• Journal of Pharmaceutical Investigation
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• v.30 no.3
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• pp.167-172
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• 2000

The purpose of this study is to develop a transurethral liquid suppository containing prostaglandin $E_1\;(PGE_1)-loaded$ microemulsion, which undergoes a phase transition to gels at body temperature. The effects of oils, ethanol as solvent and HCl as pH-controlling agent on the physicochemical properties of liquid suppositories composed of poloxamer P 407, P 188 and carbopol was investigated. The stability of $PGE_1$ and release of $PGE_1$ from liquid suppository were evaluated. Oils such as Neobee and soybean oil significantly decreased the gelation temperature but increased the gel strength of liquid suppository due to their strongly binding with the components of liquid suppository base. However, ethanol slightly did the opposite. The pH of liquid suppositories hardly affected the gelation temperature and gel strength due to addition of very small HCl (0.005-0.01%). A liquid suppository [$PGE_1/P$ 407/P 188/carbopol/Neobee/ethanol/HCl (0.2/14/14/0.4/7/2/0.005%)], which had the gelation temperature $(34.2{\pm}0.6^{\circ}C)$ and gel strength $(31.35{\pm}4.37\;sec)$ suitable for liquid suppository system, was easily administered and not leak out from the body. About 60% of $PGE_1$ was released out within 2 h from this formulation. It was shown that the release of $PGE_1$ was proportional to the square root of time, indicating that $PGE_1$ might be released from the suppository by Fickian diffusion. It was stable at $4^{\circ}C$ for at least 2 months. The results suggest that transurethral liquid suppository containing prostaglandin $E_1-loaded$ microemulsion is thought to be a convenient, safe and effective dosage form for $PGE_1$. However, it should be further developed as a more convenient and stable dosage form for $PGE_1$.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.233-242
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• 1988

The uranium(VI) complexes with new unsaturated macrocyclic ligands of cryptand types and the neodymium(III) complexes with cryptand 222 and DBC ligands have been investigated polarographically in dimethylsulfoxide solvent. The reduction states, electron numbers involved in the reduction process, effects of the added acid on the polarograms of complexes, and the mechanisms of the reduction electrode reactions have been examined. The stability constants and mole-ratio of new complexes were also obtained by polarographic method. The reaction of ligands was controlled by the diffusion in the reduction with four electrons at a step, whereas the redox reaction with six electrons at three steps in $UO_2\;^{2+}$ complexes with macrocyclic ligands and the redox reaction with one electron at a step in $Nd^{3+}$ complexes with cryptand 222 and DBC have been observed. The imine ligands formed stable complexes with uranium(VI) above pH 7.0, and the neodymium(III) complexes with cryptand 222 and DBC ligands were stable above pH 4.0.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.2
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• pp.91-101
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• 2009

in the cosmetics and medical supply field as a antioxidant material. The stable nano particle emulsion of skin toner type containing VEA was prepared. To evaluate the skin permeation, experiments on VEA permeation to the skin of the ICR outbred albino mice (12 weeks, about 50 g, female) and on differences of solubility as a function of receptor formulations was performed. The analysis of nano-emulsions containing VEA 0.07 % showed that the higher ethanol contents the larger emulsions were formed, while the higher surfactant contents the size became smaller.In this study, vitamin E acetate (VEA, tocopheryl acetate), a lipid-soluble vitamin which is widely used A certain contents of ethanol in receptor phase increased VEA solubility on the nano-emulsion. When the ethanol contents were 10.0 % and 20.0 %, the VEA solubility was higher than 5.0 % and 40.0 %, respectively. The type of surfactant in receptor solution influenced to VEA solubility. The comparison between three kind surfactants whose chemical structures and HLB values are different, showed that solubility of VEA was increased as order of sorbitan sesquioleate (Arlacel 83; HLB 3.7) > POE (10) hydrogenated castor oil (HCO-10; HLB 6.5) > sorbitan monostearate (Arlacel 60; HLB 4.7). VEA solubility was also shown to be different according to the type of antioxidant. In early time, the solubility of the sample including ascorbic acid was similar to those of other samples including other types of antioxidants. However, the solubility of the sample including ascorbic acid was 2 times higher than others after 24 h. Franz diffusion cell experiment using mouse skin was performed with four nano-emulsion samples which have different VEA contents. The emulsion of 10 wt% ethanol was shown to be the most permeable at the amount of 128.8 ${\mu}g/cm^2$. When the result of 10 % ethanol content was compared with initial input of 220.057 ${\mu}g/cm^2$, the permeated amount was 58.53 % and the permeated amount at 10 % ethanol was higher 45.0 % and 15.0 % than the other results which ethanol contents were 1.0 and 20.0 wt%, respectively. Emulsion particle size used 0.5 % surfactant (HCO-60) was 26.0 nm that is one twentieth time smaller than the size of 0.007 % surfactant (HCO-60) at the same ethanol content. Transepidermal permeation of VEA was 54.848 ${\mu}g/cm^2$ which is smaller than that of particlesize 590.7 nm. Skin permeation of nano-emulsion containing VEA and difference of VEA solubility as a function of receptor phase formulation were determined from the results. Using these results, optimal conditions of transepidermal permeation with VEA were considered to be set up.

