• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4D
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• pp.459-465
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• 2009

u-T (ubiquitous transportation) environment can be envisioned as an advanced version of ITS environment and be expected to provide more advanced transportation service in a ubiquitous manner. As a basic necessity to measure traffic flow in both environments, a flow estimation method was proposed. Flows have been measured in existing ITS and in a new u-T environments and some differences were investigated using simulation technique. In the interrupted traffic situation, the flow rate of u-T is 3.58% higher than that in ITS environment. Both MARE and MAE, which were used as measure of effectiveness, in u-T were better since the results are 31.4% and 31.1% lower than in ITS, respectively. Besides the equality coefficient in u-T was 1.9% higher than that in ITS. Such being the case, the flow rate measured in u-T using U-TSN is more reliable and can be expected to be successfully used for transportation system design or traffic operation areas.

• Journal of Korean Society of Transportation
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• v.26 no.3
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• pp.179-186
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• 2008

It is crucial in traffic flow management to maintain productivity and the traffic stability at the same time especially under congested traffic conditions. This issue has not been explicitly addressed under the intelligent transportation system environments. However, the ubiquitous transportation system environments make it possible to collect the data for each vehicle's position and velocity and to perform more sophisticated traffic flow management at individual vehicle or platoon level through V2V and V2I communications. In this paper, a preventive traffic flow management scheme is proposed, in which the objective is to maintain traffic flow stability while the productivity of the system is not decreased. The management scheme is proposed based on Greenshield's model because it is simple and easy to handle. It is considered that further research should be performed to evaluate the various traffic flow models.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.4
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• pp.157-162
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• 2009

This study's purpose is to forecast the market demand of UVS (u-Transportation Vehicle Sensor) OBU (On-board Unit) of the ubiquitous Transportation. Bass model, Logistic model, and Gompertz model were used for the forecasting market demand. Firstly, this research focused on the market size for the u-T OBU. All three models were used for the market size prediction and the average values were used. The Bass model were calibrated and the market demand for the UVS OBU of the u-Transportation system were estimated using this model.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.5
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• pp.61-72
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• 2013

Next-generation ITS(Intelligent Transportation System) adopts WAVE(Wireless Access in Vehicular Environment) system which is capable of the bidirectional communication system in vehicular environments. u-Transportation system adopted WAVE communications system to show the optimal performance in terms of various services with regard to vehicle safety and traffic. In this paper, we introduce testbed of ubiquitous-Transportation system and its service. Then, we describe WAVE system for supporting next-generation ITS service. Also, we carried out tests in real road environments in order to verify communication functions of WAVE systems and its performance. We confirmed that our communication systems for supporting services meet the communication performance.