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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 15, Issue 12 - Dec 2005
Volume 15, Issue 11 - Nov 2005
Volume 15, Issue 10 - Oct 2005
Volume 15, Issue 9 - Sep 2005
Volume 15, Issue 8 - Aug 2005
Volume 15, Issue 7 - Jul 2005
Volume 15, Issue 6 - Jun 2005
Volume 15, Issue 5 - May 2005
Volume 15, Issue 4 - Apr 2005
Volume 15, Issue 3 - Mar 2005
Volume 15, Issue 2 - Feb 2005
Volume 15, Issue 1 - Jan 2005
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Measurements of Whole-body Vibration Exposed from and Their UH60-helicopter Analysis Results
Cheung, Wan-Sup ; Byeon, Joo-Hyun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1327~1331
DOI : 10.5050/KSNVN.2005.15.12.1327
This Paper addresses what amount of whole-body vibration is exposed to Korean pilots of UH60 helicopters during their mission flight. To measure the expose4 whole-body vibration, the 12-axis whole-body vibration measurement system was used. It enables the direct measurement of whole-body vibration exposed from the body contact area consisting of the feet, hip and back. The measured 12-axis vibration signals were used to evaluate the vibration comfort level experienced by the pilots of UH60 helicopters. The evaluated vibration comfort level is found to be closeto 0.74-0.79m/s, which is equivalent to the semantic scale of `fairly uncomfortable`. To assess the health effects of whole-body vibration exposed to Korean pilots of UH60 helicopters during their mission flight, the rms-based and VDV(vibration dose value)-based evaluation schemes, recommended by ISO 2631-1:1977, were exploited in this work. The evaluated results indicate that Korean pilots cannot avoid the fatigue-decreased proficiency limit after two-hour continuous flight. The whole-body vibration level exposed from the UH60 helicopters during continuous 10-hours mission flight is found to reach to the vibration exposure limit.
Dynamic Analysis of Vehicle Sub-frame
Lee, B.H. ; Kim, C.J. ; Kim, G.H. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1332~1339
DOI : 10.5050/KSNVN.2005.15.12.1332
The vibration of Powertrain are one of the import design characteristics of a vehicle. Powertrain is mostly mounted to the front subframe and powertrain mounting has an important role in determining the vehicle vibration characteristics. In this paper, the accuracy of the vibration analysis for the front subframe is discussed. The dynamic characteristic of subframe are measured from vehicle test and the finite element model updating are performed that natural frequency, mass and MAC of the experimental and theoretical modal analysis are compared. The subframe mounting stiffness are obtained the iteration method based on the vibration of subframe from vehicle test. Finally, the result of dynamic analysis which is operated dynamic load is compared with experimental one of vehicle test.
Seismic Responses of Isolated Bridges Considering the Relative Stiffness Ratio
Seo, Hyun-Woo ; Kim, Nam-Sik ; Cheung, Jin-Hwan ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1340~1346
DOI : 10.5050/KSNVN.2005.15.12.1340
In this study, based on shaking table test results on a seismically isolated bridge model, an inelastic numerical model is refined by using Bouc-Wen model representing the hysteretic behavior of isolators. Seismic responses of isolated bridges are numerically investigated varying with relative stiffness ratio(RSR), which is a ratio of the effective stiffness of isolator to the lateral stiffness of bridge pier, From the results, it is found that an adequate range of relative stiffness ratio could be defined for seismic design of isolated bridges without considering the flexibility of piers.
Free Vibration Analysis of Al Cantilever Square Plates with a Brass Inclusion
Lee, Youn-bok ; Lee, Young-shin ; Lee, Se-hoon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1347~1354
DOI : 10.5050/KSNVN.2005.15.12.1347
The free vibration characteristics of Al cantilever square plates with a brass inclusion were analyzed experimentally and numerically The experimentally obtained natural frequencies and mode shapes were compared with the FEM analysis results. The impulse exciting method was used for experiment and ANSYS software package was used for FEM analysis. The natural frequencies obtained iron experiment and numerical analysis matched within
. It was found that the natural frequencies of the Al cantilever square plates with a brass inclusion decrease as the size of inclusion increases. For the third mode shape, comparing the nodal line of the Al plate and the Al plate with a inclusion, the mode shape showed the reversed quadratic curve. The natural frequencies of inclusion plate were decreased as the location of inclusion moves from the clamped edge to the tree edge.
