• Title, Summary, Keyword: Noise Reduction

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An Analysis on Noise Reduction Effects of Two-Layer Low Noise Pavements using Statistical Methods (통계적 방법을 이용한 복층 저소음포장의 소음저감효과 분석)

  • Lee, Sang Hyuk;Han, Dae Seok;Yoo, In Kyoon;Lee, Soo Hyung
    • International Journal of Highway Engineering
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    • v.19 no.6
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    • pp.1-11
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    • 2017
  • PURPOSES : The purpose of this study is to compare noise reduction quantities between before/after two-layer low noise pavement implementation using equivalent noise level analysis and to analyze the noise reduction effects of the two layer low noise pavement with a statistical method such as the Anderson-Darling Test. METHODS : In order to compare and to analyze noise reduction effects between before/after two-layer low noise pavement implementation, data acquisition as noise levels on a roadside and an apartment rooftop was conducted in the study area. The equivalent noise level was estimated in order to compare noise reduction quantities and the Anderson-Darling Test was carried out for estimating noise reduction effects of the two-layer low noise pavement. RESULTS : The equivalent noise levels of before/after two-layer low noise pavement implementation for the roadside during the daytime are 65.355 dB and 63.520 dB and during the nighttime are 62.463 dB and 59.088 dB. The equivalent noise levels for the apartment rooftop during daytime are 57.301 dB and 59.088 dB and during the nighttime are 54.616 dB and 52.464 dB. Also two-layer low noise pavement decreased the noise reduction effects estimated with the statistical method as the Anderson-Darling test for the roadside during the daytime by around 66.68% and decreased noise reduction effects on the roadside during the nighttime by 0.70%. Moreover it reduced noise reduction effects in the apartment rooftop during the daytime and nighttime by 0% and 96.32%, respectively. CONCLUSIONS : Based on the result of this study, two-layer low noise pavement can positively affect noise reduction during both the daytime and nighttime according to the results of estimating the equivalent noise levels and the Anderson-Darling test.

Noise-reduction Function and its Affecting Factors of Plant Communities

  • Song, Xiu-hua;Wu, Qian-qian;Yu, Dong-ming;PIAO, Yong-ji;Cho, Tae-Dong
    • Journal of Environmental Science International
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    • v.25 no.10
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    • pp.1407-1415
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    • 2016
  • In this study, we investigated the relationship between noise reduction and the community structure of nine groups of typical plant communities as well as the reduction in noise at different frequencies. The semantic differential method was adopted to explore the perception of noise reduction. The results indicated that there was a significantly positive correlation between noise reduction and coverage, a significantly negative correlation between noise reduction and bifurcate height, and a negative correlation between noise reduction and bare rate. However, there was no significant correlation between noise reduction and height, diameter at breast height, or crown width. The reduction of middle-frequency noise was better than that of low- and high-frequency noise. The indicators "quiet" and "calm" showed that plant communities could reduce the noise perceived by humans. However, overly dense woodland caused nervousness, fear, depression, and other negative effects. Relatively open environments and those with large forest gaps obtained the highest evaluation.

Noise Reduction of PDP TV Cooling Fan System through Parameter Analysis (인자 분석을 통한 플라즈마 디스플레이 패널(Plasma Display Panel) 텔레비전에서의 냉각 홴 시스템 소음 저감)

  • Kim, Kyu-Young;Choi, Min-Goo;Lee, Duck-Joo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.16 no.2
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    • pp.107-114
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    • 2006
  • The present experimental study deals with noise reduction and improvements in cooling performance in a plasma display panel (PDP) television (TV). The main ideas of the fan system noise reduction are maintenance of uniform inflow condition and reduction of the system loss, ${\Delta}P.$ The discrete noise is mainly related with the inflow condition therefore removing the structure which distorts inflow makes the discrete noise reduction. The broadband noise in PDP TV is related with the system losses which result from the presence of the fan downstream obstacle, PDP rear case. Through the modification of the distance and preventing the leakage flow between the fan and rear case, we can obtain the system loss and broadband noise reduction. Additionally we can reduce fan rotating speed because of increased flow rate which obtains from the reduction of system loss (resistance). Finally, 4.2 dB(A) noise reduction and $10\%$ increase in flow rate are achieved. From these results, we show that the reduction of system loss is the most effective way of the fan system noise reduction.

