• Carbon letters
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• v.12 no.2
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• pp.112-115
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• 2011

The scope of this work investigates the relationship between the amount of oxygen-functional groups and hydrogen adsorption capacity with different concentrations of phosphoric acid. The amount of oxygen-functional groups of activated carbons (ACs) is characterized by X-ray photoelectron spectroscopy. The effects of chemical treatments on the pore structures of ACs are investigated by $N_2$/77 K adsorption isotherms. The hydrogen adsorption capacity is measured by $H_2$ isothermal adsorption at 298 K and 100 bar. In the results, the specific surface area and pore volume slightly decreased with the chemical treatments due to the pore collapsing behaviors, but the hydrogen storage capacity was increased by the oxygen-functional group characteristics of AC surfaces, resulting from enhanced electron acceptor-donor interaction at interfaces.

• Macromolecular Research
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• v.13 no.2
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• pp.107-113
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• 2005

We developed an algorithm to simulate the generation of virtual nanowebs using the Monte Carlo method. To evaluate the pore size of the simulated multi-layered nanoweb, an estimation algorithm was developed using a ghost particle having zero volume and mass. The penetration time of the ghost particle through the virtual nanoweb was dependent on the pore size. By using iterative ghost particle penetrations, we obtained reliable data for the evaluation of the pore size and distribution of the virtual nanowebs. The penetration time increased with increasing number of layers and area ratio, whereas it decreased with increasing fiber diameter. Dimensional analysis showed that the penetration time can be expressed as a function of the fiber diameter, area ratio and number of layers.

• 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.

• Bulletin of the Korean Chemical Society
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• v.26 no.7
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• pp.1075-1078
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• 2005

Hydrogen adsorption on various porous materials have been studied with a volumetric method at low temperature in the pressure of 0-760 torr. Their hydrogen uptakes depend at least partly on microporosity rather than total porosity. However, it is also necessary to consider other parameters such as pore size and pore architecture to explain the adsorption capacity. The heat of adsorption and adsorption-desorption-readsorption experiments show that the hydrogen adsorption over the porous materials are composed of physisorption with negligible contribution of chemisorption. Among the porous materials studied in this work, SAPO-34 has the highest adsorption capacity of 160 mL/g at 77 K and 1 atm probably due to high micropore surface area, micropore volume and narrow pore diameter.

• Journal of Environmental Science International
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• v.19 no.6
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• pp.681-687
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• 2010

Mesoporous silica was prepared from hydrothermal synthesis using gel mixture of tetraethylorthosilcate (TEOS) as silica source and cetyltrimethylammonium bromide (CTMABr) as a surfactant. In the optimum synthesis cause, molar ratio of template and silica changed. The surface and structure properties of mesoporous silica were determined by XRD, SEM, TEM and BET. Also, surface potential of mesoporous silica was measured using zeta potential. $N_2$ adsorption isotherm characteristics, including the specific surface area ($S_{BET}$), total pore volume $V_T$), and average pore diameter ($D_{BJH}$), were determined by BET. As a result, SBET of $100m^2/g{\sim}1500m^2/g$ was determined from the $N_2$ adsorption isotherm. Also, the average pore diameter was 2 nm∼4 nm. Mesoporous silica's surface potential of minus charge was determined from zeta potential.

• KSBB Journal
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• v.6 no.4
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• pp.425-429
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• 1991

Porous glasses were prepared from $TiO_2$ containing borosilicate glass by the phase separation. Pore distribution and surface area of porous glasses were invesigated by SEM and porosimeter. As temperature and heating time increase. The pore size and volume increased, but the specific surface area decreased above the critical temperature. The specific surface area and pore size showed more sensitive change on the variation of heating temperature than of heating time.

• Horticultural Science & Technology
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• v.19 no.2
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• pp.179-185
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• 2001

Throughout the world, physical and chemical analyses of horticultural substrates are carried out in many different ways at the different laboratories. In Europe, standardization in properties and analytical methods of horticultural substrates has been a topic over the last decades. As a result, the CEN methods as European standard methods for the physical and chemical analyses were introduced and the final draft was reported in 1999 by CEN(Committee for European Standardization). Dry matter and moisture content are analyzed after drying samples at $103^{\circ}C$. Laboratory compacted bulk density is analyzed by determining the weight of sample compacted in the test cylinder with constant volume. Dry bulk density, particle density, total pore space, water volume, air volume and volume shrinkage are determined by saturating, draining and drying the sample using double rings and a sand suction table. pH and EC are analyzed by 1:5(sample:distilled water) extraction method on the basis of volume. Organic matter and ash content are determined after drying and combusting the samples. Now, CEN methods are being regarded almost as European standard methods. Further study needs to be carried out for universal applicability of the CEN methods to all the substrates.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.393-400
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• 1996

The conducting polymer composites were prepared by imbibing the porous particle with an $FeCl_3$ oxidant solution, drying the imbibed porous particle, and imbibing again with pyrrole solution for polymerization to take place in the pore. The conductivity of the porous composite particles, was higher than that of nonporous particles. Also, the conductivity of composite was increased with increasing specific surface area and pore specific volume of the host porous particles since the degree of formation of conducting polymer in the pore increased.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.295-302
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• 2000

Earthquakes not only produce additional load on the structures and underlying soil, but also change the strength characteristics of the soil. Therefore, in order to analyze soil structures for stability, the behaviour after earthquake must be considered. In this paper, a series of cyclic triaxial tests and monotonic triaxial tests were carried out to investigate the undrained shear strength and liquefaction strength characteristics of Nak-Dong River sand soils which were subjected to cyclic loading. The sample was consolidated in the first stage and then subjected to stress controlled cyclic loading with 0.1Hz. After the cyclic loading, the cyclic-induced excess pore water pressure was dissipated by opening the drainage valve and the sample was reconsolidated to the initial effective mean principal stress(p/sub c/'). After reconsolidation, the monotonic loading or cyclic loading were applied to the specimen. In the results, the undrained shear strength and liquefaction strength characteristics depended on the pore pressure ratio(Ur=U/p/sub c/'). The volume change following reconsolidation can be a function of cyclic-induced excess pore water pressure and the maximum double amplitude of axial strain.

• Journal of environmental and Sanitary engineering
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• v.20 no.4 s.58
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• pp.45-50
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• 2005

Titania gel formations were prepared by sol-gel method using titanium(IV) chloride $(TiCl_4)$, and its characteristics were analyzed by varying the $epoxide/TiCl_4$ ratio and the amount of water In the end, titania $(TiO_2)$ aerogel were prepared using supercritical drying process. VOCs such as benzene, toluene, and m-xylene (BTX) were oxidized using prepared titania aerogel and commercially available $TiO_2$, and its performance was compared. The surface area, pore volume, and average pore diameter of 1,2-epoxybutane are significantly smaller than the propylene oxide. And the titania aerogels with 6 moi of epoxides have high surface areas, pore volumes, and average pore diameters. As a result of photo-oxidation, conversion of benzene was reached about $70\%$, and other reactants were reached about $60\%$ similarly. The conversion of BTX was increased as inlet concentration decreased. The reactivity of titania calcined at $600^{\circ}C$ was greater than $400^{\circ}C$ and $800^{\circ}C$. Water is required as a reactants for the oxidation of VOCs, and the continuous consumption of hydroxyl radicals required replenishments to maintain catalyst activity. The activity ratio increased with increasing reaction time when enough amount of water was present in the reactor.