전원주 교수

We propose a metaliner that can insulate the duct noise for various grazing flow speeds with little flow resistance. The metaliner, whose unit cell consists of two different Helmholtz resonators with subwavelength scales, is placed underneath the duct. In order to predict sound insulation and absorption of metaliner in a duct with flow, an effective impedance model of the metaliner is established by considering the effect of flow. We present a design procedure for a metaliner with high transmiss

We propose a sound-absorbing nonplanar metasurface by considering locally different incidence angles along the metasurface. Perfect sound absorption is realized with the aid of hybrid resonance between two different subwavelength Helmhwoltz resonators comprising a unit cell. We theoretically investigate the effect of incidence angles on the sound absorption of the unit cells, and present a design method of the nonplanar metasurface that achieves perfect absorption by considering locally differen

Previous studies have explored the relationship between termite branch tunnel geometry and foraging efficiency in a model simulation in which foraging efficiency, γ, for two termite species, Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), was investigated in response to two variables, the probability of tunnel branching (P(branch)) and the probability of tunnel branch termination (Pterm). It was found that simulated tunnel patterns based on empiri

Diffraction by a flat airfoil in uniform flow is analytically examined, focusing on the acquisition of an accurate series solution for both low- and high-frequency incident waves. Formulation of integral equations is based on the use of the Wiener-Hopf technique in the complex domain. As the kernels of the integral equations are multivalued functions having a branch cut in the complex domain, the unknown in the integral operator is assumed to be a constant Therefore, the solution is a zeroth-ord

This study starts with a simple question: can we efficiently reduce the vibration of plates or beams using a lightweight structure that occupies a small space? As an efficient technique to damp vibration, we adopted the concept of an Acoustic Black Hole (ABH) with a simple modification of the geometry. The original shape of an ABH has a straight wedge-type profile with power-law thickness, with the reduction of vibration in beams or plates increasing as the length of the ABH increases. However,