• Computers and Concrete
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• v.11 no.4
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• pp.317-336
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• 2013

In this study, the pore structure of Portland cement paste is experimentally characterized by MIP (mercury intrusion porosimetry) and nitrogen adsorption, and simulated by a newly developed status-oriented computer model. Cement pastes with w/c=0.3, 0.4 and 0.5 at ages from 1 day to 120 days are comprehensively investigated. It is found that MIP cannot generate valid pore size distribution curves for cement paste. Nevertheless, nitrogen adsorption can give much more realistic pore size distribution curves of small capillary pores, and these curves follow the same distribution mode. While, large capillary pores can be effectively characterized by the newly developed computer model, and the validity of this model has been proved by BSE imaging plus image analysis. Based on the experimental findings and numerical simulation, a hypothesis is proposed to explain the formation mechanism of the capillary pore system, and the realistic representation of the pore structure of hydrated cement paste is established.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.90-97
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• 2003

The purpose of this study is to understand the dissipation pattern of excess pore pressure after liquefaction which governs the post-liquefaction behavior of liquefied sand deposits. 1-g shaking table tests were carried out on 5 different kinds of sands, all of which had high liquefaction potentials. During the tests excess pore pressure at various depths, and surface settlements were measured. The measured curve of the excess pore pressure dissipation was simulated using the solidification theory, and from the analysis of the velocity of dissipation, the dissipation pattern of excess pore pressure after liquefaction was examined. The dissipation velocity of excess pore pressure after liquefaction had a linear correlation with the effective grain size ( $D_{10}$) divided by the coefficient of uniformity ( $C_{u}$), and the increase in the initial relative density of the ground played a role in shifting this correlation curve toward an increased dissipation velocity. From the correlation, an approximate method was recommended for prediction of the dissipation curve of excess pore pressure after liquefaction in saturated sand deposits.s.s.

• Geomechanics and Engineering
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• v.17 no.2
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• pp.157-164
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• 2019

The effect of electrochemical modification of the physical and mechanical properties of sandstone from Paleozoic coal measure strata was investigated by means of liquid nitrogen physical adsorption, X-ray diffraction and uniaxial compressive strength (UCS) tests using purified water, 1 mol/L NaCl, 1 mol/L $CaCl_2$ and 1 mol/L $AlCl_3$ aqueous solution as electrolytes. Electrochemical corrosion of electrodes and wire leads occurred mainly in the anodic zone. After electrochemical modification, pore morphology showed little change in distribution, decrease in total pore specific surface area and volume, and increased average pore diameter. The total pore specific surface area in the anodic zone was greater than in the cathodic zone, but total pore volume was less. Mineralogical composition was unchanged by the modification. Changes in UCS were caused by a number of factors, including corrosion, weakening by aqueous solutions, and electrochemical cementation, and electrochemical cementation stronger than corrosion and weakening by aqueous solutions.

• Membrane and Water Treatment
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• v.13 no.4
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• pp.167-172
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• 2022

The analytical results are presented for the mass transfer in a cylindrical pore covering from the macroscale, multiscale to nanoscale owing to the variation of the inner diameter of the pore. When the thickness h_bf of the physically adsorbed layer potentially fully formed on the pore wall is comparable to but less than the inner radius R₀ of the pore, the multiscale flow occurs consisting of both the nanoscale non-continuum adsorbed layer flow and the macroscopic continuum liquid flow; When R₀ ≤ h_bf, the flow in the whole pore is essentially non-continuum; When R₀ is far greater than h_bf, the flow in the whole pore can be considered as macroscopic and continuum and the adsorbed layer effect is negligible.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.4
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• pp.7-13
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• 2007

Effects of pulp type, refining and filler type on the pore characteristics and physical properties of paper were investigated. HwBKP, SwBKP and BCTMP are used to study the effect of pulp type in this study. The effects of each filler (PCC, GCC and talc) and the combination of PCC/GCC were also studied. Highest bulk, pore volume and light scattering are obtained from BCTMP and PCC. It was found that the pore size and pore volume are important in light scattering in paper structure. It was found that PCC was the most effective filler for the improvement of the bulk and light scattering because of the increase in pore volume which can scatter light, but the increase of PCC content was not so effective in the improvement of bulk.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.617-620
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• 2011