• Microbiology and Biotechnology Letters
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• v.43 no.3
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• pp.187-194
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• 2015

In this study, L. plantarum, when reacting with the culture media of potential pathogenic bacteria, exhibited an increase in growth rate and antimicrobial activity. In order to examine the characteristics and the nature of the reaction with the bacteria, this study carried out experiments involving culturing the test bacteria in M9 minimal media. Subsequently, the supernatant was incrassated by the decompression-drying method. Through colony forming unit assay, it was confirmed that L. plantarum had the function of growth inhibition to various bacteria. After culturing L. plantarum with bacterial media, the growth rate of L. plantarum was measured by absorbance (OD₆₀₀), the results showed that the growth rate (E. coli treatment group: OD₆₀₀ = 0.848, S. typhimurium treatment group: OD₆₀₀ = 0.848) increased, as compared with the non-treated control group (OD₆₀₀ = 0.48). In contrast, the concentrate itself did not induce the growth of L. plantarum. These results were observed as a universal phenomenon of the Lactobacillus species. Moreover, the increase in antimicrobial activity was observed in L. plantarum, which reacted with the culture media of E. coli and S. typhimurium, through a disc diffusion assay, and the result of growth inhibition against various bacteria was induced. Finally, based on the analysis results of the characteristics of bacteria culture media, which increased the growth rate of L. plantarum and antibacterial activity, the bacterial media had a tolerance for catabolic enzymes, pH 2−8 and heat. Therefore, this substance can be said to be a small molecule which is highly stable under various conditions.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.2
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• pp.34-41
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• 2011

Wrought nickel-base superalloys are being considered as the structural materials in very-high temperature gas-cooled reactors. To understand the effects of impurities, especially oxygen, in helium coolant on the mechanical properties of Alloy 617, creep tests were performed in high temperature flowing He environments with varying $O_2$ contents at 800, 900, and $1000^{\circ}C$. Also, creep life in static He was measured to simulate the pseudo-inert environment. Creep life was the longest in static He, while the shortest in flowing helium. In static He, impurities like $O_2$ and moisture were quickly consumed by oxidation in the early stage of creep test, which prevented further oxidation during creep test. Without oxidation, microstructural change detrimental to creep such as decarburization and internal oxidation were prevented, which resulted in longer creep life. On the other hand, in flowing He environment, surface oxides were not stable enough to act as diffusion barriers for oxidation. Therefore, extensive decarburization and internal oxidation under tensile load contributed to premature failure resulting in short creep life. Limited test in flowing He+200ppm $O_2$ resulted in even shorter creep life. The oxidation samples showed extensive spallation which resulted in severe decarburization and internal oxidation in those environments. Further test and analysis are underway to clarify the relationship between oxidation and creep resistance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.605-610
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• 2006

We have investigated $Al_{0.25}Ga_{0.75}As/In_{0.2}Ga_{0.8}As$ structures for pseudomorphic high electron mobility transistor(pHEMT), which were grown by molecular beam epitaxy(MBE) and consequently annealed by rapid thermal anneal(RTA), using Hall measurement, photoluminescence, and transmission electron microscopy (TEM). According to intensity and full-width at half maximum maintained stable at the same energy level, the quantized energy level in $Al_{0.25}Ga_{0.75}As/In_{0.2}Ga_{0.8}As$ quantum wells was independent of the RTA conditions. However, the Hall mobility was decreased from $6,326cm^2/V.s\;to\;2,790cm^2/V.s\;and\;2,078cm^2/V.s$ after heat treatment respectively at $500^{\circ}C\;and\;600^{\circ}C$. The heat treatment which is indispensable during the fabrication procedure would cause catastrophic degradation in electrical transport properties. TEM observation revealed atomically non-uniform interfaces, but no dislocations were generated or propagated. From theoretical consideration about the mobility changes owing to inter-diffusion, the degraded mobility could be directly correlated to the interface scattering as long as samples were annealed below $600^{\circ}C$ lot 1 min.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.4
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• pp.549-554
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• 2013

