• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.151-161
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• 2017

A TSL (Thin Spray-on Liner) has a higher initial strength and faster construction time than conventional cementitious shotcrete. Because of its high adhesion and tensile strength, the TSL reinforced concrete show a characteristic like composite materials. In this study, to consider an application to the conventional design method, ASD (allowable stress design), numerical study was used. In the numerical analysis, material and contact properties were adopt from previous studies. Then a thickness of concrete in the tunnel was evaluated with the TSL reinforced case by the ASD concept. In other words, bending compressive stress, bending tensile stress and shearing force of the concrete were considered to determine a thickness of concrete lining by the given boundary conditions. From the numerical analysis, there was no tendency to show by the ASD because the ASD is based on the elastic theory while the TSL typically contributes to reinforcement after yielding.

• Clinical and Experimental Reproductive Medicine
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• v.25 no.2
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• pp.207-216
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• 1998

Certain types of somatic cells, as well as follicular cumulus cells associating with mammalian oocytes, are known to produce beneficial effects on in vitro fertilization and pre implantation development of mammalian eggs when they are present in oocyte culture medium. To investigate the nature of the effects of somatic cells, the resistance of mouse oocytes against chymotrypsin treatment was examined after culture within various cell conditioned media. When mouse oocytes matured for 17-18 hr in the presence of cumulus cells were treated with 1 % chymotrypsin, half of them remained still alive even after 240 min $(t_{50}>240.0)$. In contrast half of mouse oocytes cultured without cumulus cells underwent degeneration within 65.0 min $(t_{50}=65.0{\pm}13.2min)$ of the same treatment. To see if the effects were duc to the secretory products of cumulus cells, mouse cumulus cells were cultured for 20 hr in medium containing 0.4% BSA and the supernatant of culture medium (conditioned medium) was taken. After maturation in the cumulus cell conditioned medium, mouse oocytes exhibited $t_{50}=190.0{\pm}10.8$ min upon chymotrypsin treatment whereas half of oocytes cultured without conditioned medium degenerated within 25.5 min. Human granulosa cell conditioned medium gave similar effects such that oocytes matured in conditioned medium exhibited $t_{50}=183.3{\pm}19.1$ min while $t_50$ of control group oocytes was $60.0{\pm}6.8$ min, Oocytes matured in vero cell conditioned medium exhibited $t_{50}=196.7{\pm}8.8$ min. On the other hand, amniotic cell conditioned medium resulted in the chymotrypsin resistance of $t_{50}=80.0{\pm}8.4$ min which was not statistically different from the control value of $t_{50}=48.0{\pm}13.2$ min. Based upon these results, it is suggested that certain somatic cell types including cumulus cells might change the biochemical properties of mouse oocyte membrane during meiotic maturation as revealed by the enhanced resistance against chymotrypsin treatment. Such effects of somatic cells appear to be mediated via the secretory products rather than direct communication between somatic cells and oocytes.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.32 no.4 s.59
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• pp.209-217
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• 2006

Emulsion is a dispersion system among liquids which are not miscible together. There are numerous cosmetic raw materials which have different physicochemical properties. Therefore, emulsion technology is very useful in cosmetics. With the development of emulsifier, several emulsification technologies have been developed. Since HLB method by Griffin in 1950's, PIT method, gel method, and D-phase methods, etc, have been developed. Recently, the application of natural emulsifier and polymeric emulsifier increases in cosmetics in order to achieve enhanced safety and biocompatibility. Besides nano-emulsion, multiple-emulsion, liquid crystal emulsion, and Pickering emulsion have been developed and applied as means of differentiating appearance and texture of products and achieving enhanced delivery of active ingredients. Meanwhile, the application studies of nano-dispersed structural system such as liposome or cubosome are on progress. Liposome is a bi- or multi-lamella layer dispersion system composed of amhiphilic molecules - phospholipids which are main components of plasma membrane. Cubosome also is a nano-sized dispersion system composed of a specific molecule like glyceryl monoloeate derived from natural products. And it has a cubic bicontinuous structure in water due to its unique molecular structure. Incorporating compounds (active materials) into such nano-particles can increase biocompatibility and delivery efficiency of target compounds. Manufacturing process and application of cosmetic emulsions and nano-particles are briefly introduced in this paper.

