• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.324-329
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• 2000

Object of a real-time system, that performs exact information based on the real-time constraint. is required for an improvement of high reliability. The fault-tolerant task scheduling strategy of multiprocessor as using a distributed memory based on a hardware redundancy can be improved into a high reliability of the real-time system. Therefore, this paper is shown to analyze the reliability of the system by using the transfer parameter and make the modeling in reference to a minimization of the fault-tolerant task scheduling strategy which uses a percentage of task missing and deadline parameter based on optimization task size.

• 산업경영시스템학회지
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• 제34권4호
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• pp.189-196
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• 2011

In this paper, we propose a logical control-based actor-critic algorithm as an efficient approach for the approximation of the capacitated fab scheduling problem. We apply the average reward temporal-difference learning method for estimating the relative value functions of system states, while avoiding deadlock situation by Banker's algorithm. We consider the Intel mini-fab re-entrant line for the evaluation of the suggested algorithm and perform a numerical experiment by generating some sample system configurations randomly. We show that the suggested method has a prominent performance compared to other well-known heuristics.

• 산업공학
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• 제13권2호
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• pp.266-272
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• 2000

This paper deals with a computer-aided product arrangement system in the plant industry. The arrangement schedule may be performed manually. But this is inadaptable to change and difficult to store the results, which eventually requires time consuming and ineffective works. Using computerbased scheduling system, problems mentioned above can be resolved. In the system, the products can be arranged in a workarea with an automatic algorithm as well as manual operation using mouse dragging. In the automatic scheduling algorithm, the position of a product is determined by considering the existing products and material handling costs. Then the scheduled results are stored in DB and can be manipulated at any time.

• 한국IT서비스학회지
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• 제8권1호
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• pp.179-192
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• 2009

In wireless environments, it is very effective to introduce a data broadcast system for providing a number of clients with mobile data services. In particular, an efficient broadcast scheduling and a caching strategy are very important for performance of data broadcast systems in wireless environments which have such inherent restrictions as low bandwidth, frequent disconnections, and short battery life. In this paper, we present a data broadcast scheduling strategy using bit vectors to cope with dynamic request patterns of clients. In addition, we also propose an efficient caching strategy, 2FWT, that takes characteristics of the broadcast scheduling strategy into account. Finally, we evaluate performance of the data broadcast system. According to the results, the proposed system generally shows better performance than others.

• 국제학술발표논문집
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• The 1th International Conference on Construction Engineering and Project Management
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• pp.643-648
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• 2005

The planning process for roadway construction involves a large amount of information on design, construction methods, quantities, unit costs, production rates, and site conditions. Therefore, it is very important to acquire, manage, and process the necessary information efficiently to produce a rigorous construction plan. GIS (Geographic Information System) is a very effective tool for integrating and managing various types of information including spatial and non-spatial data required for roadway construction planning. This paper proposes a GIS-based system for improving roadway construction planning with its 'Interactive Space Scheduling' and 'Operation Level Planning' functions. The proposed system can assist construction planners in a unique way by integrating design and construction information and creating modularized design elements for space scheduling in real time. It is expected that the proposed system could improve the efficiency of roadway construction planning.

• 산업경영시스템학회지
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• 제38권3호
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• pp.78-86
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• 2015

Up-to-date business environment for manufacturers is very complex and rapidly changing. In other words, companies are facing a variety of changes, such as diversifying customer requirements, shortening product life cycles, and switching to small quantity batch production. In this situation, the companies are introducing the concept of JIT (just-in-time) to solve the problem of on-time production and on-time delivery for survival. Though many companies have introduced ERP (enterprise resource planning) systems and MRP (material requirement planning) systems, the performance of these systems seems to fall short of expectations. In this paper, the case study on introducing an APS (advanced planning and scheduling) system based on dispatching rules to a machining company and on finding a method to establish an efficient production schedule is presented. The case company has trouble creating an effective production plan and schedule, even though it is equipped with an MRP-based ERP system. The APS system is applied to CNC (computer numerical control) machines, which are key machines of the case company. The overall progress of this research is as follows. First, we collect and analyze the master data on individual products and processes of the case company in order to build a production scheduling model. Second, we perform a pre-allocation simulation based on dispatching rules in order to calculate the priority of each order. Third, we perform a set of production simulations applying the priority value in order to evaluate production lead time and tardiness of pre-defined dispatching rules. Finally, we select the optimal dispatching rule suitable for work situation of the case company. As a result, an improved production schedule leads to an increase in production and reduced production lead time.

