• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.97-109
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• 2014

Personal rapid transit (PRT) is a new transportation system, which is energy efficient and brings high quality of customer service. Customers arrive dynamically at stations and request transportation service. In this paper, we propose a new online PRT dispatching algorithm for pickup and delivery of customers. We adopt the nearest neighbor dispatching rule, which is known as performing well in general. We extend the rule with bipartite matching in order to deal with multiple vehicles and customers at the same time. We suggest a systematic way for selecting vehicles that will be considered to be dispatched, since the scope with which vehicles are selected may affect the system performance. We regard the empty travel distance of vehicles and the customer waiting time as the performance measures. By using simulation experiments, it has been examined that the scope of dispatching affects the system performance. The proposed algorithm has been validated by comparing with other dispatching rules for transportation services. We have shown that our algorithm is more suitable for PRT operating environment than other dispatching rules.

• 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.

• Journal of Navigation and Port Research
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• v.32 no.10
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• pp.829-835
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• 2008

The objective of this study is to present the two-step dispatching strategy for the purpose of the transport vehicle with multi-function used in container terminal. The two-step dispatching is a method to save the waiting time between transport vehicle and cranes using real time location control. The first step dispatching is to allocate the destination location based on the real time location information. The second step dispatching is to indicate the specific job such as loading, unloading, and pick-up based on the condition of working area. This two-step dispatching strategy decreases the waiting times of the stevedoring system and will contribute at a productivity improvement in container terminal.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.218-219
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• 2011

This paper focuses on dispatching strategy for AGVs(Automated Guided Vehicle). The goal of AGV dispatching problem is allocating jobs to AGVs to minimizing QC delay and AGV total travel distance. Due to the highly dynamic nature of container terminal environment, the effect of dispatching is hard to predict thus it leads to frequent modification of dispatching results. Given this situation, single rule-based approach is widely used due to its simplicity and small computational cost. However, single rule-based approach has a limitation that cannot guarantee a satisfactory performance for the various performance measures. In this paper, dispatching strategy based on multicriteria heuristics is proposed. Proposed strategy consists of multiple decision criteria. A muti-objective evolutionary algorithm is applied to optimize weights of those criteria. The result of simulation experiment shows that the proposed approach outperforms single rule-based dispatching approaches.

• Journal of Navigation and Port Research
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• v.35 no.6
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• pp.501-507
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• 2011

This paper focuses on dispatching strategy for AGVs(Automated Guided Vehicle). The goal of AGV dispatching is assigning AGVs to requested job to minimizing the delay of QCs and the travel distance of AGVs. Due to the high dynamic nature of container terminal environment, the effect of dispatching is hard to predict thus it leads to frequent modification of dispatching decisions. In this situation, approaches based on a single rule are widely used due to its simplicity and small computational cost. However, these approaches have a limitation that cannot guarantee a satisfactory performance for the various performance measures. In this paper, dispatching strategy based on multicriteria heuristics is proposed. The Proposed strategy consists of multiple decision criteria. A multi-objective evolutionary algorithm is applied to optimize weights of those criteria. The result of simulation experiment shows that the proposed approach outperforms single rule-based dispatching approaches.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1098-1101
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• 2013

물류업계는 배차 운송하기 위한 많은 알고리즘, 차량경로문제, 차량일정계획, GIS, GPS 등의 여러 연구를 진행하고 있다. 하지만 물류시장에 배송물량은 늘어나지만 배송을 하기 위한 차량과 기사는 한정되어 있으며 다단계 거래구조로 인해 수수료가 발생하여 최말단에 있는 화물차주만 수익이 감소한다. 이런 문제에 의해 차량주인(차주)는 운송장소와 운송비에 중점을 두고 배송 건을 선택하여 운송을 하고 있다. 본 논문에서는 이러한 물류기업의 배차문제와 차주 운임비 문제 해결을 위하여 운송비 기반배차 시스템의 정보화를 실현하기 위한 기초적인 데이터 구조를 제안하고, 운송비 중심의 배차 알고리즘이 적용된 배차 시스템을 물류업체에 적용한 결과를 제시하였다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.2
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• pp.1-13
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• 2009

Although enormous data have been collected in major cities (Korea) by APTS(Advanced Public Transit Systems), most of studies related to bus schedule management evaluation have confined to headway adherence and on-time performance. Therefore, bus operation management have been very lack of using APTS data. This study uses coefficient of correlation to evaluate bus company's schedule management level. However, direct application of coefficient of correlation has inequitable problem because of many limitation(number of vehicle, headway, etc). and so variable calibration method was developed and applied to cope with these problems. Thus, demand-elastic management evaluation index was developed. For verifying the equity of developed index, it is applied to Seoul bus routes. It is expected for the developed index to contribute into the demand-elastic management of bus schedule.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.319-322
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• 2014

Due to the active use of the internet currently, the transportation volume of logistics firms is dramatically increasing, but it is not easy to secure available vehicles and vehicle suppliers, so it is the most important for logistics companies to streamline transportations management and process. For such reason, there have been a number of studies to deal with VRP and VSP for efficient vehicle allocation planning of vehicle suppliers and vehicles. But it is hard to reflect traffic situations changing everyday and detailed geographic conditions, and it requires big scale of database and huge calculation time consumption as increase number of depots, which is very inefficient. For solving the vehicle allocation planning problems of 3PL firms with various constraints due to the transportation cost, this paper suggest new vehicle allocation information system and an algorithm based transportation cost/income. Also this paper presents actual results applied to a logistics company. As a result, the transportation profit of vehicle suppliers increased by 11 percent in average, when the developed transportation cost-based vehicle allocation system applied.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.385-386
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• 2022

Currently, global developed countries in shipping and logistics establish smart ports by introducing various digital technologies such as automated terminals and sharing platforms. This means that the importance of efficiency throughout the port by improving resource utilization efficiency and minimizing work idle time is increasing. Therefore, this study proposes a yard truck dispatching method of improving resource utilization efficiency. And we analyze the problems of the existing dispatching rules and develop Y/T dispatching algorithm that comprehensively considers related constraints. In addition, the simulation takes into account the terminal congestion based on the operation data of the Busan New Port, it is conducted using the existing dispatch method and developed Y/T dispatching algorithm. And the operational effects of analysis result are evaluated.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2007.11a
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• pp.564-569
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• 2007

자동화 컨테이너 터미널에서 안벽크레인, AGV(Automated Guided Vehicle)와 같은 하역장비의 작업은 수 많은 요인에 영향을 받으며, 이로 인해 각 장비의 작업시간을 정확하게 추정하는 것은 거의 불가능하다. 작업시간의 불확실성은 AGV 배차를 어렵게 만들고 작업효율을 떨어뜨리는 주요 원인이다. 본 논문에서는 이러한 불확실성에 대처하기 위하여 확률적 시뮬레이션 기반 AGV 배차 알고리즘을 제안한다. 제안 방안은 AGV를 배차할 때, 이후 일정 기간 동안의 AGV작업에 대해 확률적 시뮬레이션을 여러번 반복하여 수행하고 평가 값을 평균함으로써 불확실성의 영향을 줄인다. 확률적 시뮬레이션을 위해 크레인 작업시간의 불확실성을 간단한 확률함수로 모델링하고 그에 따라 크레인 작업시간을 결정한다. 또한 AGV 작업시간을 가감속, 간섭을 고려하여 추정한다. 시뮬레이션 실험을 통해 제안방안을 검증한 결과 안벽크레인의 지연이 감소함을 확인하였다.