• Wind and Structures
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• v.35 no.3
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• pp.177-191
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• 2022

Trains emerging on a streamlined bridge-girder may have salient interference effects on the aerodynamic properties of the bridge. The present paper aims at investigating these interferences by wind tunnel measurements, covering surface pressure distributions, near wake profiles, and flow visualizations. Experimental results show that the above interferences can be categorized into two primary effects, i.e., an additional angle of attack (AoA) and an enhancement in flow separation. The additional AoA effect is demonstrated by the upward-moved stagnation point of the oncoming flow, the up-shifted global symmetrical axis of flow around the bridge-girder, and the clockwise-deflected orientation of flow approaching the bridge-girder. Due to this additional AoA effect, the two critical AoAs, where flow around the bridge-girder transits from trailing-edge vortex shedding (TEVS) to impinging leading-edge vortices (ILEV) and from ILEV to leading-edge vortex shedding (LEVS) of the bridge-girder are increased by 4° with respect to the same bridge-girder without trains. On the other hand, the underlying flow physics of the enhancement in flow separation is the large-scale vortices shedding from trains instead of TEVS, ILEV, and LEVS governed the upper half bridge-girder without trains in different ranges of AoA. Because of this enhancement, the mean lift and moment force coefficients, all the three fluctuating force coefficients (drag, lift, and moment), and the aerodynamic span-wise correlation of the bridge-girder are more significant than those without trains.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.715-720
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• 2002

The dynamic load effects, generated by moving trains, are transferred to the railway bridges through tracks. The dynamic load effects may vary due to the dynamic characteristics of the applied vehicle loads and the railway bridges including the track system. However, the track models have been neglected or simplified by spring elements in the most studies since it is quite complicated to consider the track systems in the dynamic analysis models of railway bridges. In this study track system on railway bridges are modeled using a three-dimensional discrete-support model that can simulate the load carrying behavior of tracks. A 40m simply supported prestressed concrete box-girder system adopted for high-speed railway bridges are modeled for simulation works. The train models are composed of 20 cars for KTX. The dynamic response of railway bridges are found to be affected depending on whether the track model is considered for not. The influencing rate depends on the traveling speed and different wheel-axle distance. The dynamic bridge response decreases remarkably by the track systems around the resonant frequency. Therefore, the resonance effect can be reduced by modifying the track properties in the railway bridge, especially for KTX trains.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1581-1587
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• 2004

This study investigates the major railway firms in the world in the perspectives of organization, financing structure, business fields, and strategies. The analysis gives us some implication of how railway system, in particular, high speed trains developed in Korea go aborad.

• International Journal of Railway
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• v.5 no.3
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• pp.114-116
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• 2012

The technology of high-temperature superconductive (HTSC) maglev trains has become mature and ready for a commercial use ten years after its first prototype was made by Jiasu Wang and Suyu Wang. However, an appropriate roadmap in applying it to the market is crucial for its success because superconductivity mystery remains veiled and public safety concern may prevent it from being used.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.422-428
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• 2001

This paper provides a brief overview of the process for the introduction of new train in England since privatization in 1994. They have railway safety case which the safety management for the introduction of new trains is to be considered in all process including design, manufacturing, test, maintenance etc. To achieve safety in track, they also consider evidence available from the design and build process.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.450-457
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• 1999

In this study, the simplified method for 3-dimensional vehicle-bridge interaction analysis is utilized in the analysis of dynamic behavior of bridges in which the eccentricity of axle loads and the effect of the torsional forces acting on the bridge are included for the more accurate vehicle-bridge interaction analysis. Investigations mainly into the influence of vehicle speed on vehicle-bridge interactions are carried out for case that two trains move respectively on their tracks in the opposite direction.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.387-392
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• 2004

There has been an increasing demand for the noise impact assessment by the high-speed trains due to the expansion of high-speed rails. This paper provides procedures for the evaluation and the assessment of the potential noise impact resulting from proposed high-speed rails. Firstly the official specifications for the railway noise have been reviewed, and the procedures for the initial noise evaluation and the detailed noise analysis have been described.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.316-323
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• 2000

In railway train operations, a braking distance between two trains must be controlled on their speeds to avoid rear end collisions. The distance is decided by some parameters such that propulsion and braking performance of trains, gradient and etc. When determining this block distance, it is important to consider the two aspects that safety insurance at train running and increase of train running frequency. In this paper, we showed a methodologies of equiblock by consideration gradients and calculated optimal block speeds on the basis of the equivalent block distance.

• Journal of the Korean Society for Railway
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• v.7 no.3
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• pp.208-214
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• 2004

In this paper, traction system and electric devices of a double deck train were designed to examine technical reasonableness for driving on the ground and underground. Double deck trains operated in other countries were also considered. For designing the electric devices, two types of accelerations and electric devices arrangements which are based on the current subway system were considered.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.2
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• pp.61-68
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• 2024

The majority of high-speed railway bridges along the domestic Gyeongbu and Honam lines feature a PSC-box type structure with a span length ranging from 35 to 40m, which typically exhibits a first bending natural frequency of approximately 4 to 5Hz. When KTX high-speed trains transverse these bridges at speeds ranging from 290 to 310km/h, the vibration induced by the trains approaches the first bending natural frequency of the bridge. Furthermore, with the upcoming operation of a EMU-320 high-speed train and the anticipated increase in the speeds of these high-speed trains, there is a need to analyze the dynamic response of high-speed railway bridges. For this, based on measured responses from actual railway bridges, a numerical model was constructed using a numerical model updating technique. The dynamic response of the updated numerical model exhibited a strong agreement with the measured response from the actual railway bridges. Subsequently, this updated model was utilized to analyze the dynamic response characteristics of the bridges when KTX and EMU-320 trains operate at increased speeds. The maximum vertical displacement and acceleration at the mid-span of the bridges were also compared to those specified in the railway design standard with the increasing speed of KTX and EMU-320.