• Korean Journal of Agricultural Science
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• v.39 no.3
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• pp.407-412
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• 2012

Soil texture has an important influence on agriculture such as crop selection, movement of nutrient and water, soil electrical conductivity, and crop growth. Conventionally, soil texture has been determined in the laboratory using pipette and hydrometer methods requiring significant amount of time, labor, and cost. Recently, in-situ soil texture classification systems using optical diffuse reflectometry or mechanical resistance have been reported, especially for precision agriculture that needs more data than conventional agriculture. This paper is a part of overall research to develop an in-situ soil texture classification system using image processing. Issues investigated in this study were effects of sensor travel speed and light source and intensity on image quality. When travel speed of image sensor increased from 0 to 10 mm/s, travel distance and number of pixel were increased to 3.30 mm and 9.4, respectively. This travel distances were not negligible even at a speed of 2 mm/s (i.e., 0.66 mm and 1.4), and image degradation was significant. Tests for effects of illumination intensity showed that 7 to 11 Lux seemed a good condition minimizing shade and reflection. When soil water content increased, illumination intensity should be greater to compensate decrease in brightness. Results of the paper would be useful for construction, test, and application of the sensor.

• Journal of Korean Society of Transportation
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• v.22 no.4 s.75
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• pp.117-134
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• 2004

Truck traffic accounts for a substantial fraction of the traffic stream in many regions and is often the source of localized traffic congestion, potential parking and safety problems. Truck trips tend to be ignored or treated superficially in travel demand models. It reduces the effectiveness and accuracy of travel demand forecasting and may result in misguided transportation policy and project decisions. This paper presents the development of speed-flow relationships with truck impacts based on CORSIM simulation results in order to enhance travel demand model by incorporating truck trips. The traditional BPR(Bureau of Public Road) function representing the speed-flow relationships for roadway facilities is modified to specifically include the impacts of truck traffics. A number of new speed-flow functions have been developed based on CORSIM simulation results for freeways and urban arterials.

• Journal of Korean Society of Transportation
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• v.27 no.2
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• pp.57-71
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• 2009

Due to increasing interest in dispersion of traffic flows through providing traffic information, there has been much research of driver behavior and effectiveness of diversion. In this paper the authors intend to analyze how a diversion was determined and its effects through correlation analysis between diversion rates estimated by actual surveys and the traffic conditions. Through speed-flow analysis, the diversion mechanism was found. When travel speed decreased, detour volume increased. Then when the traffic volume was decreased through an increase of diversion and traffic conditions got better, the detour volume decreased again. In addition, the authors found negative correlation between the diversion rate and travel speed through correlation analysis. It shows that there were various relationships between diversion rates and traffic conditions according to congestion level and direction of traffic. Finally, it is suggested that the regression equation for calculating the diversion rate with the traffic flows, travel speed, and travel time as variables has a coefficient of determination of 38.5%. It means that traffic conditions on expressways take about 40% of driver's decision-making for diversion.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.4
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• pp.1-10
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• 2013

This study was conducted to investigate that bus information was used as an information of travel speed. To determine the travel speed on the road, bus information and the information collected from the point detector and the interval detection installed were compared. If bus information has the function of traffic information detector, can provide the travel speed information to road users. To this end, the model of recognizing the traffic patterns is necessary. This study used simple moving-average method, simple exponential smoothing method, Double moving average method, Double exponential smoothing method, ARIMA(Autoregressive integrated moving average model) as the existing methods rather than new approach methods. This study suggested the possibility to replace bus information system into other information collection system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.40-48
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• 2012

In this paper, we suggests methods for determining optimal representative value and the optimal size of historical data for reliable travel speed prediction. To evaluate the performance of the proposed method in real world environments, we did field tests at four roadway links in Seoul on Tuesday and Sunday. According to the results of applying the methods to historical data of Central Traffic Information Center, the optimal representative value were analyzed to be average and weighted average. Second, it was analyzed that 2 months data is the optimal size of historical data used for travel speed prediction.

• Journal of Welding and Joining
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• v.16 no.5
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• pp.86-92
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• 1998

High speed wire seam weldability of tin coated thin gage sheet steels was investigated. Thickness and coating weight ranges of the test materials were 0.21~0.35mm and 1.1/1.1~2.8/11.2g/$m^2$, respectively. Test results indicated that the surface roughness value, Rz decreased as increasing the coating weight. The Rz was thought to be one of the important factors to influence the optimum welding condition range, $\triangle$Q. The $\triangle$Q showed close relationship with welding conditions such as welding pressure and travel speed. Higher welding pressure widened the $\triangle$Q while higher travel speed reduced the $\triangle$Q value. Results also demonstrated that tin coating weight should be optimized based on the weldability or the serviceability after welding. At th HAZ of sheet materials with thinner coating layer, tin depleted zone was produced since molten film of the coating material on the base metal agglomerated by the surface tension, which could result in reducing the corrosion resistance of the HAZ in the service environment.

