• Proceedings of the KSME Conference
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• 2000.04b
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• pp.441-446
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• 2000

Chemical compositions of monodisperse $SiO_2/TiO_2$ multicomponent aggregates were measured for different heights from the burner surface and different mobility diameters of aggregates. $SiO_2/TiO_2$ multicomponent particles were generated in a hydrogen/oxygen coflow diffusion flame from two sets of precursors: TTIP (titanium tetraisopropoxide), TEOS(tetraethylorthosilicate). To maintain 1:1 mole ratio of TTIP:TEOS vapor theoretically, flow rate of carrier gas $N_2$ was fixed at 0.61pm for TTIP, at 0.11pm for TEOS. In situ sampling probe was used to supply particles into differential mobility analyzer(DMA) which was calibrated with using commercial DMA(TSI 3071A) and classifying monodisperse multicomponent particles. Classified particles were collected with electrophoretic collector. The distributions of composition from particle to particle were determined using EDS (energy dispersive spectrometry) coupled with TEM (transmission electron microscope). The chemical (atomic) compositions of classified monodisperse particle were obtained for different heights; z=40mm, 60mm, 80mm. The results suggested that the atomic composition of $SiO_2$ decreased with the height from burner surface and the composition of $SiO_2$ and $TiO_2$ approached to the value of 1 to 1 in far downstream. It is also found that the composition of $SiO_2$ decreases as the mobility diameter of aggregate increases.

• Journal of Korean Society on Water Environment
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• v.30 no.4
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• pp.394-402
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• 2014

High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH, $H_2O_2$ and $O_3$. The experimental results showed that the optimum 1st voltage and oxygen flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the 2nd voltage (4 kV to 15 kV) was increase, RNO degradation was increased and, generated $H_2O_2$ and $O_3$ concentration were increased. The conductivity of the solution was not influencing the RNO degradation, $H_2O_2$ and $O_3$ generation. The pH effect on RNO degradation was not high. However, the lower pH and the conductivity, the higher $H_2O_2$ and $O_3$ generation were observed.

• Journal of Chest Surgery
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• v.29 no.2
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• pp.199-207
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• 1996

Ischemic myocardial damage is inevitable to cardiac surgery. Myocardial damage after initiation of reperfusion through the coronary arteries is one of the most important determinants of a successful surgery. Adenosine is a potent vasodilator, and is also known to induce rapid cardioplegic arrest by its property of antagonizing cardiac calcium channels and activating the potassium channel. Thus, we initiated this study with adenosine to improve postischemic recovery in the isolated rat heart. We tested the hypothesis that adenosine could be more effective than potassium in inducing rapid cardiac arrest and enhancing postischemlc hemodynamic recovery. Isolated rat hearts, connected to the Langendorff appratus, were perfused with Krebs-Henseleit buffer and all hearts were subjected to arrest for 60 minutes. Three groups of hearts were studied according to the composition of cardioplegic solutions : Group A (n=10), adenosine 10mmo1/L+potassium free modified St. Thomas cardioplegia : Group B (n=10), adenosine 400mo1/L+S1. Thomas cardioplegia:Group C(control, n=10), St. Thomas cardioplegia. Adenosine-treated groups (group A & B) resulted in more rapid cardiac arrest than control group (C) (p< 0.01). There was greater improvement in recovery of coronary blood flow at 20 and 30 minutes of reperfusion in group A and at 20 minutes in group B when compared with control group(p<0.01). Recovery of systolic blood pressure at 10 minutes after reperfusion in group A and B was significantly superior to that in group C (p<0.01). Recovery of dp/dt at 10 minute after reperfusion in group A was also significantly superior to group C (p<0.05). Group A and B showed better recovery rates than control group in aortic blood flow, cardiac output, and heart rate, but there were no statistical differences. CPK levels of coronary flow in group A were significantly low (p< 0.01). We concluded that adenosine-enriched cardioplegic solutions have better effects on rapid cardiac arrest and postischemic recovery when compared with potassium cardioplegia.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.697-708
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• 1992

