• International Journal of Railway
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• v.1 no.3
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• pp.83-88
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• 2008

Since the 1990's the fleet of the Dutch Railways showed a dramatic decrease in wheel tyre life. This lifetime reduction led to an unacceptable increase in life cycle costs. Therefore Lloyd's Register Rail has proposed to NedTrain to investigate the possibilities of improving the wheel tyre life. Three improvements were determined as most promising and relatively easy to achieve: - Profile optimisation for Rolling Contact Fatigue (RCF) reduction - a new wheel profile has been developed with a better resistance against rolling contact fatigue of the wheel tread. The profile has been implemented on single deck intercity trains and shows an increase in wheel tyre life of 30%. - Selection of improved wheel tyre materials - combining information from literature and experiences of manufacturers five alternative wheel tyre materials have been selected and are now being tested in practice. - Optimisation of the maintenance strategy - an alternative, preventative maintenance regime has been developed. With this Scraping regime, during short term maintenance every wheel is reprofiled. Higher mileages are reached and savings on life cycle costs up to 50% and more have been achieved. Unplanned maintenance goes down with $30{\sim}60%$. The results from field tests, using a reference group for comparison, and preliminary results after implementation show that the increase in wheel tyre life that is achieved with this project is significant. The results will continue to be monitored using the asset management tool 'Wheel Watch', that was specially developed for this project and is also described in this paper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.547-555
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• 2016

The wheel wear of a railway vehicle is mainly generated when maneuvering on a curved track. The change in the wheel profile affects the dynamic stability of the vehicle. In this analysis, the wheel wear volume was calculated while changing the velocity and radius of the curve to analyze the wear characteristics of a wheel at a curved section. The wear index was calculated from a vehicle dynamic analysis based on a multibody dynamics analysis and wear volume from a wear model by British Rail Research. The wear volume at a radius of 300 m is dominant compared with other radii. The wear volume was calculated by assigning different coefficients of friction to the tread and flange of the wheel to investigate the effect of lubrication on the wear characteristics. The effect of the improvement by lubrication is calculated by varying the radius of the track, and is assessed on an actual urban railway section.

• Journal of the Korean Society for Railway
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• v.2 no.2
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• pp.6-12
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• 1999

In this study, the most important suspension characteristics of railway vehicle, such as primary and secondary stiffness, are optimized to maximize ride qualify. Critical speed, secondary suspension stroke oil tangent track and derailment coefficient on the maximum curvature, are selected as the performance constraints. Piecewise linear curving model is used to evaluate derailment coefficient where it is assumed that wheel/rail contacts occurs at tread or at idealized flange. The combined design procedure is used to optimize above design variables at the same time.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.580-585
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• 2003

Korean high speed train (KHST) has adopted a combined electric/ mechanic (friction) braking system. Electric brakes are consist of rheostatic brake, regenerative brake and eddy current brake and mechanical brakes are composed of disc brake, wheel disc brake and tread brake. In this paper, we introduce the braking performance test and the measuring method of mechanical brake. And disc brake performance has been reviewed by the experimental method. The on-line test of KHST has been carried out up to 260 km/h and proved that the disc braking capacity of KHST is sufficient.

• Journal of Sensor Science and Technology
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• v.13 no.3
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• pp.244-251
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• 2004

In general, the braking system of high speed train has an important role for the safety of the train. To stop safely the train at its pre-decided position, it is necessary to combine properly the various brakes. Korean high speed train (HSR 350x) has adopted a combined electric and mechanic (friction) braking system. Electric brakes are consist of rheostatic brake, regenerative brake and eddy current brake and mechanical brakes are composed of disc brake, wheel disc brake and tread brake. In this paper, the measuring method that can take a measurement of the braking forces for disc brake and wheel disc brake has been suggested and we have verified that this method is valid through on-line test of HSR 350x.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.12
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• pp.1237-1244
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• 2016

Vehicle classification system in domestic tollgates is usually to use treadle sensor for calculating wheel width and tread of the vehicle. Due to the impact that occurs when the wheels of the vehicle contact, treadle sensor requires high durability. Recently, KHC(Korea Highway Corporation) began operating high-speed lane for cargo truck. High-speed cargo truck generate more impact the design criteria of previous treadle. Therefore, an increase in the maintenance and management costs of the treadle damage is concerned. In this paper, we propose an algorithm to classify vehicles using non-contact treadle sensors for improving durability from physical impacts. This was based on the KHC's classification criteria and showed a classification accuracy of 99.5 % in one experiment with 1892 vehicles through Changwon tollgate in 1020 local road. Therefore, it shows that vehicle classification system using non-contact treadle sensor could be applied to domestic toll tollgates, effectively.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.805-810
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• 2004

The model is verified thorough simulations and experiments. And then the developed model is applied to a half car model and automobile vibrations are analyzed. The effects of tire design parameters on the automobile vibration energy are investigated. The results from laboratory and field tests confirm the validity of the analytical model. The 17-DOF half-car model is built to analyze the automobile vibration. The characteristics of the nonlinear model for a shock absorber are applied to this model. The results from the present 17-DOF half car model incorporating the analytical tire model with tire design parameters, are compared with a 5-DOF half car model where the tire is modeled with linear springs. The results of the 17-DOF model are closed to experimental results. Using the 17-DOF model, the influences of tire design parameter are considered. According to the results of analyses, the vibrations at seat/body/wheel are predicted by simulation and experiment.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.171-182
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• 2003

Tire vibration modes are known to play a key role in vehicle ride and comfort characteristics. Inputs to the tire such as impacts, rough road surface, tire nonuniformities, and tread patterns can potentially excite tire vibration. In this study, experimental modal analysis on the tire in ground contact are performed by a 3-D impact at the center of contact patch to investigate which modes of tire influence the vibration of wheel and axle. Through the experiment, the vibration transmission properties from tire to axle are examined. And we have compared the influential tire modes when the tire is excited by a vertical impact with those when excited by the 3-D impact. Additionally, the modes of ground contact tire are compared with those of the suspended tire.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.483-488
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• 2001

As the technique of automobile industry is being advanced, the advancement of vehicle ride is being required. In order to achieve this purpose, the study on the vibration which are produced by moving vehicle is carried out actively. In this study, the tire vibration characteristics for passing over a cleat are analyzed. The model is verified against simulations and experiments. The tire is modeled with 7-DOFs (degree of freedom), and the effects of changing tire design parameters are considered. According to the results of analysis, the design parameters that reduce the tire and wheel vibration energy are conducted.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.212-217
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• 2004

In general, the braking system of high speed train has an important role for the safety of the train. To stop safely train at its pre-decided position, it is necessary to combine properly the various brakes. The prototype of Korean high speed train (KHST) has been designed, fabricated and tested by the domestic researchers. It has adopted a combined electrical brakes, such as rheostatic brake, regenerative brake and eddy current brake, and mechanical brakes composed of disc brake, wheel disc brake and tread brake. In this paper, the performances and control algorithms of braking system have been reviewed by the experimental method.