• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.332-336
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• 1998

The effect of ripening temperature, pH and salinity on the formation of Nnitrosamine (NA) during Kimchi fermentation and in vitro was studied, respectively. During Kimchi fermentation for six weeks at cold storage temperature ($4^{\circ}C$) and room temperature ($16{\pm}2^{\circ}C$), the contents of nitrite and dimethylamine (DMA) showed variation at room temperature but no variation at cold storage temperature. The maximum generation of nitrosodimethylamine (NDMA) resulted low content ($2.69\;\mu\textrm{g}/kg$) at cold storage temperature but started to increase after one week fermentation and reached to the 18-fold higher generation ($49.6\;\mu\textrm{g}/kg$) at room temperature. During Kimchi fermentation, no correlation was observed between the variation of nitrite and DMA content and the generation of NDMA. However, pH showed effective relation to NDMA generation such as the highest NDMA generation was obtained at lowest pH 4. During in vitro test, higher temperature and lower pH resulted more NDMA generation and generation amount was affected more by pH. Also, the salinity of Kimchi provided inhibitory effects on the formation of NDMA. NDMA was produced $5.86\;\mu\textrm{g}/kg$ at normal salinity (2.5%) but $90.9\;\mu\textrm{g}/kg$ at lower salinity (15%) after three week. The higher salinity showed lower formation of NDMA in vitro test, too.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.673-681
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• 1995

Surface morphology and preferred orientation of 20${\mu}{\textrm}{m}$ gold electrodeposit formed from aqueous solution of the sodium gold sulfite were studied in terms of current density, plating temperature and Au concentration. As the current density changed from 13.0mA/$\textrm{cm}^2$ to 4.6mA/$\textrm{cm}^2$, the solution temperature from 3$0^{\circ}C$ to 6$0^{\circ}C$, pH from 12.0 to 9.0, agitation speed from 0 rpm to 3200rpm and Au concentration from 10g/1 to 14 g/1, local Au concentration near the cathodic surface increased. With increasing the Au concentration, the surface morphology chanced from porous structure to fine-grained structure. Furthermore, it was observed that the preferred orentation of the Au layer changed from (111) to (220) upon the same variation In the Au concentration. The surface morphology and the preferred orientation of the Au layer were found to be closely related to each other.

• Microbiology and Biotechnology Letters
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• v.11 no.1
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• pp.5-13
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• 1983

This experiment was carried out to elucidate the thermotolerant properties of a thermophilic bacterium which isolated from soils of the hot springs area and selected for the $\beta$-galactosidase production. Biochemical and physiological characteristics of this strain were studied, including the investigation on the fatty acid composition for its neutral fats. The results obtained were summarized as follows. 1. This bacterium was identified as a strain belong to the genus Thermus. 2. Optimal temperature and pH for growth of this strain were $65^{\circ}C$ and pH 6.5 respectively, and it was found to be an absolute thermophilic bacterium which could not grow at 37$^{\circ}C$. 3. No growth was obtained in the medium which contained more than 1.0% of sodium chloride. 4. The tolerable concentration of antobiotics were 10$\mu\textrm{g}$ of penicillin G per $m\ell$ of medium and 0.5$\mu\textrm{g}$ of chloramphenicol per $m\ell$ respectively 5. This strain had autotrophilic requirements for calcium-pantothenate and pyridoxine-HCO as an-essential factor and for niacin as a stimulative factor. 6. Fatty acid composition of neutral fats of the strain was palmitic acid. 60.20%; lauric acid, 11.8%; myristic acid, 7.56%, behenic acid, 4.25%; capric acid, 1.77%; stearic acid, 2.13%; arachidic acid, 1.53%; and others unidentified, 10.7%.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.119-129
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• 2005

