• Title/Summary/Keyword: Noise Problem

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Design of a New VSS-Adaptive Filter for a Potential Application of Active Noise Control to Intake System (흡기계 능동소음제어를 위한 적응형 필터 알고리즘의 개발)

  • Kim, Eui-Youl;Kim, Byung-Hyun;Kim, Ho-Wuk;Lee, Sang-Kwon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.2
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    • pp.146-155
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    • 2012
  • The filtered-x LMS(FX-LMS) algorithm has been applied to the active noise control(ANC) system in an acoustic duct. This algorithm is designed based on the FIR(finite impulse response) filter, but it has a slow convergence problem because of a large number of zero coefficients. In order to improve the convergence performance, the step size of the LMS algorithm was modified from fixed to variable. However, this algorithm is still not suitable for the ANC system of a short acoustic duct since the reference signal is affected by the backward acoustic wave propagated from a secondary source. Therefore, the recursive filtered-u LMS algorithm(FU-LMS) based on infinite impulse response(IIR) is developed by considering the backward acoustic propagation. This algorithm, unfortunately, generally has a stability problem. The stability problem was improved by using an error smoothing filter. In this paper, the recursive LMS algorithm with variable step size and smoothing error filter is designed. This recursive LMS algorithm, called FU-VSSLMS algorithm, uses an IIR filter. With fast convergence and good stability, this algorithm is suitable for the ANC system in a short acoustic duct such as the intake system of an automotive. This algorithm is applied to the ANC system of a short acoustic duct. The disturbance signals used as primary noise source are a sinusoidal signal embedded in white noise and the chirp signal of which the instantaneous frequency is variable. Test results demonstrate that the FU-VSSLMS algorithm has superior convergence performance to the FX-LMS algorithm and FX-LMS algorithm. It is successfully applied to the ANC system in a short duct.

The Verification on Effect of Sound Absorption Tunnel for Elevated Railway in Cholla Line (전라선 고가교 방음터널 효과검증)

  • Kim, Byoung-Sam;Lee, Tae-Keun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.667-672
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    • 2007
  • The source of wayside noise for the train are the aerodynamic noise, wheel/rail noise, and power unit noise. The major source of railway noise is the wheel/rail noise caused by the interaction between the wheels and rails. The Structure borne noise is mainly a low frequency problem. The train noise and vibration nearby the elevated railway make one specific issue. In this paper, the train noise and structure borne noise by train are measured. From the results, we investigated the effect on the sound absorption tunnel for elevated railway.

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A Study on the Noise Reduction in Railway Vehicles using Bone Conduction Device : Railway noise analysis and Understanding Acoustic Characteristics of Bone Conduction Devices

  • Park, Hyung Woo
    • International Journal of Internet, Broadcasting and Communication
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    • v.8 no.4
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    • pp.48-53
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    • 2016
  • Noise and vibration pollution is emerging to people in high speed trains. And it is difficult to realization of eco-friendly railway system at noise problem. The railway internal noise is 73dB on average and over 80dB in the loudest section. In order to reduce noise, there are passive methods that are far from noise sources and theother active noise reducion method. In this paper, we propose a method of reduce noise by measure and estimate the noise condition of train environment using Bone-Conduction device. We use an anti-phase waveform for canceling of noise characteristic. With this new system, the noise from surrounding environments can be reduced.

Improvement Noise Attenuation Performance of the Active Noise Control System Using RCMAC (RCMAC를 이용한 능동소음 제어시스템의 소음저감 성능개선)

  • Han, S.I.;Yeo, D.Y.;Kim, S.H.;Lee, K.S.
    • Journal of Power System Engineering
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    • v.14 no.5
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    • pp.56-62
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    • 2010
  • In this paper, a recurrent cerebellar modulation articulation control (RCMAC) has been developed for improvement of noise attenuation performance in active noise control system. For the narrow band noise, a filter-x least mean square (FXLMS) method has bee frequently employed as an algorithm for active noise control (ANC) and has a partial satisfactory noise attenuation performance. However, noise attenuation performance of an ANC system with FXLMS method is poor for broad band noise and nonlinear path since it has linear filtering structure. Thus, an ANC system using RCMAC is proposed to improve this problem. Some simulations in duct system using harmonic motor noise and KTX cabin noise as a noise source were executed. It is shown that satisfactory noise attenuation performance can be obtained.

