• Journal of the Korean Institute of Navigation
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• v.22 no.4
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• pp.15-19
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• 1998

This paper concerns a bulk or semibulk cargo ship scheduling problem with a single loading port. This type of ship scheduling problem is frequently needed in real world for carrying minerals or agricultural produce from a major single production zone to many destinations scattered over a large area of the world. The first optimization model for this problem was introduced by Ronen (1986) as a nonlinear mixed integer program. The model developed in this paper is an improvement of his model in the sense that nonlinearities and numerous unnecessary integer variables have been eliminated. By this improvement we could expect real world instances of moderate sizes to be solved optimal solutions by commercial integer programming software. Similarity between the ship scheduling model and the capacitated facility location model is also discussed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.132-133
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• 2015

Efficient scheduling and resource management are the key factor to reduce construction project budget (e.g., labor cost, equipment cost, material cost, etc.). Resource-based line of balance (LOB) technique has been used to complement the limitations of time-driven scheduling techniques (e.g., critical-path method). Optimizing construction alternatives contributes cost savings while honoring the project deadline. However, existing LOB scheduling is lack of identifying optimal resource combination. This study presents a method which identifies the optimal construction alternatives, hence achieving resource minimization in a repetitive construction by using genetic algorithm (GA). The method provides efficient planning tool that enhances the usability of the system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.11
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• pp.1374-1381
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• 1999

This paper describes development of a package for generator maintenance scheduling program with user-friendly interactive mode. Generator maintenance scheduling is to select desirable maintenance periods of generators in the given interval satisfying reliability or economic criteria. Window-based system for user-friendly mode and Oracle-based database system for efficient data management are established in our package. Reserve rate levelization and LOLP minimization are performed in calculation mode, which is composed of DLL programs. Many graphs and charts are illustrated for the user-analysis. Operation is carried out by day-based unit, not by week. The case study has been conducted with the data of practical KEPCO power system in 1999 and successfully demonstrated its effectiveness.

• Journal of Korean Institute of Industrial Engineers
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• v.35 no.4
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• pp.218-225
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• 2009

This paper considers a parallel-machine scheduling problem with job release times and sequence-dependent setup times. The objective of this problem is to determine the allocation policy of jobs and the scheduling policy of machines so as to minimize the weighted sum of setup times, delay times, and tardy times. A mathematical model for optimal solution is derived and a meta heuristic algorithm based on the improved ant colony system is proposed in this paper. The performance of the meta heuristic algorithm is evaluated through compare with optimal solutions using randomly generated several examples.

• Industrial Engineering and Management Systems
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• v.11 no.1
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• pp.94-102
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• 2012

In this paper, an interactive planning and scheduling framework are proposed for optimising operations from pits to crushers in ore mining industry. Series of theoretical and practical operations research techniques are investigated to improve the overall efficiency of mining systems due to the facts that mining managers need to tackle optimisation problems within different horizons and with different levels of detail. Under this framework, mine design planning, mine production sequencing and mine transportation scheduling models are integrated and interacted within a whole optimisation system. The proposed integrated framework could be used by mining industry for reducing equipment costs, improving the production efficiency and maximising the net present value.

• Korean Management Science Review
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• v.29 no.1
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• pp.131-141
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• 2012

The automated material handling systems today are playing ever more important roles in semiconductor/LCD fabrication facilities. Recently they became more flexible, intelligent, and speedy than in the past. The facilities have been fully automated because the size and weight of the unit loads used in the facilities were being increased beyond the limits that a human operator can handle. This research develops an efficient procedure to streamline the delivery of unit loads by the automated material handling system (AMHS). For this task, the research employs the event scheduling theory that has been successfully used in the both academia and industry. The developed procedure was applied to an actual LCD fabrication facility and improved the performance of an existing material handling system.

• Journal of the Korean Operations Research and Management Science Society
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• v.15 no.1
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• pp.99-115
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• 1990

This paper is concerned with the unit commitment problem in an electric power system with both thermal and pumped-storage hydroelectric units. This is a mixed integer programming problem and the Lagrangean relaxation method is used. We show that the relaxed problem decomposes into two kinds of subproblems : a shortest-path problem for each thermal unit and a minimum cost flow problem for each pumped-storage hydroelectric unit. A method of obtaining an incumbenet solution from the solution of a relaxed problem is presented. The Lagrangean multipliers are updated using both subgradient and incremental cost. The algorithm is applied to a real Korean power generation system and its computational results are reported and compaired with other works.

• Industrial Engineering and Management Systems
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• v.3 no.1
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• pp.12-21
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• 2004

This paper investigates the design of a priority rule in a multi-product disassembly environment. Specifically, it is concerned with product scheduling by which the inventory control of disassembled parts can be incorporated into a priority rule to reduce part lead times. The part lead time consists of two components: flow time and supply delay. The primary focus of the paper is on the development of a disassembly priority rule that aims to reduce the supply delay. We propose a priority rule, called Minimum Distance (MD) rule, to improve the supply delay performance. Finally, we provide a comparative analysis on the performance of traditional rules and the new rule proposed in this paper via a simulation model.

• Journal of the Korean Dietetic Association
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• v.18 no.2
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• pp.170-185
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• 2012

The purpose of this study was to explore nutrition teachers/dietitians' perception towards production management practices as well as the importance & performance of nutrient preservation during production by school foodservices. A total of 120 school nutrition teachers/dietitians in the Daegu area participated in this study. The data were analyzed by descriptive analysis, t-test, and ANOVA using SPSS/Windows (ver 17.0). A questionnaire consisted of three dimensions with 66 items concerning the general characteristics of schools and respondents, production management practices, and perceived importance and performance of nutrient preservation. Exactly 79.2% of dietitians responded that scheduling of production management is necessary, and 52.5% of respondents perceived that their knowledge for nutrient preservation is of normal/average level. Thirty-eight percent of respondents did not establish scheduling of production management; according to them, cooking stage has priority over other stages of nutrient preservation. Perceived importance score was higher than perceived performance score in all stages of production management. The difference between perceived importance and performance in the production scheduling stage was found to be statistically significant. The results indicate that nutrition control point should be established and managed to prevent nutrient loss in all production stages. Further, dietitians who do not take measures to reduce nutrient loss should be carefully educated on the importance of nutrient control and be motivated to follow guidelines on nutrient preservation.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1993.04a
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• pp.119-119
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• 1993