• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.12-20
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• 2008

Recent wireless communication technologies are envisioned as an innovative alternative to solve transportation problems. On ad hoc networks, as a wireless communication technology, nodes can communicate data without any infrastructure. In particular, vehicular ad hoc networks (VANETs), a specific ad hoc network applied to vehicles, enable vehicles equipped with a communication device to form decentralized traffic information systems in which vehicles share traffic information they experienced. This study investigated traffic information dissemination in a VANET-based traffic information system. For this study, an integrated transportation and communications simulation framework was developed, and experiments were conducted with real highway networks and traffic demands. The results showed that it took 3 minutes in the low traffic density situations (10 vehicle/lane.km) and 43 seconds in the high traffic density condition (40 vehicle/lane.km) to deliver traffic information of 5km away with 10% market penetration rate. In uncongested traffic conditions, information seems to be disseminated via equipped vehicles in the opposite direction. In congested traffic conditions, the sufficient availability of equipped vehicles traveling in the same direction reduces the chance to use vehicles in the opposing direction even though it is still possible.

• Journal of Korean Society of Transportation
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• v.19 no.2
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• pp.53-60
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• 2001

본 논문의 목적은 대중교통 노선배정 시에 여러 수단간의 환승을 고려함으로써 다수단 대중교통망 내에서 수단선택과 노선선택을 동시에 수행할 수 있도록 확률적인 통행배분(traffic assignment) 모형의 하나인 다이알 알고리즘을 응용할 것을 제시하고 그 알고리즘의 속성을 정확하게 규명하는데 있다 승용차의 확률적 통행배분모형으로 잘 알려져 있는 Dial 알고리즘은 로짓모형에 기초한 것이므로 다수단간의 대중교통 수단선택과 노선선택과 같은 선택 행태를 동시에 설명할 수 있는 모형적 특성을 기본적으로 내재하고 있다. 본 연구에서 제시한 대중교통 노선선택에 적용될 수 있도록 수정된 다이알 알고리즘은 기존의 결정적 대중교 통 노선배정 모형들의 단점을 극복할 수 있는 특성을 갖고 있다. 즉 결정적 대중교통 노선배정모형은 기종점간 최단경로에 교통량을 전랑배분(All-or-Nothing)하여 통행자들의 행태적 속성을 제대로 반영하지 못하고 있으며, 다수단 대중교통망 내에서 환승을 포함한 복합 대중교통수단의 선택을 효용극대화 이론에 기초하지 않고 최소비용노선에 전량배분하는 모형의 한계점을 갖고 있다. 이러한 결정적 대중교통 노선배정모형의 단점을 수정된 다이알 알고리즘은 개선할 수가 있다. 본 연구에서는 알고리즘의 특성을 파악하기 위한 모의실험으로 Sioux Falls 형태의 대중교통 네트워크를 이용하여 기존의 알고리즘과 비교 분석하였다. 분석의 탄력성을 갖고 있는 수정된 대중교통 다이알 알고리즘이 현실적 대중교통 통행패턴을 기존 모형보다 합리적으로 설명할 수 있을 것으로 보이며, 특히 다수단 대중교통망이 형성된 대도시의 대중교통 정책분석에 적합한 기법이 될 수 있을 것으로 고려된다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.1
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• pp.132-145
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• 2021

This study analyzes the main road network for road users to manage roads efficiently and derives problematic road sections to be improved. Traditional road management has been operated by manager-oriented view and a diversified road management system based on congestion. Therefore, in this research, the mail road Network was selected from the viewpoint of passenger-oriented, logistics-oriented and tourism-oriented, and the problematic road sections were derived through Level Of Service (LOS) analysis, safety analysis using EPDO accident rate, and network service analysis. This study emphasizes the efficient user-oriented road construction and management system and the need of constructing a mail road network, and it suggests the improvement strategies.

• Journal of Korean Society of Transportation
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• v.26 no.5
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• pp.175-184
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• 2008

Uncertainties are unavoidable in engineering applications. In this paper we propose an alpha reliable multi-variable network design problem under demand uncertainty. In order to decide the optimal capacity enhancement, three performance measures based on 3E(Efficiency, Equity, and Environmental) are considered. The objective is to minimize the total budget required to satisfy alpha reliability constraint of total travel time, equity ratio, and total emission, while considering the route choice behavior of network users. The problem is formulated as the chance-constrained model for application of alpha confidence level and solved as a lexicographic optimization problem to consider the multi-variable. A simulation-based genetic algorithm procedure is developed to solve this complex network design problem(NDP). A simple numerical example ispresented to illustrate the features of the proposed NDP model.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.61-66
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• 2012

