• Journal of Korean Society of Transportation
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• v.20 no.5
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• pp.153-161
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• 2002

다사용자계층 통행배정(Multiple User Class Assignment) 문제란 교통망을 이용하는 통행자들이 이질적인 통행계층으로 구성된 경우, 이들 각 계층의 통행수요를 교통망에 배정하는 문제를 의미한다. 이는 기존 통행 배정모형들이 모든 통행자의 통행특성이 동질적이라고 가정함으로서 발생하는 불합리한 통행배정 결과를 완화시키기 위한 방법이다. 또한, 최근 지능형교통체계(Intelligent Transportation Systems, ITS)사업에서 교통정보제공시스템이 구현될 예정임에 따라, 교통정보를 제공받는 계층과 그렇지 못한 계층간의 영향을 분석하거나 혼잡통행료부과 등과 같은 교통관리전략을 정확히 평가하기 위해서 다사용자계층 통행배정모형에 대한 관심이 증가하고 있다. 그러나, 다사용자계층 통행배정모형의 경우, 사용자간의 상호영향으로 통행비용함수의 1차 편미분행렬(Jacobian matrix)이 비대칭(Asymmetric)이 되어 동등 수리최소화문제(Equivalency mathematical Minimization program)로 구성할 수 없고 또한 수치적으로 풀기가 어렵다는 문제가 있다. 본 연구는 이런 문제점을 극복할 수 있는 모형식과 알고리듬을 제시코자 한다. 본 연구에서 제시된 모형은 2가지 특징이 있다. 먼저, 각 사용자 계층간의 상호영향을 모형내에 반영하며, 기종점쌍간의 통행시간변화에 따른 수요변화를 고려한다는 점이다. 이를 위하여 변동부등모형(Variational Inequality Model. VI)으로 문제를 구성하며, 이에 대한 해석 알고리듬도 제시한다. 또한, 변동부등모형으로 구축된 다사용자계층 모형이 다사용자계층 균형조건과 동일함을 보여주는 동등성조건(Equivalency condition)도 제시한다.

• Journal of Korean Society of Transportation
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• v.19 no.5
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• pp.61-70
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• 2001

The origin and destination(O-D) matrix is one of the most important elements in transportation planning process. Traditionally, transport planners survey the O-D movements in order to estimate the O-D matrix. Even though the cost of the O-D survey requires high amounts of resources, the accuracy is relatively low. Therefore, many researchers have studied the estimation of the O-D matrix for automobile from traffic counts. however, there is a little attention for the application on the transit O-D matrix estimation from traffic counts. The objective of this study is therefore the estimation of the transit O-D matrix from traffic counts using Gradient method. which is verified by the reliability analysis using a contrived small example network.

• Journal of Korean Society of Transportation
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• v.17 no.2
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• pp.137-147
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• 1999

This paper studies on the optimal bus network design in the framework of the set covering theory. The theory enables to cover passenger's loading and alighting areas as the set, and maximize the covering set as much as possible. In other words, it calculates the minimal set of the bus routes for covering whole bus passengers demand. After the optimal set of the bus routes is generated by the set covering theory, multimodal traffic equilibrium assignment is used for evaluating the generated set in terms of passenger's mode and route choice behavior. Whilst most previous works on it have been based on analyzing a specific route in a limited area, this study seeks to optimize the whole bus network.

• Journal of Korean Society of Transportation
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• v.19 no.3
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• pp.115-131
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• 2001

The Purpose of this study is to develop a simulation model for large-scale network with interrupted flow as well as uninterrupted flow. The Cell Transmission(CT) theory is used to simulate traffic flow. Flow transition rules have been newly developed to simulate traffic flows at merging and diverging sections, and signalized intersections. In the model, it is assumed that dynamic OD table is exogenously given. Simulation results for toy network shows that the model can explain queue dynamics not only in signalized intersections of urban arterials, but also in merging and diverging sections of freeway. In case study, the model successfully simulated traffic flows of 145,000 vehicles on CBD network of city of Seoul with 74 traffic zones, 133 signalized intersections among 395 nodes and 1110 links.

• Journal of Korean Society of Transportation
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• v.21 no.1
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• pp.53-63
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• 2003

The Origin-Destination(OD) matrix is very important in describing transport movements in a region. The OD matrix can be estimated using traffic counts on links in the transport network and other available information. This information on the travel is often contained in a target OD matrix and traffic counts in links. To estimate an OD matrix from traffic counts, they are the major input data which obviously affects the accuracy of the OD matrix estimated, Generally, the quality of an estimated OD matrix depends much on the reliability of the input data, and the number and locations of traffic counting points in the network. Any Process regarding the traffic counts such as the amount and their location has to be carefully studied. The objective of this study is to select of the optimal location of traffic counting points for the OD matrix estimation. The model was tested in nationwide network. The network consists of 224 zones, 3,125 nodes and 6,725 links except to inner city road links. The OD matrix applied for selection of traffic counting points was estimated to 3-constrained entropy maximizing model. The results of this study follow that : the selected alternative to the best optimal counting points of six alternatives is the alternative using common links of OD matrix and vehicle-km and traffic density(13.0% of 6,725 links), however the worst alternative is alternative of all available traffic counting points(44.9% of 6,725 links) in the network. Finally, it should be concluded that the accuracy of reproduced OD matrix using traffic counts related much to the number of traffic counting points and locations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.5
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• pp.13-25
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• 2008

