• Bulletin of the Korean Chemical Society
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• v.19 no.9
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• pp.985-993
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• 1998

The second order effective valence shell Hamiltonian ($H^v$), which is based on quasidegencrate many-body perturbation theory, is applied to determining the potential energy surfaces and the dipole moment functions of the various valence states of $NH_2$. The $H^v$ calculated values are found to be in good agreement with those of other ab initio calculations or experiments. It signifies the fact that the $H^v$ is a good ab initio method to describe the energies and properties of various valence states with a same chemical accuracy. Furthermore, it is shown that the lowest (second order for energy and the first order for property) order $H^v$ method is very accurate for small molecules like $NH_2$ and the matrix elements of Hv which are computed only once are all we need to accurately describe all the valence states simultaneously.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.735-743
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• 1993

The electrocatalytic reduction of oxygen is investigated by cyclic voltammetry and chronoamperometry at glassy carbon electrode and carbon microelectrode coated with a variety of cobalt phenylprophyrins in various pH solutions. Oxygen reduction catalyzed by the monomeric porphyrin Co(Ⅱ)-TPP mainly occurs through the 2e$^-$ reduction pathway resulting in the formation of hydrogen peroxide whereas electrocatalytic process carried out 4e$^-$ reduction pathway of oxygen to H$_2$O at the electrodes coated with cofacial bis-cobalt phenylporphyrins in acidic solution. The electrocatalytic reduction of oxygen is irreversible and diffusion controlled. The reduction potentials of oxygen in various pH solutions have a straight line from pH 4 to pH 13, but level off in strong acidic solution. The reduction potentials of oxygen shift to positive potential more 400 mV at the electrode coated with monomer Co-TPP compound than bare glassy carbon electrode while 750 mV at the electrode coated with dimer Co-TPP compound.

• Journal of the Korean Ceramic Society
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• v.19 no.4
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• pp.267-274
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• 1982

The sintering behavior and B-H loop properties of $Li_{0.5O4}$ with the addition of $Nb_2O_5$ and $V_2O_5$ have been investigated by observation of microstructures and measurement of semi-static hysteresis loops. The sintering temperature was lowered by the additions of $Nb_2O_5$ and $V_2O_5$ and the effect of $V_2O_5$ addition was greater than that of $Nb_2O_5$. The abnormal grain growth was observed at about 100$0^{\circ}C$(d:4.6g/㎤) and 85$0^{\circ}C$(d:4.5g/㎤) in the specimens with the addition of $Nb_2O_5$ and $V_2O_5$ respectively. The addition of $Nb_2O_5$ retulted in a large and uniform grain size, and the addition of $V_2O_5$ resulted in a uniform grain size but the final density was lower than that of the pure specimen. The squareness was increased and the coercive force was decreased by the addition of $Nb_2O_5$, and the squareness was decreased and the coercive force was increased by the addition of $V_2O_5$. These effects could be explained by a large and uniform grain size, and by a lower final density of specimens with the addition of $Nb_2O_5$ and $V_2O_5$ respectively.

• Journal of the Korean Mathematical Society
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• v.47 no.2
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• pp.425-443
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• 2010

We investigate the Schr$\ddot{o}$dinger type operator $H_2\;=\;(-\Delta_{\mathbb{H}^n})^2+V^2$ on the Heisenberg group $\mathbb{H}^n$, where $\Delta_{\mathbb{H}^n}$ is the sublaplacian and the nonnegative potential V belongs to the reverse H$\ddot{o}$lder class $B_q$ for $q\geq\frac{Q}{2}$, where Q is the homogeneous dimension of $\mathbb{H}^n$. We shall establish the estimates of the fundamental solution for the operator $H_2$ and obtain the $L^p$ estimates for the operator $\nabla^4_{\mathbb{H}^n}H^{-1}_2$, where $\nabla_{\mathbb{H}^n}$ is the gradient operator on $\mathbb{H}^n$.

• Animal Bioscience
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• v.36 no.1
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• pp.43-52
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• 2023

