Abstract ▼ AI-Helper

The present study is composed of two parts; an investigation of the insertion loss of the simple screen-type barrier located near a high rise building and development of new theoretical method for partially inclined barrier. In the first work, the noise barrier located near a high rise building is s...

The present study is composed of two parts; an investigation of the insertion loss of the simple screen-type barrier located near a high rise building and development of new theoretical method for partially inclined barrier. In the first work, the noise barrier located near a high rise building is studied experimentally as well as theoretically. The insertion loss is measured by using the direct method and compared to theoretical results obtained by applying Muradali and Fyfe's method (Applied Acoustics, Vol. 53, 49 ? 75, 1998). Although the barrier is partially inclined, it is modeled as a simple screen-type with the same height since the length of the inclined part is about 8 % of the total height. Multiple receiver images are used to represent the receiver point between the building and the barrier, because the receiver point is affected by the reflected waves from the building as well as the ground. The second work, which is the main part of this thesis, is to develop new prediction method for the partially inclined noise barrier where the length of the inclined portion is comparable to the total height. The prediction method is based on Kouyoumjian and Pathak's method (Proc. IEEE, Vol. 62, 1974) that deals with multiple diffraction. The scaled?down model test of the partially inclined barrier is done in anechoic room, where the effect of the finite length of the barrier is also studied. The comparison of theoretical and experimental values in narrow band spectrum shows that the theoretical result generally represents the average value of experimental insertion loss, while there are many oscillations in experimental result and some remarkable differences between two results are found in several frequency ranges. The theoretical method for 2D barrier is also studied, and the result is compared with the numerical result by using the 2D boundary element method. It is shown that the two results are in close agreement each other.

주제어