• Restorative Dentistry and Endodontics
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• v.14 no.2
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• pp.38-48
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• 1989

The purpose of this study was to investigate the proper consistency of root canal sealer needed in obtaining an efficient canal obturation in injection-thermoplasticized low-temperature ($70^{\circ}C$) gutta-percha method. The sealer was made by incorporating zinc oxide powder into $0.5m{\ell}$ of eugenol and then the $0.5m{\ell}$ of mixture slurry was placed between two flat glass plates. The consistency was determined by measuring the degree of spread of the slurry at loading the 120gm of weight from the top plate. The sealer was prepared according to P/L ratio corresponding to the acquired consistency of 65.45mm, 46.80mm, 28.95mm and 22.60mm. The distal roots were obtained by cutting off from 125 extracted human lower molars and the root canals were prepared by using step-back method. The prepared canals were coated with the sealers on their walls and obturated by using the injection-thermoplasticized low-temperature ($70^{\circ}C$) gutta-percha method. All specimens were immersed in 2% methylene blue dye solution for 48 hours at $37^{\circ}C$. Calipers was used to measured the dye penetration into the root canals from apical constrictions. The results were as follows : The canals obturated without sealer showed significantly more leakage than the canals obturated with sealer. Within the consistency from 65.45mm to 22.60mm, the sealer of 65.45mm appeared significantly better than that of 28.95mm and 22.60mm in the canals obturated by injection-thermoplasticized gutta-percha method, and better than that of 46.80mm without statistical significance.

• Clean Technology
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• v.8 no.3
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• pp.151-165
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• 2002

In the treatment of the wastewater containing metals($Cu^{2+}$, $Zn^{2+}$, $Ni^{2+}$, $Cr^{3+}$) by using batch precipitation and flocculation followed by membrane filtration, permeate flux and removal efficiency were investigated according to by the effect of pH and coagulants, and the type of membranes used and pore size. It was found that it is most effective to use $0.45{\mu}m$-polysulfone membrane and coagulant(PAC) at the conditions of the pH of 10.0~10.5 for the case of copper containing wastewater, $0.1{\mu}m$-PVDF membrane and coagulant(PAC) at the conditions of the pH of 10.0~10.5 for the case of zinc containing wastewater, $0.1{\mu}m$-PVDF membrane and coagulant at the conditions of the pH of 11.0~11.5 for the case of nickel containing wastewater, $0.2{\mu}m$ membrane and coagulant at the conditions of the pH of 8.0~8.5 for the case of chromic containing wastewater, and $0.2{\mu}m{\sim}0.45{\mu}m$ membrane and coagulant at the conditions of the pH of 11.0~11.5 for the case mixture wastewater. The permeate flux could higher as to be used coagulants except for the case of copper containing wastewater.

• Journal of Korean Society of Forest Science
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• v.86 no.4
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• pp.435-442
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• 1997

The research was carried out to investigate the contamination of stream water by the acid mine drainage originated from the abandoned coal mines and coal waste rock in Keumsan, Chungnam. The pH, sulfate and chemical compositions in the stream water were analyzed. At the polluted sites, the pH of stream water was the strong acid, ranging from 3.46 to 4.29. The pH shows negative correlations with sulfate, manganese, copper, zinc, iron and magnesium concentrations. Sulfate concentrations of the polluted stream water, 236.73-310.53mg/l, had 10 times more than those of the non-polluted stream water. The concentrations of heavy metals, Mn and Fe, in the polluted water were 0.56 - 0.83mg/l and 5.89 - 10.58mg/l, respectively. The Mn concentrations were 20 times higher than those of the non-polluted stream water. Compared with those in the non-polluted stream water, the Mg and Ca concentrations in the polluted stream water were high because of leaching from rock and soil to water by the acidifications. Calculated AMDI(Acid Mine Drainage Index) values are low in the polluted stream water, relative to those of the non-polluted water.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.3
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• pp.260-272
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• 2001

