• Journal of the Korean Operations Research and Management Science Society
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• v.13 no.1
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• pp.13-13
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• 1988

This paper considers the sequencing problem in mixed model assembly lines with hybrid workstation types and sequence-dependent setup times. Computation time is often a critical factor in choosing a method of determining the sequence. We develop a mathematical formulation of the problem to minimize the overall length of a line, and present a tabu search technique which can provide a near optimal solution in real time. The proposed technique is compared with a genetic algorithm and a branch-and-bound method. Experimental results are reported to demonstrate the efficiency of the technique.

• Proceedings of the Safety Management and Science Conference
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• 2001.05a
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• pp.195-198
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• 2001

This paper addresses the problem of placing tools in a tool magazine with random-select capability on a flexible machine. The tool placement problem could be a significant portion of the total processing time. It is assumed that the total number of tools required to process a set of parts exceeds the available magazine capacity, and so tool switches may occur between two adjacent parts in a given part sequence. Two heuristics are presented so as to minimize the total travel distance of the tool magazine before the completion of all parts.

• Journal of information and communication convergence engineering
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• v.14 no.2
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• pp.71-77
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• 2016

The combination of dispersion management (DM) and midway optical phase conjugation (OPC) is one of the promising techniques for compensating for optical signal distortion due to group velocity dispersion and nonlinear fiber effects. However, in this combination technique, midway OPC restricts the flexible optical link configuration. Therefore, the possibility of implementing the flexible optical link configuration with non-midway OPC applied to complete inline DM links is investigated in this study. It is confirmed that although the compensation using non-midway OPC for the distorted WDM channels is less effective than that using midway OPC, when non-midway OPC is placed at positions closer to the transmitters, the deployment of precompensation (i.e., the sequence of DCF + SMF)-OPC-postcompensation (i.e., the sequence of SMF + DCF) is more advantageous for the compensation. On the other hand, inverse deployment with respect to OPC (i.e., postcompensation-OPC-precompensation) is more advantageous when non-midway OPC is placed at positions closer to the receivers.

• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.2
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• pp.15-27
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• 1998

In the parallel processing systems, a compiler partitions a loaded program into tasks, allocates the tasks on multiple processors and schedules the tasks on each allocated processor. In this paper we suggest a Genetic Algorithm(GA) based scheduling method to find an optimal allocation and sequence of tasks on each Processor. The suggested method uses a chromosome which consists of task sequence and binary string that represent the number and order of tasks on each processor respectively. Two correction algorithms are used to maintain precedency constraints of the tasks in the chromosome. This scheduling method determines the optimal number of processors within limited numbers, and then finds the optimal schedule for each processor. A result from computational experiment of the suggested method is given.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.280-287
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• 1994

본 논문에서는 광양제철소의 연속소둔공정의 작업단위편성 문제를 소개하고, 그 해결방안을 제시한다. 다루고자 하는 문제는 편성할 스케줄 내에서 전후 대상재간의 다양한 형태의 편차를 최소화하며 sequence의 길이를 최대화하 는 목적함수를 가지며, 동시에 공정의 특성상 발생하는 전후 대상재간의 제 약조건들을 만족시키는 문제이다. 이러한 문제를 해결하기 위하여 부분 최적 해를 구해 주는 순차적인 두가지 발견적(heuristic)기법을 제시한다. 첫째, 일 정의 길이를 최대화하며 전후 대상재간의 제약조건을 만족시키기 위한 "backtracking with look ahead" 기법이다. 특히 이 "backtracking with look ahead" 기법은 이미 개발된 "constraint satisfaction problem"을 기반으로 한 일정계획언어와 이에 연동된 코드생성기를 사용하여 구현되었다. 둘째, sequence내 전후 대상재간의 다양한 형태의 편차를 최소화하며 앞에서 만족 시킨 제약조건들을 계속 유지시키기 위한 평활화(smoothing) 기법이다. 마지 막으로 두가지 발견적 기법을 사용하여 본 연속소둔공정의 작업단위편성 문 제를 해결하는 과정을 보여준다. 이와 같은 발견적 기법을 이용하여 기존의 기법들로는 해결하기 힘든 복잡한 형태의 일정 계획 문제를 해결할 수 있었 다. 복잡한 형태의 일정 계획 문제를 해결할 수 있었 다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.533-544
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• 1992

