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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 16, Issue 12 - Dec 2006
Volume 16, Issue 11 - Nov 2006
Volume 16, Issue 10 - Oct 2006
Volume 16, Issue 9 - Sep 2006
Volume 16, Issue 8 - Aug 2006
Volume 16, Issue 7 - Jul 2006
Volume 16, Issue 6 - Jun 2006
Volume 16, Issue 5 - May 2006
Volume 16, Issue 4 - Apr 2006
Volume 16, Issue 3 - Mar 2006
Volume 16, Issue 2 - Feb 2006
Volume 16, Issue 1 - Jan 2006
Selecting the target year
Vibration Characteristics of a Railway Depot : Practical Approach
Kim, Jung-S. ; Son, Jung-S. ; Kim, Jeung-T. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 219~225
DOI : 10.5050/KSNVN.2006.16.3.219
In Seoul, several railway depots are located at the places where a public can easily access. Since a depot occupy a large amount of land itself, it is natural to use those sites for a public building construction such as an apartment complex or a transportation terminal, as an example. Most of the buildings on a depot, however, are exposed to vibration problems, because foundations are excited from the dynamic loading whenever heavy trains pass on the track. Severe vibration may cause a damage to building structures and a troublesome to a community. In this paper, some vibration practices have been examined in order to resolve the vibration problems. First, a critical speed of a train in a railway depot is evaluated. Then, the structural effect has been investigated. Finally, practical approaches to reduce the vibration level have been proposed. In this first half part of the paper, the focus has been on the critical speed and a structural transmission phenomena.
Dynamic Analysis of an Impulsively Forced Rotating Cantilever Beam
Lim, Hong-Seok ; Yoo, Hong-Hee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 226~232
DOI : 10.5050/KSNVN.2006.16.3.226
This paper presents the dynamic analysis of an impulsively forced rotating cantilever beam with rigid body motion. The transient response induced by the impulsive force and the rigid body motion of the beam are calculated using hybrid deformation variable modeling with the Rayleigh-Ritz assumed mode methods. The stiffness variation effect due to the rigid body motion of the beam is considered in this study Also, the effects of the impulsive force position and the angular velocity on the transient responses of the beam are investigated through numerical works.
Effect of the Joint Condition between Muffler Shell and Baffle on Radiated Noise
Yang, Chul-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 233~239
DOI : 10.5050/KSNVN.2006.16.3.233
The effect of the joint condition of automotive muffler shell and baffle on radiated noise from muffler shell Is studied. Shell vibration characteristics, especially shift In natural frequency and change in of response amplitude, was identified from finite element analysis and modal tests for various joint conditions between shell and baffle. When there is heat expansion and inner pressure from the exhaust 9as in the muffler with elliptical cross section, the shell expands out, and construct gap with baffles. This gap causes more degrees of freedom of shell vibration and natural frequency shift. By welding the muffler shell to the baffles or using a dual shell muffler, the radiated noise problem could be mitigated supplying more a rigid joint and damping, respectively.
Analyzing for Refrigerant Induced Noise for Split Type Air Conditioner Indoor Unit
Aoyama Shigeo ; Mo, Jin-Yong ; Lee, Jae-Kwon ; Song, Yong-Jae ; Han, Hyung-Suk ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 240~246
DOI : 10.5050/KSNVN.2006.16.3.240
In the air-conditioner, refrigerant induced noise and vibration can be increased when the airflow rate is reduced in order to decrease the noise at the low mode. Through the test and analysis of this kind of noise, it can be verified that the main reasons of refrigerant induced noise are the velocity and flow Induced force of the refrigerant at the inlet of the evaporator, So, in order to reduce this velocity, quality at the evaporator inlet should be minimized. And, in order to reduce flow induced force of the refrigerant, sudden change of fluid flow must not be occurred. So, in this paper, we will review the characteristics of refrigerant cycle and find how the quality and flow induced force can be minimized.
Vibration Analysis and Critical Speeds of Rotating Polar Orthotropic Disks, Part II : Analysis Results
Koo, Kyo-Nam ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 247~254
DOI : 10.5050/KSNVN.2006.16.3.247
This paper (Part II) provides the application results of the method presented in a companion paper (Part I) where the dynamic equation for rotating polar orthotropic disk is formulated and its solution method is considered. The natural frequencies and critical speed of polycarbonate CD are calculated to validate the present method and are shown to by very accurate. The critical speeds of typical GFRP and CFRP CD`s are computed by aligning the fibers in radial and circumferential directions. The radially reinforced CFRP CD is shown to have the five times higher critical speed than that of the polycarbonate CD. The natural frequencies and critical speeds of disks with various elastic modulus ratios are obtained. The results show that the radially reinforced disk is more effective in increasing critical speed than the circumferentially reinforced disk.
Study on the Nonstationary Behavior of Slider Air Bearing Using Reassigned Time -frequency Analysis
Jeong, Tae-Gun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 255~262
DOI : 10.5050/KSNVN.2006.16.3.255
Frequency spectrum using the conventional Fourier analysis gives adequate information about the dynamic characteristics of the slider air bearing for the linear and stationary cases. The intermittent contacts for the extremely low flying height, however, generate nonlinear and nonstationary vibration at the instant of contact. Nonlinear dynamic model should be developed to simulate the impulse response of the air bearing during slider-disk contact. Time-frequency analysis is widely used to investigate the nonstationary signal. Several time-frequency analysis methods are employed and compared for the slider vibration signal caused by the impact against an artificially induced scratch on the disk. The representative Wigner-Ville distribution leads to the severe interference problem by cross terms even though it gives good resolution both in time and frequency. The smoothing process improves the interference problem at the expense of resolution. In order to get the results with good resolution and little interference, the reassignment method is proposed. Among others the reassigned Gabor spectrogram shows the best resolution and readability with negligible interference.