The ambient TSP data measured at Seoul, Incheon. Taean, Daegu, Busan in Korea were used to explain the chemical composition and general features of Asian Dust (AD) observed in Korea. 9 episodes out of 19 were sampled from 2000 through May 2002, and measurements were conducted covering ionic and metal components with mass concentration. The results showed that daily averaged mass concentration (TSP) during the AD episodes was 458 $\mu\textrm{g}$/㎥, and ionic and metal concentrations were 27.93 $\mu\textrm{g}$/㎥ and 71.7 $\mu\textrm{g}$/㎥, respectively, accounting for 6.1 % and 15.5% of the total aerosol mass. TSP concentrations during episodes were varied from 120 to 1742 $\mu\textrm{g}$/㎥ according to the impact of Asian Dusts and had a tendency of showing higher values at sites in the west side of Korea, which can be explained by the effect of diffusion and deposition. In this study, ionic components like Ca (NO$_3$)$_2$, CaSO$_4$, NaNO$_3$, Na$_2$SO$_4$ were prominent types in secondary aerosol during AD periods and also indicated that V, Co as well as soil elements such as Ca, Fe, Mg, Mn, K correlated well with Al, while Cu, Cd, Pb, Zn didn't agree well with it. In addition, enrichment factors (EFs) for each metal component were obtained to provide simple information about source contribution of Asian Dust, and the results were compared with those from other AD studies. In this study, the results showed that aerosol properties in Korea during the Asian Dust were considerably different from those of general atmospheric condition and specially varied from case to case rather than site to site, which implies that there are certain variations in the soil of source region, pathways of air mass, and meteorological condition. For the enhanced study, those factors should be combined with the features of Asian Dust resolved from this study.

• Food Science and Preservation
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• v.7 no.4
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• pp.409-413
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• 2000

Previously, the methanolic extracts of thirty Korean medicinal plant seeds were screened for tyrosinase inhibitors using a rapid and simple TLC method, which was superior to a conventional spectrophotometrical in vitro assay. As a result, the methanolic extracts of Thuja orientalis seeds was found to have strong tyrosinase inhibitory activity. To isolate active tyrosinase inhibitors, the seeds were defatted with n-hexane under reflux, and then extracted twice with methanol under reflux at 90$^{\circ}C$. The methanolic extract was evaporated to a small volumn in vacuo, and then successively fractionated with ether, ethyl acetate and n-butanol. The ether extract showing significant tyrosinase inhibitory activity was solubilized with 5% NaHCO$_3$and then acidified with 6N HCI. The ether souble acidic fraction was successively ohromatographed on silica gel, Sephadex LH-20 and preparative TLC. Among four compounds isolated, two of them showed stronger tyrosinase inhibitory activity, comparable to that of L-ascorbic acid (IC$\sub$50/=28$\mu\textrm{g}$/$m\ell$). These results suggest that Thuja orientalis seeds may be useful as potential sources of antibrowning agents in fruits and vegetables, and anti-melanoma agents in cosmetics and phamaceuticals.

• Journal of the Mineralogical Society of Korea
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• v.16 no.1
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• pp.33-47
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• 2003

Various applied-mineralogical characterization including measurements of surface area, size distribution, swelling index, and viscosity were done for some domestic bentonites in order to decipher the rheological properties and their controlling factors. The bentonites, which are Ca-type and relatively low-grade (rnontmorillonite contents: 30 ∼ 75 wt%), occur mostly as subhedral lamellas with the size range of 2 ∼ 4 $\mu\textrm{m}$. The size distribution of mineral fractions in bentonite suspension is dominant in the range of 10 ∼ 100 $\mu\textrm{m}$, and though rather complicated, exhibits roughly bimodal patterns. The feature is more conspicuous in the case of zeolitic bentonite. The bentonites have surface areas ranging 269 ∼ 735 $\m^2$/g, which are measured by EGME adsorption method. The EGME surface areas are nearly proportional to the rnontmorillonite contents, moisture contents, or total CEC. In the surface area measurements, zeolitic bentonites have slightly higher values than those zeolite- free types. The measured swelling index and viscosity of domestic bentonites are comparatively low in values. The swelling values of bentonites were measured to be 250∼500% at maximum by progressively mixing amounts of 2 ∼ 5 wt% Na$_2$CO$_3$, which varies depending on the contents of rnontmorillonite and other impurities, especially zeolite. Much amount of sodium carbonate is required for optimum swelling property of zeolitic bentonited which has usually strong Na- exchanged capacity. The bentonites, which are comparatively feldspar-rich and low in size and crystallinity, tend to be higher in viscosity values. Tn addition, the viscosity is largely higher in case of the bentonites with higher pH in suspension. However, the rheological properties of bentonites such as swelling index and viscosity do not show any obvious relationships with rnontmorillonite contents and mean particle size in suspension. In contrast, roughly speaking, the swelling index of bentonites is reversely proportional to the values of surface area which can be regarded as a collective physico-chemical parameter encompassing all the effects caused by mineral composition, surface charge, particle size, morphological farm, and etc. in bentonites. Thus, the rheological properties in bentonite suspension appear to be rather complicated characteristics which mainly depend on the flocculation of clay particles and the mode of particle association, i.e. quasicrystals, controlled by surface charge, morphology, size, and texture of rnon-tmorillonite, and which partly affected by the finer impurities such as zeolite.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.6
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• pp.665-671
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• 1996

