• 산업경영시스템학회지
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• 제23권59호
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• pp.21-36
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• 2000

The drum-buffer-rope(DBR) system is a finite scheduling mechanism that balances the flow of the production system. DBR controls the flow of materials through the plant in order to produce products in accordance with market demand, with a minimum of manufacturing lead time, inventory, and operating expenses. This paper integrates the best of MRP push system and JIT pull system with DBR system, efficiently adapts these logics to capacity constraint resources, and contributes to the evolution of synchronous manufacturing. The purpose of this paper is, thus, threefold. The first objective is to identify the frame of theory of constraints(TOC) and the logic of DBR scheduling. The second objective is to formulate the DBR constraint scheduling problems(DBRCSP) in a job shop environments. Finally, the paper is to suggest the solution procedure of DBRCSP for embedding TOC into MRP/JIT along with an numerical expression. In addition, illustrative numerical example is given.

• 에너지공학
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• 제7권1호
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• pp.81-88
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• 1998

본 논문은 전력회사 소유의 열병합발전소와 난방공사 소유의 보조열원설비들이 서로 연계되어 열에너지를 공급해 주고 있는 종합 열병합발전시스템에서, 보조설비들의 최적규모산정 및 일간 최적운전계획 수립 기법을 제안하였다. 최적규모산정과 운전계획수립은 국가적인 측면에서 총 연료비가 최소가 되는 관점에서 수립하였고, 이를 증명하기 위하여 계절별(춘계, 하계, 동계) 및 종류별(평일, 휴일, 연휴)로 나누어 각각의 시뮬레이션 결과로부터 최적의 규모 및 운전계획을 수립하였다. 본 연구결과는 자사의 이익이 증대되도록 계획을 수립할 공산이 큰 종합 열병합발전시스템에서 국가적 측면에서의 기법과 가이드라인을 제시하였으므로 현장에서의 많은 활용이 기대된다.

• 한국컴퓨터산업학회논문지
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• 제2권9호
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• pp.1225-1232
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• 2001

본 논문에서는 광역 ATM 망에서 인터넷 서비스를 제공하기 위하여 입력 소스 트래픽의 QoS 등급에 기초한 라우터 시스템에 적용되는 다양한 스케줄링 알고리즘들을 분석하고 서비스 특성에 따라 QoS 요구사항을 보장할 수 있는 새로운 스케줄링 알고리즘을 제안한다. 이를 위하여, 인터넷망에서의 패킷 다중화기의 요구사항을 살펴보고 실시간 서비스제공을 위한 패킷 다중화기의 기능 구조와, 다양한 QoS를 만족시키기 위한 스케줄링 알고리즘을 설계한다. 마지막으로 모의 실험을 통해 평균 지연 시간 및 망 자원 활용의 공평성 측면에서 알고리즘의 성능을 고찰한다.

• Journal of Communications and Networks
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• 제5권3호
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• pp.230-239
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• 2003

In this paper, we propose a framework to study how to route packets efficiently in multipath communication networks. Two traffic congestion control techniques, namely, flow assignment and packet scheduling, have been investigated. The flow assignment mechanism defines an optimal splitting of data traffic on multiple disjoint paths. The resequencing delay and the usage of the resequencing buffer can be reduced significantly by properly scheduling the sending order of all packets, say, according to their expected arrival times at the destination. To illustrate our model, and without loss of generality, Gaussian distributed end-to-end path delays are used. Our analytical results show that the techniques are very effective in reducing the average end-to-end path delay, the average packet resequencing delay, and the average resequencing buffer occupancy for various path configurations. These promising results can form a basis for designing future adaptive multipath protocols.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.76-79
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• 2002

In this paper, we propose a Probabilistic Tabu Search(PTS) method for hydro-thermal scheduling. Hydro scheduling has many constraints and very difficult to solve the optimal schedule because it has many local minima. To solve the problem effectively, the proposed method uses two procedures, one is Tabu search procedure that plays a role in local search, and the other is Restarting procedure that enables to diversify its search region. To adjust parameters such as a reducing rate and initial searching region, search strategy is selected according to its probability after Restarting procedure. In order to show the usefulness of the proposed method, the PTS is applied on two cases which have dependent hydro plants and compared to those of other method. The simulation results show it is very efficient and useful algorithm to solve the hydro-thermal scheduling problem.