We propose a traffic information service system for which traffic data are transmitted over vehicle ad-hoc network from neighbor vehicles, and eventually provided to the traffic information center through a few gateway vehicles which are capable of inter-working with the infrastructure network like 3G. The center broadcasts the traffic information through the FM radio. The proposed scheme allows collecting and analyzing traffic status of large areas without incorporating separated monitoring systems, e.g., probe cars and enables to provide accurate traffic information to drivers in timely manner. We also evaluate its performance by ns-3 simulation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.1 no.1
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• pp.52-57
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• 2002

A simulation tool for an optimal ATIS design and drivers' dynamic route choice behavior analysis is developed, which is applicable to urban networks. Due to the difficulty to make drivers feel the time pressure according to traffic conditions, current SP questionnaire survey type surveys have a limitation to capture correct driver reactions to real-time traffic Information provision. The simulator Is a web-based upgraded version, named WATiSim (Web-based ATIS Simulator), to quickly perform a wide population survey with a minimal cost using INTERNET Furthermore, the time pressure issue is lessened by its interface and simulation modules. After WATiSim mimicked a VMS based ATIS in a partial network of Seoul Metropolitan, reactions of drivers to various traffic conditions were surveyed through INTERNET and analyzed using a logit model. Drivers under the ATIS environment clearly understood the provided traffic information, and their reactions were closely related to traffic conditions, scheduled delay, trip purposes as well as toll charge if any.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.208-211
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• 2019

차량 포그 컴퓨팅 및 자율주행 자동차 개발 기술이 발전하면서 자동차 내부에 탑재된 IoT 센서들은 교통 정보 관련 다양한 정보를 수집할 수 있게 되었고, 더불어 자동차와 자동차간, 차량과 교통 인프라 간의 통신을 통해 수집된 교통 정보의 공유가 가능해졌다. 그러나 이 과정에서 알지 못하는 차량으로부터 받은 메시지를 어떻게 신뢰할 수 있는지에 대한 문제가 존재한다. 이를 보완하기 위해 평판 시스템을 적용한 연구들이 있으나 여전히 불안전한 데이터 저장방식과 통신 트래픽 문제가 존재한다. 이를 해결하기 위해 블록체인 기술을 사용된다. 본고에서는 블록체인 기반의 차량 네트워크의 평판 시스템 연구 사례를 분석한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.01a
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• pp.75-77
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• 2021

다양한 원인으로 매년 수많은 사람이 교통사고로 목숨을 잃거나 크게 다치곤 한다. 최근 교통사고 통계자료에 따르면 졸음운전으로 인한 교통사고가 음주운전이나, 과속보다도 높은 비중을 차지하고 있었다. 또한, 사고가 났을 때 안전벨트를 매지 않은 운전자나 동승객은 부상 정도가 훨씬 심각한 것으로 알려져 전 좌석에 안전벨트를 꼭 착용해야 하는 법도 제정되었다. 그런데도 많은 운전자 및 동승자가 안전벨트를 착용하지 않아 크게 부상을 당하는 사고는 줄지 않고 있다. 이러한 사고와 부상을 줄이기 위하여 본 논문에서는 다중 네트워크를 이용하여 운전자의 졸음 감지 및 운전자, 동승자의 안전벨트 착용 여부까지 실시간으로 판별하는 시스템을 설계하고 구현한다.

• Journal of Korean Society of Transportation
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• v.32 no.2
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• pp.162-169
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• 2014

This study dealt with the airport network applying the Structural Equivalence which has used in the field of social science network. It analyzed the size of aviation market and trade exchanges. The results between blocks through the Convergence of Iteration Correlation are as follows; Block 1 (major hub airport) and Block 5 (Australian and New Zealand airports) have a strong relationship between other blocks. Block 3 (CIS region) and Block 7 (Malaysia and Indonesia) have been indicated as relatively low degree. The structural equivalence analysis can be grouped as a small number of blocks with large and complex networks and also presented a significant result according to the nature of the relationship between aviation market and the level of trade exchanges.

• Journal of the Korea Computer Graphics Society
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• v.17 no.4
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• pp.23-30
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• 2011

We propose an intelligent ribbon road network for automatic vehicle simulation, and a real-time algorithm for large-scale, realistic traffic simulation based on artificial energy functions. Our method reconstructs a road network automatically from both GIS (Geographic Information System) real-world data and synthetic models. Such automatic road network helps us to easily simulate almost every possible scenario such as intersections, ramps, etc. In order to simulate agents' movement, we design car-environment interaction energy and car-car interaction energy functions. Car agents move along the road network according to the proposed energy functions while avoiding collisions with other car agents.