• Journal of the Korean Society for Railway
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• v.6 no.4
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• pp.239-245
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• 2003

In this paper, the track impact factor of conventional line was evaluated using the data for wheel load measured in field and the properties of current operating trains. The equation for track impact factor was presented through the statistical analysis of variational ratio in wheel load and compared with other design equations in domestic and foreign countries. A review on the safety of track system in conventional line was made from the relationship between the velocity and the corresponding impact factor. It was found that the impact factor from the proposed equation is a little less than the values from the equations adopted in both AREA and domestic railway, while it is same as the equation for continuous welded rail(CWR) in Japan. Therefore it could be said that the track satisfies a criteria for dynamic load caused by the train and the corresponding level of safety is guaranteed for dynamic load of the train

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.954-959
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• 2011

The intensity of train load in the railway bridges is relatively large and continues to repeat. Also, the speed of vehicles is very fast. For these reasons, analyses for dynamic response under train load are necessary in the railway bridges. In other words, the dynamic characteristics of steel-composite bridges under train loads should be investigated considering effects of dynamic responses such as vibrations, repeated displacements and acceleration of bridge members. Therefore, in this study, static and dynamic analyses for the steel box girder bridges and I-girder bridges are carried out. Based on analyses results, we investigated and compared dynamic response considering the impact factors of domestic and foreign design specifications.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.82-87
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• 2010

A measurement system of contact force between overhead contact line and pantograph of train is developed which measures the contact force by using four sets of full-bridge strain gauges instead of load cells and accelerometers. The sensors are installed on the pan head of pantograph and the measured data from the sensors are transmitted to a server system in the train by way of wireless Lan. This configuration of the measuring system makes it easy to install on the trains without any alteration of train system. The measurement system is applied to KTX on the Kyungbu high speed line, and the measured contact force data shows good agreement with those measured by load cell and accelerometers. The waveform of the contact force between overhead contact line and pantograph contains essential information about their conditions. The proposed measurement system can probe any defects on overhead contact lines with train running at high speed, which will be a powerful solution for the maintenance of long-distance overhead contact lines.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1739-1747
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• 2001

Experimental study has been conducted to clarify the pneumatic characteristics of brake system for freight train and enhance the performance of diaphragm valve. Empty-load and diaphragm valves are installed in pneumatic brake system for freight trains of KNR (Korean National Railroad). Experiments are conducted by using freight train and diesel locomotive in operation. From the experimental results. new quick release valve shortens release time after brake application. In case of normal brake application, the release time is shortened to 34% of the original diaphragm valve. Reducing the release time of pneumatic brake system will be helpful to assure brake-release application and save maintenance efforts like wheel grinding.

• Structural Engineering and Mechanics
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• v.51 no.4
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• pp.581-599
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• 2014

In this paper the overall dynamic response of simple railway bridges subjected to high-speed trains is investigated numerically based on the mechanical models of simply supported single-span and continuous two-span Bernoulli-Euler beams. Each axle of the train, which is composed of rail cars and passenger cars, is considered as moving concentrated load. Distance, magnitude, and maximum speed of the moving loads are adjusted to real high-speed trains and to load models according to Eurocode 1. Non-dimensional characteristic parameters of the train-bridge interaction system are identified. These parameters permit a spectral representation of the dynamic peak response. Response spectra assist the practicing engineers in evaluating the expected dynamic peak response in the design process of railway bridges without performing time-consuming time history analyses.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.964-972
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• 2008

In the retaining wall design process, track and train loads are usually considered as uniform surcharge loads and strip loads. In this paper, the lateral(horizontal) earth pressure on retaining structures caused by track and train load are calculated using the Boussinesq solution. And also total horizontal force per unit length and the location of the resultant force were estimated with the changes of loading locations and widths of the loadings. The maximum horizontal earth pressure and the location of it for high-speed train load were 11.83kPa and 1.7m at the loading condition 2m away from retaining walls.

• Steel and Composite Structures
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• v.31 no.5
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• pp.437-452
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• 2019

In this study, in-situ static and dynamic tests of four pre-stressed concrete (PC) track beams with different span lengths and curvatures in a straddle monorail transit system were reported. In the static load tests, the strain and deflection at critical sections of the PC track beams were measured to determine the load bearing capacity and stiffness. The dynamic responses of strain, deflection, acceleration, and displacement at key positions of the PC track beams were measured under different train speeds and train loads to systematically study the dynamic behaviors of the PC track beams. A three-dimensional finite element model of the track beam-vehicle coupled vibration system was established to help understand the dynamic behavior of the system, and the model was verified using the test results. The research results show that the curvature, span length, train speed, and train loads have significant influence on the dynamic responses of the PC track beams. The dynamic performance of the PC track beams in the curve section is susceptible to dynamic loads. Appropriate train loads can effectively reduce the impact of the train on the PC track beam. The PC track beams allow good riding comfort.

• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.39-45
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• 2023

In this paper, a track irregularity according to adjacent deep excavation of railway was analyzed using three-dimensional numerical analysis. The construction for excavation adjacent to the railway track is likely to have a negative impact on train operations. Despite mandatory assessments of the stability and impact on adjacent structures during construction, reports continue to indicate ongoing settlement and track irregularity resulting from construction. Changes in the groundwater level and stress state of the ground due to excavation are pointed out as causes for settlement and track irregularity in structures adjacent to the excavation. In this study, therefore, numerical analysis was conducted taking into account factors that induce track irregularity during adjacent excavation work as variables. The KRL-2012 standard train load was applied to simulate operating trains. As a results, The position of the train load, the distance from the excavation point, had a significant impact on track irregularity, and there was a significant occurrence of track misalignment when the train load was applied. The impact of the groundwater level was not significant.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.359-366
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• 2009

This paper aims for analyzing the vibration serviceability of train by simply expressing its vertical vibration when it passes a railway bridge. For this purpose, bridge-train transfer function was derived and bridge-train interaction analysis was performed by using the derived function. The bridge-train transfer function was developed with the assumption that train is a single mass-spring system, and bridge-train interaction analysis was performed on simple beams of KTX passenger car. The vertical acceleration signals of passenger cars obtained from bridge-train interaction analysis were compared with them of cars obtained from the bridge-train transfer function. As a result, it could be estimated to express the vertical vibration inside the passenger car required for vibration serviceability evaluation by using the vertical vibration of bridges obtained from moving load analysis. Therefore, it may be possible to evaluate the vibration serviceability of railway bridges considering bridge-train interaction effect.

• Journal of the Korean Society for Railway
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• v.17 no.6
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• pp.457-465
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• 2014

This study proposes a policy for urban railway travel demand management system in order to decrease the load factor of the Seoul metro Circle line, particularly for the segment between Sadang and Samsung stations, through analyzing the transit smart card data. We propose mixed train operations of the existing Circle line and a line that goes toward Samsung station in order to transport passengers that have two distinct groups: those with the destination of Samsung station and those with destinations after Samsung station. The introduction of a mixed train operation that encourages passengers passing through Samsung station to take a Circle line train will decrease the congested load factor by 11.3% during the morning peak hours using the mixed train operation of the Circle and Samsung lines. This policy could be an effective method to decrease the load factor and improve the comfort of rail passengers without extra investment in the railway facilities.