• The korean journal of orthodontics
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• v.34 no.3 s.104
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• pp.253-260
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• 2004

Frictional force between the orthodontic bracket and arch wire during sliding tooth movement is related to many factors, such as the size, shape and material of both the bracket and wire, ligation method and the angle formed between the bracket and wire. There have been clear conclusions drawn in regard to most of these factors, but as to the effect of bracket width on frictional force there are only conflicting studies. This study was designed to investigate the effect of bracket width on the amount of frictional forces generated during clinically simulated tooth movement. Three different widths of brackets $(0.018{\times}0.025'\;standard)$ narrow (2.40mm), medium (3.00mm) and wide (4.25mm) were used in tandem with $0.016{\times}0.022'$ stainless steel wire. Three bracket-arch wire combinations were drawn on for 4 minutes on a testing apparatus with a head speed of 0.5mm/min and tested 7 times each. To reproduce biological conditions, dentoalveolar models were designed with indirect technique using a material with similar elastic properties as periodontal ligament (PDL). In addition, to minimize the effect of ligation force, elastomer was used with added resin, which was attached to the bracket to make up for the discrepancies of bracket width. The results were as follows: 1. Maximum frictional force for each bracket-arch wire combination was: Narrow (2.40mm): $68.09\pm4.69gmf$ Medium (3.00mm): $72.75\pm4.98 gmf$ Wide (4.25mm): $72.59\pm4.54gmf$ 2. Frictional force was increased with more displacement of wire through the bracket slot. 3. The ANOVA psot-hoc test showed that the bracker width had no significant effect on frictional force when tested under clinically simulated conditions(p>0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.2
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• pp.262-274
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• 1999

Several alternatives for increasing the fluoride concentration in the mouth, such as water fluoridation, ingestion of fluoride supplements, fluoride paste, fluoride mouthrinse, application of fluoride gel are available. There is an impressive body of evidence that the topically deliverd fluorides are clinically effective in inhibiting the progression of dental caries. Recent studies on the cariostatic action of fluoride have indicated the importance of fluoride in the fluid environment of the teeth. The fluoride levels in unstimulated whole saliva can be considered indicative of F in the aqueous phase available for interaction with the tooth surface at a given time. The retention of F in the mouth after topical fluoride treatment is considered to be an important factor in the clinical efficacy of F. The aim of this study was to determine the elevation and clearance of fluoride in whole saliv after the following topical flouride treatments using HMDS-diffusion technique and fluoride ion electrode. The obtained results were as follow: 1. Average salivary fluoride concentration in the unstimulated whole saliva was $0.0152ppm{\pm}0.0091ppm$. Unstimulated salivary flow rate was between 0.34-0.36ml/min and there was no statistically significant difference among the groups(p>0.05). 2. Except for the immediate time after treatment, fluoride levels followed as APF gel>neutral gel>F-rinse>F-paste. There was no statistical difference between the salivary F concentration of F-paste group and that of control group after 2 hours. In case of F-rinse group, after 3 hours the concentration had dropped to baseline value. But there was statistically significant difference among the F concentraion of F gel groups and that of control group(p<0.05). 3. The mean $AUC_{0-120min}$ values were followed as neutral gel>APF gel>F-rinse>F-paste, and the values of the two former groups were significantly higher than those of the two latter groups(p<0.05).

• Journal of Aquaculture
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• v.6 no.1
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• pp.29-46
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• 1993

In order to determine the optimum digestible energy to protein (DE/P) ratio in diets for Korean rockfish, Sebastes schlegeli, $45\%$ and $40\%$ protein diets with graded levels of DE/P ratio were fed to average 36g and 80g fish, respectively. The DE/P ratios in the $45\%$ protein diets ranged from 7.4 to 10.0 kcal/g protein, while those in the $40\%$ protein diets varied between 7.5 and 8.9 kcal/g protein. Both in the $45\%$ and $40\%$ protein diets, the changes in the DE/P ratios did not affect either the daily weight gain or the feed efficiency. However daily protein retention, daily energy retention, nutrient utilization and chemical composition in carcass varied depending on the DE/P ratios. Thus based on these parameters as criteria, the optimum DE/P ratio for both the $40\%$ and $45\%$ protein diets, estimated to be about 8 kcal/g protein. DE/P ratios more than 8 kcal/g protein, led to the deposition of a large amount of body fat, especially in the viscera. Any protein-sparing effect was not observed with the increase of the energy content in the diets. Apparent digestibility coefficients determined by the indirect method, using $Cr_2O_3$ as an indicator, were around $90,\;98\%\;and\;70\%$, for protein, lipid and digestible carbohydrate respectively, without any distinct differences between the diets.

