• International Journal of Railway
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• v.2 no.3
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• pp.118-123
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• 2009

Railway track alignment Standards set a minimum lenght value for straight and circular alignments (art. 5.2.9.), in order to ensure passenger ride comfort in railway vehicles of which dynamic oscillations will thus have to be limited. The transitions between alignments can cause abrupt changes (usually called discontinuities or singular points of the alignment) of curvature, of rate of change of curvature or of rate of change of cant. A passenger is likely to experience effects due to the excitation of the elastic suspension of the vehicle which generates oscillations that are damped as the vehicle moves away from the singularity. The amplitude of these oscillations should be adequately attenuated by the damping of the suspension system within the interval between two successive singular points, especially to avoid resonances. Therefore minimum lengths between two successive singular points are stated in alignment standards. Nevertheless, these nonnative values can be overly conservative in some cases. As an alternative, track alignment designers could try to assess how much the excitation has been attenuated between two successive singular points and thus assess at which point a new singularity may be present without affecting ride comfort. Although such assessment can be made with commercial SW packages which simulate the dynamic behavior of a vehicle considered as a set of rigid bodies interconnected with elastic elements simulating the suspension systems (such as SIMPACK, ADAMS or VAMPIRE), a simplified and user-friendly computation method (based upon the analytical solution of differential equations governing the phenomenon) is made available in this paper to track design engineers, not always used to working with full dynamic models.

• Journal of the Korean Society for Railway
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• v.12 no.4
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• pp.597-603
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• 2009

In this study, Based on the optimization developed in Um et al. (2009), optimum design method of the alignment when building new lines and renewing existing ones is presented. The object function used for optimization is passenger comfort ($P_{CT}$) which was proposed in BSI (2006). Other aspects of track/vehicle interaction will be treated in boundary conditions. And track/vehicle interaction analysis is peformed using KTX-II model. From the analysis results, it was found that the optimum alignments are affected by the angle (I) between adjacent straight lines and $R-L_t$ combinations. Also the dynamic analysis confirms well the results from the simplified analysis. However, In the most cases, the $P_{CT}$ values in the dynamic analysis are higher than the simplified $P_{CT}$ values. If both methods are used when optimizing the alignment, it will be possible to design the alignments more rapidly and reliably.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.265-269
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• 2006

In this study, horizontal alignment of railroad obtained by digital photogrammetry method. The two-dimensional horizontal alignment was reappeared by camera calibration and digital image data. This method's result showed more satisfactory value than existing survey method in horizontal alignment of railroad. Hereafter, this method would be a appropriate method lot the decision of railroad facility' position in small rural area and construction of DB for the design of alignment.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.1
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• pp.63-71
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• 2004

This research is to reconstruction of railway alignment using GPS data, an investigation is made on the method of optimum simplification for reduction of unnecessary linear data, improve the accuracy by using four simplification algorithms among the methods. By applying two measured of displacement between observed data and it's simplification methods have been evaluated. The results showed that the complexities of lines is not practical to investigate simplification algorithms, the Douglas-Peucker method produced a little displacement between observed data and it's simplification. Its by using the Douglas-Peucker method to observed linear GPS data in railway track, design elements of horizontal alignment have been calculated. Then we could know that obtain the good results fur reconstruction of alignment elements through the methods and algorithns of this study.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.4
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• pp.391-400
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• 2004

Railway curved zone have crucial effects on the speed of train. Length of transition curve is one of the important factor for alignment compatibility estimation in this sections, this value is decided by running speed and Cant. In this study, the extension method of transition curve is evaluated, based on the alignment of Jang Hang-Line, investigated field conditions of the sections in the curves exist. This research result show that changing of transition curve was proved by necessary to approximately two thirds of the curved sections, and method of fixing central point of track centerline and changing radius of curvature minimize the maximum shift in track centerline and deviation of radius, and also may be effective method for alignment suitability and speed up in case overall improvement is difficult.

