• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.757-761
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• 2001

In order to study noise barriers of complex shapes and to assess their efficiency, precise prediction model is required. For instance, geometrical approaches cannot deal with complex diffraction effects. So that in this paper, the time domain numerical computation method(Computational Aeroacoustics method) is applied to estimate noise reduction by diffraction and finite impedance condition. The CAA method can be used to calculate exactly the pressure of complex barrier shape with different impedance condition, such as T-shape, cylindrical edge and multi-edge noise barriers.

• 한국소음진동공학회논문집
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• 제20권9호
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• pp.791-796
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• 2010

Installing noise barriers is the most common method for reducing the highway traffic noise to the road side residential area. After the report about edge potential concept of a noise barrier, various types of noise reducing devices(NRDs) called "noise reducers" have been suggested for getting more shielding effect on the top of highway noise barriers. But, it has been doubtful about effect of the NRDs in field because there was no appropriate and unified method to estimate the acoustic performance by using field measurement of the NRDs in Korea. In this study, the authors have considered to setup a practical method to test and estimate the acoustic performance of NRDs. For eliminating the noise reduction effect of the NRDs height itself, the source and measuring points are adjusted as highly as the NRDs height. For the frequency weighting in the estimation of the NRDs effect, the highway noise spectra were measured at asphalt and concrete road side and then averaged for a unit spectral parameter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.2007-2008
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• 2011

In this paper, we implemented active noise control systems for active barriers with attenuation of road noise. And then we constructed by multi-channel audio systems and DAQ part, high performance DSP H/W. Active noise control firmware program was implemented for multi-channel off-line/on-line estimation methods for secondary path transfer functions and FIR/IIR filter structure main noise control algorithms. To evaluate performance of implemented systems, active barriers test bed was implemented and several experiments was performed by various noise cases.

• 대한환경공학회지
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• 제34권12호
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• pp.835-839
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• 2012

도심의 교통량의 증가와 더불어 급증하는 교통소음의 피해를 최소화하기 위하여 도로변 지역에 방음벽의 설치가 이루어지고 있다. 이에 따라 여러 형태의 방음벽 설치되었고, 그 형태와 재질에 따라방음성능, 시야확보측면, 유지관리 등에서 장단점이 존재한다. 최근 꾸준하게 적용되고 있는 반사형 투명형 방음벽의 경우, 시야를 확보할 수 있고 외관이 우수하지만 반사음의 영향을 고려해야 하는 단점이 있다. 본 연구에서는 방음벽 전면 형상에 의한 반사음의 영향을 분석하여 반사형 방음벽을 최적화하여 반사음의 영향을 최소화 하고자 하였다. 방음벽 전면에 두께가 다른 블록을 설치하고 일반 반사형 방음벽의 소음 반사 효과와 비교한 결과, 일반 반사형 투명 방음벽에 비하여 0.9~1.5 dB(A)의 소음저감 효과가 있었다. 또한 반사음이 증가 또는 감소하는 공간적 영역이 블록의 두께에 따라 변화하는 것을 알 수 있었다. 이러한 현상은 방음벽 전면 형상에 따라 소음의 집중 및 확산분포가 다양하게 변화하는 것을 나타내며 방음벽을 최적화하는 기술의 가능성을 보여주는 결과라고 판단 하였다.

• Asian Journal of Atmospheric Environment
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• 제8권2호
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• pp.81-88
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• 2014

Noise-barriers on both sides of the roadway (hereafter referred to as double noise-barriers), are a common feature along roads in Korea, and these are expected to have important effects on the near-road air pollution dispersion of vehicle emissions. This study evaluated the double noise-barrier impact on near-road air pollution dispersion, using a FLUENT computational fluid dynamics (CFD) model. The realizable k-${\varepsilon}$ model in FLUENT CFD code was used to simulate vehicle air pollutant dispersion, in around 11 cases of double noise-barriers. The simulated concentration profiles and surface concentrations under no barrier cases were compared with the experimental results. The results of the simulated flows show the following three regimes in this study: isolated roughness (H/W=0.05), wake interface (H/W=0.1), and skimming flow (H/W>0.15). The results also show that the normalized average concentrations at surface (z=1 m) between the barriers increase with increasing double noise-barrier height; however, normalized average concentrations at the top position between the barriers decrease with increasing barrier height. It was found that the double noise-barrier decreases normalized average concentrations of leeward positions, ranging from 0.8 (H/W=0.1, wake interface) to 0.1 (H/W=0.5, skimming flow) times lower than that of the no barrier case, at 10 x/h downwind position; and ranging from 1.0 (H/W=0.1) to 0.4 (H/W=0.5) times lower than that of the no barrier case, at 60 x/h downwind position.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.960-963
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• 2007

