• Food Science and Preservation
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• v.16 no.2
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• pp.266-275
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• 2009

To develop new high-quality Yakchobugak, features of Lactococcus lactis-fermented waxy rice paste after addition of some colored powdered agro-food products were investigated. Total and reducing sugars of waxy rice paste fermented by lactic acid bacteria were higher than those of control raw waxy rice paste. Total acidity gradually increased as powder concentration rose, being 1.02-1.56% and 0.96-1.87% in samples fermented with Cucurbita maxima and Capsicum annuum powders, respectively; these values were 3-4 times those in rice fermented with other powders. Fermented waxy rice paste viscosities were lower than those of non-fermented samples. The viscosities of samples fermented with Curcuma longa and Opuntia ficus powders were in the range $100-160{\times}10^4$ centipoise($mPa{\cdot}s$), and those of pastes fermented with Robus coreanus and Camellia sinensis extracts were under $40{\times}10^4mPa{\cdot}s$. Hunter color lightness(L) values decreased and yellowness(b) values rose after fermentation. Waxy rice paste fermented with Robus coreanus showed uniform particle size distribution, and many pores, by scanning electron micrography.

• Food Science and Preservation
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• v.21 no.3
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• pp.381-387
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• 2014

Food irradiation is one of the successful modern techniques used to preserve food. However, it needs very careful control. Detection of irradiated food is of prime importance to facilitate global trade and consumer assurance, choice, and protection. This study was performed to evaluate the radiation-induced hydrocarbon content of dried squid and octopus by e-beam irradiation. The samples were collected from supermarkets all over South Korea and irradiated with an e-beam at 0, 1, 3, 5, 7, and 10 kGy doses. Lipids were extracted with soxhelt, and the hydrocarbons induced with irradiation were separated via solid phase extraction (SPE) and identified via gas chromatography mass spectrometry (GC/MS). The major induced hydrocarbons in the irradiated dried squid and octopus were 1-tetradecene and pentadecane derived from palmitic acid and 1-hexadecene and heptadecane from stearic acid. The concentration of hydrocarbons differed from the composition of the fatty acid at the same radiation and increased according to the level of the radiation dose. The hydrocarbons induced by e-beam irradiation, including 1-tetradecene, 1-hexadecene, and heptadecane, were confirmed to have been the irradiation marker compounds. Therefore, they can be used to distinguish the e-beam-irradiated dried squid and octopus from the non-irradiated ones.

• Membrane Journal
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• v.15 no.2
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• pp.147-156
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• 2005

It is well-known that polyethersulfone (PES) has high $CO_2$ selectivity over $N_2\;(or\;CH_4)$ and excellent pressure resistance of $CO_2$ plasticization among muy commercialized engineering plastics[1-4]. Asymmetric PES hollow fiber membranes for flue gas separation were developed by dry-wet spinning technique. The dope solution consists of PES, NMP and acetone. Water and water/NMP mixtures are used in outer and inner coagulants, respectively. Gas permeation rate (i.e., permeance) and $CO_2/N_2$ selectivity were measured with pure gas, respectively and the micro-structure of hollow fiber membranes was characterized by scanning electron microscopy. The effects of polymer concentration, ratio of NMP to acetone, length of air gap, evaporation condition and silicone coating were investigated on the $CO_2/N_2$ separation properties of the hollow fibers. Optimized PES hollow fiber membranes exhibited high permeance of $25\~50$ GPU and $CO_2/N_2$ selectivity of $30\~40$ at room temperature and have the apparent skin layer thickness of about $0.1\;{\mu}m$. The developed PES hollow fiber membranes, would be a good candidate suitable for the flue gas separation process.