Time-domain Computation of Broadband Noise due to Turbulence - cascade Interaction
Jung, Sung-Soo ; Cheung, Wan-Sup ; Lee, Soo-Gab ; Cheong, Cheol-Ung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 263~269
DOI : 10.5050/KSNVN.2006.16.3.263
The objective of the present work is to develop a time-domain numerical method of broadband noise in a cascade of airfoils. This paper focuses on dipolar broadband noise sources, resulting from the interaction of turbulent inflows with the flat-plate airfoil cascade. The turbulence response of a two-dimensional cascade is studied by solving both of the linearised and the full nonlinear Euler equations employing accurate higher order spatial differencing, time stepping techniques and non-reflecting inflow/outflow boundary condition. The time-domain result using the linearised Euler equations shows good agreement with the analytical solution using the modified LINSUB code. Through the comparison of the nonlinear time-domain result using the full nonlinear Euler equations with the linear, it is found that the acoustic mode amplitude of the nonlinear response is less than that of the linear response due to the energy cascade from low frequency components to the high frequency ones. Considering the merits of the time-domain methods over the typical time-linearised frequency-domain analysis, the current method is expected to be promising tools for analyzing the effects of the airfoil shapes, non-uniform background flow, linear-nonliear regimes on the broadband noise due to turbulence-cascade interaction.
An Experimental Study on the Vertical Vibration Transfer in Horizontal Way according to Shear Wall Building Structures due to Exciting Vibration Forces
Chun, Ho-Min ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 270~282
DOI : 10.5050/KSNVN.2006.16.3.270
In general, the vertical vibration problems for strength of members and serviceability of building structures are not considered in structural design process, but the prediction of the vertical vibration is very important and essential to structural design process. This study aims to investigate the characteristics of vertical vibration in terms of the transfer of horizontal directions to near-rooms on the shear wall building structures. In order to examine the characteristics of vertical vibration, the modal test and the impact (heel-drop and hammer) excitation experiments were conducted several times on two building structure. The results from the experiments are analyzed and compared with the results. The results of this study suggest that the characteristics of vertical vibration transfer in horizontal way are effected from the fundamental frequency of the slabs, and are effected the shear wall on the Path of the vibration transfer.
A Study on the Rejection of Dynamic Disturbance Forces in a Magnetically Suspended System Using Flux Feedback
Kim, Jong-Ki ; Lee, Key-Seo ; Lee, Jun-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 283~290
DOI : 10.5050/KSNVN.2006.16.3.283
This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.
Helicopter BVI Noise Prediction Using Acoustic Analogy and High Resolution Airloads of Time Marching Free Wake Method
Chung, K. ; Lee, D.J. ; Hwang, C. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 291~297
DOI : 10.5050/KSNVN.2006.16.3.291
The BVI(blade vortex interaction) noise Prediction has been one of the most challenging acoustic analyses in helicopter aeromechanical Phenomenon. It is well known high resolution airloads data with accurate tip vortex positions are necessary for the accurate prediction of this phenomenon. The truly unsteady time-marching free-wake method, which is able to capture the tip vortices instability in hover and axial flights, is expanded with the rotor flapping motion and trim routine to predict unsteady airloads in forward and descent flights. And Farassat formulation 1-A based on the FW-H equation is applied for the noise prediction considering the blade flapping motion. Main objective of this study is to validate the newly developed prediction code. To achieve the objective, the descent flight condition of AH-1 OLS(operational loads survey) configuration is analyzed using present code. The predicted sectional thrust distribution and sectional airloads time histories show the present scheme is able to capture well the unsteady airloads caused by a parallel BVI. Finally, the predicted noise data, observed in two different positions where are 3.44 times of rotor radius far from the hub center, are quite reasonable agreements with the experimental data compared to the other analysis results.
Active Vibration Control of Structure Using LMI Optimization Design of Robust Saturation Controller
Park, Young-Jin ; Moon, Seok-Jun ; Lim, Chae-Wook ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 298~306
DOI : 10.5050/KSNVN.2006.16.3.298
In our previous paper, we developed a robust saturation controller for the linear time-invariant (LTI) system involving both actuator`s saturation and structured real parameter uncertainties. This controller can only guarantee the closed-loop robust stability of the system in the presence of actuator`s saturation. But we cannot analytically make any comment on control performance of this controller. In this paper, we suggest a method to use linear matrix inequality (LMI) optimization problem which can analytically explain control performance of this robust saturation controller only in nominal system. The availability of design method using LMI optimization problem for this robust saturation controller is verified through a numerical example for the building with an active mass damper (AMD) system.
A Vibration Isolation System Design for a Vibration-sensitive Equipment
Hong, Seok-In ; Kim, Ho-Sang ; Lee, Dae-Hee ; Lee, Kyung-Don ; Jang, Han-Kee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 16, issue 3, 2006, Pages 307~312
DOI : 10.5050/KSNVN.2006.16.3.307
In this study a vibration isolation system with the cradle-type support was designed so as to reduce the transient vibration due to positioning motion of the moving mass on worktable as well as to achieve the desired isolation efficiency on the floor vibration. The design procedure was performed in the two steps. The first step to select appropriate isolators to meet the isolation efficiency, and the second step is to reduce the transient vibration of the worktable by adopting the cradle-type support. After the application of the selected isolators with the cradle-type support to the system it was shown that the required vibration criterion(VC-D) was easily satisfied and that the undesirable transient vibration was reduced remarkably.