• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.711-717
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• 2011

Two dimensional simulation results of a capacitively coupled oxygen plasma in a cylindrical reactor geometry are presented. Detailed electron impact reaction rates, which strongly depend on electron energy, are computed from collision cross sections of electrons with $O_2$ and O. Through the coupling of a three moment plasma model with a neutral chemistry/transport model are predicted spatiotemporal distributions of both charged species (electron, $O_2{^+}$, $O^+$, $O_2{^-}$, and $O^-$) and neutral species including ground states ($O_2$ and O) and metastables, known to play important roles in oxygen plasma, such as $O_2(a^1{\Delta}_g)$, $O_2(b^1{{\Sigma}_g}^+)$, $O(^1D)$, and $O(^1S)$. The simulation results clearly verify the existence of a double layer near sheath boundaries in the electronegative plasma.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1265-1272
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• 2007

A solid acid catalyst, NiSO4/CeO2-ZrO2 was prepared simply by promoting ZrO2 with CeO2 and supporting nickel sulfate on CeO2-ZrO2. The support of NiSO4 on ZrO2 shifted the phase transition of ZrO2 from amorphous to tetragonal to higher temperatures because of the interaction between NiSO4 and ZrO2. The surface area of 10-NiSO4/1-CeO2-ZrO2 promoted with CeO2 and calcined at 600 oC was very high (83 m2/g) compared to that of unpromoted 10-NiSO4/ZrO2 (45 m2/g). This high surface area of 10-NiSO4/1-CeO2-ZrO2 was due to the promoting effect of CeO2 which makes zirconia a stable tetragonal phase as confirmed by XRD. The role of CeO2 was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity of the sample, and high thermal stability of the surface sulfate species. 10-NiSO4/1- CeO2-ZrO2 containing 1 mol% CeO2 and 10 wt% NiSO4, and calcined at 600 oC exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.57-61
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• 2004

Zinc Oxide (ZnO) have the crystal structure of wurtzite which is semiconducting oxide with band gap energy of 3.3eV. $In_2O_3$-doped ZnO films were fabricated by electron beam evaporation at $400^{\circ}C$ and their characteristics were investigated. The content of $In_2O_3$ in ZnO films had a marked effect on the electrical properties of the films. As $In_2O_3$ content decreased. $In_2O_3$-doped ZnO films was converted amorphous into crystallized films and showed a better characteristics generally as a transparent conducting oxide. As $In_2O_3$-doped ZnO films were prepared by $In_2O_3$-doped ZnO pellet with 0.2at% of $In_2O_3$ content, the value of resistivity was about $6.0 {\times} 10^{-3} {\Omega}cm$. The transmittance was higher than 85% throughout the visible range.

• Korean Journal of Materials Research
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• v.29 no.8
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• pp.463-468
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• 2019

The electrical and interfacial properties of $HfO_2/Al_2O_3$ and $Al_2O_3/HfO_2$ dielectrics on AlN/p-Ge interface prepared by thermal atomic layer deposition are investigated by capacitance-voltage(C-V) and current-voltage(I-V) measurements. In the C-V measurements, humps related to mid-gap states are observed when the ac frequency is below 100 kHz, revealing lower mid-gap states for the $HfO_2/Al_2O_3$ sample. Higher frequency dispersion in the inversion region is observed for the $Al_2O_3/HfO_2$ sample, indicating the presence of slow interface states A higher interface trap density calculated from the high-low frequency method is observed for the $Al_2O_3/HfO_2$ sample. The parallel conductance method, applied to the accumulation region, shows border traps at 0.3~0.32 eV for the $Al_2O_3/HfO_2$ sample, which are not observed for the $Al_2O_3/HfO_2$ sample. I-V measurements show a reduction of leakage current of about three orders of magnitude for the $HfO_2/Al_2O_3$ sample. Using the Fowler-Nordheim emission, the barrier height is calculated and found to be about 1.08 eV for the $HfO_2/Al_2O_3$ sample. Based on these results, it is suggested that $HfO_2/Al_2O_3$ is a better dielectric stack than $Al_2O_3/HfO_2$ on AlN/p-Ge interface.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.93-100
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• 1992

Sinterability, mechanical and electrical properties of yttria-stabilized zirconia(92 mole% $ZrO_{2}$+8 mole% $Y_{2}O_{3}$) doped with 0.5 mole% $SiO_{2}$ and $0{\sim}2.0 mole%{\;}Al_{2}O_{3}$ were studied as a function of $Al_{2}O_{3}$ addition. Sintered density increased with increasing $Al_{2}O_{3}$ addition up to 0.5 mole % but leveled off with further addition. Victors hardness is proportional to sintered density. The specimen with 0.5 mole% $Al_{2}O_{3}$ and 0.5 mole% $SiO_{2}$ exhibited the maximum electrical conductivity and revealed a maximum electromotive force for a given oxygen partial pressure. Experimental voltage curve of this oxygen sensor take on a sharper, more steplike transition at the stoichiometric A/F ratio than those of other commercial oxygen sensors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.402-410
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• 2000

