• Journal of Korean Society of Transportation
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• v.23 no.6 s.84
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• pp.71-80
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• 2005

With rapid development Telematics industry, the concern of dynamic road pricing system is increasing. In this study, the change of traffic flows according to traffic information and variation of congestion road prices related to the dynamic road pricing was analyzed. In this study, three facts were unfolded. First, high delay penalty and low delay penalty drivers are shown different reaction for the different congestion road prices. Second, the higher congestion road prices the more drivers convert their route from toll road to non toll road. Third, high penalty drivers are converting to toll road than low delay penalty drivers under same congestion road prices. This study has reached the conclusion that dynamic congestion pricing has a high possibility for traffic management.

• Smart Structures and Systems
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• v.14 no.3
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• pp.469-477
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• 2014

As a kind of intelligent materials, conductive asphalt concrete has a broad application prospect including melting ice and snow on the pavement, closing cracks in asphalt concrete, sensing pavement damage, and so on. Conductive pavement will be suffered from fatigue failure as conventional pavement in the process of service, and this fatigue damage of internal structure can be induced by electrical signal output. The characteristics of electrical signal variation of conductive asphalt concrete in the process of fatigue cracking were researched in this paper. The whole process was clearly divided into three stages according to resistance changes, and the development of fatigue damage wasn't obvious in stage I and stage II, while in stage III, the synchronicity between the resistance and damage began to appear. Thus, fatigue damage variable D and initial damage value $D_0$ represented by the functions of resistance were introduced in stage III. After calculating the initial damage value $D_0$ under different stress levels, it was concluded that the initial damage value $D_0$ had no noticeable change, just ranged between 0.24 and 0.25. This value represented a critical point which could be used to inform the repair time of early fatigue damage in the conductive asphalt pavement.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.34-35
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• 2019

The objective of this study is to analyze the risk of collision accidents to the VTSOs(Vessel Traffic Service Operators) as small vessels are expanded for monitoring targets. For this purpose, the risks of accidents and quasi-incidents involving small ships in the VTS area were analyzed by the collision risk model(CoRI) from the view-point of VTSOs. In addition, by analyzing risk of whether or not small vessels are included in the monitoring target by CoRI, we will contribute to the preparation of a proper range of the vessel for monitoring taget through various case studies in the future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.17-24
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• 2005

Traditional Internet applications such as FIP and E-mail are increasingly sharing bandwidth with newer, more demanding applications such as Web browsing, IP telephony, video conference and online games. These new applications require Quality of Service (QoS), in terms of delay, loss and throughput that are different from QoS requirements of traditional applications. Unfortunately, current Active Queue Management (AQM) approaches offer monolithic best-effort service to all Internet applications regardless of the current QoS requirements. This paper proposes and evaluates a new AQM technique, called MCDT that provides dynamic and separated buffer threshold for each Applications, those are FTP and e-mail on TCP traffic, streaming services on tagged UDP traffic, and the other services on untagged UDP traffic. Using a new QoS metric, our simulations demonstrate that MCDT yields higher QoS in terms of the delay variation and a packet loss than RED when there are heavy UDP traffics that include streaming applications and data applications. MCDT fits the current best-effort Internet environment without high complexity.

• Journal of the Korea Society for Simulation
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• v.15 no.1
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• pp.27-33
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• 2006

To guarantee QoS (Quality of Service), routers should determine routing paths satisfying service requirements, based on link state information as well as network topology. Link status database (LSD) in routers should be efficiently managed to effectively reflect the current state of all links. However, there is a trade off between the exact reflection of the current link status and its update cost. For exactly reflecting the current link status, each router immediately notifies its neighbors that link state information is changed. This may degrade performance of the router due to the processing of link state update messages. On the other side, if the current link state information is not updated appropriately, a route setup request can be rejected because of the discrepancy between the current link state information and previously updated link state information in LSD. In this paper, we propose a traffic variation based link state update algorithm for adaptively controlling the generation of link state update messages and compare its performance with those of four existing algorithms by intensive simulations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.31-38
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• 2020

The characteristics of ship traffic routes and the long term fluctuation in marine traf ic volume of the incoming and outgoing routes of the Yeosu Gwangyang Port were analyzed using vessel traffic data from the past 22 years and a real-time vessel traffic volume survey performed for 72 hours per year, for three years, between 2015 and 2017. As of 2017, the number of vessels passing through Yeosu Gwangyang Port was about 66,000 and the total tonnage of these ships was about 804,564 thousand tons, which is a 400 % increase from the 189,906 thousand tons shipped in 1996. Specifically, the dangerous cargo volume was 140,000 thousand tons, which is a 250 % increase compared to 1996. According to the real-time vessel traffic volume survey, the average daily number of vessels was 357, and traf ic route utilization rates were 28.1 % in the Nakpo sea area, 43.8 % in the specified sea area, and the coastal area traf ic route, Dolsan coastal area, and Kumhodo sea area showed the same rate of 6.8 %. Many routes meet in the Nakpo sea area and, parallel and cross passing were frequent. Many small work vessels entered the specific sea area from the neighboring coastal area traffic route and frequently intersected the path of larger vessels. The anchorage waiting rate for cargo ships was about 24 %, and the nightly passing rate for dangerous cargo ships such as chemical vessels and tankers was about 20 %. Although the vessel traffic volume of Yeosu Gwangyang Port increases every year, the vessel traffic routes remain the same. Therefore, the risk of accidents is constantly increasing. The route conditions must be improved by dredging and expanding the available routes to reduce the high risk of ship accidents due to overlapping routes, by removing reefs, and by reinforcing navigational aids. In addition, the entry and exit time for dangerous cargo ships at high-risk ports must be strictly regulated. Advancements in the VTS system can help to actively manage the traffic of small vessels using the coastal area traffic route.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.57-66
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• 2007

