• Proceedings of the KSR Conference
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• 2009.05a
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• pp.659-666
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• 2009

As the density and height of the buildings nearby subway lines get higher, the unprecedented residents' appeals for noise are on the rise. Furthermore, in accordance with the revision of enforcement regulations on the Noise and Vibration Control Act, the night time noise standards have been reinforced by 5dB effective on January 1st 2010 and the appropriate measures shall be taken accordingly. For the settlement of the public grievances against noise and vibration generated on tracks in at-grade and elevated section, the installation of continuously-welded-rail, rail lubrication system, improved fastening system and higher noise barrier is currently executed. Nevertheless, the noise and vibration levels in some areas are still exceeding the limits required in the regulation. Among the measures, an installation of higher noise barrier or noise tunnel seems to be the most effective way; however, it has limitations owing to the structural stability of existing elevated structures. The paper in consideration of the local conditions and foreign practices discusses the installation of fairing system under the train body as an noise insulation panel in order to reduce the rolling noise and under-carriage noise. Based on the result of this study, a performance verification test during actual train operation is in progress for further study.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.212-222
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• 2015

The characteristics of noise emission from tram systems should be investigated in order to design and construct an urban tram network that raises fewer environmental noise problems. In this paper, the characteristics of rolling noise from a tram were studied and a desired stiffness of the rail supports was proposed using a noise prediction model. The mobilities of embedded rails and resilient wheels were predicted using the Timoshenko beam model and the finite element model, respectively. The predicted mobilities were compared with the measured results. Compared with the measured values, the calculated noise level near the track showed small errors for frequencies higher than 300 Hz. Then, the source strengths of rail and wheel components were examined by varying the rail supporting stiffness and the slab supporting stiffness so that suitable stiffness values could be estimated that would reduce noise radiated from rails and wheels but that would not greatly increase the ground vibration.

• Structural Engineering and Mechanics
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• v.75 no.4
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• pp.507-518
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• 2020

With the rapid development of rail transit, rail transit noise needs to be paid more and more attention. In order to accurately and effectively analyze the characteristics of low-frequency noise, a prediction model of vibration of box girder was established based on the hybrid FE-SEA method. When the train speed is 140 km/h, 200 km/h and 250 km/h, the vibration and noise of the box girder induced by the vertical wheel-rail interaction in the frequency range of 20-500 Hz are analyzed. Detailed analysis of the energy level, sound pressure contribution, modal analysis and vibration loss power of each slab at the operating speed of 140 km /h. The results show that: (1) When the train runs at a speed of 140km/h, the roof contributes more to the sound pressure at the far sound field point. Analyzing the frequency range from 20 to 500 Hz: The top plate plays a very important role in controlling sound pressure, contributing up to 70% of the sound pressure at peak frequencies. (2) When the train is traveling at various speeds, the maximum amplitude of structural vibration and noise generated by the viaduct occurs at 50 Hz. The vibration acceleration of the box beam at the far field point and near field point is mainly concentrated in the frequency range of 31.5-100 Hz, which is consistent with the dominant frequency band of wheel-rail force. Therefore, the main frequency of reducing the vibration and noise of the box beam is 31.5-100 Hz. (3) The vibration energy level and sound pressure level of the box bridge at different speeds are basically the same. The laws of vibration energy and sound pressure follow the rules below: web

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.446-454
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• 2011

The noise of the subway has become a social issue and includes very complex reasons. The friction between rail and train wheel is the most important reason of the noise. In this study, we developed MFI(Multi Fluid Injection) System which sprays the mixed fluid(water, anticorrosive and lubricant) on the rail when the train is approaching to reduce the friction. To verify the system's effect, we measured the internal and external noise of the running train. The measured and analyzed results show that MFI system reduce the noise of the running subway.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2934-2940
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• 2011

The railway system in Korea is developing more and more rapidly. After development the next generation hi-speed train(HEMU-400X), Korea can compete against developed country. But, speed increasing will cause the greater rolling and aero dynamic noise. In this study shows that measurement noise of the KTX train by 300kn/h class, and KTX-Sancheon train by 350km/h class. The measurements are carried out on open area and noise protection barrier installed area. The microphones were placed at a distance of 3m from the center line of the track at a height of 0.5m above the upper surface of the rail and at a distance of 7.5m from the center line of the track at a height of each 0.6m above(Max 3.6m) the upper surface of the rail. One microphone was placed at a distance of 25m for check the environmental noise.