The Effects of the Stiffness Mistuning on the Dynamic Response of Periodic Structures under a Harmonic Force
Ahn, T.K. ; Shkel A.M. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1355~1360
DOI : 10.5050/KSNVN.2005.15.12.1355
Periodic structures can be applied as a MEMS(micro-electro-mechanical system) sensor or actuator due to low energy loss and wideband frequency response. The dynamic behavior of a mistuned periodic structure Is dramatically changed from that of a perfectly tuned periodic structure. The effects of mistuning, coupling stiffness, and driving point on the forced vibration responses of a simple periodic structure ate investigate4 through numerical simulations. On the basis of that, one can design effective and reliable MEMS components using periodic structures.
Vibration Analyses of Cylindrical Hybrid Panel with Viscoelastic Layer Based on Layerwise Finite Elements
Oh, Il-Kwon ; Cheng, Tai-Hong ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1361~1369
DOI : 10.5050/KSNVN.2005.15.12.1361
Based on a full layerwise displacement shell theory, the nitration and damping characteristics of cylindrical sandwiched panels with viscoelastic layers are investigated. The transverse shear deformation and the normal strain of the cylindrical hybrid panels are fully taken into account for the structural damping modelling. The present finite element model Is formulated by using Hamilton`s virtual work principle and the cylindrical curvature of hybrid panels is exactly modeled. Modal loss factors and frequency response functions are analyzed for various structural parameters of cylindrical sandwich panels. Present results show that the full layerwise finite element method can accurately predict the vibration and damping characteristics of the cylindrical hybrid panels with surface damping treatments and constrained layer damping.
Pressure Drop and Vibration Characteristics of the Capsule with the Modification of Bottom Structures
Choi, M.H. ; Choo, K.N. ; Cho, M.S. ; Kim, B.G. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1370~1377
DOI : 10.5050/KSNVN.2005.15.12.1370
The bottom structure of an instrumented capsule is a part which is joined at the receptacle of the flow tube in the reactor in-core. A geometrical change of the bottom structure has an effect on the pressure drop and the vibration of the capsule. The out-pile test to evaluate the structural integrity of the material capsule called 04M-17U was performed by using a single channel and a half core test loop. From the pressure drop test, the optimized diameter of the cone shape`s bottom structure which satisfies HANARO`s flow requirement (19.6 kg/s) is 71 mm. The maximum displacement of the capsule measured at the half core test loop is lower than 1.0 mm. From the analysis results, it is found that the test hole will not be interfered with near the flow tubes because its displacement due to the cooling water is very small at 0.072 mm. The fundamental frequency of the capsule under water is 9.64 Hz. It is expected that the resonance between the capsule and the fluid flow due to the cooling water in HANARO`s in-core will not occur. Also, the new bottom structure of a solid cone shape with 71 mm in diameter will be applicable to the material and special capsules in the future.
Spatial Manipulation of Sound Using Multiple Sources
Choi, Joung-Woo ; Kim, Yang-Hann ; Park, Young-Jin ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1378~1388
DOI : 10.5050/KSNVN.2005.15.12.1378
Spatial control of sound is essential to deliver better sound to the listener`s position in space. As it can be experienced in many listening environments. the quality of sound can not be manifested over every Position in a hall. This motivates us to control sound in a region we select. The primary focus of the developed method has to do with the brightness and contrast of acoustic image in space. In particular, the acoustic brightness control seeks a way to increase loudness of sound over a chosen area, and the contrast control aims to enhance loudness difference between two neighboring regions. This enables us to make two different kinds of zone - the zone of quiet and the zone of loud sound - at the same time. The other perspective of this study is on the direction of sound. It is shown that we can control the direction of perceived sound source by focusing acoustic energy in wavenumber domain. To begin with, the proposed approaches are formulated for pure-tone case. Then the control methods are extended to a more general case, where the excitation signal has broadband spectrum. In order to control the broadband signal in time domain, an inverse filter design problem is defined and solved in frequency domain. Numerical and experimental results obtained in various conditions certainly validate that the acoustic brightness, acoustic contrast, direction of wave front can be manipulated for some finite region in space and time.
