• Journal of the Korean Operations Research and Management Science Society
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• v.20 no.1
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• pp.179-193
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• 1995

A multi-objective, single-stage scheduling problem with stochastic processing times is considered where the objective is to simultaneously minimize the expected value and the variance of total flowtime, and the mean probability of tardiness. In cases where processing times follow normal distributions, a method using pairwise interchange of two jobs(PITJ) is proposed to generate a set of the approximate efficient schedules. The efficient schedules are not dominated by the criterion vectors of any other permutation schdules in the feasible region. Numerical experiments performed to ascertain the effectiveness of PITJ algorithm are also reported in the results.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.147-157
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• 2006

In this paper we consider alternate m machine scheduling problem in which each job having at most two eligible machines should be assigned with the objective of makespan minimization. For this problem, we propose a $O(m2^m)$ time rounding algorithm with performance ratio at most 1.5. For a little general problem where each job can be processed at most three machines, we prove that there cannot exist a polynomial time algorithm with performance ratio less than 1.5.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.201-204
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• 2006

In this paper, we propose efficient scheduling strategy for Multi-user MIMO systems that find advantageous trade off solution between multiuser diversity and spatial diversity, spatial multiplexing technique. Specifically, we suggest P-SFS(Pseudo-SNR Fair scheduling) algorithm that consider throughput and fairness problem. also we propose channel aware Antenna deployment that decide how to use assigned multiple antennas by the information of each user's channel condition.

• Journal of the military operations research society of Korea
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• v.9 no.1
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• pp.51-61
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• 1983

Lagrangian relaxation is used to the problem of scheduling jobs on unrelated parallel processors with the objective of minimizing makespan. The implicit condition for optimality is drawn out explicitly in order to apply the subgradient algorithm. To obtain the optimal solution, branch-and-bound-search method is devised. In the search, the special structure of the problem is exploited effectively, Some computational experiences with the algorithm are presented, and comparisons are made with the Land and Doig method.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.145-150
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• 2003

The parallel machine scheduling problem or assigning n jobs on m identical machines with the objective of minimizing makespan is considered. In this note, we apply the PTAS (Polynomial Time Approximation Scheme) or Hochbaum and Shmoys to our problem and show that it is still a PTAS for our problem.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.46-49
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• 1996

This paper presents a multi-pass heuristic for job shop scheduling with due dates. The proposed heuristic iteratively improves solutions based on operation due dates. To find a good solution efficiently, a method for searching the neighborhood of current schedule is developed. The heuristic is compared with two existing heuristics as well as several dispatching rules in terms of solution quality and computation time. The experimental results show that the proposed approach is promising.

• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.1
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• pp.69-77
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• 1979

A single machine stochastic scheduling problem is considered. Associated with each job is its random processing time and random deferral cost. The criterion is to order the jobs so as to minimize the sum of the deferral costs. The expected sum of the deferral costs is theroretically derived under the stochastic situation for each of several scheduling decision rules which are well known for the deterministic environment. It is also shown that certain stochastic problems can be reduced to equivalent deterministic problems. Two examples are illustrated to show the expected total deferral costs.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.3
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• pp.159-170
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• 1992

The size of time constaints is the critical bottleneck of the Crew Scheduling Problem (CSP). This paper deals with a method to extract the minimum required time constraints by k-shortest path algorithm. These time constraints are added as the "insurance constraints" to avoid the unnecessary tree search, which are very time-consuming procedures, for the integer solutions. The computational results show that the problem size in LP formulation could be reduced by our method.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.3
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• pp.1-12
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• 1992

Parallel Genetic Algorithms (GAs) are developed to solve a single machine n-job scheduling problem which is to minimize the sum of absolute deviations of completion times from a common due date. (0, 1) binary scheme is employed to represent the n-job schedule. Two selection methods, best individual selection and simple selection are examined. The effect of crossover operator, due date adjustment mutation and due date adjustment reordering are discussed. The performance of the parallel genetic algorithm is illustrated with some example problems.

• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.2
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• pp.131-145
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• 1993

This paper deals with scheduling problem of the chemical process system where aircraft parts go through a given sequence of tanks filled with chemical solutions. The system has two hoists which move carriers holding the parts between tanks. A mixed integer programming model is developed from which a maximum throughput schedule can be found for the hoist movements. To show the validity of the model, a real world problem is solved and the results are compared with those with an existing approach.