• Journal of the Korea Furniture Society
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• v.10 no.1
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• pp.57-63
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• 1999

This study was carried out to analyze the relationship between basic physical properties and acoustical characteristics of imported violin wood and to offer the information on raw material procurement and incoming-material quality control to domestic violin makers which have purchased most raw materials from European exporting countries at high expense. Equilibrium moisture content of European spruce with lower specific gravity after the prolonged storage was rather higher than that of European maple with higher specific gravity. The specific gravity of spruce increased with decreasing annual ring width, however, that of narrower annual ring. Increasement in specific gravity enhanced the dynamic Young's modulus of both wood species, but influenced the vibration energy loss by internal friction differently between two species. For dynamic MOE, qurater-sawn spruce was higher than the flat-sawn, but maple showed the reverse directional characteristics. Consequently, it would be well for violin makers to establish the standard for materials and quality control system to assure the quality of their violin products.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.5
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• pp.91-99
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• 2010

The center of gravity on vehicle is a fundamentally important point for assessing and measuring the characteristics of vehicle dynamics. Especially, the center of gravity height on vehicles is the closest factor with respect to rollover accidents in a social issue nowadays. In this paper, the center of gravity height in conjunction with vehicle parameters of vehicle weight, driving axle and roof height after measured by vehicle weight and loading location by means of VCGM developed by KATRI with good performance that the accuracy was less than 0.6% and repeatability 0.3% for vehicles being used in the whole world was observed. As a result of study, the location of center of gravity height on vehicle was able to be estimated with only roof height on vehicle.

• Earthquakes and Structures
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• v.9 no.1
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• pp.111-126
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• 2015

In this study, the coupled effects of magnetic field, stress and thermal field on gravity waves propagating in a liquid layer over a solid surface are discussed. Due to change in temperature, initial hydrostatic stress and magnetic field, the gravity-sound Rayleigh waves can propagate in the liquid-solid interface. Dispersion properties of waves are derived by using classical dynamical theory of thermoelasticity. The phase velocity of gravity waves influenced quite remarkably in the presence of initial stress parameter, magneto-thermoelastic coupling parameter in the half space. Numerical solutions are also discussed for gravity-Rayleigh waves. In the absence of temperature, stress and magnetic field, the obtained results are in agreement with classical results.

• Advances in concrete construction
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• v.6 no.3
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• pp.269-283
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• 2018

This study presents the effects of geometrical dimensions of concrete gravity dams on the seismic response considering different base width/dam height (L/H) ratios. In the study, a concrete gravity dam with the height of 200 m is selected and finite element models of the dam are constituted including five different L/H ratios such as 0.25, 0.5, 0.75, 1.00, 1.25. All dams are modeled in ANSYS software considering dam-reservoir-foundation interaction. 1989 Loma Prieta earthquake records are applied to models in upstream-downstream direction and linear time history analyses are performed. Dynamic equilibrium equations of motions obtained from the finite element models of the coupled systems are solved by using Newmark time integration algorithm. The seismic response of the models is evaluated from analyses presenting natural frequencies, mode shapes, displacements and principal stresses. The results show that the L/H ratios considerably affect the seismic response of gravity dams. Also, the model where L/H ratio is 1.00 has more desirable results and most appropriate representation of the seismic response of gravity dams.

• International Journal of Aerospace System Engineering
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• v.7 no.1
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• pp.1-6
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• 2020

A deployment mechanism is designed to stow into a small volume efficiently. The panels are fabricated by carbon fiber reinforced plastics (CFRPs). The parameters for the deployment are determined by considering the number of panels, the folding/twisting angles, and the driving force for a deployment device. In addition, a surface accuracy of the manufactured reflector is measured through a photogrammetry methodology. The deployment behavior of CFRP reflector is observed by using the zero-gravity device which compensates the gravity effect during the deployment. The zero-gravity device is constructed wire, motor, controller and loadcell. During the deployment of the reflector panel, the wire and motor compensate for its weight by the feedback process of the controller. Tests result show that a zero-gravity device compensates for the weight of the panel during the deployment of the CFRP reflector.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.338-346
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• 2004

Experimental data on the effect of the variable gravity magnitude, namely microgravity, normal gravity and hyper-gravity, on flow pattern and frictional pressure drop were obtained during co-current air-water flow in a horizontal tube, The flow patterns were found to depend strongly on the gravity magnitude and certain flow pattern were found to depend on the gas superficial velocity. The effect of the gravity magnitude had an effect on the frictional pressure drop only at low flow rates. The present data are used to evaluate some of existing flow pattern transition and pressure drop models and correlations.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.35-37
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• 2010

To construct precision geoid model, the gravity data having equal distribution and quality is necessary. In previous study, however, the geoid model has low precision since the biased distributed gravity data and some unverified data has been used and the gap between land and ocean exists. Now, the airborne and land gravity data was collected by various survey and the ship-borne gravity data and altimeter data has been achieved. Therefore, the precision geoid model development would be possible. And the GPS/Leveling data obtained by NGII could be used for construction of hybrid geoid in Korea. In this study, the procedure of geoid construction based on airborne, land, ship-borne and altimeter data using Remove-Restore technique will be explained. And the verification of gravimetric geoid and hybrid geoid would be introduced.

• Journal of The Korean Astronomical Society
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• v.39 no.4
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• pp.125-128
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• 2006

In order to determine the precise effective temperature and surface gravity of warm stars, all synthetic spectral lines in the wavelength range of $4000-5700{\AA}$ with T=6000-7750 K, and log g=3.5, 4.0, and 4.5 for [M/H]=0.0, $V_{rot}$=10 km $s^{-1}$, and $V_{tubl}$=2 km $s^{-1}$ were calculated using the SYNSPEC package(Hubeny, et al., 1995) and the Kurucz(1995) model. Then, the depth-ratios for all line pairs were investigated and we selected two and six depth-ratios appropriate for the surface gravity and temperature indicators, respectively. We plotted six grids with X- and Y-axes for the depth-ratios of surface gravity and temperature, respectively, for the simultaneous estimation of these two atmospheric parameters. This method was applied to the spectum of $\delta$ Scu for the determination of its temperature and surface gravity simultaneously.

• Mycobiology
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• v.45 no.3
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• pp.226-231
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• 2017

Coprinopsis cinerea was employed to investigate the fungal response to gravity. Mycelium growth revealed a consistent growth pattern, irrespective of the direction of gravity (i.e., horizontal vs. perpendicular). However, the fruiting body grew in the direction opposite to that of gravity once the primordia had formed. For the proteomic analysis, only curved-stem samples were used. Fifty-one proteins were identified and classified into 13 groups according to function. The major functional groups were hydrolases and transferases (16%), signal transduction (15%), oxidoreductases and isomerases (11%), carbohydrate metabolism (9%), and transport (5%). To the best of our knowledge, this is the first report on a proteomic approach to evaluate the molecular response of C. cinerea to gravity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.511-516
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• 2004

The dynamic behavior of an automatic ball balancer (ABB) is studied considering the effects of gravity and angular velocity profiles. In this study, a physical model for an ABB installed on the Jeffcott rotor is adopted in order to investigate the effects of gravity and angular acceleration. The equations of motion for the rotor with ABB are derived by using Lagrange's equation. Based on derived equations, dynamic responses for the rotor are computed by using the generalized-o method. From the computed responses, the effects of gravity and angular velocity profiles on the dynamic behavior are investigated. It is found that the balancing of the rotor with ABB can be achieved regardless of gravity. It Is also shown that a smooth velocity profile yields relatively smaller vibration amplitude than a non-smooth velocity profile.