• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1024-1028
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• 2008

The ballast, one of track components, plays an essential role as intermedium in transmitting train load to subgrade safely, and the deterioration of ballast directly effects the growth of track irregularity. In this study, we determined the main factor of ballast deterioration was miniature of ballast gravel caused MTT(Multiple Tie Tamper) works and accumulated traffic loads. To estimate the deterioration characteristics of ballast, we carried out field test through track construction for test and the model test simulating the actual operation environment, have done a comparative analysis with the sample's result(crushing rate) of high-speed railroad running actually.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.793-799
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• 2011

A comprehensive analysis of wheel force spectrum is conducted to provide the KTX safety evaluation with structural behaviour of Pre-Stressed Concrete (PSC) box bridge due to various high speeds. The wheel spectrum for KTX locomotive running over road and PSC bridge tracks is compared using irregular track responses with numerical models of 170m approach road track and 40m span length of PSC box bridge The high-speed railway locomotive is used as 38-degree of freedom system. Three displacements (vertical, lateral, and longitudinal) and three rotational components (pitching, rolling, and yawing) for one car-body and two bogies are considered in the 38-degree of freedom model. Three dimensional frame element of finite element method (FEM) is used to model of the simply supported PSC box bridge. The irregulation of rail-way is derived using the experiential spectrum density function under assumption of twelve level tracks conditions based on the normal probability procedure. The dynamic analyses by Runge-Kutta method which are able to analyze the high frequency wheel force spectrum. A dynamic behaviour of KTX due to high speeds until 450km/h developing speed with relative time is analysed and compared the characteristics running over the road and PSC box bridge tracks. Finally, the KTX integrated evaluation method of safety between high speed train and bridge is presented.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1121-1128
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• 2007

Subway routes $1{\sim}4$ were constructed in gravel roadbed track structure in consideration of the technological capabilities, construction cost and duration at the time of the initial construction. As such, 224.8km, approximately 81.2% of entire length, of total length of railway track at 276.9km was constructed on gravel roadbed. However, improvement of gravel roadbed to concreted roadbed began in 1998 due to problems including frequent repair works and limited time application for such works caused by occurrence of tract distortion during operation as well as lowering of roadbed functions and generation of dust caused by frictional power, impact absorption capabilities, abrasion and crushing of gravel on roadbed. Currently, this improvement is continuing with target of converting entire route into concreted roadbed structure. Therefore, this Study modifies formula for setting cant, analyze the correlation between wearing of rail side of the curvature and cant insufficiency following increasing of the running speed of the train, and to present the directions for fundamental review for adjustment of cant insufficiencies at the time of improvement of gravel roadbed to concreted roadbed that is being implemented on the operational tracks of the railway trains.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.529-544
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• 2007

After rapid running is begun in domestic, problem by the train gust that was not considered at existent train running appeared. If the High-Speed railway business speed rises by 350km/h in the future, is going to become more big problem. This study conducts an experiment that measure in local about KTX train beside Gyeong-Bu High speed railroad track about aerodynamics effect that happen by passage of train and analyzed. In case KTX II runs with the 350km/h speed, forecasted effect that get in the simple vertical surfaces parallel to tracks according to distance from rail center. Compared construction size with structural analysis in case do not consider with case that consider the train gust about sound proof walls representatively. As a result, proposed wind load standard that apply at sound proof walls design.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.151-157
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• 2008

Subway routes $1\sim4$ were constructed in gravel roadbed track structure in consideration of the technological capabilities, construction cost and duration at the time of the initial construction. As such, 224.8km, approximately 81.2% of entire length, of total length of railway track at 276.9km was constructed on gravel roadbed. However, improvement of gravel roadbed to concreted roadbed began in 1998 due to problems including frequent repair works and limited time application for such works caused by occurrence of tract distortion during operation as well as lowering of roadbed functions and generation of dust caused by frictional power, impact absorption capabilities, abrasion and crushing of gravel on roadbed. Currently, this improvement is continuing with target of converting entire route into concreted roadbed structure. Therefore, this Study modifies formula for setting cant, analyze the correlation between wearing of rail side of the curvature and cant insufficiency following increasing of the running speed of the train, and to present the directions for fundamental review for adjustment of cant insufficiencies at the time of improvement of gravel roadbed to concreted roadbed that is being implemented on the operational tracks of the railway trains.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.562-568
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• 2011

Superimposition of horizontal and vertical curves occurs frequently owing to geographical conditions. It may hamper train ride comfort and running safety and inflate maintenance costs. In this study, when the horizontal and vertical curves are superimposed, in order to analyze the effects of the compensation cant, the analytical study for running safety, ride comfort and track forces was performed in high speed line. From the analysis results, it was found that it is better to apply the compensation cant at superimposition part.