• 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 Microbiology
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• v.46 no.3
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• pp.270-277
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• 2010

In order to manufacture Bacillus cereus-free fermented soybean products, an antimicrobial agentproducing isolate against B. cereus was obtained from 150 traditionally fermented soybean products. The morphological and biochemical tests and the phylogenetic relationship among 16S rRNA gene sequences indicated that the isolate named as the strain SCK 121057 was most closely related to Bacillus licheniformis. The B. licheniformis isolate began to produce the antimicrobial agent after 48 h of incubation. The agent was nonproteinaceous and insensitive to heat, long term storage and protease K. Electron microscopic observation indicated that the agent attacked the membrane of B. cereus, leaving the ghost cell. The isolate inhibited growth of B. subtilis, Lactobacillus brevis and various types of pathogenic strains including Escherichia coli, E. faecalis, Micrococcus luteus, Staphylococcus aureus, Aspergillus flavus, A. ochraceus, and A. parasiticus as well as B. cereus. After coinoculation of B. licheniformis SCK 121057 and B. cereus in the ratio (as the basis of CFU/g sample) of 10 to 1 on the surface of cooked soybeans, cell numbers of B. cereus had been dramatically reduced after 31 days of incubation compared to those of single inoculation of B. cereus.

• Applied Biological Chemistry
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• v.42 no.1
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• pp.12-19
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• 1999

To improve biopolymer productivity and properties of Bacillus strains, protoplast fusion was performed between biopolymer producing Bacillus subtilis K-1 and lactose utilizing Bacillus coagulans. The results were as follows; Protoplasts mixed in fusion fluid containing 33% PEG 6000, 1% PVP and 10 mM $CaCl_2$ were reacted for 5 min at $37^{\circ}C$ and then centrifused protoplasts were directly overlaid on the selective media containing $100\;{\mu}g/ml$ antibiotics and incubated for 3 days. At this conditions, the frequency of protoplast fusion was generally in the range of $4.6{\times}10^{-5}\;to\;1.8{\times}10^{-7}$ in ratio. Segregation ratio was observed between 1 to 6% indicating genetic stability of all the fusants. Fusants growth were also observed on the media contained amino acid and antibiotics as required marked materials. DNA contents of the selected fusants were 1.6 to 2.7 times more than that of parent strains. With observation by TEM microscopy, spherical protoplasts were first released from the swollen parental cells and then contracted to fuse in the process of fusion. And fused cells were observed representative vesicle. Originally, the parental cells were observed as in the morphology of thick-walled and double membrane-surrounded rod shape with TEM microscopy.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.417-426
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• 1997

Rice bran protein hydrolysates were prepared and some of their physicochemical properties were investigated to utilize rice bran as starting material for functional food ingredient. Rice bran proteins (RBP) were prepared from defatted rice bran by alkaline extraction and isoelectric precipitation. The enzyme for hydrolysis of RBP was selected through measuring relative activity by pH-drop method and comparing the degree of hydrolysis (DH) of hydrolysates. The enzymatic hydrolysates prepared by $Esperase^{\circledR}$ treatment were partitioned into two fractions by ultrafiltration(UF) with a 10 kDa molecular weight cut-off membrane. Each fraction was applied to a cholic acid-conjugated ${\omega}-aminohexyl$ Sepharose 4B column and the bile acid-binding components were obtained by eluting with deoxycholate. Gel permeation chromatography on a Sephadex G-50 column revealed that molecular weight of the bile acid-binding fraction of UF permeate was distributed in ranges of $2\;kDa{\sim}10\;kDa$ and $0.2\;kDa{\sim}0.6\;kDa$. Three peaks (R-1, R-2 and R-3) were obtained by prep-HPLC of bile acid-binding fraction of UF retentate and analyzed for total and free amino acid composition. The results showed that proline content of the bile-acid binding polypeptides and peptides was four times as much as that of rice bran protein and that the peak corresponding to higher average hydrophobicity had a higher free amino acid content. Average hydrophobicity slightly increased with enzymatic hydrolysis.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.39-39
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• 2003

