• The Korean Journal of Ecology
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• v.21 no.5_2
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• pp.491-499
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• 1998

An investigation was performed to establish the mathematical theories of a vibration for the plant growth and a wave distribution of a plant population on the boundary condition of a limiting factor in the environment. The mathematical theories of the plant growth vibration and wave distribution had been elucidated by the plant growth and the timber line on the middle slope of the west side of Mt. Paektu. The Betula ermaruii composes the timber line on about 2,060 m elevation of sea label, has a growth vibration on the ground surface and takes a wave distribution due to a boundary condition of alpine temperature gradient.

• Journal of Nutrition and Health
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• v.9 no.4
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• pp.11-18
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• 1976

In this third report influence of vibration on growth and on some metabolism of young growing rats fed on varying levels of protein was investigated. Forty eight (48) young growing male rats weighing about 60 grams were used, grouping to four (4) groups, twelve (12) rats each group. They were fed on 8%, 13%, 19%, and 26% casein diet respectively (See the table 1) for the period of 10 weeks experiment. During the experimental period the half number of the rats of each group were subjected to a given degree of vibration for two (2) hours daily. Observations for growth rate, food and protein efficiency ratios, organs development, cholesterol levels in aorta, total nitrogen, urea nitrogen and creatinine levels in urine may be summarized as follows 1. Growth was impaired by the vibration in all groups including 26% easein diet. 2. There is tendeney that in higher protein diets, the organs (See table 3) developed more well. And also the impairment of the organs development by the vibration revealed less in higher protein diets. 3. Food and protein efficiency ratios were generally decreased under vibration and the food efficiency was improved by increasing the protein level in diet. 4. Total and free cholesteral levels in aorta were increased by the vibration. Ester from/tatal ratio was 17.7% and 17.3% respectively at 8% and 13% protein diets and 54.8% and 54.2% at 19% and 26% protein diets. These show that, in higher protein diets, the vibration doesn't influence the cholesterol ratio. 5. Total nitrogen, urea nirogen and creatinine levels in urine were increased by increasing the protion level in diet and also increased by the vibration. 6. It seems that, according to the above observations, the vibration used in this experiment influenced, in certain extent, on physical development, physiological availability of nutrients, and on body metabolism. And it is also thought that higher protein diets act some good role in protecting body from suffering from vibration.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4561-4569
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• 2023

A correct understanding of vibration-based degradation is crucial from the standpoint of maintenance for Steam Generators (SG) as crucial mechanical equipment in nuclear power plants. This study has established a novel approach to developing a model for investigating tube bundle degradation according to crack growth caused by two-phase Flow-Induced Vibration (FIV). An important step in the approach is to calculate the two-phase flow field parameters between the SG tube bundles in various zones using the porous media model to determine the velocity and vapor volume fraction. Afterward, to determine the vibration properties of the tube bundles, the Fluid-Solid Interaction (FSI) analysis is performed in eighteen thermal-hydraulic zones. Tube bundle degradation based on crack growth using the sixteen most probable initial cracks and within each SG thermal-hydraulic zone is performed to calculate useful lifetime. Large Eddy Simulation (LES) model, Paris law, and Wiener process model are considered to model the turbulent crossflow around the tube bundles, simulation of elliptical crack growth due to the vibration characteristics, and estimation of SG tube bundles degradation, respectively. The analysis shows that the tube deforms most noticeably in the zone with the highest velocity. As a result, cracks propagate more quickly in the tube with a higher height. In all simulations based on different initial crack sizes, it was observed that zone 16 experiences the greatest deformation and, subsequently, the fastest degradation, with a velocity and vapor volume fraction of 0.5 m/s and 0.4, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.82-83
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• 2008

In the cases of high speed railway bridge, dynamic behavior analysis is important because of high passing velocity and moving load at the regular intervals, and the damping ratio is a major element in dynamic behavior analysis. In this paper, damping ratios were estimated by two methods and vibration type sections, and relationship between estimated damping ratio and representative value of bridge vibration. At the results, estimated damping ratio using all time of vibration were more stable then using only free vibration section. And in the case of using extended Kalman filter, estimated damping ratio were trend of growth by growth of representative value of bridge vibration. At last, it was shown that study about reliabilities of estimated damping ratios were need.