• Korean Journal of Medicinal Crop Science
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• v.16 no.5
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• pp.320-325
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• 2008

Machilus thunbergii has been showed relation to antimicrobial activity on minimal inhibitoty concentration (MIC) and colony forming inhibitory activity (CFIA) test, so that can be used to food preservatives for green vegetable. Nanoparticles has been made of edible materials. 80% of the nanoparticles has been characterized by image analyser and electron microscopy, showing in the range under 300 nm diameter. The sprayed nanoparticles remained on the surface of chicon even after washing by dilution water, then activate biological activities for storage of chicon with storing and releasement system of extracts. Chicon treated nanoparticle has been kept fresh condition about 2 months longer than 3 weeks of the non-treated control. It can be tell that treatment with nanoparticle of M. thunbergii extracts extends storage time of chicon possibly by inhibition of ethylene production through efficiency control on cell breathing.

• Membrane Journal
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• v.26 no.4
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• pp.318-327
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• 2016

In this study, alginate/poly(ethylene oxide) (PEO), and chitosan/PEO solution are prepared by dissolving alginate and chitosan into specific solvent for electrospinning. Solutions are poured into 10 mL plastic syringes with a metal nozzle supplied a high voltage power. The solution of alginate and chitosan is controlled by polymer concentration, temperature, relative humidity, applied voltage, distance from nozzle and flow rate of solution. Morphologies of fabricated nanofiber are observed by scanning electron microscopy (SEM). Optimal conditions for electrospinning of alginate nanofiber membrane are 2 wt% of alginate, 2 wt% of PEO at $60^{\circ}C$, 15 cm from the nozzle, $8{\mu}m/min$ flow rate and 20~24 kV. The conditions for elctrospinning of chitosan nanofiber membrane are 2 wt% of chitosan, 2 wt% PEO at $25^{\circ}C$, 15 cm from the nozzle, $8{\mu}m/min$ flow rate and 24 kV. The fabrication conditions of complex nanofiber prepared with chitosan and alginate are 20 cm from the nozzle, $8{\mu}m/min$ flow rate and 26 kV.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.427-434
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• 2015

Most of halophilic archaea are found in the various hypersaline environments including solar saltern, salt lake with very high salt concentration. The present study is about isolation and characterization of halphilic archaea from Gomso solar saltern known as a representative high salt environment in Korea. In order to isolate the halophilic archaea, we prepared and used high salt medium. Finally, total 7 strains obtained were tentatively identified based on comparative similarity analysis for 16S rRNA gene sequence and physiological traits. All halophilic archaea belonged to Haloruburm, Halogeometriucm, Halobacterium, and Haloarcula genera. These isolates were all Gram-staining negative, and growth was not observed using nitrate as an alternative electron acceptor under anaerobic conditions. In addition, all isolates required about 12-30% (w/v, NaCl) salt. This case study might provide basic information on microbial isolation technologies and related research in halophilic microorganisms from domestic halophilic environments, and contribute to obtaining useful indigenous halophilic archaea in a variety of extreme environmental conditions.

• Korean Journal of Materials Research
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• v.9 no.4
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• pp.349-354
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• 1999

The temperature dependences of the Hall coefficient, carrier mobility, electrical resistivity, Seebeck coefficient, thermal conductivity, and figure-of-merit of the undoped and $CdI_2$-doped 90% $Bi_2Te_3-10% Bi_2Se_3$, single crystals, grown by the Bridgman method, have been characterized at temperatures ranging from 77K to 600K. The saturated carrier concentration and degenerate temperature of the undoped 90% $Bi_2Te_3-10% Bi_2Se_3$ single crystal are $5.85\times10_{18}cm^{-3}$ and 127K, respectively. The scattering parameter of the 90% $Bi_2Te_3-10% Bi_2Se_3$ single crystal is determined to b -0.23, and the electron mobility to hole mobility ratio ($\mu_e/\mu_h)$ is 1.45. The bandgap energy at 0K of the 90% <$Bi_2Te_3-10% Bi_2Se_3$ single crystal is 0.200 eV. Adding $CdI_2$as a donor dopant, a maximum figure-of-merit of $3.2\times10^{-3}/K$$CdI_2$-doped specimen.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.1
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• pp.20-26
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• 2001