• Journal of the Korean Society for Railway
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• v.13 no.3
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• pp.309-316
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• 2010

When the horizontal and vertical curves are superimposed in railway alignments, which affects the running stability, ride comfort, and track maintenance costs. However, when designing new lines or realigning existing ones, there are many cases of superimposition caused by the existing fixed points (bridge, tunnel, turnout, and catenary system, etc) on the conventional lines and undesirable impacts on the environment, etc. In this study, when the horizontal and vertical curves are superimposed, in order to optimize the horizontal curve in aspect of the ride comfort, the object function was developed and verified by vehicle dynamic analysis. Also, the solution algorithm for simplified evaluation method was presented.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.376-381
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• 2005

This paper presents the rail structure interaction analysis of the elevated viaducts which contains the curved alignments with smallest radius of 300 metre. The aim of this study is to check the compatibility between the track and the curved structure in order to verify the safety of the continuous welded rail track under service conditions. To perform the rail structure interaction analysis, nonlinear static rail structure interaction calculation is implemented. The bridge structures, the rails and the track behaviour are modelled according to the UIC774-3 and the Eurocode prEN1991-2 recommendations. Criteria in Eurocode prEN1991-2 are investigated to check the compatibility between the track and the structure for the rail structure interaction effects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.614-627
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• 2018

Urban railway lines have been constructed adjacent to residential buildings and urban areas. The expansion of transportation networks and reconstruction of residential buildings in highly populated urban areas require deep excavations in areas adjacent to urban railways. Mobilized soil stresses and changes in the groundwater level induced by deep excavations results in track irregularities in urban railways. In this study, a three-dimensional finite difference model using the commercial program FLAC3D was adopted to estimate the horizontal displacements of earth retaining structures, settlements of backfill, the stability of track irregularity and underground box structure based on the criteria of each railway organization and its relationships. In deep excavations, a change in groundwater level induces relatively very small differences for track gauge irregularities, whereas relatively large differences for longitudinal irregularities of 72.5%, twist irregularities of 83.3%, cross level irregularities of 61.9%, and alignments of 43.3% were found to be the maximum differences when the horizontal displacement of earth retaining wall and settlement of backfill were 65.1% and 21.4%, respectively, because the groundwater level (GWL) on the ground surface-mobilized tensile strength of the underground box structure exceeds the allowable value. Therefore, three-dimensional numerical analysis was performed in this study. Overall, real-time monitoring should be carried out to prevent railway accidents in advance when a deep excavation adjacent to urban railway structures is constructed.

• Journal of the Korean Society for Railway
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• v.18 no.5
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• pp.457-465
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• 2015

A method of evaluating the optimal alignment range while considering ride comfort when performing line renewal of curved tracks for speed-up is proposed in this study. The proposed method was applied to analyze the optimal renewal range for horizontal alignments with the smallest curve radii in the Kyung-Bu high-speed line; a parametric study on the effects of various initial design conditions on the permissible renewal range and optimal alignment range was also performed. From the analysis results, it was found that the permissible range is enhanced in proportion to the increase in the curve radius and the cant. It was also verified that a slight adjustment of the horizontal alignment enables speed-up even in the case of R7000/R8000, placed in the ballasted track section of the Kyung-Bu high-speed line.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.24-30
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• 2008

One of the characteristics of the Maglev Train is the prominent capability of upgoing. Maglev train with the aim of longitudinal slope 7/100 is under development by the Center for Urban Maglev Program in Korea. To realize these slope, vertical curves must be inserted before and after the slope. The inserted curve has the radius of 3,000m generally. The insertion of these vertical curve results in the additional differences between the girder upper face and the guide rail, and the alignments are controlled by cast in place concrete at present. In this study, for longitudinal curved route with longitudinal slope 6/100, the applicability of PSC-U type girder and precast deck was evaluated for the span length 25m, 30m and vertical curve radii with 3,000m and 1,500m with respect to longitudinal slope 6/100.