• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.276-279
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• 2000

Ferroelectric properties of $SrBi_2TaNbO_9$ (SBTN) thin films were changed by the amount of Bi content in SBTN. We suggested that the addition of excess Bi into the films could be accomplished by heat-treating $SBTN/Bi_2O_3/SBTN$ heterostructure fabricated by r.f. magnetron sputtering method. Excess Bi composition was controlled by the thickness of the sandwiched $Bi_2O_3$ from 0 to $400\;\AA$. When the SBTN thin films were inserted by $400\;{\AA}\;Bi_2O_3$ layer, $Bi_2Pt$ phase was formed as a second phase in SBTN films, resulting in poor ferroelectric properties. The onset temperature for hysteresis loop can be reduced by heat treating $SBTN/Bi_2O_3/SBTN$ heterostructure. The films with $SBTN/Bi_2O_3(100\;{\AA})/SBTN$ hetero-structure followed by annealing at $650^{\circ}C$ for 30 min show 2Pr and Ec of $5.66\;{\mu}C/\textrm{cm}^2$ and 54 kV/cm, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.54-58
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• 1996

In this paper, the structure, dieletric and piezoelectric properties of Pb(Fe$_{\frac{1}{2}}$/Sb$_{\frac{1}{2}}$$O_3$+ Pb(Zr$_{0.52}$ Ti$_{0.48}$ )O$_3$system ceramics were investigated and the effects of donor Nb$^{+5}$ on these properties were characterized for the application of the actuator. In xPb(Fe$_{\frac{1}{2}}$Sb$_{\frac{1}{2}}$)O$_3$+ (1-x) Pb(Zr$_{0.52}$ Ti$_{0.48}$ )O$_3$system ceramics, tetragonality decreased as x and Nb$_2$O$_{5}$ wt% were increased. In 0.05Pb(Fe$_{\frac{1}{2}}$Sb$_{\frac{1}{2}$}$)O$_3$+ 0.95 Pb(Zr$_{0.52}$ Ti$_{0.48}$ )O$_3$system, grain size was smallest but showed best dielectric and piezoelectric properties. The specimen sintered at 120$0^{\circ}C$ in 0.05pb(Fe$_{\frac{1}{2}}$Sb$_{\frac{1}{2}}$ )O$_3$+ 0.95 Pb(Zr$_{0.52}$ Ti$_{0.48}$ )O$_3$+ Nb$_2$O$_{5}$ 0.6wt% exihibited best piezoeletric properties such as $K^{p}$ =64%, d$_{33}$ =490 [$\times$10$^{-12}$ C/N] and strain was 1320[$\times$10$^{-6}$ Δ$\ell$/$\ell$]at AC 6kV/cm

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2603-2607
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• 2009

$LiNi_{0.5-x}Co_{2x}Mn_{0.5-x}O_{2}$ (x = 0, 0.1, 1/6, 1.2, 0.3) were synthesized by the solid-state reaction method. The crystal structure was analyzed by X-ray powder diffraction and Rietveld refinement. $LiNi_{0.5-x}Co_{2x}Mn_{0.5-x}O_{2}$ samples give single phases of hexagonal layered structures with a space group of R-3m for x = 0.1, 1/6, 0.2, and 0.3. The lattice constants of a and c-axis were decreased with the increase in Co contents in samples. The thickness of MO2 slab was decreased and inter-slab distance was increased with the increase in Co contents in $LiNi_{0.5-x}Co_{2x}Mn_{0.5-x}O_{2}$. According to XPS analysis, the valence states of Mn, Co, and Ni in the sample are mainly +4, +3, and +3, respectively. The discharge capacity of 202 mAh/g at 0.1C-rate in the potential range of 4.7 - 3.0 V was obtained in $LiNi_{0.3}Co_{0.4}Mn_{0.3}O_2$ sample, and $LiNi_{0.4}Co_{0.2}Mn_{0.4}O_2$ gives excellent cycle performance in the same potential range.

• Journal of Life Science
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• v.24 no.12
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• pp.1291-1300
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• 2014

Peroxiredoxins (Prxs) are a ubiquitous family of antioxidant enzymes that participate in a variety of biological processes, including $H_2O_2$-mediated signal transduction, molecular chaperoning, and mitochondrial function. In this study, we isolated and characterized a Prx 2 cDNA from abalone (Haliotis discus hannai). The abalone Prx 2 cDNA encoded a 199-amino acid polypeptide that belongs to a class of typical 2-Cys Prxs that contain peroxidatic and resolving cysteines. The deduced abalone Prx 2 protein showed strong homology (64-99%) with Prx 2 proteins from other species, including mollusk, fish, amphibians, and mammals, and it was most closely related to disk abalone (H. discus discus) Prx 2. Abalone Prx 2 mRNA was ubiquitously detected in tested tissues, and its expression was comparatively high in the mantle, gills, liver, foot, and digestive duct. The expression level of abalone Prx 2 mRNA was 106.7-fold, 51.9-fold, and 437.8-fold higher, respectively, in the gills, digestive duct, and liver than in the muscles. The expression level of abalone Prx 2 mRNA in the liver peaked at 6 hr postinfection with Vibrio parahemolyticus and decreased at 12 hr postinfection. The expression level of abalone Prx 2 mRNA in hemocytes was drastically increased at 1 hr postinfection with V. parahemolyticus. These results suggest that abalone Prx 2 is conserved through evolution and that it may play a role similar to that of its mammalian counterpart.

