• Journal of the Korean Society for Heat Treatment
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• v.28 no.5
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• pp.229-238
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• 2015

The effects of Sn addition and solution treatment on corrosion behavior were studied in AZ91 magnesium casting alloy. The addition of 5%Sn contributed to the introduction of $Mg_2Sn$ phase, to the reduction in dendritic cell size and to the increase in the amount of secondary phases. After the solution treatment, trace amount of $Al_8Mn_5$ particles were observed in the ${\alpha}$-(Mg) matrix for the AZ91 alloy, while $Mg_2Sn$ phase with high thermal stability was additionally found in the AZ91-5%Sn alloy. Before the solution treatment, the AZ91-5%Sn alloy had better corrosion resistance than the Sn-free alloy, which is caused by the enhanced barrier effect of the (${\beta}+Mg_2Sn$) phases formed more continuously along the dendritic cell boundaries. It is interesting to note that after the solution treatment, the corrosion rate of both alloys became increased, but the Sn-added alloy showed higher corrosion rate than the Sn-free alloy. The microstructural examination on the corroded surfaces revealed that the remaining $Mg_2Sn$ particles in the solution-treated AZ91-5%Sn alloy play a role in accelerating corrosion by galvanic coupling with the ${\alpha}$-(Mg) matrix.

• Korean Journal of Plant Tissue Culture
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• v.27 no.2
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• pp.83-87
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• 2000

To investigate the effect of growth regulators and antioxidant in anther floating cultures of rice, anthers were cultured in liquid media supplemented with different growth regulators, and the effect of antioxidant mixture : (Sigma Chemical Co.) on callus induction and plant regeneration were investigated. N6 medium with 1 mg/L 2,4-D and 1 mg/L kinetin was the best for rice anther floating cultures, which showed 48.5% of callus induction and 6.8% of green plant regeneration. The callus induction was not affected by antioxidant mixture in liquid medium, and antioxidant mixture (250 mg/L) was effective for the reduction of brownish callus and improvement of plant regeneration Antioxidant mixture showed better effectiveness when it was supplemented to both media for callus induction and plant regeneration.

• Journal of Food Hygiene and Safety
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• v.35 no.2
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• pp.189-194
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• 2020

In this study, we investigated the efficacy of Salmonella phage P22 combined with antibiotics to inhibit antibiotic-resistant S. Typhimurium CCARM 8009. The synergistic effect of phage P22 and antibiotics was evaluated by using disk diffusion and broth dilution assays. The development of Antimicrobial resistance was determined after time-kill assay. The antibiotic susceptibility assay showed the inhibition zone sizes around the antibiotic disks were increased up to 78.8% in the presence of phage (cefotaxime; 13.6%, chloramphenicol; 19.3%, ciprofloxacin; 12.7% and erythromycin; 78.8%). The minimum inhibitory concentration values of the combination treatment significantly decreased from 256 to 64 mg/mL for tetracycline, 8 to 4 mg/mL for chloramphenicol, 0.0156 to 0.0078 mg/mL for ciprofloxacin, 128 to 64 mg/mL for erythromycin and 512 to 256 mg/mL for streptomycin. The number of S. Typhimurium CCARM 8009 was approximately 4-log lower than that of the control throughout the combination treatment with phage P22 and ciprofloxacin delete at 37℃ for 20 h. The results indicate that the development of antimicrobial resistance in S. Typhimurium could be reduced in the presence of phage treatment. This study provides promising evidence for the phage-antibiotic combination as an effective treatment to control antibiotic-resistant bacteria.

• Journal of Environmental Health Sciences
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• v.14 no.2
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• pp.1-12
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• 1988