• Journal of Korean Society of Transportation
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• v.18 no.1
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• pp.47-59
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• 2000

The purpose of this study is to develop travel-time estimation model using neural networks and prediction model using neural networks and kalman-filtering technique. The data used in this study are travel speed collected from inductive loop vehicle detection systems(VDS) and travel time collected from the toll collection system (TCS) between Seoul and Osan toll Plaza on the Seoul-Pusan Expressway. Two models, one for travel-time estimation and the other for travel-time Prediction were developed. Application cases of each model were divided into two cases, so-called, a single-region and a multiple-region. because of the different characteristics of travel behavior shown on each region. For the evaluation of the travel time estimation and Prediction models, two Parameters. i.e. mode and mean were compared using five-minute interval data sets. The test results show that mode was superior to mean in representing the relationship between speed and travel time. It is, however shown that mean value gives better results in case of insufficient data. It should be noted that the estimation and the Prediction of travel times based on the VDS data have been improved by using neural networks, because the waiting time at exit toll gates can be included for the estimation of travel time based on the VDS data by considering differences between VDS and TCS travel time Patterns in the models. In conclusion, the results show that the developed models decrease estimation and prediction errors. As a result of comparing the developed model with the existing model using the observed data, the equality coefficients of the developed model was average 88% and the existing model was average 68%. Thus, the developed model was improved minimum 17% and maximum 23% rather then existing model .

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.5
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• pp.837-844
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• 2017

Generally, V/C ratio in uninterrupted traffic flow and average travel speed in interrupted traffic flow are utilized as measure of effect for assessing operational situation of roads. The set of road conditions and traffic conditions are considered to be major variables for assessing operational situation in the traffic flow. However, weather conditions such as rainfall also affect the operational situation of roads. The studies reflected by the rainy situation are conducted in the uninterrupted flow, but the related studies are insufficient in the interrupted flow. In this study, the modification factors during rainfall in the interrupted flow were suggested, and the factors could be used when calculating the average travel speed during rainfall in the interrupted flow. By utilizing the data that were investigated in the same road and traffic conditions and the different weather conditions (rainy day or clear day), the modification factors were founded on regression analysis of the travel speed during rainfall as a dependent variable. Modification factors was suggested in dividing peak time, non-peak time, and whole period. Based on this study, the modification factors can be used to complementing the average travel speed model for assessing the operational situation of urban streets during rainfall.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.5
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• pp.149-161
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• 2022

Because the speed limit affects moving speed, it is closely related to traffic accidents as well as traffic flow. The existing speed limit calculation methods consider various engineering factors such as lanes, intersection spacing, driveways, crosswalks, 85 percentile speed, land uses, and roadway geometric characteristics etc. However, it can be said that the engineering analysis is insufficient because the traffic impact analysis considering traffic volume is not carried out. In addition, only 85 percentile speed, which is the spot speed, does not reflect the characteristics of the traffic flow on the road. In this paper, the effect of the speed limit change on the moving speed and the travel speed was analyzed in detail accordinr to the variation of intersection spacing and traffic volume. And by using the results, we proposed a speed limit calculation method that maintains the same service level as before the speed limit change, thereby increasing the speed improvement effect and reducing the difference between moving speed and travel speed. In addition, a variable speed limit operation method according to the change in traffic volume was also suggested. This method is expected to be effective in terms of safety by reducing the speed difference, which affects the severity of traffic accidents, while securing the speed improvement effect, and increasing the speed limit compliance rate of drivers by operating the speed limit that reflects the speed change due to the variation of traffic volume.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.2270-2277
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• 2010

Recently the role of a railroad is emphasized as the imprortant part for growth for the low carbon green growth and the social consensus about the railroad investment is actively progressed. The various social economic value in which the travel demand change over of the environment-friendly railroad system can bring becomes with public debate as much as a discussion is not any more necessary. In this research, the influence that it recognized that the travel time improvement by the high speed rail was the most important element among many method that it can increase the railroad use efficiency in which it connects the interregional major cities and the railway travel time improvement reaches to the rate of railway and road travel time, and the environment like the carbon emission quantity was comprehensively inquired.