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정재순(Jaesoon Jung),구성열(Seongyeol Goo),왕세명(Semyung Wang) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
A metamaterials is an artificially engineered structure having stop bands (or band gaps) that are frequency bands in which waves cannot propagate. Taking advantage of the stop band the vibration isolation and wave focusing become possible. Using these phenomenon of metamaterial, this paper presents applications of the metamaterial for improvement of vibro-acoustic performances of mechanical systems. Based on the vibration isolation the possibility of structure-borne noise reduction is presented. Furthermore, based on the wave focusing phenomenon the improvement of radiation efficiency of flat panel speaker is presented.
왕세명(Semyung Wang),정재순(Jaesoon Jung),현재엽(Jaeyub Hyun) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.4
Noise insulation panels have been widely used to insulate the sound from the source to receiving region. Generally, the noise insulation performance of the panel is proportional to the product of mass and frequency of the noise source. This is known as mass law. Therefore the noise insulation panel is very weak to the low frequency noise. Although the noise insulation performance is proportional to the mass also, increasing mass should be avoided for many machines. To overcome this limitation, the acoustic metamaterial is proposed, recently. The acoustic metamaterial is a grid structure which composed of thick frame and thin plate. Using the anti-resonance effect, the acoustic metamaterial shows good noise insulation performance in low frequency region compared with flat panel with same mass. To design and investigate the noise insulation performance of acoustic metamaterial based panel, the effective analysis method should be established. Thus, this paper presents the finite element analysis procedure for acoustic metamaterial based noise insulation panel. The panel is discretized by 3node triangular element and the radiated sound is computed by assuming the panel as a set of elementary radiators. The computed transmission loss shows acoustic metamaterial is better compared with flat panel with the same mass.