• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.205-215
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• 2008

As static traffic assignment has reached its limitation with ITS policy applications and due to the increase of interest in studies of ITS policies since the late 1980's, dynamic traffic assignment has been considered a tool to overcome such limitations. This study used the Dynameq program, which simulates route choice behavior by macroscopic modeling and dynamic network loading and traffic flow by microscopic modeling in consideration of the feasibility of the analysis of practical traffic policy. The essence of this study is to evaluate the feasibility for analysis in practical transportation policy of using the dynamic traffic assignment technique. The study involves the verification of the values estimated from the dynamic traffic assignment with South Korea's expressway network and dynamic O/D data by comparing results with observed link traffic volumes. This study used dynamic O/D data between each toll booth, which can be accurately obtained from the highway Toll Collection System. Then, as an example of its application, exclusive bus-lane policies were analyzed with the dynamic traffic assignment model while considering hourly variations.

• Journal of Korean Society of Transportation
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• v.23 no.5 s.83
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• pp.177-185
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• 2005

The accuracy of a video image detector(VID) is gradually reduced due to the various environmental and mechanical factors. But there has been no systematic research about this VID accuracy decreasing. To maintain a proper level of VID accuracy for the advanced traffic management. a regular VID calibration process needs to be introduced. Because of its cost, however. the calibration cannot be performed frequently. Therefore, the method to decide the optimal calibration interval should be studied in details. This study presents two different calibration interval decision methods. Using the invented data collection equipment. some data in the field were collected and analyzed. which were used for the adaptability checking. Although the data were limited. the result is pretty promising. More data needs to be investigated later and this study will help to maintain the data quality of the ITS center.

• International Journal of Highway Engineering
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• v.15 no.3
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• pp.127-135
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• 2013

PURPOSES : The purpose of this study is development of automatic equipment to measure the road water-reservoir which can be one of factors for road traffic safety inspection and its application to safety analysis. METHODS : The scopes of this study are the examination of the riskiness and location of road water-reservoir through literature review, development of appropriate sensor and automatic equipment to survey the road water-reservoir and evaluation of field application. RESULTS: The laser lighting and IR camera were selected to develop the equipment. It was found from the field calibration that there is a high correlation between rutting and road water-reservoir and road water-reservoir caused by rutting can be correctly calculated. About 20.2km of national highway were inspected for case study and field application. It was found from correlation of traffic incident that 2.08km of the latent length for water-reservoir which is related to 12 traffic incidents were analyzed. CONCLUSIONS : This technique can be utilized evaluation method for road condition such as road water-reservoir for conventional evaluation system such as road traffic safety assessment and safety analysis and it can be use to new evaluation system to apply various road condition and traffic condition.

• Proceedings of the KOR-KST Conference
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• 2007.11a
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• pp.996-1003
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• 2007

• Journal of Korean Society of Transportation
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• v.29 no.1
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• pp.113-123
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• 2011

The application of micro-simulation model has been extended farther with improvement of computer performance and development of complicated model. To make a micro-simulation model accurately replicate field traffic conditions, model calibration is very crucial. Studies on calibration of micro-simulation model have not been enough while lots of studies on calibration of macro-simulation model have been continued in our country. This paper presents an auto-calibration of parameter values in micro-simulation model(VISSIM) using genetic algorithm. RMSE(Root Mean Square Error) of collected volume on the urban expressway versus simulated volume is set as MOP(measure of performance) and objective function of optimization is set as to minimize the RMSE. Applying to urban expressway(Nae-bu circular) as a case study, it shows that RMSE of optimized parameter values decrease 60.4%($19.3{\longrightarrow}7.6$) compared to default parameter values and the proposed auto-calibration system is very effective.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.2
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• pp.29-43
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• 2019