Design Methodologies for Reliable Clock Networks

  • Joo, Deokjin;Kang, Minseok;Kim, Taewhan
    • Journal of Computing Science and Engineering
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    • v.6 no.4
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    • pp.257-266
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    • 2012
  • This paper overviews clock design problems related to the circuit reliability in deep submicron design technology. The topics include the clock polarity assignment problem for reducing peak power/ground noise, clock mesh network design problem for tolerating clock delay variation, electromagnetic interference aware clock optimization problem, adjustable delay buffer allocation and assignment problem to support multiple voltage mode designs, and the state encoding problem for reducing peak current in sequential elements. The last topic belongs to finite state machine (FSM) design and is not directly related to the clock design, but it can be viewed that reducing noise at the sequential elements driven by clock signal is contained in the spectrum of reliable circuit design from the clock source down to sequential elements.

A Study on a Method to Apply to Domestic Railway Vehicles in Prediction of Railway Noise Using a Noise Map (소음지도를 이용한 철도소음 예측 시 국내 철도차량 적용 방안 연구)

  • Park, Chan-Youn;Park, In-Sun;Oh, Jong-Hwa;Park, Sang-Kyu
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.882-888
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    • 2008
  • The increase in logistics and the emergence of high speed vehicles are aggravating the noise problem, and disturbing large numbers of people. Therefore, growing attention is being paid to the creation and utilization of a noise map in order to grasp and predict the influence of noise, and to establish a policy that effectively reduces noise. However, so far there has been little progress in developing a predictive formula for railway noise, and a noise prediction program suitable for the domestic environment. Therefore, there is a need for a method to apply the overseas prediction formula to domestic railway vehicles. This study evaluated the prediction method, the result of which is similar to that of a real measurement, using a noise map. It also employed a commercial software program, SoundPlan, to predict noise.

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The Verification on Effect of Sound Absorption Tunnel for Elevated Railway (고가철교 방음터널 효과검증)

  • Kim, Hyung-Doo
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.3
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    • pp.122-127
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    • 2008
  • The source of wayside noise for the train are the aerodynamic noise, wheel/rail noise, and power unit noise. The major source of railway noise is the wheel/rail noise caused by the interaction between the wheels and rails. The Structure borne noise is mainly a low frequency problem. The train noise and vibration nearby the elevated railway make one specific issue. The microphone array method is used to search sound radiation characteristics of elevated structure to predict the noise propagation from an elevated railway. In this paper, the train noise and structure borne noise by train are measured. From the results, we investigated the effect on the sound absorption tunnel for elevated railway.

A Study on Development and Application of Noise Estimation System for Floor Noise in Apartment Buildings (공동주택 층간소음의 소음 발생 위치 추정 시스템 개발 및 적용에 관한 연구)

  • Yun, Gee-Hyei;Kim, Sang-Yong
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.11a
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    • pp.203-204
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    • 2019
  • Recently, the number of conflicts and complaints related to noise between floors is increasing every year. It is essential to acquisition objective noise data in order to resolve legal disputes over floor noise. However, specialized equipment for noise acquisition is difficult for ordinary apartment dwellers to use. In addition, in order to solve the problem of inter-layer noise, it is most effective to locate and remove the noise. Therefore, this study proposes a floor noise monitoring system for the measurement of floor noise and estimation of the noise source that can be measured without a professional device.

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Comparison of Noise Suppression Methods in Voice CODEC (음성부호화기에서의 잡음제거 방식 비교)

  • 이진걸;기훈재
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.1203-1206
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    • 1998
  • Considerable research in the last three decades has examined the problem of enhancement of speech degraded by additive background noise. We compare traditional methods such as spectral subtraction and Wiener filter, recently proposed psychoacoustic model based methods such as perceptual filter and noise suppression in EVRC in terms of performance and complexity.

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