• 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)

• 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.

• 한국경영과학회지
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• 제26권1호
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• pp.97-108
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• 2001

Design and evaluation of AGV-based material handling systems are very complicated due to the randomness and the large number of variables involved Vehicle travel time is a key parameter for designing and evaluating AGV systems. Although loaded travel time is relatively easy to estimate, determination of empty vehicle travel time is difficult due to the inherent randomness of material handling systems. Most previous studies assume that the empty vehicle travel time is the same as the loaded travel time or assume very specific environments. This paper presents new vehicle travel time models for AGV-based material transport systems. The research effort is focused on the estimation of empty vehicle travel time under various vehicle dispatching policies. Simulation experiments are used to verify the proposed travel time models.

• 한국국방경영분석학회지
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• 제17권2호
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• pp.90-99
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• 1991

In this paper a dispatching rule, $D^{*}$, for AGV operations in automated manufacturing system is proposed to improve the performance measures. And the algorithm is compared with existing heuristic rules via simulation to evaluate its capabilities. It is shown that the proposed rule enhances mean flow time, makespan and throughput, and avoids the locking phenominon which can be fatal to the operation of automated manufacturing systems.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2002년도 추계공동학술대회논문집
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• pp.63-70
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• 2002

중심(Hub)항만이 피기 위한 주요과제는 자동화이다. 선진항만은 이미 자동화 컨테이너터미널을 실용화하고 있는 단계이고, 국내의 경우는 자동화 컨테이너터미널을 구축하기 위한 기본계획 및 실시설계가 되고 있는 실정이다. 자동화 컨테이너터미널의 핵심은 자동화 장비인 ATC(Automated Transfer Crane)와 AGV(Automated Guided Vehicle)의 효율적인 운영이다. 자동화 장비의 효율적인 운영은 자동화 컨테이너터미널의 생산성을 결정짓는 가장 중요한 요소이다. 본 논문에서는 자동화 컨테이너터미널에 효율적인 3가지의 An 운영규칙과 AGV 배정규칙을 사용하여 자동화 컨테이너터미널에서 컨테이너 선적시간을 최소로 할 수 있는 가장 적합한 장비운영규칙을 제안하고자 한다. 자동화 컨테이너터미널에서 자동화 장비 운영에는 예기치 않은 교착이나 간섭이 발생하므로, 장비운영에 관한 계획은 이벤트 중심으로 실시간으로 이루어져야 한다. 그래서 본 논문에서는 실시간 계획에 가장 적합한 An 운영규칙과 AGV 배정규칙을 제안하고, 이들 규칙들의 수행도를 평가하기 위해 실제 자동화 컨테이너터미널에서 생길 수 있는 다양한 환경들에서 시뮬레이션 한다. 이 시뮬레이션을 통해 다양한 파라미터-야드의 리마샬링(re-marshaling)정도, 컨테이너 처리 개수, 운영 AGV 대수-에서 가장 로버스터(robust)한 자동화 장비의 통합운영규칙을 제시한다.

• 한국시뮬레이션학회논문지
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• 제6권1호
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• pp.41-52
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• 1997

It is essential to construct an efficient material flow system for the successful introduction of automated manufacturing systems. Automated Guided Vehicle System (AGVS) plays a significant role more and more in modern manufacturing environments, because of the flexibility and the precision they offer. However, as the size and the complexity of systems increase, the problems of dispatching, routing and scheduling of AGVs become complicated due to their independent and asynchronous demands. In this paper, we review relevant papers, and provide a new and more efficient method for dispatching AGV, named MEVTT (Minimum Empty Vehicle Travel Time) and demonstrate its performance and efficiency using simulation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.82-87
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• 1993

A supervisory controller design technique for multiple-AGV systems is presented in this paper. The guidepath is represented in the form of a network, and its modifications are easily tested. The network has two-layered structure, where the path sets between each two nodes are made in advance using the K-shortest path algorithm. Occupation times for all links are stored in link-occupation table, and are updated after the dispatching time. Dispatching and scheduling for each AGV are optimized in terms of minimum-time objectives. In all times, the paths are guaranteed to be conflict-free and deadlock-free. The simplicity and flexibility on this control scheme make the supervisory suitable for real applications.

• 한국산업융합학회 논문집
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• 제12권1호
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• pp.19-25
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• 2009

We suggest and evaluate a dynamic scheduling rule of machines and material handling systems for on-line operation in job shop type Flexible Manufacturing System. Alternating status should be able to take operation scheduling procedures and without delay in dynamic industrial environments effectively. The interaction(SPT-NS, SPT-QSNS, SPT-NUJ, EDD-NS, EDD-QSNS, EDD-NUJ, CR-NS, CR-QSNS, CR-NUJ) between machine operation scheduling and AGV dispatching rule were also studied in this research. The performance evaluation which was obtained from DSS compares the performance of Flow time, and Empty to loaded travel ratio. It is Compared with the best rules & two system.

• 산업경영시스템학회지
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• 제23권54호
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• pp.87-95
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• 2000

To constuct the stochastic model for performance evaluation of Multi-AGV, two aspects must be considered. The first is stochastic situation for moving jobs. The second is the dispatching rule of AGV. In this paper, the stochastic model for performance evaluation of Multi-AGV is developed. The case of stochastic model with two AGV is developed. But it difficult to solve in the case of stochastic model with more than three AGV because the model have three-ordered equations. The evaluation factor of the model is utilization and empty travel time of AGV. Using these factors, one can easily evaluate a wide range of handling and layout alternatives from given flow data. Hence, the model would be most effective when used in the early stage of designing to narrow down the number of alternative prior to simuation.

• 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.