• Journal of Korean Society of Transportation
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• v.24 no.3 s.89
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• pp.167-176
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• 2006

An minimum path algorithm for integrated networks with departure time constraints require considering arrival time of arriving mode, transfer time. waiting time, and departure time of next mode. Integrated network with diverse modes commonly include departure time constraints. Because public mode suck as train and airplane have fixed service schedule which provide passengers. This study developed the k-path algorithm in integrated network with time varying conditions and departure time constraints. We proposed the extended method based on entire path deletion method, and examined the application of the proposed algorithm through case study.

• Journal of the Korea Convergence Society
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• v.9 no.5
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• pp.7-14
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• 2018

The purpose of this study is to analyze the effect of commuter's departure time on transportation system in future traffic system operated autonomous vehicle using agent based model. Various scenarios have been set up, such as when all passenger choose a similar departure time, or if the passenger chooses a different departure time. Also, this study tried to analyze the effect of road capacity. It was found that although many of the scenarios had been completed in a stable manner, many commuters were significantly coordinated at the desired departure time. In particular, in the case of a reduction in road capacity or in certain scenarios, it has been shown that, despite excessive schedule adjustments, many passengers are unable to commute before 9 o'clock. As a result, it is suggested that traffic management and pricing policies are different from current ones in the era of autonomous car operation.

• Journal of Korean Society of Transportation
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• v.18 no.6
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• pp.111-124
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• 2000

본 연구에서 다루고자 하는 문제는 서비스시간 제약을 갖는 도시부 복합교통망에서의 기종점을 잇는 합리적인 최단경로를 탐색하고자 하는 것이다. 서비스시간 제약은 도시부 복합교통망에서의 현실성을 보다 더 사실적으로 표현하지만 기존의 알고리즘들은 이를 고려하지 않고 있다. 서비스시간 제약은 환승역에서 여행자가 환승차량을 이용해서 다른 지점으로 여행할 수 있는 출발시간이 미리 계획된 차량운행시간들에 의해 제한되어지는 것이다. 환승역에 도착한 여행자는 환승차량의 정해진 운행시간에서만 환승차량을 이용해서 다른 지점으로 여행할 수 있다. 따라서 서비스시간 제약이 고려되어지는 경우 총소요시간에는 여행시간과 환승대기시간이 포함되어지고, 환승대기시간은 여행자가 환승역에 도착한 시간과 환승차량의 출발이 허용되어지는 시간에 의존해서 변한다. 본 논문에서는 이러한 문제를 해결할 수 있는 링크기반의 최단경로탐색 알고리즘을 개발하였다. Dijkstra 알고리즘과 같은 전통적인 탐색법에서는 각 노드까지의 최단도착시간을 계산하여 각 노드에 표지로 설정하지만 제안된 알고리즘에서는 각 링크가지의 최단도착시간과 각 링크에서의 가장 빠른 출발시간을 계산하여 각 링크의 표지로 설정한다. 제안된 알고리즘의 자세한 탐색과정이 간단한 복합교통망에 대하여 예시되어진다.

• Journal of Korean Society of Transportation
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• v.27 no.1
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• pp.143-155
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• 2009

A dynamic traffic assignment (DTA) has recently been implemented in many practical projects. The core of dynamic model is the inclusion of time scale. If excluding the time dimension from a DTA model, the framework of a DTA model is similar to that of static model. Similar to static model, with given exogenous travel demand, a DTA model loads vehicles on the network and finds an optimal solution satisfying a pre-defined route choice rule. In most DTA models, the departure pattern of given travel demand is predefined and assumed as a fixed pattern, although the departure pattern of driver is changeable depending on a network traffic condition. Especially, for morning peak commute where most drivers have their preferred arrival time, the departure time, therefore, should be modeled as an endogenous variable. In this paper, the authors point out some shortcomings of current DTA model and propose an alternative approach which could overcome the shortcomings of current DTA model. The authors substitute a traditional definition for time-dependent OD table by a new definition in which the time-dependent OD table is defined as arrival time-based one. In addition, the authors develop a new DTA model which is capable of finding an equilibrium departure pattern without the use of schedule delay functions. Three types of objective function for a new DTA framework are proposed, and the solution algorithms for the three objective functions are also explained.

• Journal of Korean Society of Transportation
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• v.19 no.5
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• pp.119-134
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• 2001

This paper proposed a dynamic transit vehicle simulation model and a dynamic transit passengers simulation model, which can simultaneously simulate the transit vehicles and passengers traveling on a transit network, and also developed an algorithm of dynamic departure time choice model based on individual passenger. The proposed model assumes that each passenger's behavior is heterogeneous based on stochastic process by relaxing the assumption of homogeneity among passengers and travelers have imperfect information and bounded rationality to more actually represent and to simulate each passenger's behavior. The proposed model integrated a inference and preference reforming procedure into the learning and decision making process in order to describe and to analyze the departure time choices of transit passengers. To analyze and evaluate the model an example transit line heading for work place was used. Numerical results indicated that in the model based on heterogeneous passengers the travelers' preference influenced more seriously on the departure time choice behavior, while in the model based on homogeneous passengers it does not. The results based on homogeneous passengers seemed to be unrealistic in the view of rational behavior. These results imply that the aggregated travel demand models such as the traditional network assignment models based on user equilibrium, assuming perfect information on the network, homogeneity and rationality, might be different from the real dynamic travel demand patterns occurred on actual network.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.157-168
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• 2006

