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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
Selecting the target year
Determination of Shock Response Spectrum Using FRF of Statistical Energy Analysis Method
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 551~560
DOI : 10.5050/KSNVN.2004.14.7.551
A method how to determine the shock response spectrum from the FRF of the statistical energy analysis( SEA ) is presented here. The system of 3 different Plates connected by bolt joints is selected simulating missile structural sections Joined together. First, the SEA model was rendered by SEA parameters which were determined from experimental SEA method. Then, the mobility power was input to the SEA model and we can verify the validity of the model in the medium to high frequency range checking the reproduction of output average velocity. And, the shock induced shock response spectrum(SRS) was obtained using SEA FRF and arbitrarily chosen experimental FRF. We have compared the thus obtained SRS with actually measured SRS and they were relatively in good agreement. In this paper, we used the measured SEA FRF and therefore we have got the SRS well agreed with actually measured SHS even in the low frequency range. If the SEA FRF of well verified SEA model is used, the good result will come out in SEA effective frequency range which is more important at SRS.
Nonlinear Dynamic Charateristics of Constrained Cantilever Tube with Attached Mass
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 561~568
DOI : 10.5050/KSNVN.2004.14.7.561
The nonlinear dynamic characteristic of a straight tube conveying fluid with constraints and an attached mass on the tube is examined in this study An experimental apparatus with an elastomer tube conveying water which has an attached mass and constraints is made and comparisons are made between the theoretical results from the non-linear equation of motion of piping system and the experimental results. The comparisons show that the tube is destabilized as the magnitude of the attached mass increases, and stabilized as the position of the attached mass closes to the fixed end. In case of a small end-mass, the system shows complicated and different types of solutions. For a constant end-mass. the system undergoes a series of bifurcations after the first Hopf bifurcation, as the flow velocity increases. which causes chaotic motions of the tube eventually.
Detection of External Sound Frequency by Using the Distributed Fiber Optic Sensor Net
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 569~576
DOI : 10.5050/KSNVN.2004.14.7.569
In this paper, to detect external sound frequencies on the latticed structure, fiber optic sensor net using Sagnac interferometer was fabricated and tested. The latticed structure was fabricated with a dimension of 50 cm in width and 50 cm in height. The optical fiber of 50m in length was distributed and fixed on the surface of the latticed structure. Single mode fiber, a laser with 1,550 nm in wavelength, 2
2 coupler were used. External sound signal, 240 Hz, 495 Hz, 1.445 kHz, 2k Hz, applied to the fiber optic sensor net and the detected optical signals were compared to the detected microphone signals against time and frequency domains. Based on the experimental results, fiber optic sensor net using Sagnac interferometer detected external sound frequency, effectively. This system can be expanded to the structural health monitoring system.
Damping Patch Placement on Outdoor Unit of Air-conditioner by Using Structural Intensity Technique
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 577~585
DOI : 10.5050/KSNVN.2004.14.7.577
In this paper, reactive shearing structural intensity method is extended to damping patches placement on outer panels of outdoor unit of air-conditioner to reduce its structural borne noise. The structural intensity is calculated from the normal velocities of structures that are measured by using a laser scanning vibrometer, and
-space (wave-number domain) signal processing is used to obtain the spatial derivatives in formulation of structural intensity. This method is applied to the outdoor unit of air-conditioner on shaker-exciting mode and operating mode. and then damping patches are placed over area of high reactive shearing structural intensity for reducing the radiated noise. Experimental results show the largest reduction of sound pressure level of an outdoor unit by appling small damping patches to optimal position.
Can We Hear the Shape of a Noise Source\ulcorner
Kim, Yang-Hann ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 586~603
DOI : 10.5050/KSNVN.2004.14.7.586
One of the subtle problems that make noise control difficult for engineers is “the invisibility of noise or sound.” The visual image of noise often helps to determine an appropriate means for noise control. There have been many attempts to fulfill this rather challenging objective. Theoretical or numerical means to visualize the sound field have been attempted and as a result, a great deal of progress has been accomplished, for example in the field of visualization of turbulent noise. However, most of the numerical methods are not quite ready to be applied practically to noise control issues. In the meantime, fast progress has made it possible instrumentally by using multiple microphones and fast signal processing systems, although these systems are not perfect but are useful. The state of the art system is recently available but still has many problematic issues : for example, how we can implement the visualized noise field. The constructed noise or sound picture always consists of bias and random errors, and consequently it is often difficult to determine the origin of the noise and the spatial shape of noise, as highlighted in the title. The first part of this paper introduces a brief history, which is associated with “sound visualization,” from Leonardo da Vinci's famous drawing on vortex street (Fig. 1) to modern acoustic holography and what has been accomplished by a line or surface array. The second part introduces the difficulties and the recent studies. These include de-Dopplerization and do-reverberation methods. The former is essential for visualizing a moving noise source, such as cars or trains. The latter relates to what produces noise in a room or closed space. Another mar issue associated this sound/noise visualization is whether or not Ive can distinguish mutual dependence of noise in space : for example, we are asked to answer the question, “Can we see two birds singing or one bird with two beaks\ulcorner”
A Parameter Study on the Frequency Characteristics of the Structural-acoustic Coupled System
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 604~611
DOI : 10.5050/KSNVN.2004.14.7.604
It is well known that wall impedance essentially determines how sound wave transmits from one place to another. The wall impedance is related with its dynamic properties : for example, the mass, stiffness, and damping characteristics. It is noteworthy, however, that the wall impedance is also function of spatial characteristics of two spaces that is separated by the wall. This is often referred that the wall is not locally reacting. In this paper, we have attempted to see how the acoustic characteristics of the two spaces is affected by various structure parameters such as density, applied tension, and a normalized length of the wall. Calculations are conducted for two different modally reacting boundary conditions by modal expansion method. The variation of the Helmholtz mode and the structural-dominated mode are analyzed as the structure parameters vary. The displacement distribution of the structure, pressure and active intensity of the inside and outside cavity are presented at the Helmholtz mode and the structure-dominated mode. It is shown that the frequency characteristics are governed by both structure-and fluid-dominated mode. The results exhibit that the density of the structure is the most sensitive design parameter on the frequency characteristics for the coupling system as we could imagine in the beginning. The Helmholtz mode frequency decrease as density increases. However. it increases as applied tension and an opening size increase. The bandwidth of the Helmholtz mode is mainly affected by density of the structure and its opening size.
