• Journal of the Korean Society for Railway
• /
• v.9 no.5 s.36
• /
• pp.550-554
• /
• 2006

In the early stage of operation of KTX, passengers complained of the excessive cabin noise as the passes the tunnel. The noise is caused partly by wheel-rail contact and partly by airflow around the carbody. In this study, to reduce the cabin noise, the effect of the mud-flaps located between the cars is investigated. A series of tests was conducted to clarify the influences of the type and length of mud-flap, and train speed on the cabin noise. The optimum length of mud-flap was found. The shedding vortices around the mud-flap is thought to be the cause of the aerodynamic noise. Strouhal number and the resonant shedding frequency around the mud-flap correlated well with the cabin noise level.

• Journal of Power System Engineering
• /
• v.14 no.5
• /
• pp.56-62
• /
• 2010

In this paper, a recurrent cerebellar modulation articulation control (RCMAC) has been developed for improvement of noise attenuation performance in active noise control system. For the narrow band noise, a filter-x least mean square (FXLMS) method has bee frequently employed as an algorithm for active noise control (ANC) and has a partial satisfactory noise attenuation performance. However, noise attenuation performance of an ANC system with FXLMS method is poor for broad band noise and nonlinear path since it has linear filtering structure. Thus, an ANC system using RCMAC is proposed to improve this problem. Some simulations in duct system using harmonic motor noise and KTX cabin noise as a noise source were executed. It is shown that satisfactory noise attenuation performance can be obtained.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.10
• /
• pp.1900-1907
• /
• 2010

In this paper, a recurrent cerebellar modulation articulation control with praticle swarm optimization (PSO) method has been investigated for improvement of noise attenuation performance in active noise control system. For narrow band noise, FXLMS and RCMAC has a partial satisfactory noise attenuation. However, noise attenuation performance is poor for broad band noise and nonlinear path since it has linear filter structure. To improve this problem, a RCMAC with PSO is proposed and it is shown that satisfactory noise attenuation performance is obtained by some simulations in duct system using harmonic motor noise and KTX cabin noise as a noise source.

• Proceedings of the KSR Conference
• /
• 2003.10c
• /
• pp.120-125
• /
• 2003

Since May 2003, On-line test to validate the interface between electrified conventional track, rolling stock, power supply and signalling system. Main test items are the suitability of the system such as vibration of the rolling stock, noise, current collection, track and signal system. In this article, part of the vibration and noise related test results are introduced such as the vibration of the carbody and bogie, running stability, jerk, interior noise of the passenger car and driver's cabin.

• Journal of the Korean Society for Railway
• /
• v.10 no.6
• /
• pp.786-791
• /
• 2007

Aerodynamically generated noise is dominant when the train speed approaches 300km/h. This noise sources is caused by the turbulent flow separations or vortex shedding from the train structure. Experiments were performed to investigate the characteristics of aerodynamic noise sources generated from exterior of the KTX trains and HSR-350x, especially from the inter-coach spacing. Measurements of both the inside and outside of the cabin are carried out to investigate the characteristics of the noise. Effect of the size of the mud-flap has been investigated through an wind tunnel test and it has been found that the low frequency noise is strongly dependent on the size of the gap. Also performed is an array measurement to locate different noise sources from the high-speed train. spectral characteristics of exterior noise sources are examined.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.6
• /
• pp.431-436
• /
• 2002

The interior sound pressure level of the Korean high-speed train(KHST) is predicted by geometrical acoustic method. For the Purpose of assuring the prediction of Interior noise of KHST by the geometrical acoustic scheme, calculated sound level values of the Korean train express(KTX) by Identical geometrical method are compared with measured values of KTX prototype vehicle by experiment. Contribution of individual sound source of KHST vehicle Into the interior response positions is calculated and sound sources are classified in influential order. Hence, it is reasonable approach to reduce sound power of most contributing noise source first. Sensitivity of the interior response position's sound pressure level (SPL) with respect to train wall sections' transmission loss are carried on and acoustically sensitive spot is identified, for example window area for passenger cabin case. Those contribution and sensitivity analysis results are suggested to design quieter train efficiently.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.1093-1098
• /
• 2001

The interior sound pressure level of the Korean high speed train is predicted using ray acoustic method. The motor car, motorized car and passenger cabin are investigated under the environment of passing open countryside and inside tunnel Calculated sound levels of KHST are compared with the those of KTX prototype which vehicle shows similar acoustic behavior with KHST for the purpose of assuring the calculated data. In order to reduce the calculated SPL in systematic way, contribution analysis of sound sources and sensitivity analysis of concerning wall's transmission loss on the SPL of the designated receiving points are carried out. Finally, practical design suggestions are proposed.

