• 산업경영시스템학회지
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• 제34권1호
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• pp.1-8
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• 2011

Controlling industrial vehicle operated by human in warehouse was not simple since the information transfer for controlling the vehicle was not easy. However, as the technology for the WMS (Warehouse Management System) has been advanced and the PDA (Personal Digital Assistant) has come into wide use in a workplace, the control of man-operated vehicle became less difficult as do to AGVS (Automated Guided Vehicle System). This study examines the ways to improve the efficiency of warehouse operation through introducing rule of task assignment for the vehicles, particularly forklift. This study, basically, refer to AGV operation policy because a great number of studies for AGV dispatching rule have been done and the mechanism for the controlling vehicles is very similar. The workers in field prefer to simple dispatching rules such as Shortest Retrieval Time First (SRTF), Shortest Travel Time First (STTF), and Longest Waiting Time First (LWTF). However, these rules have potential disadvantage. Thus, several rules made up by combining rules mentioned above are introduced and these new rules use threshold value or evaluation formula. The effectiveness of these new rules are tested by simulation and the results are compared. This study proposes favorable dispatching rules for forklift in warehouse for the efficiency of the vehicle operation and stability of service level.

• 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.

• 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.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1997년도 춘계 학술대회 발표집
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• pp.124-127
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• 1997

A key element in the control of Automated Guided Vehicle Systems (AGVS) is dispatching policy. This paper proposes a new dispatching algorithm for an efficient operation of AGVS. Based on an evolutionary operation, it has an adaptive control capability responding to changes of the system environment. The performance of the algorithm is compared with some well-known dispatching rules in terms of the system throughput through simulation. Sensitivity analysis is carried out varying the buffer capacity and the number of AGVS.

• 산업공학
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• 제16권spc호
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• pp.93-98
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• 2003

This paper addresses an AGV dispatching problem in semiconductor clean-room bays where AGVs move cassettes of wafers between machines or machines and a central buffer. Since each machine in a bay has a local buffer of limited capacity, material flow should be controlled in a careful way to maintain high system performance. It is regarded that two most important performance measures in a semiconductor bay are throughput rate and lead-time. The throughput rate is determined by a bottleneck resource and the lead-time depends on smooth material flow in the system. This paper presents an AGV dispatching procedure based on the concept of theory of constraints (TOC), by which dispatching decisions are made to utilize the bottleneck resource at the maximum level and to smooth the flow of material. The new dispatching procedure is compared with existing dispatching rules through simulation experiments.

• 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.

• 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.

• 산업공학
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• 제17권2호
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• pp.233-241
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• 2004

The main subject to become a hub port is automation. The automated container terminal has already operated in advanced ports and it has been planned for the basic planning and operation design in domestic case. The key of automated container terminal is effective operation of both ATC(automated transfer crane) and AGV(automated guided vehicle) which is automated handling equipments. This is essential to productivity of automated container terminal. This study suggests the most optimal method of equipment operation in order to minimize loading time using each three types of effective ATC operation methods and AGV dispatching rules in automated container terminals. As the automated equipment operation causes unexpected deadlocks or interferences, it should be proceeded on event-based real time. Therefore we propose the most effective ATC operation methods and AGV dispatching rules in this paper. The various states occurred in real automated container terminals are simulated to evaluate these methods. This experiment will show the most robust automated equipment operation method on various parameters(the degree of yard re-marshaling, the number of containers and AGV)

• 대한산업공학회지
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• 제23권2호
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• pp.343-357
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• 1997

This paper proposes a new AGV dispatching algorithm which is suitable for heterarchical manufacturing control structure. It is developed on the basis of bidding concept utilizing the information of work-in-process in incoming and outgoing buffers of workstation, and travel time of AGV. Since the bidding functions are functions of two parameters, sensitivity test is performed to find their appropriate values. The performance of the algorithm is compared with those of well-known existing rules in terms of system throughput through simulation on a hypothetical job shop type manufacturing system.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2007년도 추계학술대회 및 제23회 정기총회
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• pp.216-218
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• 2007

세계 선진항만은 해운물류시장의 변화에 대응하고, 경쟁력 확보 방안으로 첨단 자동화 장비와 운영시스템 도입을 통한 자동화를 지향하고 있다. 국내 부산항 신항 또한 자동화 컨테이너터미널로 개발을 추진하고 있는 것으로 알려져 있다. 자동화 터미널은 각종 자동화 장비와 시스템이 유기적으로 구성되어 있으며, 이들의 효율적인 운영을 통해 생산성을 향상시킬 수 있다. 터미널의 안벽과 장치장 사이의 컨테이너 운송을 담당하는 이송장비는 컨테이너터미널의 핵심장비로 이의 효율적인 운영은 컨테이너터미널의 생산성과 직결되어 있다. 본 연구에서는 자동화 컨테이너터미널의 운영생산성 향상을 위한 하역장비와 이송장비의 운영방안에 대하여 연구한다. 특히 DHST(Dual Hoist Second Trolley)타입의 QC와 ASHC의 장비특성과 장비간의 연계작업을 고려하여, QC의 대기시간을 최소화하여 하역 생산성을 최대화할 수 있는 ASHC Dispatching Rule을 제시하고자 한다.