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사종성(Jong Sung Sa),박석태(Seok-Tae Park) 한국소음진동공학회 2014 한국소음진동공학회 논문집 Vol.24 No.7
In this paper, horn loudspeaker modeling was suggested, investigated and verified through comparison of test results and simulation ones based on input electrical impedance curves and acoustic sensitivity ones. First, Thiele Small parameters of horn driver were identified by using pseudo loudspeaker model concept and verified in case of both closed and open horndriver. Second, cone-shaped horn models were investigated and compared with input acoustic impedance curves for real horn(cone angle 6.6˚) and short horn(cone angle 27.9˚). It showed that Leach model for cone horn was well described to test results, which were electrical impedance and acoustic sensitivity, compared to Lemaitre one. To represent horn system model good approximation in wide frequency range, mass correction filter and lowpass filter were adopted and consequently showed good fitted to test results.
신양현(Yang-Hyun Shin),김찬묵(Chan-Mook Kim),사종성(Jong-Sung Sa) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2
This paper presents the study of equivalent material properties with visco-elastic material properties.. The goal of the study is anticipation of equivalent material properties (natural frequency, loss factor, and Young's modulus) in damping materials treatment. Through the equivalent material properties, we must design FEM model with constrained layer damping material. And equivalent material properties saved solving time in FEM model. We could acquire the visco-elastic material properties (shear modulus, loss factor) to experiment the oberst test using modified ASTM. And we can anticipate resonance of constrained beam with shift ratio between bare beam and constrained beam. Equivalent material properties of constrained beam is obtained from shear parameters (g is made of shear modulus of visco-elastic material, length, and wave number) at resonance of constrained beam. FEM model of visco-elastic material must be designed solid model. We didn't design solid FEM model but equivalent shell FEM model. So we saved solving time and convenience of FEM model mesh.
자동차 루프의 진동제어를 위한 제진재의 위치 및 두께에 대한 실험적 연구
이정균(Jeong-Kyun Lee),김찬묵(Chan-Mook Kim),사종성(Jong-Sung Sa),홍성규(Sung-Kyu Hong) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper presents an experimental study on vibration characteristics of an automotive roof with damping material. The goal of the study is to extract modal parameters (natural frequency, loss factor, and mode shape) of automotive roof with damping materials treatment. To determine the effective positions and thickness of the damping material on a roof, vibration tests have been carried out for six cases; Aluminum plate with damping material on maximum strain energy, and aluminum plate with damping material on nodal line. From the result of aluminum plate, it is found that the damping material should be attached on the place with maximum strain energy part. For the automotive roof, patches of constrained damping material have been attached on the position of maximum strain energy and also implemented at the best position of applied damping treatment along each thickness of damping material. This paper addresses that the proper position of damping material is very important and the concept of maximum strain energy may be a good criterion for the placement of damping material.