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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 12, Issue 12 - Dec 2002
Volume 12, Issue 11 - Nov 2002
Volume 12, Issue 10 - Oct 2002
Volume 12, Issue 9 - Sep 2002
Volume 12, Issue 8 - Aug 2002
Volume 12, Issue 7 - Jul 2002
Volume 12, Issue 6 - Jun 2002
Volume 12, Issue 5 - May 2002
Volume 12, Issue 4 - Apr 2002
Volume 12, Issue 3 - Mar 2002
Volume 12, Issue 2 - Feb 2002
Volume 12, Issue 1 - Jan 2002
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Vibration and Radiated Noise Analysis of Plate Covered with Damping Material
Lee, Chang-Myung ; Lee, Jun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 317~322
DOI : 10.5050/KSNVN.2002.12.5.317
A solution procedure of vibration and radiated noise of the plate covered with damping material has been studied. To predict the vibration level and the radiated noise level of the plate covered with damping material, FEM and BEM have been utilized, respectively. A property of damping material has been measured by using a composite beam. Two different kinds of measuring procedure for the composite beam have been introduced by comparing its characteristics. The numerical prediction of vibration level of the Plate covered with damping material has been proved with experimental data.
Post-buckling of Non-uniform Cantilever Column Subjected to a Combined Load
Shin, Young-Jae ; Masakatsu Chiba ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 323~329
DOI : 10.5050/KSNVN.2002.12.5.323
This paper presents the application of the technique of differential transformation to the post-buckling problem of non-uniform cantilever column subjected to a combined load. Numerical calculations are carried out and compared with previously published results to validate the results of the present method. The results obtained by this method agree very well with those reported in the previous works. The results obtained by the present method are presented for both various non-uniform columns and loads.
Vibration Analysis of a Beam Having n Through-the-width Splits
Hwang, J.K. ; Lee, M.H. ; Shin, Y.J. ; Kim, C.H. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 330~337
DOI : 10.5050/KSNVN.2002.12.5.330
A frequency equation of beam subjected to the axial load and having ηthrough-the-width-splits is developed. The beam comprises of beam elements that are split into the upper and the lower part, and non-split beam elements. Equations of motion of each beam element are non-dimensionalized with respect to length. The frequency equation of beam is derived from that of each beam element, which satisfies the displacement of the longitudinal and transverse vibration and the boundary conditions between the beam elements. Numerical simulation and experimental work for the beam having several split beam elements are carried out to demonstrate the analytical development and its validity. The experimental results are in good agreement with those of the present frequency equation. The relationships between the split beam width and natural frequencies, and also the relationships between number of split and natural frequencies, in case that the total beam split length is same. are discussed.
An Experimental Study on Brake Judder of Braking on Vehicle
Hong, Il-Min ; Lee, Won-Sub ; Lee, Jong-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 338~345
DOI : 10.5050/KSNVN.2002.12.5.338
The study presents a new testing and analysis method for brake judder on vehicle. For the identification of the excitation mechanism of a brake judder, it is necessary to measure the dynamic brake disc geometry during braking on vehicle. The non-contact sensor system was used to monitor the brake disc geometry. Brake torque variation (BTV) caused by disc thickness variation (DTV) is the primary excitation for brake judder. The mechanical effects generating BTV are linked not only to initial manufacturing tolerances but also to uneven wear. Therefore, the brake disc geometry should be strictly managed to initial condition. The aim of this study has been to measure the dynamic DTV and runout on vehicle and analyze the influence of test parameters on brake judder and compare the disc component with vehicle matching about the DTV Profile. As a result of this study, The amplitude of brake judder is proportional to vehicle speed and fluid pressure fluctuation on braking. The major sources of brake judder are directly related to disc thickness variation and side runout variation of corner assembly (disc, hub. bearing).
A Study on the Impulse Waves Discharged from the Exit of the Convergent and Divergent Pipes
Lee, D.H. ; Lee, M.H. ; Kweon, Y.H. ; Kim, H.D. ; Park, J.H. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 346~354
DOI : 10.5050/KSNVN.2002.12.5.346
The present study is to investigate the propagation characteristics of the impulse waves discharged from the exit of the convergent and divergent pipes. An experiment is carried out using a shock tube with an open end and is compared to the computation of the axisymmetric, compressible, unsteady Euler equations, which are solved by the second-order total variation diminishing (TVD) scheme. For the computational work, several initial compression waves are assumed inside the pipe so that those are the same to the experimental ones of the shock tube. The results show that the peak pressures of the impulse waves discharged from the exit of convergent and divergent pipes decrease with an increase in the wavelength of the initial compression wave. All of the impulse waves have a strong directivity toward the pipe axis, regardless of the exit type of the pipe employed. The impulse waves discharged from the divergent pipe are stronger than those from the straight pipe, while the impulse waves of the convergent pipe are weaker than those from the straight pipe. It is found that the convergent pipe can play a role of a passive control to reduce the peak pressure of the impulse wave. The present computations represent the experimented impulse waves with a good accuracy.
