• Title/Summary/Keyword: Noise control

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A Study on the Plan for Advanced Noise-Policy in the 21st Century (21세기 소음정책 선진화 방안 고찰)

  • Yang, Geun-Ho;Park, Young-Min;Lee, Nae-Hyun;Chang, Yoon-Young
    • Journal of Environmental Impact Assessment
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    • v.18 no.1
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    • pp.21-30
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    • 2009
  • The study show that things about the noise control are indicated at The Noise & Vibration Control Act and the other Act. Also, the details program and total government ministries' program for the noise control are indicated what are the advance noise control plan. The study consist of the four part which are "Draw up the environmental noise infrastructure plan; the install shall be done the noisemap & the automatic noise measurement devices", "Resetting of environmental noise standard at the application area and Introduce of indoor noise; the guide for region classification of the noise standard & indoor noise", "Setting of aircraft noise standard and Program of measurement point operation; the noise-assessment-standard shall change from WECPN to new index($L_{den}$, $L_{dn}$, $L_{Aeq\;24h}$) & the operation and control of aircraft noise measurement changes from local environmental office to central control center" and "The method of noise regulation at construction site and the plan on making of standard for vibration regulation; It shall be made that the guideline of construction noise should include a target-construction, noise standard etc & the ministries shall unify control about construction vibration of the blasting vibration". The advance noise-policy will improve efficiency to deal with civil appeal & damage on residents about noise.

Active Noise Control in a Duct System Using the Hybrid Control Algorithm (하이브리드 제어 알고리즘을 이용한 덕트내 능동소음제어)

  • Lee, You-Yub;Park, Sang-Gil;Oh, Jae-Eung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.3
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    • pp.288-293
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    • 2009
  • This study presents the active noise control of duct noise. The duct was excited by a steady-state harmonic and white noise force and the control was performed by one control speaker attached to surface of the duct. An adaptive controller based on filtered x LMS(FXLMS) algorithm was used and controller was defined by minimizing the square of the response of the error microphone. The assemble controller, which is called a hybrid ANC(active noise control) system, was combined with feedforward and feedback controller. The feedforward ANC attenuates primary noise that is correlated with the reference signal, while the feedback ANC cancels the narrowband components of the primary noise that are not observed by the reference sensor. Furthermore, in many ANC applications, the periodic components of noise are the most intense and the feedback ANC system has the effect of reducing the spectral peaks of the primary noise, thus easing the burden of the feedforward ANC filter.

The Performance Improvement for an Active Noise Contort of Automotive Intake System under Rapidly Accelerated Condition (급가속시 자동차 흡기계의 능동소음제어 성능향상)

  • 이충휘;오재응;이유엽;이정윤
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.6
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    • pp.183-189
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    • 2003
  • The study of the automotive noise reduction has been concentrated on the reduction of the automotive engine noise because the engine noise is the major cause of automotive noise. However, many studies of automotive engine noise led to the interest of the noise reduction of the exhaust and intake system. Recently, the active control method is used to reduce the noise of an automotive exhaust and intake system. It is mostly used the LMS(Least-Mean-Square) algorithm as an algorithm of active control because the LMS algorithm can easily obtain the complex transfer function in real-time. Especially, Filtered-X LMS (FXLMS) algorithm is applied to an Active Noise Control system. However, the convergence performance of LMS algorithm went bad when the FXLMS algorithm was applied to an active control of the induction noise under rapidly accelerated driving conditions. So, in order to solve this problem, the modified FXLMS algorithm is proposed. In this study, the improvement of the control performance using the modified FXLMS algorithm under rapidly and suddenly accelerated driving conditions was identified. Also, the performance of an active control using the LMS algorithm under rapidly accelerated driving conditions was evaluated through the theoretical derivation using a chirp signal to have similar characteristics with the induction noise signal.

