• Membrane and Water Treatment
• /
• v.8 no.6
• /
• pp.553-562
• /
• 2017

In the present study, the water desalination across the penta-graphene has been explored by using molecular dynamics simulation. The penta-graphene, a new carbon allotrope, introduced theoretically in 2015. It was shown that this carbon nanostructure is slightly stiffer against buckling in comparison with the graphene nanoribbons. The effect of radius of curvature (ROC) of the membrane, pore size, and applied pressure, on water flow rate, and salt rejection is investigated. It is shown that salt rejection, and the shape of the oxygen density distribution inside the pore can be influenced by the ROC of membrane. Finally, it is shown that the ROC, and pore size of 2D membranes, play an important role in the salt rejection.

• Transactions of Materials Processing
• /
• v.15 no.2 s.83
• /
• pp.126-131
• /
• 2006

Metallic sandwich plates are ultra-light materials not only with high strength and stiffness but also with other multifunctional physical properties. Inner dimpled shell structure can be fabricated by a piecewise sectional forming process, and then bonded with face sheets of the same material by resistance welding. Possible region for bending and limit radius of curvature are defined to compare the formability of sandwich plates. Tests have shown that sandwich plates with inner dimpled shell structure subject to bending have longer possible region for bending and smaller limit radius of curvature than other types of sandwich plates. The proposed inner dimpled shell structure is shown to have better formability of sandwich plates for bending than other types inner structures.

• 한국연소학회:학술대회논문집
• /
• 1998.10a
• /
• pp.91-101
• /
• 1998

The effect of secondary flow on both methane/air and propane/air premixed flame was investigated experimentally. By changing the radius of curvature, various flame behavior was observed. In the V-bend nozzles, flame surface is deformed from axisymmetry. As the exit velocity increased, flame lifted off partially. When the radius of curvature of the V-bend increased, the region where premixed flame is entirely on the rim increased. Since the axial velocity field is changed due to the secondary flow effect, comparison of V-bend and straight tube with the same diameter shows larger V-bend nozzle exit velocity for both flash back and flame blowout. The flame characteristics are mapped with a equivalence ratio, a velocity, and a nozzle radius of curvature. To identify physical reasoning on the flame surface deformation, numerical calculations are conducted. OH radical distributions in flames are visualized by PLIF technique.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.12
• /
• pp.173-179
• /
• 1995

This paper descrived housing design in conception of dynamic characteristics. The vibration and noise in power train system of automobile are important on the environment matter. The vibration caused by meshing teeth of gear is transmitted to the gear box faces through shafts and bearings. Shape of housing is used different radius of curvature(R=0 to 80 mm). The velocity responese, sound power and radiation efficency on the surface of gear box are calculated. The sound power and radiation efficency are compared with different radius of curvature.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.13 no.6
• /
• pp.34-40
• /
• 2004

This paper presents studies on curvature radius measurement using the laser interferometer. It is a general practice to measure to $10^{-10}$m in length with the recent improvement and innovations in measurement technology and the processor used. The measurement methods can generally be categorized as these two: the contactual method and non-contactual method; and in this study, we will find ways to lower the cost for a CMM, or a coordinate measurement machine, and try to find an alternative. Furthermore, we will discuss some of the ways to improve the non-contactual measurement methods-optical interferometer method and the optical triangulation method. We will measure an object using a laser distance measuring device and Set the Point-contact result with the ball-bearing type and line-contact result with the bearing type, to decide on which probe type will be used.

• Journal of the Korea society of information convergence
• /
• v.6 no.1
• /
• pp.37-41
• /
• 2013

In this study, by using the Oculus Pentacam, we analyzed the relationship of corneal front astigmatism corneal and the radius of curvature of the rear face of the 20's to 40's. The vertical radius of curvature were man 7.94mm (${\pm}0.22$), women 7.87mm (${\pm}0.21$), the horizontal radius of the anterior corneal appeared man 7.69mm (${\pm}0.27$), women 7.63mm(${\pm}0.23$). And rear vertical radius of curvature were man 6.52mm(${\pm}0.23$), woman 6.55mm (${\pm}0.22$), the horizontal radius of the anterior corneal appeared man 6.06mm (${\pm}0.24$), woman 6.08mm(${\pm}0.24$). The results of correlation analysis between the radius of corneal posterior surface and the anterior corneal surface, it was found out that there is a significant correlation. In this study, similar results were obtained anterior surface of the cornea, the radius of curvature of the rear surface, the refractive power, and astigmatism, as other papers that have been reported. But in this paper, the cornea thickness was thicker than other previously reported paper.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.2961-2966
• /
• 2007

