• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.1
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• pp.67-74
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• 2022

In recent, the number of real-time traffic information sources and providers has increased as increasing smartphone users and intelligent transportation system facilities installed at roadways including vehicle detection system (VDS), dedicated short-ranged communications (DSRC), and global positioning system (GPS) probe vehicle. The accuracy of such traffic information would vary with these heterogeneous information sources or spatiotemporal traffic conditions. Therefore, the purpose of this study is to propose an empirical strategy of heterogeneous information fusion to improve the accuracy of real-time traffic information. To carry out this purpose, travel speed data collection based on the floating car technique was conducted on 227 freeway links (or 892.2 km long) and 2,074 national highway links (or 937.0 km long). The average travel speed for 5 probe vehicles on a specific time period and a link was used as a ground truth measure to evaluate the accuracy of real-time heterogeneous traffic information for that time period and that link. From the statistical tests, it was found that the proposed fusion strategy improves the accuracy of real-time traffic information.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.2
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• pp.15-25
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• 2007

This paper aims at testing the applicability of RFID (radio frequency identification) based link travel time estimation algorithm in urban street settings in Jeju island Korea. For this, we developed algorithm and compared link travel times derived from the RFID probe based algorithm with those from (already available) GPS based link travel time estimation algorithm and with the actual link travel times from survey. RFID readers are composed of master reader and slave reader and the participating passenger cars were supposed to be equipped with RFID tag inside the vehicle. The data were sent to traffic information center and we used those data in comparison. The algorithm produced link travel times in a successful manner and the accuracy of those link travel times was about 88%. For the same link segments, the accuracy of GPS based link travel times was 93%. The t-test showed that both RFID and GPS based link travel times were not different in accuracy from statistical point of view. The applicability of RFID was tested successfully and the algorithm proposed seemed to be used in similar urban settings. Some limits and future research agenda have also been presented.

• Journal of Korea Spatial Information System Society
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• v.10 no.3
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• pp.55-65
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• 2008

For obtaining telematics traffic information(travel time or speed in an individual link), there are many kinds of devices to collect traffic data. Since the GPS satellite signals have been released to civil society, thank to the development of GPS technology, the GPS has become a very useful instrument for collecting traffic data. GPS can reduce the cost of installation and maintenance in contrast with existing traffic detectors which must be stationed on the ground. But. there are Problems when GPS data is applied to the existing filtering techniques used for analyzing the data collected by other detectors. This paper proposes a method to provide users with correct traffic information through filtering abnormal data caused by the unusual driving in collected data based on GPS. We have developed an algorithm that can be applied to real-time GPS data and create more reliable traffic information, by building patterns of past data and filtering abnormal data through selection of filtering areas using Quartile values. in order to verify the proposed algorithm, we experimented with actual traffic data that include probe cars equipped with a built-in GPS receiver which ran through Gangnam Street in Seoul. As a result of these experiments, it is shown that link travel speed data obtained from this algorithm is more accurate than those obtained by existing systems.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.4
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• pp.73-79
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• 2015

Enhanced bandwidths of the GPS microstrip patch antennas applied by a Wilkinson power divider and a quadrature hybrid were compared. The square patch was designed, and fed by the two port probes for the circuit application. The Wilkinson power divider and quadrature hybrid circuit were designed, and applied to the patch antenna. The designed patch and two circuits were implemented on the FR4 board, and combined together. The measurement of the bandwidth within a voltage standing wave ratio (VSWR) of 2: 1 were 36.5% (1,200~1,775 MHz) in the case of the Wilkinson power divider and 29.84% (1,230~1,700 MHz) in the case of the quadrature hybrid. Axial ratios (AR) in 3dB were 17.14% bandwidth (1,360~1,630 MHz) and 15.87% bandwidth (1,400~1,650 MHz), respectively. The application of the Wilkinson power divider is wider than that of the quadrature hybrid. The peak gains in the anechoic chamber at the GPS center frequency were measured as 2.84 dBi and 2.75 dBi, respectively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.5
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• pp.70-81
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• 2020