한 제품의 구성 부품 수가 증가함에 따라 조립/분해 순서의 방법수는 기하급수적으로 증가한다. 또한 이 순서의 선택에 의하여 조립/분해의 효율성이 결정된다. 본 논문에서는 조립제품의 조립순서(Assembly Sequence)와 특정부품의 효율적 교체(Part Replacement)를 위한 분해순서(Disassembly sequence)에 관한 새로운 Algorithm들을 다음 3가지 경우를 통하여 소개한다 : 1) Full Assembly/Disassembly, 2) Part Replacement by Individual Disassembly, 그리고 3) Part Replacement by Group Disassembly. 이들 Algorithm들은 'Freedom and Interference Space'라는 새로운 개념으로부터 유도되며, Group Disassembly는 Carpenter's Approach를 통하여 실현된다. 이 논문에서 소개되는 Algorithm들은 조립/분해순서와 함께 조립/분해 방향도 제시하는데 비교적 복잡한 예를 통하여 이들을 실현함으로써 실제 제품 Design에의 활용 가능성을 보여준다.

• Korean Management Science Review
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• v.21 no.3
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• pp.115-127
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• 2004

In this paper, we describe an intelligent monitoring and control system for pick-up/delivery service. This system applies geographical information system(GIS), global positioning system(GPS) and wireless communication technologies for managing pick-up/delivery operations more effectively. It consists of three subsystems, pick-up/delivery sequence planning system, pick-up/delivery monitoring system, and PDA execution system. Pick-up/delivery sequence planning system generates routes and schedules for pick-up/delivery using GIS and optimization techniques. Pick-up/delivery monitoring system monitors current positions of vehicles and actual pick-up/delivery results as compared with planned routes and visit times, while PDA execution system transmits information for vehicles positions and actual pick-up/delivery results using GPS and wireless communication technologies. The intelligent monitoring and control system is currently being used for the pick-up parcel service in a local post office of Korea Post.

• Journal of the Korean Operations Research and Management Science Society
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• v.26 no.2
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• pp.69-83
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• 2001

The problem of minimizing total tardiness on a batch processing machine with incompatible job families when there are sequence independent setup times between families is studied where all jobs of the same family have identical processing times and jobs of different families cannot be processed together. A batch processing machine can process a number of jobs, within a maximal batch size, simultaneously as a batch. The processing time required of each batch is equal to the one of jobs. A dynamic programming algorithm which gives the optimal solution, and several heuristics are presented. Performance of simple dispatching rules based on due dates are compared, and the best of them is used as an initial solution for the decomposition algorithm, which is shown to give good schedules in relatively short computational time.

• Management Science and Financial Engineering
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• v.11 no.2
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• pp.45-60
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• 2005

This paper investigates the application of the computer method COMSOAL (Computer Method of Sequencing Operations for Assembly Lines) to the process routing (PR) problem with multiple objectives. In any computer aided process planning (CAPP) system, one of the most critical activities for manufacturing a part could be to generate the sequence that optimizes production time, production cost, machine utilization or with multiple these criteria. The COMSOAL has been adopted to find the optimum sequence of operations that optimizes two major conflicting criteria : production cost and production quality. The COMSOAL is here slightly modified to simultaneously generate and evaluate a set of possible solutions (called as population) instead of processing a solution stepwise in each iteration. The significant features of the COMSOAL include : no parameters settings needed, and a guarantee of feasible solutions. Experimental results show that COMSOAL is a simple but powerful method to quickly generate multiple feasible solutions which are as good as the ones obtained from several other well-known process routing algorithms.

• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.1
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• pp.139-157
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• 1993

This paper presents possibilistic job scheduling based on the membership function as an alternative to probabilistic job scheduling and illustrates a methodology for solving job sequencing problem which the opinions of experts greatly disagree in each processing time. Triangular fuzzy numbers are used to represent the processing times of experts. Here, the comparison method is based on the dominance property. The criteria for dominance are presented. By the dominance criteria, for each job, a mojor TFN and a minor TFN are selected and apessimistic sequence with mojor TFNs and an optimistic sequence with minor TFNs are computed. The three-machine flow shop problem is considered as an example to illustrate the approach.