• Journal of Environmental Science International
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• v.15 no.8
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• pp.727-735
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• 2006

In this study, the PHYTO-PAM-fluorometric method was used to evaluate the ETR$_{max}$ in terms of sensitivity to DIN/DIP against 14 microalgae: Prorocentrum micans, Heterocapsa triquetra, Gymnodinium impudicum, Cymnodinium catenatum, Amphidinium caterae, Chlorella vulgaris, Chroococcus minutus, Microcystis aeruginosa, Chlorella ellipsoidea, Nannochloris oculata, Oocystis lacustris, Chroomonas salina, Gloeocystis gigas, and Prymnessium parvum. We found that P. micans, H. triquetra, and A. caterae exposed to the maximum level of DIN/DIP were significantly smaller in the ETR$_{max}$ than that of the minimum and moderate mixture. Unlikely the ETR$_{max}$, the initial slope alpha was not significantly different at the level of 60 DIN/DIP. In G. catenatum, the moderate levels of 15 and 20 in DIN/DIP were found to be significantly different from the ETR$_{max}$ at Chl-Ch4. Gymnodinium impudicum had a higher value than that of the ETR$_{max}$ than that of dinoflagellates used in this study, ranging from 306.1 (Ch4, DIN/DIP: 10) to 520.1 (Ch4, DIN/DIP: 30). The ETR$_{max}$ value obtained from other microalgae was similar to C. impudicum at any of the ratios of DIN/DIP and channels. Consequently, the influence of offshore water current assures us of the suppression of photosynthesis and electron transport rate in dinoflagellates. Gymnodinium impudicum has not been researched in the area of red tides in Korea, but it will be enough to creat the massive algal blooms in the future because of higher potential photochemical availability.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1135-1138
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• 2009

Hollow Sn and Pb nanoparticles have been prepared by a rapid injection of an aqueous solution of $SnCl_2$- poly(vinylpyrrolidone) (PVP, surfactant) and $Pb(OAc)_2${\cdot}$3H_2O-PVP$ into an aqueous solution of sodium borohydride (reducing agent) in simple, one-pot reaction at room temperature under an argon atmosphere, respectively. The two hollow nanoparticles have been fully characterized by TEM, HRTEM, SAED, XRD, and EDX analyses. Upon exposure to air, the black Pb hollow nanoparticles are gradually transformed into a mixture of Pb, litharge (tetragonal PbO), massicot (orthorhombic PbO), and $Pb_5O_8$. The order and speed of mixing of the reactants between the metal precursor-PVP and the reductant solutions and stoichiometry of all the reactants are crucial factors for the formation of the two hollow nanocrystals. The Sn and Pb hollow nanoparticles were produced only when 1:(1.5-2) and 1:3 ratios of the Sn and Pb precursors to $NaBH_4$ were employed with a rapid injection, respectively.

• Journal of the Korean GEO-environmental Society
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• v.6 no.4
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• pp.5-12
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• 2005

In this study, the geotechnical applicability of permeable barriers that could filter the leachate from a landfill was evaluated. Specimens were cast from sand, loess and bentonite according to the specific weight ratios of them. A series of experiments are performed to determine the unconfined compressive strength and permeability of various mixing ratio of bentonite, loess, and sand. From the laboratory test, optimum mixing ratio that satisfied the regulations of unconfined compressive strength($5kgf/cm^2$) and coefficient of permeability ($10^{-3}{\sim}10^{-4}cm/sec$) in landfill was found when the weight ratio of sand and loess was 8:2 with 2% of bentonite. Using the laboratory test data and in situ test results, the applicability of the wall will be tested for various conditions.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.1
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• pp.47-58
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• 2014

The characteristics of flame shape, laminar burning velocity, emissions and heat flux of stagnation point in premixed impinging jet flame of syngas fuel with 10% hydrogen content were experimentally investigated. Also, the adiabatic temperature and burning velocity are calculated by Chemkin package with USC-II mechanism. The equivalence ratios(0.8~5.0) and dimensionless separation distance(2.0~5.0) with fixed Reynolds number(1800) are main parameters in this work. Different flame shapes and colors were observed for different impingement conditions. The experimental results of burning velocity by flame surface area have a consistent with previous works and numerical simulation of this work. The inner flame length could be predicted with the ratio of mixture velocity and burning velocity from a simple formulation by the laminar burning velocity definition. It has been observed that the heat fluxes at stagnation point are directly affected by the flame shape including the separation distance. The emission results in impinging flame of syngas fuel show that the characteristics of $NO_x$ emission traced well with adiabatic temperature trend and CO emission due to fuel rich condition increased continuously with respect to the equivalence ratio.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.71-74
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• 2007

