• 대한교통학회지
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• 제25권3호
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• pp.137-144
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• 2007

대중교통 시스템의 운행계획 수립과정에서 배차간격은 중요한 결정 파라미터이다. 일반적으로 통행수요가 많은 첨두시간대에는 배차간격이 짧고 통행수요가 적은 비첨두시간에는 배차간격이 길다. 이는 시간대에 따라 변화하는 통행수요를 충족시키기 위해 요구되는 적정한 운행서비스를 공급하기 위함인데 수요의 탄력성이 없을 경우 이용자의 대기시간을 최소화하는 것과 일맥상통한다. 본 연구에서는 최적 배차계획표를 작성하는 문제를 해석적으로 풀이하였다. 배차간격은 단위 거리당 운행비용에 비례하고 통행수요와 대기시간계수에 반비례한다. 최적 배차간격은 통행수요의 양에 의해 결정되고. 각 배차시각은 수요의 분포함수에 의해 결정되는 것을 확인하였다. 따라서 통행수요가 많은 첨두시간대에는 배차간격이 짧고 수요가 많지 않은 비첨두시간대에는 배차간격이 길어지게 되어 일반적인 상식을 뒷받침해주는 이론적 근거가 된다. 기존의 해석적 연구에서는 전체 서비스시간 또는 분할된 서비스시간대의 길이를 균등하게 분할한 각 시각에 차량을 배차할 것을 제시하였는데, 본 연구의 결과를 통해 해석할 경우 이는 분석 시간대 동아의 통행수요가 균일할 경우, 즉 수요가 균일분포를 따를 경우에 국한된 것이라 하겠다. 따라서 본 연구는 기존의 해석적 연구를 확장시킨 일반화된 연구라 하겠다. 본 연구에서는 어렵지 않은 계산을 통해 간단하게 배차계획표를 작성하는 방법을 제공한 것에 큰 의미를 갖는다. 또한 본 연구를 일반적으로 해석할 경우 모든 간격 설정 문제에 적용될 수 있고 간격변수를 시간에서 공간으로 변경할 경우 정류장의 간격, 도로의 간격 노선의 간격 등의 모든 시설물의 간격을 결정하는 문제에서도 적용될 수 있는 확장성을 갖는다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2000년도 춘계공동학술대회 논문집
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• pp.151-151
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• 2000

• Industrial Engineering and Management Systems
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• 제6권2호
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• pp.125-135
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• 2007

An automated guided vehicle (AGV) system is a group of collaborating unmanned vehicles which is commonly used for transporting materials within manufacturing, warehousing, or distribution systems. The performance of an AGV system depends on the dispatching rules used to assign vehicles to pickup requests, the vehicle routing protocols, and the home location of idle vehicles, which are called dwell points. In manufacturing and distribution environments which emphasize just-in-time principles, performance measures for material handling are based on response times for pickup requests and equipment utilization. In an AGV system, the response time for a pickup request is the time that it takes for the vehicle to travel from its dwell point to the pickup station. In this article, an exact dynamic programming algorithm for selecting dwell points in a tandem-loop multiple-vehicle AGV system is presented. The objective of the model is to minimize the maximum response time for all pickup requests in a given shift. The recursive algorithm considers time restrictions on the availability of vehicles during the shift.

• 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)

• 대한교통학회지
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• 제13권1호
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• pp.83-94
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• 1995

Many taxis called "Mobum" in Seoul are empty and waiting along the curb during the day time. However, it is almost impossible for elderly and handicapped people, and women carrying babies to use them .It is because they can not serve passengers who request services by phone. If taxis, expecially "Mobum" taxis which offer high quality services, can be dispatched based on requests by phone, not only elderly and handicapped people but also auto commuters will easily call and use them. This paper shows a taxi dispatching system. The system minimizes the total empty vehicle hours under given number of empty vehicles and passengers and their locations. As a result, the system maximizes number of services and revenue under given number of taxis. The system adopts a well -known linear programming model and the model can fast and easily be solved by PC level linear programming packages. Also, practical solutions of the system's constraints such as size and travel time forecast are discussed.ecast are discussed.

• Industrial Engineering and Management Systems
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• 제9권2호
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• pp.178-194
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• 2010

To improve the ship operation in automated container terminals, it is important to schedule different types of handling equipment to operate synchronously. For example, a vehicle with container receiving and lifting capabilities is used to transport containers from a storage yard to a vessel and vice versa, while a triple quay crane (QC) can handle up to three 40-ft containers simultaneously. This paper discusses the manner in which vehicles should be assigned to containers to support such multi-lifts of QCs by using information about the locations and times of deliveries. A mixed-integer programming model is introduced to optimally assign delivery tasks to vehicles. This model considers the constraint imposed by the limited buffer space under each QC. A procedure for converting buffer-space constraints into time window constraints and a heuristic algorithmfor overcoming the excessive computational time required for solving the mathematical model are suggested. A numerical experiment is conducted to compare the objective values and computational times of the heuristic algorithm with those of the optimizing method to evaluate the performance of the heuristic algorithm.

• 산업공학
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• 제11권1호
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• pp.119-129
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• 1998

The relative importance of Logistics in steelworks industry is rather higher among other business activities. The objective of the paper is to propose the methodology for real-time vehicle scheduling for scrap disposal in the steelworks industry. Currently, the rule necessary to assign vehicles to a specific job is strictly fixed. The paper adopts the multi-pass rule selector (MPRS) that suggests a promising rule used for vehicle dispatching for a period of time. The MPRS is regularly invoked if necessary and then evaluates a set of rule candidates to select the best rule with respect to the system performance criteria. The experiment shows that the proposed approach outperforms the current single-pass strategy.

• 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.

• 산업경영시스템학회지
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• 제23권58호
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• pp.29-39
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• 2000

This paper concerns the location of the transit point between adjacent loops and guide direction of loops in the tandem configuration manufacturing system. The tandem configuration has been used to solve control problems like the vehicle dispatching and traffic control. The transit point between loops needs to deliver the parts from one loop to another. The location of transit point between adjacent loops and direction of loops must be determined to minimize the total travel time of parts in the manufacturing system. The model formulation is developed, a numerical example is shown.

• 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.