• The Korean Journal of Food And Nutrition
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• v.30 no.4
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• pp.823-829
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• 2017

To increase the shelf-life of strawberry, samples were treated with two gel packs containing slow-released chlorine dioxide ($ClO_2$) gas at 3~5 ppm for 6 days at room temperature and the changes in the major chemical components (ascorbic acid, polyphenols, flavonoids and anthocyanin) contents and antioxidative activities (DPPH, ABTS radical scavenging and metal chelating activity) were investigated. The content of ascorbic acid of control was 40.38 mg% and contained 35.67~44.75 mg% during 6 days. There was no tendency to increase or decrease during storage period. The contents of ascorbic acid of control and 3~5 ppm $ClO_2$ gas treated samples were not significantly different during storage period. The content of polyphenol compounds of initial stage was 111.23 mg% and contained 117.78~132.40 mg% during 6 days. The contents of polyphenol compounds of 3~5 ppm $ClO_2$ gas treated samples were 103.51~130.25 mg%. There were no significant different between them during storage. The flavonoids and anthocyanin contents were not different from the control during storage period regardless of 3~5 ppm $ClO_2$ gas treatment. Furthermore, antioxidative activities were not different among the control and $ClO_2$ gas treatments during storage.

• Nano
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• v.13 no.11
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• pp.1850127.1-1850127.13
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• 2018

Bi metal deposited on $Bi_2MoO_6$ composite photocatalysts have been successfully synthesized via a simple reduction method at room temperature with using $NaBH_4$ as the reducing agent. The photocatalytic activity of the composite was evaluated by degradation of rhodamine B (RhB) and bisphenol A (BPA) solution under visible light. The rate constant of $Bi/Bi_2MoO_6$ composite to RhB is 10.8 times that of $Bi_2MoO_6$, and the degradation rate constant of BPA is 6.9 times of that of $Bi_2MoO_6$. Nitrogen absorption-desorption isotherm proved that the increase of specific surface area is one of the reasons for the improvement of photocatalytic degradation activity of $Bi/Bi_2MoO_6$ composites. The higher charge transfer efficiency of $Bi/Bi_2MoO_6$ is found through the characterization of the photocurrent and impedance, which are attributed to the surface plasmon resonance (SPR) effect produced by the introduction of the metal Bi monomer in the composite. Free radical capture experiments proved that cavitation is the main active species. Based on the above conclusions, a possible mechanism of photocatalytic degradation is proposed.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.4
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• pp.405-411
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• 2020

Objectives: The objectives of this study were to investigate whether airborne fibers were released to the outside air from the asbestos removal area in buildings, and to confirm the existence of asbestos fibers in samples using transmission electron microscopy(TEM). Methods: A total of 1,295 samples was collected from inside and outside 155 asbestos removal areas. To investigate the release of asbestos fibers from the removal area, samples were collected at three locations, such as an entrance to change room, an exit of negative pressure unit(NPU) and perimeter areas. Samples were also collected in the removal area prior to and after removal activity. All samples were analyzed by phase contrast microscopy(PCM) and one-tenth of the samples was analyzed using TEM to discriminate asbestos fibers. Results: During the asbestos removal activity, 27(4.1%) of 662 samples collected outside the removal area showed airborne fiber concentrations equal to or in excess of 0.01 f/cc, the permissible emission standard of the Korean Ministry of Environment. Further, 111 samples were analyzed using TEM. The distribution of asbestos fiber concentrations was log-normal. It was found that 51 of 111 samples(46%) contained asbestos fibers. Conclusions: There is a potential risk of asbestos exposure among neighbors and the public outside the asbestos removal areas. It is recommended that the asbestos removal work be conducted strictly following the specifications required by government and/or professional organizations.

