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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 17, Issue 12 - Dec 2007
Volume 17, Issue 11 - Nov 2007
Volume 17, Issue 10 - Oct 2007
Volume 17, Issue 9 - Sep 2007
Volume 17, Issue 8 - Aug 2007
Volume 17, Issue 7 - Jul 2007
Volume 17, Issue 6 - Jun 2007
Volume 17, Issue 5 - May 2007
Volume 17, Issue 4 - Apr 2007
Volume 17, Issue 3 - Mar 2007
Volume 17, Issue 2 - Feb 2007
Volume 17, Issue 1 - Jan 2007
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A Research on the Vibration Characteristics of Vehicle due to Speaker Sound at Low Frequency
Kim, Ki-Chang ; Kim, Chan-Mook ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 673~682
DOI : 10.5050/KSNVN.2007.17.8.673
Recently the trend of automobile industry is that IQS evaluation index against a sensitivity quality is increasing. To reduce rattle noise due to speaker sound at low frequencies, it is required the advanced technology analysis process of body structure. This paper optimized the design parameters of package tray panel according to the theoretical background about robust design and suggested the design guideline for resonance avoidance and the reduction of vibrational sensitivity considering the excitation frequency of woofer speaker. And this paper described the design process of a door module panel through the sensitivity analysis in case of the door speaker excitation. Finally, the analysis of the quality deviation using mother car is suggested to guarantee the stable characteristics of vehicle vibration in the early stage of vehicle development. These improvements can lead to shortening the time needed to develop better vehicles.
Low-noise Design of Passage of Idle Speed Control Actuator In Automotive Engines Using Scaling Laws for Noise Prediction
Cheong, Cheol-Ung ; Kim, Jae-Hyun ; Kim, Sung-Tae ; Park, Yong-Hwan ; Lee, Soo-Gab ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 683~692
DOI : 10.5050/KSNVN.2007.17.8.683
Recently, plastic products in air-intake parts of automotive engines have become very popular due to advantages that include reduced weight, constricted cost, and lower intake air temperature. However, flow-induced noise in air-intake parts becomes a more serious problem for plastic intake-manifolds than for conventional aluminum-made manifolds. This is due to the fact that plastic manifolds transmit more noise owing to their lower material density. Internal aerodynamic noise from an idle speed control actuator(ISA) is qualitatively analyzed by using a scaling law, which is expressed with some flow parameters such as pressure drop, maximum flow velocity, and turbulence kinetic energy. First, basic flow characteristics through ISA passage are identified with the flow predictions obtained by applying computational fluid dynamics techniques. Then, the effects on ISA passage noise of each design factors including the duct turning shape and vane geometries are assessed. Based on these results, the preliminary low noise design for the ISA passage are proposed. The current method for the prediction of internal aerodynamic noise consists of the steady CFD and the scaling laws for the noise prediction. This combination is most cost-effective, compared with other methods, and therefore is believed to be suited for the preliminary design tool in the industrial field.
Spatial Complex Envelope of Acoustic Field : Its Definition and Characteristics
Park, Choon-Su ; Kim, Yang-Hann ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 693~700
DOI : 10.5050/KSNVN.2007.17.8.693
We can predict spatial acoustic pressure distribution on the plane of interest by using acoustic holography. However, the information embedded in the distribution plot is usually much more than what we need: for example, source locations and their overall propagation pattern. One possible candidate to solve the problem is complex envelope analysis. Complex envelope analysis extracts slowly-varying envelope signal from a band signal. We have attempted to extend this method to space domain so that we can have spatial information that we need. We have to modulate two dimensional data for obtaining spatial envelope. Although spatial modulation basically follows the same concept that is used in time domain, the algorithm for the spatial modulation turns out to be different from temporal modulation. We briefly describe temporal complex envelope analysis and extend it to spatial envelope of 2-D acoustic field by introducing geometric transformation. In the end, the results of applying the spatial envelope to the holography are envisaged and verified.