In our previous study, WEHI-231, an immature B cell line, showed intractable increase in [C $a^{2+}$]$_{c}$ after the B-cell receptor (BCR) ligation and treatment with 2-aminoethoxydiphenylborate (2-APB), which was never observed in Bal-17, a mature B cell line (Nam et al., 2003, FEBS Lett). In this study, a whole cell voltage clamp study revealed a specific expression of a novel type of $K^{+}$ current, namely voltage-independent background-type $K^{+}$ channels (IK-bg), in WEHI-231 cells. IK-bg was dramatically increase by the application of 2-APB (50 $\square$M), which induced severe hyperpolarization of WEHI-231 from -45 ㎷ to -90 ㎷, When dialyzed with $Mg^{2+}$ and ATP-free pipette solution, a spontaneous development of IK-bg and membrane hyperpolarization were observed. IK-bg was insensitive to classical $K^{+}$ channel blockers (TEA, glibenclamide, $Ba^{2+}$(1 mM)), whereas blocked by quinine and quinidine in a voltage-dependent manner ($IC_{50}$/=6~9 $\square$M at +60㎷). Phorbol myrstate, a PKC activator, decreased the amplitude of IK-bg. Extracellular acidification (pH 6.5) slightly inhibited IK-bg. Arachidonic acid, riluzole, or hyposmotic stress could not affect the IK-bg after the full development by the intracellular dialysis with Mg-ATP-free solution. In a cell-attached mode of single channel recording from WEHI231, we found two types of voltage-independent $K^{+}$ channels with unitary conductance of 300 pS and 120 pS, respectively. Both channels showed very short mean open times and their open probabilities were increase by the application of 2-APB. In Bal-17 cells, no such $K^{+}$ current was observed in 50 cells tested. In summary, WEHI-231 immature B cells express background $K^{+}$ channels. The pharmacological properties and the large unitary conductance suggest that novel types of two-pore domain $K^{+}$ channels (2-P-K channels) might be expressed in WEHI-231, which may provide an intriguing targets of signal transduction in the immature B lymphocytes.e B lymphocytes.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.476-481
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• 2013

Ethylbenzene (EB) which has a similar physical properties with p-xylene (pX) was separated from EB/pX mixture by using MFI-type zeolite (TS-1, ZSM-5, and Silicalite-1) coated membranes. The zeolites were synthesized by microwave method to reduce the synthesis time and uniformly formed zeolite particles were coated on the ${\alpha}$-almina tubular support with a thickness of $3-4{\mu}m$. Separation factor and permeation flux of the synthesized zeolite coated membranes were measured to survey the best performance of ethylbenzene separation from different composition of EB/pX mixtures. When the EB/pX mixture of 5:5 molar ratio applied for the separation experiment, it represented the highest separation factor. We also have studied about the effect of the atomic composition of zeolites on the separation performance within the temperature range from 160 to $220^{\circ}C$. TS-1 showed the highest permeation flux of $1,666mol/m^{2*}s^*Pa$ and Silicate-1 showed the highest separation factor of 1.73 at $200^{\circ}C$ respectively.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.641-646
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• 2018

Sodium borohydride, $NaBH_4$, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFCs). Properties of $NaBH_4$ hydrolysis reaction using activated carbon supported Co-B/C, Co-P-B/C catalyst were studied. BET surface area of catalyst, yield of hydrogen, effect of $NaBH_4$ concentration and durability of catalyst were measured. The BET surface area of carbon supported catalyst was over $500m^2/g$ and this value was 2~3 times higher than that of unsupported catalyst. Hydrogen generation of activated carbon supported catalyst was more stable than that of unsupported catalyst. The activation energy of Co-P-B/C catalyst was 59.4 kJ/mol in 20 wt% $NaBH_4$ and 14% lower than that of Co-P-B/FeCrAlloy catalyst. Catalyst loss on activated carbon supported catalyst was reduced to about 1/3~1/2 compared with unsupported catalyst, therefore durability was improved by supporting catalyst on activated carbon.