Liquid Chromatographic behavior of Ni(II) in Isonitrosoethylacetoacetate Imine(IEAA-NR), Ni(IEAA-NH)(IEAA-NR)(R = H, CH_3, C-2H_5, n-C_4H_9, C_6H_5-CH_2) chelates were investigated by reversed-phase HPLC on Micropak MCH-5 column using methanol/water as mobile phase. The optimum conditions for the separation of Ni(IEAA-NH)(IEAA-NR) chelates were examined with respect to the effect of the flow rate, sample solvent, mobile phase strength and column temperature. It was fo$und that metal chelates were properly eluted in an acceptable range of capacity factor value(0{\le}logk'{\le}1). The dependence of the logarithm of capacity factor (k') on the volume fraction of water in the binary mobile phase as well as on the liquid-liquid extraction distribution ratio (Dc) in methanol-water/n-alkane extraction system showed the good linearties, and the dependence of the logarithm of capacity factor (k') on the column temperature and on the enthalpy exhibited the good linearties, and the compensation temperature ({\beta}) from the slope was 773.47{\circ}K. It was suggested that the retention of metal chelates was largely affected by the hydrophobic effect.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1561-1569
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• 2013

This study carried out a laboratory scale plasma reactor about the characteristics of chemically oxidative species (${\cdot}OH$, $H_2O_2$ and $O_3$) produced in dielectric barrier discharge plasma. It was studied the influence of various parameters such as gas type, $1^{st}$ voltage, oxygen flow rate, electric conductivity and pH of solution for the generation of the oxidant. $H_2O_2$ and $O_3$.) $H_2O_2$ and $O_3$ was measured by direct assay using absorption spectrophotometry. OH radical was measured indirectly by measuring the degradation of the RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical). The experimental results showed that the effect of influent gases on RNO degradation was ranked in the following order: oxygen > air >> argon. The optimum $1^{st}$ voltage for RNO degradation were 90 V. As the increased of $1^{st}$ voltage, generated $H_2O_2$ and $O_3$ concentration were increased. The intensity of the UV light emitted from oxygen-plasma discharge was lower than that of the sun light. The generated hydrogen peroxide concentration and ozone concentration was not high. Therefore it is suggested that the main mechanism of oxidation of the oxygen-plasma process is OH radical. The conductivity of the solution did not affected the generation of oxidative species. The higher pH, the lower $H_2O_2$ and $O_3$ generation were observed. However, RNO degradation was not varied with the change of the solution pH.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.1
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• pp.79-91
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• 2005

Wetland systems are widely accepted natural water purification systems around the world in nonpoint sources pollution control. Constructed wetlands have become a popular technology for treating contaminated surface and wastewater. In this study, the field experiment to reduce nonpoint source pollution loadings from polluted stream waters using wetland system was performed from June 2002 to March 2004, including winter performance using four newly constructed wetlands. The Dangjin stream water flowing into Seokmun estuarine lake was pumped into wetlands, and inflow and hydraulic residence time of the system was $500m^{3}{\~}1500m^{3}/day\;and\;2{\~}5$ days respectively. After 3 years operation plant-coverage was about $80~90\%$ from zero at initial stage even with no plantation. Average water quality of the influent in growing season was BOD_{5}\;3.96mg/L$, TSS 22.98 mg/L, T-N 3.29 mg/L, T-P 0.30 mg/L. The average removal rate of four wetlands for $BOD_{5},\;TSS,\;T-N\;and\;T-P$ in growing season was $24\%$, $62\%$, $54\%$, and $51\%$, respectively. And average water quality of the influent in winter season was $BOD_{5}$ 4.92 mg/L, TSS 12.47 mg/L, T-N 5.54 mg/L, and T-P 0.32 mg/L, respectively. The average removal rate of four wetlands for them was $-21\%$. $23\%$, $33\%$, and $53\%$, respectively. The reason of higher BOD_{5} effluent concentration in winter season might be that low temperature restrained microorganism activity and a organic body from the withered plant and algae was flown out. Except the result of $BOD_{5}$, the effectiveness of water quality improvement in winter season was satisfactory for treating polluted stream waters, and $BOD_{5}$ variation was within the range of background concentration. Performance of the experimental system was compared with existing data base (NADB), and it was within the range of general system performance. Overall, the wetland system was found to be satisfactory for NPS control such as improvement of polluted stream water.

• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.141-147
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• 2008

This study was aimed to develop an instrument for real-time measurement of fluid conductance and to investigate the hydrodynamics of dentinal fluid. The instrument consisted of three parts; (1) a glass capillary and a photo sensor for detection of fluid movement, (2) a servo-motor, a lead screw and a ball nut for tracking of fluid movement, (3) a rotary encoder and software for data processing. To observe the blocking effect of dentinal fluid movement, oxalate gel and self-etch adhesive agent were used. BisBlock (Bisco) and Clearfil SE Bond (Kuraray) were applied to the occlusal dentin surface of extracted human teeth. Using this new device, the fluid movement was measured and compared between before and after each agent was applied. The instrument was able to measure dentinal fluid movement with a high resolution (0.196 nL) and the flow occurred with a rate of 0.84 to 15.2 nL/s before treatment. After BisBlock or Clearfil SE Bond was used, the fluid movement was decreased by 39.8 to 89.6%.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.845-851
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• 1998

In order to manage the water quality from the flowing streams in Cheju Island, the characteristics of water quality was investigated from August, 1996 to May, 1997 and the pollutant loadings for future were estimated from the watershed at each stream. Comparing the mean concentrations of each water quality with the criterion of water quality in river, it was under I class except for Changgo Stream, for DO, under I class at the whole station for SS and under II class for BOD. As the pollutant loadings at each stream in 2020 is compared with those in 1996, the estimated results are as follows : 1) for BOD, 59% at Donghong Stream, 24% at Yeonoe Stream, 44% at Ohngpo Stream and 57% at Changgo Stream. 2) for T-N, 91% at Donghong Stream, 76% at Yeonoe Stream, 63% at Ohngpo Stream and 89% at Changgo Stream. 3) for T-P, 69% at Donghong Stream, 42% at Yeonoe Stream, 45% at Ohngpo Stream and 73% at Changgo Stream. The point source loadings discharged through combined sewer could be treated at sewage treatment plant. However, the expected slow decreasing rate of BOD, T-N, and T-P loadings is due to the part of untreated nonpoint source loadings. Nonpoint source loading overflow typically occurs when the flow of stormwater combined with sewage exceeds the capacity of the interceptor sewers. Since most of the sewers used in Cheju Island are the combined sewers, the combined overflow sewage is bypassed into the receiving water area after a rainstorm. Therefore, a means to control nonpoint source loadings should be considered for the river and marine water quality management.

• Korean Journal of Pharmacognosy
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• v.45 no.1
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• pp.84-87
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• 2014

A high performance liquid chromatography (HPLC) method for the quantitation of ellagic acid in Nymphaea tetragona was developed for the quality control of functional cosmetic ingredient, the extract of N. tetragona. Separation and quantitation were successfully achieved with a Kromasil C18 column ($5{\mu}m$, $250mm{\times}4.6mm$, i.d.) by isocratic elution of a mixture of acetonitrile containing 0.1% trifluoroacetic acid and water containing 0.03% phosphoric acid at a flow rate of 1.0 ml/min. The UV detector was used for the detection and the wavelength for quantitation was set at 254 nm. The presence of ellagic acid in the extract was determined by comparison of retention time and spiking with authentic standard. Analytical results showed good linearity ($R^2=0.99996$) in relatively wide concentration ranges. The R.S.D. for precision test was less than 3.0%. Recovery of the compound was 98.55~101.72% with R.S.D values less than 4.0%. In conclusion, this method has been successfully applied to the determination of ellagic acid in N. tetragona.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.461-466
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• 2011

The feasibility of utilizing food waste leachate as an external carbon source was tested to enhance biological nutrient removal from an industrial wastewater with an average flow rate of $164,800m^3/d$ and a low carbon/nitrogen ratio of 2.8. A considerable improvement in the removal of nitrogen and phosphorus was observed when a certain amount of the leachate, ranging from 70 to $142m^3/d$, was supplemented to the biological industrial wastewater treatment process. The addition of the leachate led to an increase in the BOD/N ratio (4.5) and the removal efficiency of nutritents from 29.7% to 71.7% for nitrogen and from 34.8% to 65.6% for phosphorus. However, an excessive dose of the leachate that significantly exceeded $120m^3/d$ caused serious operational problems, like oil-layer formation in the grit chamber and scum layer in the primary clarifier. Thus, an supplement of food waste leachate at a dose acceptable to an existing facilities can be a practical and effective means to enhance the nutrient removal from industrial wastewater and to dispose of the food waste leachate.