• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.99-111
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• 2018

Service areas in expressways are very important facilities in terms of efficient expressway operation and the convenience of users. It needs a traffic management strategy to inform drivers in advance about congestion in service areas so as to distribute users of service areas. But due to the lack of sensors and data on numbers of people in the service areas, congestion in service areas had not been measured and managed appropriately. In this study, a congestion index for service areas was developed using telecommunication floating population big data. Two alternative indices (i.e., density of service areas and floating population V/c of service areas) were developed. Finally, the floating population V/c of service areas was selected as a congestion index for service areas for reasons of the ease of understanding and comparison.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3809-3822
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• 2017

Wireless Sensor Networks hold the limelight because of significant potential for distributed sensing of large geographical areas. The radio duty cycling mechanism that turns off the radio periodically is necessary for the energy conservation, but it deteriorates the network congestion when the traffic load is high, which increases the packet loss and the delay too. Although many papers for WSNs have tried to mitigate network congestion, none of them has mentioned the congestion problem caused by the radio duty cycling of MAC protocols. In this paper, we present a simple and efficient congestion control technique that operates on the radio duty cycling MAC protocol. It detects the congestion by checking the current queue size. If it detects the congestion, it extends the network capacity by adding supplementary wakeup times. Simulation results show that our proposed scheme highly reduces the packet loss and the delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9A
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• pp.916-922
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• 2007

Wireless networks (WNs) are developed and applied widely in a lot of areas. Now, a new generation of wireless networks is coming, and that is Wireless Mesh Network (WMN). At present, there are not so many researches which deal on this area. Most researches are derived from Mobile Ad hoc Networks (MANET) and WNs. In WMNs, there are some applications that require real-time delivery. To guarantee this, rate control and congestion control are needed. This problem leads to optimization issue in transport layer. In this paper, we propose a mathematical model which is applied in rate and congestion control in WNMs. From this model, we optimize rate and congestion control in WMNs by maximizing network utility. The proposed algorithm is implemented in distributed way both in links and sources.

• Journal of Navigation and Port Research
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• v.47 no.4
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• pp.212-219
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• 2023

Vessel Traffic Service (VTS) area presents a complex traffic pattern due to ships entering or leaving the port to utilize port facilities, as well as ships passing through the coastal area. To ensure safe and efficient management of maritime traffic, VTS operators continuously monitor and control vessels in real time. However, during periods of high traffic congestion, the workload of VTS operators increases, which can result in delayed or inadequate VTS services. Therefore, it would be beneficial to predict traffic congestion and congested areas to enable more efficient traffic control. Currently, such prediction relies on the experience of VTS operators. In this paper, we defined vessel traffic congestion from the perspective of a VTS operator. We proposed a method to generate traffic networks using historical navigational data and predict traffic congestion and congested areas. Experiments were performed to compare prediction results with real maritime data (Daesan port VTS) and examine whether the proposed method could support VTS operators.

• Journal of Korean Society for Geospatial Information Science
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• v.12 no.4 s.31
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• pp.53-60
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• 2004

Congestion index is needed for quantifying congestion level for various areas. So far, the index has been calculated based on multiple vehicle data for specified time interval. Such being the case, it was costly to build it and the usage of it was focused on policy development and evaluation rather than on traffic information provision. This study focuses on a development on a single vehicle based congestion index which can be a representative value for link congestion level and link speed information at the same time for dual purposes of traditional usages and information provision. A new term has been added for representing real time based arterial congestion level and it has been verified on a real time basis. The index was based on single vehicle GPS data and seemed to be cost effective in deriving the index. With the help of the index, the traffic information contents can be diversified in a constructive way in providing real time traffic information for ITS area and in using congestion level determination for traditional transportation areas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.125-132
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• 2017

Vehicular safety service reduces traffic accidents and traffic congestion by informing drivers in advance of threats that may occur while driving using vehicle-to-vehicle (V2V) communications in a wireless environment. For vehicle safety services, every vehicle must broadcasts a Basic Safety Message(BSM) periodically. In congested traffic areas, however, network congestion can easily happen, reduce the message delivery ratio, increase end-to-end delay and destabilize vehicular safety service system. In this paper, to solve the network congestion problem in vehicle safety communications, we approximate the relationship between channel busy ratio and the number of vehicles and use it to estimate the total network congestion. We propose a new context-aware transmit power control algorithm which controls the transmission power based on total network congestion. The performance of the proposed algorithm is evaluated using Qualnet, a network simulator. As a result, the estimation of total network congestion is accurately approximated except in specific scenarios, and the packet error rate in vehicle safety communication is reduced through transmit power control.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.316-323
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• 1995

This paper presents an image processing technique to get traffic information such as vehicle volume, velocity, and occupancy for measuring the traffic congestion rate. To obtain these information, two horizontal lines are previously set on the screen. A moving vehicle is detected using the gray level difference on each line, and also template matching method at night. Threshold values are determined by sampling pavement grey level, and updated dynamically to cope with the change of ambient light conditions. These technique is successfully used to calculate vehicle volume, occupancy, and velocity. This study can be applied to traffic signal control system for minimizing traffic congestion in urban areas.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2448-2454
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• 2008

Urban areas face congestion problems that diminish personal mobility and freight-transportation productivity. An increasing number of experts suggest that separating freight traffic from passenger traffic makes sense in terms of economics, the environment, and safety. Some experts suggest that underground freight transportation are the solution. The objective of this paper is to review the potential benefits and limitations of freight pipelines as a viable mode of cargo transport that can alleviate congestion on urban highways.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.181-199
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• 2011

Concentration of people in urban areas and development around Metro make exceed the passenger number which was calculated when the Metro station was built, in the result the Metro stations are crowed this is the study on the improvement of Metro station's congestion in urban areas for ensuring the passenger safety, the space of evacuation path and promoting the more pleasant riding environment with an environmental- friendly approach.

• Journal of the Korean Society of Safety
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• v.24 no.5
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• pp.113-121
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• 2009

The objective of this study is to develop highway advisory radio service for road safety oriented system design of the point by regional groups or geographical distributions. To develop these highway advisory radio service, traffic information provided service areas, responds for incident and accident, and road condition in service sections based on traffic information of highway advisory radio service. This study contributes to service of traffic information for safety driving, which is transport congestion areas and recognition of traffic congestion status in advanced traffic information service. As result of this study, systematic design of the advanced highway and traffic safety guides to management systems by highway advisory radio service.