• Journal of the Korean Ceramic Society
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• v.54 no.4
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• pp.303-307
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• 2017

Pure $In_2O_3$, 0.5 and 1.0 wt% Mg doped $In_2O_3$ hollow spheres were synthesized by ultrasonic spray pyrolysis of a solution containing In-, Mg-nitrate and sucrose and their gas sensing characteristics to 5 ppm $C_2H_5OH$, p-xylene, toluene, and HCHO were measured at 250, 300 and $350^{\circ}C$. Although the addition of Mg decreases the specific surface area and the volume of meso-pores, the gas response (resistance ratio) of the 0.5 wt% Mg doped $In_2O_3$ hollow spheres to 5 ppm $C_2H_5OH$ at $350^{\circ}C$ (69.4) was significantly higher than that of the pure $In_2O_3$ hollow spheres (24.4). In addition, the Mg doped $In_2O_3$ hollow spheres showed the highest selectivity to $C_2H_5OH$. This was attributed to the dehydrogenation of $C_2H_5OH$ assisted by basic MgO into reactive $CH_3CHO$ and $H_2$.

• Journal of the Mineralogical Society of Korea
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• v.15 no.1
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• pp.78-84
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• 2002

New pyrochlore-type phases($A_2$$B_2$$O_{7}$) were synthesized in the systems: CaO-C$eO_2$-T$iO_2$, CaO-$UO_2$(T$hO_2$)-Z$rO_2$, CaO-$UO_2$(T$hO_2$)-$Gd_2$$O_3$-T$iO_2$-Z$rO_2$, 및 CaO-T$hO_2$-S$nO_2$. The starting materials were pressed with the pressure of 200~400 MPa and sintered at 1500~ 155$0^{\circ}C$ for 4~8 hours in air and at 1300~ 135$0^{\circ}C$ for 5 ~50 hours under oxygen atmosphere. The products were characterized using XRD, SEM/EDS and TEM. In the bulk compositions of CaCe$Ti_2$$O_{7}$, CaTh$Zr_2$$O_{7}$,($Ca_{0.5}$ Gd$Th_{0.5}$)(ZrTi)$O_{7}$) ($Ca_{0.5}$Gd$Th_{0.5}$)(ZrTi)$O_{7}$, ($Ca_{0.5}$G$dU_{0.5}$)(ZrTi)$O_{7}$ and CaTh$Sn_2$$O_{7}$ , pyrochlore was the major phase, together with other oxide phase $of_2$$O_{7}$ fluorite structure. In the samples with target compositions CaU$Zr_2$$O_2$및 $Ca_{0.5}$ G$dU_{0.5}$)$Zr_2$T$iO_{7}$ pyrochlore was not identified, but a fluorite-structured phase was detected. The formation factor as the stable phase depended on crystal chemical characteristics of the actinide and lanthanide elements of the system concerned.

• Journal of The Korean Astronomical Society
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• v.48 no.6
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• pp.357-364
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• 2015

We observe ten known 22GHz H₂O maser galaxies during February 19-22, 2011 using the 21 m Tamna telescope of the Korean VLBI Network and a new wide-band digital spectrometer. Simultaneously we searched for 43GHz SiO v = 1, 2, J = 1-0 maser emission. We detect H₂O maser emission towards five sources (M 33, NGC 1052, NGC 1068, NGC 4258, M 82), with non-detections towards the remaining sources (UGC 3193, UGC 3789, Antennae H₂O-West, M 51, NGC 6323) likely due to sensitivity. Our 22GHz spectra are consistent with earlier findings. Our simultaneous 43GHz SiO maser search produced non-detections, yielding - for the first time - upper limits on the 43GHz SiO maser emission in these sources at a 3 σ sensitivity level of 0.018K-0.033K (0.24 Jy-0.44 Jy) in a 1.75 km s⁻¹ velocity resolution. Our findings suggest that any 43GHz SiO masers in these sources (some having starburst-associated H₂O kilomasers) must be faint compared to the 22GHz H₂O maser emission.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.196-196
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• 2011

