• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.252-260
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• 2015

Ballasted track on an asphalt roadbed can be beneficial for its various effects such as (i) decreasing of roadbed thickness by dispersing train load; (ii) prevention of both strength reduction and weakening in roadbed system by preventing rainwater penetration; and (iii) reducing maintenance cost by preventing roadbed mud-pumping and frostbite. With these beneficial effects, ballasted track on asphalt roadbed has been widely used in Europe and Japan, and relevant research for applying such ballasted track on asphalt roadbed systems in Korea is ongoing. In this study, full-scale static and dynamic train load tests were performed to compare the performance of ballasted track on asphalt roadbed and ballasted track. The optimum thickness levels of asphalt and reinforced roadbeds, corresponding to the design criteria for reinforced roadbed of high-speed railway, was estimated using the FEM program ABAQUS. Test results show that the earth pressure on reinforced roadbed of ballasted track on the asphalt roadbed was relatively low compared with that of simple ballasted track. The elastic and plastic displacements of simple ballasted track on the asphalt roadbed were also lower than those of ballasted track. These test results may indicate that the use of ballasted track on asphalt roadbed is an advantageous system in view of long-term maintenance.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.41-46
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• 2017

The coefficient of derailment and the rate of wheel load reduction were used as the index of train running safety that was directly affected the train derailment safety. In aspects of track, the train running safety depends on the complex interaction between wheel and rail, and the track-vehicle conditions (i.e., the curvature, cant, track system, vehicle speed and the operation conditions, etc). In this study, the relationship between the train running safety and the track curvature and vehicle speed for direct fixation concrete tracks currently employed in Korean light rapid transit was assessed by performing field tests using actual vehicles running along the service lines. The measured dynamic wheel load, lateral wheel load and lateral displacement of rail head were measured for same train running on four tested tracks under real conditions, which included curved and tangent tracks placed on the tunnel and bridge, thus increasing the train speed by approximately maximum design speed of each test site. Therefore, the measured dynamic track response was applied to the running safety analysis in order to evaluate the coefficient of derailment, the rate of wheel load reduction and the track gauge widening at each test site, and compare with the corresponding Korean train running safety standard. As the results, the lateral track response of direct fixation concrete track appeared to increase with the decreased track curvature; therefore, it was inferred that the track curvature directly affected the train running safety.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.162-166
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• 2011

In railway, Tie supports rail and plays a role that distribute train load to the ballast. Also, Tie and ballast resist against external force and fix the track position. But, weakening resistance of ballast and tie cause vertical displacement of tie and track irregularity. For reinforcement of track stiffness and reduction of track irregularity, KORAIL has developed Multi Branch type tie(GLORY Tie) that reinforced resistance than general PCT and installed in order to test in the field. This study measured and analyzed lateral resistance of ballast, wheel load of rail, bending strain of rail foot, vertical displacement and vibration acceleration of tie in order to evaluate performance of Multi Branch type tie in the field. According to the results of test, Multi Branch tie is excellent than general tie about lateral resistance of ballast and vertical displacement of tie. And, gap of measurement value between Multi Branch type tie and general tie about wheel load of rail, bending strain of rail foot were very small.

• Journal of Sensor Science and Technology
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• v.14 no.6
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• pp.438-443
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• 2005

In this paper, we introduce the on-line test of the current collection characteristics for HSR 350x(Korea High Speed Train project) that have been performed in the Kyoung-bu high-speed line since 2002. Through the analysis of measured data during on-line test, the variation trends of contact force between pantograph and catenary according to the track conditions and driving patterns are reviewed. This study shows that the track conditions do not affect on the dynamic performance between pantograph and the driving patterns are important factors in determining the good interaction of them.

• Journal of the Korean Society of Safety
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• v.31 no.6
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• pp.45-51
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• 2016