• 한국경영과학회지
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• 제21권2호
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• pp.171-186
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• 1996

This paper comes from an observation that overemphasis on capacity utilization meausre, which is usual under capacity shortage, can seriously hurt the firm's profit and potential process improvement. We suggest a model that can be used in designing a coordination scheme for decentralized marketing and manufacturing activities. Using a price and time-sensitive demand and capacitated lotsizing model, we derive an effective communication medium betwen marketing and manufacturing. This Balance Indicator of process capacity and flexibility also implies that the increase in capacity availability and setup time reduction should be balanced by its market requirements. This is particularly important when a firm tries to improve its process capability by kaizen. Further, the model can be used to show the comparative performances of scheduling policies under capacity imbalnce. We show the shortening the scheduling cycle can improve the firm profit without changing the simple scheduling rule.

• 산업경영시스템학회지
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• 제13권21호
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• pp.143-151
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• 1990

This paper studies a single machine scheduling problem in which all jobs have the common due date and penalties are assessed for jobs at different rates. The scheduling objective is to minimize the weighted mean absolute deviations(WMAD). This problem may provide greater flexibility in achieving scheduling objectives than the mean absolute deviation (MAD) problem. We propose three heuristic solution methods based on several dominance conditions. Numerical examples are presented. This article extends the results to the problem to the problem of scheduling n-jobs on m-parallel identical processors in order to minimize the weighted mean absolute deviation.

• 대한안전경영과학회지
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• 제11권3호
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• pp.131-138
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• 2009

This paper considers a coordinated scheduling problem between multi-suppliers and an manufacture. When the supplier has insufficient inventory to meet the manufacture's order, the supplier may use the expedited production and the expedited transportation. In this case, we consider a scheduling problem to minimize the total cost of suppliers and manufacture. We suggest an population management genetic algorithm with local search and crossover (GALPC). By the computational experiments comparing with general genetic algorithm, the objective value of GALPC is reduced by 8% and the calculation time of GALPC is reduced by 70%.

• ETRI Journal
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• 제26권2호
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• pp.185-188
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• 2004

In this paper, we design a two-step scheduling algorithm to support multiple bandwidth allocation policies for upstream channel access in an Ethernet passive optical network. The proposed scheduling algorithm allows us a simultaneous approach for multiple access control policies: static bandwidth allocation for guaranteed bandwidth service and dynamic bandwidth allocation for on-demand, dynamic traffic services. In order to reduce the scheduling complexity, we separate the process of the transmission start- time decision from the process of grant generation. This technique does not require the timing information of other bandwidth allocation modules, so respective modules are free from a heavy amount of timing information or complex processing.

• 전기학회논문지
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• 제56권11호
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• pp.1892-1902
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• 2007

This paper presents a new generating unit maintenance scheduling algorithm considering regional reserve margin and transfer capability. Existing researches focused on reliability of the overall power systems have some problems that adequate reliability criteria cannot be guaranteed in supply shortage regions. Therefore specific constraints which can treat regional reserve ratio have to be added to conventional approaches. The objective function considered in this paper is the variance (second-order momentum) of operating reserve margin to levelize reliability during a planning horizon. This paper focuses on significances of considering regional reliability criteria and an advanced hybrid optimization method based on PSO algorithm. The proposed method has been applied to IEEE reliability test system(1996) with 32-generators and a real-world large scale power system with 291 generators. The results are compared with those of the classical central maintenance scheduling approaches and conventional PSO algorithm to verify the effectiveness of the algorithm proposed in this paper.