• Journal of the Korean Chemical Society
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• v.38 no.1
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• pp.55-60
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• 1994

Molecular orbital calculations at the extended Huckel level have been carried out for $Cp_2TiSiHPh(1),\;[Cp_2Ti]_2[{\mu}-HSi(HPh)][{\mu}-H] (2),\;and\;[Cp_2TiSiH_2Ph]_2$ (3) complexes which are important intermediates in organosilane polymerization. Stable geometry of complex 1 is not $C_{2V}$, but Cs symmetry and the rotational energy barrier of $SiH_2$ unit is computed to be 14 kcal/mol. The orbital interaction diagrams are studied to characterize the chemical bonding for the electron deficient systems, 2 and 3. It is possible for Si-H to be coordinated to the Ti metal using $\sigma$ bonding.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.1
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• pp.40-46
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• 2013

The isotope ratios of $^{13}C/^{12}C$ and $^{18}O/^{16}O$ for a sample in a mass spectrometer are measured relative to those of a pure $CO_2$ reference gas (i.e., laboratory working standard). Thus, the calibration of a laboratory working standard gas to the international isotope scales (Pee Dee Belemnite (PDB) for ${\delta}^{13}C$ and Vienna Standard Mean Ocean Water (V-SMOW) for ${\delta}^{18}O$) is essential for comparisons between data sets obtained by other groups on other mass spectrometers. However, one often finds difficulties in getting well-calibrated standard gases, because of their production time and high price. Additional difficulty is that fractionation processes can occur inside the gas cylinder most likely due to pressure drop in long-term use. Therefore, studies on laboratory production of pure $CO_2$ isotope standard gas from stable solid calcium carbonate standard materials, have been performed. For this study, we propose a method to extract pure $CO_2$ gas without isotope fractionation from a solid calcium carbonate material. The method is similar to that suggested by Coplen et al., (1983), but is better optimized particularly to make a large amount of pure $CO_2$ gas from calcium carbonate material. The $CaCO_3$ releases $CO_2$ in reaction with 100% pure phosphoric acid at $25^{\circ}C$ in a custom designed, evacuated reaction vessel. Here we introduce optimal procedure, reaction conditions, and samples/reactants size for calcium carbonate-phosphoric acid reaction and also provide the details for extracting, purifying and collecting $CO_2$ gas out of the reaction vessel. The measurements for ${\delta}^{18}O$ and ${\delta}^{13}C$ of $CO_2$ were performed at Seoul National University using a stable isotope ratio mass spectrometer (VG Isotech, SIRA Series II) operated in dual-inlet mode. The entire analysis precisions for ${\delta}^{18}O$ and ${\delta}^{13}C$ were evaluated based on the standard deviations of multiple measurements on 15 separate samples of purified $CO_2$. The pure $CO_2$ samples were taken from 100-mg aliquots of a solid calcium carbonate (Solenhofen-ori $CaCO_3$) during 8-day experimental period. The multiple measurements yielded the $1{\sigma}$ precisions of ${\pm}0.01$‰ for ${\delta}^{13}C$ and ${\pm}0.05$‰ for ${\delta}^{18}O$, comparable to the internal instrumental precisions of SIRA. Therefore, we conclude the method proposed in this study can serve as a way to produce an accurate secondary and/or laboratory $CO_2$ standard gas. We hope this study helps resolve difficulties in placing a laboratory working standard onto the international isotope scales and does make accurate comparisons with other data sets from other groups.

• The Korean Journal of Air & Space Law and Policy
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• v.35 no.2
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• pp.3-40
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• 2020