Spatial detection system such as AVI, GPS, and Beacon etc. can provide spatial travel time only after a vehicle Passes through a road section. In this context, majority of the existing studies on the link travel time estimation area has focused on the arrival time-based link travel time estimation. rather than departure time-based link travel time estimation. Even if some of the researches on this area have developed departure time-based link travel time estimation algorithms, they are limited in that they are not applicable in a real-time mode. The objective of this study is to develop an departure time-based link travel time estimation algorithm which is applicable in a real-tine mode. Firstly, this study discussed the tradeoff between accuracy and timeliness of the departure time-based on-line link travel time estimates. Secondly, this study developed an departure time-based on-line link travel time estimation algorithm which utilizes the Baysian inference logic. It was found that the proposed approach could estimate departure time-based link travel times in a real-time context with an acceptable accuracy and timeliness.

• Journal of the Korea Society of Computer and Information
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• v.7 no.4
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• pp.174-181
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• 2002

In this Paper, we proposed the method for the TIT (Theoretical Inter-arrival Time) was suggested in which it saves the cells by using the data buffer in the system rather than by using one separately from the internal controller, and it also releases these cells saved. The method of TIT complements the defect of the accumulation of the delay in the method of RDT which considers the time of the cell that is discharged from the established cell interval controller. And, in order to apply the merit of RDT, the method of TIT sets its standards on the cells arrival time as it was in the method of RAT.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.21-32
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• 2007

The linear traffic model(Vertical queueing model) that is adopted widely in traffic flow estimation assumes that all vehicles have the identical motion before joining a queue at the stop-line. Thus, a queue is supposed to form vertically not horizontally. Due to the simplicity of this model, the departure time of the leading vehicle is assumed to coincide with the start of effective green time. Thus, the delay estimates given by the Vertical queueing model is not always realistic. This paper explores a microscopic traffic model(a Kinematic Car-following model at Signalised intersections: a KCS traffic model) based on the one dimensional Kinematic equations in physics. A comparative evaluation in delay and sensitivity of delay difference between the KCS traffic model and the previously known Vertical queueing model is presented. The results show that the delay estimate in the Vertical queueing model is always greater than or equal to the KCS traffic model; however, the sensitivity of delay in the KCS traffic model is greater than the Vertical queueing model.

• Journal of Korean Society of Transportation
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• v.24 no.6 s.92
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• pp.89-102
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• 2006

The purpose of this paper is to develop a dynamic OD estimating model to overcome the limitation of depicting teal situations in dynamic simulation models based on static OD trip. To estimate dynamic OD matrix we used the hybrid discrete choice model(called the 'Demand Simulation Model'), which combines travel departure time with travel mode and travel path. Using this Demand Simulation Model, we deduced that the traveler chooses the departure time and mode simultaneously, and then choose his/her travel path over the given situation In this paper. we developed a hybrid simulation model by joining a demand simulation model and the supply simulation model (called LiCROSIM-P) which was Previously developed. We simulated the hybrid simulation model for dependent/independent networks which have two origins and one destination. The simulation results showed that AGtt(Average gap expected travel time and simulated travel time) did not converge, but average schedule delay gap converged to a stable state in transportation network consisted of multiple origins and destinations, multiple paths, freeways and some intersections controlled by signal. We present that the hybrid simulation model can estimate dynamic OD and analyze the effectiveness by changing the attributes or the traveler and networks. Thus, the hybrid simulation model can analyze the effectiveness that reflects changing departure times, travel modes and travel paths by demand management Policy, changing network facilities, traffic information supplies. and so on.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.638-642
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• 2016

현재 양력발생의 원리는 긴 경로 이론과 동시 통과 이론 등으로 알려져 있으며, 이 이론들은 간단히 설명하려는 목적으로 인해 양력발생의 원리가 와전되어왔다. 본 연구에서는 여러 양력발생의 원리 중 Kutta-Joukowski의 이론을 이용하여 순환을 통한 양력발생의 관계에 대해 연구를 수행하였다. 해석 모델은 대칭형 에어포일인 NACA0012를 이용하였다. 해석 프로그램으로는 EDISON을 이용하였으며 시간에 따른 와도를 확인하기 위해 비정상상태 해석을 진행하였다. 그 결과 유동이 시간의 경과에 따라 에어포일 뒷전으로 밀려나면서 Kutta-Joukowski의 이론에 중요한 논점인 출발 와류가 생성됨을 확인할 수 있었다. 이로 인해 순환이 형성되어 양력이 발생함을 추측할 수 있다. 추가적으로 받음각과 출발 와류 사이의 영향성을 연구하였다. 받음각이 커짐에 따라 출발 와류가 에어포일 뒷전에서 더 크게 발생하였고, 받음각이 낮아질수록 출발 와류의 진행이 가속화됨을 확인할 수 있었다.