• The KSFM Journal of Fluid Machinery
• /
• v.17 no.5
• /
• pp.54-59
• /
• 2014

The new high speed combi train prototype project was developed which named HSB. It runs over the speed of 330km/h. As the speed of the train exceeds over 300km/h, due to pressure change in tunnel, aerodynamic problems such as sudden drag increase, severe acoustic noise, passenger discomfort and tunnel pressure sonic boom were occurred. This aerodynamic characteristics in tunnel should be reviewed in early design state to enhance the performance and driving quality of new high speed train. In this paper, the aerodynamic characteristics in tunnel for HSB such as pressure waves in tunnel, a rate of pressure change in cabin and micro pressure wave that cause sonic boom outside tunnel are analyzed by 2D axisymmetric CFD simulations. The results are also compared with the value for ordinary high speed train like the KTX-Sancheon. It is helpful how to design the configuration of HSB train. Finally it shows that the HSB train was well designed in tunnel condition because all values fulfill the criterions on UIC code and Korean national regulations.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.1227-1232
• /
• 2008

High-speed train of push-pull type called as G7 train has been developed and chosen as the model of KTX-II which will be operated on Honam Line nexr year. However, the EMU-type high-speed train appeared to be the recent trend that foreign markets have shown. Also, in the near future, a great number of new train sets are needed to accommodate the increased passengers in our country. Thus, development of the high-speed EMU was decided, planned, and started. In the development, included were almost all fundamental key technologies such as noise and vibration reduction in a passenger cabin, running characteristics, aerodynamic analysis, crashworthiness evaluation, EMI/EMC analysis, design of the cooling system for the propulsion control system, enhanced performance of transformer and switching converters, synchronous traction motor with permanent magnets, new design of front nose and ergonomic interiors, application of advanced information technology(IT) and smart sensors and the cost reduction of construction of railway bridges, etc. Each key technologies are carried out as sub-project independently but under the supervision of a project. The project will develop the high advanced level of technologies and provide necessary know-why's and support the team in charge of the development of the high-speed EMU, Hyundai Rotem Co. Ltd. The high-speed EMU will be successfully developed with the support of the project.

• The Journal of the Acoustical Society of Korea
• /
• v.37 no.4
• /
• pp.223-231
• /
• 2018

Recently, due to various environmental problems, blast tracks in tunnel are replaced with concrete tracks, but they have more adverse effects on noise than blast tracks so that additional noise measures are needed. Among these measures, sound-absorbing blocks start to be used due to its easy and quick installation. However, the performance of sound absorption blocks need to be verified under real environmental and operational conditions. In this paper, interior noise levels in KTX train cruising in Dalseong tunnel are measured before and after the installation of sound-absorbing blocks and the measured data are analyzed and compared. Additionally, noise reduction are estimated by modeling the high speed train, the tunnel and absorption blocks. Measurement devices and methods are used according to ISO 3381 and the equivalent sound pressure levels during the cruising time inside the tunnel are computed. In addition to overall SPLs(Sound Pressure Levels), 1/3-octave-band levels are also analyzed to account for the frequency characteristics of sound absorption and equipment noise in a cabin. In addition, to consider the effects of train cruising speeds and environmental conditions on the measurements, the measured data are corrected by using those measured during the train-passing through the tunnels located before and behind the Dalseong tunnel. Analysis of measured results showed that the maximum noise reduction of 6.8 dB (A) can be achieved for the local region where the sound-absorbing blocks are installed. Finally, through the comparison of predicted 1/3-octave band SPLs for the KTX interior noise with the measurements, the understanding of noise reduction mechanism due to sound-absorbing blocks is enhanced.