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구조-음향 연성현상을 갖는 방사 방향을 가질 수 있는 방사체 설계방법
서희선(Seo, Hee-Seon),김양한(Kim, Yang-Hann) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.2
This paper presents a design method for the structural-acoustic coupled radiator that can emit sound in the desired direction. A coupled system that has a finite space and a semi-infinite space separated by two flexible walls and an opening is considered. An objective function is selected to maximize radiation power on a main axis and minimize a side lobe level. To get initial values, prediction of a pressure distribution on field points and radiation pattern of the structural-acoustic coupling system is shown at a coupled-resonant frequency. Three different optimization methods are adapted to design the coupled radiator. Pressure and intensity distribution of the designed radiator is presented.
서희선(Seo, Hee-Seon),조요한(Cho, Yo-Han),조치영(Joh, Chee-Young) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.9
A study was carried out to investigate the fluid-structure interaction phenomena of buried hydrophone system that exposed complex loads due to handling, transportation and installation. The buried hydrophone system has necessarily neighborhood structures for installation. Because of the neighborhood structure, acoustic field is deformed. We analyze the piezoelectric-structural-acoustic coupled problem and the results to use a finite element analysis software, ANSYS, which has an coupled field analysis capability. The effect of the component of hydrophone system is revealed altogether in pressure distribution. So, we classify and analyze the problem by four different compositions for decomposition.
입구와 유연한 구조물로 구성된 경계를 가지는 구조-음향 연성계의 수학적 표현
서희선(Seo, Hee-Seon),김양한(Kim, Yang-Hann) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.5
This paper explains a general coupling system in terms of the system parameters. impedance of a cavity or mobility of a structure. To easily access the mechanism of the structural-acoustic coupled system, a simple expression is derived. A general coupled equation is also derived of a general coupled problem constituted a flexible structure and an opening boundary in terms of vector and matrix notation, and is analyzed the coupling phenomena using the understanding acquired simple coupled system. The paper shows that the general coupled equation is expanded version of the simple coupled equation by some limiting checks. The paper also shows that the degree of coupling is proportioned to a stiffness of the acoustic system and a modal coupling coefficient, but is in inverse proportion to a mass of the structural system and the difference of the excitation frequency and resonant frequency of the acoustic or structural system.
방사 임피던스를 고려한 평면 배열 수중 음향 트랜스듀서의 최적 빔 설계
조치영,서희선,이정민,Joh, Chee-Young,Seo, Hee-Seon,Lee, Jeong-Min 한국음향학회 1996 韓國音響學會誌 Vol.15 No.1
이 논문에서는 최적의 빔패턴을 얻기 위한 비선형 최적 설계 기법을 제시하였다. 제시된 방법을 사용하여 진동체 사이의 자기 및 상호 방사 임피던스를 고려하여 최대 허용 부엽준위가 주어진 경우 빔폭이 최소화된 빔 패턴을 설계할 수 있다. 그리고 37개의 진동체가 X, Y 및 $45^{circ}$축에 대칭으로 배열된 평면 배열에 대해 제안된 기법을 적용한 결과 빔폭은 변화없이 상당히 낮은 부엽 준위를 얻었다. In this paper, a nonlinear optimal design technique is presented to find an optimal beam pattern. With this technique, the beam width is minimized with respect to a given maximum allowable side-lobe level considering the self- and mutual radiation impedances of vibrators. The proposed method is applied to design a planar array consisting 37 vibrators which are symmetric in X, Y and $45^{circ}$ axes. The results show that significantly low side-lobe level maintaining a main beam width can be obtained using this method.