• The korean journal of orthodontics
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• v.30 no.6 s.83
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• pp.723-730
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• 2000

Orthodontic tooth movement requires remodelling of periodontal tissues, especially alveolar bone. Fluoride is known to be a potent inhibitor of osteoclastic bone resorption. The purpose of this study was to examine the effects of a consumption of fluoride on osteoclast numbers appearing on the pressure side of alveolar bones at experimental tooth movement. 40 male rats were exposed to 0, 10, 25 mg/kg/day of sodium fluoride(NaF) in their drinking water for up to 60 days. Orthodontic appliance were activated to mesially tip maxillary first molar with 50-70g. The rats were sacrificed at 1, 2, 4 days after initial activation. The number of osteoclast was counted in a $450\times700\;{\mu}m^2$ area interradicular septum on the pressure side of the maxillary first molar. The results were as fellows, 1. There was significantly different osteoclast number between control group and 25 mg/kg/day group at all measured time. (p<0.05) 2. There was significantly different active bone-resorption area between control group and 25 mg/kg/day group except at 96 hours post activation. (p<0.05) 3. There was slight reduction of active bone- resorption area in control group from 48 hours to 96 hours but in both 10 mg/kg/day group and 25 mg/kg/day group a slight increase was observed from 48 hours to 96 hours.

• Journal of Korean Society of Forest Science
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• v.87 no.4
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• pp.611-619
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• 1998

This study was carried out to examine the effects of soil acidification on growth and nutrient status of 2 - year - old Pious densiflora Sieb. et Zucc. seedlings grown for 120 days in brown forest soils acidified with $H_2SO_4$ solution with or without leaching rations from the soil. The concentrations of A1 in the acidified soils increased with increasing amount of $H^+$ added to the soil. The total dry weight of the seedlings was decreased by the addition of the $H_2SO_4$ solution. The increase of Al concentration in the belowground part resulted from the decreased concentration of essential mineral elements such as Ca and Mg in the aboveground part. In addition, a strong positive correlation(r=0.96, p<0.001) was observed between the dry weight of the seedlings and the molar (Ca+Mg+K)/A1 ratio of the soil solution. When the molar (Ca+Mg+K)/Al ratio was approximately 7.0, the dry weight of the seedlings began to decrease compared with that of the seedlings in the control treatment. The seedlings with the molar (Ca+Mg+K)/Al ratio of 1.0 resulted from approximately 40% growth reduction compared with the control value. The results suggest that the molar (Ca+Mg+K)/Al ratio of the soil solution may be a useful indicator for assessing the critical load of acid deposition.

• Journal of Korea Water Resources Association
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• v.57 no.4
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• pp.277-287
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• 2024

Water distribution system (WDS) is exposed to various water quality incidents during its operation. This study utilized Quantitative Microbial Risk Assessment (QMRA) to analyze the risk associated with potential virus intrusion in WDSs. Additionally, the study determined the location and operation of rechlorination facilities to minimize potential risk. In addition, water quality resilience was calculated to confirm that the chlorine concentration maintains within the target range (0.1-1.0 mg/L) during normal operation. Hydraulic analysis was performed using EPANET, while EPANET-MSX was linked to simulate the reactions between viruses and chlorine. The proposed methodology was applied to the Bellingham network in the United States, where rechlorination facilities capable of injecting chlorine concentrations ranging from 0.5 mg/L to 1.0 mg/L were considered. Results indicated that without rechlorination facilities, the Average risk was 0.0154. However, installing rechlorination facilities and injecting chlorine at a concentration of 1.0 mg/L could reduce the Average risk to 39.1%. It was observed that excessive chlorine injection through rechlorination facilities reduced water quality resilience. Consequently, a rechlorination facility with a concentration of 0.5 mg/L was selected, resulting in a reduction of approximately 20% in average risk. This study provides insights for designing rechlorination facilities to enhance preparedness against potential virus ingress in the future.

• Journal of Nutrition and Health
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• v.50 no.6
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• pp.664-678
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• 2017

