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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 24, Issue 12 - Dec 2014
Volume 24, Issue 11 - Nov 2014
Volume 24, Issue 10 - Oct 2014
Volume 24, Issue 9 - Sep 2014
Volume 24, Issue 8 - Aug 2014
Volume 24, Issue 7 - Jul 2014
Volume 24, Issue 6 - Jun 2014
Volume 24, Issue 5 - May 2014
Volume 24, Issue 4 - Apr 2014
Volume 24, Issue 3 - Mar 2014
Volume 24, Issue 2 - Feb 2014
Volume 24, Issue 1 - Jan 2014
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Vibration and Stability Analysis of a Multi-stepped Shaft System of Turbo Compressor
Seo, Jung-Seok ; Kang, Sung-Hwan ; Park, Sang-Yoon ; An, Chang-Gi ; Song, Ohseop ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 583~591
DOI : 10.5050/KSNVE.2014.24.8.583
The mathematical modeling on the free vibration and stability of a multi-stepped shaft of turbo compressor is performed in this study. The multi-stepped shaft is modeled as a non-uniform Timoshenko beam supported by anisotropic bearings. It is assumed that the shaft is spinning with constant speed about its longitudinal axis and subjected to a conservative axial force induced by front and rear impellers attached to the shaft. The structural model incorporates non-classical features such as transverse shear and rotary inertia. A structural coupling between vertical and lateral motions is induced by Coriolis acceleration terms. The governing equations are derived via Hamilton`s variational principle and the equations are transformed to the standard form of an eigenvalue problem. The implications of combined gyroscopic effect, conservative axial force, bearing stiffness and damping are revealed and a number of pertinent conclusions are outlined. In this study analytical results are compared with those from ANSYS finite element analysis and experimental modal testing.
Driveline Vibration Reduction of FR(front engine rear wheel drive) Vehicle at Rapid Acceleration
Kim, Yong-Dae ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 592~599
DOI : 10.5050/KSNVE.2014.24.8.592
A torsional vibration at driveline happens seriously at rapid vehicle acceleration. The torsional vibration at driveline can be reduced by optimization of joint angle and yoke phase angle of driveline. But, the joint angle of driveline is changed according to vehicle driving condition as acceleration, deceleration, forward and backward driving, so that excessive vibration is transmitted to vehicle body at specific driving condition. Especially under rapid acceleration condition, vibration transmitted to body could be maximized because excitation force at rapid acceleration is bigger than that at normal driving condition due to changed joint angle. The torsional vibration of driveline can be kept at low level by controlling suspension parameter to minimize rigid axle displacement as well as optimizing joint angles considering the vehicle acceleration condition.
Muffler Design Using Transmission Loss Prediction Considering Heat and Flow
Kim, Hyunsu ; Kang, Sang-Kyu ; Lim, Yun-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 600~605
DOI : 10.5050/KSNVE.2014.24.8.600
Two mufflers for a large-size sedan are suggested aiming (1) sporty-sound and (2) quiet-sound as well as both satisfying low back-pressure and low manufacturing cost. Transmission loss prediction considering heat and flow may increase the accuracy and reduce the development cost in muffler design; thus, GT-power prediction considering heat, flow, and acoustics is utilized. By understanding the fundamentals of flow-acoustic theory in small orifice(hole), an effective muffler design concept is proposed. Vehicle tests show the consistence with predictions for sound; also a back-pressure test bench confirms the advantage in pressure drop for both suggested mufflers. Those suggested mufflers also have advantages in manufacturing cost due to simplicity of the design.
Development of FE-SEA Hybrid Model for the Prediction of Vehicle Structure-borne Noise at Mid-frequencies
Yoo, Ji Woo ; Chae, Ki-Sang ; Charpentier, A. ; Lim, Jong Yun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 606~612
DOI : 10.5050/KSNVE.2014.24.8.606
Vehicle simulation models for noise and vibration prediction have been developed so far generally in two schemes. One is FE models generally used for problems below 200 Hz such as booming noise, and the other is SEA models for high frequencies of more than 1 kHz, representatively related to sound packages. There have been many researches to develop a simulation model for 200~1000 Hz, so-called mid-frequency region, and this paper shows one practical result that covers the trimmed body of a sedan vehicle. The simulation model is developed based on an FE model, and then FE elements at some areas are substituted with SEA elements to reduce DOFs. SEA panels are described by modal density, radiation efficiency, stiffness and damping characteristics that are found from some numerical assessments. Sound packages are modeled similarly as a conventional SEA model. The results obtained from the hybrid model were compared to experimental results. Predicted pressure and vibrational velocity generally show a good agreement. The developed simulation model and related technology are successfully being used in vehicle development process.
Securing Reliability Analysis of Humidifier Fuel Cell
Ha, Jeong-Min ; Lee, Jong-Myeong ; Jang, Yong-Ho ; Kim, Seon-Hwa ; Choi, Byeong-Keun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 613~620
DOI : 10.5050/KSNVE.2014.24.8.613
A few Humidifier have vibration problems caused by velocity of flow, piping vibration and karman vortex. The crack is generated on pipe wall and humidifier are damaged. Vibration analysis is conducted to prevent pipe damage during the design. But the other problem are caused after analysis of vibration. Therefore in this paper, the vibration and static analysis have been measured and analyzed for pipes and curve. Also modal test is conducted for analysis of natural frequency.