Titanium boride ($\textrn{TiB}_{x}$) films were deposited on (100) silicon substrates at the substrate temperature of $500^{\circ}C$ by means of the co-evaporation of titanium and boron evaporants during deposition. The co-evaporation method makes it possible to deposit the non-stoichiometric films with different boron-to-titanium ratio($0{\le}B/Ti \le 2.5$). The resistivity increases linearly as the boron-to-titanium ratio in the as-deposited films is increased. The surface roughness of $\textrn{TiB}_{x}$ films is changed as a function of the boron-to-titanium ratio. The XRD spectrum for pure titanium film shows a highly (002) preferred orientation. For B/Ti=0.59 ratio only a single TiB phase that shows a (111) preferred orientation is observed. However, the $\textrn{TiB}_{x}$ phase with the hexagonal structure of the $AlB_2$(C32) type appears as the boron concentration increase, and only a single $\textrn{TiB}_{x}$ phase is observed for $B/Ti \ge 2.0$ ratio. The $\textrn{TiB}_{x}$/Si samples reveal a tensile stress (3~$20{\times}^9$dyn/$\textrm{cm}^2$) in the overall composition of the films, although the magnitude of the residual stresses is depended on the nominal B/Ti ratio.

• Clean Technology
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• v.26 no.1
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• pp.1-6
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• 2020

Rapid expansion of supercritical solution (RESS) process was used to make molsidomine (MOL) loaded peracetyl-β-cyclodextrin (PAc-β-CD) nanoparticles, which were collected into the air. The effect of the concentration of the drug PAc-β-CD (0.5 and 1 wt%), extraction temperature (45 ~ 60 ℃), nozzle length (5 ~ 20 mm) and internal diameter (ID) (50 ~ 150 μm) of a capillary, and spray distance on the particle size and morphology of the resulting particles were investigated. The interaction of a drug and PAc-β-CD was confirmed by ¹H-NMR spectroscopy while the particle size was measured by means of a scanning electron microscope. It was found that increasing the temperature from 45 ℃ to 60 ℃ and decreasing the nozzle diameter from 150 μm to 50 μm had an increasing effect on the average particle size, while increasing the spray distance led to a decrease in the average particle size at a constant pressure of 34.5 MPa and temperature of 45 ℃. With 0.5 wt% of PAc-β-CD, the capillary nozzle of short length (5 mm) and small ID (50 μm) gave the smallest size (165 nm). The obtained nanoparticles showed increased dispersity and solubility in oil. The oil suspension of the inclusion complex showed increased sustainability, which can increase the in-vitro controlled release time of the drug.

• Journal of Environmental Health Sciences
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• v.43 no.3
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• pp.194-201
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• 2017

Objectives: Zinc oxide nanoparticles (ZnO NPs) are widely used in various commercial products, but they are exposed to the environment and can induce toxicity. In this study, we investigated the environmental fate and bioaccumulation of ZnO NPs in a microcosm. Methods: The microcosm was composed of water, soil (Lufa Soil 2.2) and organisms (Oryzias latipes, Neocaridina denticulata, Semisulcospira libertina). Point five and 5 mg/L of ZnO NPs were exposed in the microcosm for 14 days. Total Zn concentrations were measured using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and intracellular NPs were observed using Transmission Electron Microscopy (TEM). Results: In the initial stages of exposure, the Zn concentrations in water increased in all exposure groups and then decreased, while the Zn concentration in soil increased after three hours for the 5 mg/L solution. Zn concentrations also showed increasing trends in N. denticulata and S. libertina at 0.5 and 5 mg/L, and in O. latipes at 5 mg/L. Accumulation of NPs was found in the livers of O. latipes and hepatopancreas of N. denticulata and S. libertina. Conclusions: In the early stages of exposure, ZnO NPs remained in the water, and then were transported to the soil and test species. Unlike other species, total Zn concentrations in N. denticulata and S. libertina increased for both 0.5 mg/L and 5 mg/L. Therefore, ZnO NPs were more easily accumulated in zoobenthos than in fish.