• Journal of Korean Institute of Industrial Engineers
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• v.25 no.4
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• pp.411-420
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• 1999

A mixed model production line is a production line where a variety of product models are produced. In U-shaped production lines (called U-lines) used in just-in-time production system, the strategy of mixing product models is often used to provide various types of products to customers in time. Line balancing and model sequencing problems are important for an efficient use of mixed model U-lines. Although the two problems are tightly interrelated with each other, prior researches have considered them separately or sequentially. This paper presents a new method using a coevolutionary algorithm that can solve the two problems at the same time. To promote diversity and search efficiency, in this paper the evolutionary system is based on the localized interactions within and between populations. Methods of selecting environmental individuals and evaluating fitness are developed. Efficient genetic representations and operator schemes are also provided. When designing the schemes, we take into account the features specific to the problems. The experimental results demonstrate that the proposed algorithm is superior to existing approaches.

• Journal of the Korea Safety Management & Science
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• v.6 no.2
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• pp.115-125
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• 2004

This paper presents a new method that can efficiently solve the integrated problem of line balancing and model sequencing in mixed-model U-lines (MMULs). Balancing and sequencing problems are important for an efficient use of MMULs and are tightly related with each other. However, in almost all the existing researches on mixed-model production lines, the two problems have been considered separately. A genetic algorithm for balancing and sequencing in mixed-model U line is proposed. A presentation method and genetic operators are proposed. Extensive experiments are carried out to analyze the performance of the proposed algorithm. The computational results show that the proposed algorithm is promising in solution quality.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3863-3869
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• 2009

In recent years, globalization of markets and increased consumer sophistication in automotive industry have led to an increase in the variety of products and a consequent increase in the number of variants of any given product line that a manufacturer must supply. Also, the modularity trend of automotive production systems greatly affects on the production systems of automotive parts suppliers. These typically requires the implementation of cost efficient, flexible production systems, so called mixed-model assembly lines. We studied the problems of mixed-model assembly and assembly error-preventing techniques, and developed the error-preventing monitoring system using RFID in the mixed-model automotive parts assembly line. Especially, this study aimed to solve the problems and supplement the existing systems for preventing assembly errors, by developing a monitoring system using RFID to minimize the issues currently occurring in the field of automotive parts assembly, such as losses from incorrect installation and omission.

• Proceedings of the Safety Management and Science Conference
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• 2002.05a
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• pp.91-97
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• 2002

In this thesis presents line balancing problems of two-sided and mixed model assembly line widely used in practical fields using genetic algorithm for reducing throughput time, cost of tools and fixtures and improving flexibility of assembly lines. Two-sided and mixed model assembly line is a special type of production line where variety of product similar in product characteristics are assembled in both sides. This thesis proposes the genetic algorithm adequate to each step in tow-sided and mixed model assembly line with suitable presentation, individual, evaluation function, selection and genetic parameter. To confirm proposed genetic algorithm, we apply to increase the number of tasks in case study. And for evaluation the performance of proposed genetic algorithm, we compare to existing algorithm of one-sided and mixed model assembly line. The results show that the algorithm is outstanding in the problems with a larger number of stations or larger number of tasks.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.90-97
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• 2014

Nash Cournot Equilibrium (NCE) has been widely used in a competitive electricity market to analyze generation firms' strategic production quantities. Congestion on a transmission network may lead to a mixed strategy NCE. Mixed strategy is complicated to understand, difficult to compute, and hard to implement in practical market. However, Stackelberg model based equilibrium does not have any mixed strategy, even under congestion in a transmission line. A guide to understanding mixed strategy equilibrium is given by analyzing a cycling phenomenon in the players' best choices. This paper connects the concept of leader-follower in Stackelberg model with relations between generation firms on both sides of the congested line. From the viewpoint of social welfare, the surplus analysis is presented for comparison between the NCE and the Stackelberg equilibrium (SE).