Molecular $N_2O$ has bee known to react over oxygen vacancy on a reduced rutile $TiO_2$(110)-1${\times}$1 surface to desorb as molecular $N_2$ leaving oxygen atom behind. In the present study, we investigated the reaction of $N_2O$ on rutile $TiO_2$(110) using temperature-programmed desorption (TPD). Our results indicate that $N_2O$ does not react over the oxygen vacancy under a typical UHV experimental condition. On a rutile $TiO_2$(110)-1${\times}$1 with a well-defined oxygen vacancy concentration of 5% ($2.6{\times}10^{13}/cm^2$), $N_2O$ desorption features show a monolayer peak maximum at 135 K followed by a small peak maximum at 170 K. When the oxygen vacancy is blocked with $H_2O$, the $N_2O$ peak at 170 K disappears completely, indicating that the peak is due to molecular $N_2O$ interacting with oxygen vacancy. The integrated amount of desorbed $N_2O$ plotted against the amount of adsorbed $N_2O$ however shows a straight line with no offset indicating no loss of $N_2O$ during our cycles of TPD measurements. In addition, our $N_2O$ uptake measurements at 70~100 K showed no $N_2$ (as a reaction product) desorption except contaminant $N_2$. Also, $H_2O$ TPD taken after $N_2O$ scattering up to 350 K indicates no change in the vacancy-related $H_2O$ desorption peak at 500 K showing no change in the oxygen vacancy concentration after the interaction with $N_2O$.

• The Plant Pathology Journal
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• v.35 no.4
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• pp.287-300
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• 2019

Spot blotch caused by Bipolaris sorokiniana has spread to more than 9 million ha of wheat in the warm, humid areas of the Eastern Gangetic Plains (EGP) of South Asia and is a disease of major concern in other similar wheat growing regions worldwide. Differential lignin content in resistant and susceptible genotypes and its association with free radicals such as hydrogen peroxide ($H_2O_2$), superoxide ($O_2{^-}$) and hydroxyl radical ($OH^-$) were studied after inoculation under field conditions for two consecutive years. $H_2O_2$ significantly influenced lignin content in flag leaves, whereas there was a negative correlation among lignin and $H_2O_2$ to the Area Under Disease Progress Curve (AUDPC). The production of $H_2O_2$ was higher in the resistant genotypes than susceptible ones. The $O_2{^-}$ and $OH^-$ positively correlated with AUDPC but negatively with lignin content. This study illustrates that $H_2O_2$ has a vital role in prompting lignification and thereby resistance to spot blotch in wheat. We used cluster analysis to separate the resistant and susceptible genotypes by phenotypic and biochemical traits. $H_2O_2$ associated lignin production significantly reduced the number of appressoria and penetration pegs. We visualized the effect of lignin in disease resistance using differential histochemical staining of tissue from resistant and susceptible genotypes, which shows the variable accumulation of hydrogen peroxide and lignin around penetration sites.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.137-138
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• 2011

구리 이온은 -0.40V (vs. SCE)에서 전기화학적 환원이 일어나는 반면, 니켈 이온은 -1.19V (vs. SCE)에서 전착이 발생한다. 따라서, 단일 도금욕조 내에서 Ni-Cu 합금도금층을 제조하기 위해서는 두 금속 이온종 간의 전위차를 줄여주어야 하는데, 이를 위해 본 연구에서는 $Na_3C_6H_5O_7{\cdot}2H_2O$를 착화제로 사용하였다. 다양한 Ni-Cu 합금 도금층의 조성을 얻기 위하여 기본 도금욕 내 황산니켈과 황산구리의 비율을 10:1로 설정하였다. 도금 공정 조건에 따른 합금 도금층 조성 변화를 관찰하기 위하여 도금액 pH와 교반 속도에 따른 도금층 조성 변화를 분석하였으며, 도금액의 UV-VIS과 도금층의 XRD 와 SEM 측정을 통하여 도금욕과 도금층 간의 상관 관계를 유추하였다. 본 도금액에 사용된 $Na_3C_6H_5O_7{\cdot}2H_2O$ 착화제의 효과는 pH3에서 가장 현저하였으며, pH 변화 및 교반 속도 변화를 이용하여 다양한 합금 조성을 얻을 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.60.2-60.2
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• 2010

