• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.489-492
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• 2011

장대레일 궤도의 부동구간에서 발생되는 과도한 축력은 혹서기 궤도의 좌굴을 유발시켜 주행하는 열차의 안정성을 위협할 수 있다. 궤도 제원을 제외한 압축응력과 관련된 레일온도 인자, 궤도 강성과 관련된 도상저항력, 궤도의 초기결함인 궤도틀림과 같은 인자들은 기후조건, 궤도 운영조건, 유지관리조건 등에 의해 임의적으로 변동되는 불확실성이 높은 궤도 매개변수이다. 그러므로 장대레일 궤도의 좌굴은 불확실성이 높은 현상임을 알 수 있다. 따라서 궤도 매개변수들의 불확실성 및 임의성을 합리적으로 고려하기 위해서는 확률론적 접근방법의 적용이 필수적이라 할 수 있다. 본 논문에서는 기존 본 연구진에 의해 개발된 장대레일 궤도의 좌굴확률 평가시스템을 이용하여 장대레일 축력을 산정하기 위한 필수요소인 중립온도의 확률분포 특성에 따른 좌굴 안정성을 분석하였다.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.203-211
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• 2015

Ride comfort of a vehicle can be utilized to maintain the track geometry and track irregularities because ride comfort of the rolling stock is affected by the characteristics of the vehicle and track. Ride comfort was evaluated according to the measured floor acceleration data of vehicles for a Korean high speed line as well as European high speed lines using Continuous comfort method which can be applied to track maintenance. The exceedance distribution of the ride comfort was quantitatively analyzed by the vehicle speed, the ride comfort of the Korean high speed line was compared with that of European high speed lines. It is shown that the ride comfort of Korean high speed line is better than that of European high speed lines, which indicates that the Korean track geometry and track irregularities are properly maintained.

• Journal of the Korean Society for Railway
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• v.9 no.2 s.33
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• pp.187-192
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• 2006

The regularity of railway track alignment is a crucial component fur maintaining travel safety and the smoothness of passenger ride. The conventional spectral analysis has been considered to estimate the severity of the track irregularity from measured data. The time domain data used to be changed into the frequency domain by Fourier transform. Because the measuring points can be regarded as the time points, the spatial-frequency can be introduced instead of the time-frequency. Although FFT(Fast Fourier Transform) and/or PSD(Power Spectral Density) function could provide fairly localized information within frequency domain, but chronical configurations of data could be missed. In this study, we attempt to apply the Morlet wavelet transform for the purpose of a frequency-time-domain analysis rather than a frequency-domain analysis. The applicability of wavelet transform is examined for the estimation of the track irregularity with real measured track data on the section of Kyoung-bu line by EM-120 measuring vehicle. It is shown that the wavelet transform can be an effective tool to manage the track irregularity.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1647-1652
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• 2008

Track geometry consists of tangent and curved lines, which caused undesirable changes in initial track geometry by traffic loads. The bigger the changes are, the worse the riding comfort and running stability of train. This is so-called track irregularity and is the most important quality parameters of ballasted track. To be able to objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies use moving chord method, this method determine versine values via a chord. The versine is the vertical distance to curve measured in the middle of the chord. This type of method measures only versine of track irregularity curve by transfer function from specific property of measuring tool. In this report, review the characteristics of two types of measuring tools by comparing the measurements. The one is GRP-1000 system, optical surveying system with Total station and lazar prism trolly. This calculates track geometry by surveying absolute coordinates of two points each on both rail heads. The other is Trackmaster, measures versine with 2m of chord length.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.450-457
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• 2000

This paper establishes a scheme to estimate track quality using standard deviation and deterioration rate of track irregularities. To provide index of quality, standard deviation and deterioration rate of track irregularities are analyed. As an index, standard deviation and deterioration rate were applied to decision of corrective maintenance and replacement maintenance, respectively. Further, this paper proposes a basic scheme for a modernization of mechanize track maintenance that using MTT(Multiple Tie Tamper) and Ballast Cleaner.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.535-544
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• 2011

