Abstract
Korean high-speed trains with the maximum speed of 300 km/h have started revenue services since April 2004. A large portion of the "Kyung-Bu" line is comprised of tunnels or bridges, which may cause excessive noise in a vehicle. During the process of the site acceptance test it was unable to satisfy some of the requirements for the noise test. Hence, the test procedure for the interior noise measurement of KTX trains are reviewed and investigated with the reference of international standards. The vibration generated by the trains propagates into the structure of the tunnel and the vehicle and it can be radiated as noise inside the vehicle interior. This noise can usually be heard as low frequency structure-borne noise. Measurement of the noise and vibration inside the Korea Train Express (KTX) vehicle confirmed that the noise comprises of frequencies below 250 Hz with a couple of broad peaks. In this study the analysis has been presented to reveal the cause of the excessive noise level and the correlation between the vehicle interior noise and the vibration of the tunnel structure. A remarkable aspect of the frequency spectra is the peak in the low frequency region. The acceleration level of the sleeper in a ballasted track is much higher because it's motion is relatively free compared to that of a slab track. Finally, a reduction method of interior noise of KTX in tunnels. The study was also intended to investigate fluctuation of pressure in a tunnel as one of interactions between a vehicle and a tunnel. To from a test vehicle with the existing mud-flap and another one with the new one. It was shown that mud-flap used in this study reduced the interior noise of KTX vehicle effectively while it is running on slab bed in a tunnel.