Objective: This study aimed to examine the influence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on pregnancy in cytokeratin-18 (K18)-hACE2 transgenic mice. Methods: To determine the expression of hACE2 mRNA in the female reproductive tract of K18-hACE2 mice, real-time polymerase chain reaction (RT-PCR) was performed using the ovary, oviduct, uterus, umbilical cord, and placenta. SARS-CoV-2 was inoculated intranasally (30 μL/mouse, 1×10⁴ TCID₅₀/mL) to plug-checked K18-hACE2 homozygous female mice at the pre-and post-implantation stages at 2.5 days post-coitum (dpc) and 15.5 dpc, respectively. The number of implantation sites was checked at 7.5 dpc, and the number of normally born pups was investigated at 20.5 dpc. Pregnancy outcomes, including implantation and childbirth, were confirmed by comparison with the non-infected group. Tissues of infected mice were collected at 7.5 dpc and 19.5 dpc to confirm the SARS-CoV-2 infection. The infection was identified by performing RT-PCR on the infected tissues and comparing them to the non-infected tissues. Results: hACE2 mRNA expression was confirmed in the female reproductive tract of the K18-hACE2 mice. Compared to the non-infected group, no significant difference in the number of implantation sites or normally born pups was found in the infected group. SARS-CoV-2 infection was detected in the lungs but not in the female reproductive system of infected K18-hACE2 mice. Conclusion: In K18-hACE2 mice, intranasal infection with SARS-CoV-2 did not induce implantation failure, preterm labor, or miscarriage. Although the viral infection was not detected in the uterus, placenta, or fetus, the infection of the lungs could induce problems in the reproductive system. However, lung infections were not related to pregnancy outcomes.

• Journal of the Korean Ceramic Society
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• v.54 no.5
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• pp.406-412
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• 2017

$70V_2O_5-10Fe_2O_3-13P_2O_5-7B_2O_3$ glasses were prepared to study the electrical conductivity and catalytic properties of the structural change with crystallization. The structural changes were analyzed by determining the molecular volume from the sample density; using X-Ray Diffraction (XRD) analysis, which indicated that $V_2O_5$, $VO_2$ and $B_2O_3$ crystals in heat-treated more than 1h samples. Especially a new crystalline phase of non-stoichiometric $Fe_{0.12}V_2O_5$ was formed after 6 h heat treatment. The V-O bonding change after crystallization was analyzed by Fourier Transform Infrared Spectroscopy (FTIR); V ion change from $V^{5+}$ to $V^{4+}$ was shown by XPS. Conductivity and catalytic properties were examined based on the polaronic hopping of V and Fe ions, which exhibited different valence states with crystallization.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.377-380
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• 1997

In order to investigate the electrical characteristics due to the curing condition of silicone gel for Power Semiconductor, the V-I characteristics is studied. For experiment, We have made up several samples of different curing temperature and time such as 1[H],2[H] at 150[$^{\circ}C$], 160[$^{\circ}C$], 170[$^{\circ}C$]. As a result of the V-I characteristics, it is confirmed that the properties of specimen cured at 170[$^{\circ}C$], 2[H] is stable.

• Communications of the Korean Mathematical Society
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• v.9 no.2
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• pp.337-353
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• 1994

Let H be a Schrodinger operator in $L^2$(R) H =(equation omitted) ＋ V(x), with supp V ⊂ [-R, R]. A number $z_{0}$ / in the lower half-plane is called a resonance for H if for all $\phi$ with compact support 〈$\phi$, $(H - z)^{-l}$ $\phi$〉 has an analytic continuation from the upper half-plane to a part of the lower half-plane with a pole at z = $z_{0}$ . Thus a resonance is a sort of generalization of an eigenvalue. For Im k > 0, ($H - k^2$)$^{-1}$ is an integral operator with kernel, given by Green's function(omitted)

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.877-881
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• 2006

We obtained sputtering yields for the MgO, $MgAl_2O_4$ and $MgAl_2O_4/MgO$ films using the FIB system. $MgAl_2O_4/MgO$ protective layers have been found to have less $24^{\sim}^30%$ sputtering yield values from 0.24 atoms/ion up to 0.36 atoms/ion than MgO layers with the values from 0.36 atoms/ion up to 0.45 atoms/ion for irradiated $Ga^+$ ion beam whose energies ranged from 10 keV to 14 keV. And $MgAl_2O_4$ layers have been found to have lowest sputtering yield values from 0.88 up to 0.11. It is also found that $MgAl_2O_4/MgO$ and MgO have secondary electron emission $coefficient({\gamma})$ values from 0.09 up to 0.12 for $Ne^+$ ion whose energies ranged from 50 eV to 200 eV.

• Journal of Environmental Science International
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• v.30 no.6
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• pp.501-505
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• 2021

V₂O₅-TiO₂ catalysts were prepared by various methods. V₂O₅-TiO₂ were prepared by sol-gel method with different drying conditions (aerogel and xerogel), and V₂O₅ supported on TiO₂ obtained by sol-gel method with precipitation-deposition method and impregnation method. The performance of the V₂O₅-TiO₂ catalysts was investigated for the selective oxidation of hydrogen sulfide in the stream containing both ammonia and excess water. All the catalysts showed good dispersion of vanadium and they had high H₂S conversion with no or little production of sulfur dioxide. The V₂O₅-TiO₂ aerogel catalyst prepared by sol-gel method with drying under super critical condition had the highest surface area which led to better catalytic activity compared to those by other synthesis methods.