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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
Journal Basic Information
Journal DOI :
The Korean Society for Noise and Vibration Engineering
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Volume & Issues
Volume 18, Issue 12 - Dec 2008
Volume 18, Issue 11 - Nov 2008
Volume 18, Issue 10 - Oct 2008
Volume 18, Issue 9 - Sep 2008
Volume 18, Issue 8 - Aug 2008
Volume 18, Issue 7 - Jul 2008
Volume 18, Issue 6 - Jun 2008
Volume 18, Issue 5 - May 2008
Volume 18, Issue 4 - Apr 2008
Volume 18, Issue 3 - Mar 2008
Volume 18, Issue 2 - Feb 2008
Volume 18, Issue 1 - Jan 2008
Selecting the target year
Estimation of Sensitivity Axis Offset of an Accelerometer for Accurate Measurement of the 6 DOF Human Head Motion
Lee, Jeung-Hoon ; Kim, Kwang-Joon ; Jang, Han-Kee ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 905~912
DOI : 10.5050/KSNVN.2008.18.9.905
Notion sickness is well known to be caused by long time exposure to the very low frequency motion in the multiple axes of human body Since the vestibular system for the perception of low frequency motion is located in the head, accurate measurement of 6 degree of freedom head motion is of great importance. In this study, the measurement system consisting of a safety helmet and 9 translational accelerometers was constructed for the estimation of 3 translational and 3 rotational motions of human head. Since estimation errors of 3 rotational components can be significantly magnified even by small offset of the sensitivity axis from the geometric center of an accelerometer, accurate measurement of sensitivity axis must be preceded. The method for accurate estimation of the offset was proposed, and the effect of offset on the estimation of angular acceleration was investigated.
Dynamic Analysis of the Power Transmission System in an Industrial Robot
Kim, Woo-Hyung ; Chung, Jin-Tai ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 913~919
DOI : 10.5050/KSNVN.2008.18.9.913
Dynamic characteristics of a wrist power transmission of an industrial robot are studied. The wrist power transmission has complex structure characteristics, because it is composed with several shafts and gear system. We used an analytical method to investigate the dynamic characteristics. An analytical model is a rigid model which is composed with masses and springs. Both bearing and gear contact model represent equivalent stiffness springs which are determined by the experiment. In order to investigate the dynamic tendency of the robot wrist power transmission, we simulate the analytical model. There is a dynamic analysis tool which is called the RecurDyn. To verify the analytic results, we experiment a signal analysis which is an overall noise level of the robot. By the parametric study of the element of the robot, we study an improvement method of dynamic characteristics.
Study on the Noise Reduction in the Rotary Compressor Using BLDC Motor
Kim, Jin-Soo ; Lim, Kyung-Nae ; Ku, Se-Jin ; Lee, Jang-Woo ; Jeon, Si-Moon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 920~929
DOI : 10.5050/KSNVN.2008.18.9.920
The main noise and vibration source of the BLDC rotary compressor for air conditioner was analyzed by using the measurement of noise and vibration, noise contour, and experimental modal analysis. The source is presumed to the mechanical resonance excited by the electromagnetic attractive force of the BLDC motor. To reduce the excessive noise of the BLDC rotary compressor due to the mechanical resonance, air-gap enlargement and structural dynamic modification were applied in this paper. Its validations were conducted by the analysis of the electromagnetic attractive force which is generated by the BLDC motor and by the measurement of noise and vibration of the BLDC rotary compressor. By enlarging the length of air-gap and conducting the structural dynamic modification, the noise and vibration in the compressor was significantly improved by 4.5 dB(A) and 56 percent, respectively.
Vibroacoustics of Axisymmetric Cylindrical Elastic Shells : Wall Impedance of the Plane Mode
Park, Chan-Il ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 930~936
DOI : 10.5050/KSNVN.2008.18.9.930
Fluid loading of a vibrating cylindrical shell has influence on natural frequencies and vibration magnitudes of the shell and the acoustic pressure of fluid. The vibroacoustics of fluid-filled cylindrical shells need the coupled solution of Helmholtz equation and governing equation of a cylindrical shell with boundary conditions. This paper proposed the wall impedance of fluid-filled axisymmetric cylindrical shells, focusing on the inner fluid/shell interaction. To propose the impedance, shell displacements used the linear combination of in vacuo shell modes. Acoustic pressure prediction of fluid used Kirchhoff-Helmholtz integral equation with Green`s function of the plane mode. For the demonstration of the proposed results, numerical applications on mufflers were conducted.
Identification on Fatigue Failure of Impeller at Single Stage Feedwater Pumps During Commissioning Operation
Kim, Yeon-Whan ; Kim, Kye-Yean ; Bae, Chun-Hee ; Lee, Young-Shin ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 937~942
DOI : 10.5050/KSNVN.2008.18.9.937
This paper presents a case history on failures of impeller and shaft due to pressure pulsation at single stage feed water pumps in 700 MW nuclear power plant during commissioning operation. The pumps had been service and had run for approximately
hours. For the most part, the failures of impeller occurred with the presence of a number of fatigue cracks. All cracks were associated with the deleterious surface layer of impeller by visual and metallurgical examination. On-site testing and analytical approach was performed on the systems to diagnose the problem and develop a solution to reduce the effect of exciting sources. A major concern at high-energy centrifugal pump is the pressure pulsation created from trailing edge of the Impeller blade, flow separation and recirculation at centrifugal pumps of partial load. Pressure pulsation due to the interaction generating between impeller and casing coincided with natural frequencies of the impeller and shaft system during 1ow load operation. It was identified that dynamic stress exceeding the fatigue strength of the material at the thin shroud section due to the hydraulic instability at running condition below BEP.