Airborne dust and asbestos fiber concentrations were determined in subway stations located in Seoul area. Two stations, such as Eulchiro 4-Ka Station of Line #2, constructed during a period of 1980-1984 and Hyehwa Station of Line #4, opened in 1985, were selected. The results of the study are as follows. 1. Daily time-weighted average (TWA) concentrations of airborne dusts from 07:00 to 20:00 hours in Line #2 and Line #4 were 0.43$\pm$0.08 mg/m$^3$ and 0.37$\pm$0.12 mg/m$^3$, respectively. Thus, the dust levels in Line #2 were significantly higher than the levels in Line #4 (p < 0.05). 2. Dust levels in the morning (07:00-11:00 hours), noon (11:00-16:00 hours) and in the evening (16:00-20:00 hours) in Line #2 were 0.47$\pm$0.17 mg/m$^3$, 0.37$\pm$0.08 mg/m$^3$, and 0.46$\pm$0.07 mg/m$^3$ respectively. Thus, dust levels in the morning and evening (i.e., during rush hours) were significantly higher than levels in the noon (p < 0.02). However, there was no such difference in dust levels by time in Line #4. 3. Airborne total dust concentrations were well below the occupational health standard of 10 mg/m$^3$, however, the levels were exceeding the ambient air standard recommended by the Korean Environment Administration. 4. All of airborne asbestos fiber concentrations were equal to or below 0.005 fibers/cc. The levels are within both occupational health standards and U.S. EPA criteria. 5. A consideration should be given to the improvements of cleaning methods (such as use of vacuum cleaning instead of brushing) and the existing ventilation (such as more air change and filtration of supply air) for a reduction of dust levels. 6. It is recommended that routine monitoring of airborne dusts and asbestos fibers be conducted because more dusts and asbestos fibers can be produced in the air due to the deterioration of facilities by age and water damage in future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.59-62
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• 1996

Plasma displays (PDP) as a large area wall-hanging display device are rabidly developed with flat CRT, TPT LCD and etc. Especially, AC Plasma Display Panels(AC PDPs) have the inherent memory function which is effective for large area displays. The memory function in AC PDPs is caused by the accumulation of the electrical charge on the protecting layer formed on the dielectric layer. This MgO protective layer prevents the dielectric layer from sputtering by ion in discharge plasma and also has the additional important roll in lowering the firing voltage due to the large secondary electron emission coefficient). Until now, the MgO Protective layer is mainly formed by E-Beam evaporation. With increasing the panel size, this process is difficult to attain cost reduction, and are not suitable for large quantity of production. To the contrary, the methode of shuttering are easy to apply on mass production and to enlarge the size of the panel and shows the superior adhesion and uniformity of thin film. In this study, we have prepared MgO protective layer on AC PDP Cell by reactive magnetron sputtering and studied the effect of MgO layer on the surface discharge characteristics of ac PDP.

• Journal of Life Science
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• v.14 no.1
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• pp.148-153
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• 2004

In this study, we investigated the effect of water, extract of Terminalia Chebula (TC) on physiological activity in mice. TC water extract showed hemagglutination against several different types of red blood cells. $LD_{50}$ of TC extract was 390 mg/kg (po). Treatment of TC water extract orally administered 200, 300 mg/kg daily for one week. Hepatic cytosolic enzymes, xanthine oxidase and aldehyde oxidase activities were significantly increased comparison with normal group. Treatment of TC water extract increased hepatic malondialdehyde (MDA) formation, and reduced glutathione content. We also found that the decreased activities of glutathione S-transferase and glutathione reductase but was not affected activities of $\gamma$-glutamylcysteine synthetase after treatment of TC water extract. These results suggested that increase of the hepatic lipid peroxide is caused by glutathione reduction.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.4
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• pp.479-488
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• 2011

Nanofiltration was performed with polyaluminium chloride solutions at different pH conditions to understand effects of inorganic compounds on aluminum hydrolysis products, i.e., three distinctive groups of aluminum species: polymeric Al at low pH; $Al(OH)_3$ at neutral pH; and ${Al(OH)_4}^-$ at high pH. The PACl solution was prepared to be approximately 4.0mM and adjusted to the designated pH. The influence of inorganic compounds on Al species fouling was investigated with 4.9mM $CaCl_2$ and 3.5mM $MgSO_4$ because $Ca^{2+}$, $Mg^{2+}$, $Cl^-$, ${SO_4}^{2-}$ are the most common inorganics in the drinking water. NF membrane fouling was measured by flux decline rate. The impact of $CaCl_2$ was not significant on the individual Al hydrolysis products fouling. However, the flux decline rate was drastically changed in the presence of $MgSO_4$. The concentration of particulate matters was considerably increased possibly due to interaction between Al species and ${SO_4}^{2-}$ where $MgSO_4$ was introduced. The particulates were accumulated on the membrane and enhanced the hydraulic resistance of the cake layer. In addition, conductivity removal of the membrane was decreased when Al-hydroxide was dominant due to reduction of membrane surface charge. The rejection of $Ca^{2+}$and $Mg^{2+}$ were considerably different, which implys that composition of inorganics paly a role on conductivity removal.

