• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.740-745
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• 2015

This study investigated the effect of different collection methods on physical properties of pectin hydrogels in microfluidic synthetic approach. The pectin hydrogels were simply produced by the incorporation of calcium ions dissolved in continuous mineral oil. Then, different collection methods, pipetting, tubing, and settling, for harvesting pectin hydrogels were applied. The settling method showed most uniform and monodispersed hydrogels. In the case of settling, a coefficient of variation was 3.46 which was lower than pipetting method (18.60) and tubing method (14.76). Under the settling method, we could control the size of hydrogels, ranging from $30{\mu}m$ to $180{\mu}m$, by simple manipulation of the viscosity of pectin and volumetric flow rate of dispersed and continuous phase. Finally, according to the characteristics of simple encapsulation of biological materials, we envision that the pectin hydrogels can be applied to drug delivery, food, and biocompatible materials.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.3
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• pp.159-163
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• 2007

The relationship between texture and rheological properties of mascara(oil-in-water emulsion) was analyzed in this study. The final mascara product and gelling agents(2.0 wt%) used therein, such as hydroxyethylcellulose(HC), carboxymethylcellulose(CMC), hectorite, sodium magnesium silicate (SMS), hydroxyethyl acrylate/sodium acryloyldimethyl taurate copolymer(HS), and polyacrylate 13/polyisobutene/polysorbate 20 (PPP), were measured for rheological properties. As a result, HS and PPP showed the highest adhesiveness which were related to the volumizing effect of mascara. The viscosities of HC, SMS, and HS were measured at the stress range of $1{\sim}1,000s^{-1}$. SMS, with the lowest storage modulus range of $100{\sim}1,000s^{-1}$, affected the mascara in terms of smooth texture. The results of this study suggest that the rheology of gelling agents used influences the final texture of the mascara.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.769-774
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• 1993

Defatted rice bran was microparticulated using fluidized bed opposed jet mill and air-classified at different air classifying wheel speed (ACWS) in Turboplex classifier. The median particle size and the standard deviation decreased, and concomitantly the specific surface area increased generally with increasing ACWS. The protein, fat and ash contents of the recovered rice bran increased with ACWS. The contents of minerals; magnesium, zinc, iron and manganese; increased positively with ACWS. The phytic acid content, however, was slightly higher at middle ACWS. The dietary fiber content was highest in the ACWS 15,000 rpm fraction showing 31.47%. Higher ACWS resulted in lighter colored powder. The water holding capacity (WHC) showed the maximum value at ACWS 12,000 rpm and decreased with increasing ACWS, while the oil holding capacity (OHC) increased with ACWS. The rheological property of the microparticulated rice bran/water suspension fitted to the linear model. The yield stress and viscosity of the suspension increased with ACWS. The shape of microparticulated rice bran at ACWS 21,000 rpm was spherical, and the median particle size was $3.7{\mu}m$. When cake was prepared with substitution of microparticulated rice bran at 5%, the cake height and volume increased remarkably.

• Journal of the Korean Ceramic Society
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• v.42 no.2 s.273
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• pp.132-139
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• 2005

Sintering behavior of $BaO-Nd_{2}O_3-TiO_2$ with a Pb-based glassceramics frit were investigated in order to understand an effect of glassceramics as a low temperature sintering agent on dielectric ceramics. A green sheet form was fabricated through tape casting method with the glassceramic fut added $BaO-Nd_{2}O_3-TiO_2$. The dispersion properties, rheological properties and final density of dielectric composit slurry as a function of amount and composition of organic additives was examined. The dispersants' addition was effective in controlling dispersion of the ceramics in solution. The addition of excessive dispersant showed adverse effect on dispersion. The prepared slurries, containing ceramic : powders, glass-ceramics and various kinds of organic viechles, exhibited typical shear thinning behavior. The best properties of tape casting appeared powder to solvent ratio 65 : 35 and amount of the binder 6 wt$\%$ and plasticizer 3 wt$\%$. The viscosity of the slurry was 677 cps and green/sintered density in the tape was $3.3 g/cm^3,\;5.56 g/cm^3$ respectively.

