• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.642-647
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• 2010

This study examined the antimicrobial activity of Myagropsis yendoi (MY). The antimicrobial activity of ethanol and aqueous MY extracts were measured using a paper disc assay. The MY ethanol extract had the best antimicrobial activity. It inhibited the growth of Candida tropicalis and Gram-positive bacteria such as Bacillus subtilis, Listeria innocua, L. monocytogenes, and Staphylococcus aureus at 4 mg/mL. The minimum inhibitory concentration (MIC) of the MY ethanol extract ranged from 0.1 to 0.5%. The MY ethanol extract inhibited the growth of B. subtilis and L. innocuaat concentrations of 0.15% and 0.1%, respectively. The antimicrobial activity of the MY ethanol extract was not affected by heating at $121^{\circ}C$ for 15 min or pH 2.10. Therefore, the main substances responsible for the antimicrobial activity of the MY ethanol extract are believed to be stable with changing heat and pH.

• Journal of the East Asian Society of Dietary Life
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• v.19 no.6
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• pp.981-986
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• 2009

The quality characteristics and antioxidative activity of garlic pickles prepared with persimmon vinegar with or without Maesil (Japanese apricot) juice were investigated. Heat treated garlic cloves ($110^{\circ}C$, 5 min and then rapidly cooling) were salted with NaCl and $CaCl_2$, and then soaked in pickling solution, and stored at $20^{\circ}C$. The pH of the garlic pickles initially ranged from 2.36~3.24, after which the pH slightly increased to 3.22~4.13 during storage, while the acidity was decreased to 1~1.97. Throughout the entire storage periods, the acidity of the garlic pickle containing persimmon vinegar and Maesil was the highest (1.97%). The hardness of the control sample (non heated garlic) decreased during storage, whereas the hardness of all the heat treated groups did not change after 21 days of storage. Moreover, the chewiness of the persimmon vinegar+Maesil group was the highest among the groups. The Hunter color L value of garlic pickles decreased during storage, while the b value (yellowness) increased for all groups except the two persimmon groups. The $IC_{50}$ of the DPPH radical scavanging activity of garlic pickles at 5 day of storage was 85.98~97.81 mg/mL. However, the antioxidative activity of garlic pickles gradually increased with longer storage times. The persimmon vinegar+Maesil group showed the highest antioxidative activity. Results from the sensory evaluation showed that scores of flavor, taste and over-all preference were higher for the persimmon vinegar+Maesil group than the other groups (p<0.05).

• Journal of Microbiology and Biotechnology
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• v.23 no.4
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• pp.451-458
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• 2013

The human gastric pathogen Helicobacter pylori (Hp) has been considered a microaerophile. However, we recently reported that, when supplied with 10% $CO_2$, Hp growth is stimulated by an atmospheric level of $O_2$, suggesting that Hp is a capnophilic aerobe. In this study, we investigated the effects of aerobic $O_2$ tension on Hp cells by comparing gene expression profiles of cultures grown under microaerobic and aerobic conditions in the presence of 10% $CO_2$. The results showed that overall differences in gene expression in Hp cells grown under the two $O_2$ conditions were predominantly growth-phase-dependent. At 6 h, numerous genes were down-regulated under the aerobic condition, accounting for our previous observation that Hp growth was retarded under this condition. At 36 h, however, diverse groups of genes involved in energy metabolism, cellular processes, transport, and cell envelope synthesis were highly up- or down-regulated under the aerobic condition, indicating a progression of the cultures from the log phase to the stationary phase. The expression of several oxidative stress-associated genes including tagD, katA, and rocF was induced in response to aerobic $O_2$ level, whereas trxA, trxB, and ahpC remained unchanged. Altogether, these data demonstrate that aerobic $O_2$ tension is not detrimental to Hp cells but stimulates Hp growth, supporting our previous finding that Hp may be an aerobic bacterium that requires a high $CO_2$ level for its growth.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.4
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• pp.174-178
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• 2005

