• Journal of Animal Environmental Science
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• v.18 no.3
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• pp.145-150
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• 2012

This study was conducted to measure methane ($CH_4$) and nitrous oxide ($N_2O$) emissions from the 6 month old litter stockpile used for korean native cattle (Hanwoo) from August 3, 2007 to October 4, 2007. Daily mean $CH_4$ emissions was peaked to 273.013 ${\mu}g\;m^{-2}\;s^{-1}$ (SE : ${\pm}1.047{\mu}g\;m^{-2}\;s^{-1}$) on first day and then gradually decreased to 2.309 ${\mu}g\;m^{-2}\;s^{-1}$ (SE : ${\pm}0.061{\mu}g\;m^{-2}\;s^{-1}$) at the end of this experiment. Daily mean $N_2O$ emissions was as little as 0.269 ${\mu}g\;m^{-2}\;s^{-1}$ (SE : ${\pm}0.018{\mu}g\;m^{-2}\;s^{-1}$) on first day, but exponentially increased up to 3.569 ${\mu}g\;m^{-2}\;s^{-1}$ (SE : ${\pm}0.454{\mu}g\;m^{-2}\;s^{-1}$) on 43rd day and then slowly decreased to 1.888 ${\mu}g\;m^{-2}\;s^{-1}$ (SE : ${\pm}0.012{\mu}g\;m^{-2}\;s^{-1}$) at the end of this experiment. Carbon dioxide equivalent ($CO_2$-eq), calculated by global warming potentials of $CH_4$ or $N_2O$, of $CH_4$ on first day occupied approximately 99% of sum of $CO_2$-eq of $CH_4$ and $N_2O$. Methane emissions decreased and $N_2O$ emissions increased so that $CO_2$-eq ratio of $CH_4$ to $N_2O$ was 50:50 on 34th day. The effect of $N_2O$ on the ratio was increase thereafter. The ratio of daily mean $CH_4$ and $N_2O$ emissions to daily error of the mean was calculated to find daily fluctuation of $CH_4$ and $N_2O$ emissions. The ratio of $CH_4$ was less than 1.0% till 11th day but increased to 10.9% on 57th day. The ratio of $N_2O$ (0.4%~51.0%) was higher than that of $CH_4$, showing high in early stage and then gradually decrease, which was different from the pattern of $CH_4$. The ratio of daily mean emissions to daily error of the mean was little in case of active $CH_4$ or $N_2O$ generation period, which would be caused by the temporal and spatial heterogeneity of composting process. Hence more air supply on early stage to decrease $CH_4$ generation and proper turning to reduce spatial heterogeneity are needed to mitigate greenhouse gas emissions.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.4
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• pp.303-313
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• 2015

Titrated extract of Centella asiatica (TECA), which is poorly soluble in water is well known for wound healing and anti wrinkle agent. This study was conducted to find the optimum condition for the preparation of water in oil in water ($W_1/O/W_2$) emulsion containing TECA. Solubility of TECA were measured by UV spectrophotometer. 2.55 g of TECA was dissolved in solution composed of dipropylene glycol (40.0 g), ethanol (20.0 g), and water (10.0 g). Factors affecting stability of the emulsions ($W_1/O$, $W_1/O/W_2$) was investigated. The optimum conditions for the preparation of $W_1/O$ emulsion was composed of dipropylene glycol : ethanol : water : TECA in a weight ratio of 40.0 : 20.0 : 10.0 : 2.5 for water phase and squalane : cetyl PEG/PPG-10/1 dimethicone : cetearyl alcohol in a weight ratio of 22.5 : 4.0 : 2.5 for oil phase. The optimum conditions for the preparation of $W_1/O/W_2$ multiple emulsion was composed of water : $W_1/O$ emulsion : polysorbate 80 : carbomer : triethanolamine in a weight ratio of 55.8 : 40.0 : 4.0 : 0.1 : 0.1.

• Journal of Food Hygiene and Safety
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• v.20 no.1
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• pp.48-52
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• 2005

This study was investigated to determine the antimicrobial activity of ethanol extract of green tea, and of solvent fractionated ethanol extract on Escherichia coli O157:H7. MIC value of ethanol extracts and solvent fractionated ethanol extract (hexane, ethyl-acetate, chloroform and water) were $2000{\mu}g/ml,\;0,\;500{\mu}g/ml,\;2000{\mu}g/ml,\;1000{\mu}g/ml$, respectively. The antimicrobial activity of ethyl acetate fraction against E. coli O157 :H7 ranged from $250-2000{\mu}g/disk$. The antimicrobial activity was significantly increased as concentration dependent. When E. coli O157:H7 was pH-adjusted TSB containing $1000{\mu}g/ml$ ethyl acetate, E. coli O157:H7 was significantly inhibited at initial pH of 10, whereas the pathogen grew well in the presence of pH 4.5-pH 9. The inhibitory effect of the ethyl acetate fraction on the growth of E. coli O157 :H7 was investigated. Growth of both strain in the tested conditions were rapidly occurred up to 12 h, but no growth was occurred in the presence of $250-1000{\mu}g/mL$ of ethyl acetate fraction for 72 h.