In this paper, development of the noise barrier analysis program is described. The upper part of barriers may have complicated shapes like "Y", "T", inverted L, and other shapes. The insertion loss of the barrier is predicted by summation of multiple diffractions occurring at top edge points. In addition, the program considers diffractions occurring at both vertical sides, while reflections from ground due to mirror images are also included. In case of two barriers at both sides of the road, reflections from the other side of barriers are considered, in which magnitudes are decreased by the ratio of absorption coefficient.

• Environmental Engineering Research
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• 제20권4호
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• pp.383-391
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• 2015

Transparent type noise barrier is a desirable facility since it provides a secure view to drivers and passengers. However, reflection from this type of barrier could annoy dwellers on the sides of the road. To reduce reflection noise by transparent type barrier, modification can be made to the shapes on the front side and hence get effects by distortion of sound transmission. To achieve this, we have conducted simulation by which the effects of patterned screens of noise barrier on high-ways were investigated. The reduction effects of reflected sounds were evaluated for swelling, swelling with curved, rectangular and V-shaped screen type barriers, compared to the planar panel. The emitting noise was generated by 6-lane road and the patterned noise barriers had shown the reduction effects, especially in swelling and swelling with curved type for middle height dwellers, and the V-shaped screen type for higher elevation dweller. The swelling-type showed a decrease of 0.7~1.2 dB, performing the best diminution effect among the tested noise barriers.

• 한국철도학회논문집
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• 제19권5호
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• pp.629-637
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• 2016

본 논문에서는 선로와 근접하여 설치하는 근접 방음벽에 관한 음향성능평가와 근접 방음벽의 삽입손실 예측을 위해 경계요소법 대신에 비교적 용이하게 사용 가능한 근사식의 제안에 관한 연구를 수행하였다. 우선, 근접 방음벽을 축척 모형으로 제작하여 무향실에서 음향성능평가를 수행하였으며, 스피커 음원 위치에 따른 총합 삽입손실을 등고선 형태로 분석하였다. 그리고, 무향실에서 수행한 축척 모형 근접 방음벽에 대한 삽입손실 측정결과를 이용하여 다양한 형상의 근접 방음벽에 대한 삽입손실 예측을 위한 근사식을 제안하였다. 또한, 무향실에서의 측정결과 및 예측결과와의 상호 비교를 통해 예측 프로그램의 타당성을 검증하였다. 마지막으로, 열차 소음원의 주파수 특성을 고려하고 높이가 1.0m, 상부 방음판의 크기가 0.5m이며 'ㄱ'자 형상을 갖는 흡음형 근접 방음벽을 철도의 건축한계선에 설치하는 경우에 대한 삽입손실 예측 및 음향성능 평가를 수행하였으며, 삽입손실 예측을 위한 근사식을 제안하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1493-1496
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• 2011

Research results for LMS-based algorithms performances using real records of the traffic noise are discussed. The various algorithms based on LMS method are studied regarding their convergence speed and noise reduction index. Most effective algorithms are chosen for implementation in the active noise control barriers. The optimal step size, and number of adaptive filter taps are addressed during parametric study of the algorithms.

• 한국안전학회지
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• 제20권2호
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• pp.6-10
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• 2005

With the rapid industrial development, railways have become a main traffic means of transportation. However, rail traffic noise and vibration have become a major problem in urban areas which is a very serious issue for the living environment. Especially, railway noise induced by rail operations has influenced on the residents living near railway tracks. The purpose of this paper is to investigate the Raynoise modeling in railway applications. Generally, my acoustics have been used to investigate the effectiveness of noise barriers in railway applications and barriers are modeled using the commercial software Raynoise. A-weighted sound pressure level have been measured at six locations, 4m from the track and are compared with experimental values. Based on the analysis of the results, Comparison between numerical and experimental values are within 1dB (A). Also, when a train is m through the Raynoise modeling, the general influential sphere of railway noise can be determined. Therefore, this study will be using basic data in establishing effective railway noise prevention plans far the future. Also, we could know that is applicable of Raynoise modeling at railway noise.