• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1733-1739
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• 2006

This paper is concerned with multi-objective vehicle routing problem(VRP), in which objective of this problem is to minimize the total operating time of vehicles and the total tardiness of customers. A mixed integer programming formulation and a heuristic for practical use are suggested. The heuristic is based on the route-perturbation and route-improvement method(RPRI). Performances are compared with other heuristic appeared in the previous literature using the modified bench-mark data set. It is shown that the suggested heuristic give good solution within a short computation time by computational experiment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.31
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• pp.115-123
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• 1994

Group scheduling, which is a kind of operations scheduling based on the GT concept is analyzed in a multi-stage manufacturing system. The purpose of this research is to develop and evaluate a heuristic algorithm for determining gro up sequence and job sequence within each group to minimize a complex cost function, i.e. the sum of the total pe-nalty cost for tardiness and the total holding cost for flow time, in a multi-stage manufacturing system with group setup time dependent upon group sequence. A heuristic algorithm for group sc heduling is developed, and a numerical example is illustrated. For the evaluation of the pro-posed heuristic algorithm, the heuristic solution of each of 63 problems is compared with that of random scheduling. The result shows that the proposed heuristic algorithm provides better solution in light of the proposed cost function.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.612-615
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• 2002

The objective of this study is to develop an integrated process planning system which can flexibly cope with the status changes in a shop floor by utilizing the concept of Non-Linear and Closed-Loop Process Planning(NCPP). In this paper, Genetic Algorithm(GA) is employed in order to quickly generate feasible setup sequences for minimizing the makespan and tardiness under an NCPP. The genetic algorithm developed in this study for getting the machine load utilizes differentiated mutation rate and method in order to increase the chance to avoid a local optimum and to reach a global optimum. Also, it adopts a double gene structure for the sake of convenient modeling of the shop floor. The last step in this system is a simulation process which selects a proper process plan among alternative process plans.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.704-708
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• 2002

Production scheduling has been one of the most critical issues in a manufacturing environment Job-shop scheduling problems(JSP) are well know from the standpoint of production planning and operations control in this research scheduling against due date is a measure of performance and the objective is minimizing total weighted tardiness This paper presents an idea of decomposition of the problem and shows robustmess of the schedule under various disturbances along with exact and approximation methods. The proposed method can indeed handle shop disturbances more effectively when compared with traditional and dynamic scheduling methods.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.2
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• pp.47-57
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• 2000

In this paper we consider an n-job non-preemptive and identical parallel machine scheduling problem of minimizing the sum of earliness and tardiness with different release times and due dates. In the real world this problem is more realistic than the problems that release times equal to zero or due dates are common. The problem is proved to be NP-complete. Thus a heuristic is developed to solve this problem To illustrate its suitability a proposed heuristic is compared with a genetic algorithm for a large number of randomly generated test problems. Computational results show the effectiveness and efficiency of proposed heuristic. In summary the proposed heuristic provides good solutions than genetic algorithm when the problem size is large.

• Proceedings of the Korea Society for Simulation Conference
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• 1993.10a
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• pp.16-16
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• 1993

The efficient use of capital intensive FMS requires determination of effective dispatching priority with which the parts of the selected part types are to be inputed into the system. This paper presents a simulation-optimization approach to find an appropriate dispatching priority. The study is based on a detailed simulator for a module-type commercial FMS, Specifically, after presenting the basic configuration and fundamental control logic of the system together with its main characteristics as a special type of a job shop, an algorithm is presented which combines simulated annealing and simulation to explore a dispatching priority of operations that minimizes the total tardiness, Computational performance of the algorithm shows that good solutions can be obtained within a reasonable amount of computations. The paper also compares the performance of the "optimal" or near optimal dispatching priority generated by the proposed algorithm with those generated by standard dispatching rules such as SPT, EDD and SLACK.

• Proceedings of the Korea Association of Information Systems Conference
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• 2004.11a
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• pp.409-416
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• 2004

동적 공급사슬망은 복잡하고 다양한 이해관계를 가진 기업들로 구성되어 있다. 다수의 구매자로부터 주문 의뢰가 동시다발적으로 발생하므로 하위 구성원들은 경쟁적 관계에 놓이게 된다. 그러므로 최적의 공급사슬구성을 위해서는 수평적 경쟁 관계를 고려하여 구성주체들간의 협력관계를 통해 이를 해결하여야 한다. 지금까지의 스케줄링 문제에서는 상위의 구성원이 하위 구성원들을 일방적으로 선택하는 의사결정이 이루어졌으나 본 문제에서는 구성원간의 협력관계에서 에이전트를 통한 다자간 협상을 통해 공급사슬 전체의 최적화를 구성하는 방법론을 제시한다. 본 협상방법론은 단일기계에서 상이한 납기일, 조기생산(earliness), 지연생산(tardiness)을 동시에 고려하였으며 전체 공급사슬의 평균절대편차(Mean Absolute Deviation)의 최소화를 목적으로 하고 있다. 본 협상방법론의 효과성을 증명하기 위해 분지한계법(Branch & Bound)과 비교하고, 알고리즘 구현을 통해 구매자 협상방법론의 최적화 여부를 실험을 통해 증명하였다.

• IE interfaces
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• v.12 no.1
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• pp.121-131
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• 1999

In this article, a simulation model of a microwave oven assembly line is developed to identify system parameters to improve the system performances such as work-in-process inventories, production lead time, mean earliness, mean tardiness and in-time completion rate. System parameters investigated include dispatching rules, lot sizing, setup time reduction, demand increase, productivity improvement, production scheduling, hardware characteristics, etc. The model has been developed using SIMAN simulation language which has been demonstrated to be a powerful tool to simulate complex manufacturing systems. We have suggested the results obtained to improve the system performances of an existing production line.

• Industrial Engineering and Management Systems
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• v.14 no.4
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• pp.401-412
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• 2015

In this paper, we present a modeling approach to production planning for an actual production line and a heuristic method. We also illustrate the successful implementation of the proposed method on the production line. A heuristic algorithm called the push-back algorithm was designed for a single machine earliness/tardiness production planning with distinct due date. It was developed by combining a minimum slack time rule and shortest processing time rule with a push-back procedure. The results of a numerical experiment on the heuristic's performance are presented in comparison with the results of IBM ILOG CPLEX. The proposed algorithm was applied to an actual case of production planning at Woongjin Chemical, a leading manufacturer of filter products in South Korea. The seven-month execution of our algorithm led to a 24.5% decrease in the company's inventory level, thus demonstrating its practicality and effectiveness.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.52
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• pp.191-201
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• 1999

There have been a huge volume of researches concerning dispatching rules in job shop environments. Strangely, studies all but one pay no attention to multiple identical jobs due to the existence of production orders each of which calls for a fixed quantity, called an order size, of a specific part. Jobs arrive in the form of production orders in most, if not all, job shop type flexible manufacturing systems. This paper presents simple processing-time-based dispatching rules, and shows experimentally based on simulation that the rules with order-size considerations perform consistently well for tardiness and utilization measures. Several alternative strategies for rule specifications are examined.