• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.6
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• pp.562-569
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• 2009

Recently, Hi-pass system(non-stop electric toll collection) using DSRC is working. However, it has various problems such as system errors by EM wave interference or multi-path reflection. The EM wave absorber is able to solve these problems. In this paper, we designed and fabricated EM wave absorber using amorphous substance. As a result EM wave absorber with composition of amorphous metal powder:CPE=45:55 wt.% has the thickness of 2.65 mm and absorption ability was higher than 40 dB at 5.8 GHz.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.1
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• pp.86-98
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• 2014

Currently, many OBUs(On Board Unit)s were installed on the vehicle because ETCS(Electronic Toll Collection System) using DSRC(Dedicated Short Range Communication) was constructed in the tollgate of the whole country.A research development and the commercialization utilizing the One Card All Pass and those Infrastructures of ETCS, are promoting of ITS services. Although many studies of the application method about the One Card All Pass of ETCS have been made, standards about the application method of the One Card All Pass and payment for the provision of traffic convenience, were not made clear. So we are proposed method that One Card All Pass announced by Ministry of Land, Infrastructure and Transport, takes advantage of the existing DSRC-based to apply ETCS. We have confirmed the performance of the system through a variety of driving test using three test vehicles on trial operation site and ETCS applying application method proposed in this study. As a result of driving test, we have confirmed validity of standard application method proposed in this study through the communication success rate of about 99% and analyzed problem that may occur by applying service parts of ETCS of transportation convenience facilities because of about 1% communication failure rate.

• Journal of Advanced Navigation Technology
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• v.13 no.2
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• pp.214-223
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• 2009

In this paper, we analysed and simulated the high speed mobile wireless channel for IEEE802.11p WAVE/DSRC standard draft. IEEE802.11p working group measured and suggested 6 channel model for WAVE/DSRC systems which is used for vehicle to vehicle or vehicle to infra communication. However, the models only provides numerical model, it did not provide Computer based software simulation model. So it can not be used directly for performance estimation of WAVE system. In this paper we suggested simulation technique of WAVE channel simulation which is developed S/W based WAVE channnel simulator. The simulation results for PSD, LCR, and AFD are also obtained, which can be used for performance estimation of IEEE802.11p based vehicular communication system.

• International Journal of Highway Engineering
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• v.16 no.3
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• pp.119-129
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• 2014

PURPOSES : This investigational survey is to observe a proper spatial aggregation method for path travel time estimation using the hi-pass DSRC system. METHODS : The links which connect the nodes of section detectors location are used for path travel time estimation traditionally. It makes some problem such as increasing accumulation errors and processing times. In this background, the new links composition methods for spatial aggregation are considered by using some types of nodes as IC, JC, RSE combination. Path travel times estimated by new aggregation methods are compared with PBM travel times by MAE, MAPE and statistical hypothesis tests. RESULTS : The results of minimum sample size and missing rate for 5 minutes aggregation interval are satisfied except for JC link path travel time in Seoul TG~Kuemho JC. Thus, it was additionally observed for minimum sample size satisfaction. In 15, 30 minutes and 1 hour aggregation intervals, all conditions are satisfied by the minimum sample size criteria. For accuracy test and statistical hypothesis test, it has been proved that RSE, Conzone, IC, JC links have equivalent errors and statistical characteristics. CONCLUSIONS : There are some errors between the PBM and the LBM methods that come from dropping vehicles by rest areas. Consequently, this survey result means each of links compositions are available for the estimation of path travel time when PBM vehicles are missed.

• International Journal of Highway Engineering
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• v.16 no.5
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• pp.99-108
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• 2014

PURPOSES : The travel times of expressway buses have been estimated using the travel time data between entrance tollgates and exit tollgates, which are produced by the Toll Collections System (TCS). However, the travel time data from TCS has a few critical problems. For example, the travel time data include the travel times of trucks as well as those of buses. Therefore, the travel time estimation of expressway buses using TCS data may be implicitly and explicitly incorrect. The goal of this study is to improve the accuracy of the expressway bus travel time estimation using DSRC-based travel time by identifying the appropriate analysis period of input data. METHODS : All expressway buses are equipped with the Hi-Pass transponders so that the travel times of only expressway buses can be extracted now using DSRC. Thus, this study analyzed the operational characteristics as well as travel time patterns of the expressway buses operating between Seoul and Dajeon. And then, this study determined the most appropriate analysis period of input data for the expressway bus travel time estimation model in order to improve the accuracy of the model. RESULTS : As a result of feasibility analysis according to the analysis period, overall MAPE values were found to be similar. However, the MAPE values of the cases using similar volume patterns outperformed other cases. CONCLUSIONS : The best input period was that of the case which uses the travel time pattern of the days whose total expressway traffic volumes are similar to that of one day before the day during which the travel times of expressway buses must be estimated.