• Korean Journal of Weed Science
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• v.3 no.1
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• pp.39-49
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• 1983

By use of three paddy rice lines as the near-isogenic in plant type (Broom, Open, and Spread type in tillering angle), the interspecific competition patterns of rice plants with three important weed species (Cyperus serotinus, Eleocharis kuroguwai, and Potamogeton distinctus) under the three densities of weed standing (0.25 and 50 percent of the rice plants), were observed. Under the experimented conditions, paddy yields were varied more significantly with weed competition descriptions than with plant types of paddy rice. And spread typed rice was more competitive to the detected weed species, however, the broom and spread typed rice were to Potamogeton SP, among others. The result of the clustering analysis of crop-weed competition patterns, estimated by 1-Q mode correlation coefficients, indicated that the first-order component affecting the competition patterns of crop-weed was rather the plant types of rice than either weed species or weed standing densities.

• Korean Journal of Medicinal Crop Science
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• v.10 no.3
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• pp.222-229
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• 2002

Ixeris dentata root were extracted with methanol and then fractionated with n-hexane, EtOAc and BuOH to get active fractions. and their antioxidant and antimicrobial activities in each fraction were determined. Ethyl acetate fraction of Ixeris dentata root showed strong antioxidant activities, but aqueous fraction did not show any activities. But in the antimicrobial test, aqueous fraction showed strong antimicrobial activities except to Escherichia coli. especially, aqueous fraction showed the strongest activities against Hypocrea nigricans. and butanol fraction showed the strongest activities against Cladosporium herbarum. This study was performed to determine the antimutagenic and cytotoxic effect of Ixeris dentata root methanol extract on Salmonella typhimurium TA98, TA100 and cancer cell lines using ames test and cytotoxicity assay, respectively. Cancer cell lines include human lung carcinoma(A549), human breast adenocarcinoma(MCF-7) and human hepatocellular carcinoma (Hep 3B). Futher fractionations with hexane, ethyl acetate, butanol and water from methanol extract of Ixeris dentata root were performed to obtain effective fraction, methanol extracts showed 79.94% inhibitory effect on the mutagenesis induced by N' -methyl- N' -nitro-N-nitrosoguanidine(MNNG) against TA100, while 89.99% inhibition was observed on the mutagenesis induced by 4-nitroquinoline-1-oxide(4NQO) against TA98. In the meanwhile, butanol fraction showed 89.92% and 71.01% inhibitory effect on the mutagenesis induced by benzo(a)pyrene(B(a)P) against TA98 and TA100, respectively. Ethyl acetate fraction showed the strongest effect against A549, MCF-7 and Hep3B at the same concentration compared to those of other fration.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.4
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• pp.358-383
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• 2015

The concept of 'carbon footprint' has been developed as a means of quantifying the specific emissions of the greenhouse gases (GHGs) that cause global warming. Although there are still neither clear definitions of the term nor rules for units or the scope of its estimation, it is broadly accepted that the carbon footprint is the total amount of GHGs, expressed as $CO_2$ equivalents, emitted into the atmosphere directly or indirectly at all processes of the production by an individual or organization. According to the ISO/TS 14067, the carbon footprint of a product is calculated by multiplying the units of activity of processes that emit GHGs by emission factor of the processes, and by summing them up. Based on this, 'carbon labelling' system has been implemented in various ways over the world to provide consumers the opportunities of comparison and choice, and to encourage voluntary activities of producers to reduce GHG emissions. In the agricultural sector, as a judgment basis to help purchaser with ethical consumption, 'low-carbon agricultural and livestock products certification' system is expected to have more utilization value. In this process, the 'cradle to gate' approach (which excludes stages for usage and disposal) is mainly used to set the boundaries of the life cycle assessment for agricultural products. The estimation of carbon footprint for the entire agricultural and forestry sector should take both removals and emissions into account in the "National Greenhouse Gas Inventory Report". The carbon accumulation in the biomass of perennial trees in cropland should be considered also to reduce the total GHG emissions. In order to accomplish this, tower-based flux measurements can be used, which provide a direct quantification of $CO_2$ exchange during the entire life cycle. Carbon footprint information can be combined with other indicators to develop more holistic assessment indicators for sustainable agricultural and forestry ecosystems.