• Journal of Pharmaceutical Investigation
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• v.40 no.5
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• pp.305-311
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• 2010

The present study was aimed at preparing microemulsion-based hydrogel (MBH) for the skin delivery of itraconazole. Microemulsion prepared with Transcutol as a surfactant, benzyl alcohol as an oil and the mixture of ethanol and phasphatidyl choline (3:2) as a cosurfactant were characterized by solubility, phase diagram, particle size. MBHs were prepared using 0.7 % of xanthan gum (F1-1) or carbopol 940 (F1-2) as gelling agents and characterized by viscosity studies. The in vitro permeation data obtained by using the Franz diffusion cells and hairless mouse skin showed that the optimized microemulsion (F1) consisting of itraconazole (1% w/w), benzyl alcohol (10% w/w), Transcutol (10% w/w) and the mixture of ethanol and phospahtidylcholine (3:2) (10% w/w) and water (49% w/w) showed significant difference in the flux (${\sim}1{\mu}g/cm^2/h$) with their corresponding MBHs (0.25-0.64 ${\mu}g/cm^2/h$). However, the in vitro skin drug content showed no significant difference between F1 and F1-1, while F1-2 showed significantly low skin drug content. The effect of the amount of drug loading (0.02, 1 and 1.5% w/w) on the optimized MBH (F1-2) showed that the permeation and skin drug content increased with higher drug loading (1.5%). The in vivo study of the optimized MBH (F1-2 with1.5% w/w drug loading) showed that this formulation could be used as a potential topical formulation for itraconazole.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.639-645
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• 2016

We herein report efficient triplet-triplet annihilation upconversion (TTA-UC) achieved in various non-toxic and non-volatile vegetable oils as a UC media using platinum-octaethylporphyrin (PtOEP) and 9,10-diphenylanthracene (DPA) as a sensitizer and acceptor, respectively. Green-to-blue UC was readily achieved from PtOEP/DPA solution in vegetable oils with the quantum yield of 8% without any deoxygenation process. The UC efficiency was found to be significantly dependent on the contents of unsaturated hydrocarbon in vegetable oils and viscosity of the solution, as well. Though the Stern-volmer constant and quantum yield in vegetable oils were measured to be lower than those measured in the deaerated organic solvent, the quenching efficiency was still high enough to be 93%. In the sunflower oil, the UC threshold intensity ($I_{th}$) was approx. $100mW/cm^2$, which is far larger than the sunlight intensity, but we believe that the UC achieved in non-toxic and air-saturated media was still highly applicable to nontraditional visualization techniques such as bioimaging.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.42-48
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• 1998

Physicochemical properties of waxy maize starch and oxidized waxy maize starch with sodium hypochlorite $(0{\sim}60\;mg\;CL_2/g\;starch,40^{\circ}C,\;pH\;10,\;3.0\;hr)$ were studied. As sodium hypochlorite concentration was increased, the content of crude lipid and crude protein of the oxidized starch were decreased. And crude protein content and whiteness was considered to show negative regression. However, the crude ash content of the oxidized starch increased significantly with oxidation and bore a positive regression to the chlorine content. There was a progressive increase in the carboxyl content with increasing oxidant level. After pasting in hot water and cooling, viscosity of the oxidized starches were drastically lower than that of native starch . As carboxyl contents of the oxidized starch increased, the solubility and swelling power was increased. When waxy maize starch treated with 0, 1.5, 3.0 and 6.0% sodium hypochlorite, temperature of initial gelatinization of oxidized starch was shown to 65, 65, 60 and $50^{\circ}C$, respectively. The oxidized waxy maize starches also form clearer pastes. Water binding capacity of the oxidized starch decreased as the degree of carboxyl group substitution increased. Waxy maize starch has polygonal and some round granules which range from about 3.7 to $20\;{\mu}m$ in diameter. Surface appearance of the waxy maize starch became rough when oxidized with sodium hypochlorite. When homogenate of the oxidized waxy maize starch solution and corn germ oil was stored under room temperature for 24 hours, the emulsion stability was considered to depend on starch concentration and degree of substitution.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.369-375
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• 2004