All-ceramic restorations have had a more limited life expectancy than metal ceramic restorations because of their low strength. Their relatively lower strength and resistance to fracture have restricted the use of all-ceramic crowns to anterior applications where occlusal loads are lower. But there has been increasing interest in all-ceramic restorations because patients are primarily concerned with improved esthetics. Many efforts have been made to in prove the mechanical properties of dental ceramics. This study was designed to elucidate the influence of the luting agent on the strength of the Empress 2 crown (staining technique) cemented on human teeth. Seventy extracted human permanent molar teeth were chosen. Teeth were prepared for Empress 2 crowns with milling machine on a surveyor. A dental bur was placed in the mandrel that was positioned so that the long axis of the bur was perpendicular to the surveyor base. Dimensions of the Empress 2 crown preparation were $6^{\circ}$ taper on each side, $1.5{\pm}0.1mm$ shoulder margin, and 4mm crown height. The luting cements used in this study were as follow: 1. Uncemented 2. Zinc phosphate cements (Confi-Dental) 3. Conventional glass ionomer cement : Fuji 1 (GC) 4. Resin-modified glass ionomer cements : Fuji plus (GC) 5. Adhesive cements : Panavia F (Kuralay), Variolink II (Vivadent), Choice (Bisco). Fracture test using Instron. The crowns were loaded in compressive force to evaluate the effect of these cements on the breaking strength of these all-ceramic crowns. A steel ball with a diameter of 4mm was placed on the occlusal surface and load was applied to the steel ball by a cylindrical bolt with a crosshead speed of 0.5mm per minute until fracture occurred. The fractured surface was examined using Scanning Electron Microscopic Image (SEM) to discover the correlation between fracture strength and bonding capacity. Within the limitation of this in vitro study design, the results were as follows : 1. fomentations significantly increased the fracture resistance of Empress ceramic crowns compared to control. Uncemented (206.9 N): ZPC (812.9 N): Fuji 1 (879.5 N): Fuji Plus (937.7 N): Choice (1105.4 N): Variolink II (1221.1 N): Panavia F (1445.2 N). 2. Resin luting agent, treated by a silane bond enhancing agents, yielded a significant increase in fracture resistance. In some of the Panavia F group, a fracture extended into dentin. 3. According to SEM images of fractured Empress crowns, the stronger the bond at both interfaces(crown and die), the more fracture strength was acquired.

• The Journal of Advanced Prosthodontics
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• v.1 no.2
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• pp.85-90
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• 2009

STATEMENT OF PROBLEM. Over the years, resin-bonded fixed partial dentures (RBFPDs) have gone through substantial development and refinement. Several studies examined the biomechanics of tooth preparation and framework design in relation to the success rate of RBFPDs and considered retention and resistance form essential for increase of clinical retention. However, these criteria required preparations to be more invasive, which violates not only the original intentions of the RBFPD, but may also have an adverse effect on retention due to loss of enamel, an important factor in bonding. PURPOSE. The object of this in vitro study was to compare the dislodgement resistance of the new types of RBFPDs, the conventional three-unit fixed partial denture, and conventional design of RBFPD (Maryland bridge). MATERIAL AND METHODS. Fifty resin mandibular left second premolars and second molars were prepared on dentiforms, according to the RBFPD design. After model fabrication (five group, n = 10), prostheses were fabricated and cemented with zinc phosphate cement. After cementation, the specimens were subjected to tensile loading at a cross head speed of 4 mm/min in a universal testing machine. The separation load was recorded and analyzed statistically using one-way analysis of variance followed by Duncan's multiple range test. RESULTS. Group V, the pin-retained RBFPDs, had the highest mean dislodgement resistance, whereas specimens of group II, the conventional RBFPDs, exhibited a significantly lower mean dislodgement resistance compared to the other 4 groups (P <.05). There were no significant differences between group I, III, and IV in terms of dislodgement resistance (P>.05). Group V had the highest mean MPa (N/$mm^2$) (P <.05). There was no significant difference between groups I, II, III and IV (P > .05). CONCLUSION. Within the limits of the design of this in vitro study, it was concluded that: 1. The modified RBFPDs which utilizes the original tooth undercuts and requires no tooth preparation, compared with the conventional design of RBFPDs, has significantly high dislodgement resistance (P < .05). 2. The modified RBFPDs which utilizes the original tooth undercuts and requires minimal tooth preparation, compared with the conventional FPDs, has significantly no difference in retention and dislodgement resistance)(P>.05). 3. The pin-retained FPDs showed a high dislodgement resistance compared to the conventional three-unit FPDs (P<.05).

