• Proceedings of the KSR Conference
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• 2007.05a
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• pp.325-339
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• 2007

This paper presents the analysis results to evaluate the application of separation sleeper boot of turnout in concrete track in subway. An analysis includes the dynamic load on turnout-bridge and the ballast improvement method of upbound and down line independent girder in servicing line. From the results, the aspect and the property of separation sleeper boot of turnout are evaluated. FE analysis explain the relationship between independent bridge and track behaviour of dynamic loads. The assessment of application based on FE analysis results in a good improvement method of servicing subway line is proposed.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.303-310
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• 2007

In this paper, the correlation between the vibration characteristics of the track components and the parameters affecting the vibration is analysed. To do it, the accelerations of each track component such as rails, sleepers and ballast are measured in Kyong-Bu high-speed railway lines. The RMS values of the measured data are calculated and the corrugation, the track irregularity and the pad stiffness are considered as the parameters in the viewpoint of track. By using the linear regression, the correlation coefficient is calculated to analyse the relationship. The parameter whose correlation coefficient is more than 0.7 is considered as the major one. Also, the 1/3 Octave analysis is calculated to analyse the dominant frequency band of the vibrations of the track components.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.299-304
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• 2010

We should manage the target locations according to the deterioration degree of the ballast for the rational and economical ballast cleaning. For this, it's required to define the logics calculating the crushing rates and suggest the threshold values for the ballast cleaning. This paper introduce the system modules that estimate the ballast's deterioration degree refers to the results of the previous study("A Study on the Crushing Characteristic of the Ballast Gravel at High-Speed Railroad", Journal of the Korean Society for Railway, Vol.11, No.4, pp.384~389), enroll the target locations where the ballast cleaning is required.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.997-1002
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• 2009

The local loosening of ballast supporting railway tract cause a differential vertical tract settlement. In the bridge, the temperature change make bridge deck to contract and expand, and this movement cause local loosening of ballast on the bridge expansion joint. Therefore, the evaluation of the status of ballast on the bridge expansion joint is important for the track maintenance of the high-speed railway. In this paper, hwaw method was applied to evaluate the status of ballast on the bridge expansion joint. HWAW method is non-destructive test to evaluate 2-D shear wave velocity map along the railway. Shear wave velocity is directly related with status of ballast. In this research, hwaw method was applied two different types of bridges and determine the degree and the range of the ballast loosening caused by movement of the bridge expansion joint.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.84-90
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• 2009

The gravel ballast in the ballasted track has the function to not only transfer/scatter the train loads to subgrade through rail and sleeper but also elastically support the train loads. Because track irregularities results inevitably from the repetitive train loads, the track maintenance should be undertaken for correcting them. By analyzing the track maintenance history in the Gyeongbu high speed railway, this study tries to choose the local two spots in the railway in which the repair frequencies are maximum and relative small; to analyze their dynamic characteristics as well as grade; and to compare them with maintenance history. As the dynamic characteristics of track, the vertical displacement and vibrating acceleration of sleeper as well as acceleration of ballast are measured/analyzed. Furthermore, by collecting soil and gravel on the reinforced roadbed and undertaking ballast screening test, the size distributions are compared with grade distribution standards of high speed railway.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.854-859
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• 2005

The major objective of this study is to investigate the dynamic behaviors of track due to the deterioration characteristics of ballast for servicing tracks by the field test. The durability of ballast plays an important role in the track behaviour. To estimate the deterioration characteristics of ballast, several tests have been carried out by several shcolars. The deterioration characteristics of ballast is one of the most important factor in the dynamic behaviour of track and its life. In this paper abrasion/breakage characteristics of ballast is studied to predict the effect of physical ballast characteristics on ballast track. To reveal deterioration characteristics of ballast, the field test were carried out. The deterioration characteristics, studied in this paper, is applied to the dynamic behaviour of track in various conditions.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.484-493
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• 2006