Active Window to Reduce the Exterior Noise Flowed Through the Open Window (열린 창문을 통해 유입되는 소음을 저감하는 능동소음제어 창문)

  • Kwon, Byoung-Ho;Park, Young-Jin
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.9
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    • pp.820-827
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    • 2011
  • Recently, noise has been regarded as one of the most notorious and frequent environmental pollutions which can be often encountered not only in the living space but also in the industrial site. Studies on physiological and psychological effects of long-term noise exposure to human being have commanded the public interest on noise issues. Since environmental noises such as traffic noise and construction noise is mainly flowed through the open window, it is necessary to develop the active noise control system to reduce it inside the building. Although control speakers and microphones for the noise signal measurement in the control region are essential for the conventional active noise control methods, it is impossible to implement them in the control region in the building environment because the control region is the living quarter and they may hinder activities of the residents. Therefore, we proposed the active window system to reduce the exterior noise flowed through the open window with microphones installed outside the window and control speakers installed at the frame of the window. To confirm the performance of the proposed active window, we carried out the simulation and experiment using active window system with 8 control speakers. Simulation results showed the noticeable noise reduction effect inside the control region within the frequency range without the spatial aliasing. Experimental result showed that the total acoustic potential energy inside the room of the scale model is reduced to about 10dB within the interest of frequency range.

Development of Active Noise Control System using DSP (DSP를 이용한 능동소음 제어시스템의 개발)

  • Kim, H.S.;Shin, J.;Oh, J.E.
    • Journal of the Korean Society for Precision Engineering
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    • v.11 no.1
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    • pp.108-113
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    • 1994
  • Active noise control technique has superior performance in low frequency ranges(50 .approx. 400Hz) to the conventional passive noise control technique. For the feasibility of active noise control, it is required to develop a controller which can implement control algorithm on real-time. In this study, therefore, real-time controller is developed using TMS320c25, high speed digital processor. Unlike conventional DSP board of complete ADD ON type, it is possible for the developed controller to interface with the other computer system easily by series communication for the convenience of program development. Furthermore it is designes to be separated readily as a control device. Active noise control of duct system is implemented ti evaluate a performance of developed device. Active noise control of duct system is implemented to evaluate a performance of developed controller using filtered-x LMS algorithm.

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Active Control of Propagated Noise through Opening of Enclosures Surrounding a Noise Source (음원을 둘러싼 인클로저 개구부를 통해 전파되는 소음의 능동 제어)

  • Lee, Hanwool;Hong, Chinsuk;Jeong, Weuibong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.4
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    • pp.223-231
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    • 2015
  • Enclosures are widely used to alleviate the contribution of machinery noise. It has been long concerned with the noise transmission through the access openings of the enclosures. In this study, we investigate active noise control technology for reduction of the transmission. A numerical model based on the acoustic boundary element method is first established. Using the numerical model, the acoustic transfer functions of the field points over the opening to the primary source at arbitrary locations are estimated. The feedforward control to minimize the acoustic power through the opening is then numerically implemented. The controller drives the secondary source to destructively interfere the noise transmission through the opening. Finally, a parametric study is conducted to evaluate the effects of the location and the number of the microphones on the control performance. Furthermore, the effects of the location of the secondary source on the performance of active noise control are investigated. It is followed that the control system implemented in this study leads to a significant reduction of about 31.5 dB in the sound power through the opening using only one secondary source located at the optimized position.

