• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.52-64
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• 2023

This paper concentrated on estimating the travel time value of individual regional bus passengers in various in-vehicle crowding conditions. In the analysis model, the traffic-selection data of individual transportation passengers based on smart-card data were used. Variables which reflect the level of in-vehicle crowding and the variables of in-vehicle travel time that reflect the level of in-vehicle crowding were included in the model using Box-Cox transformation. The result of this paper indicates that the travel time value experienced by individual users would increase as the in-vehicle crowding level increases. The smart card data used in this paper is considered to have significant implications in terms of conducting more sophisticated and realistic qualitative research to reflect the values of variables for in-vehicle traffic hours and in-vehicle crowding levels, which previously had limitations in observation and quantification. It is expected that the effects of improvement measures for reducing congestion on regional buses can be considered quantitatively by applying the estimation results of crowding multiplier.

• Journal of Korean Society of Transportation
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• v.4 no.1
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• pp.28-40
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• 1986

Accurate subway demand estimation which is essential for better route selection can be achieved by the exact definition of the influence sphere of subway station. The influence was derived implicitly from the analysis of access time to the station for the cases of Seoul. Access time distribution was investigated by trip purposes, by age, by income, by sex, by travel distance, by kinds of thickets, by the location of station for the analysis of relationship between access time and socio-economic characteristics or urban structure. The difference of average access time between direct access trip and transfer trip which is found 8.6 minutes and 6.1 minutes respectively also investigated. The small difference implies poor transfer system of Seoul subway. 83.1% of subway users are coming from the distance of 10minutes' walk and average access time is 7.8minutes as a whole.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3160-3172
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• 1996

A search algorithm for the collision free, time optimal transport path of overhead cranes has been proposed in this paper. The map for the working environment of overhead cranes was constructed in the form of three dimensional grid. The obstacle occupied region and unoccupied region of the map has been represented using the octree model. The best-first search method with a suitable estimation function was applied to select the knot points on the collision free transport path to the octree model. The optimization technique, minimizing the travel time required for transporting objects to the goal while subjected to the dynamic constraints of the crane system, was developed to find the smooth time optimal path in the form of cubic spline functions which interpolate the selected knot points. Several simulation results showed that the selected estimation function worked effectively insearching the knot points on the collision free transport path and that the resulting transport path was time optimal path while satisfying the dynamic constraints of the crane system.

• Journal of Korea Water Resources Association
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• v.30 no.2
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• pp.97-106
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• 1997

Parameters of the Nash model were analyzed using similarity concepts for the hydrogeomorphologic and the time response characteristics, then the application of parameter estimation was performed for a basin where no data are available. The self-similarity was investigated to evaluate the similarity of hydrogeomorphologic characteristics and to derive a equation for the time of concentration. The relation between model parameters and time characteristics such as travel and lag time, were developed to obtain their properties of similarity. There were remarkable results about the assessment for basin similarity and the application to an ungaged basin in Wi stream basin.

• Journal of Korean Society of Transportation
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• v.33 no.4
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• pp.393-404
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• 2015

Gravity model has had the major problem that the model explains the characteristics of travel behavior with only deterrence factors such as travel time or cost. In modern society, travel behavior can be affected not only deterrence factors but also zonal characteristics or transportation service. Therefore, those features have to be considered to estimate the future travel demand accurately. In this regard, there are two primary aims of this study: 1. to identify the characteristics of inter-zonal travel, 2. to develop the new type of calibration method. By employing accessibility variable which can explain the manifold pattern of trip, we define the zonal travel behavior newly. Furthermore, we suggest 2-phase calibration method, since existing calibration method cannot find the optimum solution when organizing the deterrence function with the new variables. The new method proceeds with 2 steps; step 1.estimating deterrence parameter, step 2. finding balancing factors. The validation results with RMSE, E-norm, C.R show that this study model explains the inter-zonal travel pattern adequately and estimate the O/D pairs precisely than existing gravity model. Especially, the problem with estimation of short distance trip is overcomed. In conclusion, it is possible to draw the conclusion that this study suggests the possibility of improvement for trip distribution model.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.1 s.2
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• pp.85-92
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• 2003

