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TRACKING FOR HIGH-ORDER DAMPING OF THIN BEAM OSCILLATION
Wan-Suk Yoo,Jae-Wook Lee,Hyun-Woo Kim 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
An estimation of high-order damping in flexible multibody dynamic simulation is introduced in this paper. The suggested damping model based on the experimental modal analysis leads to more accurate correlation results comparing to the traditional linear damping model because it directly uses the modal parameters of each mode achieved from experiment even high frequency modes. The modal parameters until the 5th mode are extracted from the experimental modal testing of the flexible beam using a high speed camera. And using the measured damping ratio and natural frequency until the 5th mode, the generic damping model is constructed. Then, the ANCF (absolute Nodal Coordinate Formulation) simulation results are compared to experimental results until the 5th mode.
Yoo Wan-Suk,Son Kwon,Lee Jang Myung,Lee Min Cheol,Han Sung Hyun,Park Un Sik,Choi Jae Weon,Lee Man Hyung 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.1
In this paper, a method for optimal placement of sensors and actuators is presented by using new measures of modal controllability and observability defined in a balanced coordinate system. The proposed new measures are shown to have a great advantage in practical use when they are used as criteria for selecting the locations of sensors and actuators, since the most controllable and observable locations can be obtained to be identical. In addition, they are more accurate than the measures of Hamdan and Nayfeh in that the effects of the eigenvector norm are considered into the magnitude of measures. I n simulations, to verify the effectiveness of the proposed measures and optimal placement method, the closed-loop response of a simply supported flexible beam, in which the number and locations of actuators are determined by using the proposed measures and optimal placement method, has been examined and compared with the case of Hamdan and Nayfeh's measures.
Dynamic analysis and design of a high voltage circuit breaker with spring operating mechanism
Wan-Suk Yoo,Seung-Oh Kim,Jeong-Hyun Sohn 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.12
Spring Operating Mechanism (SOM) is a dynamic system to open and close the circuit breaker in a voltage control-ling system. For a high-speed action of opening and closing within a few mili-seconds, a SOM consists of many links, joints, chains, and cams. Thus, various dynamic characteristics are occurred, especially large contact forces between the cam and the roller, the shaft and the stopper. To save time and money for a new design of SOM system, analysis of the mechanism is necessary. In this paper, a multibody dynamic analysis and test technique was applied for a SOM to pre-dict, estimate and validate forces occurring during the operation. For the multibody dynamic analysis, the ADAMS program was employed for 145kV circuit breaker with a SOM. For an accurate modeling, several components were sequentially added and the reliability of modeling was validated through the comparison with test data of opening and closing.
Physical Experiments for Large Deformation Problems
Wan-Suk Yoo,Jeong-Han Lee,Jeong-Hyun Sohn,Su-Jin Park 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
Many papers have studied computer simulations of elastic bodies undergoing large deflections and large deformations.<br/> But there have not been many attempts to check the validity of the numerical formulations because the simulation<br/> results could not be matched without correct input data such as material properties and damping effects. In this paper,<br/> these values are obtained from real experiment with a high-speed camera and a data acquisition system. The simulation<br/> results with the absolute nodal coordinate formulation (ANCF) are compared with the results of real experiments. Two<br/> examples, a thin cantilever beam and a thin plate, are studied to verify whether the simulation results are well matched<br/> to experimental results.
Relationship between subjective and objective evaluations of steering wheel vibration
Yoo, Wan-Suk,Na, Sang-Do,Kim, Min-Seok 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.5
Two passenger cars were driven at several speeds over several road profiles to evaluate the subjective ratings of steering wheel vibration. A 3-axis translational accelerometer was mounted on the steering wheel to measure the acceleration signal transmitted to the hands. Correlations were determined between the measured accelerations and the subjective ratings of 4 expert drivers and 10 general drivers by using Stevens' power law. The subjective ratings were found to be more highly correlated with the r.m.q. (root mean quad) values of the frequency-weighted acceleration than the r.m.q. (root mean square) values of the frequency-weighted acceleration. Also, the maximum values of r.m.q. (i.e., the component values in the dominant axis) had the highest correlation with the subjective ratings.