• Journal of the Korean Society for Heat Treatment
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• v.11 no.1
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• pp.62-72
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• 1998

High carbon steel is used for rails due to the excellent wear resistance, however the welding of high carbon steel is more difficult than that of mild steel owing to the high hardenability and sensitivity to cracking at the weldment. In this study, the impact toughness and cracking behavior of a rail weldment were evaluated as function of preheating temperatures. Impact toughness were more excellent in the specimen welded with preheating temperature above $250^{\circ}C$ than that below $100^{\circ}C$, and cracks were not detected in the specimen welded with preheating temperature above $250^{\circ}C$.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.10
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• pp.993-1001
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• 2007

An analysis model has been developed to assess running safety of railway vehicle passing curves. By using ADAMS/Rail, a computer analysis has been conducted by changing various parameters according to the track conditions. Analysis results show as follows: A derailment coefficient of left wheel was increased according to increase of cant at low speed, while it was decreased as increase of cant at high speed. A unload rate of left wheel was also increased according to increase of cant at low speed, while it was decreased as increase of cant at high speed. A wear number of left wheel was increased according to increase of cant at all speed, but only at 35 m/s, it was decreased as increase of cant. A friction coefficient of left wheel was Increased according to increase of cant at all speed, but only at 35 m/s. it was decreased as increase of cant.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.318-325
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• 2005

In present, KTX's wheel is worn inevitably according to the interaction with rail in service. It was analyzed by wearing type, damage type and wheel reprofiling cycle on the running surface. As a result, damage on the running surface is main cause to reprofile the wheel. Wearing type of wheel is normal and it hasn't reprofiled according to normal wheel wear. As a follow-up result of the whee] defects on the running surface, if the defects size is well managed by periodical inspection, it would be efficient to increase the wheel life.

• Multiscale and Multiphysics Mechanics
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• v.1 no.3
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• pp.261-270
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• 2016

The longitudinal velocity (forward speed) having significant importance in proper running of railway wheelset on track, depends greatly upon the adhesion ratio and creep analysis by implementation of suitable dynamic system on contamination. The wet track condition causes slip and slide of vehicle on railway tracking, whereas high speed may also increase slip and skidding to severe wear and deterioration of mechanical parts. The basic aim of this research is to design appropriate model aimed estimator that can be used to control railway vehicle forward velocity to avoid slip. For the filtration of disturbance procured during running of vehicle, the kalman filter is applied to estimate the actual signal on preferered samples of creep co-efficient for observing the applied attitude of noise. Thus error level is detected on higher and lower co-efficient of creep to analyze adhesion to avoid slip and sliding. The skidding is usually occurred due to higher forward speed owing to procured disturbance. This paper guides to minimize the noise and error based upon creep coefficient.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.98-103
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• 2006

The hunting is the natural characteristics of the railway wheelset which is originated from the contact between the conical type wheel profile and rail. The critical speed of rolling-stock is called when the hunting is occurred, and it is closely connected with vehicle stability. The parameters which influence the hunting motion are like wheel profile, primary spring property and wheelset dimension, etc. The studies for these parameters are reported diversely. In this study, we aim to analyze the influence of parameters on hunting with the change of wheel profile produced by wheel wear and material property produce by aging of primary spring. For this, we made a dynamic model for wheelset and vehicle. Using these models, we analyzed the critical speed with the variations of the parameters like as wheel profile and primary spring property and we show the results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.175-181
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• 2016

This occurs when the unbalanced rotating body is inconsistent with the mass center line axis geometric center line. Wheelsets are assembled by a single axle with two wheels and a rotating body of a running railway vehicle. Owing to non-uniformity of the wheel material, the wear, and error of the wheel and axle assembly may cause an imbalance. Wheelsets will suffer the effects of vibrations due to the unbalanced mass, which becomes more pronounced due to the thin and high-speed rotation compared to the shaft diameter This can affect the driving safety and the running behavior of a rail car during high-speed running. Therefore, this study examined this unbalanced wheel using a railway vehicle multibody dynamics analysis tool to assess the impact of the dynamic VI-Rail movement of high-speed railway vehicles. Increasing the extent of wheel imbalance on the analysis confirmed that the critical speed of a railway vehicle bogie is reduced and the high-speed traveling dropped below the vehicle dynamic behaviour. Therefore, the adverse effects of the amount of a wheel imbalance on travel highlight the need for management of wheel imbalances. In addition, the static and dynamic management needs of a wheel imbalance need to be presented to the national rail vehicles operating agency.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.679-686
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• 2013

The reduction unit is one of the most important components in railway cars, due to the transmission of torque from the motor to the wheels. Faulty reduction gears in high-speed trains result from excessive wear on the gear or damage to the gear. These types of gear defects have a significant effect on high-speed rail operation and safety; thus, a diagnosis system for the reduction unit is needed. Vibration diagnosis technology is one of the most effective diagnostics. In this paper, the vibration parameters of a reduction unit were evaluated during a driving-gear test and a full-vehicle test, using kurtosis and the crest factor. These tests were performed under normal operating conditions; a specimen tester was used to diagnose problems in defective gears.

• Journal of the Korean Society for Railway
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• v.11 no.6
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• pp.524-529
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• 2008

The damaged wheel in railway vehicle would cause a poor ride comfort, a rise in the maintenance cost and even fracture of the wheel, which then leads to a tremendous social and economical cost. The defect initiation and crack propagation in wheel may result in the damage of the railway vehicle or derailment. Therefore, it is important to evaluate the characteristics of the wheel tread. In the present paper, the characteristics of wheel tread based on contact positions, running distance and brake pattern are evaluated. The result shows that the damaged wheel tread is remarkably depended on the contact positions between wheel and rail.

• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.91-98
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• 2011

Minimizing the cylinder wear and the consumption rate of cylinder oil in a large two-stroke diesel engine is of great economic importance. A motor-driven cylinder lubricator for Sulzer RT-flex large two-stroke diesel engines developed by authors is in need of mounting a quill system to lubricate cylinder parts for smoother operation. In order to apply the common-rail lubricating system to the developed cylinder lubricator as the second research stage, the quill system with a progressively quantitative distributor is improved in the electronically controlled quill system with an accumulating distributor. In this study, the effects of lubricator motor speed, plunger stroke and cylinder back pressure on oil feed rate, maximum discharge and delivery pressures are experimentally investigated by using the electronically controlled quill system with an accumulating distributor in the developed cylinder lubricator. It is found that the oil feed rate of the electronically controlled quill system with an accumulating distributor is larger than that of the quill system with a progressively quantitative distributor because of the increase of delivery speed and volume by changing the location of accumulator in the same experimental condition.