• Journal of the Korea Safety Management & Science
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• v.4 no.2
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• pp.83-101
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• 2002

In this thesis presents line balancing problems of two-sided and mixed model assembly line widely used in practical fields using genetic algorithm for reducing throughput time, cost of tools and fixtures and improving flexibility of assembly lines. Two-sided and mixed model assembly line is a special type of production line where variety of product similar in product characteristics are assembled in both sides. This thesis proposes the genetic algorithm adequate to each step in tow-sided and mixed model assembly line with suitable presentation, individual, evaluation function, selection and genetic parameter. To confirm proposed genetic algorithm, we apply to increase the number of tasks in case study. And for evaluation the performance of proposed genetic algorithm, we compare to existing algorithm of one-sided and mixed model assembly line. The results show that the algorithm is outstanding in the problems with a larger number of stations or larger number of tasks.

• IE interfaces
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• v.10 no.3
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• pp.209-216
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• 1997

This mixed push and pull production system defines that all stages are not ordered by either of the production systems. Some stages are ordered by a push-type production system and the other stages are ordered by a pull-type production system. A decision support system is built by using a combination of optimization program and the "tunable" SIMAN discrete-event simulation for the implementation of an optimally mixed production system. Finding this optimal system requires 6 CPU hours for the case study on a Pentium. Both the simulation and optimization model are validated with a case study of Phoenix company that manufactures transmitters. This paper uses survey from experts in this company for evaluation and validation of this system.

• Journal of the Korean Operations Research and Management Science Society
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• v.26 no.4
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• pp.109-124
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• 2001

This paper presents a new method that can efficiently solve the integrated problem of line balancing and model sequencing in mixed model assembly lines (MMALs). Line balancing and model sequencing are important for an efficient use of MMALs. The two problems of balancing and sequencing MMALs are tightly related with each other. However, In almost all the existing researches on mixed-model production lines, the two problems have been considered separately. In this research, an endosymbiotic evolutionary a1gorithm, which is a kind of coevolutionary a1gorithm, is adopted as a methodology in order to solve the two problems simultaneously. This paper shows how to apply an endosymbiotic evolutionary a1gorithm to solving the integrated problem. Some evolutionary schemes are used In the a1gorithm to promote population diversity and search efficiency. The proposed a1gorithm is compared with the existing evolutionary algorithms in terms of solution quality and convergence speed. The experimental results confirm the effectiveness of our approach.

• Journal of the Korea Society for Simulation
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• v.22 no.2
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• pp.93-100
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• 2013

Mixed model production system means that various products are manufactured alternately in a line, and it has become a popular system in the era of multi-product small-quantity production. However, in the mixed model production system using flow line, the unbalance among stations is not inevitable because the workloads of stations cannot be the same. Thus, flow line system has been replaced to cellular manufacturing system for reducing the loss of waiting due to the unbalance of stations. In this paper, we introduce the simulation case study of an automated welding line which produces the parts of excavator. The factory has considered replacing the mixed model flow line to the cellular manufacturing system based on FMC concept. The increase of production quantity is estimated about 26.7%, and the lead time is reduced more than 55%. Furthermore sensitivity analyses are conducted considering the changes of product-mix.

• Journal of the Korea Society for Simulation
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• v.11 no.4
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• pp.69-80
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• 2002

This study deals with the productivity improvement on a flow production system with the consideration of line-balancing. In a flow production system, similar product models are produced on a same assembly line, the predefined process order and the limitation of total worker number. The system can be increased the work-in -process(WIP) inventory and the worker's idle time. In this study, the worker assignment model is developed to assign evenly workload of process to each product model in such a manner that each process has the different number of worker. This worker assignment model is the mathematical model that determines worker number in each process such that the idle time of processes is reduced and the utilization of worker is improved. We use a simulation technique to simulate the production line proposed by the mathematical model and apply real production line. With the result of simulation, this study analyzes the propriety of production line and proposes the alternatives of new production line