Weaving is defined as the crossing of two or more traffic streams traveling in the same general direction along a significant length of highway without the aid of traffic control devices. Compared with other freeway sections, perturbation is easy to happen at weaving section. Because there are a lot of lane-changing maneuvers at the weaving section, traffic is subject to turbulence in excess of that normally presents on freeway basic section. This turbulence causes operational problems and its impact must be considered. The purpose of this paper is to perform a basic study on flow characteristics by lane, which can be achieved through analyzing breakdown phenomenon in the microscopic approach. The study made use of data derived from the aerial photography for the microscopic analysis. This research produced the 30-second interval data such as flows, speeds, and densities for the macroscopic analysis and derived the vehicular data to draw time-space diagram for the microscopic analysis. The paper analyzed the traffic characteristics using flows, speeds and densities variation and investigated the conditions of breakdown occurrence with the time-space diagrams. The breakdown phenomenon was identified at weaving section and the propagation from free flow to synchronized flow was observed in this study. In the future, the findings help develop the traffic operational algorithm to manage the traffic congestion under ubiquitous circumstance since the conditions of breakdown Phenomenon can be understood more.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.167-173
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• 2009

It is important to study on the traffic accident severity reduction because traffic accident is an issue that is directly related to human life. Therefore, this research developed countermeasure to reduce traffic accident severity considering various factors that affect the accident severity. This research developed the Accident Severity Prediction Model using the collected accident data from Seohaean Expressway in 2004~2006. Through this model, we can find the influence factors and methodology to reduce accident severity. The results show that speed limit violation, vehicle defects, vehicle to vehicle accident, vehicle to person accident, traffic volume, curve radius CV(Coefficient of variation) and vertical slope CV were selected to compose the accident severity model. These are certain causes of the severe accident. The accidents by these certain causes present specific sections of Seohaean Expressway. The results indicate that we can prevent severe accidents by providing selected traffic information and facilities to drivers at specific sections of the Expressway.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.146-170
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• 2017

Joint channel assignment and routing is a well-known problem in multi-radio wireless mesh networks for which optimal configurations is required to optimize the overall throughput and fairness. However, other objectives need to be considered in order to provide a high quality service to network users when it deployed with high traffic dynamic. In this paper, we propose a re-configuration optimization model that optimizes the network throughput in addition to reducing the disruption to the mesh clients' traffic due to the re-configuration process. In this multi-objective optimization model, four objective functions are proposed to be minimized namely maximum link-channel utilization, network average contention, channel re-assignment cost, and re-routing cost. The latter two objectives focus on reducing the re-configuration overhead. This is to reduce the amount of disrupted traffic due to the channel switching and path re-routing resulted from applying the new configuration. In order to adapt to traffic dynamics in the network which might be caused by many factors i.e. users' mobility, a centralized heuristic re-configuration algorithm called State-Aware Joint Routing and Channel Assignment (SA-JRCA) is proposed in this research based on our re-configuration model. The proposed algorithm re-assigns channels to radios and re-configures flows' routes with aim of achieving a tradeoff between maximizing the network throughput and minimizing the re-configuration overhead. The ns-2 simulator is used as simulation tool and various metrics are evaluated. These metrics include channel-link utilization, channel re-assignment cost, re-routing cost, throughput, and delay. Simulation results show the good performance of SA-JRCA in term of packet delivery ratio, aggregated throughput and re-configuration overhead. It also shows higher stability to the traffic variation in comparison with other compared algorithms which suffer from performance degradation when high traffic dynamics is applied.

• Journal of Korean Society of Transportation
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• v.23 no.2
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• pp.107-116
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• 2005

The information on travel time in providing the information of traffic to drivers is one of the most important data to control a traffic congestion efficiently. Especially, this information is the major element of route choice of drivers, and based on the premise that it has the high degree of confidence in real situation. This study developed a vehicle arrival time prediction algorithm called as "VAT-DV" for 6 corridors in total 6.1Km of "Nam-san area trffic information system" in order to give an information of congestion to drivers using VMS, ARS, and WEB. The spatial scope of this study is 2.5km~3km sections of each corridor, but there are various situations of traffic flow in a short period because they have signalized intersections in a departure point and an arrival point of each corridor, so they have almost characteristics of interrupted and uninterrupted traffic flow. The algorithm uses the information on a demand volume and a queue length. The demand volume is estimated from density of each points based on the Greenburg model, and the queue length is from the density and speed of each point. In order to settle the variation of the unit time, the result of this algorithm is strategically regulated by importing the AVI(Automatic Vehicle Identification), one of the number plate matching methods. In this study, the AVI travel time information is composed by Hybrid Model in order to use it as the basic parameter to make one travel time in a day using ILD to classify the characteristics of the traffic flow along the queue length. According to the result of this study, in congestion situation, this algorithm has about more than 84% degree of accuracy. Specially, the result of providing the information of "Nam-san area traffic information system" shows that 72.6% of drivers are available.