• Journal of the Korean Society for Railway
• /
• v.17 no.4
• /
• pp.281-288
• /
• 2014

The objective of this study was to estimate the vibration reduction capacities of a floating track system using a resilient rubber mat, and to compare the results with the track support stiffness and track impact factor of a conventional slab track system by performing field tests using actual vehicles running along a service line. The theoretically designed track support stiffness and track impact factor were compared with the measured track support stiffness and track impact factor for each tested track. The calculated and measured track support stiffness of the floating track system were found to be similar, and the floating track system satisfied the design specifications of the track impact factor. The overall vibration level and track support stiffness of the floating track system were thereupon found to be significantly lower than those of the conventional slab track system. The experimental results thus showed that the vibration reduction effect of the floating track system is greater than that of the conventional slab track.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1071-1076
• /
• 2007

In high-speed line, at some part of the track which rubber ballast-mat installed, track irregularity grew rapidly and affected riding comfort and train running stability. It is urgently requested to establish counter-measures which can be applied to track under operation. To do this, it is very important to analysis the origin of that phenomenon before. Track support stiffness is an essential factor for evaluating track condition. Sudden changes of support stiffness along track occur instability of train and bad riding comfort. Preventing sudden changes of track support stiffness is a key technique in high-speed track maintenance. Besides the sudden changes, the magnitude itself also significantly affects track and train. Low stiffness of ballast-mat makes ballast acceleration area wider. And it may accelerate track irregularity growth. So, the stiffness should be limited. To calculate track stiffness, measuring load and displacement on track is needed. In this study, the behavior of the track which rubber ballast-mat installed was measured and analyzed to understand the origin of rapid growth of it.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1115-1120
• /
• 2007

Recently, the development of the paved track is required as a low-maintenance of conventional line. The main reason is that the line capacity and bearing of track are increased progressively. The important factors of paved track are stability and applicability. To be based on this subject, Cement Mortar Pouring(CMP) paved track is developed. CMP paved track is a kind of ballast reinforced track using the prepacked concrete technique. The most important thing to design the paved track is to optimize the track structure considering various conditions. In this study, the CMP track is constructed(30m) on a test line and the track performance tested by running train to evaluation the capability and workability. The track performance are tested to confirm the vibration acceleration of the car body, wheel and track, accumulated settlement, track irregularity and crack of surface.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.311-319
• /
• 2011

Track accompanies the process that track alignment by traffic loads is changed. A change of track alignment affects the running safety and riding comfort of train. This is called a track irregularity. The most important task in maintaining the track is to manage these track irregularity within quality parameters. Today, track maintenance of urban transit is enforcing immediate maintenance about section exceeding a safety standard by applying track recording data got through Integrated Measurement. This method is advantage of being easy of the maintenance assesment in case of the running safety, but is disadvantage of being difficult in case of the riding comfort of train. In this study, we propose track irregularity deviation of each track system depending on the time series and present about utilization plans of the Track Irregularity Progress Rate.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.7
• /
• pp.683-687
• /
• 2009

Track jump control is a random access strategy for short distance movement. The most common track jump scheme is a bang-bang control of a kick and brake manner. In a conventional track jump scheme, a track-following compensator is turned off during kick and brake periods, and restarted at a target track for track pull-in. The inevitable controller switching with non-zero initial condition results in undesirable transient response, and excessive overshoot in the transient response causes track pull-in failure. In this paper, a new track jump scheme is proposed for enhancing track jump stability. Instead of control switching, internal states of a track-following controller are artificially manipulated for kick and brake actions in a digital control environment. Experimental results are provided in comparison with conventional track jumps.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.249-255
• /
• 2010

