• Journal of dental hygiene science
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• v.15 no.3
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• pp.318-324
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• 2015

The purpose of this study is to provide the basic date which is increase the number of revisits for scaling after analyzing factors that influence trend of dental revisits for 7 years. Research data was about 1,471 patients who visited S dental clinic in Seoul at 2007 for scaling. Data from January 2007 to December 2013 was collected. The subjects were divided into 3 groups by their trend in number of dental revisits for scaling: once, 2 times, 3~7 times. The data were analyzed using the chi-squire, independent-samples t-test and one-way ANOVA, binary logistic regression analysis. As a result, the trend of dental revisit for scaling is significantly decreased from first time to second time, and after 3rd time dental revisits were steadily continued. Factors affecting dental revisits for scaling are distance, family hospital, systemic disease, presence or absence of periodontal therapy. According to the results of the study, providing dental service in accordance with the patients' characteristics and increasing the dental revisits for scaling could give a positive influence to improvement of oral health.

• Membrane Journal
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• v.17 no.2
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• pp.124-133
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• 2007

In this study, we treated lake water by 2 kinds of multichannel ceramic micro filtration membranes. We could investigate effects of $N_2-back-flushing$ time (BT) and transmembrane pressure (TMP), and find optimal operating conditions. The BT were changed in $10{\sim}60$ sec, TMP in $0.6{\sim}2.0$ bar at fixed filtration time (FT) 8 min, flow rate 2.0 L/min and back-flushing pressure 2.0 bar. Also, the optimal conditions were discussed in the viewpoints of resistance of membrane fouling $(R_f)$, dimensionless permeate flux $(J/J_o)$, permeate flux (J) and total permeate volume $(V_T)$. As result, optimal back-flushing conditions for HC04 ($0.4{\mu}m$ pore size) and HC10 membrane $(1.0{\mu}m)$ were BT=10 sec and BT=20 sec, respectively. Then, higher TMP should increase the driving force, and could produce more VT. Average rejection rates of pollutants were higher than 95.4% for turbidity, $12.7{\sim}20.1%\;for\;COD_{Mn},\;0.0{\sim}6.4%\;for\;NH_3-N,\;1.9{\sim}4.6%$ for T-N and $34.9{\sim}88.4%$ for T-P.

• Journal of Korean Society on Water Environment
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• v.33 no.1
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• pp.90-96
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• 2017

Many sewage treatment plants have applied the advanced technology of chemical coagulant system to remove phosporus in Korea. However there are some problems for the injection of optimum coagulant dosage. In order to solve these problems, the research related to the more cost-effective automatic total phosphorus coagulation control system using an EC(Electrical Conductivity) have been in progress. This study was conducted by the same process and operation method as the Lab-scale for public small town sewage treatment plant. First, it confirmed the correlation among the EC, PO4-P and coagulant dosage in the Lab-scale MSBR(Membrane Sequencing Batch Reactor) process. Next, it analyzed that correlation coefficient of EC and the coagulant dosage was 0.92 in the Full-scale MSBR process. As a result, not only T-P removal efficiency was doubled but also it satisfied the effluent water quality standard in a stable manner. In addition, by applying the automatic control system using the EC, compared to the fixed coagulant injection system the coagulant dosage could be reduced by 28%.

• Journal of Embryo Transfer
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• v.33 no.3
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• pp.129-137
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• 2018