This study analyzed errors of data received from GPS which showed different reception characteristics based on chipset at poor reception area. The digital map made from National Police Agency shows 4% errors of length on the average. The comparison of three different algorithms - Average Spot Speed, Cumulative Travel Length from GPS with Actual Travel Time, Travel Length from Digital Map with Actual Travel Time have been conducted to find significant difference estimating travel time from GPS Data. The algorithm to estimate travel time from travel length and travel time showed the most reliable results from the others.

• Proceedings of the KOR-KST Conference
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• 2007.11a
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• pp.219-228
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• 2007

기업의 물류활동은 화물의 기종점 정보와 더불어 출발지와 도착지간 수배송특성, 업종간 거래 관계, 가격흐름, 경로 등 다양한 공급사슬관점에서 설명되어야 한다. 본 연구는 화물의 흐름을 물적인 흐름의 공급사슬망인 유통경로 관점에서 실증분석을 목적으로 한다. 그동안 공공부문의 물류관련 연구들은 물류현황조사 자료로부터 지역간 기종점 통행량에 기초하여 물류시설을 포함한 국가의 사회간접자본 투자정책에 주로 활용된 경향이 있었다. 또한, 민간부문의 유통경로 관련 연구는 주로 상적인 유통경로에 한정되어 보다 종합적인 공급사슬관리 측면에서 기업의 물적 유통경로선택에 대한 이해가 부족하였다. 본 연구에서는 2001년 전국물류현황조사중 기업의 물류실태조사에서 수행된 600개의 표본자료에 기초하여 기업들의 유통경로 선택의 특성을 분석하였다. 사용된 자료들의 설문조사방식은 다양한 유통노드들이 제시되고, 기업들이 상위 매출액이 높은 품목들이 다양한 유통경로 상에서 어떻게 노드들을 이용하는지 조사되었고, 이를 공장순회형, 물류센터 중심형, 도매자 중심형, 소비자 중심형 등 4개로 유형화하였다. 본 연구는 이들 4개의 유통경로들의 선택에 미치는 영향을 사업체 현황, 수배송현황, 물류활동평가, 물류시설관리 현황 등의 다양한 특성변수를 고려하여 선택에 미치는 영향을 분석하였다.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.145-153
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• 2008

Existing shortest-path algorithms mainly consider a single attribute. But traveler actually chooses a route considering not single attribute but various attributes which are synthesized travel time, route length, personal preference, etc. Therefore, to search the optimal path, these attributes are considered synthetically. In this study route searching algorithm which selects the maximum utility route using discrete choice model has developed in order to consider various attributes. Six elements which affect route choice are chosen for the route choice model and parameters of the models are estimated using survey data. A multinomial logit models are developed to design the function of route choice model. As a result, the model which has route length, delay time, the number of turning as parameter is selected based on the significance test. We use existing shortest path algorithm, which can reflect urban transportation network such as u-turn or p-turn, and apply it to the real network.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.3
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• pp.33-41
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• 1982

Development is given for an analytical approach that can investigate parameters characterizing road network geometry. A grid transportation network having a hierarchy structure is considered on a homogeneous and isotropic urban plane in which trip origins and destinations are uniformly dispersed and the trip length distribution is independent of the location of the origin. The object is to find the optimal spacings between urban arterials so as to minimize the sum of travel and construction costs, subject to the hypothesis that a trip assignment follows the Wardrop's first principle. The proposed approach is not the genera method for determining an efficient network layout, but can be used as basic concept for generating and evaluating urban road network alternatives. Given an O-D table and cost estimates the approach is able to outline at least in a qualitative sense the optimal spacings of urban arterial roads.

• Journal of Korean Society of Transportation
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• v.33 no.2
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• pp.170-181
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• 2015

This study explores passengers' travel characteristics at six bus stops on the Seoul Ring Expressway using smart traffic card data. Based on the characteristics, political strategies to improve bus facilities on expressway are suggested. Firstly, among them two bus stops of Guri and Uiwang-Cheonggye have higher transfer rate of passengers, 37.56% and 36.9% of the total intercity (red) bus passengers on the expressway, respectively. Secondly, Uiwang-Cheonggye bus stop has the highest transfer rate, and Guri bus stop has also higher transfer rate and the highest on-and-off passengers. It implies that both bus stops need to be prioritized for improving bus stop facility, access roads, and connection facility between the bi-directional stops. Thirdly, Guri (down) bus stop has relatively longer waiting time for transfer, thus shorter bus headways running the bus stop should be considered. Lastly, most passengers using both stops come to and from Bundang-gu in Geongnam City. Overall, the results of this study would be helpful for transport planners to develop effective bus route policies and bus operation.