• Korean Journal of Logic
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• v.21 no.1
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• pp.97-133
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• 2018

In his unpublished article, "Is Mathematics Syntax of Language?," $G{\ddot{o}}del$ criticizes what he calls the 'syntactical interpretation' of mathematics by Carnap. Park, Chun, Awodey and Carus, Ricketts, and Tennant have all reconstructed $G{\ddot{o}}del^{\prime}s$ arguments in various ways and explored Carnap's possible responses. This paper first recreates $G{\ddot{o}}del$ and Carnap's debate about the nature of mathematics. After criticizing most existing reconstructions, I claim to make the following contributions. First, the 'language relativity' several scholars have attributed to Carnap is exaggerated. Rather, the essence of $G{\ddot{o}}del^{\prime}s$ critique is the applicability of mathematics and the argument based on 'expectability'. Thus, Carnap's response to $G{\ddot{o}}del$ must be found in how he saw the application of mathematics, especially its application to science. I argue that the 'correspondence principle' of Carnap, which has been overlooked in the existing discussions, plays a key role in the application of mathematics. Finally, the real implications of $G{\ddot{o}}del^{\prime}s$ incompleteness theorems - the inexhaustibility of mathematics - turn out to be what both $G{\ddot{o}}del$ and Carnap agree about.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.387-390
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• 1999

To improve the cycle performance LiM $n_2$ $O_4$as the cathode of 4V class lithium secondary batteries, the cathode properties of the cubic spinel phases LiM $g_{x}$ /M $n_{2-x}$/ $O_4$ synthesized at 80$0^{\circ}C$ were examined. All cathode material showed spinel phase based on cubic phase in X-ray diffraction however. other peaks gradually exhibited and became intense with the increase of x value in LiM $g_{x}$ /M $n_{2-x}$/ $O_4$. The cycle performance of the LiM $g_{x}$ /M $n_{2-x}$/ $O_4$was improved by the substitution of $Mg^{2+}$ for M $n^{3+}$ in the octahedral sites. Specially LiM $g_{0.1}$/M $n_{1.9}$ / $O_4$cathode materials showed the charge and discharge capacity of about 130~125mAh/g at first cycle and about 105mAh/g after 50th cycle. It is excellent than that of pure LiM $n_{2}$/ $O_4$ which 125mAh/g at first cycle 70mAh/g at 50th. In addition cathode material prepared at 80$0^{\circ}C$ for 24hr and 42hr in the charge and discharge capapcity as well as the cycle stability.ility.y.y.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.143-146
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• 2007

Birnessite-type manganese dioxide($MnO_2$) was coated uniformly onto carbon nanotubes (CNTs) through a spontaneous direct redox reaction between CNTs and permanganate ions($MnO_4\;^-$). The initial specific capacitance of the $MnO_2/CNT$ nanocomposite in an organic electrolyte at a large current density of 1 A/g was 250 F/g, which is equivalent to 139 mAh/g based on the total weight of the electrode material including the electroactive material, conducting agent and binder. The specific capacitance of the $MnO_2$ in the $MnO_2/CNT$ nanocomposite was as high as 580 F/g (320 mAh/g), indicating excellent electrochemical utilization of the $MnO_2$. The addition of CNTs as a conducting agent can improve the high rate capability of $MnO_2/CNT$ nanocomposite considerably. An analysis of the in-situ X-ray absorption near-edge structure (XANES) showed an improvement in the structural and electrochemical reversibility of the $MnO_2/CNT$ nanocomposite by heat-treatment.

• Journal of the Korean institute of surface engineering
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• v.32 no.6
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• pp.647-657
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• 1999