The term "accident" in the Warsaw Convention of 1929 and the Montreal Convention of 1999, which govern carrier liability in international air transport, is an important criterion for determining carrier liability. However, because there is no explicit definition of the term in the treaty provisions, the term is largely subjected to the judgment and interpretation of the courts. Although there have been numerous changes in purpose and circumstance in the transition from the Warsaw regime to the conclusion of the Montreal Convention, there was no discussion on the concept of "accident" therefore, even after the adoption of the Montreal Convention, there is no doubt that the term is to be interpreted in the same manner as before. On this point, the United States Supreme Court's Air France v. Saks clarified the concept of "accident" and is still cited as an important precedent. Recently, the CJEU, in GN v. ZU, presented a new concept of "accident" introduced in the Montreal Convention: that "reference must be made to the ordinary meaning" in interpreting "accident" and that the term "covers all situations occurring on aboard an aircraft." Furthermore, the CJEU ruled that the term does not include the applicability of "hazards typically associated with aviation," which was controversial in previous cases. Such an interpretation can be reasonably seen as the court's expansion of the concept of "accident," with a focus on "protecting consumer interests," a core tenet of both the Montreal convention and the European Union Regulations(EC: No 889/2002). The CJEU's independent interpretation of "accident" is a departure from the Warsaw Convention and the Saks case, with their focus on "carrier protection," and instead focuses on the "passenger protection" standard of the Montreal Convention. Consequently, this expands both the court's discretion and the carrier's risk management liability. Such an interpretation by the CJEU can be said to be in line with the purpose of the Montreal Convention in terms of "passenger protection." However, there are problems to be considered in tandem with an expanded interpretation of "accident." First, there may be controversy concerning "balance" in that it focused on "passenger protection" in relation to the "equitable balance of interests" between air carriers and passengers, which is the basic purpose of the agreement. Second, huge losses are expected as many airlines fly to countries within the European Union. Third, there is now a gap in the interpretation of "accident" in Europe and the United States, which raises a question on the "unity of rules," another basic tenet of the Convention. Fourth, this interpretation of "accident" by the CJEU raises questions regarding its scope of application, as it only refers to the "hazards typically associated with aviation" and "situations occurring aboard an aircraft." In this case, the CJEU newly proposed a novel criterion for the interpretation of "accident" under the Montreal Convention. As this presents food for thought on the interpretation of "accident," it is necessary to pay close attention to any changes in court rulings in the future. In addition, it suggests that active measures be taken for passenger safety by recognizing air carriers' unlimited liability and conducting systematic reforms.

• Journal of the Korea Organic Resources Recycling Association
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• v.3 no.2
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• pp.79-89
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• 1995

Changes of microbial activity and physicochemical environment during composting of papermill sludge(PMS) in the pilot plant equipped with an agitated bed reactor were monitored for establishing the efficient composting system. Microbial activity determined as the evolution of $CO_2$ increased for the first 10 days after introduction of PMS to the reactor and decreased thereafter. Population changes of microorganisms in the reactor-PMS were not typical as in windrow system. The ratio of thermophilic bacteria to mesophilic bacteria, however, increased slowly even 23 days after introduction. Temperature of PMS increased rapidly from the first day and reached $62^{\circ}C$ at 7 days after introduction and decreased slowly thereafter. The acidity of PMS was pH 6.8 initially, increased to pH 8.0 after 7 days and decreased to pH 7.4 after 23 days. Redox potential(Eh) of PMS was -320mV at the beginning of composting, but it was increased with time to reach -15mV after 23 days composting. However, Eh of PMS pre-sterilized before measurement was average 50mV, regardless of composting periods indicating the major role of microorganisms during composting process. Water content of PMS was 67% initially and decreased to about 50% after 23 days composting in the reactor. Less than 13 days-old compost inhibited growth of radish in the container mixture with bed soil. Based on statistical analysis of microbial and physicochemical parameters of PMS during composting, an equation was developed for determining compost maturity. A number of experiments using various organic wastes are required before application of the formular to the practical use.

• Archives of Pharmacal Research
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• v.19 no.4
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• pp.326-334
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• 1996

We investigated the optimum conditions for conversion of water-insoluble components of basidiocarps of Ganoderma lucidum to water-soluble components by hydrolyzing with chitinase. We also tried it with Ganoderma luciclum residue remaining after extracting hot water-soluble components of Ganoderma lucidum. After hydrolyzing under optimum conditions (20 ppm chitinase, 2% Ganoderma lucidum or 6% Ganoderma lucidum residue, at pH 3 and at $ 35^{\circ}C$), the contents of total water-soluble components (polysaccharide or protein) were measured, and it was found that the contents of water-soluble components increased to 1.5-2.7 fold. Michaelis constant, $K_m$ and maximum rate, $V_max$ calculated by Lineweaver-Burk plot for hydrolysis of Ganoderma lucidum were 1.75% and 0.02%/min respectively and those for hydrolysis of Ganoderma lucidum residue were 53.15% and 0.53%/min respectively The protein-bound polysaccharide was isolated after hydrolysis and molecular weights were measured by Sepharose CL-4B gel filtration and compared with the molecular weights of polysaccharide before hydrolysis.

• ETRI Journal
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• v.15 no.2
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• pp.11-25
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• 1993

Interface trap densities at gate oxide/silicon substrate ($SiO_2/Si$) interfaces of metal oxide semiconductor field-effect transistors (MOSFETs) were determined from the substrate bias dependence of the subthreshold slope measurement. This method enables the characterization of interface traps residing in the energy level between the midgap and that corresponding to the strong inversion of small size MOSFET. In consequence of the high accuracy of this method, the energy dependence of the interface trap density can be accurately determined. The application of this technique to a MOSFET showed good agreement with the result obtained through the high-frequency/quasi-static capacitance-voltage (C-V) technique for a MOS capacitor. Furthermore, the effective substrate dopant concentration obtained through this technique also showed good agreement with the result obtained through the body effect measurement.