With the changes of times the building materials tend to extend the demand for application under the special environment. Since high-ductile mortar is developed, the building materials show excellent performance like toughness, compression, tensile, and bending, etc. in the general concrete from the existing brittle point. And, recently they are widely used as repairing and reinforcing materials both at home and abroad because they are recognized as excellence like durability and fire-resistance. However, it is in a situation of creating problems in durability because it frequently happened deterioration of buildings that have already repaired and reinforced at a time when it requires reconstruction of recently deteriorated construction structure recently. Therefore, in this study improved with a more repair Material development and reinforcement of the second high-ductile mortar products for a variety of basic materials were presented want, research plans used include traditional repair materials and the newly developed PCM (polymer cement mortar) structural reinforcement type indicated that comparison. PCM analysis in order to present a rate depending on the types fiber 0, 1.2 and 2.0(%) at three levels and mixture water according to ratios of weight to Plain in the 2.0 and 1.85(kg) at two levels is set, the results were as follows. 1) This study has shown that PCM had excellent strain hardening behavior at the same time that the bending stress increased according to the fiber contents. 2) This study has shown that it had the durability performance due to the high substance transmission according to the fiber contents.

• Computers and Concrete
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• v.19 no.2
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• pp.153-159
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• 2017

In this study, the strength properties of alkali-activated silica fume (SF) mortars were investigated. The crushed limestone sand with maximum size of 0-5 mm and the sodium meta silicate ($Na_2SiO_3$) used to activate the binders were kept constant in the mortar mixtures. The mortar specimens using the replacement ratios of 0, 25, 50, 75 and 100% SF by weight of cement together with $Na_2SiO_3$ at a constant rate were produced in addition to the control mortar produced by only cement. Moreover, the mortar specimens using the replacement ratio of 4% titanium dioxide ($TiO_2$) by weight of cement in the same mixture proportions were produced. The prismatic specimens produced from eleven different mixtures were de-moulded after a day, and the wet or dry cure was applied on the produced specimens at laboratory condition until the specimens were used for flexural strength ($f_{fs}$) and compressive strength ($f_c$) measurement at the ages of 7, 28 and 56 days. The $f_{fs}$ and $f_c$ values of mortars applied the wet or dry cure were compared with the results of control mortar. The findings revealed that the $f_c$ results of the alkali activated 50% SF mortars were higher than that of mortar produced with Portland cement only. It was found that the $f_{fs}$ and $f_c$ of alkali-activated SF mortars cured in dry condition was averagely 4% lower than that of alkali-activated SF mortars cured in wet condition.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.529-534
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• 1996

A high-performance liquid chromatographic (HPLC) assay has been developed for the determination of ketorolac in human serum using a new extraction method with a good recovery. Human serum samples (1.0 ml) spiked with known concentrations of ketorolac tromethamine and 10${\mu}g$ of ketoprofen as the internal standard (IS) were acidified with 200${\mu}l$ of 1 N HCl and extracted with 7 ml of n-hexane-ether (7:3 v/v). Extracts were centrifuged and organic layer was back-extracted with 400${\mu}l$ of 0.1% tromethamine solution. Twenty .mu.l of centrifuged aqueous layer was injected onto a reversed-phase octyl column and eluted with a mixture of acetonitrile, water, methanol, and triethylamine [35:55:10:0.1 (v/v), pH 3.0] at a flow rate of 1.0 ml/min. Ultraviolet detection of ketorolac and IS was carried out at 300 nm. The calibration curve obtained using peak area ratios showed a good linearity (in concentration range 10-150 ng/ml $r^2$=O.9944; in range 50-2000 ng/ml, r$^{2}$=0.9998). The mean intra-day accuracy and precision for this HPLC method were found to be 3.6 and 3.7%, respectively. The mean inter-day accuracy and precision were found to be 4.0 and 3.7%, respectively, in the concentration range 50-2000 ng/ml. The recovery of ketorolac from serum was 92.0 $({\pm}5.7)$ % at the concentration of 100 ng/ml. This method proved to be readily applicable to the assay of ketorolac in human serum.