The salt stress at seedling stage of barley was examined in different concentrations of NaCl containing 1/2 Hoagland solution. Among the physiological factors electric conductivity and sodium content of cell sap outflow solution were increased according to the in-crease of NaCl concentration in 1/2 Hoagland solution but the total protein content of root cell sap outflow solution was decreased. Changing pattern of amino acids content in plant was divided into 3 groups which were increased, decreased or unchanged by NaCl concentration in solution. In normal condition, sugar content in plant was higher than potassium or sodium but if NaCl was added more than 25mM in 1/2 Hoagland solution, sodium was the highest. Potassium content in shoot was decreased as 67% of control at 100mM of NaCl containing solution and in root it was decreased as 8%. Sum of the potassium and sodium content in shoot was seriously increased in accordant with NaCl concentration in culture solution, but in root it was gradually decreased. Chlorophyll content per g fresh weight and photosynthetic ability per $\textrm{cm}^2$ in first leaf were not affected by NaCl concentration of 1/2 Hoagland solution but root activity was slightly decreased compared to control.

• Journal of Embryo Transfer
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• v.13 no.3
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• pp.235-243
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• 1998

In this study, we investigated the effects of three kinds of culture medium (Charles and Rosenkrans; CRlaa, Tyrode's; TALP, synthetic oviduct fluid: SOF), insulin transferrin + selenium complex (ITS), macromolecules(polyvinyl alcohol: PVA, fetalb-ovine serum: FBS) and NaCl on the development of early bovine embryos. In experiment 1, there were no differences in embryo development among three kinds of embryo culture medium (CR $l_{aa}$ , TALP, SOF). In experiment 2, BSA, FBS and PVA were added each in TALP as macromolecule sources. The developmental rates of embryos in BSA or FBS added TALP were significantly higher than in PVA added one (p〈0.01), but there was no difference between BSA and FBS added groups. In experiment 3, bovine embryos were cultured in TALP with the following supplements: BSA alone(1, 3 or 8 mg/ml, each) or BSA(1, 3 or 8 mg/ml, each)+ITS (10$\mu\textrm{g}$/m1 insulin, 5 $\mu\textrm{g}$/ml transferrin, 5 ng/ml selenium). In higher concentration of BSA and ITS supplemented groups, the developmental rates over compacted morula were higher than others, but there was a significant effect of ITS only in 1 mg/ml of BSA added group (p〈0.05). In experiment 4, the effect of reduced concentration of NaCl was evaluated. The developmental rate over compacted morula in the medium containing 90 mM of NaCl was higher than in 114 mM group (p〈0.05). In conclusion, BSA could be used as a macromolecule source in bovine embryo culture, and ITS, as a serum substitute, could be used for improving of embryonic development. Also, reduction of NaCl concentration from 114 mM to 90 mM may improve the development of bovine embryos.bryos.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.4
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• pp.232-238
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• 2001

A new DNA purification chip is proposed and fabricated for the sample preparation of Nucleic Acid (NA) probe assay. The proposed DNA purification chip is fabricated using photosensitive glass substrate and polydimethylsiloxane (PDMS) cover fixture. We have successfully captured and eluted the DNA using the fabricated photosensitive glass chip. The fabricated DNA purification chip showed a binding capacity of $15ng/\textrm{cm}^2$and a minimum extractable input concentration of $100copies/200\muL$. The proposed DNA purification chip can be applied for low-cost, disposable sample preparation of NA probe assays.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.275-280
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• 1997

An experimental study to evaluate corrosion protection systems was undertaken with 47 reinforced concrete slab specimens subjected to cyclic wet and dry saltwater exposure. Corrosion measurements included monitoring marcrocell corrosion currents, which are generally accepted in United States practice. Test results indicate that specimens containing 2 kg/$\textrm{m}^3$ of NaCl an exposed to a 10 percent of NaCl show high values of corrosion currents. For the specimens with water repellent membrane currents kept relatively low numerical values, while test specimens with surface corrosion inhibitor hyprotective systems show high values of corrosion currents. No clear indication of the corrosion inhibitor protective systems might be due to the extremely high chloride exposure of the specimens, which has brought the accelerated corrosion. It would be expected that evaluation of the corrosion protective systems need long-term measurement with specimen exposed les chloride but simulating the real condition.