• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 추계학술대회 논문집(II)
• /
• pp.129-134
• /
• 2003

It is very important to pay careful attention to construction of bridge/earthwork transition zone for high-speed 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. An abrupt change of stiffness across two adjacent track portions cause irregular settlement of roadbed, track irregularity, lack of girder bending moment and reduction of lateral resistance. Especially on high-speed railway, track irregularity of transition zone cause sincere effect to track stability and train safety. And so continuous maintenance is needed. To verify this effect and to improve transiton zone capacity, In situ test, track irregularity and train acceleration test were performed on high-speed railway bridge/earthwork Transiton Zone.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 1999년도 춘계학술대회 논문집
• /
• pp.442-449
• /
• 1999

Due to temperature variations, considerable longitudinal rail forces and displacements may develop in continuous welded rail(CWR) track on long-span bridges or viaducts. Excessive relative displacements between sleepers and ballast bed may disturb the stable position of the track in the ballast which results in a lower frictional resistance. Generally, these problems are solved by installing rail expansion devices. However the application of expansion devices in high-speed tracks on existing bridges, as a means to prevent excessive longitudinal displacements and forces, is not attractive method due to comfort, safety and maintenance aspects. An alternative and very effective solution is possibly the use of so-called zero longitudinal restraint(ZLR) fastenings over some length of the track. The calculations, carried out in this respect, show a considerable reduction of track displacements, track forces, and the relative sleeper/ballast displacements. This reduction depends on the length over which these fastenings are installed. In this paper calculations of the longitudinal displacments and forces in a CWR track and substructure resulting from thermal, mechanical and kinematical loads were carried out using the FEM analysis program LUSAS

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.330-337
• /
• 2010

This paper shows an algorithm for identifying track irregularities using wavelet transfer function along the railway. An equivalent SISO wavelet transfer function is defined using continuous wavelet transform by the measured track geometry and acceleration at a bogie of a train. The estimated track geometry is made by inverse continuous wavelet transform from the regressed signals of measured acceleration signal and the pre-defined wavelet transfer function. The estimated rail irregularity geometry is evaluated by the coherence function and comparison of FRF(Frequency Response Function). As a result of evaluated outcome, This algorithm is regarded as appropriate for estimation of rail irregularity.

• 한국강구조학회 논문집
• /
• 제12권6호
• /
• pp.727-736
• /
• 2000

본 연구에서는 궤도의 좌굴해석 및 그 결과를 통해 열차하중이 직선 및 곡선 장대레일 궤도의 온도좌굴 거동에 미치는 영향에 대해 평가하였다. 차량을 고려한 온도좌굴 해석은 바퀴하중하에서 장대레일 궤도의 수직 처짐에 기인한 상향처짐을 결정하기 위해 유사정적 하중모델을 가정하였으며, 차량의 무게와 속도, 궤도의 곡률, 캔트, 그외의 열차와 궤도의 동적인 상호작용으로 인한 횡방향하중은 열차의 수직하중에 대한 수평하중 비에 포함하여 수행하였다. 수치적 해석을 통해 장대레일의 상부 및 하부좌굴온도를 구하였고, 이런 해석결과들을 기존의 열차하중을 포함하지 않은 정적 좌굴해석결과들과 비교하였다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2002년도 추계학술대회 논문집(I)
• /
• pp.654-659
• /
• 2002

Continuous Welded rail(C.W.R.) tracks has many advantages over the conventional jointed rail track. Due to the elimination of rail joints for thermal expantion, however it many cause the track to be suddenly bucklled by thermal loads. The present study investigates the influences of Pad-fastner on the Thermal buckling behavior of C.W.R. Parametric studies are performed to evaluate the effects of the individual parameters on the upper and lower critical bucklig temperature.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 추계학술대회 논문집(II)
• /
• pp.117-122
• /
• 2003

Cheongdam Bridge in Seoul Metropolitan Subway Line No.7 recently constructed has 180 meters (2@90m) of expansion length of structure (distance between fixed points). Track type is all ballasted track and rail expansion joint is installed at every movable point. However, there is no expansion joint at the transition area between ballasted track ,end deck. By this reason, the rail buckling has been occurred every year and there is actually an abnormal behavior in expansion. In this study, based on the modeling of the Cheongdam Bridge, the element of interacting relationship between track and structure which is influential to track displacement in long-span bridge was analyzed and, finally, the methodology to ensure the continuous-welded rail in Cheongdam Bridge was suggested.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 춘계학술대회논문집
• /
• pp.561-566
• /
• 2003

In this paper, a numerical method for evaluating the efficiency of vibration reduction of substructure under floating slab track is developed for optimal design of floating slab track. The equation of motion for train and track interaction system is derived by applying compatibility condition at the contact points between wheels and rails. The train is modelled by 3-masses system and the track by continuous support beam system. Numerical analyses are carried out to investigate the effects of train speed, stiffness and damping of slab-pad, and track irregularity upon vibration reduction in substructure under the track.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.1058-1070
• /
• 2007

Internal and external railway management corporations are using the periodic replacement criteria of rail by accumulated passing tonnage and wear to maintain rails for servicing. However, internal the periodic replacement criteria of continuous welded rail(CWR) by accumulated passing tonnage is the one(50kg/m-5 million gross tonnage, 60kg/m-6 million gross tonnage) presented in Japan before. It was estimated with the fatigue life about 50kg N rail joints applied diesel train load but it wasn't applied to current conditions of track; elimination of rail joint, using the concrete slab track and operation of light train load and effect of welding, manufacturing technique, grinding of rail. Therefore, in this study, it was investigated the types of damage and cause in welded rails and examined standards and information resources. Also, this study presents preliminary data to revise the periodic replacement criteria of CWR by current accumulated passing tonnage in bending test of laid welded rail and a survey of track maintenance history of Seoul metro.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
• /
• pp.369-375
• /
• 2009

The Periodic replacements criterion of rail is calculated on the basis of the research result of RTRI in Japan. It is suggested that the service life of the continuous welded rail(CWR) is estimated by the relationship between the rail surface irregularity according to the accumulated passing tonnage and bending fatigue of welded part in CWR. In order to establish the periodic replacements criterion of CWR, this study measured the rail surface irregularity according to the accumulated passing tonnage, the types of track system and welding. Therefore, it is analyzed that the gas pressure welding is the worst one of the others. In addition, it is analyzed that the rail surface irregularity growth rate in ballast track is about $0.02{\sim}0.03mm$/100MGT and its in concrete track is about $0.005{\sim}0.02mm$/100MGT Finally, the result of this study is able to use the basis data to establishing the periodic replacements criterion of CWR considering rail grinding.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 추계학술대회 논문집
• /
• pp.1264-1269
• /
• 2008

We designed a track circuit of Tag in-tag out type that can be used for light rails and monorails. This method is called RFID-Tag and it literally uses RFID-Tag and replaces a fixed track circuit and implements a moving block. The distance between RFID-Tags is set to the length of a train and thus a train is always in contact with one of the tags. A train runs in RFID-Tag in -RFID-Tag out type at all times and the distance between trains can be precisely controlled through the application of a moving block combined with the basic principle of a fixed block, which enables the continuous speed control and enhances the satisfaction of passengers. When constructing a track circuit using RFID-Tag the Tag in-tag out brings us the cost reduction and is more economical than the existing fixed track circuit in that sense and easy for installation and maintenance. The wireless communication between onboard and wayside makes the continuous control possible and can improve the control capacity of ATP/ATO by the implementation of a moving block on top of a fixed one.