Development of Moving Bandpass Filter for Improving Control Performance of Active Intake Noise Control under Rapid Acceleration (급가속 흡기계의 능동소음제어 성능향상을 위한 Moving Bandpass filter 개발)

  • Jeon, Ki-Won;Oh, Jae-Eung;Lee, Choong-Hui;Lee, Jung-Yoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.1016-1019
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    • 2004
  • The study of the noise reduction of an automobile has been concentrated on the reduction of the automotive engine noise because the engine noise is the major cause of automotive noise. However, many studies of automotive engine noise led to the interest of the noise reduction of the exhaust and intake system. The method of the reduction of the induction noise can be classified by the method of passive control and the method of active control. However, the passive control method has a demerit to reduce the effect of noise reduction at low frequency (below 500Hz) range and to be limited by a space of the engine room. Whereas, the active control method can overcome the demerit of passive control method. The algorithm of active control is mostly used the LMS (Least-Mean-Square) algorithm because the LMS algorithm can easily obtain the complex transfer function in real-time. Especially, Filtered-X LMS (FXLMS) algorithm is applied to an ANC system. However, the convergence performance of LMS algorithm goes bad when the FXLMS algorithm is applied to an active control of the induction noise under rapidly accelerated driving conditions. So, in order to this problem, the modified FXLMS algorithm using Moving Bandpass Filter was proposed. In this study, MBPF was implemented and use ANC for automotive intake under revived rapidly accelerated driving conditions and it was verified its performance.

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A Multi-Channel Active Noise Control System for Controlling Humming Noise Generated by a Transformer (변압기 소음제어를 위한 다중채널 능동소음제어 시스템)

  • 이혁재;박영철;윤대희;차일환
    • Journal of KSNVE
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    • v.9 no.6
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    • pp.1137-1144
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    • 1999
  • Most of ANC(active noise control) researches are focused on adaptive algorithms, computer simulations and implementations of single-channel system in experimental environments. In this paper, a multi-channel ANC system based on DSP's was developed to obtain global attenuations over wide region and applied to the active control of the humming noise generated by a transformer. The developed ANC system including 24 microphones and 12 spearkers was applied to the real transformer noise reduction problem. Results showed that the control system could successfully control the humming noise over the region of interest.

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FEASIBILITY STUDY OF SOUND POWER BASED ACTIVE NOISE CONTROL STRATEGIES FOR GLOBAL NOISE REDUCTION

  • Kang, Seong-Woo;Kim, Yang-Hann
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1994.06a
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    • pp.785-790
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    • 1994
  • The active noise control which regards the acoustic power as a target function to be minimized, is analyzed to test its feasibility of which simplifies the measurement system compared with the global acoustic energy based active noise control system. In fact, it is found that the acoustic power based active noise control strategy is equally likely as good as the global acoustic energy based active noise control method if the acoustic field of interest is diffusive or very low model density one. In the intermediate model density field, we also demonstrate that the power based control gives the similar results as the energy based control in terms of global sound energy reduction for the lightly damped enclosure which might be most important system in practical application. From all the theoretical and power based control strategy is dependent on the characteristics of the acoustic field to be controlled; i.e., the model density distribution, the degree of reverberation, and on the strength of modal interaction of the control source with the primary source; i.e., the location of control source.

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A Study on the Performance of Optimization Techniques on the Selection of Control Source Positions in an Active Noise Barrier System (능동방음벽 시스템의 제어 음원 위치 선정에 미치는 최적화 기법 성능에 관한 고찰)

  • Im, Hyoung-Jin;Baek, Kwang-Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.1012-1015
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    • 2004
  • There have been several kinds of attempts to actively control the deflected noise behind the noise barrier. Omoto's work in 1993 would be one of the fundamental studies, where he placed the control sources uniformly parallel to the noise barrier. Following this study, Yang pointed that the average distance between the noise source and control sources is more important than the arrangement of control sources such as a straight line or an arc type distribution. In 2004, Baek tried to show optimal arrangement of control sources while keeping the average distance between the noise source and control sources. He used simulated annealing algorithm which is one of the natural algorithms for the selections of optimal control source positions, but the searching technique was a hybrid of the simulated annealing and the sequential searching to adapt to the vast amount of searching time. This study is about the performance comparison between the pure sequential searching and the hybrid one. The simulation results show very similar performance and a pure simulated annealing searching will be more beneficial for the noise reduction performance but at the cost of computing time.

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