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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 13, Issue 12 - Dec 2003
Volume 13, Issue 11 - Nov 2003
Volume 13, Issue 10 - Oct 2003
Volume 13, Issue 9 - Sep 2003
Volume 13, Issue 8 - Aug 2003
Volume 13, Issue 7 - Jul 2003
Volume 13, Issue 6 - Jun 2003
Volume 13, Issue 5 - May 2003
Volume 13, Issue 4 - Apr 2003
Volume 13, Issue 3 - Mar 2003
Volume 13, Issue 2 - Feb 2003
Volume 13, Issue 1 - Jan 2003
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Optimization of the Number and Position of Far Field Sources in Using the Equivalent Source Method
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 743~750
DOI : 10.5050/KSNVN.2003.13.10.743
The equivalent source method(ESM) is used for the calculation of the internal pressure field for an enclosure which can have arbitrary boundary conditions and nay include internal objects which scatter the sound field. The advantage of using ESM is that it requires relatively low computing cost and is easy to model the internal diffracting objects. Typical ESM modeling uses two groups of equivalent source positions. One group includes the first order images of the source inside the enclosure. The Positions of the other group are usually on a spherical surface some distance outside the enclosure. The normal velocity on the surfaces of the enclosure walls is evaluated at a larger number of positions than there are equivalent sources. The sum of the squared difference between this velocity and the expected is minimized by adjusting the strength of the equivalent sources. This study is on the optimal far field sources positions when using the equivalent source method. In general, the far field sources are evenly distributed on a surface of a virtual sphere which is centered at the enclosure with a sufficiently large radius. In this study. optimal far field source locations are searched using simulated annealing method for various radii of spheres where far field sources are located. Simulation results showed that optimally located sources with adequate distance away from the enclosure center gave better result than sources with even distribution even with a smaller number of far field sources.
Vibration of Liquid-filled Cylindrical Storage Tank with an Annular Plate Cover
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 751~759
DOI : 10.5050/KSNVN.2003.13.10.751
The theoretical method is developed to investigate the vibration characteristics of the sloshing and bulging mode for the circular cylindrical storage tank with an annular plate on free surface. The cylindrical tank is filled with an inviscid and incompressible liquid. The liquid domain is limited by a rigid cylindrical surface and a rigid flat bottom. As the effect of free surface waves Is taken into account in the analysis, the bulging and sloshing modes are studied. The solution for the velocity potential of liquid movement is assumed as a suitable harmonic function that satisfies Laplace equation and the relevant boundary conditions. The Rayleigh-Ritz method is used to derive the frequency equation of the cylindrical tank. The effect of Inner-to-outer radius ratio and thickness of annular plate and liquid volume on vibration characteristics of storage tank is studied. The finite element analysis is performed to demonstrate the validity of present theoretical method.
Vibration Suppression Using Eddy Current Damper
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 760~766
DOI : 10.5050/KSNVN.2003.13.10.760
This paper is concerned with the eddy current damper which can be used to enhance the damping of the host structure. The operating principle of the eddy current damper is first explained in detail. The dynamic interaction between the magnets and the copper plate produces eddy current thus resulting in the damping force. By attaching the eddy current damper to the host structure, the damping of the total structure can be increased so that vibrations can be suppressed. The advantage of the eddy current damper is that it doesn't require any electronic devices and power supply The effect of the eddy current damper on the global dynamic characteristics of the structure is investigated by considering the cantilever with the eddy current damper. Experimental results show that the eddy current damper is an effective device for vibration suppression.
Vibration Analysis of Combined Cylindrical Shells with an Annular Plate
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 767~776
DOI : 10.5050/KSNVN.2003.13.10.767
The theoretical method is developed to Investigate the nitration characteristics of the combined cylindrical shells with an annular plate joined to the shell at any arbitrary axial position. The structural coupling between shell and plate is simulated using two types of artificial springs a translational spring is introduced for translational coupling and a rotational spring is used for rotational coupling. The springs are continuously distributed along circumferential direction. Using the Rayleigh-Ritz method the natural frequencies and mode shapes of the combined shell with an annular plate examine. The effect of Inner-to-outer radius ratio, axial position of annular plate and length-to-radius ratio of shell on vibration characteristics of combined cylindrical shells is studied. The theoretical results are verified by comparison with FEM results.
Reduction Method of Acoustic Vibrating Plate Using Piezo Electric Material
Jung, Do-Hee ; Park, Seen-Ok ; Kim, Woo-Young ; Lee, Sang-Kee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 777~784
DOI : 10.5050/KSNVN.2003.13.10.777
Acoustic response control of a corner-pinned plate using piezoelectric wafers was studied, both theoretically and experimentally Three different sizes of aluminum alloy plates were used and available ball joints were employed to hold the plate at the four corners. The plate with the largest aspect ratio showed the largest and most clear responses to the acoustic excitation in the range of frequencies (0∼200 Hz), and sound pressure levels (80∼100 dB) as predicted. The reduction of the acoustic response of the plate by piezoelectric actuator was very significant, more than expected, but abatement of the sound transmission through the plate was only slightly altered by the piezoelectric actuator. This work is an original work extending earlier work with doors excited by acoustic fields. The important difference is the used of ball joints to simulate the joints.