Numerical Investigation on Motion of the Scale Model of a Floating Wind Turbine Using Multilayer TLDs
Ha, Minho ; Cheong, Cheolung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 621~627
DOI : 10.5050/KSNVE.2014.24.8.621
In this paper, a possibility of controlling the motion of a floating wind turbine with the tuned liquid damper(TLD) is numerically investigated. First, motion of the scale model of a floating wind turbine without the TLD is predicted and its results are compared to the measured data. There are reasonably good agreements between two results, which confirms validity of the present numerical methods. Then, the effect of TLD is quantitatively assessed by comparing the prediction results for the floating wind turbine with and without the TLD. It is shown that the motion of the scale model derived by external forces can be reduced by using the TLD. On a basis of this result, a multi-layer TLD is proposed to generate larger reaction force of the TLD at the fixed target frequency. The motions of the scale model with the multi-layer TLDs are computed and compared with that of the single-layer TLD. It is shown that the multi-layer TLD generate stronger reaction force and thus more reduce the motion of the floating body than the single-layer TLD.
Analysis of Sources and Contribution for the Radiated Noise of Drum-type Washing Machine
Kim, Ji Man ; Jung, Byung Kyoo ; Heo, So Jung ; Ahn, Se Jin ; Jeong, Weui Bong ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 628~635
DOI : 10.5050/KSNVE.2014.24.8.628
The procedure to estimate the sources of noise and vibrations in a typical drum-type washing machine was presented. The sources should be identified to predict the radiated noise with computational model of structure. Source identification techniques based on singular decomposition were implemented using the measured signals of accelerometers and microphones. The finite element analysis and indirect boundary element analysis were implemented to predict the structural vibrations and the acoustic pressures at the field points. The predicted results by only structural sources were compared with those by both structural and acoustical sources. It was verified that not only the structural-borne source but also air-borne source should be considered to predict the radiated noise with better accuracy. The contribution analysis with respect to the transfer path was also preformed.
Characterization of Pipe Defects in Torsional Guided Waves Using Chirplet Transform
Kim, Chung-Youb ; Park, Kyung-Jo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 636~642
DOI : 10.5050/KSNVE.2014.24.8.636
The sensor configuration of the magnetostrictive guided wave system can be described as a single continuous transducing element which makes it difficult to separate the individual modes from the reflected signal. In this work we develop the mode decomposition technique employing chirplet transform, which is able to separate the individual modes from dispersive and multimodal waveform measured with the magnetostrictive sensor, and to estimate the time-frequency centers and individual energies of the reflection, which would be used to locate and characterize defects. The reflection coefficients are calculated using the modal energies of the separated mode. Results from experimental results on a carbon steel pipe are presented, which show that the accurate and quantitative defect characterization could become enabled using the proposed technique.
Experimental Investigation to Establish Correlation between Specific Film Thickness and Sound Signals in a Spur Gear System
Kim, Jongsik ; Amarnath, M. ; Lee, Sangkwon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 643~650
DOI : 10.5050/KSNVE.2014.24.8.643
Gear transmission system is widely applied in engineering. As the problem of contact fatigue, wear, lubrication failure etc, the condition of gear teeth contacts will be worse. The vibration and sound signals in the gear system will be affected by the some failures like scuffing, abrasive wear and spalling due to the deterioration of gear teeth surface. By studying the estimation of specific film thickness, measurement of reduction in tooth thickness, visual examination of wear mechanisms on the gear teeth and their effects on the statistical parameters of vibration and sound signals, the research obtained the satisfactory results on accessing the surface fatigue wear in a spur gear system. The paper utilizes the relationship between statistical parameters obtained from sound signals and Stribeck curve to confirm the hypothesis of dependency of surface fatigue wear, specific film thickness.
Comparison of Impact Sound Insulation Performances of Apartment Floors Against Heavy-weight Impact Sources via Field Measurement Data
Yun, Chang-Yeon ; Yeon, Jun-Oh ; Kim, Myung-Jun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 24, issue 8, 2014, Pages 651~658
DOI : 10.5050/KSNVE.2014.24.8.651
Notification 2013-611 of MOLIT has come into effect. It relates primarily to new standard impact source. In this study, an in-depth experimental analysis of the difference between a bang machine and an impact ball was performed via field testing of shear wall and flat plate structure at 51 sites. This paper focuses on the difference in single number quantities between a bang machine and an impact ball. At wall thicknesses of 180 and 210 mm in shear wall structure, the single number quantities exhibited differences of 3.1 and 4.5 dB, respectively, and at thicknesses exceeding 250 mm in flat plate structure, the difference was constant at 4.6 dB. With regard to flat plate structures, the single-index difference increased up to 11 dB as the thickness of the floor slab increased. In general, the highest level of contribution for the bang machine was 63 Hz, irrespective of thickness determining bandwidth. The highest level for the impact ball were 63 Hz and 125 Hz. In future research, when reviewing additional field performance measurement data, it will be necessary to consider a detailed examination instead of the current method of uniformly adding 3 dB for all thicknesses and types of structures.