Acute vascular rejection has been known as a main barrier occurring in a xenograted tissue of alpha 1,3-galactosyltransferase knock-out (GalT KO) pig into a non-human primate (NHP). Adenosine which is a final metabolite following sequential hydrolysis of nucleotide by ecto-nucleotidases such as CD39 and CD73, act as a regulator of coagulation, and inflammation. Thus xenotransplantation of CD39 and CD73 expressing pig under the GalT KO background could lead to enhanced survival of recipient NHP. We constructed a human CD39 and CD73 expression cassette designed for endothelial cell-specific expression using porcine Icam2 promoter (pIcam2-hCD39/hCD73). We performed isolation of endothelial cells (pAEC) from aorta of 4 week-old GalT KO and membrane cofactor protein expressing pig ($GalT^{-MCP/-MCP}$). We were able to verify that isolated cells were endothelial-like cells using immunofluorescence staining analysis with von Willebrand factor antibody, which is well known as an endothelial maker, and tubal formation assay. To find optimal condition for efficient transfection into pAEC, we performed transfection with GFP expression vector using four programs of nucleofection, M-003, U-023, W-023 and Y-022. We were able find that the program W-023 was optimal for pAEC with regard to viability and transfection efficiency by flow cytometry and fluorescent microscopy analyses. Finally, we were able to obtain $GalT^{-MCP/-MCP}/CD39/CD73$ pAEC expressing CD39 and CD73 at levels of 33.3% and 26.8%, respectively. We suggested that pACE isolated from $GalT^{-MCP/-MCP}$ pig might be provided as a basic resource to understand biochemical and molecular mechanisms of the rejections and as an alternative donor cells to generate $GalT^{-MCP/-MCP}/CD39/CD73$ pig expressing CD39 and CD73 at endothelial cells.

• Journal of dental hygiene science
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• v.13 no.4
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• pp.434-439
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• 2013

This study was conducted to compare the dental plaque reduction using various mouthwashes with Quantitative Light induced Fluorescence-Digital (QLF-D). A survey on 20 students was carried out. The students who were at Shingu College. Experimental group was gargled 20 ml of Listerine during 30 seconds and 15 ml of Hexamedine during 60 seconds. Control group was gargled distilled water during 30 second. The data were analyzed with t-test using SPSS 20.0 program. The ratios of control group and experimental group were reduced. Degree of ${\Delta}R30$ and ${\Delta}R70$ Listerine group was a significant difference (p>0.05). Degree of Simple Plaque Score and ${\Delta}R30$ Hexamedine group was a significant difference (p>0.05). There was no significant difference in the distilled water gargle group (p<0.05). The result of this study has the effect of two mouthwashes reduced dental plaque. The evaluation data of this study will be used in clinical application and research about QLF-D.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.1
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• pp.53-61
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• 2013

The characteristics of methane production from pig manure slurry was investigated using anaerobic digestor combined with compost filtration bed. In this study, raw pig manure slurry was digested in mesophilic rectangular digester (effective volume $250m^3$) for 25 days and anaerobic digestion wastewater was filtered through compost filtration bed, which is composed of double layer, sawdust and chaff. The characteristics of anaerobic digestion wastewater were BOD 1,800 mg/L, COD 3,500 mg/L, SS 11,800 mg/L, T-N 1,200 mg/L and T-P 350 mg/L. After the filtration process, the contents of BOD, COD, SS, T-N and T-P of the anaerobic digestion wastewater were reduced by 97%, 62%, 89%, 39% and 57%, respectively. The concentrations of N, $P_2O_5$, and $K_2O$ of the leachate were 1,024, 111 and 407 mg/L, respectively. However, there was no odor emitted from the leachate.

• Korean Journal of Animal Reproduction
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• v.23 no.2
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• pp.149-157
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• 1999

The functional role of cumulus cells on the penetration and polyspermy during in vitro fertilization in porcine was examined. The penetration rate was significantly higher (P＜0.01) in oocytes with (61%) than without (25%) cumulus cells, but significant differences in polysper-my rates were not observed. When hyaluronidase was added to the fertilization medium with different concentrations, penetration rates in oocytes with cumulus cells were higher than in oocytes without cumulus cells at 0 (61% vs 34% ; P＜0.05), 0.01 (56% vs 35% ; P＜0.05), 0.1 (66% vs 30% ; P＜0.05) and 1.0mg/$m\ell$ (39% vs 27%). The polyspermy rates were lower in oocytes without than with cumulus cells, and had a tendency to decrease with high concentrations of hyaluronidase. In another experiment, the penetration and polyspermy rates had a tendency to increase as time of sperm-oocyte culture was prolonged. At 16 and 20 h after insemination, the penetration rates were significantly higher (P＜0.05) in oocytes with (48 and 62% for 16 and 20 h) than without (25 and 31% for 16 and 20 h) cumulus cells in medium containing hyaluronidase. Polyspermy rates were significantly (P＜0.05) lower in oocytes without (13% and 16%) than with (37% and 48%) cumulus cells at 16 and 20 h after insemination. In cumulus-free oocytes inseminated in medium containing different concentrations of cumulus cells, the penetration rates were significantly (P＜0.05) higher in medium with than without hyaluronidase. The proportion of polyspermy was lower in medium without than with hyaluronidase at 0 (10% vs 0%), 10$^2$(25% vs 0%), 10$^4$(24% vs 14%) and 10$^{6}$ (29% vs 10% ; P＜0.05) cumulus cells/$m\ell$. These results suggest that cumulus cells can have a positive influence on sperm penetration, its action on polyspermy control does appear to function primarily on zona pellucida by co-culture of cumulus cells and oocytes in medium without hyaluronidase.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1893-1904
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• 2000