• Journal of Advanced Navigation Technology
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• v.4 no.2
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• pp.171-181
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• 2000

In this paper, we propose an AVLS(Automatic Vehicle Location System) using the DSRC(Dedicated Short Range Communication) which adopts a radio communication tool between RSE(Road-Side Equipment) and OBE(On-Board Equipment) on a vehicle and uses the ISM bandwidth of 5.8GHz radio frequency. Typical AVLS uses the sensors for detecting the vehicle, but the DSRC system is developed for supporting various services such as the position of vehicle, clearance, vehicle to vehicle communication, collection and distributions of traffic and road information. Also, for fast processing, we design three-layer configuration of physical(L1), data link(L2), and application layer(L7), which simplifies the seven-layer configuration. We suggest the proposed system as a new technology for replacement of typical wireless communication system and sensors for AVLS.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.394-399
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• 2006

In this paper, we investigated performance for 5.8GHz dedicated short range communication system using OFDM which will be applied to Intelligent transportation system services. The maximum speed of a vehicle in DSRC channel is very fast as 180km/h, so a service time is very short to serve a various traffic information if hand-off is not occurred. Therefore higher bit rate is required to proved advanced and intelligent service to the drivers of various vehicle and the data transmission rate of the next generation DSRC system if being promoted over 10Mbps. The signals received in Clarke & Gans channel have been simulated using the computer simulator.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.38-48
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• 2017

Link attributes, such as speed, occupancy, and flow, are essential factors for transportation planning and operation. It is, therefore, one of the most important decision-making problems in intelligent transport system (ITS) to determine the optimal location of a sensor for collecting the information on link attributes. This paper aims to develop a model to determine the optimal location of a sensor to minimize the variability of traffic information on whole networks. To achieve this, a network sensor location model (NSLM) is developed to reflect discrete characteristics of data collection. The variability indices of traffic information are calculated based on the summation of diagonal elements of the variance-covariance matrix. To assess the applicability of the developed model, speed data collected from the dedicated short range communication (DSRC) systems were used in Daegu metropolitan area. The developed model in this study contributes to the enhancement of investment efficiency and the improvement of information accuracy in intelligent transport system (ITS).

• Journal of the Korea Society of Computer and Information
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• v.26 no.9
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• pp.133-141
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• 2021

The development and demand for the system that provides users with traffic information and efficient road use have continued. also, this system provides the basic technology of the Intelligent Transport System (ITS). The most used traffic information collection tools are Vehicle detectors (VDS) and short-range wireless communication (DSRC) on express way. In order to generate reliable traffic information, it is necessary to efficiently manage and utilize the collected data as well as high-quality traffic data collection and processing technology. In this study, traffic information collection·processing·provision systems were investigated, and analyze the current status and problems of traffic information collected through VDS. Based on this, we would like to present an improved collection algorithm that utilizes the Kalman filter for vehicle information measurement of VDS data. By using the algorithm of this study, it is possible to minimize the time delay of the estimated value as well as the noise removal that inevitably occurs during measurement.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.1
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• pp.92-100
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• 2008

The existing transportation systems is emerged as a major obstacle to solve the problems such as a traffic jam and the increasing cost for a distribution and a traffic safety. In hun, ITS targeting intellectual vehicles and transportation infrastructure like road and signals is getting more important and the standards of ITS wireless communication is also getting attention. New traffic control strategies are being developed to utilize real-time traffic information collected by detection method using ITS wireless technology. Especially, DSRC system is being expanded wit ETCS and the use of OBU is spreading. These infrastructures will have much influence on ITS industry and a profound study on the method of utilizing a present infrastructure is going on in various fields. The optimum traffic signal control system using quality real-time information through these infrastructure is under development and so is WISDOM. Accordingly, this paper proposes communication protocol utilizing DSRC to collect real-time traffic information in WISDOM.