• Journal of Environmental Science International
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• v.23 no.6
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• pp.1157-1163
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• 2014

The solid phase extractant (PVC-D2EHPA bead) was prepared by immobilizing di-2-ethylhexyl-phosphoric acid (D2EHPA) with polyvinyl chloride (PVC). The prepared PVC-D2EHPA beads were characterized by using fourier transform infrared spectrometer (FTIR) and scanning electron microscopy (SEM). The removal experiments of Cu(II) by PVC-D2EHPA beads conducted batchwise. The removal kinetics of Cu(II) was found to follow the pseudo-second-order model. The equilibrium data fitted well with Langmuir isotherm model and the maximum removal capacity was 2.6 mg/g at $20^{\circ}C$. The optimum pH region was in the range of 3.5 to 6. and the standard free energy (${\Delta}G^{\circ}$) was between -4.67~-4.98 kJ/mol, indicating the spontaneous nature of Cu(II) removal by PVC-D2EHPA beads.

• Journal of the Korean institute of surface engineering
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• v.36 no.2
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• pp.200-205
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• 2003

Thermoelectric p-type $Fe_{0.98}$ $Mn_{ 0.02}$$Si_2$ bulk specimens have been produced by mechanical alloying and consolidation by vacuum hot pressing. The subsequent isothermal annealing was not able to fully transform the mestastable as -milled powders into the $\beta$ $-FeSi_2$ phase, so that the obtained matrix consisted of not only thermoelectric semiconducting $\beta$-FeSi$_2$ but also some residual, untransformed metallic $\alpha$ $- Fe_2$$Si_{ 5}$ and $\varepsilon$-FeSi mixtures. Interestingly, $\beta$ - $FeSi_2$ was more easily obtained in the low density specimen when compared to the high density specimen. The oxidation at 700 and $800^{\circ}C$ in air led to the phase transformation of the above described iron - silicides and the formation of a thin silica surface layer.

• Korean Journal of Materials Research
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• v.21 no.4
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• pp.236-241
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• 2011

Polysilazane and silazane-based precursor films were deposited on stacked TiN/Ti/TEOS/Si-substrate by spin-coating, then annealed at $150{\sim}400^{\circ}C$, integrated further to form the top electrode and pad, and finally characterized. The precursor solutions were composed of 20% perhydro-polysilazane ($SiH_2NH$)n, and 20% hydropolymethyl silazane ($SiHCH_3NH$)n in dibutyl ether. Annealing of the precursor films led to the compositional change of the two chemicals into silicon (di)oxides, which was confirmed by Fourier transform infrared spectroscopy (FTIR) spectra. It is thought that the different results that were obtained originated from the fact that the two precursors, despite having the same synthetic route and annealing conditions, had different chemical properties. Electrical measurement indicated that under 0.6MV/cm, a larger capacitance of $2.776{\times}10^{-11}$ F and a lower leakage current of 0.4 pA were obtained from the polysilazane-based dielectric films, as compared to $9.457{\times}10^{-12}$ F and 2.4 pA from the silazane-based film, thus producing a higher dielectric constant of 5.48 compared to 3.96. FTIR indicated that these superior electrical properties are directly correlated to the amount of Si-O bonds and the improved chemical bonding structures of the spin-on dielectric films, which were derived from a precursor without C. The chemical properties of the precursor films affected both the formation and the electrical properties of the spin-on dielectric film.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.197-202
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• 2009

The Luciola lateralis larva took 5.3 days from climbing on the land to the pupal cocoon formation. It took 6.6 days for a larva to eventually transform to a pupa after building a pupal cocoon. The size of pupal cocoon was 10.1 mm in length, 4.7 mm in width and its wall thickness was 1.3 mm. The mean pupal period was 10.5 days. The adult stayed 6.8 days in the pupal cocoon before escaping the cocoon. The peak adult emergence appeared around 9 p.m., and decreased after 10 p.m. The optimal soil temperature for emergence was $23.4^{\circ}C$. The female adult of the natural population (Nat-type) lived shorter, laid fewer eggs, and the oviposition frequency was fewer than that of the Lab-type individuals. However, a few individuals from the natural population laid 200-400 eggs. The less number of oviposition in the natural population may be due to the fact that the female adults might lay eggs before the collection for the experiment.

• Microbiology and Biotechnology Letters
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• v.51 no.2
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• pp.157-166
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• 2023

Three lactic acid bacteria (LAB) producing exopolysaccharides (EPSs) were isolated from Pa (green onion)-kimchi, and identified as Weissella confusa (SKP 173), Weissella cibaria (SKP 182), and Leuconostoc citreum (SKP 281), respectively by 16S rRNA gene sequencing. The yields of EPS were 21.27, 18.53, and 15.4 g/l for EPS from SKP 173, 182, and 281, respectively when grown in MRS broth containing sucrose (5%, w/v). Total sugar contents were 64.39, 62.84, and 65.16% (w/w) for EPS from SKP 173, 182, and 281, respectively while the protein contents were 0.33, 0.31, and 0.25% (w/w), respectively. EPSs from W. confusa SKP 173 and W. cibaria SKP 182 contained glucose only but EPS from L. citreum SKP 281 contained glucose and glucitol. Viscosities of the 2% (w/w) freeze-dried EPS solution were 9.60, 8.00, and 8.20 centipoise (cP) for EPS from SKP 173, 182, and 281, respectively. Viscosities of culture grown in MRS broth with 5% sucrose (no glucose) were 92.98, 57.19, and 18.8 cP, respectively. The average molecular weights of EPSs were larger than 2 × 10⁷ Da. Fourier transform infrared spectroscopy (FT-IR) analyses of EPSs showed typical carbohydrate peaks, suggesting that the EPSs consisted of pyranose saccharides with α-(1,6) and α-(1,3) glycosidic linkages. L. citreim SKP 281 was used as the starter for yogurt fermentation, and EPS production was confirmed.

