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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 14, Issue 12 - Dec 2004
Volume 14, Issue 11 - Nov 2004
Volume 14, Issue 10 - Oct 2004
Volume 14, Issue 8 - Aug 2004
Volume 14, Issue 7 - Jul 2004
Volume 14, Issue 6 - Jun 2004
Volume 14, Issue 5 - May 2004
Volume 14, Issue 4 - Apr 2004
Volume 14, Issue 9 - Mar 2004
Volume 14, Issue 3 - Mar 2004
Volume 14, Issue 2 - Feb 2004
Volume 14, Issue 1 - Jan 2004
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Real-time Active Vibration Control of Smart Structure Using Adaptive PPF Controller
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 267~275
DOI : 10.5050/KSNVN.2004.14.4.267
This research is concerned with the development of a real-time adaptive PPF controller for the active vibration suppression of smart structure. In general, the tuning of the PPF controller is carried out off-line. In this research, the real-time learning algorithm is developed to find the optimal filter frequency of the PPF controller in real time and the efficacy of the algorithm is proved by implementing it in real time. To this end, the adaptive algorithm is developed by applying the gradient descent method to the predefined performance index, which is similar to the method used popularly in the optimization and neural network controller design. The experiment was carried out to verify the validity of the adaptive PPF controller developed in this research. The experimental results showed that adaptive PPF controller is effective for active vibration control of the structure which is excited by either impact or harmonic disturbance. The filter frequency of the PPF controller is tuned in a very short period of time thus proving the efficiency of the adaptive PPF controller.
Comparing Highway Traffic Noise Emission Levels Using Individual UofL State - specific Data - Based on Open Space -
Teak K. ; Roswell A. Harris ; Louis F. Cohn ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 276~286
DOI : 10.5050/KSNVN.2004.14.4.276
Inertia Latch Design for Micro Optical Disk Drives
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 287~294
DOI : 10.5050/KSNVN.2004.14.4.287
Dynamic Load/unload (L/UL) mechanism is an alternative to the contact start stop (CSS) technology which eliminates striction and wear failure modes associated with CSS. Inertia latch mechanism becomes important for mobile disk drives because of non operating shock performance. Various types of latch designs have been introduced in hard disk drives to limit a rotary actuator from sudden uncontrolled motion. In this paper, a single spring inertia latch is introduced for a small form optical disk drive, which uses a rotary actuator for moving an optical pick-up. A new small inertia latch with sin91e spring is designed to ensure both feasible and small size. The shock performance of the new inertia latch is experimentally verified.
Optimal Design of a Near-field Optical Recording Suspension
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 295~302
DOI : 10.5050/KSNVN.2004.14.4.295
In this study the optimization of a NFR suspension is performed using finite element method and experimental modal analysis. NFR suspensions are required to have low compliance modes to allow the slider to comply with the rotating disk, and high tracking stiffness modes to maximize the servo bandwidth of the tracking controller First of all, the dual suspension model is designed based on the characteristics of NFR drives. And the parametric study on the sensitivities of compliance modes and tracking stiffness modes is investigated. Finally, the model satisfying static characteristics is selected and shape optimization is performed to improve dynamic characteristics. A prototype of a NFR suspension is made by etching and modal ekperiment in free state is performed. The results of experiment almost agree with those of finite element method.
A Method to Arrange Absorptive Materials on Walls for Effective Interior Noise Control
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 303~309
DOI : 10.5050/KSNVN.2004.14.4.303
Absorptive material arrangement method for effective interior noise control is proposed. Sound field with arbitrary boundary condition is formulated by Kirchhoff-Helmholtz integral equation. A simple example such as a rectangular cavity will present physical meaning between changing boundary condition and control of sound field. The effect of changing boundary condition is expressed in modal admittance. From this formulation. an admittance map is presented. The admittance map is the figure to represent position where absorptive material is attached for effective interior noise control. The admittance map can be assigned to each resonant frequency. There. however, may be common area of those maps. Then, frequency robust arrangement of absorptive material in noise control will be presented.
Internal Aerodynamic Noise from Quick Opening Throttle Valve
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 310~318
DOI : 10.5050/KSNVN.2004.14.4.310
For many industrial problems originating from aerodynamic noise, noise prediction techniques, reliable and easy to apply, would be of great value to engineers and manufacturers. General algorithm is presented for the prediction of internal flow-induced noise from quick opening throttle valve in an automotive engine. This algorithm is based on the integral formula derived by using the General Green Function, Lighthill's acoustic analogy and Curle's extension of Lighthill's. Novel approach of this algorithm is that the integral formula is so arranged as to predict frequency-domain acoustic signal at any location in a duct by using unsteady flow data in space and time, which can be provided by the Computational Fluid Dynamics Techniques. This semi-analytic model is applied to the prediction of internal aerodynamic noise from a throttle valve in an automotive engine. The predicted noise levels from the throttle valve show good agreement with actual measurements. The results show that the dipole noise is dominant in this phenomena and the origin of noise sources is attributed to the anti-vortex lines formed in the down-stream from a throttle valve. This illustrative computation shows that the current method permits generalized predictions of flow noise generated by bluff bodies and turbulence in flow ducts.
