• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1087-1093
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• 2010

Autotrophic denitrification is known as an effective and economical alternative for heterotrophic denitrification using external carbon sources such as methanol. In this study, we evaluated design and operation parameters for a sulfur denitrification reactor (SDR) treating high strength nitrogen wastewater. The SDR was filled with spherical sulfur media in connected to a pilot-scale nutrient removal process (daily flow rate, $Q=18\;m^3/d$) using moving spongy media. Total nitrogen (TN) concentration of the final effluent was below the 7.0 mg TN/L because nitrate was additionally removed through autotrophic denitrificationin without adding alkalinity (initial alkalinity was $169.4{\pm}20.8\;mg$ $CaCO_3$/L). During the test period, 60~80% of nitrogen in the influent was removed even in low temperature (below $15^{\circ}C$). The alkalinity consumption for nitrate removal in SDR was $4.09{\pm}1.29$ g $CaCO_3/g$ ${NO_3}^-$-N, and the residual alkalinity of influent of SDR was higher than that of theoretical requirements for full conversion of nitrate. The consumption of sulfur was 943.8 g S/d and it was 2.4 times higher than theoretical value (400.1 g S/d) due to abrasion and loss of sulfur media in backwash, etc.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.3
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• pp.461-467
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• 2016

In order to install the floating transport type wind-turbine foundation, water pumping is used to sink the foundation. During this process, its mass and center of gravity, and buoyancy center become continuously changed so that the dynamic stability of the floating foundation become unstable. Dynamic stability analysis of the floating foundation is a complex problem since it should take into account not only the environmental wave, wind, and current loads but also its weight change effect simultaneously considering six-degree-of-freedom motion. In this study, advanced numerical method based on the coupled computational fluid dynamics (CFD) and multi-body dynamics (MBD) approach has been applied to the dynamic stability analysis of the floating foundation. The sloshing effect of foundation internal water is also considered and the floating dynamic characteristics are numerically investigated in detail.

• Analytical Science and Technology
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• v.20 no.2
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• pp.138-146
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• 2007

A simple and sensitive method for the determination of paroxetine in canine plasma was developed and validated by liquid-liquid extraction and liquid chromatography-tandem mass spectrometry (LC-/MS/MS). Fluoxetine was used as an internal standard. Paroxetine and internal standard in plasma samples were extracted using TBME (tert-butyl methyl ether). A centrifuged upper layer was then evaporated and reconstituted with mobile phase of 50% acetonitrile adjusted to pH 3 by formic acid. The reconstituted samples were injected into a Capcell Pak UG120 ($2.0{\times}150mm$, $5{\mu}m$) column. Using MS/MS with SRM (selective reaction monitoring) mode, the transitions (precursor to product) monitored were m/z $330{\rightarrow}192$ for paroxetine, and m/z $310{\rightarrow}148$ for internal standard. Linear detection responses were obtained for paroxetine concentration range of 0.02~5 ng/mL. A correlation coefficient of linear regression ($R^2$) was 0.9993. Detection of paroxetine in canine plasma was accurate and precise, with limit of quantification at 0.02 ng/mL. The method has been successfully applied to pharmacokinetic study of paroxetine in healthy beagle dogs.

• Journal of Animal Science and Technology
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• v.45 no.5
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• pp.875-884
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• 2003

Operational parameters for struvite crystallization, as a process to recover nitrogen and phosphorus resources from animal wastewater, were studied in this research. Crystallization distinctive of NH$_4$-N and PO$_4$$^{3-}$ in accordance to chemical sources, influent pH, aeration and stirring was examined using 2L of working volume of struvite reactor. Also, to find an effective treatment process combining with electrolysis method, removal characteristics of NH$_4$-N and PO$_4$$^{3-}$ in 6 different processes was tested. As chemical sources for the derivation of struvite formation, MgSO$_4$ and MgCl$_2$ were superior to CaCO$_3$ and CaCl$_2$. From experiment which was conducted to know the effects of aeration and stirring on struvite formation, it was revealed that aeration stimulated the crystallization reaction by inducing faster pH increase. While 90% of P removal was achieved within 1 hour under aeration, 14 hours was consumed under stirring condition. Struvite formation under aeration was affected by influent pH. No crystallization was observed at pH 5 level, but active crystallization reaction was induced over pH 6.0. 95% of P removal by struvite formation at pH 6, 7 and 9 was achieved within 3h, 2h and 10 min., respectively. However, over pH 10, operational problem due to excessive foam formation occurred, and blunting of crystallization reaction was observed at pH 11. When consider the pH range of animal wastewater, pH 7 to 9, efficient struvite formation could be achieved by simple aeration, without any chemical usage for pH adjustment. Among tested processes, the treatment process which electrolyzing the supernatant from struvite reactor, providing air to both reactors, showed best pollutant removal efficiencies. In this combined process, the removal efficiencies of NH$_4$-N and PO$_4$$^{3-}$ was 86% and 98%, respectively, and 92.4% of color removal was obtained.

• Korean Journal of Medicinal Crop Science
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• v.8 no.2
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• pp.123-128
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• 2000

This study was carried out to determine factors affecting on the mass propagation of Rehmannia glutinosa seedlings in bioreactor culture. Air-lift type bioreactor was more compatible to shoot formation than stirrer type. Fifty grams(90 stem explants) of inoculum in 1.5L medium was placed into 2.5L bioreactor with aeration rate of 0.5 v.v.m., which was proper for effective shoot formation. Adding MES as pH buffer to culture medium increased the numbers of shoot formation. Adding 5g/l of anti-vitrifying agent into culture medium was highly effective for diminishing the rate of vitrification in shoots formed.

