• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1993년도 춘계공동학술대회 발표논문 및 초록집; 계명대학교, 대구; 30 Apr.-1 May 1993
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• pp.343-352
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• 1993

In this study, a modified algorithm for the exchange heuristic is developed and applied to a resource-constrained scheduling problem. The problem involves multiple projects and multiple resource categories and allows flexible resource allocation to each activity. The objective is to minimize the maximum completion time. The exchange heuristkc is a multiple pass algorithm which makes improvements upon a given initial feasible schedule. Four different modified algorithms are proposed. The original algorithm and the new algorithms were compared through an experimental investigation. All the proposed algorithms reduce the maximum completion time much more effectively than the original algorithm. Especially, one of four proposed algorithms obviously outperforms the other three algorithms. The algorithm of the best performance produces significantly shorter schedules than the original algorithm, though it requires up to three times more computation time. However, in most situations, a reduction in schedule length means a significant reduction in the total cost.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.431-432
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• 2008

We propose a DVS technique for multiprocessor systems considering the energy consumed when translating voltage. We schedule periodic applications on two identical processors throughout a three-stage process; firstly, the computation energy consumption is minimized then the number of voltage translations is minimized. Finally, the result is compared with the schedule with no voltage translation and the one with smaller energy consumption is chosen. Overall, 10.6% energy reduction was achieved.

• 산업경영시스템학회지
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• 제29권1호
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• pp.109-115
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• 2006

Exact solutions for practical-size problems in job shop will be highly inefficient. Scheduling heuristics, therefore, are typically found in the literature. If we consider real-life situations such as machine breakdowns, the existing scheduling methods will be even more limited. Scheduling against due-dates addresses one of the most critical issues in modern manufacturing systems. In this paper, the method for weighted tardiness schedule using a graph theoretic decomposition heuristic is presented. It outstands the efficiency of computation as well as the robustness of the schedule.

• 대한산업공학회지
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• 제27권2호
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• pp.158-168
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• 2001

We present a tabu search (TS) algorithm to minimize maximum lateness on a single machine in the presence of sequence dependent setup times and dynamic job arrivals. The TS algorithm starts with a feasible schedule generated by a modified ATCS (Apparent Tardiness Cost with Setups) rule, then through a series of search steps it improves the initial schedule. Results of extensive computational experiments show that the TS algorithm significantly outperforms a well-known RHP heuristic by Ovacik and Uzsoy, both on the solutions quality and the computation time. The performance advantage is particularly pronounced when there is high competition among jobs for machine capacity.

• 대한산업공학회지
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• 제18권1호
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• pp.91-104
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• 1992

Flowshop scheduling problem is known to be NP-complete. Since the optimization apporach like branch-and-bound is limited by exponentially growing computation time, many heuristic methods have been developed. Total tardiness is one of the criteria that the researchers have recently considered in flowshop scheduling. There, however, are few literatures which studied the general (m machine)-flowshop scheduling under the total tardiness criterion. In this paper, a heuristic scheduling method to minimize total tardiness at the (m machine, n job)-flowshop is presented. A heuristic value function is proposed to be used as a dispatching criterion in initial schedule generation. And the schedule improving procedure, by pairwise interchange of tardy job with the job right ahead of it, is introduced. Illustrative examles and simulated results are presented.

• Journal of Information Processing Systems
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• 제10권2호
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• pp.193-214
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• 2014

Load balancing is the major benefit of any distributed system. To facilitate this advantage, task duplication and migration methodologies are employed. As this paper deals with dependent tasks (DAG), we used duplication. Task duplication reduces the overall schedule length of DAG along-with load balancing. This paper proposes a new task duplication algorithm at the time of tasks assignment on various processors. With the intention of conducting proposed algorithm performance computation; simulation has been done on the Netbeans IDE. The mesh topology of a distributed system is simulated at this juncture. For task duplication, overall schedule length of DAG is the main parameter that decides the performance of a proposed duplication algorithm. After obtaining the results we compared our performance with arbitrary task assignment, CAWF and HEFT-TD algorithms. Additionally, we also compared the complexity of the proposed algorithm with the Duplication Based Bottom Up scheduling (DBUS) and Heterogeneous Earliest Finish Time with Task Duplication (HEFT-TD).

• 한국건설관리학회논문집
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• 제13권2호
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• pp.120-127
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• 2012

오늘날 대부분의 건설 사업들은 점차 프로젝트의 규모가 고층화, 대형화, 복잡화되어 가고 있다. 이에 국내 건설기업들은 전체적인 공사 흐름을 파악하고 공정의 연결 관계를 고려하는 등 체계적이고 효율적인 공정관리를 위해 여러 가지 관리기법 및 도구들을 개발하여 실무에 도입하고 있다. 그러나 기존의 공정관리 소프트웨어들은 대부분 ADM, PDM기법을 기반으로 하고 있기 때문에 실무 적용 시 많은 문제점들을 발생시키고 있다. 그 중 PDM기법은 선 후행 작업의 착수시점과 완료시점 간의 조합만으로 작업 간의 중복관계를 우회적으로 표현하기 때문에 매우 비효율적이다. 이러한 기존 CPM기법의 단점을 보완하기 위해 직접적으로 작업 간 양방향 다중 중복관계를 표현할 수 있는 새로운 CPM 공정관리기법인 BDM(Beeline Diagramming Method)기법이 제안되었다. 그러나 양방향 다중 중복관계를 표현하고 일정계산을 하게 되면 루프(Loop)현상이 발생하게 된다. 본 연구에서는 BDM기법의 일정계산 방법에 대해 연구하여 양방향 다중 중복관계에서 루프가 발생했을 때 일정계산을 원활하게 할 수 있는 방법에 대해 제안 및 검증을 하고자 한다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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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.

• 산업경영시스템학회지
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• 제17권32호
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• pp.63-71
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• 1994

The purpose of this paper is to describe an effective cell scheduling system for flexible manufacturing cells. Based on the FMC characteristics, cell scheduling can be defined as a dynamic modified flow shop working in a real-time system. This paper attempt to find the optimal cell scheduling when minimizing the mean flow time for n-job/m-machine problems in static and dynamic environments. Real-time scheduling in an FMC environment requires rapid computation of the schedule.

• 연구논문집
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• 통권30호
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• pp.5-13
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• 2000

The computation scheme of simulating gas turbine transient behavior was developed. The basic principles of this scheme and main input data required are described. Calculation results are presented in terms of whole operating regime of the cycle. The influence of main initial parameters such as starting engine power, moment of inertia of the rotor, fuel supplying schedule etc. on performance characteristics of has turbine during transient operation is studied In addition, bleeding air influence on transient behavior was also considered For validation of the developed code, comparison of present calculation with that of measurement data of the experimental data for the range of operating period studied.