• 한국CDE학회논문집
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• 제19권3호
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• pp.236-244
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• 2014

Presented in the paper is a reservation based dispatching rule to achieve the on-time delivery in system LSI (large scale integrated circuit) semiconductor fabrication (FAB) with urgent orders. Using the proposed reservation based dispatching rule, urgent lots can be processed without waiting in a queue. It is possible to achieve the on-time delivery of urgent orders by reserving a proper tool for the next step in advance while urgent lots are being processed at the previous step. It can cause, however, tardiness of normal lots, because the proposed rule assign urgent lots first. To solve this problem, the proposed rule tries to find the best tool for the reservation in the tool group, which can minimize idle time, and the reservation rule is applied at all tools except for photolithography tools (bottleneck). $MOZART^{(R)}$ which is developed by VMS solutions are used for simulation experiments. The experimentation results show that the reservation based dispatching rule can achieve the on-time delivery of normal lots as well as urgent lots.

• 한국시뮬레이션학회논문지
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• 제7권1호
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• pp.39-51
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• 1998

In this paper, MVED (Minimum Vehicle's Empty Distance), a new dispatching rule for a Single Loop-Single Vehicle AGV system, is developed. Single Loop-Single Vehicle AGV system consists of segmented bi-directional single loops, in which only one AGV is assigned. The MVED rule is focused on minimizing vehicles empty travel distance. Using simulation, the performance of the MVED is compared with that of existing dispatching rules such as STT/D and MEVTT. The results show MVED rule's better performance than others. ARENA is used as a simulation language.

• International Journal of Quality Innovation
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• 제8권2호
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• pp.132-146
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• 2007

Constructing an effective production control policy is the most important issue in wafer fabrication factories. Most of researches focus on the input regulations of wafer fabrication. Although many of these policies have been proven to be effective for wafer fabrication manufacturing, in practical, there is a need to help operators decide which lots should be pulled in the right time and to develop a systematic way to alleviate the long queues at the bottleneck workstation. The purpose of this study is to construct a photolithography workstation dispatching rule (PADR). This dispatching rule considers several characteristics of wafer fabrication and influential factors. Then utilize the weights and threshold values to design a hierarchical priority rule. A simulation model is also constructed to demonstrate the effect of the PADR dispatching rule. The PADR performs better in throughput, yield rate, and mean cycle time than FIFO (First-In-First-Out) and SPT (Shortest Process Time).

• 한국시뮬레이션학회논문지
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• 제23권4호
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• pp.97-109
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• 2014

Personal Rapid Transit (PRT)는 차세대 대중교통 수단으로 에너지 효율적이며 높은 수준의 고객 서비스를 제공한다. 정류장에 동적으로 도착한 고객이 운송 서비스를 요청하면 PRT 시스템은 차량을 배차한다. 본 연구에서는 PRT 시스템을 위한 새로운 온라인 배차 알고리즘을 제시하였다. 제시된 알고리즘은 최근린(nearest neighbor) 배차 규칙을 기반으로 개발되었으며, 이분 매칭(bipartite matching)을 사용하여 다수의 PRT 차량과 고객을 동시에 고려하여 배차를 결정한다. 이 경우 전체 차량 중 배차 대상 차량의 선택 범위가 성능지표에 영향을 줄 수 있다. 따라서 본 연구에서는 차량의 상태를 고려하여 체계적으로 배차 차량을 선택하는 방법을 제시한다. 성능지표로 공차 이동거리와 고객 대기시간을 고려하였으며, 시뮬레이션 기법을 사용하여 배차 선택 범위에 따른 성능지표의 차이를 확인하였다. 그리고 기존의 배차 규칙과 비교하여 본 연구에서 제시하는 방법론이 우수하며 PRT 시스템에 적합한 것을 확인하였다.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2001년도 The Pacific Aisan Confrence On Intelligent Systems 2001
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• pp.25-29
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• 2001

There are so many researches about the search method for the most compatible dispatching rule to a manufacturing system state. Most of researches select the dispatching rule using simulation results. This paper touches upon two research topics: the clustering method for manufacturing system states using simulation, and the search method for the most compatible dispatching rule to a manufacturing system state. The manufacturing system state variables are given to ART II neural network as input. The ART II neural network is trained to cluster the system state. After being trained, the ART II neural network classifies any system state as one state of some clustered states. The simulation results using clustered system state information and those of various dispatching rules are compared and the most compatible dispatching rule to the system state is defined. Finally there are made two knowledge bases. The simulation experiments are given to compare the proposed methods with other scheduling methods. The result shows the superiority of the proposed knowledge base.