The calibration of microscopic traffic simulation models has received much attention in the simulation field. Although no standard has been established for it, a genetic algorithm (GA) has been widely employed in recent literature because of its high efficiency to find solutions in such optimization problems. However, the performance still falls short in simulation analyses to support fast decision making. This paper proposes a new calibration procedure using a dual GA and central composite design (CCD) in order to improve the efficiency. The calibration exercise goes through three major sequential steps: (1) experimental design using CCD for a quadratic response surface model (RSM) estimation, (2) 1st GA procedure using the RSM with CCD to find a near-optimal initial population for a next step, and (3) 2nd GA procedure to find a final solution. The proposed method was applied in calibrating the Gipps car-following model with respect to maximizing the likelihood of a spacing distribution between a lead and following vehicle. In order to evaluate the performance of the proposed method, a conventional calibration approach using a single GA was compared under both simulated and real vehicle trajectory data. It was found that the proposed approach enhances the optimization speed by starting to search from an initial population that is closer to the optimum than that of the other approach. This result implies the proposed approach has benefits for a large-scale traffic network simulation analysis. This method can be extended to other optimization tasks using GA in transportation studies.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1D
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• pp.13-16
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• 2006

Recently, ITS has been deployed nationwide and at the same time, the demand for the better accuracy and higher quality of traffic information has been increased. Yet, there is no standard evaluation methods or evaluation equipments to verify ITS device's performance, being unable to secure reliable traffic data. In this study, the standard evaluation methods for ITS device's performance are studied by reviewing other nations' evaluation methods and the evaluation system is developed.

• Journal of Korean Society of Transportation
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• v.14 no.2
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• pp.119-136
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• 1996

The evaluation of risk level or possibility of traffic accidents is a fundamental task in reducing the dangers associated with current transportation system. However, due to the lack of data and basic researches for identifying such factors, evaluations so far have been undertaken by only the experts who can use their judgements well in this regard. Here comes the motivation this thesis to evaluate such risk level more or less in an automatic manner. The purpose of this thesis is to test the fuzzy-logic theory in evaluating the risk level of traffic accidents. In modeling the process of expert's logical inference of risk level determination, only the geometric features have been considered for the simplicity of the modeling. They are the visibility of road surface, horizontal alignment, vertical grade, diverging point, and the location of pedestrain crossing. At the same time, among some inference methods, fuzzy composition inference method has been employed as a back-bone inference mechanism. In calibration, the proposed model used four sites' data. After that, using calibrated model, six sites' risk levels have been identified. The results of the six sites' outcomes were quite similar to those of real world other than some errors caused by the enforcement of the model's output. But it seems that this kind of errors can be overcome in the future if some other factors such as driver characteristics, traffic environment, and traffic control conditions have been considered. Futhermore, the application of site's specific time series data would produce better results.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.1-13
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• 2021

In this study, a time series analysis technique was applied to calibrate and predict traffic data for various purposes, such as planning, design, maintenance, and research. Existing algorithms have limitations in application to data such as traffic data because they show strong periodicity and seasonality or irregular data. To overcome and supplement these limitations, we applied the SARIMA model, an analytical technique that combines the autocorrelation model, the Seasonal Auto Regressive(SAR), and the seasonal Moving Average(SMA). According to the analysis, traffic volume prediction using the SARIMA(4,1,3)(4,0,3) 12 model, which is the optimal parameter combination, showed excellent performance of 85% on average. In addition to traffic data, this study is considered to be of great value in that it can contribute significantly to traffic correction and forecast improvement in the event of missing traffic data, and is also applicable to a variety of time series data recently collected.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.829-834
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• 2008

Augmented reality makes the relationship between real world and virtual world. The basic goal of an AR system is to enhance the user's perception of and interaction with the real world through supplementing the real world with 3D virtual objects that appear to coexist in the same space as the real world. ARToolkit is widely used toolkit to develop any AR application. However, to do so, a lot of researcher faced many challenges and limitations. In this paper we comprehensively review some selected challenging issues using ARToolkit to develop AR system. And then, we implement a real application for augmented text book with sounds and 3D virtual objects which we called here AR Traffic Book concerning these challenging issues by ARToolkit. In this paper our foremost approaches on the most common challenging issues such as virtual object rendering, camera calibration and tracking.