• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3711-3718
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• 2012

Here, we report a chain-length dependent morphology and pore structure tailing of mesoporous silica templated from organogels, which is formed by primary alkylamine and ethylene glycol at room temperature. As the chain length of alkylamine changes from 12 to 18, the resulted materials exhibit a morphology change from layers to spheres and platelets, respectively. SEM and TEM observation revealed that these shapes appear to be inherited from their parent organogels. Further pore structure characterization by nitrogen sorption analysis demonstrates that all the resulted silicas exhibit typical IV isotherms indicative of uniform mesopores, and their pore sizes are dependent on the chain length of alkylamine used.

• Korean Journal of Environmental Biology
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• v.36 no.3
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• pp.319-328
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• 2018

The morphology, anatomy and reproduction (tetra/bisporic and male) of Lithothamnion japonicum Foslie was studied, using holotype material and materials collected from Korea. Lithothamnion japonicum is characterized based on the presence of encrusting, warty to fruticose thallus, branched or unbranched short and cylindrical protuberances, conical shaped spermatangial conceptacles, branched (dendroid) spermatangial systems formed on floor, walls, and roof of conceptacle chamber, cylindrical shaped spermatangial conceptacle canal, 9-10 cell layered spermatangial conceptacle roof, raised tetra/bisporangial conceptacles without rims, flattened tetra/bisporangial conceptacle pore plate, 16-50 pores on each pore plate, 6-8 rosette cells surrounded by each pore, pore canal lining filaments composed of tetra/bisporangial conceptacle roof, and buried senescent tetra/bisporangial conceptacles completely infilled with relatively large and irregularly arranged calcified sterile cells. In this study, we report a new record of Lithothamnion japonicum from Korean coasts.

• Membrane Journal
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• v.21 no.4
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• pp.377-388
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• 2011

Flat sheet microfiltration membranes were prepared with polysulfone (PSF), polyethersulfone (PES), and polyphenylsulfone (PPS) by an immersion precipitation phase inversion method. In this method, dimethyl formamide (DMF) and polyvinylpyrrolidone (PVP) were used as a solvent and a wetting polymer additive, respectively. 2-butoxyethanol (BE) was used as a nonsolvent additive catalyst to form pore. The morphology of membranes was investigated by scanning electron microscopy and micropermporometer. The permeability of the membranes was evaluated with the flux of pure water. When the BE was added, the pore size of membranes became larger than blank membranes. The changes in the morphology of membrane due to the BE addition depend on polymer structure. All membranes have similar mean pore size and porosity. The mean pore sizes of PSF, PES, and PPS membranes were 0.282, 0.330 $0.308{\mu}m$, respectively. The porosities of PSF, PES and PPS membranes were 68.5, 66.1, 66.4%, respectively. However, the PPS membrane showed higher pore density on surface and narrower pore size distribution than PSF or PES membrane does. As a result, the pure water flux of PPS membrane ($357L/m^2\;hr$) was higher than that of PSF ($196L/m^2\;hr$) or PES membrane ($214L/m^2\;hr$).

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.5
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• pp.434-441
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• 2018

The pore size of nickel (Ni) bottom electrode layer (BEL) for low-temperature solid oxide fuel cells embedded with ultrathin-film electrolyte was controlled by changing the substrate surface morphology and deposition process parameters. For ~150-nm-thick Ni BEL, the upper side of an anodic aluminum oxide (AAO) substrate with ~65-nm-sized pores provided ~1.7 times smaller pore size than the lower side of the AAO substrate. For ~100-nm-thick Ni BEL, the AAO substrate with ~45-nm-sized pores provided ~2.6 times smaller pore size than the AAO substrate with ~95-nm-sized pores, and the deposition pressure of ~4 mTorr provided ~1.3 times smaller pore size than that of ~48 mTorr. On the AAO substrate with ~65-nm-sized pores, the Ni BEL deposited for 400 seconds had ~2 times smaller pore size than the Ni BEL deposited for 100 seconds.

• Journal of the Korean Ceramic Society
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• v.36 no.8
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• pp.813-819
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• 1999

Inner crack-like pores with controlled amount of Ca impurity level in the high purity alumina single crystal sapphire had been created by micro-fabrication technique which includes ion implantation photo-lithography Ar ion milling and hot press technique. The morphological change and the healing of crack-like pore in the Ca doped high purity single crystal alumina during high temperature heat treatment in vacuum were observed using optical microscopy. The hexagonal bridging ligaments were developed and the size of hexagonal bridging ligaments had been increased with temperature and Ca amount and had grown to their corner rounded. It appeared that the hexagonal bridging ligaments would have an equilbrium size with temperature and the amount of Ca addition. Three kinds of crack-like pore healing type were observed. Edge regression and ligament growth were observed from relatively low temperature in the crack-like pore. Edge regression were found in almost all of the crack-like pore but the ligament growth were found only in the several crack-like pores accelerating heating very fast. Flow type healing was observed above $1800^{\circ}C$ and It healed the crack-like pore very slowly.