• Korean Journal of Community Nutrition
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• v.17 no.6
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• pp.737-751
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• 2012

The purpose of this study was to assess sodium and potassium intakes and urinary excretion of adults in Busan and to evaluate the relationship of urinary sodium/potassium excretion (UNa/UK) to the status of anthropometric, blood pressure, urine analysis, and nutrient intake of subjects. Nutrient intake by 24-h recall, 24-h UNa/UK were measured with 87 adults aged 20-59 yrs (42 men and 45 women). The mean intakes of sodium and potassium were 3915.4 mg and 3093.9 mg, respectively. The mean 24-h UNa/UK was 3457.0/1680.4 mg. UNa showed significant positive correlations with sodium intake (p < 0.001, p < 0.001), sodium/potassium ratio (p < 0.001, p < 0.01), UK (p < 0.001, p < 0.001), and UNa/UK ratio (p < 0.05, p < 0.01) in men and women and with age, BMI, systolic blood pressure (SBP) and diastolic blood pressure in women (p < 0.05, p < 0.05, p < 0.05, p < 0.05). The UK showed significant positive correlations sodium intake (p < 0.001, p < 0.001), UNa (p < 0.001, p < 0.001) in men and women and with sodium density in men (p < 0.001) and with age, intakes of protein and potassium in women (p < 0.01, p < 0.05, p < 0.05). Mean SBP was lowest in the second quartile and highest in the fourth quartile of UNa. Mean UNa in the second, third, and fourth quartiles were 2821.1 mg, 3621.3 mg, and 5456.4 mg, respectively. Mean SBP in the second, third, and fourth quartiles were 115.8 mmHg, 120.7 mmHg, and 125.9 mmHg, respectively. Based on the results, UNa was related to sodium intake, UK, and SBP. We conclude that nutritional education for the reduction of high sodium intake is needed in the general population to prevent and control adverse blood pressure levels.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.269-274
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• 2014

The purpose of this study is to compare CT (disinfectant concentration * time) values in removing the antibiotic resistance bacteria, antibiotic resistance gene and transfer of antibiotic resistance genes. Different concentration of chlorine(C) and contact time(T) according to the removal of antibiotic resistance was calculated for each. As a result, for the 90% removal of antibiotic resistant bacteria, around 176~353 mg min/L CT values are needed. For the removal of the antibiotic resistance gene, 195~372 mg min/L CT values are required. For the 90% reduction of antibiotic resistance gene transfer by chlorine disinfection, 187~489 mg min/L CT values are needed. Based on our results, higher CT value was required for removing antibiotic resistant genes rather than antibiotic resistance bacteria.

• Microbiology and Biotechnology Letters
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• v.38 no.4
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• pp.405-413
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• 2010

Fig (Ficus carica L.) belongs to the mulberry tree (Moraceae) which is one of the oldest fruits in the world. It has been used as a digestion promoter and a cure for ulcerative inflammation and eruption in Korea. The present study investigated the antimicrobial activity of methanol (MeOH) extract of fig leaves against methicillin-resistant Staphylococcus aureus (MRSA) isolated in clinic. The MeOH extract (MICs, 2.5 to 20 mg/mL; MBCs, 5 to 20 mg/mL) was demonstrated as antibacterial activity in isolates MRSA 1-20. The administration of the MeOH extract in combination with oxacillin or ampicillin induced a reduction of ${\geq}$4-8-fold in all tested bacteria, which was considered to be synergistic based on a FICI of ${\leq}$0.375-0.5. Furthermore, time-kill study was found that a combination of MeOH extract with oxacillin or ampicillin produced a more rapid decrease in the concentration of bacteria CFU/mL than MeOH extract alone. The results suggest that fig leaves could be employed as a natural antibacterial agent in MRSA infection care products.