• Journal of Hydrogen and New Energy
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• v.26 no.5
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• pp.423-430
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• 2015

$Cu/ZnO/Al_2O_3$ catalysts for water gas shift (WGS) reaction were synthesized by co-precipitation method with the fixed molar ratio of Cu/Zn/Al precursors as 45/45/10. Copper and zinc precursor were added into sodium carbonate solution for precipitation and aged for 24h. During the aging period, aluminum precursor was added into the aging solution with different time gap from the precipitation starting point: 6h, 12h, and 18h. The resulting catalysts were characterized with SEM, XRD, BET surface measurement, $N_2O$ chemisorption, TPR, and $NH_3$-TPD analysis. The catalytic activity tests were carried out at a GHSV of $27,986h^{-1}$ and a temperature range of 200 to $400^{\circ}C$. The catalyst morphology and crystalline structures were not affected by aluminum precursor addition time. The Cu dispersion degree, surface area, and pore diameter depended on the aging time of Cu-Zn precipitate without the presence of $Al_2O_3$ precursor. Also, the interaction between the active substance and $Al_2O_3$ became more stronger as aging duration, with Al precursor presented in the solution, increased. Therefore, it was confirmed that aluminum precursor addition time affected the catalytic characteristics and their catalytic activities.

• Korean Journal of Environmental Agriculture
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• v.9 no.2
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• pp.121-131
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• 1990

Four crop plants, such as green onion(Allium ascalonicum L.), radish(Raphanus sativus L.), potato(Solanum tubersum L.) and chinese cabbage(Brassica pekinensis Rupr), were grown in greenhouses to determine the accumulations of Cd and Zn absorbed by the plants grown on soils treated with municipal sewage sludge of different levels of 0, 22.5, 45.0 and 90.0 ton $ha^{-1}$ as soil dry weight. The result was analyzed to be comparable to the heavy metal content in the plant tissues among the crop species and the statistical characteristics were investigated to determin a possible relationship between causes of increased contents of Cd and Zn in plants and in soils. The results were as follows : 1. The Cd and Zn content in experimental crop plants increased with increase in quantity of treatment sludge. 2. The Cd and Zn content in roots of all experimental plants increased with sludge treatment amount in soil, in the following order : green onion>potato>chinese cabbage>radish. 3. The Cd content in leaves of crop plants were high in this order : green onion>radish>potato>chinese cabbage, and the Zn content in leaves of crop plants was high in this order. : potato>radish>chinese cabbage>green onion. 4. Concentrations of Cd in potato tubers, radish roots and chinese cabbage leaves ranged from 0.03 to 0.12 ppm. 5. Concentrations of Cd and Zn in plant tissues grown in sludge treated soil of 90.0 ton $ha^{-1}$ were 1.2 to 10 times and 0.4 to 2.3 times higher as compared with those absorbed from sludge-free soil, respectively. 6. The accumulation rates of Cd and Zn in sludge-treated plant tissue were almost constant except for green onion roots.

• Journal of Nutrition and Health
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• v.38 no.7
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• pp.570-577
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• 2005