Optimal Design of Optical Flying Head for Near-field Recording
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 785~790
DOI : 10.5050/KSNVN.2003.13.10.785
This paper presents an approach to optimally design the air-hearing surface (ABS) of the optical flying head for near-field recording technology (NFR) NFR is an optical recording technology using very small beam spot size by overcoming the limit of beam diffraction. One of the most important problems in NFR Is a head disk interface (HDI) issue over the recording band during the operation. A multi-criteria optimization problem is formulated to enhance the flying performances over the entire recording band during the steady state. The optimal solution of the slider, whose target flying height is 50 nm, is automatically obtained. The flying height during the steady state operation becomes closer to the target values than those for the Initial one. The pitch and roll angles are also kept within suitable ranges over the recording band. Especially. all of the all-hearing stiffness are drastically increased by the optimized geometry of the air hearing surface.
Numerical Analysis of Vibration Characteristics in Deep Water Tank
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 791~797
DOI : 10.5050/KSNVN.2003.13.10.791
A liquid storage rectangular tank structures are used In many fields of civil, mechanical and marine engineering. Especially, Ship structures have many tanks In contact with Inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine or propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tank structures. In the previous report, we have developed numerical tool of vibration analysis of 3-dimensional tank structure using finite elements for plates and boundary elements for fluid region. In the present report, using the numerical analysis, vibrations characteristics In deep water tank are investigated and discussed.
An Experimental Study on the Vibration of the PWR Fuel Rod Supported by the Side-sloted Plate Springs
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 798~804
DOI : 10.5050/KSNVN.2003.13.10.798
One of the methods that are used to compare and verify the supporting performance of the spacer grids developed is the vibration characteristic test. A modal test in this paper is performed for a dummy rod 3,847 mm tall supported by eight New Doublet (ND) spacer grids. For the vibration test in air, nine accelerometers, one displacement sensor and one shaker are used for acquiring signals, and an I-DEAS TDAS software Is employed for analyzing the signals. Also, a finite element (FE) analysis is performed by a beam-spring simple model and a contact model simulating the contact phenomenon between the rod and the ND spring. And then, the results of the modal testing are compared with those of the FE analysis. The natural frequencies as well as the mode shapes obtained by the experiment have a greater similarity to the results by the contact model than the previous beam-spring model. In audition, for grasping whether or not the modal parameters are influenced by where shaking spot is, two kinds of tests are performed : one is for the shaker attached at the fourth span (center), the other is for the shaker at the fifth span that is one span nearer to the bottom of the rod. The latter shows higher MAC than the former Finally, the vibration displacements are measured in the range of 0.l12∼0.214 mm for the excitation force of 0.25∼0.75 N.
Analysis of Dynamic Characteristics of a HDD Spindle System Supported by Ball Bearing Due to Temperature Variation
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 805~812
DOI : 10.5050/KSNVN.2003.13.10.805
This paper presents a method to investigate the characteristics of a ball bearing and the dynamics of a HDD spindle system due to temperature variation. Finite element model is developed for the rotating and stationary parts of a HDD spindle system separately to determine their thermal deformations by using ANSYS, a finite element program. Then, the relative position of the rotating part with respect to the stationary part is determined by solving the equilibrium equation of the contact force between upper and lower ball bearings. The validity of the proposed method is verified by comparing the theoretical natural frequencies of a HDD spindle system with the experimental ones before and after temperature variation. It shows that the elevated temperature results in the increase of contact angle and the decrease of bearing deformation, contact force and bearing stiffness, which result in the decrease of the natural frequencies of a HDD spindle system.
Generalized Modal Analysis of Asymmetrical Rotor System Using Modulated Coordinates
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 813~820
DOI : 10.5050/KSNVN.2003.13.10.813
Conventional modal analysis techniques are known to be inappropriate for asymmetrical rotor systems, when the equations of motion are written in the stationary coordinates, due to the presence of time varying parameters. This paper presents a generalized modal analysis method for asymmetrical rotor systems in the stationary coordinates, employing the modulated coordinates and the lambda matrix formulation. A numerical example with a flexible asymmetric rotor model is provided to demonstrate the effectiveness of the proposed modal analysis method. As an application of the proposed method, modal analysis is also performed with an open cracked rotor system.
Free Vibration Analysis of Arbitrarily Shaped Plates with Free Edges Using Non-dimensional Dynamic Influence Functions
Transactions of the Korean Society for Noise and Vibration Engineering, volume 13, issue 10, 2003, Pages 821~827
DOI : 10.5050/KSNVN.2003.13.10.821
The so-called boundary node method (or NDIF method) that was developed by the authors has been extended for free vibration analysis of arbitrarily shaped plates with free edges. Since the proposed method requires no interpolation functions. no integration Procedure is needed on boundary edges of the plates and only a small amount of numerical calculation is involved, compared with FEM and BEM. In order to explain tile reason why spurious eigenvalues are generated when the NDIF method is applied to free plates, the NDIF method has been considered for free vibration analysis of both a fixed string and a free beam. Finally, verification examples show that natural frequencies obtained by the present method agree well with those given by an exact method or a numerical method (ANSYS).