With the synthesis of graphene on Cu using CVD, it was tried to show the behavior of graphene growth depending on the size and orientation of Cu grain. It was found out that even under the same temperature and pressure the use of different gases influences on the diffusion rate of Cu. As compared to Ar gas, Cu grain growing bigger under $H_2$ and $CH_4$ was resulted in bigger graphene grain. Corrosion resistance was evaluated by potentiodynamic polarization test in room temperature and found out that the graphene on Cu was more stable in order of 10 than pure Cu due to the chemical stability of graphene. The future work of this research will focus on the synthesis of graphene having no defects including grain boundaries, and its engineering use.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.4
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• pp.296-303
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• 2005

A strain named as HJ35 was isolated from the skin of sixty-five men and fourteen women for acne therapy, in order to find an effective antimicrobial agent against Propionibacterium acnes. Isolate HJ35 was identified as Enterococcus faecium based on 16 rDNA sequence and produced enterocin HJ35 having antimicrobial activities against most lactic acid bacteria, En­terococcus spp., Staphylococcus aureus, S. epidermidis, Clostridium perfringens, some bacilli, Mi­crococcus flavus, Listeria monocytogenes, L. ivanovii, Escherichia coli, Pseudomonas fluorescens and Propionibacterium acnes, in the modified well diffusion method. Especially, enterocin HJ35 showed a bactericidal activity against Propionibacterium acnes P1. The antimicrobial activity of enterocin HJ35 was disappeared completely with the use of protease XIV. But enterocin HJ35 activity is very stable at high temperature (up to $100^{\circ}C$ for 30 min), in wide range of pH (3.0${\~}$9.0), and by treatment with organic solvents. The apparent molecular mass of enterocin HJ35 was estimated to be approximately 4${\~}$4.5 kDa on detection of its bactericidal activity after SDS-PAGE. In batch fermentation of E. faecium HJ35, enterocin HJ35 was produced at the mid­log growth phase, and its maximum production was obtained up to 2,300 AU/mL at the late stationary phase. By employing fed-batch fermentation, the enhanced production of enterocin HJ35 was achieved up to 12,800 AU/mL by feeding with 10 g/L glucose or 6 g/L lactate.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.1
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• pp.40-50
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• 1994

For an accurate prediction of the temperature field induced by heated water discharged into a shallow crossflow, a two-dimensional near-field numerical model is developed. It is based on a 4-equation turbulence model in which the transport equations for mean of the temperature fluctuation squared and its dissipation rate are added to those of a 2-equation turbulence model which cannot give the information of the thermal time scale ratio. Vertical diffusion is also considered by including buoyancy production and turbulence heat flux terms. The developed model is applied to a steady flow in an open channel with simple geometry and the results are compared with existing experimental data and those of the already established 2-equation turbulence model. Numerical results of the model agree with the experimental data better than those of the 2-equation model. The present model also simulates quite adequately the physical characteristics of thermal discharge in the jet entrainment and stable regions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.2
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• pp.213-223
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• 1997

Premixed flame is better than diffusion flame to accomplish a high loading combustion. Since the turbulent characteristics of unburned mixture has a great influence on the flame structure, it is general that many researchers realize a high loading combustion with strengthening turbulent intensity of unburned mixture. Because turbulent premixed flame reacts efficiently on the condition of distributed reaction region, we made high turbulent premixed flame in the doubled impingement field. We investigated turbulent characteristics of unburned mixture with increasing shear force and visualized flames with direct and Schlieren photographs. And the combustion characteristics of flame was elucidated by instantaneous temperature measurement with a thermocouple, by ion currents with a micro electrostatic probe, by radical luminescence intensity and local equivalence ratio. Extremely strong turbulent of small scale is generated by impingement of mixture, and turbulent intensity of unburned mixture increased with the mean velocity. As a result of direct photographs, visible region of flame became longer due to increasing central direction flux. But as strengthed turbulent intensity, visible region of flame turned to shorter and reaction occurred efficiently. As strengthened turbulent intensity of mixture with increasing flux of central direction, maximum fluctuating temperature region moved to radial direction and fluctuation of temperature became lower. The reason is influx of central direction which caused flame zone to move toward radial direction, to maintain flame zone stable and to make flame scale smaller.