• Journal of the Korean Society of Safety
• /
• v.32 no.3
• /
• pp.123-129
• /
• 2017

This study deals with the traffic accident of truck at circular intersection. The purpose of this study is to develop the truck accident models based on type of accident and conflict. In pursuing the above, the study gives particular attentions to selecting the appropriate models among Poisson and Negative binomial models using statistical program LIMDEP 8.0. The traffic accident data from 2007 to 2014 are collected from TAAS data set of Road Traffic Authority. Such the dependent variable as number of truck accidents and the 24 independent variables as geometry, traffic volume and others are used. The main results are as follows. First, 5 Poisson models (${\rho}^2$ of 0.164~0.351) which are all statistically significant are selected. Second, the common variable based on type of accident and conflict is analyzed to be truck apron width. The specific variables are, however, evaluated to splitter island, area of splitter island, speed limit sign, truck apron, number approach road, circular intersection sign, speed hump and traffic volume. Finally, widening the truck apron width and improving the above specific variables are analyzed to be important for truck accident reduction at circular intersections.

• International Journal of Highway Engineering
• /
• v.20 no.2
• /
• pp.67-74
• /
• 2018

PURPOSES : The goal of this study is the development of roundabout accident models for urban and non-urban areas. METHODS : This study performed a comparative analysis of the regional factors affecting accidents. Traffic accident data were collected for the period 2010~2014 from the TAAS data set of the Road Traffic Authority. To develop the roundabout accident models, the Poisson and negative binomial regression models were used. A total of 25 explanatory variables such as geometry, and traffic volume were used. RESULTS : The key findings are as follows: First, it was found that the null hypotheses that the number of accidents is the same should be rejected. Second, three Poisson regression accident models, which are statistically significant (${\rho}^2$ of 0.154 and 0.385) were developed. Third, it was noted that although the common variable of the three models (models I~III) is the number of entry lanes, the specific variables are entry lane width, roundabout sign, number of circulatory roadways, splitter island, number of exit lanes, exit lane width, number of approach roads, and truck apron. CONCLUSIONS : The results of this study can provide suggestive countermeasures for decreasing the number of roundabout accidents.

• International Journal of Highway Engineering
• /
• v.20 no.2
• /
• pp.119-126
• /
• 2018

PURPOSES : The purpose of this study is to develop a crash prediction model at signalized intersections, which can capture the randomness and uncertainty of traffic accident forecasting in order to provide more precise results. METHODS : The authors propose a random parameter (RP) approach to overcome the limitation of the Count model that cannot consider the heterogeneity of the assigned locations or road sections. For the model's development, 55 intersections located in the Daejeon metropolitan area were selected as the scope of the study, and panel data such as the number of crashes, traffic volume, and intersection geometry at each intersection were collected for the analysis. RESULTS : Based on the results of the RP negative binomial crash prediction model developed in this study, it was found that the independent variables such as the log form of average annual traffic volume, presence or absence of left-turn lanes on major roads, presence or absence of right-turn lanes on minor roads, and the number of crosswalks were statistically significant random parameters, and this showed that the variables have a heterogeneous influence on individual intersections. CONCLUSIONS : It was found that the RP model had a better fit to the data than the fixed parameters (FP) model since the RP model reflects the heterogeneity of the individual observations and captures the inconsistent and biased effects.

• The Journal of the Acoustical Society of Korea
• /
• v.14 no.2
• /
• pp.80-91
• /
• 1995

A theoretical models has been prepared which describes the noise generated by tire/road interaction for the tire structure-borne sound analysis. The model begin with a set of thin shell equations describing the motion of the belt of a radial ply tire, as drived by Bohm('mechanisms of the belted tire', Igeniur-Archiv, XXXV, 1966). Structural quantities required for these equations are derived from material properties of the tire. The rolling shape of a tire is computed from the steady-state limit of these equations. Vibrational response of the tire is treated by the full dependent shell equations. The force input at the tire/road interface is calculated on the basis of tread geometry and distribution of contact patch pressure. Radiation of noise is calculated by a simpson integral. Using the programs, the effect on noise of various tire design variations is computed and discussed. Trends which lead to quiet tire design are identified.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2002.11a
• /
• pp.163-170
• /
• 2002

Terrain surfaces have to be modeled in very detail and wheel-surface contacting geometry must be well defined in order to obtain proper ground-reaction and friction forces for realistic simulation of off-road vehicles. Delaunay triangulation is one of the most widely used methods in modeling 3-dimensional terrain surfaces, and T-search is a relevant algorithm for searching resulting triangular polygons. The T-search method searches polygons in successive order and may not allow real-time computation of off-road vehicle dynamics if the terrain is modeled with many polygons, depending on the computer performance used in the simulation. In order to accelerate the searching speed of T-search, a terrain database of triangular polygons is modeled in multi-levels by adopting the LOD (Level of Detail) method used in realtime computer graphics. Simulation results show that the new LOD search is effective in shortening the required computing time. The LOD search can be even further accelerated by introducing an NN (Neural Network) algorithm, in the cases where a appropriate range of moving paths can be predicted by cultual information of the simulated terrain, such as lakes, houses, etc.. Numerical tests show that LOD-NN search almost double the speed of the original T-search.