• Advances in Computational Design
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• v.8 no.1
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• pp.1-12
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• 2023

To consider the effects of the increasing speed of next-generation high-speed trains, the existing traffic safety code for railway bridges needs to be improved. This study suggests a numerical method of evaluating the new effects of this increasing speed on railway bridges. A prestressed concrete (PSC) box bridge with a 40 m span length on the Gyeongbu track sector is selected as a representative example of high-speed railway bridges in Korea. Numerical models considering the inertial mass forces of a 38-degree-of-freedom train and the interaction forces with the bridge as well as track irregularities are presented in detail. The vertical deflections and accelerations of the deck are calculated and compared to find the new effects on the bridge arising with increasing speed under simply and continuously supported boundary conditions. The ratios between the static and dynamic responses are calculated as the dynamic amplification factors (DAFs) under different running speeds to evaluate the traffic safety. The maximum deflection and acceleration caused by the running speed are indicated, and regression equations for predicting these quantities based on the speed are also proposed.

• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.115-124
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• 2006

This study was conducted to investigate the running motion in the max-velocity phase(150-160m) and the fatigue phase(350-360m) during 400m sprint by performed elementary school athletes. Eighteen elementary school male athletes who achieved at least the 3rd place in the sprint at the Korea Gangwon-Do elementary school track and field meetings during 2004 and 2005 were selected as subjects. The running motions performed by the subjects were recorded using two 8mm high speed cameras at the nominal speed of 100 frames per second. The Direct Linear Transformation technique was adopted from the beginning of filming to the final stage of data extraction. KWON 3D motion analysis package program was used to compute the 3 Dimensional coordinates, smoothing factor in which lowpass filtering method was used and cutoff frequency was 6.0 Hz. The movement patterns during foot touchdown and takeoff for the running stride were related with the biomechanical consideration. Within the limitations of this study it is concluded: In order to increase running velocity, several conditions must be fullfilled at the instant of leg touchdown and takeoff during the fatigue phase(350-360m). First, the body C.O.G(Center of Gravity) height should be raised at the instant of leg touchdown and takeoff during the fatigue phase. Second, the foot contact time should be shortened and the takeoff distance should be increased at the foot takeoff during the fatigue phase. Third, the shank angular velocity with respect to a transverse axis through the center of gravity should be increased during the leg touchdown and takeoff in the fatigue phase. Forth, the active landing style described as clawing the ground with the sole of the foot should be performed during the leg touchdown and takeoff in the fatigue phase) phase. Fifth, In order to increase running velocity in the fatigue phase while taking a slightly greater leg knee angle and body lean angle within the range of the subject's running motion during the fatigue phase would result in greater flight distance.

• Journal of the Korean Geotechnical Society
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• v.31 no.9
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• pp.29-38
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• 2015

In this study, track dynamic interaction characteristics caused by the vehicle running through transitional section such as bridge abutments were studied using the finite element analysis program. The geometric condition of track was generated by trigonometric function and allowable maximum track irregularity is determined by KORAIL track maintenance criteria. The sub-infrastructure under rail fastener system was modelled by 3D solid elements. To reduce computational cost only half track line is numerically considered and the roller boundary condition was applied to each side of model. In this study, the vehicle-track dynamic interaction analysis was carried out for standard Korean transition section of concrete track and the dynamic behaviors were investigated. The dynamic characteristics considered are wheel load variation, vertical acceleration at body, and maximum Mises stress at each part of transitional section.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.11
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• pp.1437-1443
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• 2013

Railways are currently subject to the enforcement of speed limits for each curve as prescribed by the Railway Operating Rules in Korea. However, research is required to determine the maximum speed of trains passing through each curve that allows them to run without the risk of derailment in relation to the speed enhancement of existing railway tracks. In addition, factors affecting the running safety of railway vehicles can be classified into those in terms of vehicle aspects and those in terms of track aspects. This study sought to analyze the running safety of railway vehicles according to changes in the inclination of the rail from among the factors affecting the enhancement of safety against derailment. To increase the speed of trains passing through curves that have high derailment risk, this study also analyzed the running safety of railway vehicles according to the inclination of the rail and changes in running speed while a vehicle passes through each curve section in both the up and the down train line sections between Namsunghyun and Chungdo, which represent the actual conditions of railway tracks.