• Steel and Composite Structures
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• 제33권2호
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• pp.209-224
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• 2019

This paper describes a study of the mapping relationship between the vertical deformation of bridge structures and rail deformation of high-speed railway, taking the interlayer interactions of the bridge subgrade CRTS II ballastless slab track system (HSRBST) into account. The differential equations and natural boundary conditions of the mapping relationship between the vertical deformation of bridge structures and rail deformation were deduced according to the principle of stationary potential energy. Then an analytical model for such relationship was proposed. Both the analytical method proposed in this paper and the finite element numerical method were used to calculate the rail deformations under three typical deformations of bridge structures and the evolution of rail geometry under these circumstances was analyzed. It was shown that numerical and analytical calculation results are well agreed with each other, demonstrating the effectiveness of the analytical model proposed in this paper. The mapping coefficient between bridge structure deformation and rail deformation showed a nonlinear increase with increasing amplitude of the bridge structure deformation. The rail deformation showed an obvious "following feature"; with the increase of bridge span and fastener stiffness, the curve of rail deformation became gentler, the track irregularity wavelength became longer, and the performance of the rail at following the bridge structure deformation was stronger.

• International Journal of Railway
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• 제2권4호
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• pp.139-146
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• 2009

Vehicle braking in non-electrified rail systems wastes energy. Advanced flywheel technology presents a way to capture and reuse this braking energy to improve vehicle efficiency and so reduce the operating costs and environmental impact of diesel trains. This paper highlights the suitability of flywheels for rail vehicle applications, and proposes a novel mechanical transmission system to apply regenerative braking using a flywheel energy storage device. A computational model is used to illustrate the operation and potential benefits of the energy storage system.

• International Journal of Railway
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• 제2권1호
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• pp.22-29
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• 2009

A simple pendulum shows how efficient gravity is in recovering energy. Any transportation is a linearly oscillating system; every load gains kinetic energy, but loses the same to come to a stop. The Gravity Power Towers comprise of a set of vertically moving heavy masses coupled, through microprocessor controlled continuously variable gear and cable system, to a horizontally rolling unit on wheels either on rail or road. The heavy masses move vertically up against gravity gaining potential energy while stopping a moving mass; move down under gravity force, giving out energy. The Tower thus accelerates or sustains the speed a rolling unit, and while decelerating, recover the kinetic energy. Speeds of 360 kmph can be attained. Recovery of energy varies from 98.5-70%; the longer the distance between stops, the lesser is recovery. The economical, omnipresent & eternal Gravity Power grants energy independence to many a nation. Global warming reduces.

• Smart Structures and Systems
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• 제18권5호
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• pp.1063-1085
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• 2016

Taking advantage of the high sensitivity and long-distance detection capability of acoustic emission (AE) technique, this paper focuses on the crack detection in rail head, which is one of the most vulnerable parts of rail track. The AE source location and noise cancellation were studied on the basis of practical rail profile, material and operational noise. In order to simulate the actual AE events of rail head cracks, field tests were carried out to acquire the AE waves induced by pencil lead break (PLB) and operational noise of the railway system. Wavelet transform (WT) was first utilized to investigate the time-frequency characteristics and dispersion phenomena of AE waves. Here, the optimal mother wavelet was selected by minimizing the Shannon entropy of wavelet coefficients. Regarding the obvious dispersion of AE waves propagating along the rail head and the high operational noise, the wavelet transform-based modal analysis location (WTMAL) method was then proposed to locate the AE sources (i.e. simulated cracks) respectively for the PLB-induced AE signals with and without operational noise. For those AE signals inundated with operational noise, the Hilbert transform (HT)-based noise cancellation method was employed to improve the signal-to-noise ratio (SNR). Finally, the experimental results demonstrated that the proposed crack detection strategy could locate PLB-simulated AE sources effectively in the rail head even at high operational noise level, highlighting its potential for field application.

• 한국철도학회논문집
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• 제7권3호
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• pp.264-270
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• 2004

The hub-and-spoke strategy is widely used in the field of transportation. At the field of rail transportation, however, it is difficult that we find an application case of this strategy because of modal characteristics. According to the fast growth of containerization and the development of transshipment technology, presently, the hub-and-spoke strategy is introduced by operators on actual European rail freight transportation. However, it is hardly to find empirical studies evaluating the applicability of transportation strategy. In this context, this study analyzed the applicabilities of hub-and-spoke strategy in the actual network of European rail freight. For the application and evaluation of the characteristics of hub-and-spoke strategy, it utilized a service network design model for rail freight. Utilizing this model, it analyzed the efficiency of furnished rail freight services, the potential locations of hubs, the characteristics of O-D flows by the types of trains and service links, and the types of paths of O-D flows. Finally, it proposed some implications and the further study topics.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.960-966
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• 2022

