• Journal of the Korea Safety Management & Science
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• v.13 no.4
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• pp.125-137
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• 2011

Customers are generally requiring a variety of products, earlier due date, and lower price. A manufacturing process needs the efficient scheduling to meet those customer's requirements. This study proposes the novel algorithm named MJA(Minimum Job completion time and AGV time) that increases the performance of machines and AGV(Automated Guided Vehicles) in many kinds of job types. MJA optimizes the bottleneck of machines and efficiency of AGV with considering two types of dispatching at the same time. Suggested algorithm was compared with existing heuristic methods by several simulations, it performed better for reducing the time of tardiness.

• Journal of the Korea Society for Simulation
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• v.27 no.2
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• pp.71-81
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• 2018

Forklifts in a shipyard lift and transport heavy objects. Tasks occur dynamically and the rate of the task occurrence changes over time. Especially, the rate of the task occurrence is high immediately after morning and afternoon business hours. The weight of objects varies according to task characteristic, and a forklift also has the workable or allowable weight limit. In this study, we propose an online forklift dispatching algorithm based on nearest-neighbor dispatching rule using minimal cost assignment approach in order to attain the efficient operations. The proposed algorithm considers various types of forklift and multiple jobs at the same time to determine the dispatch plan. We generate dummy forklifts and dummy tasks to handle unbalance in the numbers of forklifts and tasks by taking their capacity limits and weights. In addition, a method of systematic forklift selection is also devised considering the condition of the forklift. The performance indicator is the total travel distance and the average task waiting time. We validate our approach against the priority rule-based method of the previous study by discrete-event simulation.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.2
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• pp.73-83
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• 2011

In the manufacturing system, production-planning is very important in effective management for expensive production facilities and machineries. To enhance efficiency of Manufacturing Execution System(MES), a manufacturing system that reduces the difference between planning and execution, certain production-planning needs a dispatching rule that is properly designed for characteristic of work information and there should be a appropriate selection for the rule as well. Therefore, in this paper dispatching rule will be selected by several simulations based on characteristics of work information derived from process planning data. By constructing information that are from simulation into ontology, one of the knowledge-based-reasoning, production planning platform based on the selection of dispatching rule will be demonstrated. The platform has strength in its wider usage that is not limited to where it is applied. To demonstrate the platform, RacerPro and Prot$\acute{e}$g$\acute{e}$ are used in parts of ontology reasoning, and JAVA and FlexChart were applied for production-planning simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2021-2029
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• 2010

This paper suggested the method to design and analyze FMC robot's dispatching rule using the Simulation and Sequential Patterns. To do this, first of all, we built FMC using simulation and then, extracted signals that facilities call a robot, saved it as the log type. Secondly, we built robot's optimal path using the Sequential Pattern Mining with the results of analyzing the log and relationship between machine and robot actions. Lastly, we adapted it to the A corp.'s manufacturing line for verifying its performance. As a result of applying the new dispatching rule in FMC, total throughput and total flow time decrease because of decreasing material loss time and increasing robot utility. Furthermore, because this method can be applied for every manufacturing plant using simulation, it can contribute to advance total FMC efficiency as well.

• IE interfaces
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• v.25 no.3
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• pp.357-364
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• 2012

This paper considers a unrelated parallel machine scheduling problem with ready times, due times and sequence and machine-dependent setup times. The objective of this problem is to determine the allocation of jobs and the scheduling of machines to minimize the total tardy time. A mathematical model for optimal solution is derived. An in-depth analysis of the model shows that it is very complicated and difficult to obtain optimal solutions as the problem size becomes large. Therefore, a genetic algorithm using an effective dispatching method is proposed. The performance of the proposed genetic algorithm is evaluated using several randomly generated examples.

• Journal of Korean Society of Transportation
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• v.25 no.3
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• pp.137-144
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• 2007

This study involves an analytical approach to determine transit dispatching schedules (headways) Determining a time schedule is an important process in transit system planning. In general, the transit headway should be shorter during the peak hour than at non-peak hours for demand-responsive service. It allows passengers to minimize their waiting time under inelastic, fixed demand conditions. The transit headway should be longer as operating costs increase, and shorter as demand and waiting time increase. Optimal headway depends on the amount of ridership. and each individual vehicle dispatching time depends on the distribution of the ridership. This study provides a theoretical foundation for the dispatching scheme consistent with common sense. Previous research suggested a dispatching scheme with even headway. However, according to this research, that is valid for a specific case when the demand pattern is uniform. This study is a general analysis expanding that previous research. This study suggests an easy method to set a time table without a complex and difficult calculation. Further. if the time axis is changed to the space axis instead, this study could be expanded to address the spacing problems of some facilities such as roads. stations, routes and others.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.353-359
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• 1993

본 연구에서는 객체지향 개념과 분산형 문제해결 방법의 장점을 혼합한 FMS 생산현장통제 시스템을 제안하였다. 제안된 시스템은 FMS의 모든 구성요소를 지능적인 객체로써 표현하고, 객체들간의 Bidding 과정을 통하여 생산 현장의 상태변화에 대응해 나가는 구조를 가지고 있다. 실험 결과, 제안된 시스템은 기존의 Dispatching rule에 비하여, job의 시스템내 체류시간이 감소하며 기계부하가 평준화되는 현상을 나타내었다.

• Journal of Korean Institute of Industrial Engineers
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• v.16 no.2
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• pp.23-36
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• 1990

A unit-load automated guided vehicle system is considered in which a single vehicle is operated on a unidirectional path in a closed loop. The vehicle serves a manufacturing cell moving pallets from one station to another based on the "First-Encountered-First-Serve" dispatching rule. An approximation method is developed to compute the mean waiting time of an arbitrary pallet at each station. Extensive numerical experiments, performed for various problems, yield fairly good results in most of the cases compared with those obtained by simulation method.

• IE interfaces
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• v.13 no.3
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• pp.455-461
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• 2000

Logistics systems can be evaluated by how productively distribution center operates, how promptly transportation vehicle dispatches, how efficiently facility layout is, and so on. In this paper, a practical vehicle routing scheme with fixed delivery time and fixed vehicle routes is introduced. The method helps the distribution center reduce logistics cost with respect to dispatching vehicles, and satisfy the customer with pre-determined delivery time window constraints. A case study has shown that the proposed scheme not only generates a feasible schedule with time windows, but also balances material flow in warehouse.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.67-69
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• 2000

분산 시스템은 원거리에 위치한 자원들을 하나의 시스템으로 통합하여 여러 가지 장점을 제공한다. 하지만 시스템의 규모가 커짐에 따라서 관리자 노드와 관리 대상 노드간의 빈번한 상호작용에 의해서 전체적인 시스템의 성능저하가 발생할 수 있다. 에이전트를 사용한 방법으로 중앙 집중형 관리 방법의 폴링(polling)에 따른 문제점을 해결하였으나 에이전트 사용에 있어서도 에이전트가 이동하는 파견방법에 따라서 성능의 차이가 발생할 수 있다. 즉, 에이전트를 파견하는 관리 대상 노드의 지역 계산 시간에 따라서 관리자 노드에서의 전체적인 응답시간과 네트워크의 부하가 달라질 수 있다. 따라서, 본 논문에서는 에이전트가 관리 대상 노드에서의 지역 계산 시간에 따라 현재 작업중인 노드의 다음 노드로 새로운 에이전트를 파견하여 관리자 노드에서의 응답시간과 네트워크 부하를 줄일 수 있는 방법을 제시하고 기존의 모델과의 평가를 응답시간과 네트워크 부하 측면에서 비교, 평가하였다.