• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.165-172
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• 2017

High frequency squeal noise can be generated when a railroad vehicle runs a sharp curved section; this noise causes environmental complaints and excessive wear on the wheel and the railroad track. In this paper, curved squeal noise experiments on a commercial railway were carried out to investigate this phenomenon. The relationship of the squeal noise pressure level, the frequency characteristics, the railway running speed, and the modal behavior of the wheel were investigated. At the same time, the lateral motion of the wheel relative to the rail was captured using a video camera; wheel movement was calculated when the noise was generated. queal noise occurred at the highest level at the inner front wheel; this phenomena is considered to be related to the lateral vibration response characteristics of the wheel. It can be seen that the magnitude of this squeal noise is not directly related to the increase in vehicle speed.

• Journal of the Korean Society for Railway
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• v.6 no.3
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• pp.209-214
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• 2003

When a rail vehicle transverses tight curves, it often emits an intense, high-pitched squeal. This squeal has always been noticed as one of the most disturbing noise sources of railway systems. At present, we cannot predict squeal noise that is influenced by a large number of dependent parameters. In this study, we performed structural analysis to find out the frequency of the wheel and measured squeal noise at Seoul subway. We also tested reduction effectiveness of squeal noise through rail lubricator.

• Journal of the Korean Society for Railway
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• v.2 no.2
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• pp.31-38
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• 1999

Two representative types of the AGT (Automated Guideway Transit) system, which are bogie and steering types, are available for the side-guided system. Each system primarily consists of the bogie frame, suspensions, wheelsets and axles, braking system and transmission system. Among these components, the bogie frame is one of the most significant components subjected to the whole vehicle and passenger loads. This paper describes structural analyses and associated fatigue analyses for each bogie frame depending on the various loading conditions on a basis of the railway vehicle code UIC 515-4. Subsequently, comparisons are made between those two types to estimate which type is more reliable in terms of strength and fatigue. It is observed that the bogie type is a little advantageous over the steering one from the strength analysis. However, the two types are found to be in a reliable range of fatigue even though a realistic fatigue load case is further carried out. In addition, an optimal size of thickness is suggested for designs of the bogie frame.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.43-52
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• 2010

In this study, the shapes of the wheel and rail are represented by using 3-dimensional surface functions with surface parameters and a 3-dimensional wheel-rail contact analysis is presented. A whole numerical solution of wheel-rail contact at tread and flange including 2-point contacts can be achieved with the proposed numerical algorithm. Kinematic characteristics such as variances of vertical displacement and roll angle, and variance of wheel radius difference for arbitrary yaw and lateral displacement of wheelset, are determined for the KTX wheel-rail pair as an example. The condition of yaw and lateral displacement occurring 2-point contacts to analyze derailment are compared between standard and worn wheels. Differences of contact characteristics between curved and straight rails are also analyzed.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.529-538
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• 2009

A trial run of locally-developed tilting train has been in process on Chungbuk line since the test vehicle was first produced. For the system stabilization, interface verification among the systems including track, structure, catenary and signaling system, not to mention the rolling stock, is very crucial. Therefore, in this study, the dynamic rail force of the tilting (Hanvit 200), high-speed (KTX) and general (Mugunghwa) vehicle caused by driving in transition curve track was measured. And, it compared the tilting response with the other by using the measured wheel load data in transition curve track, and then evaluated probability the range of wheel load fluctuation for the variable dynamic vertical and lateral wheel load. As a result, a range of wheel load by occured a change of cant from the high-speed and general vehicle which had fixed bogie structure was distributed throughout small deviation (${\Delta}8{\sim}13kN$). Otherwise, in case of the tilting train which was consisted of the pendulum bogie structure was distributed wide range about large deviation (${\Delta}25{\sim}28kN$) by changed of cant.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.201-207
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• 2003

Sensitivity analysis of suspension elements of an articulated bogie for light railway vehicles is presented. The ride, stability and safety are used as dynamic performance indices. Suspension elements of 10 and a conicity of wheel are used as design variables. To analyze sensitivity of design variables. the railway vehicle dynamics analysis program AGEM is used. The results show that the secondary suspension elements have a strong effect on ride and the primary suspension elements have a moderate effect on ride. Conicity of wheel has a strong effect on the stability. The safety is not effected by all the design variables.

• Journal of the Korean Society of Safety
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• v.38 no.4
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• pp.1-7
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• 2023

The steel wheels of urban railway vehicles gather a lot of data through regular measurements during maintenance. However, limited research has been carried out utilizing this data, resulting in difficulties predicting the maintenance period. This paper studied a machine learning model suitable for mileage prediction by studying the characteristics of mileage change according to diameter and flange thickness changes. The results of this study indicate that the larger the diameter, the longer the travel distance, and the longest flange thickness is at 30 mm, which gradually shortened at other times. As a result of research on the machine learning prediction model, it was confirmed that the random forest model is the optimal model with a high coefficient of determination and a low root mean square error.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.773-778
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• 2008

The subway noise in curved line is affected not only by rail condition but also wheel condition and dynamic characteristics. The railway curving noise can be divided into 2 categories. The first is noise depending on the vehicle speed, and the second is the one independent on vehicle speed. In this study the noises were reviewed by using eigen-mode of wheel and waterfall plot which shows noise level in time-frequency domain. And also those were reviewed in viewpoint of stick-slip noise and wheel flange contact noise.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.7
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• pp.541-549
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• 2016

Rolling contact fatigue and wear on rails are inevitable in railway operations due to excessive wheel-rail contact stress. The wear is influenced by vehicle speed, contact pressure, environmental conditions, and many other factors. Speeding on a curved track causes many problems such as wear on the gauge of the rail and rolling contact fatigue. Managing environmental conditions can reduce problems on the wheel and rail interface. In this study, the wear characteristics of wheel and rail materials were investigated by twin-disc testing using various parameters. The results of the wear test indicated that the wear rate under dry conditions was larger than that under wet conditions. We found that contact fatigue damage occurred on the rail in dry conditions, however, the surface of the specimen under water remained smooth. Also, the friction coefficient in dry conditions was larger than in wet conditions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.30-37
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• 2017

When a wheel profile of a train-tram is designed, both train and tram tracks should be considered. This study designed a wheel profile that enables high-speed driving(200km/h) on the train track and low speed driving on the tram track with multiple sharp curves. The study used the approximation optimization method to reduce cost and time, used the sequential quadratic programming method as the optimized algorithm, and the central composite design and response surface method as an approximate model. The optimized wheel shape based on this approximation optimization method reduced wear of the initial wheel showed a better performance in terms of derailment and lateral force.