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

• Journal of environmental and Sanitary engineering
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• v.11 no.3
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• pp.29-35
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• 1996

Numerical solutions were obtained to the model equations for various parameters characterizing the pore structure, effective internal diffusion and the chemical reaction constant. The conversion was decreased with the cause of pore closure at the surface of reacting particles, reduction of porosity, surface area of reaction and effective diffusion coefficient in the solid with the progress of reaction. Total conversion was strongly depend on the local conversion at surface. According to the decreasing of impregnated concentration of the copper oxide and the increase of the flue gases concentration, total conversion was increased. And the conversion were affected by gas flow rate and pore size distribution of the reacting solid.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.361-366
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• 2005

Since most soils exist above the ground water table, negative pore pressure exist in unsaturated soils. Negative pore water pressure in unsaturated soil affects the soil structure and degree of saturation and it is important for accurate evaluation of unsaturate flow and behavior. This negative pore pressure is called a matric suction which causes an increased shear strength. Therefore, it is required that the effect of increase in the shear strength should be included in a geotechnical analysis. From the test result, the influence of net confining pressure and matric suction on the shear strength was analyzed and strength parameter was increased with matric suction increase and a unliner relationship was found to relate matric suction and shear strength.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1060-1067
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• 2009

Previous research on the slope failure has mainly reported that most of the slope failures occur due to surface rainfall infiltration in the rainy season. A slope of which surface is protected by shotcrete or plants, can also fail due to increase in pore water pressure from the ground water flow beneath the surface, rather than from the surface. In this study such case of slope behavior is investigated using the model test and numerical method including strength reduction method. Hydraulic boundary conditions of the slopes is considered using coupled numerical scheme. The failure mechanism of the slope is investigated and the effect of pore water pressure on slope safety is identified. Increase in pore water pressure due to lateral infiltration has significantly reduced the stability of slope.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.7
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• pp.448-453
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• 2010

Porous media containing complex fluid passage have especially large surface area per unit volume. This study is aimed to identify the heat transfer characteristics of high-porosity metal foams in a horizontal channel. Experiment is performed under various heat flux, velocity and pore density. Nusselt number decreases with higher pore density. Metal foams shows higher heat transfer coefficients than pin-fin structure with the same porosity. This is due to the more complex flow passage and larger heat transfer area based on the structure of the metal foams. The analysis on the pin-fin structure may not be suitable to the metal foam structure but should be identified extensively through further study.

• Geomechanics and Engineering
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• v.4 no.2
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• pp.91-103
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• 2012

Focusing on the effect of excess pore pressure dissipation on liquefaction-induced ground deformation, a series of 1-g shaking table tests were conducted in a rigid soil container by use of saturated Toyoura sand, the relative density of which was 20-60%. These tests were subjected to the sinusoidal base shaking with step increased accelerations: 100, 200, 300 and 400 Gals for 2-4 seconds. Shaking table tests were done using either water or polymer fluid with more viscous than water, thus varying the sand permeability of model tests. Excess pore pressures, accelerations, settlements and lateral deformations were measured in each test. Test results are presented in this paper and the effect of sand permeability on liquefaction and liquefaction-induced ground deformation was discussed in detail.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.2
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• pp.73-79
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• 2001

Experiment were carried out to investigate the heat transfer characteristics of an aluminum foam block as a porous heat sink on a heat source by a vertical air jet impingement that can be applied for electronics cooling. The performance of the aluminum foam heat sink was evaluated by the convective heat transfer coefficient on the heat source. At a fixed porosity, pore density ($\beta$) of the foam and Reynolds number Re were varied in the range of $\beta$a=10, 20, 40 PPI(Pore Per Inch) and $850\leqRe\leq25000$. A nozzle diameter and the nozzle-to-plate spacing were also varied. It was found that the convective heat transfer was enhanced by the aluminum foam heat sink with lower pore density due to relatively intensified flow through the foam block. The aluminum foam block with much reduced weight shows slightly better performance with larger Nusselt number, compared with the convectional heat sink.

• Membrane Journal
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• v.27 no.5
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• pp.406-414
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• 2017

In this study, we have developed pore-filled ion-exchange membranes (PFIEMs) filled with ionomer in a thin polyethylene porous film (thickness = $25{\mu}m$) and investigated the charge-discharge characteristics of the all vanadium redox flow battery (VRFB) employing them. Especially, the degree of crosslinking and free volume of the PFIEMs were appropriately controlled to produce ion-exchange membranes exhibiting both the low membrane resistance and low vanadium permeability by mixing crosslinking agents having different molecular size. As a result, the prepared PFIEMs exhibited excellent electrochemical properties which are comparable to those of the commercial membranes. Also, it was confirmed through the experiments of vanadium ion permeability and VRFB performance evaluation that the PFIEMs showed low vanadium ion permeability and high charge-discharge efficiency in comparison with the commercial membrane despite their thin film thickness.

• Journal of the Korean Society of Safety
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• v.28 no.5
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• pp.35-40
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• 2013

Recently reclamation land is largely developed to utilize the land according to economic growth. The soil of landfill is soft, low shear strength, which makes it difficult to use the equipment. A large movement is occurred on the utility tunnel under construction. The inclined land with high water level and underground facilities are widely distributed and the excess pore water pressure may occur under construction similarly to this study. Some different conditions are made to design result, such as 4m of soil piling near the construction area, heavy rainfall during 2nd excavation that may cause flow liquefaction. To analyze the cause of transverse lateral movement, Three dimensional analysis are performed to four load cases, which is original design condition, flow liquefaction by heavy rainfall, unsymmetric lateral soil pressure, and both of them simultaneously. Ten steps of full construction stage, 1st excavation for utility tunnel, construction of utility tunnel, 1st refill, piling soil from 1m to 4 m, 2nd excavation for drainage culvert, liquefaction around the utility tunnel, construction of drainage culvert and 2nd refill, are take into account to investigate the cause of movement.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.2 s.54
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• pp.81-94
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• 2007

In most experimental researches on the liquefaction phenomenon, an earthquake as a random vibration has been regraded as a sinusoidal wave or a triangular wave with an equivalent amplitude. Together with the development in the part of signal control and data acquisition, dynamic experimental equipments in the soil dynamics have also developed rapidly and further more, several real earthquakes have been simulated in the large model test such as shaking table tests and centrifuge tests. In Korea, several elementary laboratory tests to simulate the real earthquake load were performed. From these test results, it was reported that the sinusoidal wave cannot reliably reflect the soil dynamic behavior under the real earthquake motion. In this study, 4 types of dynamic motions such as the sinusoidal wave, the triangular wave, the incremental triangular wave and several real earthquake motions which were classified with shock-type and vibration-type were loaded to find something new to explain the change of the excess pore water pressure under the real earthquake load. Through the detailed investigation and comparison on all test results, it is found that the dynamic flow is generated by the soil plastic deformation and the velocity head of dynamic flow is changed the pressure head in the un-drained condition. It can be concluded that the change of the excess pore water pressure is related to the pressure head of dynamic flow. Lastly, a new hypothesis to explain such a liquefaction initiation phenomenon under the real earthquake load is also proposed and verified.