Mobility is an essential human need. Human survival and societal interaction depend on the ability to move people and goods. Efficient mobility systems are essential facilitators of economic development. Cities could not exist and global trade could not occur without systems to transport people and goods cheaply and efficiently. Rail has been considered as one of the important components of the transportation infrastructure required to service and improve the performance and productivity of an economy. In Nigeria, the rail infrastructure built by the colonial master several decades ago has been left in a state of total deterioration. This long neglect was occasioned by the failure of the government to pay adequate attention to infrastructure development. There is a vital and urgent need for rail infrastructure development in Nigeria. This study presents a systematic review of the evolution of rail, the current nature of railway infrastructure delivery in Nigeria, and offers possible suggestions on how to achieve an effective and sustainable rail infrastructure delivery in Nigeria. A thorough literature search of academic databases was conducted on current research trends on the subject of railway infrastructure by systematically reviewing selected published articles from reputable research domains. The analysis of the selected articles revealed the following among others (1) the existing railway infrastructure is in a state of mess and not sustainable, and (2), Government's investment/commitment in rail infrastructure seems inadequate compared to what is obtainable in other developed countries. Rail infrastructure development cannot be left to the Federal government of Nigeria to solve on its own; collaboration and participation are required. Government as a matter of priority should devote considerable attention to the development of rail infrastructure to harness the economic potential and transformation that sustainable rail infrastructural projects will provide.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1188-1195
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• 2007

The vertical forces in rail fasteners at areas of bridge transitions near the embankment and on the pier will occur due to different deformations of adjoining bridges caused by the trainloads, the settlement of supports, and the temperature gradients. The up-lifting forces is not large problem in the blast track because the elasticity of blast and rail pad buffs up-lifting effect. But, it is likely to be difficult to ensure the serviceability of the railway and the safety of the fastener in the end in that concrete slab track consist of rail, fastener, and track in a single body, delivering directly the up-lifting force to the fastener if the deck is bended because of various load cases, such as the end rotation of the overhang due to the vertical load, the bending of pier due to acceleration/braking force and temperature deviation, the settlement of embankment and pier, the temperature deviation of up-down deck and front-back pier, and the rail deformation due to wheel loads. The analysis of the rail fastener is made to verify the superposed tension forces in the rail fastener due to various load cases, temperature gradients and settlement of supports. The potential critical fasteners with the highest uplift forces are the fastener adjacent to the civil joint. The main influence factors are the geometry of the bridge such as, the beneath length of overhang, relative position of bridge bearing and fastener, deflection of bridge and the vertical spring stiffness of the fastener.

• 한국기계가공학회지
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• 제15권5호
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• pp.137-144
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• 2016

This paper aims to ensure describe the a spring-back prevention technique for improving shape fixability by using an ultra-high strength steel sheet with 980 MPa to develop a lightweight seat rail parts. Ultra-high strength steel gives a potential for considerable weight reduction and a cost-effective way to produce energy efficient vehicles. The influence of a spring-back of seat rail parts on the shape fixability in forming processes was investigated to be solved by an adjustment of the appropriate tool design and process parameters. The computed results for improving shape fixability were in good agreement with the experimental results.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1883-1895
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• 2007

With a land area of 910,768 sq. km, population estimate of 150 million people and GDP-growth rate of 6.9% per annum (2006 est), the centrality of effective public transportation in Nigeria is readily seen. In this regard, rail transportation offers much potential because of its relative safety, reliability, lower cost to the users and being singularly capable of transforming the national economy through mass movement of people, goods and services. Within this context, the demand for an effective railway system, and the enormous potentials for profitable investment in rail infrastructure in Nigeria, is indisputable. Beginning with the history, the paper discusses the main problems of Nigeria's railway transport system; and then makes policy suggestions, after considering the potentials of rebuilding the rail infrastructure. The necessity of this work is premised on the fact that there is a significant gap in critical knowledge about Nigeria's railway transport system.

• 한국철도학회논문집
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• 제16권5호
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• pp.439-446
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• 2013

한국 철도시스템의 해외진출을 위한 효과적 전략을 모색함에 있어 시장유형론적 접근이 필수적이다. 시장선택을 통하여 우선순위 시장을 선별하고 시장세분화를 통하여 각 하위시장의 특성에 적합한 마케팅 전략을 설계하여야 한다. 이를 위하여 본 연구는 글로벌 철도공급시장에 적합한 시장유망도 지표체계와 시장세분화 방안을 제시하였다. 아울러 시장유형론적 관점에서 최근 한국의 주요 철도기업이 추진하고 있는 수출유망 프로젝트를 분석하고 철도시스템 수출을 위한 전략적 시사점을 도출하였다.