When the pressure at the weak spot established at a certain part of a high pressure vessel or piping system exceeds a design pressure, this weak spot is burst, and the pressurized gas emitted through the weak spot will cause a compression wave system. In this connection, in the present study, an experimental study by using a conventional shock tube facility is performed to estimate the effects of the material of diaphragm, curvature radius and thickness of materials on the valve opening time in diaphragm. Pressure sensor having 500kHz in natural frequency is installed at 35mm downstream of the rupture diaphragm to measure the static pressure history of propagating and being accumulated compression wave. 4 kinds of materials are used as diaphragm that is aluminium, copper, stainless steel and zinc. The diaphragm radii of curvature R are ${\infty}$, 120mm and 60, respectively. And the depth for $90^{\circ}$ groove is 0.04mm. It is found that the smaller the tensile strength and elongation of the rupture diaphragm is, the smaller the radius of curvature of the rupture diaphragm is, and for the same conditions the thinner the thickness of the rupture diaphragm is, the shorter the valve opening time becomes. Also, the tensile strength, elongation and the radius of curvature of the rupture diaphragm for the same conditions are smaller, the maximum pressure rise caused by the coalescences of the compression wave is smaller. Finally the pressure ratio is higher, the valve opening time is shortened and gradient of pressure increment is more steepen.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.1
• /
• pp.67-73
• /
• 2017

This study has addressed to evaluate the effects of radius of curvature and skew angle on the negative reaction in a plate girder bridge with LRB (Lead Rubber Bearing) supports. As analytical parameters, various radius of curvatures and skew angles were selected and two seismic loads of El-Centro and artificial earthquakes were applied to the bridge in the longitudinal and transverse directions. As results of 3D analysis, the possibility of negative reaction is shown at the part of acute angle and inner side of the curved bridge, and becomes increased when seismic load is applied in the transverse direction. In addition, the occurrence of negative reaction is found to be increased as both radius of curvature and skew angle decrease, which means that curved bridge has higher possibility of negative reaction than straight one. Conclusively, all of earthquake wave, gradient, radius of curvature and skew angle should be considered together to investigate the possibility of negative reaction at the bridge support subject to seismic load.

• Journal of Biosystems Engineering
• /
• v.13 no.2
• /
• pp.18-27
• /
• 1988

The basic model of impeller was developed for the theoretical analysis of performance. The developed model was tested with two different blade radius of curvature based on the pumping efficiency under the operating conditions in Korea. And the pump performance of the impeller was also tested for the various speeds. The results obtained are summarized as follows; 1. There was no significant effect on the different blade radius of curvatures on the discharge and pump efficiency. 2. Head and power requirement was increased in proportion to the blade radius of curvature. 3. In the mathematical approach of the blade radius of curvature, the method of involute curve was more recommendable as compared with the method of circular arc curve. 4. The pump efficiency of the model impeller developed based on the theoretical analysis increased about 10% more than that of the existing impeller.

• Journal of Energy Engineering
• /
• v.22 no.2
• /
• pp.105-111
• /
• 2013

The present study has been carried out to reduce the heat loss from a built in refrigerator by using reverse heat loss method to discern the region with larger heat loss. To perform this purpose, an infrared thermographic camera has been used to measure the surface temperature of the refrigerator and tried to improve the heat loss near the ice dispenser. The numerical heat transfer analysis also has been accomplished to clarify the heat transfer mechanism near the ice dispenser. The possible applicable method to reduce heat loss was increasing the curvature radius at the ice dispenser corner. The curvature radius has been changed from 0mm to 40mm to see the effect of the curvature at the corner. From the present research, the optimal curvature radius for the reduction of heat loss at the ice dispenser could be 30mm.