• Clean Technology
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• v.21 no.4
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• pp.241-247
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• 2015

Oyster shells are a waste product from mariculture that creates a major disposal problem in coastal regions of southeast Korea. To make practical use of unused oyster shells, calcined oyster shell (COS) collected from a local company was allowed to adsorb AITC (allyl isothiocyanate), and then tested the powder's ability to inhibit the growth of some potential food borne disease-causing bacteria. COS powder showed bacteriostatic effect that inhibited cell growth of Escherichia coli, Staphylococcus aureus and Salmonella typhimurium from 3 to 5 log10 CFU/mL at concentrations around 1%. The MIC of pure AITC was found as 1 mg/mL, 0.8 mg/mL and 0.7 mg/mL for Escherichia coli, Staphylococcus aureus and Salmonella typhimurium, respectively. The calcined powder adsorbed about 225 mg of AITC per gram of shell, indicating porous material was created by calcination. FTIR data confirmed the adsorption of AITC by COS. Characterization of particle data showed very fine particle size and highly convoluted surface. AITC adsorbed calcined oyster shell (ACOS) completely inhibited bacterial cell at 1% concentration. ACOS showed better antibacterial effect than COS, indicating synergistic effect of AITC and calcined oyster shell powder on bacteria.

• Polymer(Korea)
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• v.39 no.2
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• pp.323-328
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• 2015

Poly(${\varepsilon}$-caprolactone) (PCL) nanofibers and PCL/silica membranes were synthesized by sol-gel derived electrospinning and casting, respectively. Smooth PCL nanofibers were obtained from the precursor containing N,N-dimethylformamide (DMF). PCL/silica membranes were prepared by varying the tetraethyl orthosilicate (TEOS) contents from 0 to 40 vol% to investigate the effect of silica addition on mechanical properties and cytotoxicity of the membranes. Although the strength of the membranes decreased from 12 to 8 MPa with increasing the silica content, the strength remained almost constant 7 weeks after dipping in phosphate buffered saline solution (PBS). The strength reduction was attributed to the presence of a patterned surface pores and micro-pores present in the walls between pores. The crystal structure of the membranes was orthorhombic and the crystallite size decreased from 57 to 18 nm with increasing the silica content. From the agar overlay test, the PCL/silica membranes exhibited neither deformation and discoloration nor lysis of L-929 fibroblast cells.

• Korean journal of food and cookery science
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• v.29 no.2
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• pp.137-146
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• 2013

Premature-green wheat is typically obtained by early harvest when culms of wheat still appear green in color, and the wheat and its food products have been considered as wellbeing foods. The pasting properties of prematured whole green wheat powder (WGWP), were analyzed with a rapid viscosity analyzer (RVA), and compared with commercial flours. The RVA values of lower peak viscosity and time, holding strength, final viscosity, as well as breakdown and setback viscosity showed that the WGWP could retard a gelatination of starch and also delay retrogradation in bakery products. WGWP with different levels of 10, 20, 30 or 50% was added into flours for preparing bakery product (bread, muffin and cookie), and their quality properties were evaluated. The addition of WGWP lead to a reduction in loaf volume of bread and muffin, and bakery products containing different levels of WGWP showed the changed internal surface structure (e.g. pore size) observed with a scanning electron microscope when compared with the control (0% WGWP). The hardness, gumminess, chewiness of bread and muffins were increased, and cohesiveness was decreased as the WGWP content increased, but the hardness of cookies was decreased. The bakery products added WGWP showed darker and more greenish and yellowish color than control (p<0.05). The sensory evaluation showed that bakeries with WGWP were scored to have more greenish taste and green color (p<0.05), and muffins and cookies with WGWP were evaluated to have more nutty and less oily taste (p<0.05).

