• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1056-1061
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• 2007

Railroad roadbed was consisted into structure types that earthwork, tunnel, bridge and joint sections. Joint section was affected a large factor confidence and safety of the train running by stiffness transition zone that track substructure stiffness change section as like between tunnel and earthwork from ballast track to concrete track. These problems are the results of increased dynamic wheel loads, which also lead to wear and tear on vehicle components and contribute to poor ride quality. The study presented in this paper was conducted on model test by using Wheel Moving Loading System.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1433-1437
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• 2007

This paper describes the detection algorithm which can distinguish series arcing signal from voltage harmonics or noises produced by the operation of non-linear loads. A high pass filter with the cutoff frequency of 3 kHz is designed and it can attenuate power frequency signal to 80 dB. Series arcing phenomena is simulated to an incandescent lamp controlled by a dimmer. From the experimental results, it is confirmed that the amplitude of the filter output voltage varies at random during series arcing but the signal generated by non-linear loads appears on a regular basis. We proposed a series arcing detection algorithm using the chaotic nature of voltage signal.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.113-118
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• 2009

It is of utmost important that track loads at rail induced by running train was usually obtained for track performance evaluation. A reaction force of track was measured wheel loads and lateral force by strain gauges on the rail, and then it was obtained to derailment coefficient and variational ratio of wheel load from its relationship. In this study, a existing monitoring system methods with many manpower working were reviewed about measurements, process of testing, and how to obtain accurately measured data.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.485-492
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• 2000

In the rail facilities the rail track consists of rail tie fastening accessories and bed,. The rail track is largely divided into Ballast Bed Track(BBT) and Concrete Bed Track(CBT) according to the type of bed. In this thesis among Concrete Bed Track slab track which is used for the Japanese high speed railway is a target of this study. Dynamic analysis by using finite element method are performed. where moving rain load is periodic function. Then through parametric study some conclusions are obtained as follow. Cement Asphalt Mortar(CAM) affects contrary mechanical behavior to rail and slab greatly. Therefore change of CAM spring coefficient should be handled with care, For slab thickness thin slab is more profitable to reduction of vibration of rail than thick one but mechanical capacity of slab is deteriorated, Improved structural type is proposed then structural analysis is performed for this one. This type is effective to reduction of vibration of railway system.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.435-441
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• 2011

Track geometry changes 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 objectively assess track irregularity, track geometry should be able to be measured. Practically, railway companies in Korea use various track recording equipments to measure track irregularity. But this various equipments output different data due to their geometrical structure even measured at same location. In this report, the correlation of various track recording data used in Korea was reviewed.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.268-274
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• 2011

In railway, Ballast plays an essential role as intermedium in transmitting train load to subgrade safely. Gyoung-Bu HSL 1st phase consists of ballasted track except for over 5km long tunnels. Ballast track occurred track irregularity by train loads and requires periodic maintenance work. However, Repetitive train operation and tamping work cause to accelerate track irregularity and ballast deterioration such as abrasion and crushing. For these reason, Track irregularity areas had occurred ballast cleaning work to improve track quality. However, for the train to run safety, ballast cleaner working area needs train speed reduction and track stabilization work due to ballast relaxation and initial settlement. In this study, according to train speed-up and cumulative traffic tonnage, we measured and analyzed the track settlement and acceleration of sleepers to evaluate of track stabilization in order to keep the ballast condition stable after cleaning work.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3195-3200
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• 2011

The vibration resulting from railway operation is transmitted through the track and line structure, ground movements to adjacent buildings. As these vibration is growing, there is occurred exaggerated forces and displacements of the track and line structure and it is causing the differential settlement. It is difficult to clarify the dynamic response characteristics of trackbed because of various environmental conditions. However, track irregularity be affected by ununiformed bearing capacity and its dynamic response, study for dynamic response characteristics is required to investigate the cause of track irregularity and countermeasure. This study was intended to evaluate the numerical analysis which exam the response analysis characteristic of ground vibration by shape of cutting and embankment transition zone. The original method of analysis were have to examine variables such as directions, angles, drain conditions, linear conditions. However, In the analysis there were to consider the effect of moving loads according to directions of cutting and embankment transition zone.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.563-568
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• 2003

High-speed railway bridges subject to effect of dynamic loads by interaction between vehicle load which run specially fast and behavior of bridges. Such dynamic load effects result in fluctuations and fatigues to each elements as well as whole conduct of bridges. and is influenced in life of bridges. For these reason. Analysis and estimation of data about dynamic behavior of bridges occupies important factor in that estimate the remaining life of bridges and select the maintenance. repair and retrofit. In this paper. Analysis for the dynamic behavior of bridges using displacement and acceleration data that is actuality measure data to the bridges of Seoul-Susan high speed railroad test section has been made.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1279-1286
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• 2006

It is very important to pay careful attention to construction of earthwork/tunnel transition zone for railway. The transition zone of the railway is the section which roadbed stiffness is suddenly varied. Differences in stiffness have dynamic effects and these increase the forces in the track and the extent of deformation. In this study, performance of transition zone was investigated through the field tests. The wheel loads and sleeper settlement were measured after installing field testing sections.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.6
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• pp.615-621
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• 2015

In this paper diamond wire cutting method has been proposed to cut the rock in the tunnel face. Diamond wire saw method could cut the rock from tunnel face with very minor vibration and noise. In this study rock cutting process has been simulated with FEM method by using LS-DYNA explicit non-linear finite element code. Normal load act as an prime factor when cutting the rock surface. For observing the effect of normal load on bead, several experiments has been conducted by varying normal loads on the bead. From each experiment, cutting rate has been calculated to compare the cutting rate with different load conditions. By increasing the normal load on bead, cutting rate increases drastically.