• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.193-206
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• 2002

A signal optimization model is proposed by applying the Cell-Transmission Model(CTM) as an embedded traffic flow model to estimate a system-optimal signal timing plan in a transportation network composed of signalized intersections. Beyond the existing signal-optimization models, the CTM provides appropriate theoretical and practical backgrounds to simulate oversaturation phenomena such as shockwave, queue length, and spillback. The model is formulated on the Mixed-Integer Programming(MIP) theory. The proposed model implies a system-optimal in a sense that traffic demand and signal system cooperate to minimize the traffic network cost: the demand departing from origins through route choice behavior until arriving at destinations and the signal system by calculating optimal signal timings considering the movement of these demand. The potential of model's practical application is demonstrated through a comparison study of two signal control strategies: optimal and fixed signal controls.

• Journal of the Korea Safety Management & Science
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• v.5 no.1
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• pp.13-31
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• 2003

This provided a basic frame to analyze the investment effect on the road, railroad, airport and port as a national dimension but it still has a limitation to analyze the specific economic and financial validities to consider the characteristics of the traffic facilities within the area. Conclusively, the aims of this study provide the reasonable evaluation guidelines effectively to the local automatic groups, especially Chungju in the frame of the present evaluation guidelines. We provide the adaptive alternatives on the present systems which are difficult to adapt to the present investment evaluation guidelines; the estimation method of the social economic index and the estimation method of the traffic demand. Additionally, we discuss the research method of the passage actual state for a reasonable estimation of the traffic demand. The result of this study will be activated for the validity check and construction plan of the reasonable traffic investment plan of Chungju city.

• Journal of Korean Society of Transportation
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• v.20 no.4
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• pp.135-150
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• 2002

The basic assumption of analytical Dynamic Traffic Assignment models is that traffic demand and network conditions are known as a priori and unchanging during the whole planning horizon. This assumption may not be realistic in the practical traffic situation because traffic demand and network conditions nay vary from time to time. The rolling horizon implementation recognizes a fact : The Prediction of origin-destination(OD) matrices and network conditions is usually more accurate in a short period of time, while further into the whole horizon there exists a substantial uncertainty. In the rolling horizon implementation, therefore, rather than assuming time-dependent OD matrices and network conditions are known at the beginning of the horizon, it is assumed that the deterministic information of OD and traffic conditions for a short period are possessed, whereas information beyond this short period will not be available until the time rolls forward. This paper introduces rolling horizon implementation to enable a multi-class analytical DTA model to respond operationally to dynamic variations of both traffic demand and network conditions. In the paper, implementation procedure is discussed in detail, and practical solutions for some raised issues of 1) unfinished trips and 2) rerouting strategy of these trips, are proposed. Computational examples and results are presented and analyzed.

• Journal of the Korean Operations Research and Management Science Society
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• v.26 no.4
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• pp.99-108
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• 2001

In the ring loading problem with demand splitting, traffic demands are given for each pall of nodes in an undirected ring network and a flow is routed in either of the two directions, clockwise and counter-clockwise. The load of a link is the sum of the flows routed through the link and the objective of the problem is to minimize the maximum load on the ring. The fastest a1gorithm to date is Myung, Kim and Tcha＇s a1gorithm that runs in Ο(n｜K｜) time where n is the number of nodes and K is the index set of the origin-destination pairs of nodes having flow traffic demands. Here we develop an a1gorithm for the ring loading problem with demand splitting that improves the rerouting step of Myung, Kim and Tcha＇s a1gorithm arid runs in Ο(min{n｜K｜, n$^2$}) time.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.61-70
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• 2010

The purpose of this study is to analyze the accuracy of traffic volume forecast by comparing an estimated to real traffic volume. For this study, total 10 sections of national highways, which are planned in 1980s and 1990s, were selected and traffic analysis data for highway construction were collected. In addition, targeted 10 sections were categorized into network-related and -unrelated sections. In the analysis of inaccuracy between the estimated and real traffic, for network-related sections, appeared to have lower inaccuracy. As time goes on after traffic open, inaccuracy between the estimated and real traffic appeared to be lower. In various section lengths, the longer the section length, the higher the inaccuracy is. Using 3 years passed data after traffic open, national highway have lower inaccuracy than expressway. However, the traffic analysis according to traffic open time resulted in little change of the inaccuracy.

• Journal of the Korean Society for Railway
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• v.17 no.2
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• pp.140-147
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• 2014

Line planning is an important step to determine the optimal frequencies of trains given the forecasted demand for each train type. The main input data for line planning is the leg traffic demand which can be derived using suitable traffic assignment models. However most assignment models require a line plan, in other words, train frequencies or headways, so that inconsistent results just by the procedural approach to find an optimal line plan after determining leg traffic can be avoided. This paper suggests a unified model that can consider the traffic assignment and line planning, simultaneously. We further provide an elaborated approximation algorithm and, finally, provide experimental results determined for the Korean railway network.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.48-56
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• 2002

This paper proposes an IP(Internet Protocol) multicast routing method by multiple tree routes. Multiple trees, instead of a single tree, improve the quality of multicast services with nonlinear link cost and huge traffic demand. The proposed method adds tree routes until it satisfies target conditions, and it splits the multicast traffic demand into the chosen tree routes. We develop a mathematical model and optimal conditions for traffic splitting. The method works on the problems with many different simultaneous multicast traffic. Various experiments were carried and the results show that the new multicasting is fairly effective on end-to-end quality of services.

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.52-61
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• 2018

This research suggested the traffic signal timing calculation model for signal intersections based on sectional travel time. A detection system that collects sectional travel time data such as Urban Transport Information System(UTIS) is applied. This research developed the model to calculate saturation flow rate and demand volume from travel time information using a deterministic delay model. Moreover, this model could determine the traffic signal timings to minimize a delay based on Webster model using traffic demand volume. In micro simulation analysis using VISSIM and its API ComInterface, it checked the saturation conditions and determined the traffic signal timings to minimize the intersection delay. Recently, sectional vehicle detection systems are being installed in various projects, such as Urban Transportation Information System(UTIS) and Advanced Transportation Management System(ATMS) in Korea. This research has important contribution to apply the traffic information system to traffic signal operation sector.

• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.107-116
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• 2010

The vehicle travel time between locations in a downtown is greatly influenced by both complex road conditions and traffic situation that changes real time according to various external variables. The customer's demands also stochastically change by time period. Most vehicle routing problems suggest a vehicle route considering travel distance, average vehicle speed, and deterministic demand; however, they do not consider the dynamic external environment, including items such as traffic conditions and stochastic demand. A realistic vehicle routing problem which considers traffic (smooth, delaying, and stagnating) and stochastic demands is suggested in this study. A mathematical programming model and hybrid genetic algorithm are suggested to minimize the total travel time. By comparing the results considering traffic and stochastic demands, the suggested algorithm gives a better solution than existing algorithms.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.3 no.2
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• pp.251-257
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• 2003

In this paper, we wish to construct a optimal traffic cycle using wire remote control. if police vehicle or ambulance suddenly enter the traffic Intersection, it will increase the traffic accident. In this paper, wireless traffic light use the radio traffic control signal and research about the hardware manufacture to check special detectors on urgency vehicles may safety and rapidly enter traffic intersection. Also, this paper present a traffic signal control conditions that analyzes different traffic intersection flows in cases of saturated flows, where the real traffic volume demand is large and the capacity constraints of bottlenecks have significant effects on the flow patterns. Through computer simulation this wireless traffic light has been proven to be much more safety and efficient than fixed traffic signal light which does not consider emergency vehicles for safety escort.