The electrical properties and stability of Pr$_{6}$/O$_{11}$-based ZnO wvaristors consisting of ZnO-Pr$_{6}$/O$_{11}$-CoO-Dy$_{2}$/O$_{3}$ based ceramics were investigated in the Dy$_{2}$/O$_{3}$ additive content range o 0.0 to 2.0 mol%. The density was nearly constant 5.62 g/cm$^3$corresponding to 97% of theoretical density as Dy$_{2}$/O$_{3}$ additive content increases up to 0.5 mol%. However the density decreased as Dy$_{2}$/O sub 3/ additive content is further additive content. Pr$_{6}$/O$_{11}$-based ZnO varistors doped with 0.5mol% Dy$_{2}$/O$_{3}$ exhibited a good nonlinearity, which is 37.76 in the nonlinear exponent and 5.36 $mutextrm{A}$ in the leakage current. And they exhibited very stress (0.80 V$_{1mA}$/9$0^{\circ}C$/12h)+(0.85 V$_{1mA}$/115$^{\circ}C$/12h)+(0.95 V$_{1mA}$/1$25^{\circ}C$/12h). Consequently it was estimated that ZnO-0.5 mol% Pr$_{6}$/O$_{11}$-1.0 mol% CoO-0.5 mol% Dy$_{2}$/O$_{3}$ based ceramics will be sufficiently used as a basic composition to develop the advanced Pr$_{6}$/O$_{11}$-based ZnO varistors in the future.he future.uture.he future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.335-338
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• 1999

The effect of monoclinic $ZrO_2$(pure) and tetragonal $ZrO_2$ containing 5.35wt% $Y_2$$O_3$(Y-TZP) addition on the mechanical properties and thermal shock resistance of $Al_2$$O_3$ ceramic were investigated. The addition of $ZrO_2$(m) and Y-TZP increased sintering density of $Al_2$$O_3$. The vickers hardness increased with increasing the volume fraction of Y-TZP going through a maximum at 20wt%. The hardness of the specimens was found to be depend on the sintering density. With increasing the volume fraction of $ZrO_2$(m) and Y-TZP, the fracture toughness of the composite is increased. This result may be taken as evidence that toughening of ${Al_2}{O_3}$ can also be achieved by the transformation toughening and microcrack toughening of $ZrO_2$. The property of the& shock for ${Al_2}{O_3}$-$ZrO_2$ composites was improved by increasing the volume fraction of monoclinic $ZrO_2$(pure).Grain size increased with increasing the volume fraction of $ZrO_2$.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.988-992
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• 2011

$CO_2$ adsorption on mineral sorbents has a potential to sequester $CO_2$. This study used a density functional theory (DFT) study of $CO_2$ adsorption on barium oxide (BaO) in the presence of $H_2O$ to determine the role of $H_2O$ on the $CO_2$ adsorption properties on the ($2{\times}2$; $11.05\;{\AA}{\times}11.05\;{\AA}$) BaO (100) surface because BaO shows a high reactivity for $CO_2$ adsorption and the gas mixture of power plants generally contains $CO_2$ and $H_2O$. We investigated the adsorption properties (e.g., adsorption energies and geometries) of a single $CO_2$ molecule, a single $H_2O$ molecule on the surface to achieve molecular structures and molecular reaction mechanisms. In order to evaluate the coordinative effect of $H_2O$ molecules, this study also carried out the adsorption of a pair of $H_2O$ molecules, which was strongly bounded to neighboring (-1.91 eV) oxygen sites and distant sites (-1.86 eV), and two molecules ($CO_2$ and $H_2O$), which were also firmly bounded to neighboring sites (-2.32 eV) and distant sites (-2.23 eV). The quantum mechanical calculations show that $H_2O$ molecule does not influence on the chemisorption of $CO_2$ on the BaO surface, producing a stable carbonate due to the strong interaction between the $CO_2$ molecule and the BaO surface, resulting from the high charge transfer (-0.76 e).

• Fashion & Textile Research Journal
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• v.20 no.6
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• pp.645-655
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• 2018

Online to Offline(O2O), a new model of e-commerce, has been gradually recognized and accepted by consumers. Electronic commerce has become diversified and O2O marketing is the new trend of e-commerce. The rapid popularization of mobile Internet and online shopping makes O2O service gets more attention. Although recently O2O service and O2O marketing get much attention, there is no much preceding research about the antecedents of mobile shopping of O2O market. The purpose of the study is to examine the effect of shopping orientation on intention to reuse O2O services and the moderating effect of impulse buying tendency. A total of 209 surveys were collected online in total for the data of the study. The key findings of this study are as follows: First, convenience seeking shopping orientation has a positive effect on the intention to reuse O2O service and brand seeking shopping orientation has, too. Second, impulse buying tendency positively moderated the relationship between hedonic seeking shopping orientation and intention to reuse O2O service, and negatively moderated sales seeking shopping orientation and intention to reuse O2O service. The results of this study presented some implications for operators at O2O service area. Research findings and study limitations are discussed.

• Journal of the Korean Ceramic Society
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• v.27 no.4
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• pp.567-573
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• 1990

Solidification condition for preparing transparent ${\gamma}$-6Bi2O3.GeO2 polycrystals by unidirectional solidification of melt, were investigaetd and the properties of the polycrystals prepared were measured. The ${\gamma}$-6Bi2O3.GeO2 polycrystals showing transparency like a single crystal were obtained by the unidirectional solidification of ${\gamma}$-6Bi2O3.GeO2 melt at a solidification rate of 0.5mm/h under a thermal gradient of 12$0^{\circ}C$/cm. The transparent polycrystals obtained showed the same photoconduction and optical activity as the ${\gamma}$-6Bi2O3.GeO2 single crystals grown by Czochralski method. But the electro-optic effect of polycrystals was heterogeneous because the colummar ${\gamma}$-6Bi2O3.GeO2 crystals were not oriented to the particular crystallographic direction.