Point-by-point data, which is abundantly collected by vehicles with embedded GPS (Global Positioning System), generate useful information. These data facilitate decisions by transportation jurisdictions, and private vendors can monitor and investigate micro-scale driver behavior, traffic flow, and roadway movements. The information is applied to develop app-based route guidance and business models. Of these, speed data play a vital role in developing key parameters and applying agent-based information and services. Nevertheless, link speed values require different levels of physical storage and fidelity, depending on both collecting and reporting intervals. Given these circumstances, this study aimed to establish an appropriate collection interval to efficiently utilize Space Mean Speed information by vehicles with embedded GPS. We conducted a comparison of Probe-vehicle data and Image-based vehicle data to understand PE(Percentage Error). According to the study results, the PE of the Probe-vehicle data showed a 95% confidence level within an 8-second interval, which was chosen as the appropriate collection interval for Probe-vehicle data. It is our hope that the developed guidelines facilitate C-ITS, and autonomous driving service providers will use more reliable Space Mean Speed data to develop better related C-ITS and autonomous driving services.

• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.67-77
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• 2004

A treatment of outlier has been discussed. Outliers disrupt the reliability of information systems and they should be eliminated prior to the information and/or data fusion. A time series-based elimination algorithm were proposed and prediction interval, as a criterion of acceptable value width, was obtained with the model. Ten actual link values were used and the best model was identified as IMA(1,1). Although the actual verification was difficult in a sense that the matching process between the eliminated data and model data was not readily available, the proposed model can be successfully used in practice with some calibration efforts.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.4
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• pp.156-161
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• 2015

In this paper, a dual-polarized multi-band multi-layer antenna for a vehicle, which operates in the GPS, bluetooth, and DSRC bands, was implemented. The antenna was designed as a multi-layer structure, and a FR4-epoxy substrate with =4.4 and =1.6mm was used. GPS and DSRC antennas have circular polarized characteristics, and a single probe feeding method was applied. Simulated results by Ansys HFSS v11 was compared with the measured ones. The size of the optimally designed antenna is $67mm{\times}67mm{\times}4.8mm$, -10dB bandwidth of the anatenna was measured to be 820MHz, 127MHz, and 862MHz in each band, and 3dB AR bandwidth of the antenna was simulated to be 19MHz and 110MHz in GPS and DSRC bands. The results confirmed that suggested system satisfies the system requirements.

• Journal of Korean Society of Transportation
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• v.30 no.3
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• pp.43-55
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• 2012

Bicycle is an environment-friendly transport mode contributing to a more sustainable transportation systems. To innovatively increase the use of bicycle as a significant transport mode, bicycle-friendly roadway environment should be provided. This study proposes a method to evaluate cycling environment based on the analysis of data collected from an specially equipped probe bicycle. The inertial measurement unit(IMU) consisting of a gyro sensor, accelerometer, and a global positioning systems(GPS) receiver was installed on the probe bicycle. Cycling stability index(CSI) and bicycle speed data were used as inputs of the proposed evaluation framework adopting the Fault Tree Analysis, which is a well-known technique for the risk analysis. The outcomes of this study will serve as an intelligent assesment tool for cycling environment.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.3
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• pp.10-24
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• 2014

Bicycle is a useful transportation mode that is healthy, emission-free, and environmentally compatible. Although large efforts have been made to promote the use of bicycling to date, there still exist various hurdles and limitations. One of the key issues to increase bicycling is how to gather bicycle-related data from the field and to generate valuable information for both users and operations agencies. This study proposes a method to process bicycle trajectory data which is obtained from tracing global positioning systems(GPS) equipped bicycle, which is defined as the probe bicycle. The proposed method is based on the concept of statistical quality control of data. In addition, a data collection and processing scenario in support of public bicycle system is presented. The outcomes of this study would be valuable fundamentals for developing bicycle traffic information systems that is a part of future intelligent transportation systems(ITS).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.164-175
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• 2019

Installation of digital tachograph, black box, and ADAS have been enforced to commercial vehicles for preventing violent driving and accidents by the Traffic Safety Act in Korea. Nevertheless, the damage caused by road hazards has increased 1.5 times in 2016 compared to 2013. So, developing new technologies that can identify road hazard using the sensors installed in commercial vehicles are conducting by the Ministry of Land, Infrastructure and Transport. As a part of the technologies, this research analyze the error range of GPS installed in commercial vehicles that vary according to the driving speed. As a result, the average error was 9.72m at the driving speed of 100km/h, and the error was 2.1 times larger than the average error of 4.69m at the driving speed of 40km/h. The event point proper integration/separation range(m) was analyzed to be 20m with a recognition rate of 90% or more at the same point regardless of driving speed. The results of this research can be used as basic data for improving the accuracy of location-based data would be collected using commercial vehicles.