Ballasted track is under the circumstance of repetition of deterioration and recovery. Track deterioration is presented as track irregularity or settlement, and dynamic force subjected to track is one of major cause of the deterioration. The dynamic force is determined from the dynamic interaction between track and vehicle. Rail-pad stiffness is one of the factor affects track dynamic property. In this study, the relationship between rail-pad stiffness and track settlement was investigated. Dynamic forces according to various rail-pad stiffness was obtained from the dynamic vehicle-track interaction analysis using DARTS-NL. Track settlement was calculated by substitution the dynamic forces into various formulas for track settlement. From the result of analysis, it was known that the track settlement is increased about 6% when the rail-pad stiffness rise about twice. And this result leads that there is only a little relationship between rail-pad stiffness and track settlement.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.66-72
• /
• 2009

In order to forecast the progress of the track irregularity, we should observe the long-term track quality and divide a track into some separated divisions which have homogeneous property. For this, we define the division of track which has homogeneous property as a 'Segment' and manage the 'TQI(Track Quality Index)' using track induction data based on each segment. In this study, we introduce some methods of estimating track quality and figure out the TQIs of sample section using new FRA TQI method. In addition, we conducted a basic study of the forecasting model for the progress of track irregularity by analyzing track maintenance data.

• Structural Engineering and Mechanics
• /
• v.66 no.1
• /
• pp.15-25
• /
• 2018

Post-construction subgrade settlement especially differential settlement, has become a key issue in construction and operation of non-ballasted track on high-speed railway soil subgrade, which may also affect the dynamic performance of passing trains. To estimate the effect of differential subgrade settlement on the mechanical behaviors of the vehicle-slab track system, a detailed model considering nonlinear subgrade support and initial track state due to track self-weight is developed. Accordingly, analysis aiming at a typical high-speed vehicle coupled with a deteriorated slab track owing to differential subgrade settlement is carried out, in terms of two aspects: (i) determination of an initial mapping relationship between subgrade settlement and track deflections as well as contact state between track and subgrade based on a semi-analytical method; (ii) simulation of dynamic performance of the coupled system by employing a time integration approach. The investigation indicates that subgrade settlement results in additional track irregularity, and locally, the contact between the concrete track and the soil subgrade is prone to failure. Moreover, wheel-rail interaction is significantly exacerbated by the track degradation and abnormal responses occur as a result of the unsupported areas. Distributions of interlaminar contact forces in track system vary dramatically due to the combined effect of track deterioration and dynamic load. These may not only intensify the dynamic responses of the coupled system, but also have impacts on the long-term behavior of the track components.

• Journal of the Korean Society of Safety
• /
• v.33 no.2
• /
• pp.152-157
• /
• 2018

The degradation and damage of the components for ballasted track could be caused a serious problem for railway safety. Therefore, the integrity evaluation of ballasted track condition is important to ensure and predict that the track safety and track maintenance. Various track components such as rail pad, ballast, sleeper, and rail that are widely used in Republic of Korea and represent a range of physical properties have been selected for this research. In this study, the experimental modal analysis was performed by the non-destructive testing. Modal test results were obtained from the field test and used to assess the condition of the track components. From the field test, the system of ballasted track was found to be simplified as a two-degree-of-freedom(2DOF) dynamic system. The condition of track component was found to directly affect the dynamic response of ballasted tracks. As the results, the dynamic properties of the track component was depend on the track condition and was distributed more roughly and over a wider range than its initial design values. Further, the methodology presented in this study is possible to determine experimentally the fundamental track parameters which are required in the numerical analysis, and also are useful for the safety assessment of track condition.

• Smart Media Journal
• /
• v.13 no.5
• /
• pp.9-18
• /
• 2024

Multi-Object trajectory modeling is a major challenge in MOT. CenterTrack tried to solve this problem with a Heatmap-based method that tracks the object center position. However, it showed limited performance when tracking objects with complex movements and nonlinearities. Considering the degradation factor of CenterTrack as the dynamic movement of pedestrians, we integrated the EKF into CenterTrack. To demonstrate the superiority of our proposed method, we applied the existing KF and UKF to CenterTrack and compared and evaluated it on various datasets. The experimental results confirmed that when EKF was integrated into CenterTrack, it achieved 73.7% MOTA, making it the most suitable filter for CenterTrack.