A $TiO_2$ films in dye-sensitized solar cells was fabricated using $TiO_2$ colloidal sol prepared from titanium iso-propoxide used as a starting material by applying the sol-gel method. It was characterized by particle size analyzer, XRD, FE-SEM, and BET analysis. The adsorption isotherms of dye molecule on $TiO_2$ films were obtained at three different temperatures (30, 45, $60^{\circ}C$) and at three different pH (3, 5, 7). The adsorption kinetics of dye molecule on $TiO_2$ films were obtained at three different temperatures (30, 45, $60^{\circ}C$. The adsorption experimental data were correlated with Langmuir isotherm model and pseudo-second-order model. Also the isosteric enthalpies of dye adsorption were calculated by the Clausius-Clapeyron equation. In addition, the adsorption energy distribution functions which describe heterogeneous characteristics of nanocrystalline $TiO_2$ film surface were calculated by using the generalized nonlinear regularization method. We found that efficient adsorption of N719 dye from aqueous solution onto $TiO_2$ films can be successfully achieved by dye adsorption conditions and morphology of $TiO_2$ films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.228-231
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• 1996

We prepared $LiCo_{1-x}Ni_{x}O_2$ by reacting stoichiometric mixture of LiOH.$H_2O$, $CoCO_3$.$xH_2O$ and $Ni(OH)_2$ (mole ratio respectively) and heating at $850^{\circ}C$ for 5h. We awared through XRD that from 0 to 0.5 at x in $LiCo_{1-x}Ni_{x}O_2$ is well formed for hexagonal structure, but the more $LiCo_{1-x}Ni_{x}O_2$ involve NI, the more hexagonal structure is not well formed. In the result of charge/discharge test, charge/discharge characteristic of $LiCo_{1-x}Ni_{x}O_2$ is similar to that of $LiCoO_2$. Therefore, $LiCo_{1-x}Ni_{x}O_2$ is superior to $LiCoO_2$ for Li secondary battery

• Journal of Magnetics
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• v.21 no.1
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• pp.46-50
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• 2016

$Fe_2O_3/TiO_2$ nanocomposite were successfully synthesized by co-precipitation method using $Fe(NO_3)_3{\cdot}9H_2O$ and $Ti(SO_4)_2$ as raw materials. Structural and textural features of the mixed oxide samples were characterized by X-ray diffractometer, field emission scanning electron microscopy and energy-dispersive X-ray. The effects of initial concentration of oxytetracycline (OTC), different competitive ions and organics on the photocatalytic degradation rate of OTC by the $Fe_2O_3/TiO_2$ nanocomposite were analyzed under UV and visible light irradiation. The results indicate that the optimized initial concentration of OTC was 50 mg/L to achieve the best photocatalytic efficiency. $Cu^{2+}$, $NH_4{^+}$, $C_3H_8O$ and EDTA in the aqueous suspension were found to suppress the degradation rate of OTC, whereas the effect of $NO_3{^-}$ and $H_2C_2O_4$ can be ignored.

• Korean Journal of Materials Research
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• v.26 no.9
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• pp.468-471
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• 2016

$SnO_2:CNT$ thick films for gas sensors were fabricated by screen printing method on alumina substrates and were annealed at $300^{\circ}C$ in air. The nano $SnO_2$ powders were prepared by solution reduction method using tin chloride ($SnCl_2.2H_2O$), hydrazine ($N_2H_4$) and NaOH. Nano $SnO_2:CNT$ sensing materials were prepared by ball-milling for 24h. The weight range of CNT addition on the $SnO_2$ surface was from 0 to 10 %. The structural and morphological properties of these sensing material were investigated using X-ray diffraction and scanning electron microscopy and transmission electron microscope. The structural properties of the $SnO_2:CNT$ sensing materials showed a tetragonal phase with (110), (101), and (211) dominant orientations. No XRD peaks corresponding to CNT were observed in the $SnO_2:CNT$ powders. The particle size of the $SnO_2:CNT$ sensing materials was about 5~10 nm. The sensing characteristics of the $SnO_2:CNT$ thick films for 5 ppm $H_2S$ gas were investigated by comparing the electrical resistance in air with that in the target gases of each sensor in a test box. The results showed that the maximum sensitivity of the $SnO_2:CNT$ gas sensors at room temperature was observed when the CNT concentration was 8wt%.