Due to the expansion of freeway networks in Korea, drivers have more routes to choose. Traffic information on various alternative roadway sections and routes may help drivers choose the optimal route that minimizes travel time or cost. Traffic information on roadways is, therefore, invaluable in sense that individual drivers could reduce their travel time or cost by selecting optimal routes, and furthermore total travel cost of the system could be lowered. However, consensus about the price of traffic information that drivers are willing to pay is not made yet. Current price of traffic information is decided according to the price of similar information such as stock, weather and so on. To investigate the value of traffic information, a survey was conducted at freeway rest areas near Seoul Megalopolis area including Kyunggi Province. Eight hundred drivers who had travelled on freeway within a year were randomly selected. Purposive Quota Sampling was used. A price-response function, a relationship between price and sales, was obtained based on the survey, followed by sensitivity analysis

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.24-32
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• 2007

Variable message sign (VMS), which is used for providing real-time information on traffic conditions and accident occurrences, is one of the important components of intelligent transportation systems. It is essential that the scheme of VMS message phase and duration should be designed with the consideration of drivers' message reading time that will be depended on various causal factors, such as the amount of VMS messages, drivers' travel speed, and geometric conditions. However, there have been not much efforts to explore the relationships between the drivers' message reading time and the above causal factors. Driving simulator experiments were conducted to obtain drivers' message reading time with respect to the amount of VMS messages, drivers' travel speed, and different geometric conditions. Regression modeling techniques were applied to develop an estimation model for drivers' message reading time. Probabilistic outcomes of the proposed model would be greatly utilized to design proper VMS message phase and duration.

• Journal of Korean Society of Transportation
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• v.25 no.2 s.95
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• pp.121-132
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• 2007

This paper addressed the issue of a generalized cost model for transit assignment. The model composed of walk time, waiting time (including transfer waiting time), line-haul time, transfer walk time, and fare. The weights of each component were supposed to be calculated using the stated preference (SP) data, which were collected prudently in order to reflect reality. The marginal rate of substitution and wage rate were applied to calculate the weights. The results showed that the weight of walking time per in-vehicle travel time (IVTT) was 1.507, the weight of waiting time (per IVTT) was 1.749, that of transfer time (per IVTT) was 1.474, and that of fare (per IVTT) was 1.476 for trips between inner-city areas in Seoul. Weights for each component were identified as 1.871, 1.967, 1.015, and 0.857, respectively, for trips between Seoul and Gyeonggi. Statistical significance existed between two cases and each variable was also statistically significant. Transit assignment using the relative weights estimated in this study was implemented to analyze the travel index in a macroscopic and quantitative basis. The results showed that average total travel times were 30.23 minutes and 63.29 minutes and average generalized costs were 2,510 won and 3,880 won for trips between inner-city areas in Seoul and between Seoul and Gyeonggi, respectively.

• 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.

• Journal of Korean Society of Forest Science
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• v.112 no.3
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• pp.374-381
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• 2023

The travel time of flash floods along mountain streams is mainly governed by reach-average velocity, rather than by the point velocity of the locations of interest. Reach-average velocity is influenced by various factors such as stream geometry, streambed materials, and the hydraulic roughness of streams. In this study, the reach-average velocity in mountain streams was measured for storm periods using rhodamine dye tracing. The point cloud data obtained from a LiDAR survey was used to extract the average hydraulic roughness height, such as R_a, R_max, and R_z. The size distribution of the streambed materials (D₅₀, D₈₄) was also considered in the estimation of the roughness height. The field experiments revealed that the reach-average velocities had a significant relationship with flow discharges (v = 0.5499Q^0.6165 ), with an R² value of 0.77. The root mean square error in the roughness height of the R_a-based estimation (0.45) was lower than those of the other estimations (0.47-1.04). Among the parameters for roughness height estimation, the R_a -based roughness height was the most reliable and suitable for developing the reach-average velocity equation for estimating the travel time of flood waves in mountain streams.