The purpose of this study was to investigate the effect of bone mineral density on life styles, dietary habits and nutrient intakes among the male college students. The subjects were divided into four groups; $Q_1$ (calcaneus BMD < 25 percentile, n = 117), $Q_2$ (25 percentile $\le$ calcaneus BMD < 50 percentile, n = 118), $Q_3$ (50 percentile $\le$ calcaneus BMD < 75 percentile, n = 118) $Q_4$ (calcaneus BMD $\ge$ 75 percentile, n = 116). And they were asked about general characteristics, life style, dietary habit, and nutrient intake using questionnaire and 24-hr recall method. They were measured the bone mineral density of calcaneus using quantitative ultrasound. The average age of the subjects of the study was 23.0 yews and the average height, weight, and BMI were 174.7 cm, 69.0 kg, $22.5 kg/m^2$. The bone mineral density in calcaneus was $0.43 g/cm^2$ in $Q_1,\;0.50 g/cm^2$ in $Q_2,\;0.56 g/cm^2$ in $Q_3$, and $0.69 g/cm^2$ in $Q_4$ (p < 0.001). The results showed that $Q_1$ tended to have irregular exercise compared to the other three groups. Compared with $Q_1$ and $Q_2$, the frequency of skipping breakfast was lower in $Q_3$ and $Q_4$. Also the results showed that the $Q_4$ was significantly more often to drink coffee compared with the other three groups (p < 0.01). The mean daily energy intake was 2210.6 kcal ($88.4\%$ of RDA). The intake of energy, vitamin $B_2$, calcium, and zinc did not meet the Korean RDA. Also the $Q_2$consumed significantly lower intakes of protein (p < 0.05) and plant protein (p < 0.05) compared to the $Q_3$ and $Q_4$. The $Q_1$ and $Q_2$ consumed significantly lower intakes of vitamin $B_2$ (p < 0.01) compared to the $Q_3$ and $Q_4$. In conclusion, male student in lower bone mineral density appeared to have unhealthy life styles and dietary habits in terms of irregular exercise, high frequency of skipping breakfast and lower intakes of protein, vitamin $B_2$ showing a strong need proper education on meal practices and exercise habits for the bone health.

• Journal of Biomedical and Translational Research
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• v.19 no.4
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• pp.116-124
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• 2018

Korean Native Pig (KNP) has a uniform black coat color, excellent meat quality, white colored fat, solid fat structure and good marbling. However, its growth performance is low, while the western origin Yorkshire pig has high growth performance. To take advantage of the unique performance of the two pig breeds, we raised crossbreeds (KNP ${\times}$ Yorkshire to make use of the heterotic effect. We then analyzed the liver transcriptome as it plays an important role in fat metabolism. We sampled at two stages: 10 weeks and at 26 weeks. The stages were chosen to correspond to the change in feeding system. A total of 16 pigs (8 from each stage) were sampled and RNA sequencing was performed. The reads were mapped to the reference genome and differential expression analysis was performed with edgeR package. A total of 324 genes were found to be significantly differentially expressed (${\left|log2FC\right|}$ > 1 & q < 0.01), out of which 180 genes were up-regulated and 144 genes were down-regulated. Principal Component Analysis (PCA) showed that the samples clustered according to stages. Functional annotation of significant DEGs (differentially expressed genes) showed that GO terms such as DNA replication, cell division, protein phosphorylation, regulation of signal transduction by p53 class mediator, ribosome, focal adhesion, DNA helicase activity, protein kinase activity etc. were enriched. KEGG pathway analysis showed that the DEGs functioned in cell cycle, Ras signaling pathway, p53 signaling pathway, MAPK signaling pathway etc. Twenty-nine transcripts were also part of the DEGs, these were predominantly Cys2His2-like fold group (C2H2) family of zinc fingers. A protein-protein interaction (PPI) network analysis showed that there were three highly interconnected clusters, suggesting an enrichment of genes with similar biological function. This study presents the first report of liver tissue specific gene regulation in a cross-bred Korean pig.

• Journal of Life Science
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• v.31 no.7
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• pp.641-653
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• 2021

The purpose of this study was to confirm the antifungal activity, plant growth-promoting activity, and mineral solubilizing activity of 18 types of bacteria isolated purely from rhizosphere soil. The potential of isolates of the genus Bacillus and Pseudomonas as biocontrol agents was confirmed through the antifungal activity of these isolates. This activity has been determined to be due to various hydrolytic enzymes on the cell wall of plant pathogenic fungi and the production of siderophores in isolates. In addition, most of the isolates have been found to have aminocyclopropane-1-carboxylate deaminase production activity, indole-3-acetic acid production activity, and nitrogen fixation activity. These characteristics are believed to have a positive effect on root development, growth, and the productivity of crops via a reduction in the concentration of ethylene under conditions of environmental stress, to which plants are commonly exposed. In addition, on testing for the solubilizing activity of the isolates for phosphoric acid, silicon, calcium carbonate, and zinc, some isolates were found to have mineral solubilizing activities. Inoculation of these isolates during plant growth is expected to assist plant growth by converting nutrients necessary for growth into usable forms that can be absorbed by plants. The 18 isolated strains can be used as biocontrol agents due to their antifungal activity, plant growthpromoting activity, and mineral solubilizing activity.