Destruction of marine ecology system induced by the bal last water discharged from ships is one of the most serious problem among the various ship associated environmental impacts. International Maritime Organization (IMO) has actively dealt with this problem for a long time and is going to start to activate very strong international treatment for preventing ocean from such serious environmental impact. Various technologies of ballast water treatment are now being developed all over the world. In this paper, recent trend of existing ballast water treatment technologies is investigated in detail. Furthermore, in order to apply electrolysis technology to ballast wale r treatment, its basic principle is reviewed theoretically and its feasibility is checked through some in-situ experiments. Quite good results are shown in the experiments enough to confirm its applicability in ballast water treatment.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.3051-3058
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• 2022

In the present work, untreated Iraqi sand with grain sizes varied between 100 and 200 ㎛ was used to produce a colored glass sample that has shielding features against the low gamma-ray energy. Therefore, a weight of 70-60 wt % sand was mixed with 9-14 wt% B₂O₃, 8-10 wt% Na₂O, 4-6 wt% of CaO, 3-6 wt% Al₂O₃, in addition to 0.3% of Co₂O₃. After melting and annealing the glass sample, the X-ray diffraction spectrometry was applied to affirm the amorphous phase of the fabricated glass samples. Moreover, the X-ray dispersive energy spectrometry was used to measure the chemical composition, and the MH-300A densimeter was applied to measure the fabricated sample's density. The Makishima-Makinzie model was applied to predict the mechanical properties of the fabricated glass. Besides, the Monte Carlo simulation was used to estimate the fabricated glass sample's radiation shielding capacity in the low-energy region between 22.1 and 160.6 keV. Therefore, the simulated linear attenuation coefficient changed between 10.725 and 0.484 cm^-1, raising the gamma-ray energy between 22.1 and 160.6 keV. Also, other shielding parameters such as a half-value layer, pure lead equivalent thickness, and buildup factors were calculated.

• Korean Journal of Agricultural Science
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• v.49 no.3
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• pp.629-641
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• 2022

This research was conducted to secure fundamental data for development of a recirculating hydroponic system. To achieve this, Lycopersicum esculentum var. 'Dafnis' and 'TY Tiny' were grown with Yamazaki hydroponic solution and the inorganic element concentrations of plant leaves and nutrient solution of supplied and drained were analyzed periodically. The T-N and P contents in both varieties of tomato leaves showed gradual decreasing tendencies with the passage of time. The 'TY Tiny' tomato had higher contents of those two nutrients than 'Dafnis' tomato in the late stage. The K content of 'Dafnis' tomato was high in the early growth stage, but low in the late stage. However, that of 'TY Tiny' tomatoes rose in the late stage. The Ca content gradually increased in both varieties of tomato in the latter stages. The EC of the drained nutrient solution in both varieties of tomato showed increasing tendencies as time had passed, but the pH was get lowered in the drained solution. The concentrations of NO₃-N, K, Ca, Mg, Na, Fe, and B, except PO₄-P in the drained nutrient solution were generally higher than those in the supplied solution, especially in the period of October through December. The above results can be used for controlling of nutrient concentrations in the recirculated hydroponic cultivation of tomato.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.1
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• pp.1-8
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• 2010

To investigate the effects of sediments on the water quality of an estuary reservoir, Asan reservoir, we analyzed physical and chemical characteristics of the sediments and estimated nutrients release rate from the sediments. The sediments characterized as sandy loam are mainly composed of Nonapatite-P(64.7%) which has strong influence on the eutrophication of the reservoir by releasing from the sediments under the condition of increasing pH and anaerobic environment. High nutrient release rates was observed in April. Negative release rates in June show that there is no significant nutrient release from the sediments. The nutrient release was active at the Site B around the confluence of tributary compared to the Site A near the embankment. Based on the information of nutrient release rates and sediments surface area, daily average nutrient release rates of Asan reservoir are estimated; TN 6,609 kg/d, TP 3,877 kg/d. Since the amount of N and P released from the sediments corresponds to the 7.06% of N and 22.04% of P incoming from the watershed, it can be concluded that there is little influence of sediments on the water quality of Asan reservoir.

