서지주요정보
다수의 마이크로폰을 이용한 실내 벽면의 어드미턴스 및 소음원 재구성 = Reconstruction of surface admittance and interior noise sources by using multiple microphones
서명 / 저자 다수의 마이크로폰을 이용한 실내 벽면의 어드미턴스 및 소음원 재구성 = Reconstruction of surface admittance and interior noise sources by using multiple microphones / 김영기.
저자명 김영기 ; Kim, Young-Key
발행사항 [대전 : 한국과학기술원, 1999].
Online Access 원문보기 원문인쇄

소장정보

등록번호

8010323

소장위치/청구기호

학술문화관(문화관) 보존서고

DME 99046

휴대폰 전송

도서상태

이용가능

대출가능

반납예정일

초록정보

The location and strength of primary noise sources is essential information in controlling interior noise of a vehicle or fuselage. In contrast to passive reactions, such as reflections and absorption, primary noise sources actively radiate sound into enclosures. Therefore, if we eliminate primary noise sources, we can obtain perfect control. The main objective of this research was to identify these primary sources, which can be defined as active sources. In the past decade, nearfield acoustic holography (NAH) has been used to identify exterior noise sources. Since NAH reconstructs a whole sound field on the basis of the sound pressure measured at a surface, it shows the distribution of noise sources. Moreover, numerical methods have been applied to reconstruct the sound field caused by arbitrarily shaped sources. However, regarding interior noise sources, whether NAH also shows active source distributions has not been verified. In contrast to exterior sound field, reflections are added to interior sound fields; therefore, the sound fields reconstructed by NAH may misrepresent the source distribution. This study addressed a holographic method that identifies active sound sources in interior sound fields. In the method, active sources are simply identified by eliminating passive reactions from the sound fields reconstructed by NAH. The first step of the method is to estimate surface characteristics, such as surface admittance or impedance. Since these characteristics control passive reactions, they are essential in identifying passive reactions. The second step is to apply acoustic holography to reconstruct the total sound field. The final step is to eliminate the passive reactions from the reconstructed total sound field. The a priori knowledge on surface characteristics is used in the final step. A technique that estimates surface admittance was also developed in this research. Since a large number of specimens are needed to measure the surface admittance of an entire surface, a technique that estimates in-situ admittance is required for the proposed method. Moreover, taking a specimen from its original surface needs careful attention and skills. The technique introduced in this paper measures the in-situ surface admittance of the area covered by a microphone array. This technique employs BEM-based nearfield acoustic holography to reconstruct surface velocity and pressure. The ratio of the surface velocity to the surface pressure gives the surface admittance. Errors in the proposed method were reduced by using a regularization process, and remaining errors were predicted. Usually, BEM-based nearfield acoustic holography is incorporated with a regularization process. Higher order mode components are filtered out since they produce enormous errors in predicted acoustic quantities. In this study, an optimal regularization process [B.-K. Kim and J. G.-Ih, J.Acoust.Soc.Am., 100, 3003-3016, 1996] was employed in order to reduce the errors. In addition, we predicted the errors that remain after regularization. The characteristics of the optimal regularization process and the statistics of measured noise were used to predict the errors. Numerical simulations and experiments were performed to verify the proposed method. Our technique which estimates surface admittance was applied to interior sound fields as well as exterior sound fields. The results proved that this technique can be used as an independent measurement tool. The active sources on surfaces were reconstructed, and they showed correct source locations.

서지기타정보

서지기타정보
청구기호 {DME 99046
형태사항 xiii, 129 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Young-Key Kim
지도교수의 한글표기 : 김양한
지도교수의 영문표기 : Yang-Hann Kim
수록잡지명 : "Holographic reconstruction of active sources and surface admittance inan enclosure". Journal of Acoustical Society of America, vol. 105, no. 4, pp. 2377-2383 (1999)
학위논문 학위논문(박사) - 한국과학기술원 : 기계공학과,
서지주기 참고문헌 : p. 125-129
주제 홀로그라피
경계요소법
임피던스
소음
소음원
Holography
BEM
Impedance
Noise
Source
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