• Communications of Mathematical Education
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• v.25 no.2
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• pp.381-402
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• 2011

In this paper we study formulae of the triangle's area. We solve problems related with making new formulae of the triangle's area. These formulae is consisted of some elements of triangle, for example side, angle, median, perimeter, radius of circumcircle. We transform formulae $S=\frac{1}{2}acsinB$, $S=\frac{abc}{4R}$, $S=\sqrt{p(p-a)(p-b)(p-c)}$, and make new formulae of the triangle's area. Some formulas are received in the process of Research and Education program in the science high school. We expect that our results will be used in the Research and Education program in the science high school.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.8
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• pp.1186-1194
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• 2019

Objective: The influence of broiler carcass scalding conditions on chicken breast meat quality parameters was investigated. Methods: Two hundred and seventy Cobb broiler chickens from 42 to 48 days old were slaughtered according to the standard industry practice and scalded in five temperature/time combinations-$T_1$, $54^{\circ}C/210s$; $T_2$, $55^{\circ}C/180s$; $T_3$, $56^{\circ}C/150s$; $T_4$, $57^{\circ}C/120s$; $T_5$, $58^{\circ}C/90s$. Results: Scalding temperature increase resulted in higher values of external and ventral lightness and in protein functionality reduction-determined by emulsification capacity and protein denaturation-in chicken breast fillets 24 h post-mortem. Protein secondary structures had conformational changes, with a decrease of the ${\alpha}$-helix and an increase of the ${\beta}$-sheet and ${\beta}$-turn proportions, mainly in $T_1$ and $T_5$ samples, determined by Fourier-transform infrared spectroscopy in an attenuated reflectance mode analysis. The chemical composition, pH, water holding capacity and Warner-Bratzler shear force did not differ among the treatments. In the fatty acid profile, the 18:1n-9 was lower in $T_5$, which suggested that the high scalding-temperature could have caused the lipid oxidation. The values of the polyunsaturated fatty acids (PUFA), such as 22:2, 20:4n-6, and 22:6n-3, were highest in the $T_5$, thus being related to the phospholipid cellular membrane collapse in this experimental condition and subsequent release of these PUFA. Conclusion: Intermediate scalding-parameters avoided the negative changes in the chicken meat quality.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1513-1520
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• 2013

Novel chitosan (CS) based membrane networks were developed by solution casting and followed by crosslinking with different crosslinkers such as glutaraldehyde, urea-formaldehyde, and thiourea-formaldehyde. The developed membrane networks were designated as CS-GA, CS-UF and CS-TF. Crosslinking reaction of CS membranes was confirmed by Fourier transform infrared spectroscopy. Membrane rigidity and compactness were studied by the differential scanning calorimetry. The surface morphology of CS membranes was characterized by scanning electron microscopy. The sorption behaviour with respect to contact time, initial pH and initial metal ion concentration were investigated. The maximum adsorption capacity of CS-GA, CS-UF and CS-TF sorbents was found to be 1.03, 1.2 and 1.18 mM/g for $Cu^{2+}$ and 1.48, 1.55 and 2.18 mM/g for $Ni^{2+}$ respectively. Swelling experiments have been performed on the membrane networks at $30^{\circ}C$. Desorption studies were performed in acid media and EDTA and it was found that the membranes are reusable for the metal ion removal for three cycles. The developed membranes could be successfully used for the separation of $Cu^{2+}$ and $Ni^{2+}$ metal ions from aqueous solutions.

• Journal of the Semiconductor & Display Technology
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• v.9 no.2
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• pp.49-54
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• 2010

We have successfully synthesized $CeO_2$ nanopowders by means of the hydrothermal method, in a low temperature range of $100-200^{\circ}C$. In order to investigate the structure and morphology of the nanopowders, scanning electron microscopy and X-ray diffraction have been employed. In addition, for exploring the optical properties, Raman spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy have been used. In the optimized condition, with the pH, velocity, and time of 4.5, 600 rpm, and 60 h, the $CeO_2$ nanopowders with a diameter ranging from 50 to 150 nm have been synthesized. The nanopowders exhibited the visible emission mainly in the blue region. With comparing the reaction time, it is revealed that the extinction of functional groups at 60 h contributed to the growth and homogenization of the $CeO_2$ powders. Since the overgrowth and agglomeration of nanopowders were found, we suggest that the cracking/growth process is more favorable mechanism than the dissolution/precipitation process.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.207-210
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• 2008

In this paper, we researched the dielectric properties and voltage dependence on slice XLPE sheet from 22[kV] and 154[kV] power cable. We studied effects for impurities and water for semiconductor shield through a dielectric properties experiment to estimate performance of insulating materials in power cable. Capacitance and $tan{\delta}$ of 22[kV], 154[kV] were 53/43[pF] and $7.4{\times}10^{-4}$, $2.1510^{-4}$. In these results, the trend was increased with the increase of temperature. The tan6 of XLPE/semiconductor layer was increased as compared with that of XLPE. Dielectric properties reliability of tan6 was small. Also, To improve mean-life and reliability of power cable in this study, we have investigated chemical properties showing by changing the content of carbon black that is semiconductive additives for underground power transmission. Specimens were made of sheet form with the three of existing resins and the nine of specimens for measurement. Chemical properties of specimens was measured by FT-ATR (Fourier Transform Attenuated Total Reflectance). The condition of specimens was a solid sheet. We could observe functional group (C=O, carbonyl group) of specimens through FT-ATR. From these experimental result, the concentration of functional group (C=O) was high according to increasing the content of carbon black. We could know EEA was excellent more than other specimens from above experimental results.