• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1093-1098
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• 2007

In designing the high-speed railroad track, it is important to utilize appropriate track components to maintain uniform stiffness and ensure track alignment within the tolerance set for that system. In this regard, continuous welded rails (CWRs) were introduced to the Korean railways. Yet the installation of CWRs can result in an adverse impact due to the track/structure interaction on bridge sections yielding variations in the stiffness at the expansion joints. It may also impose additional axial force, generate excessive stress or deflection on track, and loosen the ballast at the ends as a bridge deck contracts or expands owing to a thermally-induced dynamic response. The risk is even greater in a long bridge deck, resulting in track longitudinal irregularities, deteriorating passenger's comfort, and increasing maintenance efforts. This study evaluates the performance of ZLR and their impact on track longitudinal irregularities through the track measuring results on a test section installed the ZLR in order to minimize the thermally-induced responses and the maintenance efforts for the high speed railway bridges.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1299-1305
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• 2006

In this paper, the objective is an evaluation of economics using Life Cycle Cost(LCC) analysis for the ballasted track and the concrete track. However, since the absence of reliable data on maintenance activities, the degree of a reliability about the results of the LCC analysis is insufficient yet. In order to remedy the problems, we surveyed a professional research group for an approximate estimation which can be represented a degree of maintenance through a application of examples. Hereby we found that it is possible to expect the retrenchment of cost using preventive maintenance management. Moreover we proposed appropriate and economical restrictions between track structures.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.370-375
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• 2005

Floating sleepers in a ballasted track increase both track deterioration and track irregularities. Consequently, a considerable maintenance work is required and maintenance cycle is shortened due to the floating sleepers. This paper quantifies the degrees of void between the floating sleepers and a ballast bed. In the future, the influence of floating sleepers on the track will be investigated by an analytical method using a dynamic model.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.666-671
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• 2002

All work related to maintenance of track has been impletemented on the basis of the measured result from EM series cars in Korea. However, since these types of cars measure only versine value of the track irregularities instead of the real ones, this method will cause the confusion to maintenance operators if commercial speed should increase. This study was showing and explaining the program developed to get the real irregularities from the versine value. Finally, the reconstruction profiles completed by two different methods were compared with artificial track irregularities to confirm the their practicality.

• 한국철도학회논문집
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• 제15권2호
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• pp.172-178
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• 2012

현행 철도건설기준에서 종곡선과 완화곡선의 경합은 궤도형식에 관계없이 허용하고 있지 않다. 그러나 이러한 기준은 주로 자갈도상궤도의 유지보수의 어려움 때문에 정립된 것이다. 콘크리트궤도는 자갈도상궤도에 비해 유지보수 및 구조안전성 측면에서 장점을 가지고 있다. 따라서 콘크리트 궤도의 경우, 열차의 주행안전성 및 승차감 기준을 만족하는 범위내에서 어느 정도의 선로경합은 완화할 필요성이 있다. 본 연구에서는 종곡선과 완화곡선의 경합여부에 따라 도상종별 열차의 주행안전성 및 승차감, 그리고 궤도작용력을 비교 분석하였으며, 그 결과 경합된 경우도 주행안전, 승차감 및 궤도작용력 기준을 만족하는 것으로 나타났다. 따라서, 비록 자갈도상궤도에서의 선로경합은 많은 유지보수를 필요로 하기 때문에 적용될 수는 없다 할지라도, 콘크리트궤도에서는 유지보수 및 구조적 장점을 고려할 때 종곡선과 완화곡선의 경합이 적용될 수 있을 것으로 판단된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1029-1037
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• 2008

As for track maintenance, Seoul Metro executes track bed improvement project from obsolete ballast track bed to concrete track bed in order to achieve maintenance free and to extend its LCC(Life Cycle Costing). When it comes to obsolete ballast track bed withdrawal task, now it is done solely relying on man power and ballast inhalation vehicle. In this paper, I suggested ballast cleaning system with lighter equipment to change manpower withdrawal tasks to mechanized ones. It is expected to improve work efficiency and economic benefits by applying track excavator having variable wheels and container etc, which is able to keep on the site.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.317-324
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• 2007

Until now, the railway has been constructed using track with jointed rails of relatively short lengths to allow thermal expansion in hot summer months. These joints weaken the track structurally and increase track maintenance cost and power consumption of the running train. The CWR(Continuous Welded Rail) Track is the solution of these drawbacks. Although the CWR track not only reduces the track maintenance cost but also increases the life cycle of track components, the stability of the track is highly affected by change of temperatures and vehicle load. A three dimensional nonlinear analysis which considers rail, fastening system and tie has been performed to understand structural behavior of the CWR track. In this case, the translational and rotational stiffness values of fastening system have not been studied. The fastening system makes ties and rails connect. In this study, the stiffness values of various types of fastening systems which consist of clips, rail-pads and insulators are determined by the experiment. The experimental results of the fastening system are compared with the results of parametric study that is performed to investigate the sensitivity of fastening system on stability of CWR track.

• Journal of Astronomy and Space Sciences
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• 제14권2호
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• pp.355-366
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• 1997

This paper presents a comprehensive analytical approach for determining key maneuver parameters associated with the acquisition and maintenance of the ground track for a low-earth orbit. A livearized model relating changes in the drift rate of the ground track directly to changes in the orbital semi-major axis is also developed. The effect of terrestrial atmospheric drag on the semi-major axis is also explored, being quantified through an analytical expression for the decay rate as a function of density. The non-singular Lagrange planetary equations, further simplified for nearly circular orbits, provide the desired relationships between the corrective in-plane impulsive velocity increments and the corresponding effects on the orbit elements. The resulting solution strategy offers excellent insight into the dynamics affecting the timing, magnitude, and frequency of these maneuvers. Simulations are executed for the ground track acquisition and maintenance maneuver as a pre-flight planning and analysis.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(III)
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• pp.252-257
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• 2003

It is necessary to have a maintenance of track and its equipment for safety and s the railroad transportation. In the paper, we examine the safety problems, protecti and composition of protection system for safety within the track which RTRI develo system consists of a mobile business tool carried by each worker. a terminal of t platform temporarily installed in the maintenance car. a connector attached to signalling system and a central administrative device installed at the control cen used independently to detect positions of workers and maintenance cars. Each m correctly grasp the geometrical relations with other workers cars and other objects conditions based on the state information exchanged between the machines by the control protocol. the track occupancy monitor information broadcast by th administrative device and the line information. The protection system executes its f this basic structure.