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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.
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.
조치영,서희선,김대환,Joh, Chee-Young,Seo, Hee-Seon,Kim, Dae-Hwan 한국음향학회 1995 韓國音響學會誌 Vol.14 No.5
압전 세라믹의 재료 정수 규명의 일반적인 방댄은 어떤 형상과 분극 방향을 가진 진동체의 동특성을 이용하는 것이다. 본 논문에서는 압전 세라리의 복소 재료 정수극 규명하는 방법을 제시하였다. 이 방법은 이론적인 이미턴스 값과 실험으로 측정된 값과의 오차가 최소화 되도록 하는 비선형 최적화 기법을 사용하여 손실이 고려된 복소 압전 재료 정수를 규명하는 것이다. 재료 정수 규명을 위하여 이미턴스(Immittance)를 공진 주파수 근처와 저주파 영역을 포함하여 측정한 값을 동시에 활용하였다. 본 논문에서 제안된 방법을 검증하기 위해 PZT4 세라믹의 복소 재료 정수를 실험적으로 규명하였다. The common practice for the identification of piezoelectric properties is based on the use of immittance of a resonator with a certain geometry and poling direction. In this paper, a new method is suggested to identify the complex-valued piezoelectric material constants. This method Is based on the minimization of differences between the analytical immittance and the experimental measurement of resonator. Non-linear minimization problems are formulated to find out the unknown properties relevant to the resonators. The immittance data used for identification are measured at a number of frequencies which cover the vicinity of resonance frequency and the low frequency region. To illustrate the proposed technique, the complex-valued coefficients are identified for a typical PZT4 ceramic composition.