• Journal of Environmental Health Sciences
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• v.22 no.4
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• pp.82-90
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• 1996

This study was performed to find the optimum mixing ratio of paper waste in composting of mixture of swine feces and newspaper. Using the experimental setting of aeration rate which was found in the experiment carried out priorly, and moisture contents reported in other literature, just the initial C:N ratios were differentiated by mixing different amount of newspaper with the same amount of swine feces. This study was carried out by operating 4 experimental cornposting reactors of bench scale for 3 weeks. The followings are the conclusions that were derived from this study. 1. During composting reaction, the C:N ratio of each cornposter was decreased. Degree of decrease was in order of run 3, run 2, run 4, and run 1 of which initial C:N ratio was 30, 25, 35, and 20 respectively. All of the final composts were found to be completed composting reaction. 2. Ash contents of each reactor increased rapidly in order of run 3, run 2, run 4, and run 1. The absolute values of quadratic effect coefficients of each second order regression function was 0.059, 0.038, 0.032, and 0.030 respectively. Ash contents evolution trend had a linear correlation with the C:N ratio trend. (r=-0.96932, p<0.05) 3. The range of highest temperatures reached during composting was 47.2-53.5$\circ$C. Those were not significantly different from one another. Thermophilic temperatures were maintained in the range of 48-108 hours. 4. Contents of heavy metal detected in the final compost were lower than those of Korean and European standards. 5. Concentration range of Nitrogen in the final compost was 1.11-2.27%, and that of phosphorus was 8.40-10.70 mg/kg. 6. The optimum C:N ratio which has been proposed without the consideration of types of bulking agents should be re-examined. Biodegradabilities of each bulking agents was thought to be important factor when determining the optimum initial C:N ratio for cornposting.

• Journal of Pharmaceutical Investigation
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• v.34 no.4
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• pp.289-297
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• 2004

Acyclovir (ACV) is one of the most effective and selective agents against viruses of the herpes group. Because of low solubility, bioavailability of ACV has shown below 30% with oral dosage form. In our previous study, we reported that the fabrication of solid dispersion of ACV was possible and the solid dispersion of ACV and PVP was the most useful in all samples. In this study, we examined the effect of mixture ratio of polymers (PEG and PVP) to ACV. Solubility of ACV was dramatically increased up to 25 mg/ml in $80^{\circ}C$ distilled water. So water was used as a solvent to eliminate problem of residual solvent. Spray drying method was used for the solid dispersion of ACV as solvent extraction. Different scanning calorimeter was used to check degradation of drug. Polymer carriers were PEG 6,000 and PVP. In summary, ACV-PVP (1:3) showed the best solubility in distilled water.

• Journal of the Korean Society of Combustion
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• v.19 no.1
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• pp.17-28
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• 2014

In this study, the laminar burning velocity of syngas fuel($H_2/CO$) and flame structure with various hydrogen contents were studied using both experimental measurements and detailed kinetic analysis. The laminar burning velocities were measured by the angle method of Bunsen flame configuration and the numerical calculations including chemical kinetic analysis were made using CHEMKIN Package with USC-Mech II. A wide range of syngas mixture compositions such as $H_2$ : CO = 10 : 90, 25 : 75, 50 : 50, 75:25 and equivalence ratios from lean condition of 0.5 to rich condition of 5.0 have been considered. The experimental results of burning velocity were in good agreement with previous other research data and numerical simulation. Also, it was shown that the experimental measurements of laminar burning velocity linearly increased with the increment of $H_2$ content although the burning velocity of hydrogen is faster than the carbon monoxide above 10 times. This phenomenon is attributed to the rapid production of hydrogen related radicals such as H radical at the early stage of combustion, which is confirmed the linear increase of radical concentrations on kinetic analysis. Particular concerns in this study are the characteristics of burning velocity and flame structure different from lean condition for rich condition. The decrease of OH radicals and double peaks are observed with $H_2$ content in rich condition once $H_2$ fraction exceeds over threshold.