• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1355-1359
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• 2000

In this study, the insertion losses of various track-side railway noise barriers are analyzed by using a two-dimensional numerical boundary element method(BEM). The BEM is implemented using two out-of-phase monopole sources for each track to represent dipole source. All model for this study is based on actual size built in Test Line of KTX. And the results suggest that vertical absorptive barrier provide as effective screening as rigid barrier which is more 0.4 m than the height of those.

• The Journal of the Acoustical Society of Korea
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• v.21 no.7
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• pp.624-631
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• 2002

The insertion loss of the noise barriers with several top shape is measured in an anechoic room by using a reduced scale model test. The insertion loss differences between a straight vertical barrier having 0.3 m height and several barriers with simple top shaped are compared. The results show that the latter is more effective than the former and absorptive barrier is more effective than the reflective one. Among the barrier types of 'T', 'Y', and '(equation omitted)', type 'Y' is the best one and the rest have similar effect. This result is well agree with Alfredson (PIOC. Inter-Noise 95, p. 381, 1995)'s but contradict to May (J. Sound Vb. 71, p. 73, 1980)'s. Therefore, it is difficult to determine which type is the best. In order to find out this discrepancy, boundary element method is adopted and the result shows one can have different result because each supposed different experimental conditions like height of noise barrier, positions of sound source and receiver, etc.

• The Journal of the Acoustical Society of Korea
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• v.35 no.3
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• pp.223-233
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• 2016

Design of a vegetation type sound barrier was presented as a noise barrier on the boundary of neighborhood facilities including schools, and apartments. The suggested noise barrier is made of unit blocks that are to be formed by stacking over the wall structure containing the plant and soils in the blocks. The advantage of the vegetation noise barrier is to acquire not only sound absorptive effects of plants and soils, but also sound diffusive effect caused by the irregular surface of the barrier which could eventually mitigate the noise. First, the optimum size of the units to obtain the highest noise reduction was investigated using 1/10 scaled model experiment, and sound attenuation experiments were carried out using a 1/2 mock-up model which is 2 m high and 5 m long. Total 1,137 unit blocks were made of synthetic woods with the size of $10{\times}10{\times}9cm$. These unit blocks were installed on the both side of the 1/2 mock-up steel framed noise barrier. As a result, it was revealed that the block typed vegetation noise barrier has 7 dB higher insertion loss in comparison with the general plane noise barrier. Also, it was found that the appropriate size of unit blocks is $20{\times}20cm$ which has large effect of sound insertion loss.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.7 s.112
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• pp.683-689
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• 2006

The sound absorption materials have been used to enhance the performance of a noise barrier and improve the room acoustics. In this study, 6 products of sound absorption materials generally used in Korea were chosen, and their absorption performance was tested in various conditions, that is, it was measured while changing thickness, density and air-gap in their back, and measured with or without facing on their face.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.5 s.122
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• pp.373-378
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• 2007

Today, the use of the sound absorptive material is increasing to improve the room acoustics in the auditorium and music hall, etc. Usually, the sound absorption materials have been used to enhance the performance of a noise barrier and improve the room acoustics in construction site. Generally, the sound absorbtion coefficients are the most important factor reflecting the sound absorbtion performance. There are two methods to measure the sound absorption coefficient. The first one is the reverberation room method, and the second is the impedance tube method. In this study, we measure the sound absorbtion coefficients using these two methods, and then we compared the results of the sound absorbtion coefficients to look into the difference of results between reverberation room method and impedance tube method. Also we compared the results of the sound absorbtion coefficients with respect to the size of sample and the volume of reverberation room. From the experiment, we could see that the sound absorbtion coefficients are measured equally for different sample size. But the sound absorbtion coefficients are measured differently according to test methods and test conditions.