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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 19, Issue 12 - Dec 2009
Volume 19, Issue 11 - Nov 2009
Volume 19, Issue 10 - Oct 2009
Volume 19, Issue 9 - Sep 2009
Volume 19, Issue 8 - Aug 2009
Volume 19, Issue 7 - Jul 2009
Volume 19, Issue 6 - Jun 2009
Volume 19, Issue 5 - May 2009
Volume 19, Issue 4 - Apr 2009
Volume 19, Issue 3 - Mar 2009
Volume 19, Issue 2 - Feb 2009
Volume 19, Issue 1 - Jan 2009
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Flow-induced Vibration(FIV) Analysis of a 3D Axial Compressor Blade
Kim, Dong-Hyun ; Kim, Yu-Sung ; Yang, Guo Wei ; Jung, Kyu-Kang ; Kim, Kyung-Hee ; Min, Dae-Gee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 551~559
DOI : 10.5050/KSNVN.2009.19.6.551
In this study, flow-induced vibration(FIV) analyses have been conducted for a 3D compressor blade model. Advanced computational analysis system based on computational fluid dynamics(CFD) and computational structural dynamics(CSD) has been developed in order to investigate detailed dynamic responses of designed compressor blades. Fluid domains are modeled using the computational grid system with local grid deforming and remeshing techniques. Reynolds-averaged Navier-Stokes equations with
turbulence model are solved for unsteady flow problems of the rotating compressor model. A fully implicit time marching scheme based on the Newmark direct integration method is used for computing the coupled aeroelastic governing equations of the 3D compressor blade for fluid-structure interaction(FSI) problems. Detailed dynamic responses and instantaneous pressure contours on the blade surfaces considering flow-separation effects are presented to show the multi-physical phenomenon of the rotating compressor blade.
Modal Vibration Characteristics of an Annular Disk Containing Evenly Spaced Narrow Radial Slots
Lee, Hyeong-Ill ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 560~568
DOI : 10.5050/KSNVN.2009.19.6.560
Modal vibration characteristics of a thin annular disk containing narrow radial slots are studied numerically and experimentally. Existing analytical solution is examined based on these results revealing that it can not precisely predict eigenvalues of the disk with slots since it does not accurately consider change in the vibration modes and change in strain energy density distributions due to the slots. Parametric study on slot length found that distortions in the mode shape as well as changes in the corresponding natural frequencies are proportional to the slot length. Consequently, errors in the calculated eigenvalues are also proportional to the slot length and accurate data can not be obtained with existing analytical solution above a certain level of slot length. Same phenomena can be observed in both free-free disk and fixed-free disk.
Effect of External Damping and Tip Mass on Dynamic Stability of Pipes Conveying Fluid
Kim, H.J. ; Ryu, B.J. ; Jung, S.H. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 569~574
DOI : 10.5050/KSNVN.2009.19.6.569
The paper presents the influences of the external damping and the tip mass on dynamic stability of a vertical cantilevered pipe conveying fluid. In general, real pipe systems may have some valves and attached mechanical parts, which can be regarded as attached lumped masses and support-dampers. The support-dampers can be assumed as viscous dampers. The equations of motion are derived by energy expressions using extended Hamilton`s principle, and some numerical results using Galerkin`s method are presented. Critical flow velocities and stability maps of the pipe with external dampers and tip mass are obtained for various tip mass ratios, external damping coefficients and positions of the viscous dampers.
Extraction of Bridge Flutter Derivatives by a Forced Excitation
Lee, Seung-Ho ; Kwon, Soon-Duck ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 575~582
DOI : 10.5050/KSNVN.2009.19.6.575
This study presents the vibration excitation system to extract the aerodynamic stability derivatives which is generally called as flutter derivatives in civil engineering. The system consists of the excitation part to give a forced harmonic motion to the model and the sensing part to measure the aerodynamic forces as well as inertia forces acting on a bridge model. A data processing algorithm for extracting the flutter derivatives from the measured forces is also presented. From the wind tunnel tests, verification of present system was done by comparing the measured and analytical results for rectangular shaped model. The effects of excitation frequencies and amplitudes on flutter derivatives are discussed. Five kinds of actual bridge model were presented from the wind tunnel.
A New Type of Active Engine Mount System Featuring MR Fluid and Piezostack
Lee, Dong-Young ; Sohn, Jung-Woo ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 583~590
DOI : 10.5050/KSNVN.2009.19.6.583
An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds(wide frequency range) and presented in time domain.
Extension of Rational Interpolation Functions for FE Analysis of Rotating Beams
Kim, Yong-Woo ; Jeong, Jae-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 591~598
DOI : 10.5050/KSNVN.2009.19.6.591
Starting from the rotating beam finite element in which the interpolating shape functions satisfy the governing static homogeneous differential equation of Euler-Bernoulli rotating beams, we derived new shape functions that satisfy the governing differential equation which contains the terms of hub radius and setting angle. The shape functions are rational functions which depend on hub radius, setting angle, rotational speed and element position. Numerical results for uniform and tapered cantilever beams with and without hub radius and setting angle are compared with the available results. It is shown that the present element offers an accurate method for solving the free vibration problems of rotating beams.