• Membrane Journal
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• v.25 no.2
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• pp.123-131
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• 2015

The PTMSP/PDMS graft copolymer were synthesized from the PTMSP[poly(1-trimethylsilyl-1-propyne)] and the PDMS[poly(dimethylsiloxane)] and then the PTMSP/PDMS-borosilicate composite membranes were prepared by adding the porous borosilicates to the PTMSP/PDMS graft copolymer. The number-average molecular weight (${\bar{M}}_n$) and the weight-average molecular weight (${\bar{M}}_w$) of PTMSP/PDMS graft copolymer were 460,000 and 570,000 respectively, and glass transition temperature ($T_g$) of PTMSP/PDMS graft copolymer appeared at $33.53^{\circ}C$ according to DSC analysis. According to the TGA measurements, the addition of borosilicate to the PTMSP/PDMS graft copolymer leaded the decreased weight loss and the completed weight loss temperature went down. SEM observation showed that borosilicate was dispersed in the PTMSP/PDMS-borosilicate composite membranes with the size of $1{\sim}5{\mu}m$. Gas permeation experiment indicated that the addition of borosilicate to PTMSP/PDMS graft copolymer resulted in the increase in free volume, cavity and porosity resulting in the gradual shift of the mechanism of the gas permeation from solution diffusion to molecular sieving surface diffusion, and Knudsen diffusion. Consequently, the permeability of $H_2$ and $N_2$ increased and selectivity ($H_2/N_2$) decreased as the contents of borosilicate increased.

• Membrane Journal
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• v.22 no.5
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• pp.359-368
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• 2012

For hybrid water treatment of high turbidity water, we used the hybrid module that was composed of photocatalyst packing between tubular membrane outside and module inside. Photocatalyst was PP (polypropylene) bead coated with $TiO_2$ powder by CVD (chemical vapor deposition) process. Water back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling for modified solution was prepared with humic acid and kaolin. Resistance of membrane fouling ($R_f$) decreased as humic acid concentration changed from 10 mg/L to 2 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L, which was the same with the previous results. Then, treatment efficiencies of turbidity and humic acid were above 98.9% and 88.7%, respectively. As results of treatment portions of UF, UF + $TiO_2$, and UF + $TiO_2$ + UV processes, turbidity was treated little by photocatalyst adsorption, and photo-oxidation. However, treatment portions of humic acid by adsorption and photo-oxidation were 2.5% and 12.3%, respectively. Compared with the previous results, treatment portions of humic acid by adsorption and photo-oxidation were different depending on membrane material and pore size. As simplified the process, the membrane fouling resistance after 180 minutes' operation ($R_{f,180}$) increased and the final permeate flux decreased a little.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.425-430
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• 2015

ZSM-5 crystals grew by hydrothermal synthesis method on the surface of foam type porous silicon carbide ceramics which fabricated by polymer replica method. Oxide layer was developed on the surface of the porous silicon carbide ceramics to induce growth of ZSM-5 from the surface. In this study, hydrothermal synthesis was carried out for 7 h at $150^{\circ}C$ using TEOS, $Al(NO_3){\cdot}9H_2O$ and TPAOH as raw materials in the presence of the porous silicon carbide ceramics. X-ray Powder Diffraction (XRD) and Scanning Electron Microscope (SEM) analyses were confirmed $1{\sim}3{\mu}m$ sized ZSM-5 crystals have grown on the surface of porous silicon carbide ceramics. BET data shows that small pores about $10{\AA}$ size drastically enhanced and surface area increased from $0.83m^2/g$ to $30.75m^2/g$ after ZSM-5 synthesis on the surface of foam type porous silicon carbide ceramics.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.4
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• pp.176-181
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• 2003

