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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society for Noise and Vibration Engineering
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Journal DOI :
The Korean Society for Noise and Vibration Engineering
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Volume & Issues
Volume 12, Issue 12 - Dec 2002
Volume 12, Issue 11 - Nov 2002
Volume 12, Issue 10 - Oct 2002
Volume 12, Issue 9 - Sep 2002
Volume 12, Issue 8 - Aug 2002
Volume 12, Issue 7 - Jul 2002
Volume 12, Issue 6 - Jun 2002
Volume 12, Issue 5 - May 2002
Volume 12, Issue 4 - Apr 2002
Volume 12, Issue 3 - Mar 2002
Volume 12, Issue 2 - Feb 2002
Volume 12, Issue 1 - Jan 2002
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Active Optimal Control Techniques for Suppressing Dynamic Load in Vibration
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 10, 2002, Pages 749~757
DOI : 10.5050/KSNVN.2002.12.10.749
Excessive vibration in flexible structures is a problem encountered in many different fields, causing fatigue of structural components. Passive techniques, though sometimes limited in their capabilities, have been used in the past to attenuate vibrations. Recently active techniques have been developed to enhance vibration control performance beyond that provided by their passive counterparts. Most often, the focus of active control methods has been to suppress structure displacements. In cases where vibration results in structure failures, displacement suppression may not be the best choice of control approaches (it can, in fact, increase dynamic loads which would be even more harmful to supports) . This paper presents two optimal control methods for attenuating steady state vibrations in flexible structures. One method minimizes shaft displacements while another minimizes dynamic reaction forces. The two methods are applied to a model of a typical flexible structure system and their results are compared. It is found that displacement minimization can increase loads, while load minimization decreases loads.
Noise Prediction of Korea High Speed Train (KHST) and Specification of Sub-components
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 10, 2002, Pages 758~765
DOI : 10.5050/KSNVN.2002.12.10.758
KITECH and ODS performed a study of internal and external noise prediction of the Korean high speed prototype test train(HSR 350X). The object of this study was 3 kinds of cars, trailer car(TT2), motorized car(TMI ) and power car(TPI) and the predicted noise was for the two different driving speeds in free field and tunnel conditions. Data of carbody design and noise sources were delivered from manufactures. Some of noise sources which were not available in the project team, were chosen by experiences of ODS. Internal noise level of each car was predicted for two cases i.e, at 300 km/h and 350 km/h. In addition sound transmission path and dominant noise sources were also investigated for each section of the car, which is circular shell typed part of whole carbody. In case of TT2, the dominating sound transmission path is the (floor in terms of structure-borne noise and air-borne noise. The main noise sources are structure-borne noise from the yaw-damper and air-borne noise from the wheel/rail contact, whereas the dominating sound transmission path of TMI are floor and sidewall below the window in terms of structure-borne noise. The main noise sources of TMI are structure-borne noise from motor/gear unit and the yaw-damper in the free field, and air-borne noise from the wheel/rail contact and structure-borne noise from motor/gear unit in the tunnel. Through the external noise prediction for the KHST test train formation, the noise form the wheel/rail contact is estimated as one of the major sources. In addition, the noise specification of sub-component was proposed for managing each sub-surpplier to reach the KHST noise requirement. The specification provide the sound power of machinery part and transmission loss of component of carbody structure. The predicted noise level in each case exceeded the required limit. Through this study, the noise characteristics of the test train were investigated by simulation, and then the actual test will be performed in near future. Both measured and calculated data will be compared and further work for noise reduction will be continued.
An Assessment of Elastic and Damping Material Properties of PVC/MBS by an Acoustic Resonance Method
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 10, 2002, Pages 766~772
DOI : 10.5050/KSNVN.2002.12.10.766
In this investigation, experimental attempts were made to observe and determine the variations in elastic and damping properties of the PVC depending on the amounts of MBS added to the mixture, PVC/MBS, and also on the thicknesses of the specimens. An acoustic resonance technique was used for the tests In this investigation. It serves as a method to characterize properties of materials set in vibrational motions, which is initiated by low level stresses generated by externally supplied acoustic energy. Substantial variations were observed in the test results with the addition of the MBS to the PVC. It was found that the magnitudes of elastic constants decrease while the damping capacity improve when MBS rubber was added in the range up to 9 phr.