Reduction of Fire Main Pipe System`s Vibration Using Back Flow Prevent Globe Valve
Park, Mi-You ; Han, Hyung-Suk ; Lee, Seuk-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 599~606
DOI : 10.5050/KSNVN.2009.19.6.599
Main source of URN(underwater radiated noise) which is related to the ship`s survivability is divided into two groups. Cavitation is the main source of URN when the speed of ship is upper than CIS(cavitation inception speed). But when the speed of ship is lower than CIS, the main source of URN is the structure-borne noise on the hull which is originated from propulsion system, pump system and trnasmitted vibration of the pipe system. In this paper, to reduce the vibration of discharge pipe and valve system, back flow prevent globe valve and new rubber mount are applied to the ship. As the result of applying new valve and mount, the vibration is reduced drastically.
A Formulation of NDIF Method to the Algebraic Eigenvalue Problem for Efficiently Extracting Natural Frequencies of Arbitrarily Shaped Plates with the Simply Supported Boundary Condition
Kang, S.W. ; Kim, J.G. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 607~613
DOI : 10.5050/KSNVN.2009.19.6.607
A new formulation of NDIF method to the algebraic eigenvalue problem is introduced to efficiently extract natural frequencies of arbitrarily shaped plates with the simply supported boundary condition. NDIF method, which was developed by the authors for the free vibration analysis of arbitrarily shaped membranes and plates, has the feature that it yields highly accurate natural frequencies compared with other analytical methods or numerical methods(FEM and BEM). However, NDIF method has the weak point that it needs the inefficient procedure of searching natural frequencies by plotting the values of the determinant of a system matrix in the frequency range of interest. A new formulation of NDIF method developed in the paper doesn`t require the above inefficient procedure and natural frequencies can be efficiently obtained by solving the typical algebraic eigenvalue problem. Finally, the validity of the proposed method is shown in several case studies, which indicate that natural frequencies by the proposed method are very accurate compared to other exact, analytical, or numerical methods.
Design of Spindle Motor-chuck System for Ultra High Resolution
Kim, Kyung-Ho ; Kim, Ha-Yong ; Shin, Bu-Hyun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 614~619
DOI : 10.5050/KSNVN.2009.19.6.614
The STW(servo track writing) system which is the process of writing servo signals on disks before assembling in drives uses the spindle motor-chuck mechanism to realize low cost because the spindle motor-chuck mechanism has merit which can simultaneously write multi-disk by piling up disks in hub. Therefore, when the spindle motor-chuck mechanism of horizontal type operates in high rotation speed it is necessary to reduce the effect of RRO(repeatable run-out) and NRRO(non-repeatable run-out) to achieve the high precision accuracy of nano-meter level during the STW process. In this paper, we analyzed that the slip in assembly surfaces can be caused by the mechanical tolerance and clamping force in hub-chuck mechanism and can affect NRRO performance. We designed springs for centering and clamping considering centrifugal force by the rotation speed and assembly condition. The experimental result showed NRRO performance improves about 30 % than case of weak clamping force. The result shows that the optimal design of the spindle motor-chuck mechanism can effectively reduce the effect of NRRO and RRO in STW process.
Dynamic Characteristics of Tuned Liquid Column Dampers Using Shaking Table Test
Min, Kyung-Won ; Park, Eun-Churn ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 620~627
DOI : 10.5050/KSNVN.2009.19.6.620
Shaking table test was carried out to obtain dynamic characteristics of TLCDs with uniform and non-uniform sections for both horizontal and vertical tubes. The input to the table is harmonic acceleration with constant magnitude. The output is horizontal dynamic force which is measured by load cell installed below the TLCD. Transfer functions are experimentally obtained using the ratio of input and output. Natural frequency, the most important design factor, is compared to that by theoretical equation for TLCDs with five different water levels. System identification process is performed for experimentally obtained transfer functions to find the dynamic characteristics of head loss coefficient and effective mass of TLCDs. It is found that their magnitudes are larger for a TLCD with non-uniform section than with uniform section and natural frequencies are close to theoretical ones.
A Study on the Sound Absorption Performance of a Helmholtz Resonator Combined with Porous Materials
Lee, Dong-Hoon ; Song, Hwa-Young ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 628~633
DOI : 10.5050/KSNVN.2009.19.6.628
The helmholtz resonator with the perforated neck has demerits that the absorption performance is not so outstanding in an anti-resonance frequency and high frequency bandwidth. In order to overcome these problems, in the paper, a resonator combined with porous material is proposed. The absorption performances of resonators are measured by two-microphone method and estimated by transfer matrix method. The experimentally measured values of normal absorption coefficients agree well with the corresponding values from the transfer matrix method. Because of the porous material, it is shown that the absorption performance have been significantly improved in the anti-resonance frequency and high frequency bandwidth.
Effect of Leakage on the Noise Reduction Characteristics of Helmholtz Resonator
Lee, Il-Jae ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 19, issue 6, 2009, Pages 634~640
DOI : 10.5050/KSNVN.2009.19.6.634
Helmholtz resonator has been used, especially in intake and exhaust systems of vehicles, due to its good noise reduction characteristics at low frequencies. Many approaches have been developed to predict the acoustic behavior of the resonator with the assumption that there is no leakage from the resonator. However, its behavior may be affected by leakage which may exist in manufacturing processes or on purpose. This study investigates the effect of leakage on the noise reduction characteristics of Helmholtz resonator with two practical examples. One is a resonator with a gap between baffle and housing of the resonator and the other one is a resonator with two drain holes on the baffle. The measured transmission loss shows that the resonance frequencies are considerably shifted to higher frequency due to the leakage. The Boundary Element Method was applied to predict the transmission loss of the Helmholtz resonator with drain holes. The comparison between the measured and predicted transmission loss shows that the acoustic impedance of the holes is essential for accurate predictions of the transmission loss.