The rail surface defects can cause the high impact load on the track and lead to the progress of the rail fatigue damage and the rail break. In case of the rail break, there is a great deal of risk for derailment, and thus the maintenance criteria for the rail surface defects are of great importance. In this study, using the dynamic train-track interaction analysis program, the impact wheel loads and rail bending stresses according to the depths of the surface defects have been calculated with the input data of the rail surface irregularities measured at 43 spots with surface defects in the ballasted track of high-speed railway. Considering the irregularity of track geometry, the allowable limits of wheel load and rail bending stress have been set, and the maintenance criteria for the rail surface defects was suggested by analyzing the relationship of the maximum values of wheel load and rail bending stress versus depth and width of rail surface defect. The analysis results suggest that the allowable depth of the surface defect is determined approximately 0.2mm from the limit of the impact wheel load.

• Proceedings of the KIEE Conference
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• summer
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• pp.1442-1444
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• 2004

현재 한국형 고속전철은 시운전 시험 중에 있으며, 차량 내에 상시 계측시스템이 구성되어 있어서 차량의 전기장치 신호나 기계장치 신호를 획득하여 주행 및 제동에 관한 성능 및 특성을 분석하고 파악할 수 있다. 하지만 차량의 안전성, 승객의 승차감 확보와 궤도의 빠른 유지보수를 위해 궤도를 전문적으로 감시하고 검측하는 시스템은 구축되어 있지 않다. 그러므로 고속전철 차량에 설치되어 고속주행 중에 궤도를 종합적이고 효율적으로 측정하는 전문적인 계측시스템을 구성할 필요가 있다. 따라서 궤도틀림의 검측방법과 검측기구 및 그 원리를 이해하고 선진국의 궤도 검측기술을 파악하여 보았다.

• Journal of Korean Society of Steel Construction
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• v.18 no.1
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• pp.47-51
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• 2006

Measuring the track geometry of a high-speed railway is the most important task in track construction and track maintenance work. Measuring accuracy is particularly sign the formulation of the maintenance plan and in the assessment of the work quality, and because it can set the train speed limit. To determine the track geometry of a high-speed railway, it is important to use KNR's track recording coach (EM-120). According to the result of the spectrum analysis, noise near the 1-m wave band was found on the track recording data. A new filter was thus applied to remove the noise from the track recording data. A similar result can be acquired when this method is used in real track geometry.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.151-163
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• 2008

A formulation of three-dimensional model of articulated train-b ridge dynamic interaction has been made for the Korean eXpress Train (KTX). Semi-periodic profiles of rail irregularities consisting of elevation, alignment, cross and gauge irregularities have also been proposed using FRA maximum tolerable rail deviations. The effects of rail joints and sleeper step were also included. The resulting system matrices of train and bridge are very spare, and thus, are stored in one-dimensional arrays, yielding a time-efficient solution. A numerical algorithm for computing bridge-train response including an iterative scheme is also formulated. A program simulating train-bridge interaction and solving this problem using the new algorithm is implemented as new modules for the f inite element analysis software named XFINAS. Computed results using the new program are then checked by that of the validated 2-D bridge-train interaction model. This new 3D analysis provides more detailed train responses such as swaying, bouncing, rolling, pitching and yawing accelerations, which are useful inevaluating passenger riding comfort. Train operation safety and derailment could also be directly investigated by relative wheel displacements computed from this program.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2400-2404
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• 2011

Power spectral density (PSD) model of irregularities for the maglev test track is presented. Track irregularities (gauge, cant, twist and vertical) were calculated from the survey data of sleepers on the test track. PSD model was constructed from the estimated PSDs of each track irregularities. Versine (gauge, cant, twist, vertical and lateral) of the track is obtained and their PSDs were estimated, too. Presented PSD model can be used for the analysis of levitation stability and ride quality of the maglev system.