• Analytical Science and Technology
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• v.22 no.6
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• pp.514-518
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• 2009

Coenzyme $Q_{10}$($CoQ_{10}$), a vitamin E-like substance, represents a components of the complex antioxidant system of the human organism. $CoQ_{10}$ levels in human plasma were determined by high performance liquid chromatography (HPLC) with UV detection. It was dissociated from lipoproteins by methanol and extracted into n-hexane with liquid-liquid extraction procedure, after centrifugation, the supernatant was dried under nitrogen gas stream. The residue was dissolved in the absolute ethanol. Determination of $CoQ_{10}$ was performed on a $C_{18}$ reversed-phase analytical column with ultraviolet detection at 275 nm and the mobile phase containing 15% (v/v) ethanol in methanol at a flow rate of 1.7 mL/min. The low limit of quantitation was 0.02 mg/L (S/N=10), the linearity between the concentration and peak height is from 0.1 to 2.0 mg/L. Twenty-four randomly selected plasma samples from apparently healthy, 27 to 44 year old individuals (males and females) were analyzed for total $CoQ_{10}$. The average level in these subjects was $0.62{\pm}0.13mg/L$ with the range of 0.41-0.98 mg/L. This method has a specific and a sufficient limit of quantitation (LOQ) for analysis of $CoQ_{10}$ in human plasma in both a clinical study and research at laboratories.

• Polymer(Korea)
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• v.32 no.4
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• pp.372-376
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• 2008

Vacuum deposited 4,4',4"-tris(N-(2-naphthyl)-N-phenylamino)-triphenylamine (2-TNATA), used as a hole injection (HIL) material in OLEDs, is placed as a thin interlayer between indium tin oxide (ITO) electrode and a hole transporting layer (HTL) in the devices. C60-doped 2-TNATA:C60 (20 wt%) film was formed via co-evaporation process and molecular ordering and topology of 2-TNATA:C60 films were investigated using XRD and AFM. The J-V, L-V and current efficiency of multi-layered devices were characterized as well. Vacuum-deposited C60 film was molecularly oriented, but neither was 2-TNATA:C60 film due to the uniform dispersion of C60 molecules in the film. By using C60-doped 2-TNATA:C60 film as a HIL, the current density and luminance of a multi-layered ITO/2-TNATA:C60/NPD/$Alq_3$/LiF/Al device were significantly increased and the current efficiency of the device was increased from 4.7 to 6.7 cd/A in the present study.

• The Korean Journal of Mycology
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• v.6 no.1
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• pp.29-41
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• 1978

This study aims to brew apple wine containing lower concentration of alcohol by fermentation and to retain $CO_2$ gas in apple wine, and investigation for the possibility of storage at room temperature was performed. A Saccharomyces sp. was proved to be acceptable for production of base wine as its higher fermentation rate at $20{\sim}25^{\circ}C$. However, B-2 was most reasonable for post-fermentation of apple wine as this strain strongly ferments sugars at low temperature $(4^{\circ}C)$. The yield of apple juice increased by maceration of apple pulps. The yield was about 5 % more than that of the unmacerated juice, whereas acid content was decreased by 10% compared with control. When stored apple wine containing 9% alcobol was introduced $1{\sim}3%$ sucrose at $7{\sim}8^{\circ}C$ for 100 days or more, the $CO_2$ pressure of apple wine in bottle shows $3kg/cm^2$ by bottle-pressure meter. It showed good storage of the wine at room temperature. $CO_2$ gas pressure in apple wine containing 6% alcohol, $5{\sim}10%$ hop extract, and 2% sugar was $2kg/cm^2$, he result also showed possibility of storage. Whereas 6% concentration of alcoholic apple wine without hop extract caused unusual fermentation during storage at the same condition. The desirable conditions for high quality apple wine should have $CO_2$ pressure of $2kg/cm^2$ or more and should be added $1{\sim}2% sugar to base wine. From these results, it can be concluded that the brewing of lower alcoholic apple wine is possible.

• Journal of Energy Engineering
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• v.8 no.2
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• pp.309-316
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• 1999

A numerical study for the turbulent reacting flow in an orimulsion gasifier has been carried out to analyze the characteristics of chemical reaction by orimulsion droplets. In this study, our interest has been focused on the effect of oxidizer to orimulsion ratio, which is one of the key parameters of gasification operation, as well as on the distribution of chemical species. In addition, we have conducted numerical calculations to understand the effect of droplet size, spray angle and injection velocity of fuel so as to acquire the basic information on the operating range of orimulsion gasifier. The result of numerical calculations showed that the gas composition of CO and H$_2$concentrations was the highest when the oxidizer to orimulsion ratio was about 0.88 and the reactivity of orimulsion increased as the droplet size reduced with proper spray angle. Also, we have carried out the analysis on the orimulsion gasification in the 100 ton/day-scale gasifier based upon the prior study in order to obtain the basic data for the proper operating condition using orimulsion feed.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.63-68
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• 2008

This paper describes about the simulation and the experimental results of optical cavity with curved mirror surface and vertical mirror surface to improve the light intensity and efficiency of the optical sensors. When we use the vertical mirror surface, the distribution of light reached to the filter surface of detector shows an elliptical shape. Whereas, the curved mirror surface focuses the light into circular shape. Therefore, due to focusing effects in case of using curved mirror surface, the light intensity per unit area has been improved. Consequently, the output voltage of gas sensor has been expected to increase. Based upon the simulation, the experiment of gas sensor has been conducted with $CO_2$ gas from 0ppm to 2,500 ppm at 250 ppm step and $25^{\circ}C$, 45%R.H. ambient. The output voltage of gas sensor that has a curved mirror surface increases approximately 200 mV than that of vertical mirror surface.