Assessment of Blast-induced Vibration Using Dynamic Distinct Element Analysis
Park, Byung-Ki ; Jeon, Seokwon ; Park, Gwang-Jun ; Do, Deog-Soo ; Kim, Tae-Hoon ; Jung, Du-Seop ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1389~1397
DOI : 10.5050/KSNVN.2005.15.12.1389
Since blast-induced vibration may cause serious problem to the rock mass as well as the nearby structures, the prediction of blast-induced nitration and the stability evaluation must be performed before blasting activities. Dynamic analysis has been increased recently in order to analyze the effect of the blast-Induced vibration. Most of the previous studies, however, were based on the continuum analysis unable to consider rock joints which significantly affect the wave propagation and attenuation characteristics. They also adopted pressure corves estimated tv theoretical or empirical equations as input detonation load, thus there were very difficult to reflect the characteristics of propagating media. In this study, therefore, we suggested a dynamic distinct element analysis technique which uses velocity waveform obtained from a test blast as an input detonation load. A distinct element program, UDEC was used to consider the effect of rock joints. In order to verify the validity of proposed method, the test blast was simulated. The predicted results from the proposed method showed a good agreement with the measured vibration data from the test blast. Through the dynamic numerical modelling on the planned road tunnel and slope, we evaluated the effect of blast-induced nitration and the stability of rock slope.
Free Vibration Analysis of Rectangular Plate with a Rectangular Cutout by Independent Coordinate Coupling Method
Kwak, Moon K. ; Han, Sangbo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1398~1407
DOI : 10.5050/KSNVN.2005.15.12.1398
This paper is concerned with the vibration analysis of a rectangular plate with a rectangular hole. Even though there have been many methods developed for the addressed problem, they suffer from computational time. In this paper, we developed a new methodology called Independent Coordinate Coupling Method which can couple two independent coordinate systems for the entire plate domain and the hole. By matching the deflection condition imposed on the expressions, the relationship between the global axes and the local axes is derived. This formula is then used for the calculation of the eigenvalue problem. The numerical results show the efficacy of the proposed method.
Active Vibration Control of Smart Hull Structure Using MFC Actuators
Sohn, Jung-Woo ; Kim, Heung-Soo ; Choi, Seung-Bok ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1408~1415
DOI : 10.5050/KSNVN.2005.15.12.1408
Active vibration control of smart hull structure using Macro Fiber Composite (MFC) actuator is performed. Finite element modeling is used to obtain governing equations of motion and boundary effects of end-capped smart hull structure. Equivalent interdigitated electrode model is developed to obtain piezoelectric couplings of MFC actuator. Modal analysis is conducted to investigate the dynamic characteristics of the hull structure, and compared to the results of experimental investigation. MFC actuators are attached where the maximum control performance can be obtained. Active controller based on Linear Quadratic Gaussian (LQG) theory is designed to suppress vibration of smart hull structure. It is observed that closed loop damping can be improved with suitable weighting factors in the developed LQG controller and structural vibration is controlled effectively.
Vibration Characteristics Analysis of a Piezoelectric Disc or Torsional Transducers
Lee, Jung-Hyun ; Kim, Jin-Oh ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 15, issue 12, 2005, Pages 1416~1421
DOI : 10.5050/KSNVN.2005.15.12.1416
This paper presents an analytical approach for the vibration characteristics of a piezoelectric disc for torsional vibration transducers. The characteristic equation of the piezoelectric annular disc has been derived from Gibbs` free energy equations and mechanical and electrical equilibrium. With an anisotropic material properties of the disc, the characteristic equation has yielded resonance frequencies. Numerically-calculated results have been compared with the results obtained by the finite element analysis and experiments and have confirmed the validity of the theoretical analysis.