| 요약2 |
In recently, numbers of civil appeal about railroad noise are growing due to the deterioration railroad noise barrier walls. The regulation of sound barrier wall used sound absorption coefficient of sound proof panels must apply the average of sound absorption coefficient in four frequency ranges (250,500,1000,2000㎐). In the measurement , the regulation of sound absorption coefficient is satisfactory when the average value of sound absorption coefficient is over 0.7. However after installation of noise barrier wall, it isn't know whether the performances of noise barrier walls are good or bad because of being not a management regulation of noise barrier wall. So in this study, the measurements of sound absorption coefficient and investigate on the present condition of noise barrier walls were carried out in the field and laboratory. As the results, the number of problem on the noise barrier wall were found out. According to the deterioration, a damaged part and bending problem and crack and deterioration of sound absorption material has appeared in the noise barrier wall. Particularly sound absorption coefficient of over 1㎑ frequency ranges were measured 0.8-0.52. It seemed to be clogged with the dust in the absorption material. So it is expected that the management regulation of railroad noise barrier wall is needed. |