conflicts of resources. Another approach to Continuous Time Markov Chain using Stochastic Petri Nets is also proposed. These approaches are expected to facilitate resolving resource constrained scheduling problems more systematically in Concurrent Engineering environment.

• Proceedings of the Safety Management and Science Conference
• /
• 2003.11a
• /
• pp.93-96
• /
• 2003

In this regard, the newly focused logistics information system makes reducing the expenses of whole logistic available by cutting down the expenses of materials, transportation and stock and also, it allows the company to cut down the procurement expense through the reduced lead-time and rationalize producing plans by eliminating the uncertain orders and fluctuation in procurement. It further more optimizes the efficiency of over all productions by meeting the dead line for delivery to the customers. In the recent environment of globalization where fierce competitions exist between manufacturers, logistics plays important role in the strategies of companies, and managements of companies try their best efforts in establishing the strategy to accomplish the innovative relationship between supply chain channels. Therefore, in this study, we try to suggest the model of consolidated logistics system that is integrated logistics information system with suggesting the better way of logistics and comparative analysis with logistics system to resolve the difficulties numbers of companies face after realizing what logistics information system is in Korea.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2002.05a
• /
• pp.686-692
• /
• 2002

Disassembly scheduling is the problem of determining the ordering and disassembly schedules of used products while satisfying the demand of their parts of components over a certain planning horizon. The objective is to minimize the sum of purchase, setup, disassembly operation and inventory holding costs. This paper considers products with assembly structure, i.e. products without parts commonality, and suggests a heuristic in which an initial solution is obtained in the form of the minimal latest disassembly schedule, and then improved considering trade-offs among different cost factors. To show the performance of the heuristic suggested in this paper, computational experiments were done on the modified existing examples and the results show that the heuristic can give optimal of very near optimal solutions within very short computation times.