Design Improvement via Structural Dynamics Modification - Application to Noise Reduction in Outdoor Unit of Air Conditioner
Choi, Sang-Hyeon ; Park, Nam-Gyu ; Park, Youn-Sik ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 355~364
DOI : 10.5050/KSNVN.2002.12.5.355
The goal of this research is to reduce noise level of an outdoor unit of air conditioner by changing its dynamic characteristics using SDM (structural dynamics modification) technique. At first, the emitting noise was measured and analyzed. The measurement records show the most critical frequency components which influences on the noise level. Then it was tried to move the natural frequencies outside the critical frequency region by SDM. Since it is very difficult to get a reliable FE model of air conditioner, experimentally measured frequency response functions were used to derive sensitivities that are very important to obtain design changes. The positions of modification and the thickness of modifying structures were determined to improve the dynamic characteristics of air conditioner. The recommended design guideline to move its natural frequencies outside the targeting frequency range was obtained. Then in order to prove its effectiveness, the changed design was experimentally tested and found that the SDM result is very effective to reduce not only its vibration but also its emitting noise.
Vibration Control of Flexible Rotor Systems Using an Electro-rheological Fluid Damper
Lim, Seung-Chul ; Chae, Jeong-Jae ; Park, Sang-Min ; Yun, Eun-Gyu ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 365~373
DOI : 10.5050/KSNVN.2002.12.5.365
This paper concerns the design and application of an electro-rheological (ER) fluid damper to semiactive vibration control of rotor systems. In particular, the system under present study is constructed structurally flexible in order to explore multiple critical speeds within operation range. To this end, the dynamic models of the proposed ER damper and its associated amplifier are derived in the first place. Subsequently entire rotor system model is assembled along with the dynamics of the end effector based on a finite element method enabling prediction as to its free and forced vibration characteristics. Next, an artificial intelligent (AI) feedback controller is synthesized taking into account the peculiarity of Coulomb damping effect in rotor applications. Finally, computational and experimental results are presented including model validation and control performances. In practice, such an AI control proved effective whether the spin speed was either before or after critical speeds.
New Active Muffler System Utilizing Destructive Interference by Difference of Transmission Paths
Hwang, Yo-Ha ; Lee, Jong-Min ; Kim, Seung-Jong ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 374~379
DOI : 10.5050/KSNVN.2002.12.5.374
A new active muffler system has been developed and its superior performance on both noise reduction and engine torque increase is demonstrated with experiment. Main characteristic of the proposed muffler system is the use of destructive interference by transmission path difference of divided exhaust pipes to reduce major exhaust noise components thereby overcoming problems of other active exhaust noise control methods. The exhaust pipe is divided into two sections and joined again downstream. One divided pipe has a sliding mechanism to vary its length, which is controlled to make half wavelength transmission path difference for the major engine rpm frequency. In this system one divided pipe is used to control major rpm frequency and its Harmonics and another pipe is used to control noise component double the frequency of rpm. An after-market tuning muffler, which has very simple internal structure and minimal back pressure, is also installed to remove remaining wideband noise. To make the system to be small enough to be practical, conventional muffler is also installed and used in low rpm range and active muffler is only employed in high rpm range. Noise reduction of the proposed system is comparable to conventional passive muffler. The engine dynamo test has proved the proposed system can recover almost all the torque lost by conventional muffler.
Optimal Design for Steam-turbine Rotor-bearing System Using Combined Genetic Algorithm
Kim, Young-Chan ; Choi, Seong-Pil ; Yang, Bo-Suk ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 380~388
DOI : 10.5050/KSNVN.2002.12.5.380
This paper describes the optimum design for low-pressure steam turbine rotor of 1,000 MW nuclear power plant by using a combined genetic algorithm, which uses both a genetic algorithm and a local concentrate search algorithm (e.g. simplex method). This algorithm is not only faster than the standard genetic algorithm but also supplies a more accurate solution. In addition, this algorithm can find the global and local optimum solutions. The objective is to minimize the resonance response (Q factor) and total weight of the shaft, and to separate the critical speeds as far from the operating speed as possible. These factors play very important roles in designing a rotor-bearing system under the dynamic behavior constraint. In the present work, the shaft diameter, the bearing length, and clearance are used as the design variables. The results show that the proposed algorithm can improve the Q factor and reduce the weight of the shaft and the 1st critical speed.
Investigation of Dynamic Absorbing System in the Gas-operated Gun with High Transmitted Shock Force
Kim, Hyo-Jun ; Park, Young-Pil ; Yang, Hyun-Seok ; Choe, Eui-Jung ; Lee, Sung-Bae ; Hong, Kye-Jung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 12, issue 5, 2002, Pages 389~396
DOI : 10.5050/KSNVN.2002.12.5.389
In this study, the dynamic absorbing system for gas operated gun has been investigated. For this purpose, firstly. mathematical model of gas-operated shoulder-fired gun has been constructed. Through a series of experimental works using the devised test setup, the characteristic behavior of mathematical model was compared to the test results. In order to design the dynamic absorbing system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. In order to implement the more efficient dynamic absorbing system, the characteristic performance of stroke-dependent variable damping system has been analyzed with some opening area curves. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation and experiment using the previous test apparatus.