• Journal of the Korean Society of Food Culture
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• v.37 no.6
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• pp.519-528
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• 2022

The Cheonggukjang used in this study was made with four soybean cultivars grown and harvested at the National Agrobiodiversity Center of the National Academy of Agricultural Sciences: C1 (KLS87248), C2 (Nongrim 51), C3 (GNU-2007-14613), and C4 (Daewon). The soybeans were inoculated with Bacillus subtilis AFY-2 and fermented for 0, 12, 21, 36, 45, and 60 h in a culture room at 35℃. ABTS and DPPH radical scavenging activities were significantly increased upon fermentation for 12 hours in all samples and maintained or decreased after 21 hour The inhibition of NO production was significantly increased compared to the LPS-treated group, and the C2 sample showed inhibition of NO production at 12 hours of fermentation, and the C3 sample showed inhibition at 21 hours of fermentation. PCA analysis revealed that the ABTS and DPPH radical scavenging activity and NO production inhibitory activity reached peak levels around 12 h fermentation time for all samples. Our results indicate that the optimal fermentation time of the Cheonggukjang sample is 12 hours, confirming the high correlation of all experiments.

• The Korea Journal of Herbology
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• v.32 no.3
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• pp.29-36
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• 2017

Objectives : In order to investigate the possibility of Sorbus commixta Heal. stem (SC) as a natural material, antioxidant activities of the hot water and ethanol extracts were examined. Methods : The samples of SC were pulverized, and fractions were extracted repeatedly three times from hot water and 70% ethanol at room temperature for 2 hours. The antioxidant activities were analyzed from total polyphenol, flavonoid contents, DPPH, ABTS, hydroxyl radical, $Fe2^+$ chelating, and nitrite scavenging activity. Results : Total polyphenol contents were significantly higher in ethanol extract group ($504.39{\mu}g/m{\ell}$) than in hot water extract group ($364.64{\mu}g/m{\ell}$). Total flavonoid contents were also significantly higher in ethanol extract group ($160.09{\mu}g/m{\ell}$) than in hot water extract group ($124.59{\mu}g/m{\ell}$). DPPH, ABTS, $Fe2^+$ chelating were slightly higher in ethanol extract gorups than in hot water extract groups, and increased in a dose-dependent manner. The hydroxyl radical scavenging activity (18.42~23.61%) of ethanol extract groups were shown to be approximately twice higher than that (7.63~10.37%) of hot water extract groups at $12.5{\sim}50{\mu}g/m{\ell}$ concentration. Nitrite scavenging activities of both ethanol and hot-water extract groups were shown to be higher in a dose dependent manner at the concentration of $12.5{\sim}50{\mu}g/m{\ell}$ at pH 3.0 than at pH 1.2, and ethanol extract groups (86.55~96.64%) had higher activity than the hot water extract groups (42.59~92.63%), which was higher than that of the control group antioxidant BHT (72.96~80.11%). Conclusions : The extracts of SC displayed antioxidant activities which suggested a natural material can be developed to functional material.

• The Korea Journal of Herbology
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• v.32 no.4
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• pp.39-46
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• 2017

Objectives : This study aims to provide basic data about Portulacae Herba (PH) extracts as natural antioxidants by considering diverse antioxidant activities of PH depending on solvents. Methods : The samples of PH were pulverized, and A hot water and a 70% EtOH were stir-extracted for two hours three times repeatedly in a water bath with a temperature of 95 degrees and at room temperature respectively to measure 7 kinds of antioxidant activities. Results : There were significant differences in total phenol content, because the total phenol content of the 70% EtOH extract was higher than the hot water extract's, and the total flavonoid content of the 70% EtOH extract($4.40{\mu}g/mg$) was nearly 3.8 times higher than the hot water extract's($1.16{\mu}g/mg$). DPPH and ABTS radical scavenging activities were 70% EtOH extract showed a little higher activity than the hot water extract, and at a concentration of $500{\mu}g/mg$, the highest scavenging activity was found in the 70% EtOH extract, not in the control group. Hydroxyl radical and $Fe^{2+}$ chelatingactivities were slightly higher in hot water extract than in 70% EtOH extract, and increased in a dose-dependent manner. Nitrite scavenging activities increased dose-dependently in the hot water and the 70% EtOH extract, regardless of the pH level, and scavenging activity of the 70% EtOH extract was higher at pH 1.2 than at pH 3.0. Conclusions : In conclusion, it is thought that PH hot water and 70% EtOH extract have antioxidant activities, and can be used as natural antioxidants in future.