Stability Analysis of a Rotating Cantilever Pipe Conveying Fluid
Son, In-Soo ; Yoon, Han-Ik ; Kim, Dong-Jin ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 701~707
DOI : 10.5050/KSNVN.2007.17.8.701
In this paper the vibration system is composed of a rotating cantilever pipe conveying fluid. The equation of motion is derived by using the Lagrange's equation. Generally, the system of pipe conveying fluid becomes unstable by flutter. Therefore, the influence of the rotating angular velocity, mass ratio and the velocity of fluid flow on the stability of a cantilever pipe by the numerical method are studied. The influence of mass ratio, the velocity of fluid, the angular velocity of a cantilever pipe and the coupling of these factors on the stability of a cantilever pipe are analytically clarified. The critical fluid velocity (
) is proportional to the angular velocity of the cantilever pipe. In this paper Flutter(instability) is always occurred in the second mode of the system.
Evaluation of Acoustic Performance about Dome-typed Gymnastics Training Floor Using Auralization
Yun, Jae-Hyun ; Ju, Duck-Hoon ; Kim, Jae-Soo ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 708~719
DOI : 10.5050/KSNVN.2007.17.8.708
In case of indoor gymnastics training floor, in view of its characteristics, since it is simultaneously required the related smooth communication between the coach and the player, also the acoustic performance regarding to the clearness of music, besides the sport activity, the consideration about the acoustic character has entered the stage as an indispensable element. On such viewpoint, recently constructed dome-typed gymnastic training floor was optimized acoustic design with remodeling through acoustic simulation test. And acoustic satisfaction degree and reaction was attempted to investigate about the gymnastics training floor estimating value of human's psychological(sensual) degree using auralization that enables to experience the virtual sound field at the stage of design. As the result of investigation about the research on the space of object, it could be known that the valuation regarding to the acoustic performance of 'after-improvement' was distinctly more refined than that of 'before-improvement'. It is now considering that such result of the study can be utilized as the useful data which enables to improve the retrenchment effect of the construction cost as well as the acoustic capability, by means of the prediction control on the acoustic problem from the stage of design, for the occasion when the similar indoor sport gymnasium is planning to build for the near future.
Correction of Mass Unbalance of a High Precision Rotor
Lee, S.B. ; Ihn, Y.S. ; Oh, D.H. ; Kim, H.Y. ; Lee, H.S. ; Koo, J.C. ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 720~725
DOI : 10.5050/KSNVN.2007.17.8.720
The unbalanced mass of a high precision rotor deteriorates mechanical performance of the rotor. The geometrical center of a rotor generally corresponds to the rotational axis of the rotor. However, this alignment carried out with a stationary rotor does not guarantee the dynamic rotor balance. There have been a number of schemes for the correction of the unbalance published for decades especially in the hard drive industry where the issues are directly affecting manufacturing costs and product performances. Realizing the significance of the problem, the present work tries to refine one of the methods that works by applying external impact during a rotor spins. A systematic way to apply the external impact to a rotating rotor has been introduced to minimize unbalance correction process time.
An Analysis and Assessment of Transient Vibration Phenomenon for Precision Equipment Due to Adjacent Utility Operation in TFT-LCD Fab
Baek, Jae-Ho ; Lee, Hong-Ki ; Son, Sung-Wan ; Chun, Chong-Keun ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 726~735
DOI : 10.5050/KSNVN.2007.17.8.726
Inside the factory buildings of aprecision industry (which produces semiconductors or TFT-LCD), thousands of vibration-sensitive precision equipments operate in the clean rooms. Various utility equipments that are installed around them for proper operation cause various sources of noise and of vibration to exist inside the clean rooms and thus deteriorate the noise and the vibration environment within. In this study, we check if the existing transient vibration phenomenon is caused by the vibrations that arise from operating the utility installed near these equipments; compare and evaluate the vibration criteria of precision equipments regarding the transient vibration phenomenon; and check the efficiency of these criteria.
