• Journal of Power System Engineering
• /
• v.11 no.2
• /
• pp.32-37
• /
• 2007

The present study describes the effects of music and vibroacoustic stimuli to the relaxation of human body. We have carried out the experiment on 6 human subjects of which are composed 3 men and 3 women. We have investigated the electroencephalogram(EEG) of all subjects before and after the stimuli of which are made a strong noise or the meditatiom music and the acoustic vibration. The vibroacoustic device has transmitted meditation music as vibration between 20Hz and 250Hz to the body. From the experimental results, we made sure the effects that the meditation music and vibroacoustic stimuli influenced the stress reduction of human body for good as alpha wave was increased continuously during the good stimuli and after that.

• Journal of Power System Engineering
• /
• v.14 no.4
• /
• pp.29-36
• /
• 2010

This study was performed with 5 subjects and used three kinds of music and vibroacoustic stimuli wave based upon each kinds of music. Executing music stimulation, vibro tactile and acoustic wave stimulation to human body were performed. Then measured brain waves were analyzed under each condition including before stimulation, stimulation 1, and stimulation 2. Effects by stimulation results could be studied with experiments and summarized results are followings. 1. It may be concluded that effects on brain waves by music and vibroacoustic stimulation might differ under different situations such as stimulation types with vibroacoustic equipment, human body and mental conditions when measuring, etc.. 2. During stimuli by using music A, B, and C, the effect of $\alpha$ wave, $\beta$ wave, and SMR wave power values show same tendency to the subject c but music C had very different tendency during vibroacoustic stimuli. 3. During vibroacoustic stimuli by applying the signals of music C, because SMR wave power value was continually increased with consistency comparing to Bst, this can be estimated that an application of inducing mind concentration condition would be possible under relaxed body and mind conditions. 4. To secure data significance, all measured data need to be tested statistically whether data would be interrelated or not.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.644-647
• /
• 2007

In this paper, we present our method of controlling the transmission path of compressor vibration to reduce the vibroacoustic of refrigerator. Firstly, to reduce the vibroacoustic radiated from compressor _ mount system, main transmission path was found experimentally and applied partial contact to transmission path to minimize the transmissibility from compressor operation to base plate. In order to verify our method, we designed changing of the connection part between grommet and base plate. Through experiment with modified connection part, we certificate experimentally the noise reduction of refrigerator. Finally, we apply previous connection part to grommet inner shape to enhance the effect of the system. From experimental results, we make certain the possibility of noise reduction of refrigerator through this approach.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.2
• /
• pp.82-89
• /
• 2006

The flutter/vibroacoustic characteristics can be acquired by conducting flight tests with various conditions for a long period of test. Accordingly it is indispensable to build a specially designed database system to efficiently accumulate the enormous data obtained from flight tests. Hence, T-50 Flight Test Database System(FTDS) based on MS-Access is developed to handle the flutter/vibroacoustic environment data obtained from flight tests. The developed system is structured with the items related to aircraft flight test, the tables composed of the relevant items and a relational database logically connecting the tables. The T-50 FTDS is implemented with data searching GUI(Graphic User Interface) programed with Visual Basic and Structured Query Language to make intuitive searches over the stored data. The developed system has been used for accumulating the flutter/vibroacoustic data and verifying vibroacoustic Specifications.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1996.10a
• /
• pp.135-141
• /
• 1996

Numerical analysis techniques have been applied to obtain the vibroacoustic characteristics of the simplified model of a passenger-car cabin. Two kinds of coupled vibration-acoustic analysis, such as one-way coupling and full coupling, have been carried out via the interface between the results of vibration analysis by FEM and acoustic analysis by BEM. The comparison of two coupled analysis results show the fluid-structure interaction in terms of the coupled effect of the vibration and noise.

• Journal of Power System Engineering
• /
• v.12 no.5
• /
• pp.59-64
• /
• 2008

The present paper describes the effects on human body by music and vibroacoustic stimuli. The experiments were carried out six times for 3 subjects and have investigated the electroencephalogram of all subjects against six music stimulus having vibration or non-vibration. From the experimental results, we can distinguish which musics were useful for a relexation and a reduction of stress or effective for power of concentration. We made sure that the music and the vibroacoustic stimuli have been the more effective and the more sensitive than the only music stimuli. And the close investigation and examination to the effect of acoustic vibrations will be applied for healing of a disease and so on.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.10
• /
• pp.1196-1203
• /
• 2011

Statistical optimum methodology of table of orthogonal array, ANOM, ANOVA and RSM are applied to formulate optimum allocation design with design variables. It can be minimized average SPL of control volume, the objective function in closed system by optimal allocated positions of absorbing material. Structural natural frequency and acoustic natural frequency of cavity are analyzed by FEM and BEM in the closed system. Using BEM, average SPL of specific control volume is calculated according to the condition before using absorbing material and after using it. It is shown that noise is reduced by $5.02dB_{RMS}$ by absorbing material located at optimal position and minimum $1.83dB_{RMS}$ and maximum $3.47dB_{RMS}$ by the table of orthogonal array.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.325-333
• /
• 2000

To predict vibrational energy density and intensity of partitioned complex system structures in medium-to-high frequency ranges, Power Flow Finite Element Method(PFFEM) programs for the plate elements are developed. The flexural, longitudinal and shear waves in plates are formulated and the joint element equations for multi-couped plates are fully developed. Also the wave transmission approach has been introduced to cover the energy transmission and reflection at the joint plate elements. Using the developed PFFEM program the energy density and intensity of the submarine and automobile shape structures are predicted with a harmonic point force at a single frequency.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.2
• /
• pp.168-175
• /
• 2001

Reduction of structure-borne noise of the compartment in a car is an important task in automotive engineering. Transfer path analysis using vibroacoustic reciprocity technique or multiple path decomposition method has generally been used for structure-borne noise path analysis. These methods are useful in solving particular problem but do net quantify the effectiveness of vibration isolation of each isolator of a vehicle. To quantify the effectiveness of vibration isolation, the vibrational power flow has been used for a simple isolation system or a laboratory based isolation system. It is often difficult to apply the vibrational power flow technique to the complex isolation system like a car. In this paper, a simple equation is derived for calculation of the vibrational power flow of an isolation system with multiple isolators such as a car. It is successfully applied to not only quantifying the relative contributions of eighteen isolators but also reducing structure-borne noise of a passenger car. According to the results, the main contributor of eighteen isolators is the rear roll mount of an engine. The reduced structure-borne noise level is about 5dBA.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.11a
• /
• pp.208-214
• /
• 2000

Reduction of structure-borne noise of the compartment in a car is an important task in automotive engineering. Transfer path analysis using vibroacoustic reciprocity technique or multiple path decomposition method has generally been used for structure-borne noise path analysis. These methods are useful in solving particular problem but do not quantify the effectiveness of vibration isolation of each isolator of a vehicle. To quantify the effectiveness of vibration isolation, the vibrational power flow has been used for a simple isolation system or a laboratory based isolation system. It is often difficult to apply the vibrational power flow technique to the complex isolation system like a car. In this paper, a simple equation is derived for calculation of the vibrational power flow of an isolation system with multiple isolators such as a car. It is successfully applied to not only quantifying the relative contributions of eighteen isolators but also reducing structure-borne noise of a passenger car. According to the results, the main contributor of eighteen isolators is the rear roll mount of an engine. The reduced structure-borne noise level is about 5dBA.