• Clinical and Experimental Pediatrics
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• v.49 no.11
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• pp.1216-1222
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• 2006

Purpose : Though atopic and nonatopic asthma have different clinical manifestations, bronchial hyperresponsiveness (BHR) and airway inflammations are common characteristics of them. We investigated BHR to both methacholine and adenosine 5'-monophosphate (AMP), and their relationships with blood eosinophil markers in nonatopic asthma as well as atopic asthma. Methods : We studied 116 children (82 atopics; 34 nonatopics) with mild to moderate asthma. Methacholine and AMP challenge tests were performed and bronchial responsiveness was expressed as $PC_{20}$ (provocative concentration causing a 20 percent fall in $FEV_1$); blood eosinopil counts (ETCs) and serum eosinophil cationic protein (ECP) levels were gauged. Results : In atopics, 95.1 percent and 90.2 percent showed hyperreactivity to methacholine ($PC_{20}$<16 mg/mL) and AMP ($PC_{20}$<200 mg/mL), respectively. Meanwhile, in nonatopics, 94.1 percent and 52.9 percent displayed hyperreactivity to methacholine and AMP, respectively. The geometric mean of AMP $PC_{20}$ was lower in atopics (31.6 mg/mL) than in nonatopics (125.9 mg/mL); that of methacholine $PC_{20}$ was similar in the two groups. AMP $PC_{20}$ correlated with blood ETCs in both atopics(r=-0.30, P<0.01) and nonatopics (r=-0.57, P<0.01), and correlated with serum ECP levels (r=-0.23, P<0.01) in atopics, but not in nonatopics. Apart from AMP, methacholine $PC_{20}$ was not associated with blood eosinophil markers in either group. Conclusion : Atopics more frequently displayed BHR to AMP than nonatopics. Furthermore, BHR to AMP was associated with not only blood ETCs, but serum ECP levels in atopics but was correlated with only blood ETCs in nonatopics. Those results suggest that BHR to AMP reflects airway inflammation in asthma and is more related to atopy.

• Journal of the Korea Concrete Institute
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• v.25 no.3
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• pp.321-329
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• 2013

Recently, the medium-low level radioactive waste from nuclear power plant must be transported from temporary storage to the final repository. Medium-low level radioactive waste, which is composed mainly of the liquid ion exchange resin, has been consolidated with cementitious material in the plastic or iron container. Since cementitious material is brittle, it would generate cracks by impact load during transportation, signifying leakage of radioactive ray. In order to design the safety transporting equipment, there is a need to check the compressive strength of the current waste. However, because it is impossible to measure strength by direct method due to leakage of radioactive ray, we will estimate the strength indirectly by the dynamic modulus of elasticity. Therefore, it must be identified the relationship between of strength and dynamic modulus of elasticity. According to the waste acceptance criteria, the compressive strength of cement based solid is defined as more than 3.44 MPa (500 psi). Compressive strength of the present solid is likely to be significantly higher than this baseline because of continuous hydration of cement during long period. On this background, we have tried to produce the specimens of the 28 day's compressive strength of 3 to 30 MPa having the same material composition as the solid product for the medium-low level radioactive waste, and analyze the relationship between the strength and the dynamic modulus of elasticity. By controling the addition rates of AE agent, we made the mixture containing the ion exchange resin and showing the target compressive strength (3~30 MPa). The dynamic modulus of elasticity of this mixtures is 4.1~10.2 GPa, about 20 GPa lower in the equivalent compressive strength level than that of ordinary concrete, and increasing the discrepancy according to increase strength. The compressive strength and the dynamic modulus of elasticity show the liner relationship.