Nitrogen compounds are one of the major pollutants which cause eutrophication problems of the river or lake and red tides problems of the ocean. Currently available technologies for the removal of nitrogen compounds are mostly biological treatment. However, biological treatment is only effective for the wastewater which contains low concentration of nitrogen compounds. Leachate from solid waste landfill or industrial wastewater which contains high concentration of nitrogen can not be effectively treated by most of the currently available biological treatment technologies. With this connection. the objective of this study is to examine the applicability of ammonia stripping technology for the removal of high concentration of ammonia nitrogen compounds of the leachate from solid waste landfill. It can be concluded that ammonia stripping technology which was placed before the biological treatment process was very effective for the removal of high concentration of ammonium compounds. The chemical cost for the ammonia stripping was 16 percent higher than MLE process, so other methods like sludge recycling are needed for the reduction of operation cost. Further details are discussed in this paper.

• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.1013-1023
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• 2003

This study was performed to improve water quality of stream by applying hydraulic structures (weir and river bed material) made of porous concrete. The physical and chemical characteristics of porous concrete were measured to estimate application possibility of it in hydraulic structures and it was considered as a proper material for the hydraulic structures. In the results of comparison for the component of matters attached on the hydraulic structures made of porous and ordinary concrete, DW (dry weight) amount attached on porous concrete was 1.6 times higher than that on ordinary concrete under the condition of the same flow rate but influence by flow rate (difference of 10 times) was not shown. Therefore, we could understand that the material of media was more important in DW amount than flow rate. The rate of AFDM (ash free dry mass) to DW also was more at porous concrete than at ordinary concrete. Especially, the high rates of nitrogen and phosphorous in matters attached on porous concrete verify that they were removed by assimilation, adsorption and metabolism of periphyton. The removal percentage of SS, BOD, COD, T-N and T-P by hydraulic structures applying porous concrete compared with ordinary concrete was increased by 34.6%, 36.9%, 33.9%, 18.3% and 21.6%, respectively. Therefore, applying porous concrete to hydraulic structure is expected to contribute to improvement of stream water quality.

• KSBB Journal
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• v.18 no.4
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• pp.318-323
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• 2003

This study was carried out to investigate the possibility of reusing newspaper or paperbox waste by methane fermentation. When 15 g of newspaper and box wastes were digested separately for 24 days by batch fermentation, the amount of total organic acids produced were 2461 and 4978 mg/L, respectively. The tCOD removal rates were found to be 60.9 and 62.4%, respectively. In addition, the removal efficiencies of total solid were 34.8 and 33.4%, and those of volatile solid were 40.0 and 39.2%, respectively. During this period, the amounts of biogas produced were 6.95 and 6.43 L. In a semicontinuous reaction, tCOD removal efficiencies for newspaper and box wastes were 64.7 and 65.0%, respectively, after 14 days of digestion. After 25 days, which were needed to stabilize the methane fermentation, the amounts of biogas produced daily were 0.31 and 0.30 L/g.dry wt, respectively. Methane contents were 57.3 and 56.2%, respectively, and the pHs in the anaerobic acidogenic and methanogenic fermenters were 5.0 and 7.5, respectively.