Virtual Acoustics Field Simulation System for the Soundscape Reproduction in Public
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 319~326
DOI : 10.5050/KSNVN.2004.14.4.319
The soundscape is a novel attempt to offer comfortable sound environments at the urban public spaces by adding pleasant sounds and removing unagreeable ones. Most important factors to be considered therein are to determine what kind of sounds to offer and how to adjust them to the changing circumstances. But, installing, maintaining and adjusting the soundscape system directly in the field will ensue numerous problems as well as high costs. Thus, it is essential to devise a test method to analyse and verify the outcome before the actual installation in the field takes place. This study aims at devising the instrument system that enables to control. with a great ease, numerous variables. reproduce most agreeable sound sources, and can verify the effects on the virtual simulatory settings, which is named as Virtual Acoustic Field Simulation System (VAFSS).
Fretting-wear Characteristics of Steam Generator Helical Tubes
Jong Chull Jo ; Woong Sik Kim ; Hho Jung Kim ; Tae Hyung Kim ; Myung Jo Jhung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 327~335
DOI : 10.5050/KSNVN.2004.14.4.327
This study investigates the safety assessment of the potential for fretting-wear damages caused by foreign object in operating nuclear power plants. To get the natural frequency, corresponding mode shape and participation factor, modal analyses are performed for the helical type tubes with various conditions. The wear rate of helical type tube caused by foreign object is calculated using the Archard formula and the remaining life of the tube is predicted, and discussed in this study is the effect of the vibration of the tube on the remaining life of the tube. In addition, addressed is the effect of the external pressure on the vibration and fretting-wear characteristics of the tube.
Flexural Vibrations of Rectangular Plates Having V-notches or Sharp Cracks
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 336~343
DOI : 10.5050/KSNVN.2004.14.4.336
This paper reports the first known free vibration data for thin rectangular plates with V-notches. The classical Ritz method is employed with two sets of admissible functions assumed for the transverse vibratory displacements. These sets include (1) mathematically complete algebraic-trigonometric polynomials which guarantee convergence to exact frequencies as sufficient terms are retained, and (2) corner functions which account for the bending moment singularities at the sharp reentrant corner of the Y-notch. Extensive convergence studies summarized herein confirm that the corner functions substantially enhance the convergence and accuracy of nondirectional frequencies for rectangular plates having the V-notch. In this paper, accurate frequencies and normalized contours of vibratory transverse displacement are presented for various notched plates, so that the effect of corner stress singularities may be understood.
Study on the Prevention of Pad Fluttering with the Variation of Preload in a Tilting Pad Journal Bearing
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 344~351
DOI : 10.5050/KSNVN.2004.14.4.344
Tilling pad journal bearings have been widely used to support the rotors of the high rotating machinery such as steam and gas turbines owing to their inherent dynamic stability characteristics. However, serious bearing problems such as fatigue damage in the upper unloaded pad, the break of locking pins and the wear of pinholes etc. by pad fluttering are frequently taken place in the actual steam turbines. The purpose of this paper is to investigate the mechanism of pad fluttering and to suggest the useful design guideline(application of preload, m) for the purpose of preventing bearing problems by pad fluttering in a tilting pad journal bearing. It is estimated that upper pad is easy to flutter because the film shape of the upper pad is diverged by moment acting on pivot point. This paper suggests that effective preload range(m
0.5) in order to be statically loaded pad under all operating conditions. Also, design modified bearing is suggested for the adjustment in actual steam turbines. And bearing and rotor dynamic analysis are performed to identify bearing characteristics and to verify the reliability of rotor-bearing system.
Particle Velocity and Intensity Estimation Error in Spatial Discrete Domain
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 4, 2004, Pages 352~357
DOI : 10.5050/KSNVN.2004.14.4.352
This paper studies the errors that associated with particle velocity and intensity in a space. We theoretically derived their bias error and random error. The analysis shows that the more samples do not always guarantee the better results. The random error of the velocity and intensity are increased when we have many samples. The characteristics of the amplification of the random error are analyzed in terms of the sample spacing. The amplification was found to be related to the spatial differential of random noise. The numerical simulations are performed to verify theoretical results.