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타일형 프로젝터를 이용한 저주파 능동 반향음 감소 기법
이재완,우상범,장하다,이근상,김완구,강휘석,엄원석,박영철,윤석왕,서영수,Lee, Jae-Wan,Woo, Sangbeom,Jang, Hada,Lee, Keunsang,Kim, Wan-Gu,Kang, Hwi-Suk,Ohm, Won-Suk,Park, Youngcheol,Yoon, Suk Wang,Seo, Youngsoo 한국음향학회 2014 韓國音響學會誌 Vol.33 No.6
저주파 능동 소나를 이용한 잠수함 탐지 기술이 개발됨에 따라, 기존의 수동 무반향 타일을 대치할 새로운 잠수함 스텔스 기술이 요구되는 추세이다. 본 연구에서는 선체 표면과 같은 대면적에 적용 가능한 타일형 프로젝터를 이용하여 능동 임피던스 정합을 구현함으로써 저주파 반향음 감소를 도모하는 기법을 제안한다. 먼저 능동 임피던스 정합 기법의 기술적 타당성을 확인하기 위하여 유한요소 모델을 이용한 저주파 반향음 감소 시뮬레이션을 수행하였다. 이를 바탕으로 타일형 프로젝터를 설계 및 제작하여 음향수조에서 저주파 반향음 감소 실험을 수행하였다. With the advent of submarine detection technology using low-frequency active sonar there is a call for a new submarine stealth device that can replace the existing passive anechoic tiles. Proposed in this study is a low-frequency echo reduction technique based on active impedance matching, which employs a tile projector designed to cover a wide area such as the surface of a ship. To judge the feasibility of the active impedance matching technique finite-element simulations of low-frequency echo reduction are performed. Based on the analysis, a tile projector is designed, fabricated, and tested in an acoustic tank for its low-frequency echo reduction performance.
Active control of low-frequency noise in bubbly water-filled pipes
노응휘,우상범,이동주,송민호,이재완,이훈기,엄원석,장하다,이근상,박영철,서영수 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7
This paper describes an active silencer system for low-frequency noise in water-filled pipes, with implementation in marine vessels and structures in mind. Active noise control in underwater environment has its unique challenges arising from bubbles. In this light the effect of bubbles on active noise control in water-filled pipes is explored, and a design guideline for a robust active silencer is proposed. The silencer consists of an underwater sound source, an error hydrophone, and an electronic controller programmed with an adaptive filter. The adaptive filter is updated using the filtered-x least mean square algorithm. Estimation of the incoming noise is performed using an adaptive notch filter. The performance of the active silencer is tested for pure tone noises below 500 Hz in a water-filled pipe connected to a reservoir. Notable reduction of noise is achieved with varying degrees of success at different bubble fractions.