• Tuberculosis and Respiratory Diseases
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• v.48 no.3
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• pp.347-356
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• 2000

Background : Patients with obstructive sleep apnea syndrome are known to have high long-term mortality compared to healthy subjects because of their cardiovascular dysfunction. The observation of hemodynamic changes by obstructive apneas is helpful when attempting to understand the pathophysiological mechanism of the development of cardiovascular dysfunction in those patients. Therefore, we studied the changes in cardiovascular function with an animal model and tried to obtain the basic data for an ideal experimental model (this phrase is unclear), a requirement for a more advanced study. Methods : Sixteen anesthetized dogs with ${\alpha}$-chloralose delete were divided into two groups : 8 dogs of room air breathing group and 8 dogs of oxygen breathing group. We measured $PaO_2$, $PaCO_2$, heart rate, cardiac output, mean femoral artery pressure, and mean pulmonary artery pressure at specified times during the apnea-breathing cycle before endotracheal tube occlusion (baseline), 25 seconds after endotracheal tube occlusion (apneic period), 10 seconds (early phase of postapneic period, EPA) and 25 seconds (late phase of postapneic period, LPA) after spontaneous breathing. Results : In room air breathing group, the heart rate significantly decreased during the apneic period compared to that at baseline (P<0.01) and increased at EPA and LPA compared to that during the apneic period (P<0.01). But, the heart rate showed no significant changes during apneic and postapneic periods in the oxygen breathing group. Cardiac output tended to decrease during apneic period compared to that at baseline, but was statistically significant. Cardiac output significantly decreased at LP A compared to at baseline (P<0.01). Mean femoral artery pressure was significantly decreased at during apneic period compared to that at baseline (P<0.05). Conclusion : Through this experiment, we were partially able to understand the changes of cardiovascular function indirectly, but delete new experimental animal model displaying physiological mechanism close to natural sleep should be established, and the advanced study in the changes of cardiovascular function and their causes should be continued.

• Tuberculosis and Respiratory Diseases
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• v.47 no.6
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• pp.768-774
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• 1999

Background: It is well known that rifampin decreases the hypoprothrombinemic effect of warfarin by induction of cytochrome P-450 enzyme in healthy volunteer. However, in patients the dosage schedule of warfarin during rifampin therapy is not established. Therefore, patients taking both rifampin and warfarin were reviewed to find out the adequate dosage schedule of warfarin in addition to side effects by interaction of two drugs. Method: Patients taking both rifampin and warfarin were retrieved from patients who were admitted due to heart disease and tuberculosis at Boochun Sejong Hospital from January of 1995 to August of 1999. To decide the adequate dosage of warfarin, the dosage of warfarin before, during, and after rifampin was evaluated in patients who kept adequate hypoprothrombinemic effect of warfarin during rifampin. To decide the adequate dosage schedule of warfarin, the time interval from the beginning of rifampin to normalization of prothrombin time(INR$\geq$1.1) was evaluated. And, the side effects by interaction of two drugs were reviewed. Results: All 12 patients taking both rifampin and warfarin were retrieved. Among them only 6 kept adequate hypoprothrombinemic effect of warfarin during rifampin. The dosage of warfarin during rifampin was $2.4{\pm}0.6$(mean$\pm$standard deviation) times as much as that before rifampin but the dosage after rifampin was the same as that before rifampin. The time interval from the beginning of rifampin to normalization of prothrombin time was $5.8{\pm}2.9$(mean${\pm}$standard deviation) days. 2 out of 12 had complication related to the interaction of rifampin and warfarin, one cerebral embolism just after the beginning of rifampin and the other cerebral hemorrhage just after the discontinuation of rifampin. Conclusion: When both rifampin and warfarin are prescribed, it would be a possible method to be confirmed by prospective study that warfarin be gradually increased about 2 times more than that without rifampin over 1 week or so after the beginning of rifampin and be tapered to the same dosage as that before rifampin when rifampin is discontinued. And, it would be prudent that prothrombin time be monitored frequently during rifampin and warfarin therapy, especially the beginning or discontinuation of rifampin.