Purpose: To identify the effectiveness of policy evaluation, consistent monitoring is necessary. This study aimed to carry out mid-term evaluation of objectives and programs related to comprehensive plans for sodium intake reduction by 2020 for Seoul city and then reestablish the objectives of the sodium intake reduction plans. Methods: Literature reviews, data analysis, and reviews of expert focus-groups were performed to evaluate objectives, to develop a new goal, and to identify the priority subjects of the sodium intake reduction programs. In order to examine target populations for the programs, awareness and behaviors related to sodium intakes among Seoul citizens were examined by sex, age, and income level using the 2008~2013 Korea National Health and Nutrition Examination Survey data. Results: Current objectives of the sodium intake reduction plan by 2020 for Seoul city were not appropriate, so objectives were reset to 3,600 mg of sodium intake by 2020 among Seoul citizens with 2% reduction per year. Although sodium intake showed a decreasing trend by year, it was still high, especially in men. The sodium intake reduction programs currently in progress have not been assessed at multiple levels across multiple sectors and have only been assessed fragmentarily. For dietary behavior related to sodium intakes by sex, age, and income level, sodium intake was higher in the group with less than 100 g of fruit intake compared to the group with 100 g or more. Subjects aged 30~59 years and the low household income group showed relatively higher sodium intakes. Based on the data analysis and the expert review, the priority subject of the sodium intake reduction programs was determined to be adult men. In terms of a program strategy for sodium intake reduction, multi-level and setting approaches, including work sites, home, and restaurants, were suggested to reduce sodium intakes of the target subject. Conclusion: The suggested objectives should be consistently monitored by data analysis, and the determined programs need to be phased in over 5 years.

• Journal of Environmental Science International
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• v.7 no.3
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• pp.409-413
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• 1998

Polyamine was synthesized for the drinking water treatment. Polyamine was produced by the two step polycondensation of dimethytamine(DMA) and epichlorohydrin(EPI) and its properties were characterized. The effects of mole ratio of (DMA1/1EPl), reaction temperature and reaction time on synthesis of polyamine were investigated. Polyamine flocculant was applied to Nak-dong river raw water to examine its efficiency in reducing turbidity. The synthesized polyamine was effective as flocculant for drinking water treatment. The addition of 1 mg/L of polyamlne flocculant caused the reduction of 50% PAC (polyaluminium chloride).

• Proceedings of the Korean Vacuum Society Conference
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• 2006.02a
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• pp.142-142
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• 2006

• Proceedings of the Plant Resources Society of Korea Conference
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• v.18 no.1
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• pp.52-60
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• 2005

The objectives of present study were to investigate the hepatoprotective and antioxidative effects of onion extracts. Primary cultures of rat hepatocytes were incubated with 1.5 mM tert-butyl hydroperoxide(t-BHP), potent oxidizing agent for liver injury for 1 hr in the presence or absence of various concentrations (0, 0.01, 0.05, 0.1 or 0.3 mg/ml) of onion extract. Cytotoxicity and cell viability were determined by measuring glutamic oxaloacetic transaminase(GOT) activity, lactate dehydrogenase(LDH) activity and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) value. Lipid peroxidation was evaluated using thiobarbituric acid reactive substances(TBARS) assay. Effects on antioxidant system were determined by measuring catalase, glutathione peroxidase(GSH-Px), glutathione reductase(GSH-Rd) activities as well as DNA strand breaking assay. Incubation with t-BHP alone increased GOT and LDH activities and TBARS concentration but decreased MTT reduction. Onion extracts at the concentration of 0.05 mg/ml began to decrease GOT and LDH activities induced by 1.5 mM t-BHP. Decreased MTT reduction began to be increased by onion extract at the concentration of 0.01 mg/ml. Onion extracts at the concentration of 0.01 mg/ml began to decrease TBARS concentration induced by t-BHP. Taken together, onion extracts prevented t-BHP-induced hepatocyte injury and lipid peroxidation. Catalase, GSH-Px and GSH-Rd activities of hepatocytes were significantly decreased by 1.5 mM t-BHP for 1 hr incubation. Onion extracts, on the other hand, at the concentration of 0.1 mg/ml began to prevent t-BHP-induced decrease in catalase, GSH-Px and GSH-Rd activities. Onion extracts prevented hydroxyl radical-induced single-strand breakage in dose-dependent manner when plasmid DNA was incubated with various concentrations of onion extracts in the presence of Fenton regents producing hydroxyl radical. These results demonstrate that onion extracts suppressed t-BHP-induced cytoctoxicity, decreased viability and lipid peroxidation and increased GSH-Px, GSH-Rd and catalase activities. Thus hepatoprotective and antioxidant effects of onion extract seem to be due to, at least in part, the increase in antioxidant enzyme activities as well as prevention from hydroxyl radical-induced oxidation, followed by inhibition in lipid peroxidation.

