• Journal of the Korean Operations Research and Management Science Society
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• v.23 no.4
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• pp.33-51
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• 1998

The industrial operation is one of the three basic modes of shipping operation with liner and Tramp operations. Industrial operators usually control vessels of their own or on a time charter to minimize the cost of shipping their cargoes. Such operations abound in shipping of bulk commodities, such as oil, chemicals and ores. This work is concerned with an operational optimization analysis of the fleet owned by a major oil company. a typical industrial operator. The operational optimization problem of the fleet of a major oil company is divided Into two phase problem. The front end corresponds to the optimization problem of the transportation of crude oil. product mix. and the distribution of product oil to comply with the demand of the market. The back end tackles the scheduling optimization problem of the fleet to meet the seaborne transportation demand derived from the front end. A case study reflecting the practices of an international major oil company is demonstrated to make clear the underlying ideas.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.339-343
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• 2004

In this paper, we propose a cell scheduling scheme which can improve the fairness and the goodput through the traffic control in GFR service. For the evaluation of the proposed scheme, we compare the proposed scheme with the existing scheme in the fairness and the goodput. Simulation results show that proposed scheme can improve the fairness and goodput comparing with the existing buffer management scheme.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.476-486
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• 1995

In this paper, an attempt has been made to revise Raafat' s(1985) results on an inventory model for decaying raw materials and the finished product at a constant rate which was based on Goyal's integrated inventory model for a single product system. This paper is concerned with scheduling the frequencies of order quantity of several different raw materials on a production inventory model. The purpose of this paper is to present a simple method of deciding the frequencies of order quantity of raw materials, in the sense of minimizing the average total cost of the system. We describe on iterative procedure for directly determining near optimal frequencies of order quantity for the raw materials and the associated fundamental cycle time which can be used for constructing the production duration of the finished product. In cases where feasible schedules cannot be constructed using the values from the iterative procedure, the procedure provides a basis for changing the order quantity frequencies and the fundamental cycle time to obtain feasible schedules. An example is given to illustrate the derived results.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.14-35
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• 1991

The purpose of this study is to develop an efficient exact algorithm for the problem of scheduling n in dependent jobs on m unequal parallel processors to minimize makespan. Efficient solutions are already known for the preemptive case. But for the non-preemptive case, this problem belongs to a set of strong NP-complete problems. Hence, it is unlikely that the polynomial time algorithm can be found. This is the reason why most investigations have bben directed toward the fast approximate algorithms and the worst-case analysis of algorithms. Recently, great advances have been made in mathematical theories regarding Lagrangean relaxation and the subgradient optimization procedure which updates the Lagrangean multipliers. By combining and the subgradient optimization procedure which updates the Lagrangean multipliers. By combining these mathematical tools with branch-and-bound procedures, these have been some successes in constructing pseudo-polynomial time algorithms for solving previously unsolved NP-complete problems. This study applied similar methodologies to the unequal parallel processor problem to find the efficient exact algorithm.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.13-35
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• 1991

The purpose of this study is to develop an efficient exact algorithm for the problem of scheduling n in dependent jobs on m unequal parallel processors to minimize makespan. Efficient solutions are already known for the preemptive case. But for the non-preemptive case, this problem belongs to a set of strong NP-complete problems. Hence, it is unlikely that the polynomial time algorithm can be found. This is the reason why most investigations have bben directed toward the fast approximate algorithms and the worst-case analysis of algorithms. Recently, great advances have been made in mathematical theories regarding Lagrangean relaxation and the subgradient optimization procedure which updates the Lagrangean multipliers. By combining and the subgradient optimization procedure which updates the Lagrangean multipliers. By combining these mathematical tools with branch-and-bound procedures, these have been some successes in constructing pseudo-polynomial time algorithms for solving previously unsolved NP-complete problems. This study applied similar methodologies to the unequal parallel processor problem to find the efficient exact algorithm.

• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.4
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• pp.115-131
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• 1997

The problem addressed in this paper is to minimize the deviations of workloads assigned to worker and to maximize the total utilizations(degree of skill) between workers and machines simultaneously. Each worker can handle the set of machines with the different degree of skill and each machine has the workloads needed to be processed. Also, each worker has to be assigned to at least one machine with the minimum workload deviation. This problem can be formulated as a preemptive goal programming with generalized assignment constraints. The proposed algorithm consists of two phases. First, a capacitated circulation network is constructed to assign the workers to machines with the maximum total utilizations while considering workloads balance. Then, a refinement process is applied to the split machines to satisfy the feasibility condition. The real industrial application in a plastic extrusion manufacturer is included along with several computational experiments.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.157-160
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• 1998

통합생산시스템의 최적설계를 위하여 이의 생산공정(Manufacturing Process)과 물류시스템 (Material Handling System)은 두 가지 중요한 요소이다. 본 연구에서는 물류시스템의 성능 및 비용을 분석을 위하여 제품의 생산계획(Production Control & Scheduling), 설비배치(Layout) 및 물류시스템 (Material Handling System) 등을 고려하였다. 본 연구의 주요 목적을 통합생산시스템을 위하여 물류시스템 성능의 최적화와 경제적인 분석을 통하여 최적 물류시스템의 선택에 두고 다음 주요 내용들을 포함하였다; 1) 주요 입력 자료로서 통합생산 장비의 배치(Layout), 공정, 생산제품의 예측, 물류시스템 대안 등이 주어지고, 2) 이를 이용하여 각 물류시스템의 대안별 성능 및 비용 등을 비교 분석하고 최적 물류시스템을 선정한다. 본 연구를 위한 성능 및 비용분석을 위한 전산프로그램을 개발하고 이를 활용한 사례를 들어 보였다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2008.10a
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• pp.299-303
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• 2008

In this paper, we discuss the schedule problems for Korean Professional Baseball League (KPBL) and propose approaches to solve these problems by applying Integer Programming. A schedule in a sport league must satisfy lots of constraints on timing such as organizational, attractiveness, and fairness requirements. Organizational requirements cover a set of rules which have to guarantee that all the games can be scheduled according to the regulations imposed by Korean Baseball Organization (KBO). Attractiveness requirements focus on what stadium visitors, television spectators, and the clubs expect, that is, a varied, eventful, and exciting season. Fairness requirements have to guarantee that no team is handicapped or favored in comparison with the others. In addition to finding a feasible schedule that meets all the constraints, the problem addressed in this paper has the additional complexity of having the objective of minimizing the travel costs and every team has the balancing number of the games in home. We formalize the KPBL problem into an optimization problem and adopt the concept of evolution strategy to solve it. Using the method proposed, it is efficient to find better results than approaches developed before.

• Proceedings of the Safety Management and Science Conference
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• 2000.05a
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• pp.55-60
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• 2000

In recent dates, Internet advertising effects are expanded by the steep increment of the Internet users and the extension of the advertising market will be accelerated through Internet. This paper indicates the importance of Internet advertising and suggests the solution of a network advertising service. The system Is divided into an Advertise Server, an Advertiser and a Web Publisher. This study proposes both the collection and the analysis of traffic data in real time. Also, the banner advertising frames are smoothed for the impression using the solution for the banner exchange engine and are developed using various impression methods, that is, Fixed/variable Banner, Scheduling Banner, Multi-Impression Banner, and Frame Remote Control to increase the advertising effect. And then to increase the advertising effect web publisher, which is specialized in lottery site, is constructed using the network advertising service and various advertising technology.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.534-537
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• 2000

Recently, A manufacturing formula centered of the customer is one of the most important parts for the company competition. Especially, it is the matters of weight and importance that Make to Order(MTO) and Make to stock(MTS) is considered at the same time for designing manufacturing system based the order effectly. This paper suggests a alternative Available to promise(ATP) and capable to promise(CTP) to confirm the delivery time to customer, how to link mid-long term production plan with short term daily based scheduling, how to relate middle processes of device based industry to mid-long term plan through the example of S company in a manufacturing formula mixed MTO and MTS