• International Journal of Vascular Biomedical Engineering
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• v.1 no.2
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• pp.4-12
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• 2003

The present study investigated the effect of transverse vibration on the hemorheological characteristics of blood using a newly designed pressure-scanning capillary viscometer. As vibration was applied, aggregated blood cells (rouleaux) were disaggregated. The range of vibration frequency and amplitude are $0{\sim}100\;Hz$ and $0{\sim}0.8\;mm$, respectively for a capillary diameter 0.84 mm. As vibration increased, blood viscosity initially increased and tended to decrease. In order to delineate the unexpected results, the present study proposed two counteracting mechanisms of vibration related with red blood cell (RBC) aggregation affecting hemo-rheological properties. One is the reduction of RBC aggregation due to vibration causing an increase of blood viscosity. The other is forced cell migration due to the transverse vibration, which in turn forms a cell-free layer near the tube wall and causes a decrease of flow resistance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1373-1378
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• 2000

Vibration caused by railroad vehicle including subway train running raises a lot of problems to the neighboring buildings. Therefore lots of methods to isolate the railway vibration have been studied and practically applied to sites. As one of them, specially designed vibration isolation device was installed in the some section of Seoul subway. This device is installed between the rail and track slab. Because the process of installation is relatively simple, this method can be applied to the existing railways in servicing. We measured the vibration and noise to check the effectiveness of this device before and after the installation. The result showed that the vibration level of the slab and platform was reduced to 7 - 10 dB. Expecially high frequency component was reduced to a large amount. From this result, we can conclude that these kind of devices are useful to the reduction of the railroad vibration, expecially the high frequency vibration which can cause structure born noise.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1116-1122
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• 2008

The reciprocating type hydrogen compressor has a pulsation due to the reciprocative characteristics which results in noise and vibration. Snubber is installed for the relaxation of pulsation, but it causes reduction of compressor efficiency because of pressure loss. Five types of snubber were modeled for the numerical investigation of the effect of the relative position of inlet and outlet and buffer angle on the pulsation amplitude and pressure loss. MSC/NASTRAN is used as a numerical tool to identify the vibration characteristic of each type. Frequency responses in forced vibration mode are compared for various cases and buffer angles.

• Journal of KSNVE
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• v.9 no.4
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• pp.693-702
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• 1999

We study the characteristics of airflow and sound noise induced by disk rotation in optical disk drives. The characteristics of airflow around a rotating disk surrounded by various tray structures are numerically investigated using a commercial CFD program and then compared with experimental results. Sound pressure and intensity caused by the fluid-structure interactions in the CD/DVD-ROM drive are measured, and the effect of the ariflow on the sound noise and disk vibration is discussed. In order to reduce airflow-induced noise and vibration around the rotating disk, tray geometry is modified. Both numerical and experimental studies implemented with different tray models show that the improved tray model alters the characteristics of the disk-induced airflow, causing the reduction of the airflow-induced sound level.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.55-57
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• 1999

SRM Drives generate large vibration and acoustic noise because it is rotated by step pulse mmf and switching commutation mechanism. The main vibration source of SRM Drive is generated by rapidly variation of radial force when phase winding current is extinguished for commutation action. So the rapidly variation of radial force is repressed firstly to reduce vibrating force of SRM Drive. This paper suggests the vibration reduction method that SRM Drive with unidirect-short compensation winding is excited by a two stage commutation method at commutation period. This reduction effect of vibration is verified with the result obtained in the test of prototype machine.

• Journal of Environmental Impact Assessment
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• v.23 no.3
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• pp.169-176
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• 2014

The purpose of this study is to estimate the vibration reduction effect of the borehole which is controlled the vibration propagation in the ground. For this study, we measured the vibration velocity before and after the borehole installation. The results are as follows: The peak particle velocity(PPV) and peak vector sum(PVS) was reduced by the borehole. And also, the deviation of vibration velocity before and after the borehole installation showed large values in longitudinal and vertical component depending on the receive distance, and increased depending on the size of vibration energy. Finally, the vibration isolation efficiency was 25~35 percentage at 1.5m receive distance, and was 4~14 percentage at 3.0m receive distance. It was found that the vibration isolation efficiency was good in small vibration energy, but was not good at long receive distance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.54-61
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• 2013

Stay cable has a strong axial rigidity due to large initial tension and, on the other hand, it has a weak laterally flexural rigidity. Wind loads or traffic loads cause the cables to vibrate significantly and affect the mechanical properties and the performance of cables of cable-stayed bridge (CSB). Therefore, the development of vibration reduction design is an urgent task to control the vibration vulnerable long-span bridges. As Friction damper (FD) shows to reduce the amplitude and duration time of vibration of cable of CSB from measured date in field test, friction damper can be considered that it is effective device significantly to reduce the amplitude and duration time in vibration of cable of CSB under traffic load, wind load and so on. Vibration characteristics of cable can change according to manufacturing method and type of established form. Nevertheless, analysis method in this study can present the design of friction damper for vibration reduction of cable of cable-stayed bridge from now on.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.7
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• pp.532-538
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• 2003

This paper studies on the noise reduction for a small automobile DC Motor (a window motor) using the 6 sigma process. The application of 6 sigma process suggested reliable and valuable statistical data for the quality of the DC motor at the production line. In the measurement step in 6 sigma process. the FMEA(failure mode effect analysis) were used for the detection of noise sources. The application of 6 sigma Process gave not only the improving method for the quality of the DC motor but also the confidence of improvement Itself since it was done on the basis of the test results for a number of DC motors at the production line. Consequently the 6 sigma process was proved very effective for the noise reduction at the production line.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.644-647
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• 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 Power System Engineering
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• v.11 no.2
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• pp.32-37
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• 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.