The Robust Design with Column Merging Method for the Optimal Design of Low Noise Intake System
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 10, 2002, Pages 773~784
DOI : 10.5050/KSNVN.2002.12.10.773
This paper proposes an optimal design to improve the performance of the intake system by reducing the noise. We adapt the Taguchi method and column merging method for the above design. At the first stage of the design, the length and radius of each component of the current intake system are selected as control factors. Then the
table of orthogonal array is used to get the effective main factors. At the second stage, the
table of orthogonal array and the column merging method is combined to analyze subdivided significant factors. We know that the robust design with the column merging method provides better design for noise of intake system than the robust design itself.
Dynamic Characteristic Analysis of Trapezoidal Cantilever Plates Undergoing Translational Acceleration
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 10, 2002, Pages 785~791
DOI : 10.5050/KSNVN.2002.12.10.785
A modeling method for the dynamic characteristic analysis of a translationally accelerated trapezoidal cantilever plate is presented in this paper. The equations of motion for the plate are derived and transformed into a dimensionless form. The effects of the inclination angles and the acceleration on the vibration characteristics of the plate are investigated. Incidentally, natural frequency loci veering and associated mode shape variations are observed and discussed.
The Improvement of Multi-dof Impulse Response Spectrum by Using Optimization Technique
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 10, 2002, Pages 792~798
DOI : 10.5050/KSNVN.2002.12.10.792
The spectrum of impulse response signal from an impulse hammer testing is widely used to obtain frequency response function (FRF) of the structure. However the FRFs obtained from impact hammer testing have not only leakage errors but also finite record length errors when the record length for the signal processing is not sufficiently long. The errors cannot be removed with the conventional signal analyzer which treats the signals as if they are always steady and periodic. Since the response signals generated by the impact hammer are transient and have damping, they are undoubtedly non-periodic. It is inevitable that the signals be acquired for limited recording time, which causes the finite record length error and the leakage error. In this paper, the errors in the frequency response function of multi degree of freedom system are formulated theoretically. And the method to remove these errors is also suggested. This method is based on the optimization technique. A numerical example of 3-dof model shows the validity of the proposed method.
Fault Diagnostics Algorithm of Rotating Machinery Using ART-Kohonen Neural Network
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 10, 2002, Pages 799~807
DOI : 10.5050/KSNVN.2002.12.10.799
The vibration signal can give an indication of the condition of rotating machinery, highlighting potential faults such as unbalance, misalignment and bearing defects. The features in the vibration signal provide an important source of information for the faults diagnosis of rotating machinery. When additional training data become available after the initial training is completed, the conventional neural networks (NNs) must be retrained by applying total data including additional training data. This paper proposes the fault diagnostics algorithm using the ART-Kohonen network which does not destroy the initial training and can adapt additional training data that is suitable for the classification of machine condition. The results of the experiments confirm that the proposed algorithm performs better than other NNs as the self-organizing feature maps (SOFM) , learning vector quantization (LYQ) and radial basis function (RBF) NNs with respect to classification quality. The classification success rate for the ART-Kohonen network was 94 o/o and for the SOFM, LYQ and RBF network were 93 %, 93 % and 89 % respectively.
Nonlinear Dynamic Characteristics of Deployable Missile Control Fin
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 10, 2002, Pages 808~815
DOI : 10.5050/KSNVN.2002.12.10.808
The nonlinear characteristics for hinge of a deployable missile control fin are investigated experimentally. The nonlinearity is caused by a worn or loose hinge and manufacturing tolerance and cannot be eliminated completely. The structural nonlinearity has an effect on the static and dynamic characteristics of the control fin. Therefore, it is necessary to establish the accurate nonlinear model for the hinge of the control fin. In the present study the existence of nonlinearities in the hinge is confirmed from the frequency response experiments such as tip random excitation and base sine sweep. Using the system identification method. especially, ″Force-state Mapping Technique″, the types of nonlinearities are identified and the nonlinear hinge model of the control fin is established.