A Laboratory Study on Low Frequency Noise Assessment based on Noise Acceptability Limit
Hong, Seung-Ki ; Kim, Jae-Hwan ; Kim, Kyu-Tae ; Lee, Soo-Gab ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 736~740
DOI : 10.5050/KSNVN.2007.17.8.736
A laboratory study on low frequency noise assessment has been carried out to evaluate the relevance of the weighting curve. Especially, the A-weighting curve which is used in most noise assessments has been evaluated using the acceptability limit in this study. The acceptability limit is one of the indicators in which the subjective responses were well-reflected. For the measurement of the acceptability limit, pure tone stimuli were used in the frequency range between 20 and 200 Hz. The measurement was proceeded in the anechoic chamber to minimize the background noise level. A total of 29 test subjects, who were aged between 19 to 33 years, participated in this study. They had been exposed to various stimuli for about 1 hour by supra-aural earphone. The measurement consisted of two listening sessions: hearing threshold and the acceptability limit session. The results showed that the tendency of the acceptability limit curve was approximately equal to C-weighting curve which had been found to be superior to A-weighting curve in assessment of low frequencies.
A Study on Vibration Transfer Path Identification of Vehicle Driver's Position by Multi-dimensional Spectral Analysis
Lee, You-Yub ; Park, Sang-Gil ; Oh, Jae-Eung ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 741~746
DOI : 10.5050/KSNVN.2007.17.8.741
In this study, transfer path identification and output estimation are simulated by multi-dimension spectral analysis method (MDSA). Multi -input/single-output system give expression the vehicle suspension which each inputs are correlated reciprocally. In case of correlating with inputs, the system needs separating the each input signal by MDSA. Main simulations are about finding effective input by coherent output spectrum and selecting optimal input's number by multiple coherence function. Also, by shielding transfer path of each input, transfer path characteristic is identified in terms of overall integrated contribution level.
A Study on the Dynamic Characteristics of Hydropneumatic Suspension Unit Considering the Nonlinear Effects
Song, Oh-Seop ; Park, Byung-Hoon ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 747~756
DOI : 10.5050/KSNVN.2007.17.8.747
The hydropneumatic suspension units, which have applied to the tracked vehicles, have the spring and damping function in the unit. The nonlinear characteristics such as roadwheel rotation effects, gas behavior changes, hydraulic damping characteristics, hysterisis, and frictional forces have been ignored or simplified to analyze the mathematical models in many areas. This study describes the dynamic characteristics and the nonlinear behaviors of hydropneumatic suspension unit considering the nonlinear effects such as the nonlinear spring and nonlinear damping through the simulation and the experiment. The utility of nonlinear analysis through the higher-order spectral analysis is also presented.
Enhanced PSPICE Circuit Model for Vented-Box Loudspeaker System
Park, Seok-Tae ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 757~765
DOI : 10.5050/KSNVN.2007.17.8.757
Enhanced PSPICE circuit model for vented-box loudspeaker system with lumped parameters was proposed to more accurately simulate real vented-box loudspeaker system. Frequency dependent parameters were used to model voice coil inductor. Acoustic pressure response curves and electrical impedance curves were simulated and investigated by PSPICE circuit model according to circuit parameters' variations. Finally, it was used to identify faults detection in woofers manufactured by unskilled persons.
Sensitivity Analysis Using TPA for Slosh Noise of Fuel Tank
Cha, Hee-Bum ; Yoon, Seong-Ho ;
Transactions of the Korean Society for Noise and Vibration Engineering, volume 17, issue 8, 2007, Pages 766~770
DOI : 10.5050/KSNVN.2007.17.8.766
Fuel sloshing in a vehicle fuel tank generates a reluctant low frequency noise, called slosh noise. To reduce slosh noise, whilst many approaches have used the Computational Fluid Dynamics method to first identify fuel behavior in a fuel tank, this paper applies the Transfer Path Analysis method. It is to find contribution of each transfer path from noise transfer function, vibration transfer function and acceleration. Then the final goal is to attenuate slosh noise by controlling them. To this aim, two types of models are studied. One is the decoupled model in which some of connection points of the fuel tank with the vehicle underbody are separated. The other is the modified model which is created by changing noise transfer function and acceleration from the original model. The analysis and validation test results show that the transfer path analysis can be an approach to enhancing slosh noise.