Fast non-local means noise reduction algorithm with acceleration function for improvement of image quality in gamma camera system: A phantom study

  • Park, Chan Rok;Lee, Youngjin
    • Nuclear Engineering and Technology
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    • v.51 no.3
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    • pp.719-722
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    • 2019
  • Gamma-ray images generally suffer from a lot of noise because of low photon detection in the gamma camera system. The purpose of this study is to improve the image quality in gamma-ray images using a gamma camera system with a fast nonlocal means (FNLM) noise reduction algorithm with an acceleration function. The designed FNLM algorithm is based on local region considerations, including the Euclidean distance in the gamma-ray image and use of the encoded information. To evaluate the noise characteristics, the normalized noise power spectrum (NNPS), contrast-to-noise ratio (CNR), and coefficient of variation (COV) were used. According to the NNPS result, the lowest values can be obtained using the FNLM noise reduction algorithm. In addition, when the conventional methods and the FNLM noise reduction algorithm were compared, the average CNR and COV using the proposed algorithm were approximately 2.23 and 7.95 times better than those of the noisy image, respectively. In particular, the image-processing time of the FNLM noise reduction algorithm can achieve the fastest time compared with conventional noise reduction methods. The results of the image qualities related to noise characteristics demonstrated the superiority of the proposed FNLM noise reduction algorithm in a gamma camera system.

Performance Comparison of Noise Reduction Algorithms for Enhancing Voice Quality based on Telematics (텔레메틱스 기반의 통화음질향상을 위한 잡음제거 알고리즘의 성능비교)

  • Kim, Hyoung-Gook;Choi, Hong-Jae
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.11 no.1
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    • pp.86-91
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    • 2012
  • To provide high voice quality of real-time voice communication based on telematics exposed to various noise environments, the noise reduction algorithm with low computing load is required to effectively remove the noise. In this paper, we propose a noise reduction algorithm based on Mel-Filter and illustrate the proposed algorithm comparing with conventional noise reduction algorithms. As a experimental result that evaluates the performance of the noise reduction algorithms under the car and babble noise environments, the proposed noise reduction algorithm has the lower computing load with the similar PESQ score compared to the conventional noise reduction algorithms. It proves that the proposed noise reduction algorithm can efficiently remove the noise in mobile telematics.

A Study on the Active Noise Control System for Road Noise Reduction Implementation and Characterization of Directional and Non-directional Speaker (도로 소음 저감용 능동소음 제어시스템의 구현과 지향성 및 무지향성 스피커의 특성 고찰)

  • Moon, Hak-Ryong;Lim, You-Jin
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.62 no.4
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    • pp.192-197
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    • 2013
  • Road traffic noise barriers being used to reduce the noise, but the city surroundings inhibition, ecosystem disturbance, and it is difficult to maintain. Can enhance or complement the existing noise barrier performance, so that it is necessary to develop an electronic noise-reduction system In this paper, we proposed an electronic road noise reduction devices to reduce road noise for a DSP-based signal processing and analog signal input-output controller. In order to verify the control performance, we performed noise reduction experimentation of ANC by filtered-X LMS algorithm and traffic noise signal injection. The controller is equipped with noise reduction algorithms were tested on the characteristics of directional and omnidirectional speaker.