This paper is presented the test results to evaluate the healthiness of the ballast in subway. The test includes the dynamic load test in servicing Line the screen classification test of aggregates and the wear test. From the results, the aspect and the property of the ballast are evaluated. The dynamic load tests the relationship between the deterioration of the ballast and the fluctuation of loads. The assesexplain sment of impact factor based on the field test results in a good property of test blocks is proposed.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.223-231
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• 2018

Recently, due to various environmental problems, blast tracks in tunnel are replaced with concrete tracks, but they have more adverse effects on noise than blast tracks so that additional noise measures are needed. Among these measures, sound-absorbing blocks start to be used due to its easy and quick installation. However, the performance of sound absorption blocks need to be verified under real environmental and operational conditions. In this paper, interior noise levels in KTX train cruising in Dalseong tunnel are measured before and after the installation of sound-absorbing blocks and the measured data are analyzed and compared. Additionally, noise reduction are estimated by modeling the high speed train, the tunnel and absorption blocks. Measurement devices and methods are used according to ISO 3381 and the equivalent sound pressure levels during the cruising time inside the tunnel are computed. In addition to overall SPLs(Sound Pressure Levels), 1/3-octave-band levels are also analyzed to account for the frequency characteristics of sound absorption and equipment noise in a cabin. In addition, to consider the effects of train cruising speeds and environmental conditions on the measurements, the measured data are corrected by using those measured during the train-passing through the tunnels located before and behind the Dalseong tunnel. Analysis of measured results showed that the maximum noise reduction of 6.8 dB (A) can be achieved for the local region where the sound-absorbing blocks are installed. Finally, through the comparison of predicted 1/3-octave band SPLs for the KTX interior noise with the measurements, the understanding of noise reduction mechanism due to sound-absorbing blocks is enhanced.

• Journal of Korean Society of Steel Construction
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• v.17 no.6 s.79
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• pp.673-679
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• 2005

According to continuous welded rails on a bridge, temperature changes bring about the expansion of the bridge deck,adding axial forces on the track. Moreover, the ballast on the bridge deck expansion joint is moved due to the bridge deck. The longer the bridge deck is, the greater the influence will be, loosening the ballast, causing track irregularities, and deteriorating passenger comfort. Considering the structure of the bridge itself and tolerance for track irregularities caused by the loosened ballast on the bridge, the maximum length of the deck should be less than 80 m, which is the same as the standard of French railways. In this study, the interaction between the expansion related to the bridge length and the irregularity in the longitudinal level, referring to measurements and maintenance work performed in high-speed railways, was analyzed. This research shows that the installation of a sliding plate or a vertical ballast stopper is not a good option, since it is difficult. On the other hand, the installation of a ZLR fastener or gluing is easy, but its influence is insignificant. In conclusion, switch tie tamping or manual tamping is more effective than other methods of what?

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.384-388
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• 2019

In winter season, the snow and ice accretion on the bottom of the high speed railway rolling stock and boogie part has fallen at a high speed from the ballast section (gravel section for the transmission of the rolling stock load received by sleepers and fixing sleepers), causing the gravel to be scattered, thereby damaging the railway rolling stock structures and facilities. In order to solve these problems, the gravel scattering prevention net, manual de-icing, and movable hot air machine were used, but their efficiency was low. For the more efficient de-icing than ever before, an optimum material for de-icing fluid for high speed railway rolling stock was developed by evaluating the ice melting capacity, kinematic viscosity, evaporation of the material used as a chemical de-icing fluid. Four kinds of organic acid salts (sodium formate, sodium acetate, potassium formate and potassium acetate) and two different alcohols (propylene glycol, glycerol) were used as evaluation materials. Potassium formate, potassium acetate, and propylene glycol had similar ice melting capacities in the indoor test, but the propylene glycol showed the best ice melting capacity in spraying the system simulation test. This is because the kinematic viscosity of propylene glycol was 2.989029 St, which is higher than those of other materials therefore, it could stay longer on the ice and de-icing. In addition, potassium formate and potassium acetate were difficult to be used since the crystals precipitated and adversely affected the appearance of the rolling stock. The propylene glycol is the most optimum as an de-icing fluid for the high speed railway rolling stock.