• Journal of the Korean Applied Science and Technology
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• v.37 no.2
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• pp.153-161
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• 2020

Arthrospira platensis is the oldest marine microalgae on the planet, is said to contain most of the nutrients needed by the human body. It's components are reported to contain a large amount of various substances such as phycocyanin, chlorophyll and β-carotene, and are known to have an aging and whitening effect. In this study, UVB-induced reactive oxygen species reduction efficacy and antioxidant activity of spirulina purified water extract were investigated. effect was confirmed by measuring DPPH radical scavenging activity, FRAP reducing power and ABTS⁺ radical scavenging activity of 0.05, 0.10, 0.50 1.0 mg/mL of spirulina purified water extract. The coagulation rate, hatching rate and heart rate toxicity were measured by treating spirulina purified water extract with 0.05, 0.10, 0.50 mg/mL concentration using Zebrafish, an alternative experimental animal model. UVB-induced ROS measurement was treated with spirulina extract at 0.05, 0.10, 0.50 mg/mL concentration, and then stained with DCFH-DA to confirm the inhibitory effect of ROS. As a result of measuring antioxidant effect, DPPH, FRAP and ABTS⁺ showed concentration-dependent antioxidant effects in comparison with ascorbic acid. and measuring the coagulation rate, hatching rate, and heart rate using Zebrafish, an alternative experimental animal, it was confirmed that there was no toxicity in 0.05 and 0.10 mg/mL except 0.5 mg/mL compared to the control group. The ROS scavenging activity of UVB-induced zebrafish showed higher ROS reduction than the positive control. The results of this study suggest that spirulina and purified water extracts are valuable for UV and skin protection cosmetics.

• Korean Journal of Plant Resources
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• v.18 no.3
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• pp.470-478
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• 2005

The objective of present study was to investigate the hepatoprotective and antioxidative effects of onion extracts. Primary cultures of rat hepatocytes were incubated with 1.5 mM tort-butyl hydroperoxide(t-BHP), potent oxidizing agent to liver, for 1 hr in the presence or absence of various concentrations (0, 0.01, 0.05, 0.1 or 0.3 mg/ml) of onion extract. Incubation with t-BHP increased glutamic oxaloacetic transaminase(GOT) and lactate dehydrogenase(LDH) acitivities and thiobarbituric acid reactive substances(TBARS) concentration but decreased 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) reduction. Onion extracts at the concentration of 0.05 mg/ml decreased t-BHP-induced GOT and LDH activities. Onion extract at the concentration of 0.1 mg/ml increased t-BHP-induced MTT reduction. Onion extract at the concentration of 0.01 mg/ml decreased t-BHP-induced TBARS concentration. Taken together, onion extracts prevented t-BHP-induced hepatocyte injury and lipid peroxidation. Catalase, glutathione peroxidase(GSH-Px) and glutathione reductase(GSH-Rd) activities of hepatocytes were significantly decreased by t-BHP. Onion extracts at the concentration of 0.1 mg/ml prevented t-BHP-induced decrease in catalase, GSH-Px and GSH-Rd activities. Onion extracts prevented hydroxyl radical-induced single-strand breakage in dose-dependent manner when plasmid DNA was incubated with various concentrations of onion extracts in the presence of Fenton reagents producing hydroxyl radical. These results demonstrate that onion extracts suppressed t-BHP-induced cytoctoxicity, decreased viability and lipid peroxidation and increased GSH-Px, GSH-Rd and catalase activities. Thus hepatoprotective and antioxidant effects of onion extract seem to be due to, at least in part, the increase in antioxidant enzyme activities as well as prevention from hydroxyl radical-induced oxidation, followed by inhibition of lipid peroxidation.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.353-360
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• 2016

Effect of heavy metals(Cd, Cu, Zn) on the survival and population growth rates(PGR) of marine rotifer, Brachionus plicatilis were examined. B. plicatilis were exposed to Cd, Cu and Zn for 24 h to determine their survival and 72 h to determine their PGR. Survival rates in the control groups were greater than 90%. They were decreased with increasing concentrations of Cd, Cu and Zn. Survival rates were reduced in a concentration-dependent manner. Significant reduction in survival rates after exposure to Cd, Cu and Zn at concentration greater than 40.00, 0.13 and $10.00mg\;L^{-1}$, respectively. PGR in the control groups were greater than 0.50. They were decreased with increasing concentrations of heavy metals. PGR were reduced in a concentration-dependent manner. Significant reduction in PGR after exposure to Cd, Cu and Zn occurred at concentration greater than 12.5, 0.06 and $1.00mg\;L^{-1}$, respectively. The order of heavy metal toxicity based on PGR was Cu>Zn>Cd, with $EC_{50}$ (50% Effective Concentration) values of 0.12, 6.15 and $21.41mg\;L^{-1}$, respectively. The lowest-observed-effective-concentrations(LOEC) of PGR after exposure to Cd, Cu and Zn were 12.50, 0.06 and $1.00mg\;L^{-1}$, respectively. The No-observed-effective-concentrations(NOEC) of PGR after exposure to Cd, Cu and Zn were 6.25, 0.03 and $0.01mg\;L^{-1}$, respectively, in marine ecosystems have toxic effects on PGR of B. plicatilis. These results suggest that the PGR of B. plicatilis are useful tool to assess the effect of heavy metals on primary consumers in marine natural ecosystems.