Prediction Method for Trailing-edge Serrated Wind Turbine Noise (풍력발전기 톱니형 뒷전 블레이드 소음 예측 기법)

  • Han, Dongyeon;Choi, Jihoon;Lee, Soogab
    • New & Renewable Energy
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    • v.16 no.2
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    • pp.1-13
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    • 2020
  • The reduction of noise from wind turbines has been studied using various methods. Some examples include controlling wind turbine blades, designing low-noise-emitting wind turbine blades, and using trailing-edge serrations. Among these methods, serration is considered an effective noise reduction method. Various studies have aimed to understand the effects of trailing-edge serration parameters. Most studies, however, have focused on fixed-wing concepts, and few have analyzed noise reduction or developed a prediction method for rotor-type blades. Herein, a noise prediction method, composed of two noise prediction methods for a wind turbine with trailing-edge serrations, is proposed. From the flow information obtained by an in-house program (WINFAS), the noise from non-serrated blades is calculated by turbulent ingestion noise and airfoil self-noise prediction methods. The degree of noise reduction caused by the trailing-edge serrations is predicted in the frequency domain by Lyu's method. The amount of noise reduction is subtracted from the predicted result of the non-serrated blade and the total reduction of the noise from the rotor blades is calculated.

A study on the performance test and acoustic design of interference type noise reduction device for railway noise (철도소음 저감을 위한 간섭형 방음장치 음향 설계 및 성능시험에 관한 연구)

  • Cho, Jun-Ho;Koh, Hyo-In
    • Journal of Environmental Impact Assessment
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    • v.20 no.6
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    • pp.787-795
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    • 2011
  • Noise barrier is generally used with welding of joint rail for railway noise reduction in our country. But the noise barrier for high speed railway has weak point in low frequencies about 315Hz band. In this study, For developing of Interference-type Noise Reduction Device(INRD), acoustic analysis were performed using commercial software. For verifying the improvement in the noise reduction, noise measurement before and after installing of INRD were performed in Anechoic Chamber. From these acoustic analysis and noise measurement, it was known that developed INRD has a good noise reduction performance and can be used efficiently with conventional noise barrier.

A New Noise Reduction Method Based on Linear Prediction

  • Kawamura, Arata;Fujii, Kensaku;Itho, Yoshio;Fukui, Yutaka
    • Proceedings of the IEEK Conference
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    • pp.260-263
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    • 2000
  • A technique that uses linear prediction to achieve noise reduction in a voice signal which has been mixed with an ambient noise (Signal to Noise (S-N) ratio = about 0dB) is proposed. This noise reduction method which is based on the linear prediction estimates the voice spectrum while ignoring the spectrum of the noise. The performance of the noise reduction method is first examined using the transversal linear predictor filter. However, with this method there is deterioration in the tone quality of the predicted voice due to the low level of the S-N ratio. An additional processing circuit is then proposed so as to adjust the noise reduction circuit with an aim of improving the problem of tone deterioration. Next, we consider a practical application where the effects of round on errors arising from fixed-point computation has to be minimized. This minimization is achieved by using the lattice predictor filter which in comparison to the transversal type, is Down to be less sensitive to the round-off error associated with finite word length operations. Finally, we consider a practical application where noise reduction is necessary. In this noise reduction method, both the voice spectrum and the actual noise spectrum are estimated. Noise reduction is achieved by using the linear predictor filter which includes the control of the predictor filter coefficient’s update.

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An Effective Noise Estimator for Use in Noise Reduction

  • Han, Hag-Yong;Kwon, Ho-Min;Lee, Sung-Mok;Lee, Gi-Dong;Kang, Bong-Soon
    • Journal of information and communication convergence engineering
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    • v.9 no.1
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    • pp.59-63
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    • 2011
  • Conventional noise reduction filtering schemes realize limited improvements of the peak signal-to-noise ratio (PSNR) in the low-level noisy images. The flatness degree and the edge information are effectively used to estimate the noise volume. We propose a noise estimator for reducing noise in the AWGN (additive white gaussian noise) corrupted images using three intermediate image maps (FGM(flatness gray map), FIM(flatness index map), NEM(noise estimate map)). The proposed noise estimator is fed into the conventional noise reduction filters as a pre-processor. The performance of noise reduction is tested in the various AWGN corrupted images.