Thermal shock behavior of porous ceramic nozzles with various pore sizes for continuous casting process of steel was investigated in terms of physical properties and microstucture. Porous nozzle samples with a composition of $Al_2O_3$-$SiO_2$-$ZrO_2$ were fabricatedby adding various sizes of graphite as the pore forming agent. As the graphite size increased from 45~75 to 150~180 ${\mu}m$, both the resulting pore size and the flexural strength also increased. A thermal shock test was carried out at temperatures (${\Delta}$T) of 600, 700, 800, and 900$^{\circ}C$. Microstructure analysis revealed a small number of cracks on the sample with the largest mean pore size of 22.32 ${\mu}m$. In addition, increasing the pore size led to a smaller decrease in both pressure drop and elastic modulus. In conclusion, controlling the pore size can enhance thermal shock behavior.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.4
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• pp.179-189
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• 1999

This study attempts to propose an evaluation considering the property of concrete pore which affects the deterioration of neutralization and the rebar resistance of concrete. Understanding pore property of concrete in using extent, for practical using of concrete manufacturing condition. basic quality property and durability estimation etc, the results of the experiment are as follows. 1) The result of analysis pore property of every specimen with the method of area ratio, in limitation of $10^{-6}{\sim}10^{-5}m$, the pore distribution ratio was maximum. It was high value as W/C was increased and the unit cement content was decreased. 2) In case of using admixture. the volume of pores was some increased as variation of mixing content. In high W/C range, it was very increased compared with plain concrete. 3) Concerned with compressive strength and volume of pores in hardened concrete, it is possible compressive strength estimation using the property of concrete pores. 4) Direct measurement of concrete pore property is difficult. the valuation of the dynamic modulus of elasticity using ultrasonic wave velocity was available. 5) Quantitatively evaluation of concrete structure durability by past result of pore distribution estimation, and it can be estimative scale of property study on the concrete materials.

• Membrane Journal
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• v.17 no.4
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• pp.329-337
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• 2007

This is the research about a new method to make the internal separation layer with smallest pore size in polyethersulfone (PES) membrane by adding p-toluenesulfonic acid (TSA) and polyvinylpyrolidone (PVP) to polymeric PES solution. The preparation and morphological characterization of PES sheet membranes containing PVP as a hydrophilic swelling material and TSA as a demixing material were performed. As a result by microflow porometery, the PVP and TSA added PES membranes showed good permeabilities and narrow pore size distributions, comparable to those of the commercial membranes. The concentration of PVP affected the PES characteristics on air permeability and surface structure. The concentration of TSA influenced on pore size distribution but do not affect air permeability. The surface images of FE-SEM shows similar pore size when TSA added or not. However, the cross-section images of FE-SEM show that the TSA added PES membranes have a increase of internal layer thickness with smallest pore size.

• Geotechnical Engineering
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• v.8 no.2
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• pp.59-70
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• 1992

This work is to study experimentally the measurment of pore air pressure according to rainfall in colluvium model and the characteristics of pore water pressure according to increasement of artesian ground water head. After modeling a geological feature of the Tertiary formation, the experiment was performed about sixty times on three kinds of soil. This experimental results showed the variation of pore water and pore air pressures with time, the change of void ratio and appling pressure head in the nonsaturated soil. It can be also expressed by the final pore water and the air reaction ratios and then formularizing the relationship between the permeability coefficient and the void ratio. In the results of this experiment, the patterns of the pore water pressure reaction are classified by the step-type and the wave-type, and the time-lag to reach final point of pore water pressure is in order sand, sandy silt and clayey sand.

• Geomechanics and Engineering
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• v.35 no.6
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• pp.627-636
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• 2023

The essence of subgrade mud pumping under train load is the migration of fine particles in subgrade soil. The migration of fine particles will change the pore structure of overlying ballast, thus affecting the mechanical properties and hydraulic properties of ballast layer. It is of great theoretical significance and engineering value to study the effect of fine particle migration on the pore structure of ballast layer under cyclic loading. In this paper, a tailor-made subgrade mud pumping test model and an X-ray computed tomography (CT) scanning equipment were used to study the influence of migration of fine particles in subgrade soil on the pore parameters (plane porosity, volume porosity, pore distribution and pore connectivity) of overlying ballast under cyclic loading. The results show that the compression of ballast pores and the blockage of migrated fine particles make the porosity of ballast layer decreases gradually. And the percentage of small pores in ballast layer increases, while the percentage of large pores decreases; the connectivity of pores also gradually decreases. Based on the test results, an empirical model of ballast porosity evolution under cyclic loading is established and verified.