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질량감도 해석에 의한 2차원 연속계의 진동특성에 관한 연구
이정윤,박호,오재응,Lee, Jung-Yoon,Park, Ho,Oh, Jae-Eung 대한기계학회 1990 대한기계학회논문집 Vol.14 No.2
Techniques which are able to predict and control dynamic characteristics, not affecting the vibrational characteristics on the modification of structural design, are being studied. As one of these techniques, experimental modal analysis is widely applied by many researchers. In this study, modal analysis is performed using transfer matrix method by a macro computer. The developed program would estimate the structural modal parameters precisely, and the validity of this program is certified by comparing with the experimental results of .GAMMA A. structure. Estimated modal parameters(natural frequency, vibrational mode, equivalent mass, etc.) are in accord with the experimental results. Also, the optimal location of the additive mass is determined by the evaluation of the vibrational mode and the equivalent mass. The relation between the additive mass and the equivalent mass is specified, and we come to know that the ratio of equivalent mass to additive mass alter linearly within the range of 20%.
인가전류 세기와 CIP 성분비에 따른 MRE의 전단계수 측정(Ⅱ)
오재응(Jae-Eung Oh),윤지현(Ji-Hyun Yoon),정재은(Jae-Eun Jung),파와지(Noor Fawazi),이정윤(Jung-Youn Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
MRE(Magneto-rheological Elastomer) is a material which shows reversible and various modulus in magnetic field. Comparing to conventional rubber vibration isolator, MREs are able to absorb broader frequency range of vibration. These characteristic phenomena result from the orientation of magnetic particle (i.e., chain-like formation) in rubber matrix. In this study, NR was used as a matrix in order to manufacture MREs. Magnetic reactive powder(MRP), having rapid magnetic reaction, was selected as a magnetic particle to give magnetic field reactive modulus. The mechanical properties of manufactured MREs were measured without the application of magnetic field. The results showed that the tensile property and resilience were decreased while the hardness was increased with the addition of CIP. The analysis of MR effect was carried out by FFT analyzer with various magnetic flux. As the addition of MRP and magnetic flux increased, increment of MR effect was observed.
이정윤(Jung Youn Lee),오재응(Jae-Eung Oh) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
This study proposed the analysis of mass position detection and modified stiffness due to the change of the mass and stiffness of structure by using the original and modified dynamic characteristics. The method is applied to examples of a cantilever and 3 degree of freedom by modifying the mass. The predicted detection of mass positions and magnitudes are in good agreement with these from the structural reanalysis using the modified mass.
감도계수 반복법을 이용한 비비례감쇠계의 고유치 및 고유벡터 변화량 해석
이정윤(Jung Youn Lee),오재응(Jae-Eung Oh),아민우딘아부(Aminudin Abu) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
This study predicts the modified eigenvectors and eigenvalues of the non-proportional damped structure due to the change in the mass, damping and stiffness of structure by iterative method of the sensitivity coefficient using the original dynamic characteristic. The method is applied to the non-proportional damped 3 degree of freedom system by modifying the mass, damping and stiffness. The predicted dynamic characteristics are showed a good agreement with these from the structural reanalysis using the modified mass, damping and stiffness.
오재응(Jae-Eung Oh),이정윤(Jung Youn Lee),이태훈(T. H. Lee),조용구(Joe Yong-Gu),김수현(Kim Soo-Hyun) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
In this study, it has been developed the program for predicting the noise spectrum of axial flow fan. The<br/> radiated acoustic pressure is expressed the discrete frequency noise peaks at BPF(Blade passage frequency)<br/> and its harmonics by Wu’s method and the line spectrum at the broad band by Wright’s method. And this<br/> paper presents the characteristics of a fan noise due to modify the design parameters. Accordingly, it is<br/> obtained the design parameter values for noise reduction of fan.
Co-FXLMS 알고리듬을 이용한 급가속시 자동차 흡기계의 능등소음제어
오재응(Jae-Eung Oh),이경태(Gyeong-Tae Lee),이해진(Hae-Jin Lee),방승우(Seung-Woo Bang),이정윤(Jung-Youn Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The method of the reduction of the automotive induction noise can be classified by the method of passive control and the method of active control. However, the passive control method has a demerit to reduce the effect of noise reduction at low frequency (below 500㎐) range and to be limited by a space of the engine room. Whereas, the active control method can overcome the demerit of passive control method. The algorithm of active control is mostly used the LMS (Least-Mean-Square) algorithm because the LMS algorithm can easily obtain the complex transfer function in real-time. Especially, When the Filtered-X LMS (FXLMS) algorithm is applied to an ANC system. However, the convergence performance of LMS algorithm goes bad when the FXLMS algorithm is applied to an active control of the induction noise under rapidly accelerated driving conditions. Thus Co-FXLMS algorithm was developed to improve the control performance under the rapid acceleration. The Co-FXLMS algorithm is realized by using an estimate of the cross correlation between the adaptation error and the filtered input signal to control the step size. In this paper, the performance of the Co-FXLMS is presented in comparison with that of the FXLMS algorithm. Experimental results show that active noise control using Co-FXLMS is effective to reduce automotive induction noise under the rapid acceleration.