Due to the inherently poor adhesion strength of Cu-based leadframe/EMC (Epoxy Molding Compound) interface, popcorn cracking of thin plastic packages frequently occurs during the solder reflow process. In the present work, in order to enhance the adhesion strength of Cu-based leadframe/EMC interface, black-oxide layer was formed on the leadframe surface by chemical oxidation of leadframe, and then oxidized leadframe sheets were molded with EMC and machined to form SDCB (Sandwiched Double-Cantilever Beam) and SBN (Sandwiched Brazil-Nut) specimens. SDCB and SBN specimens were designed to measure the adhesion strength between leadframe and EMC in terms of critical energy-release rate under quasi-Mode I ($G_{IC}$ ) and mixed Mode loading ($G_{C}$ /) conditions, respectively. Results showed that black-oxide treatment of Cu-based leadframe initially introduced pebble-like X$C_2$O crystals with smooth facets on its surface, and after the full growth of $Cu_2$O layer, acicular CuO crystals were formed atop of the $Cu_2$O layer. According to the result of SDCB test, $Cu_2$O crystals on the leadframe surface did not increase ($G_{IC}$), however, acicular CuO crystals on the $Cu_2$O layer enhanced $G_{IC}$ considerably. The main reason for the adhesion improvement seems to be associated with the adhesion of CuO to EMC by mechanical interlocking mechanism. On the other hand, as the Mode II component increased, $G_{C}$ was increased, and when the phase angle was -34$^{\circ}$, crack Kinking into EMC was occured.d.

• Clean Technology
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• v.26 no.4
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• pp.304-310
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• 2020

In order to apply a photocatalyst (TiO2) to various building materials, TiO2-mayenite was prepared in this study. The TiO2 was synthesized using the sol-gel method by fixing titanium isopropoxide (TTIP) and urea at a ratio of 1 : 1. Later, they were calcined in a temperature range of 400-700 ℃ to analyze the properties according to temperature. BET, TGA, and XRD were used to analyze the physical and chemical properties of TiO2. The nitrogen oxide removal test was confirmed by measuring the change in the concentration of NO for 1 h according to KS L ISO 22197-1. The prepared TiO2 samples exhibited an anatase crystal structure below 600 ℃, and TiO2 (urea)-400 showed the highest nitrogen oxide removal rate at 2.35 µmol h-1. TiO2-mayenite was prepared using two methods: spraying TiO2 dispersion solution (s/s) and sol-gel solution (g/s). Through BET and XRD analysis, it was found that 5-TiO2 (g/s) prepared by spraying a sol-gel solution has maintained its crystallinity even after heat treatment. Also, 5-TiO2 (g/s)-500 showed the highest removal rate of 0.55 µmol h-1 in the nitrogen oxide removal test. To prepare TiO2-mayenite, it was confirmed that mayenite should be blended with TiO2 in a sol-gel state to maintain the crystal structure and exhibit a high nitrogen oxide removal rate.

• Rubber Technology
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• v.6 no.2
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• pp.91-98
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• 2005

Nano-sized cathode materials for high power lithium ion polymer battery are easily and economically prepared using united eutectic self-mixing method without any artificial mixing procedures of reactants and ultra-miniaturization of products. While the micro-sized $LiNi_{0.7}Co_{0.3}O_2$ exhibits the discharge capacities of 167.8 mAh/g at 0.1C and 142.5 mAh/g at 3.0C, those of the nano-sized $LiNi_{0.7}Co_{0.3}O_2$ are 170.8 mAh/g at 0.1C and 159.3 mAh/g at 3.0C. In the case of $LiCoO_2$, the micro-sized $LiCoO_2$ exhibits the discharge capacities of 134.8 mAh/g at 0.1C and 118.6 mAh/g at 5.0C. Differently, the nano-sized $LiCoO_2$ exhibits the discharge capacities of 137.2 mAh/g at 0.1C and 131.7 mAh/g at 5.0C.

• Bulletin of the Korean Chemical Society
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• v.32 no.10
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• pp.3682-3686
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• 2011

The electrochemical properties of lithium-sulfur batteries with binary electrolytes based on DME and DOL, TEGDME and DOL mixed solvent containing $LiClO_4$, LiTFSI, and LiTF salts were investigated. The ionic conductivity of 1M LiTFSI and $LiClO_4$ electrolytes based on TEGDME and DOL increased as the volume ratio of DOL solvent increased, because DOL effectively reduces the viscosity of the above electrolytes medium under the same salts concentration. The first discharge capacity of lithium-sulfur batteries in the DME and DOL-based electrolyte followed this order: LiTFSI (1,000 mAh/g) > LiTF (850 mAh/g) > $LiClO_4$ (750 mAh/g). In case of the electrolyte based on TEGDME and DOL, the first discharge capacity of batteries followed this order: $LiClO_4$ (1,030 mAh/g) > LiTF (770 mAh/g) > LiTFSI (750 mAh/g). The cyclic efficiency of lithium-sulfur batteries at 1M $LiClO_4$ electrolytes is higher than that of batteries at other lithium salts-based electrolytes. Lithium-sulfur battery showed discharge capacity of 550 mAh/g until 20 cycles at all electrolytes based on DME and DOL solvent. By contrast, the discharge capacity of batteries was about 450 mAh/g at 1M LiTFSI and LiTF electrolytes based on TEGDME and DOL solvent after 20 cycles.