Development of a Robust Controller for Piezo/beam Systems
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 612~618
DOI : 10.5050/KSNVN.2004.14.7.612
This paper presents a robust vibration control methodology for smart structural systems. The governing equation and associated boundary conditions of the smart structural system are derived by using Hamilton's principle. The assumed mode method is used to discretize the governing equation into a set of ordinary differential equation. A robust controller is designed using a linear matrix inequality (LMI) approach for the multiobjective synthesis. The design objectives are to achieve a mix of H
performance and H
performance satisfying constraints on the closed-loop pole locations in the presence of model uncertainties. Numerical examples are presented to demonstrate the effectiveness of LMI approach in damping out the multiple vibration modes of the piezo/beam system.
Active Vibration Control of a Beam Using Direct Velocity Feedback
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 619~625
DOI : 10.5050/KSNVN.2004.14.7.619
Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair. because the sensor-actuator pair has strictly positive real (SPR) property In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a Point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB show robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a “skyhook” damper, hut the point sensor-distributed actuator pair with DVFB acts as a “skyhook” rotational damper pair.
A Study on the Proper Vocabularies for Evaluating Floor Impact Sound in Apartment Houses Considering Rating Methods
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 626~631
DOI : 10.5050/KSNVN.2004.14.7.626
In this study, the extracted words from the former study such as annoying, loud, noisy, irritating, disagreeable, strident, disturbed, and dissonant are given to subjects in psycho acoustic experiment lab. And then, correlation analysis between the words and floor impact noise rating method were carried out. As a result of this study followings are suggested ‘Annoying’ is the word most accurately expressing the subjects’ unpleasant feeling of domestic floor impact noise. The results of this study could be basic materials for psycho acoustic experiments for criteria on floor impact noise and Sound Classification on Floor Impact Sound Insulation Performance.
The Characteristics of Blasting Vibration in the Construction of Apartment and Buildings in Urban Area
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 632~638
DOI : 10.5050/KSNVN.2004.14.7.632
In order to evaluate the effect of blasting vibration in buildings and it's resident located around blasting construction field in urban area, blasting vibration characteristics were measured by the vibration level, vibration velocity. The 250g and 750g of charged powder were used at the apartment and at the ground, respectively. In the measurement of the ground, 2 (perpendicularity) axis was the highest value in vibration level, but vertical direction was the highest value at 25 m point and longitudinal direction was the highest value at 50 m point in vibration velocity. The amount of measurement was high value when measuring point is higher than blasting source, while that of measurement was low value when measuring point is lower than blasting source. In the measurement of the apartment, Z axis was the highest value in vibration level, but in vibration velocity transverse direction was the highest value at ground, was vertical direction at 1st floor, was longitudinal direction at 3rd floor and was vertical and longitudinal direction at 5th floor. The vibration level and the vibration velocity of 50 m point showed higher correlation value than 25 m point at the ground, but those of 25 m point showed higher correlation value than 50 m point at the apartment.
Vibration Analysis of Composite-VEM Thin-walled Rotating Beam Using GHM Methodology
Transactions of the Korean Society for Noise and Vibration Engineering, volume 14, issue 7, 2004, Pages 639~647
DOI : 10.5050/KSNVN.2004.14.7.639
This paper concerns the analytical modeling and dynamic analysis of advanced rotating blade structure implemented by a dual approach based on structural tailoring and viscoelastic material technology. Whereas structural tailoring uses the directionality properties of advanced composite materials, the passive material technology exploits the damping capabilities of viscoelastic material (VEM) embedded into the host structure. The main structure is modeled as a composite thin-walled beam Incorporating a number of nonclassical features such as transverse shear. anisotropy of constituent materials, and rotary inertia etc. The VEM layer damping treatment is modeled by using the Golla-Hughes-McTavish (GHM) method, which is employed to account for the frequency-dependent characteristics of the VEM. The displayed numerical results provide a comprehensive picture of the synergistic implications of both techniques, namely, the tailoring and damping technology on dynamic response of a thin-walled beam structure exposed to external time-dependent excitation.