• 산업공학
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• 제17권spc호
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• pp.111-121
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• 2004

In this paper, we propose an urgency and efficiency based wireless packet scheduling (UEPS) algorithm that is able to schedule real time (RT) and non-real time (NRT) traffics at the same time. The proposed UEPS algorithm is designed to support wireless downlink packet scheduling in the OFDMA system which is a strong candidate wireless system for the next generation mobile communications. The UEPS algorithm uses the time-utility function as a scheduling urgency factor and the relative status of the current channel to the average one as an efficiency indicator of radio resource usage. The design goal of the UEPS algorithm is to maximize throughput of NRT traffics with satisfying QoS requirements of RT traffics. The simulation study shows that the proposed UEPS algorithm is able to give better throughput performance than existing wireless packet scheduling algorithms such as proportional fair (PF) and modified-largest weighted delay first (M-LWDF) while satisfying QoS requirements of RT traffics such as the average delay and the packet loss rate under various traffic loads.

• 정보처리학회논문지A
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• 제10A권3호
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• pp.181-188
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• 2003

본 논문에서는 IRIS(Increasing Reward with Increasing Service) 태스크들을 위한 기존 온-라인 최적 알고리즘에 근접한 총가치(total reward)를 생성하면서 보다 낮은 스케줄링 복잡도를 가진 휴리스틱(heuristic) 온-라인 스케줄링 알고리즘을 제안한다. 기존 알고리즘들은 총가치를 최대화하기 위해 시스템 내의 모든 태스크들을 스케줄링 대상으로 고려한다. 따라서 이들 알고리즘들은 많은 태스크들을 가진 실제 시스템에 적용하기에는 매우 놀은 시간 복잡도를 가진다. 제안 알고리즘은 시스템 내의 모든 태스크들을 대상으로 스케줄링하는 것이 아니라, 상수 W개의 태스크들을 선택하여 이들을 대상으로 스케줄링 한다. 제안 알고리즘은 W개의 태스크를 어떤 기준에 의해 선택할 것인가를 규정하는 테스크 선택정책에 기반을 두고 있으며, 간단하면서도 직관적인 두 가지 선택정책과 이 둘을 통합한 보다 일반화된 선택정책을 제안한다. 스케줄링 대상을 축소함으로써 제안 알고리즘의 복잡도를 O(Wn)로 줄일 수 있었다. 다양한 성능실험 결과 알고리즘 평균 계산 빈도는 O(W)에 더 가깝다는 것을 확인할 수 있었다.

• 컴퓨터교육학회논문지
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• 제18권3호
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• pp.115-124
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• 2015

본 논문에서는 그리드 시스템의 스케줄링 알고리즘을 시뮬레이션 할 수 있는 웹 기반의 스케줄링 툴킷(GridTool2)를 소개한다. 그리고 기존 MinMin과 Suffrage 스케줄링 알고리즘에 통신비용을 적용하여 성능이 향상된 수정 알고리즘을 제안한다. GridTool2는 서버와 데이터베이스를 기반으로 웹 환경에서 동작하므로 별도의 컴파일이나 실행 환경을 구축하지 않아도 된다. GridTool2는 통신비용과 함께 성능분석을 위한 변수들을 웹에서 입력하며, 시뮬레이션 결과를 웹페이지에 나타낸다. 통신비용을 적용한 수정된 알고리즘의 향상된 성능을 확인하기 위하여 GridTool2를 사용하여 실험하였다. 실험 결과에 따르면 기존 알고리즘보다 통신비용을 고려한 수정 알고리즘의 성능이 향상되었으며, 특히 작업량이 많아지면 성능향상의 폭이 증가하는 것으로 확인되었다.

• 한국콘텐츠학회논문지
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• 제9권12호
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• pp.52-63
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• 2009

본 논문에서는 유니폼 멀티프로세서 환경에서 단순 주기성 태스크 시스템을 성공적으로 스케줄 할 수 있는 알고리즘을 제안한다. 멀티프로세서 환경에서 주기성 태스크를 스케줄하기 위한 파티션드(partitioned) 스케줄링 알고리즘은 bin-packing 문제와 같은 문제로써 해결하는 게 불가능하다고 알려져 있다. 본 논문에서는 "task-splitting"기법을 이용하여 단순 주기성 태스크 시스템을 다른 단순 주기성 태스크 시스템으로 변환하는 글로벌(global) 스케줄링 알고리즘을 제시하고, 변환과정을 거친 단순 주기성 태스크 시스템은 유니폼 멀티프로세서에서 파티션드 스케줄링 알고리즘에 의해 성공적으로 스케줄 된다. 그리고 유니폼 멀티프로세서 환경에서 제안한 알고리즘이 이론적으로 최대 이용률 범위(utilization bound)까지 성공적으로 스케줄 할 수 있음을 증명한다.