• The Korean Journal of Mycology
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• v.41 no.1
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• pp.21-27
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• 2013

This study was carried out to investigated optimum mixing ratio of Korean natural Acer tegmentosum for production of functional oyster mushroom. Total nitrogen and carbon sources of Acer tegmentosum were 0.2% and 44.4%, respectively and C/N ratio was 234. Total nitrogen source and pH of substrate mixed with Acer tegmentosum were 2.7~2.9 and 4.8~5.0, respectively. The contents of $P_2O_5$, $K_2O$ and MgO at Acer tegmentosum media were higher than that of the control. Mycerial growth was the fastest at Acer tegmentosum 10%, and slower by increase of Acer tegmentosum substrate. Yields of fruiting body was the highest to 159 g/850 mL at 10% of Acer tegmentosum and dimeter and thick of pileus were the highest, too. The L value of pileus and stipes were decreased by increase of Acer tegmentosum substrate, but there was no significant difference in the a-value and the b-value. The contents of $P_2O_5$ and $K_2O$ of fruiting body were increased at Acer tegmentosum substrate, but there was no significant difference in contents of CaO, MgO and $Na_2O$.

• Korean Journal of Food Science and Technology
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• v.50 no.1
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• pp.76-82
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• 2018

This study evaluated the physicochemical properties of a novel black bean milk yogurt made by lactic acid producing bacteria isolated from vinegar (Bacillus acidiproducens, BA) and kimchi (Lactobacillus plantarum, LP). Commercially available Lactobacilli mixture for yogurt (YF) were regarded as control bacteria. To investigate optimal conditions to make black bean yogurt, different types of bacteria (BA and LP) and dilution ratios of black bean milk and water (1:1, 1:1.5, and 1:2) were used. Titratable acidity and pH were affected by these dilution ratios, but not by the different types of Lactobacilli used. Titratable acidity and pH were lowest in the 1:1 diluted sample. The visible cell count, sugar content, and viscosity were significantly higher in the sample containing the black bean milk: water ratio of 1:1 than the rest of the samples. In the sensory test, black bean yogurt made with BA showed a higher overall acceptability score, similar to yogurt made with YF. In conclusion, black bean yogurt made by fermentation with BA and with 1:1 black bean milk:water dilution ratio was better than ones made with LP and at other dilution ratios.

• Korean Journal of Poultry Science
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• v.35 no.2
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• pp.171-176
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• 2008

Animal welfare advocates, claim that the induced molting by fasting be avoided. This study was conducted to evaluate the effect of molting induced by various feeding methods on productivity and egg quality in laying hens. We used 400 flocks of 60-week-old leghorn laying hens in four treatments(five replicates of 20 hens each): fasting method (C), feeding single corn grain diet (T1), feeding single wheat bran diet (T2) and feeding single alfalfa meal diet (T3). As the result of the experiment, egg production and daily egg mass significantly decreased only in T1 compared with the control during the $1{\sim}4th$ week after the secondary egg laying (P<0.05). Although the amount of feed intake was significantly less in T1 group during the $1{\sim}4th$ week compared to the control, no significant difference was detected during the total period (P>0.05). In addition, no significant difference of feed conversion was observed between treatment groups. In terms of egg quality, the egg shell thickness was significantly improved in T1 group than the control group by feeding only corn at the 10th and 14th week after the secondary egg laying (P<0.05), but the significant decrease was observed at the corn (T1) and wheat bran (T2) fed treatment groups than the control group at the 26th week of the experiment (P<0.05). The eggshell strength and haugh unit did not show any difference by the molting methods. Egg yolk color was significantly decreased in T1 and T2 group than the control group at the 6th week (P<0.05). However, T1 and T2 group resulted to show significantly high egg yolk color at the 18th week of the experiment (P<0.05). As the result of the experiment, no large difference was observed in the productivity by the feeding molting method and by the fasting induced molting method. In addition, the single diet fed feeding induced molting method by using alfalfa revealed to show more satisfactory trend than the corn or wheat bran single diet fed feeding induced molting methods even if no statistically significant difference was found in terms of egg productivity.