Rapid densification of a SiC powder with additive 0.5 wt% $B_4$C was conducted by spark plasma sintering (SPS). The unique features of the process are the possibilities of using very fast heating rate and short holding time to obtain fully dense materials. The heating rate and applied pressure were kept to be $100^{\circ}C$/min and 40 MPa, while sintering temperature and soaking time varied to 1800, 1850, 1900 and $1950^{\circ}C$ and 10, 20 and 30 min, respectively. All of the SPS-sintered specimens at $1950^{\circ}C$ reached near-theoretical density. The XRD found that 3C-to-6H transformation at $1850^{\circ}C$. The microstructures of the rapidly densified SiC ceramics consisted of duplex microstructure with ultrafine equiaxed grains under 2 $\mu\textrm{m}$ and elongated grains of 0.5∼2 $\mu\textrm{m}$ wide, length 3∼10 $\mu\textrm{m}$. The biaxial strength increased with the increase of sintering time. Strength of 392.7 MPa was obtained with the fully densified specimen sintered at $1950^{\circ}C$ for 30 min, in agreement with the general tendency that strength increases with decreases pore. On the other hand, the fracture toughness shows the value of 2.17∼2.34 MPa$.$$m^{1/2}$ which might be due to the transgranular fracture mode.

• The Korean Journal of Zoology
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• v.32 no.2
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• pp.107-119
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• 1989

The histochemical characteristics of the cutaneous granular glands and its fine structure of the Korean fire bellied toad, Bombino orientalis Boulenger the only species inhabitated in Korea, were studied with light and electron microscopes. By the granular size and histochemical properties, the granular glands were subdivided into two types. The type I glands have small secretory granules (3.6 $\mu$ m), whereas the type II glands contain relatively larger granules (7.5 $\mu$ m). These two types of glands were simple alveolar gland, and they were commonly composed of inner glandular epithelial cells and outermost myoepithelial cells. By the histochemical reactions, these two secretory granules were not responsed to Alcian blue, but weakly positive reaction was observed in type I granular glands by the PAS reaction. And by the scanning electron microscopic observation, extemal morphology of the opening site of the gland duct was resembled to the stomata of the plant leaves. Especially the epithelial cells of the type I glands had fine reticular surface whereas, type II glands had large vesicular surface. These types of the glands conimonly had larger cavities than those of mucous glands, and forming the multinucleated unicellulr structure (syncytium) at the glandular epithelial layers. Secretory granules of these glands were originated from the rough endoplasmic reticulum of the glandular epithelial cells, and by the maturation level of the granule, morphological diversities appeared.

• Food Science and Preservation
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• v.15 no.1
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• pp.37-42
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• 2008

This study investigated the effects of green tea powder (GTP) on the quality characteristics of Yukwa during storage, to improve shelf-stability and sensory quality. The crude lipid contents of Yukwa decreased with increasing levels of GTP, but significant changes in moisture contents were not found. 'The blowhole size and expansion rate of Yukwa decreased with increases in GTP. The hardness of Yukwa samples with over 2% (w/v) GTP significantly increased, but no notable changes in hardness during storage were found. Sensory evaluation tests indicated that all sensory characteristics decreased with increasing GTP levels, but there was no significant difference in overall acceptability between Yukwa samples with 1% (w/v) GTP and control. Antioxidant activity increased as the concentration of GTP increased 'The results indicate that addition of 1% (w/v) G1P yielded optimal quality of Yukwa during storage.

• Membrane Journal
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• v.27 no.6
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• pp.487-498
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• 2017

In this study, pervaporation performances of water/methanol and water/butanol mixture were evaluated using zeolite 4A membranes manufacutred by FINETECH by experimental works and numerical modeling. Permeation and separation characteristics, such as flux and separation factor, were analyzed by gas chromatography (TCD) and liquid nitrogen traps. Experiments have shown that water is selectively separated from a mixture of water and methanol (separation factor up to approximately 250) and water and butanol (separation factor up to approximately 1,500). Generalized Maxwell Stefan (GMS) theory was implemented to predict pervaporation behaviors of water/alcohol mixtures and diffusional coefficients of zeolite layer were obtained through parameter estimation using $MATLAB^{(R)}$ optimization toolbox. Since the pore size of zeolite 4A are much larger than kinetic diameter of water molecules and smaller than those of methanol and butanol, zeolite 4A membranes can be applied to in situ water removal process such as membrane reactors or hybrid reaction-dehydration process.