• Title/Summary/Keyword: 밀폐음장

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fictive Noise Control of Enclosed Sound Field Using LQR Controller (LQR 제어기를 이용한 밀폐음장의 능동소음제어)

  • 유우열;김우영;황원걸;이유엽
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.1
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    • pp.12-20
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    • 2002
  • To control the noise of an enclosed sound field, we built a state space model using the acoustic modal parameter description. Using the state space model, we can investigate the controllability and observability, and find an appropriate position of control speaker and microphone to control sound field of the enclosed space. We implemented LQR(linear quadratic regulator) controller and reduced order observer to reduce the first acoustic mode. Experiments showed satisfactory results of 4∼10 dB reduction of magnitude of the first acoustic mode, and support the feasibility of the proposed scheme to lightly damped acoustic field.

Analysis of the Sound Field in an Enclosure on the Speaker System Using the Finite Element Method (유한요소법을 이용한 스피커 시스템 밀폐함 내부의 음장해석)

  • Lee, Woo-Seop;Kim, Jung-Rag;Chang, Ho-Gyeong;Kim, Ye-Hyun
    • The Journal of the Acoustical Society of Korea
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    • v.16 no.3
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    • pp.26-32
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    • 1997
  • In this study, the interior acoustic field of a speaker system with rectangular closed cavity and its effect on the impedance and the sound pressure reponses are investigated by applying the finite element method to the rectangular enclosure. Based on a good agreement with the theoretical and the experimental, it is founded that FEM is useful method for the development of a speaker system generating the diverse mode.

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The Active Noise Control in Harmonic Enclosed Sound Fields (I) Computer Simulation (조화가진된 밀폐계 음장에서의 능동소음제어 (I) 컴퓨터 시물레이션)

  • Oh, Jae-Eung;Lee, Tae-Yeon;Kim, Heung-Seob;Shin, Joon
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.5
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    • pp.1054-1065
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    • 1993
  • A computer simulation is performed on the effectiveness of the active minimization of harmonically excited enclosed sound fields for producing global reduction in the amplitude of the pressure fluctuations. In this study for the appreciable reductions in total time averaged acoustic potential energy, $E_{pp}$, the transducer location strategies for three dimensional active noise control is presented based on a state space modal which approximates the closed acoustic field.In this study, the above theoretical basis is used to investigate the application of active control to sound fields of low modal density. By the used of room-like 3-dimensional rectangular enclosure it is demonstrated that the reductions in $E_{pp}$ can be achieved by using a single secondary source, provided that the source is placed within the half a wavelength from the primary source and placed away from nodal line of the sound field. Concerning the reductions in $E_{pp}$ by minimzing the pressure in sound fields by the use of 3-dimensional rectangular enclosure, the effects of the number of sensors and the locations of these sensors are investigated. When a few modes dominate the response it is found that if only a limited number of sensors are located away from nodal line and located at the pressure maxima of the sound field such as at each corner of a rectangular enclosure.

Energy Density Control for the Global Attenuation of Broadband Noise Fields (광대역 잡음의 전역 감쇠를 위한 에너지 밀도 제어)

  • Park, Young-Cheol;Yun, Jeong-Hyeon;Youn, Dae-Hee;Cha, Il-Whan
    • The Journal of the Acoustical Society of Korea
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    • v.15 no.2
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    • pp.21-32
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    • 1996
  • The performance of the energy density control algorithm for controlling a broadband noise is evaluated in a one-dimensional enclosure. To avoid noncausality problem of a control filter, which often happens in a frequency domain optimization, analyses presented in this paper are undertaken in the time domain. This approach provides the form of the causally constrained optimal controller. Numerical results are presented to predict the performance of the active noise control system, and indicate that imp개ved global attenuation of the broadband noise can be achieved by minimizing the energy density, rather than the squared pressure. It is shown that minimizing the energy density at a single location yields global attenuation results that are comparable to minimizing the potential energy. Furthermore, unlike the squared pressure control, the energy density control does not demonstrate any dependence on the error sensor location for this one-dimensional field. A practical implementation of the energy-based control algorithm is presented. Results show that the energy density control can be implemented using the two sensor technique with a tolerable margin of performance degradation.

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