The Mathematical Model on Crosstalk Effect of Airborne Noise Sources and Verification based on Comparison between Transfer Path Analysis Methods
Byun, Jae-Hwan ; Kim, Yoon-Jae ; Kang, Yeon-June ; Kang, Koo-Tae ; Kwon, O-Jun ; Hong, Jin-Chul ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 943~951
DOI : 10.5050/KSNVN.2008.18.9.943
In this paper, the mathematical model on crosstalk effect between acoustic noise sources is presented. Based on this model, a theoretical value to quantitate crosstalk effect of sources can be defined on the authority of reverberation property of surrounding which sources are located, relative magnitudes of sources and phase deference between acoustic wave transferred from all of sources. In order to verify crosstalk effect factor, experiments are made for two cases, weak and strong crosstalk effect condition, by using toro representative transfer path analysis(TPA) methods.
Fan Noise Prediction Method of Air Cooling System
Lee, Chan ; Kil, Hyun-Gwon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 952~960
DOI : 10.5050/KSNVN.2008.18.9.952
Fan noise prediction method is presented for air conditioning, automobile and electronic cooling system applications where fan acts as an internal equipment having very complicated flow interaction with other various system components. The internal flow paths and distribution in the fan-applied systems such as computer or air conditioner are analyzed by using the FNM(flow network modeling). Fan noise prediction method comprises two models for the discrete frequency noise due to rotating steady aerodynamic lift and blade interaction and for the broadband noise due to turbulent boundary layer and wake vortex shedding. Based on the fan operation point predicted from the FNM analysis results and fan design parameters, the present far noise model predicts overall sound pressure level and spectrum. The predictions for the flow distribution, the fan operation and the noise level in air cooling system by the present method are well agreed with 3-D CFD and actual noise test results.
A Study on the Vibration Characteristics of Critical Speed for Rotor Shaft
Son, Choong-Yul ; Lee, Kang-Su ; Ryu, Young-Hyun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 961~971
DOI : 10.5050/KSNVN.2008.18.9.961
In the design of a rotor shaft, care should be taken to minimize vibration by taking into account the sources of vibration. In addition, the intensity critical speed, stability, and other related aspects of the system must be considered. especially when it is operated at a critical speed, it is important to address issues related to vibration, as an increase in the whirling response of the rotor shaft can cause damage to the shaft, destruction of the rotor parts, and detrimental abrasions on the bearings. In this thesis, the vibration characteristics of a rotor shaft are investigated through the use of the finite element method. Variations of the diameters and lengths were used to determine the effect of a rotor shaft using Beam No.188(3D linear strain beam) in ANSYS version 11.0 as a universal interpretation program for finite elements. Special care was taken to prevent excessive vibration, which can result from resonance at the initial stage, in the formulation of a dynamic design for a rotor shaft through calculations while changing the diameters and the lengths of the shaft. Moreover, the dynamic characteristics of the critical speed, total mass, D/L(diameter to length) ratio, and natural frequency were verified. Furthermore, the rotor shaft applied by bearing element was calculated and compared by using Combi No. 214(2-D spring-damper bearing).
Structural Modification for Noise Reduction of the Blower Case in a Fuel Cell Passenger Car Based on the CAE Technology
Song, Min-Keun ; Lee, Sang-Kwon ; Seo, Sang-Hoon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 972~981
DOI : 10.5050/KSNVN.2008.18.9.972
The blower which is installed in a FCEV(fuel cell electric vehicle) may cause noise due to misalignment and unbalance of mechanical components that rotate at high speed. One of the key points in efforts to minimize the noise radiation from a blower is the knowledge of the main radiating component and the relation between the surface vibration of a blower and the sound pressure. In this research, the blower model is developed based on FEM(finite element method). FE(finite element) model is reliable by correlation of frequencies and MAC(modal assurance criterion) values between EMA(experimental modal analysis) and FEA(finite element analysis). This model is applied to predict the vibration of a blower by using inverse force identification method and predict the radiating noise by using BEM(boundary element method). Comparing the frequencies of resonance and those mode shapes between EMA and FEA, a structural modification of the FE model is evaluated for reducing the parameters of the blower noise.
An Experimental Study on the Noise and Vibration Characteristics of LCD TV Inverter
You, Chung-Jun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 18, issue 9, 2008, Pages 982~989
DOI : 10.5050/KSNVN.2008.18.9.982
There is a noticeable hum from the inverter board of LCD TV when in operation. In this study, we investigate the source and the characteristics of this noise for the inverter board of LCD TV using measurement of vibration and noise. Modal analysis of vibration and noise is visualized for identification of noise sources and transmission vibration. The main source of noise was the transformer of the LCD TV inverter. A noise reduction was achieved by damping the structural elements.