The purpose of this study is to investigate the influence of train-induced end rotation of simple supported track girder on the performance of a direct fixation track system (DFTS) in Yeongjong grand bridge. In this study, the influences of deflection of a DFTS and track girder on dynamic rail-track girder interaction forces for the track girder ends currently employed in airport express lines were assessed by performing field tests using actual vehicles running along the service lines. Therefore, the dynamic displacement of rail and track girder and the fastener stress on the center and ends sections of DFTS were measured for two different trains (AREX and KTX) running in Yeongjong grand bridge. A three-dimensional finite element analysis (FEA) model using the time-history function based on the design wheel load was used to predict the train-induced track and track girder displacement, and the FEA and field test results were compared. The analytical results reproduced the experimental results well within about 3-7% difference in the values. Therefore, the FEA model of DFTS on track girder is considered to provide sufficiently reliable FEA results in the investigation of the behavior of DFTS. Using the analytical and experimental results, the influence of train-induced end rotation of simple supported track girder on the interaction behavior of rail and track girder installed on a simple supported track girder ends, i.e., upward displacement of rail-track girder and the fastener stress, was investigated. It was found that the train-induced end rotation effect of track girder was not significantly affected by the upward displacement of rails and the fastener stresses of track girder ends. Further, the interaction behavior of rail and track girder were similar to or less than that of the general railway bridge deck ends, nevertheless the vertical displacement of track was higher than that of conventional DFTS on the general railway bridge. From the results, the dynamic responses of the DFTS on track girder ends were not significantly affected by the safety and stability of DFTS ends.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2405-2408
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• 2011

In recent time, the cause analysis and the reduction of the track irregularity have become the most important issue in the ballasted track on the high-speed railway bridge. This is because that the frequency of the maintenance work at the bridge expansion joint zone is on the rise. The track irregularity on the railway bridge starts at the end of the bridge-deck and spreads along the bridge. Due to the dynamic vibration and the thermal expansion of the bridge, the compaction of the ballast gravel on the bridge expansion joint zone become loose and then the progress of the track irregularity result from the train-induced dynamic impact is accelerating further. Among the several options for reducing the track irregularity on the bridge expansion joint zone, the application and efficiency of the zero longitudinal restraint(ZLR) and tied sleeper are investigated in this paper. Field test construction has been conducted, then the progress of the track irregularity and the frequency of the maintenance work are analyzed before and after the filed test construction. Of the two methods, it is shown that the installation of the ZLR seems to be better than the tied sleeper.

• Journal of Korean Library and Information Science Society
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• v.40 no.4
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• pp.199-225
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• 2009

The purpose of this paper is to grow more interest and to forster research in full-texts retrieval of digitized books area through the review of Book Search Track and the analysis of research methods. First, this paper introduces the INEX tracks, the registration of INEX, the task process and the participating organizations. Second, to introduce the Book Search Track of all INEX tracks, this paper provides an overview of the test collection, the tasks, the task and submission guidelines and evaluation results of the Book Search Track's. Third, through paper review of the Book Search track that was lunched in 2007 as part of the INEX initiative, this paper presents the future research subject. This study expects that the readers are attracted by INEX tracks and full-texts retrieval of digitized books in korea.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.55-65
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• 2009

This study is objected by analyzing whether it is applied to the analysis model considering the track stiffness or not when the railway bridge is designed or reviewed for the dynamic stability. It is performed that the analysis model is verified by comparing the field test result with the analysis result. Also, The dynamic response of railway bridge through the existing analysis model is compared with the analysis model considered the track stiffness. In addition, it is performed by analyzing the model considering the stiffness of concrete track. Therefore, this study is suggested that the design of railway bridge apply to the existing analysis model considering the mass of track and the dynamic stability review of railway bridge apply to it considered the stiffness & mass of track. Also, it is suggested that the stiffness of concrete slab on the bridge must consider when it is designed or checked over the dynamic stability.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.382-399
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• 2011

Impact factor of concrete and ballast track which has been used in Korea railway was applied to equation (1+0.513V/100) from AREA. As the use of this equation, overcapacity of track design might be occurred. Therefore, this study compared impact of ballast track (well, bad) and concrete track (sleeper embeded system, rail floating and sleeper floating) by field test to analyzing dynamic effect of track structure's characteristic and wheel load on service line. In addition, it suggested a method to generate reasonable track impact factor on each track type.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1093-1098
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• 2007

In designing the high-speed railroad track, it is important to utilize appropriate track components to maintain uniform stiffness and ensure track alignment within the tolerance set for that system. In this regard, continuous welded rails (CWRs) were introduced to the Korean railways. Yet the installation of CWRs can result in an adverse impact due to the track/structure interaction on bridge sections yielding variations in the stiffness at the expansion joints. It may also impose additional axial force, generate excessive stress or deflection on track, and loosen the ballast at the ends as a bridge deck contracts or expands owing to a thermally-induced dynamic response. The risk is even greater in a long bridge deck, resulting in track longitudinal irregularities, deteriorating passenger's comfort, and increasing maintenance efforts. This study evaluates the performance of ZLR and their impact on track longitudinal irregularities through the track measuring results on a test section installed the ZLR in order to minimize the thermally-induced responses and the maintenance efforts for the high speed railway bridges.