• Journal of Korean Society of Transportation
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• v.23 no.6 s.84
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• pp.19-30
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• 2005

The objective of this research is to keep track of path travel time using methods of collecting traffic data. Users of traffic information are looking for extensive information on path travel time, which is referred to as the time taken for traveling from the origin to the destination. However, all the information available is the average path travel times, which is a simple sum of the average link travel times. The average path travel time services are not up to the expectation of traffic information consumers. To improve provide more accurate path travel time services, this research makes a number of different estimates of various path travel times on one path, assuming it will be under the same condition, and provides a range of estimates with their probabilities to the consumers, who are looking for detailed information. To estimate the distribution of the path travel times as a combination of link travel times. this research analyzes the relation between the link travel time and path travel time. Based on the result of the estimation. this research develops the algorithm that combines the distribution of link travel time and estimates the path travel time based on the link travel times. This algorithm was tested and proven to be highly reliable for estimating the path traffic time.

• 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.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.1
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• pp.79-88
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• 2018

With the increasing popularity of electronic toll collection system using 5.8 GHz dedicated short-range communications (DSRC) technology, DSRC-based travel-time collection systems have been deployed on major urban and rural arterial routes in Korea. However, since probe sample sizes are frequently insufficient in probe-based systems, the gathered travel times from probe vehicles fluctuate significantly compared to those of the population; as a result, the accuracy of the collected travel times could decrease. To mitigate the fluctuations (also known as biases), smoothing techniques need to be applied. In this study, some smoothing techniques-moving average, the Loess, and Savitzky-Golay filtering-were applied to probe travel times. Resultantly, the error in the smoothed travel times at the lowest sampling plan (5%) decreased as much as 45% compared to those in non-smoothed travel times. The results of this study can be practically applied to probe-based travel-time estimation systems for providing reliable travel times along the travel corridor.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.1
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• pp.34-45
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• 2006

In this study comparison estimates travel times with observed travel time. In generally, peak flood discharges decrease become travel times longer. It is closely related to storage constant for the watershed routing of a flood. There are so many empirical formulas available for the estimation of travel time, storage coefficients and lag time but results computed generally show great different depending on individual formulas. When calculated flood discharge depend on the travel times varying the discharge. In this study the Wichun travel time shorter optimization travel time than observed travel time for the rusa and memi. There are showed good results for flood discharges, water level and velocity of the memi at the Younggok.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.2
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• pp.14-26
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• 2009

This study presented a novel method to estimate travel times under incident conditions. Predictive travel time information was defined and evaluated with the proposed method. The proposed method utilized individual vehicle speeds obtained from global positioning systems (GPS) and inter-vehicle communications(IVC) for more reliable real-time travel times. Individual vehicle trajectory data were extracted from microscopic traffic simulations using AIMSUN. Market penetration rates (MPR) and IVC ranges were explored with the accuracy of travel times. Relationship among travel time accuracy, IVC ranges, and MPR were further identified using regression analyses. The outcomes of this study would be useful to derive functional requirements associated with traffic information systems under forthcoming ubiquitous transportation environment

• Proceedings of the KOR-KST Conference
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• 1999.10a
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• pp.249-254
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• 1999

• Journal of the Korean Mathematical Society
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• v.38 no.4
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• pp.711-722
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• 2001

We survey recent results on the inverse kinematic problem arising in geophysics. The question is whether one can determine the sound speed (index of refraction) of a medium by measuring the travel times of the corresponding ray paths. We emphasize the anisotrpic case.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5D
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• pp.739-746
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• 2006

The bus probe-based link travel times were more readily available due to bus' fixed route schedule and it was different from that of taxi-based one in its value for the same link. At the same time, the bus-based one showed less accurate information than the taxi-based link travel time, in terms of reliability expressed by 1-RMSE(%) measure. The purpose of this thesis is to develop a heuristic algorithm for mixing both sources-based link travel times. The algorithm used both real-time and historical profile travel times. Real-time source used 4 consecutive periods' average and historical source used average value of link travel time for various congestion levels. The algorithm was evaluated for Seoul urban arterial network 3 corridors and 20 links. The results based on the developed algorithm were superior than the mere fusion based link travel times and the reliability amounted up to 71.45%. Some limitation and future research agenda have also been discussed.

• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.81-86
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• 2001

Ultrasonic travel-times obtained with the LCR ultrasonic technique have shown an ability to distinguish among three aluminum plates. The 244$\times$150mm thick, but differ in heat treatment. One is fully annealed, the second is quenched and then tempered, and the third is heat-treated to T651 plate, as received plate. Travel-times were obtained at four locations on each side of all plates. The data for both sides of each plate clearly are in very close agreement except location 1 of each plate. In order to show travel-time variation throughout the plate areas, the average travel-time for both sides of each plate were calculated. For Plate 1, the travel-time data were the highest and the data of Plate, the travel-time data were the highest and the data of Plate 2 were upper than Plate 3. Finally, the residual stresses for each plate were measured by X-ray diffraction method. The results showed a good relation. These preliminary results indicate that the LCR Ultrasonic Technique may be not only further developed for use in quality control in the manufacture of rolled aluminum plates but also industry.

• 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.