In this study, liquid crystalline (LC) is formed using Gemini surfactant (GS) type and moisturizing effect in vivo is measured. $3.0\;wt\%$ of sodium dicocoyl ethylene diamine (PEG)-15 sulfate (SCD-PEG-15S) is used as GS and $4.0\;wt\%$ of hydrogenated dimer acid esters (HDAE) as booster. For stabilizers, $2.0\;wt\%$ of behenyl alcohol (BA) and $1.0\;wt\%$ of Iyso-lecithin (LyL) are utilized. It is stabilized in pH from 4.0 to 10.5 and the best condition is in pH 6.5. The value of viscosity is $8,000\pm500$ cP. The most excellent particles are formed within the range of 4.0 to 15.5 um. Formed LC is observed around LC particles using polarization microscope. It is also observed that lamellar gel network structure is formed around LC particles. Moisturizing effect is improved by $13.6\%$ (P<0.05) compared to control when measured 30 min later after coating samples. After 1 h, moisturizing effect is improved by 1$12.6\%$ (P<0.05) than control while showing $28.3\%$ (P<0.05) of improvement after 4 h. These results may be caused from that manufactured LC forms lamellar structure so that it has better water-holding ability and absorbance of oil increases. This formula could be utilized by delivery system (DS) on skin so that this technology can be applied for manufactuing pharmaceuticals and cosmetics.

• Korean Journal of Food Science and Technology
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• v.28 no.1
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• pp.169-178
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• 1996

Target parameters such as water solubility index (WSI), intrinsic viscosity (IV), water holding capacity (WHC), oil holding capacity (OHC), soluble dietary fiber (SDF) and microstructure were investigated on three different screw configurations during twin-screw extrusion of wheat bran. WSI of raw wheat bran (RWB) was 13.7%, while that of extrudates ranged $16.3{\sim}23.2%$ when extruded using screw configurations with 5 reverse screw elements (RSE). It was found that the moisture content of RWB greatly affected WSI of extrudates. IV of wheat bran extrudates increased from 10.6 ml/g of RWB to $37.86{\sim}44.37\;ml/g$ of extrudates extruded using 3, 4 and 5 RSE, whose trend was highly related to the moisture content of RWB and the extrusion pressure. Multiplication of IV and soluble solid (SS) content exhibited good correlation $(R^2=0.85)$ with specific mechanical energy (SME). The results suggested that SS and molecular size are an important factor governed by the SME in solubilization of wheat bran. WHC increased with increasing feed rate and moisture content, while OHC decreased. SDF increased from 2.68% of RWB to $4.32{\sim}6.48%$ of extruded wheat bran, indicating the significant breakdown of cell wall components. Microstructure of the extrudates showed the distinct patterns of degradation and solubilization of cell wall structure, depending on the moisture content of RWB.

• Resources Recycling
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• v.31 no.6
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• pp.60-65
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• 2022

This study presents the carburization process for recycling sludge, which was formed during silicon wafer machining. The sludge used in the carburization process is a mixture of silicon and silicon carbide (SiC) with iron as an impurity, which originates from the machine. Additionally, the sludge contains cutting oil, a fluid with high viscosity. Therefore, the sludge was dried before carburization to remove organic matter. The dried sludge was washed by acid cleaning to remove the iron impurity and subsequently carburized by heat treatment under vacuum to form the SiC powder. The ratio of silicon to SiC in the sludge was varied depending on the sources and thus carbon content was adjusted by the ratio. With increasing SiC content, the carbon content required for SiC formation increased. It was demonstrated that substoichiometric SiC_x (x<1) was easily formed when the carbon content was insufficient. Therefore, excess carbon is required to obtain a pure SiC phase. Moreover, size reduction by high-energy milling had a beneficial effect on the suppression of SiC_x, forming the pure SiC phase.