• Journal of Biomedical Engineering Research
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• v.45 no.4
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• pp.195-203
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• 2024

Muscle disorders arise from genetic factors or other external environmental influences, leading to muscle loss and decreased strength. Muscle disease is closely related to age, and with the global progression of aging, there is increasing interest in the prevention and treatment of muscle diseases among the elderly population. Muscles release various substances during contraction and relaxation when exercising, and growth and differentiation are enhanced. Similar effects can be achieved by vibration stimulations of specific frequencies. To examine the response of muscle cells to vibration stimuli, an in vitro vibration device capable of setting various frequencies and amplitudes was developed for use with a 6-well plate. In vitro vibrational stimulation was applied to C2C12 myoblasts to quantify the growth and differentiation of myoblasts, as well as cell apoptosis. 10 Hz vibrational stimuli resulted in increases in ERK signaling and decreases in cell death. Moreover, an increase in the number of exposures to vibration promoted cellular differentiation. In conclusion, 10 Hz vibrational stimuli have the potential to increase muscle growth and differentiation and reduce apoptosis in C2C12 myoblasts.

• Journal of Korea Foundry Society
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• v.17 no.2
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• pp.188-194
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• 1997

The effects of solidification condition and vibration on structure refinement were investigated for unidirectionally solidified $Al-CuAl_2$ eutectic composites. Eutectic composites were unidirectionally solidified under vibration with different growth rates (R) and thermal gradient(G). The lamellar structure was varied according to growth condition (G/R ratio). For the structure refinement the effect of G/R was found out to be greater than that of vibration. The interlamellar spacing(${\lambda}$) in this materials was varied with the growth rates(R) with "${\lambda}^2R$=Constant" relationship.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.274-278
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• 2014

Machining performance is often limited by chatter vibration at the tool-workpiece interface. Chatter vibration is a type of machining self-excited vibration which originated from the variation in cutting forces and the flexibility of the machine tool structure. Cutting tooling method is one of major factor to chatter vibration in turning process. Even though lots of cutting tooling methods are developed and used in machining process, precise analysis of cutting tooling effect in view of chatter vibration behavior. This study presents numerical and experimental approaches to verify and effects of various cutting tooling geometry and clamping method on the onset of chatter vibration. Acquired knowledge from this study will apply the optimal geometry design of cutting tooling and adjusting of machining process.

• Korean Journal of Materials Research
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• v.4 no.2
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• pp.177-186
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• 1994

The effect of solidification condition and vibration on structure refinement was investigatedfor unidirectionally solidified $AI-CuAI_{2}$ eutectic composites. Eutectic composites were unidirectionally solidifiedunder vibration with variation of growth rates (R) and thermal gradient((G), $32^{\circ}C$/cm, and 35$^{\circ}C$/cm. The lamellar structure was varied according to growth condition(G/R ratio). For the structure refinementthe effect of G/R was found out to be greater rather than that of vibration. The interlamellarspacing(l) in this materials was varied with the growth rates(R) by "$\lambda^{2}R$=Constant" relationshipquot; relationship

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.351-356
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• 1997

With the aid of advanced structural engineering, the construction of infrastructures has been recently accelerating to keep up with rapid economic growth. Construction activities and operation of transportation facilities cause civil petitions associated with vibration-induced damages or nuisances. As part of the decrease of vibration induced damage, the objective of this study is to develop vibration-controlled concrete with vibration-reduced materials, which can be recycled from obsolete materials, such as aged tires, plastics and etc. Appropriate mix proportion has been used for making 10 reinforced concrete panels with vibration-reduced materials, which have been tested to investigate on vibration reduction capability, based on the time and frequency domain analysis, and vibration velocity level analysis. Vibration-reduced mixtures are latex, styrofoam, rubber powder and plastic resin, which have been determined to by reduce vibration.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.1-6
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• 2010

Ball bearings are one of main components that support the rotational shaft in high speed rotary machinery. So, it is very important to detect the incipient faults and fault growth of bearing since the damage and failure of bearing can cause a critical failures or accidents of machinery system. In the past, many researchers mainly performed to detect the bearing fault using traditional method such as wavelet, statistics, envelope etc in vibration signals. But study on the detection technique for bearing fault growth has a little been performed. In this paper, we verified the possibility for monitoring of fault growth and detection of fault size in bearing outer-race by using the envelope powerspectrum and probabilistic density function from measured vibration signals.