• Journal of the Korean Ceramic Society
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• v.32 no.4
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• pp.462-470
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• 1995

The characteristics of spray-dried granules are important for dry pressing operation since they have great influences on die-filling, compaction ratio, and resulting green microstructure. An attempt was made to control granule morphology and the packing structure of fine Si3N4 particles in granules by adjusting suspension property. Mercury porosimetry was used to characterize the pore structures of both granules and green compacts. Finally, the effects of particle packing structure in granules and green microstructure on sintering behavior were investigated.

• Particle and aerosol research
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• v.12 no.3
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• pp.65-72
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• 2016

Nanoporous $SiO_2$ particles containing different pore volume and size were prepared from silicic acid by a spray pyrolysis. The pore size, pore volume and particle size could be controlled with varying the precursor concentration, reaction temperature, and amount of organic templates such as Urea and poly ethylene glycol (PEG). The pore size distribution, pore volume and specific surface area of as-prepared particles were analyzed by BET and BJH methods, and the average particle sizes were measured by a laser diffraction method. The nanoporous $SiO_2$ particles ranged $0.6-0.9{\mu}m$ in diameter were successfully synthesized and the average particle size increased as the silicic acid concentration increased. The morphology of nanoporous $SiO_2$ particles was spherical and pores ranged 1 - 40 nm in diameter were measured in the particles. In case of Urea added into silicic acid, it showed no much difference in the morphology, pore size and pore volume at different Urea concentration. On the other hand, when PEG was added, it was clearly observed that pore diameter and pore volume of the particles surface increased with respect to PEG concentration.

• Macromolecular Research
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• v.15 no.1
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• pp.65-73
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• 2007

Chitosan, fibroin, and hydroxyapatite are natural biopolymers and bioceramics that are biocompatible, biodegradable, and resorb able for biomedical applications. The highly porous, chitosan-based, bioceramic hybrid composite, chitosanlfibroin-hydroxyapatite composite, was prepared by a novel method using thermally induced phase separation. The composite had a porosity of more than 94% and exhibited two continuous and different morphologies: an irregularly isotropic pore structure on the surface and a regularly anisotropic multilayered structure in the interior. In addition, the composite was composed of an interconnected open pore structure with a pore size below a few hundred microns. The chemical composition, pore morphology, microstructure, fluid absorptivity, protein permeability, and mechanical strength were investigated according to the composition rate of bioceramics to biopolymers for use in tissue engineering. The incorporation of hydroxyapatite improved the fluid absorptivity, protein permeability, and tenacity of the composite while maintaining high porosity and a suitable microstructure.

• Journal of the Korean Ceramic Society
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• v.43 no.9 s.292
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• pp.564-568
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• 2006

AlO(OH) nano gel is used in precursor of ceramic material, coating material and catalyst. For use of these, not only physiochemical control for particle morphology, pore characteristic and peptization but also studies of synthetic method for preparation of advanced application products were required. In this study, AlO(OH) nano gel was prepared through the aging and drying process of aluminum hydroxides gel precipitated by the hydrolysis reaction of dilute NaOH solution and aluminum sulfate solution. In this process, optimum synthetic condition of AlO(OH) nano gel having excellent pore volume as studying the effect of water and aluminum sulfate mole ratio on gel precipitates has been studied. Water and aluminum sulfate mole ratio brought about numerous changes on crystal morphology, surface area, pore volume and pore size. Physiochemical properties were investigated as using XRD, TEM, TG/DTA, FT-IR, and $N_2$ BET method.

• Fibers and Polymers
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• v.6 no.2
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• pp.121-126
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• 2005

Semicrystalline poly(ethylene terephthalate) (cPET)/amorphous poly(ethylene terephthalate) with isophthalic acid (aPET) blends with 100/0, 75/25, 50/50, 25/75, and 0/100 by weight ratios were dissolved in a mixture of trifluoroacetic acid (TFA)/methylene chloride (MC) (50/50, v/v) and electrospun via the electrospinning technique. Solution properties such as solution viscosity, surface tension and electric conductivity were determined. The solution viscosity slightly decreased as aPET content increased, while there was no difference in surface tension with respect to aPET composition. The characteristics of the electro spun cPET/aPET blend nonwovens were investigated in terms of their morphology, pore size and gas permeability. All these measurements were carried out before and after heat treatment for various blend weight ratios. The average diameter of the fibers decreased with increasing aPET composition due to the decrease in viscosity. Also, the morphology of the electrospun cPET/aPET blend nonwovens was changed by heat treatment. The pore size and pore size distribution varied greatly from a few nanometers to a few microns. The gas permeability after heat treatment was lower than that before heat treatment because of the change of the morphology.