• Mycobiology
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• v.36 no.2
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• pp.102-105
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• 2008

The acetylcholinesterase (AChE) inhibitor of Yarrowia lipolytica S-3 was maximally produced when it was incubated at $30^{\circ}C$ for 36 h in an optimal medium containing 1% yeast extract, 2% peptone and 2% glucose, with an initial pH 6.0. The final AChE inhibitory activity under these conditions was an $IC_{50}$ value of 64mg/ml. After partial purification of the AChE inhibitor by means of systematic solvent extraction, the final $IC_{50}$ value of the partially purified AChE inhibitor was 0.75 mg/ml. We prepared a test product by using the partially purified AChE inhibitor and then determined its stability for the development of a new antidementia commercial product. The test product was stable at room temperature for 15 weeks.

• Tribology and Lubricants
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• v.14 no.2
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• pp.1-9
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• 1998

The electrorheological (ER) behavior of suspensions in silicone oil of phosphated cellulose particles (average particle size 17.77 ${\mu}{\textrm}{m}$) was investigated at room temperature with electric fields up to 2.5 KV/mm. In this paper, for development of anhydrous ER suspensions using at wide temperature range, we would like to know fundamental understandings on the ER activity. As a first step, the anhydrous ER suspensions dispersed the phosphated cellulose particles were measured, and not only the electrical characteristics such as dielectric constant, current density and electrical conductivity but also the rheological properties on strength of electric field and quantity of dispersed phase were studied. From the experimental results, the anhydrous ER suspensions dispersed phosphated cellulose particles showed a stable current density and very high performance of ER effect $(\tau/\tau_0=1030)$ on the 2.5 KV/mm and the dynamic yield stress $(\tau_y)$ was in exponential proportion to the strength of electric fields.

• Toxicological Research
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• v.13 no.1_2
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• pp.55-60
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• 1997

Gamma irradiation was applied to Angelicae gigantis radix and Aloe to improve their hygienic quality. The effective dose of irradiation was 7 kGy in Angelicae gigantis radlx and 5 kGy in Aloe for the sterilization of all contaminated microorganisms tested. After 8 months of storage at room temperature, no growth of microorganisms was observed in the irradiated products. The safety of these products were evaluated by Salmonella typhimurium reversion assay and in vivo micronucleus assay using mouse bone marrow cells. They were negative in the bacterial reversion assay with S. typhimurium TA 98, TA100, TA1535 and TA1537. In the in vivo mouse micronucleus assay, they did not show any clastogenic effect at all doses tested. These results indicate that the gamma irradiation of Angelicae gigantis radix at 12 kGy and of Aloe at 10 kGy have no genotoxic effects under these experimental conditions.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2748-2752
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• 2012

Cr(III) and Co(III) complexes with acetylacetonate were anchored onto a mesoporous MCM-41 through Schiff condensation. The materials were characterized by XRD, FT-IR, BET, CHN and ICP techniques. Elemental analysis of samples revealed that one C=N bond was formed through Schiff condensation on MCM-41 surface. The catalysts were tested for the alcohol oxidations using t-butyl hydroperoxide (TBHP) and $H_2O_2$ as oxidant. The catalytic experiments were carried out at both room temperature and reflux condition. Various solvents such as dichloromethane, acetonitrile and water were examined in the oxidation of alcohols. Among the different solvents, catalytic activity is found more in acetonitrile. Further, the catalysts were recycled three times in the oxidation of alcohols and no major change in the conversion and selectivity is observed, which shows that the immobilized metal-acetylacetonate complexes are stable under the present reaction conditions.