• Smart Structures and Systems
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• v.23 no.4
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• pp.347-357
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• 2019

A new methodology for mitigation of the wheel squealing is proposed and investigated based on the dithering control. The idea can be applied in railway lines particularly in urban areas. The idea is clearly presented, and applied to a validated model. A full-scale model including the vehicle, curved track and wheel/rail contact is developed in the time domain to analyze the possibility and level of wheel squeal noise. Comparing the numerical results with a field test, the model is validated in different levels namely i) occurrence, ii) squealing frequency and iii) noise level. Two different approaches are proposed a) dithering of the wheel with piezoelectric patches and b) dithering of the rail with piezoelectric stacks. The noise level as well as the wheel responses is compared after applying the control strategy. A parametric study is carried out and effect of the dithering voltage and frequency on the squealing noise is investigated. It is found that both the strategies perform quite effectively within the saturating threshold of piezoelectric actuators.

• Journal of Environmental Impact Assessment
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• v.15 no.6
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• pp.453-458
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• 2006

A turnout system which permits trains to pass from one track to another consists of the switch, the crossing, lead rails which are necessary to connect the switch and the crossing, two guard rails and a switch machine for operating the switch. A turnout is the sole moving part among the railway components and has complex configuration, so the safety has always been raised an issue. In Korea, it is planned to adopt the high speed tilting train, which operates at the maximum speed of 180km/h, at conventional lines by the year of 2010. However, for the application of the tilting train to conventional lines, it is prerequisite to establish a stable turnout system allowing the tilting train to pass through it without reducing speed. Therefore, the improved turnout system for the speed-up of conventional lines has been developed and the prototype of the turnout system has been constructed. In this study, evaluation of noise characteristics around the improved turnout system was performed through the field measurements. Field measurements of noise around the conventional and the high-speed turnout system were also carried out for the comparison.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.585-588
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• 2004

In this study, Curve dependent wheel flange lubricator with grease spray type is investigated and estimated a point of view reducing wheel flange wear and noise in the curve through field test on korean rail. Advantage of curve dependent wheel flange lubricator with grease spray type is found on the basis of the result of field test in comparison with oil spray type lubricator and wheel without wheel flange lubricator on railroad in Korea.

• Journal of KSNVE
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• v.8 no.4
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• pp.616-622
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• 1998

An analytical method has been developed to estimate the dynamic contact force between wheel and rail when trains are running on rail with vertical irregularities. In this method, the effect of Hertzian deformation at the contact point is considered as a linearized spring and the wheel is considered as an sprung mass. The rail is modelled as a discretely-supported Timoshenko beam, and the periodic structure theory was adopted to obtain the driving-point receptance. As an example, the dynamic contact force for a typical wheel/rail system was analysed by the method developed in this research and the dynamic characteristics of the system was also discussed. It is revealed that discretely-supported Timoshenko beam model should be used instead of the previously used continuously-supported model or discretelysupported Euler beam model, for the frequency range above several hundred hertz.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.10
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• pp.758-765
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• 2002

KITECH and ODS performed a study of internal and external noise prediction of the Korean high speed prototype test train(HSR 350X). The object of this study was 3 kinds of cars, trailer car(TT2), motorized car(TMI ) and power car(TPI) and the predicted noise was for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from manufactures. Some of noise sources which were not available in the project team, were chosen by experiences of ODS. Internal noise level of each car was predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated for each section of the car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is the (floor in terms of structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TMI are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TMI are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.