• Journal of the Korean Society of Safety
• /
• v.32 no.5
• /
• pp.135-140
• /
• 2017

This study deals with the safety of roundabout. The purpose of this study is to analyze the factors affecting the pedestrian accidents of roundabout near schools. In pursuing the above, this study gives particular attentions to comparatively analyzing the pedestrian accident by number of entry and circulatory lane. The traffic accident data from 2013 to 2015 are collected from TAAS data set of Road Traffic Authority. To develop the pedestrian accident model, the Poisson and negative binomial models has been utilized in this study. Such the dependent variable as the number of pedestrian accidents and the 24 independent variables as geometry, traffic volume and others are used. The main results are as follows. First, 3 Poisson and 2 negative binomial models(${\rho}^2$ of 0.153~0.426) which are all statistically significant are developed. Second, the common variable of models based on the number of circulatory roadway lane is analyzed to be the entry lane width and that of the number of entry lane is evaluated to be the design speed. Also specific variables are evaluated to splitter island, roundabout sign, number of approach road, bus stop and elementary school. Finally, the design speed might be expected to decrease the number of pedestrian accidents near schools.

• Proceedings of the KSRS Conference
• /
• 2007.10a
• /
• pp.625-628
• /
• 2007

We present an efficient and robust technique to estimate the velocity of moving targets from a single SAR image. In SAR images, azimuth image shift is a well known phenomenon, which is observed in moving targets having slant-range velocity. Most methods estimated the velocity of moving targets from the distance difference between the road and moving targets or between ship and the ship wake. However, the methods could not be always applied to moving targets because it is difficult to find the road and the ship wake. We adopted a method estimating the velocity of moving targets from azimuth differentials of range-compressed image. This method is based on an assumption that Doppler center frequency shift of moving target causes a phase difference in azimuth differential values. The phase difference is linearly distorted by Doppler rate due to the geometry of SAR image. The linear distortion is eliminated from phase removal procedure, and the constant phase difference is estimated. Finally, range velocity estimates for moving targets are retrieved. This technique is tested using an ENVISAT ASAR image in which several unknown ships are presented. The theoretical accuracy of this technique is discussed by SAR simulation. The advantages and disadvantages of this method over the conventional method are also discussed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.5
• /
• pp.125-133
• /
• 2011

The wear of rubber track being in contact with the road surface is an important subject because it decreases the traction performance and the operating efficiency of tracked vehicle. For the above reasons, many attempts have been made to quantitatively calculate the rubber track. However, it depends on the experimental methods which are highly time- and cost-consuming. Therefore, the numerical simulation approach is highly desirable, but it needs to model the complex geometry and the material behavior in details as well as the interaction with the road surface. In this study, the rubber track and its material behavior are elaborately modeled since these factors are very important in the prediction of the wear rate of the rubber track. Accordingly to the studies on the rubber wear by previous investigations, it has been found that the wear is greatly influenced by the frictional energy. The frictional energy of rubber track is computed by utilizing the 3D finite element analysis of the rubber track, and the wear rate is evaluated making use of the frictional energy and a wear model.

• Journal of the Korean Society of Combustion
• /
• v.21 no.2
• /
• pp.1-6
• /
• 2016

To meet the Tier-4 emission standard, a variety of combustion technology in the field of off-road engine has been applied in conjunction with the engine after treatment technology. In this study, as the basis study for applying VGT and HPL EGR to 3.6 L CRDi engine, exhaust gas characteristics and fuel economy characteristics are confirmed in accordance with VGT and EGR operating conditions. Consequently, in the EGR applicable conditions, 60% VGT vane duty condition was confirmed that the trade-off characteristics between NOx and smoke are advantageous. In addition, in view of BSFC, VGT vane duty is considered desirable to control at around 50%.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.39 no.5
• /
• pp.253-263
• /
• 2021

Traffic data collected using advanced equipment are highly valuable for traffic planning and efficient road operation. However, there is a problem regarding the reliability of the analysis results due to equipment defects, errors in the data aggregation process, and missing data. Unlike other detectors installed for each vehicle lane, radar detectors can yield different error types because they detect all traffic volume in multilane two-way roads via a single installation external to the roadway. For the traffic data of a radar detector to be representative of reliable data, the error factors of the radar detector must be analyzed. This study presents a field survey of variables that may cause errors in traffic volume collection by targeting the points where radar detectors are installed. Video traffic data are used to determine the errors in traffic measured by a radar detector. This study establishes three types of radar detector traffic errors, i.e., artificial, mechanical, and complex errors. Among these types, it is difficult to determine the cause of the errors due to several complex factors. To solve this problem, this study developed a radar detector traffic volume error analysis model using a multiple linear regression model. The results indicate that the characteristics of the detector, road facilities, geometry, and other traffic environment factors affect errors in traffic volume detection.