• 한국시뮬레이션학회논문지
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• 제9권3호
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• pp.77-89
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• 2000

This paper suggests a multi-attribute dispatching rule for an automated guided vehicle(AGV). The attributes to be considered are the number of queues in outgoing buffers of workstations, distance between an idle AGV and a workstation with a job waiting for the service of vehicle, and the number of queues in input buffers of the destination workstation of a job. The suggested rule is based on the simple additive weighting method using a normalized score for each attribute. A neural network approach is applied to obtain an appropriate weight vector of attributes based on the current status of the manufacturing system. Backpropagation algorithm is used to train the neural network model. The proposed dispatching rules and some single attribute rules are compared and analyzed by simulation technique. A number of simulation runs are executed under different experimental conditions to compare the several performance measures of the suggested rules and some existing single attribute dispatching rules each other.

• 한국전자파학회논문지
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• 제23권1호
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• pp.1-13
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• 2012

능동 위상 배열레이더(AESA radar: Active Electronically Scanned Array radar)는 전자적으로 빔을 조향함으로써 빔 조향 시간이 비약적으로 빨라져, 기존의 기계식 빔 조향 레이더에 비해 레이더에서 수행할 수 있는 다중 임무처리 능력이 크게 향상되었다. 이러한 다중 임무 처리 능력을 최대화하면서 레이더의 전체 성능을 향상하기 위해, 레이더에 주어진 시간, 에너지, 처리 능력 등의 한정된 자원을 실시간으로 효율적으로 관리, 운용할 수 있는 레이더 자원 관리 기술의 중요성이 크게 대두되었다. 그 중 레이더 빔 스케줄링 기술은 레이더 자원 관리의 핵심적인 요소라 할 수 있다. 본 논문에서는 레이더 빔 스케줄링을 위한 다양한 dispatching rule을 비교 분석하고, 특히 빔의 처리 시간 지연 정도에 따라 SPF(Shortest Processing time First)와 ERF(Earliest Request time First)를 차등적으로 적용하여 빔의 우선 순위를 정하는 dispatching rule을 제안, 그 성능의 우월성을 입증하였다.

• 한국시뮬레이션학회논문지
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• 제9권1호
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• pp.21-38
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• 2000

A fuzzy dispatching algorithm with adaptable control scheme is proposed for more flexible and adaptable operation of AGV system. The basic idea of the algorithm is prioritization of all move requests based on the fuzzy urgency. The fuzzy urgency is measured by the fuzzy multi-criteria decision-making method, utilizing the relevant information such as incoming and outgoing buffer status, elapsed time of move request, and AGV traveling distance. At every dispatching decision point, the algorithm prioritizes all move requests based on the fuzzy urgency. The performance of the proposed algorithm is compared with several dispatching algorithms in terms of system throughput in a hypothetical job shop environment. Simulation experiments are carried out varying the level of criticality ratio of AGVs , the numbers of AGVs, and the buffer capacities. The rule presented in this study appears to be more effective for dispatching AGVs than the other rules.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 춘계학술대회 및 창립 30주년 심포지엄(논문집)
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• pp.345-348
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• 2006

LMTT (linear motor-based transfer technology) is horizontal transfer system in the maritime container terminal for the port automation. For LMTT system, shuttle cars are used instead of other types of cars. They are running on the routes which are stable on the terminal ground made of steel. The terminal scheduling complexity increases with the need of improving automation. It is necessary to make a good designed performance for the terminal system. This work presents a dispatching role using fuzzy logic for the shuttle cars. It considers the actual status of terminals and takes decisions on real time. A simulation is done to validate the role and two other dispatching rules to be compared.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2011년도 춘계학술대회
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• pp.218-219
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• 2011

본 논문은 컨테이너 운송을 위한 AGV(Automated Guided Vehicle) 배차 전략을 대상으로 한다. AGV 배차 문제는 안벽 크레인의 대기 시간과 AGV의 주행 거리를 최소화하도록 AGV에 작업을 할당하는 것이 목표이다. 터미널 환경의 동적인 특성으로 인해 계획 결과의 정확한 예측이 어렵고 수정이 빈번하기 때문에 실무에서는 의사결정 시간이 짧은 단순 규칙 기반 배차가 많이 쓰인다. 그러나 단순 규칙 기반 배차는 근시안적 특성으로 인해 배차의 다양한 성능 지표를 만족시키지 못하는 한계가 있으며 이를 극복하기 위해 본 논문에서는 복수 규칙 기반의 배차 전략을 제안한다. 복수 휴리스틱 기반 배차 전략은 여러 규칙의 가중합으로 구성되며 규칙 사이의 가중치를 최적화하기 위해 다목적 진화 알고리즘을 적용하였다. 시뮬레이션 실험을 통해 제안 방안이 기존 단일 규칙 기반 배차에 비해 더 좋은 성능을 보임을 확인하였다.