• Bulletin of the Korean Chemical Society
• /
• v.35 no.7
• /
• pp.1927-1928
• /
• 2014

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.338-338
• /
• 2011

The behavior of hydroxide ions on water-ice films was studied by using $Cs^+$ reactive ion scattering (RIS), low energy sputtering (LES) and temperature-programmed desorption (TPD). A $Cs^+$ beam of a low kinetic energy (<100 eV) from $Cs^+$ ion gun was scattered at the film surface, and then $Cs^+$ projectiles pick up the neutral molecules on the surface as $Cs^+$-molecule clusters form (RIS process). In LES process, the preexisting ions on the surface are desorbed by the $Cs^+$ beam impact. The water-ice films made of a thick (>50 BL) $H_2$O layer and a thin $D_2O$ overlayer were controlled in temperatures 90~140K. We prepared hydroxide ions by using Na atoms which proceeded hydrolysis reaction either on the ice film surface or at the interface of the $H_2O$ and $D_2O$ layers.[1] The migration of hydroxide ions from the $H_2O/D_2O$ interface to the top of the film was examined as afunction of time. From this experiment, we show that hydroxide ions tend to reside at the water-ice surface. We also investigated the H/D exchange reactions of $H_2O$ and $D_2O$ molecules mediated by hydroxide ions to reveal the mechanism of migration of hydroxide to the ice surface.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.9A
• /
• pp.1276-1284
• /
• 1999

We have evaluated the BER's and CLP's of Wireless ATM (WATM) cells employing the concatenated FEC code with pilot symbols for fading compensation through the simulation in indoor wireless channel modeled as a Rayleigh and a Rician fading channel, respectively. The results of the performance evaluation are compared with those obtained by employing the convolutional code in the same condition. In Rayleigh fading channel, considering the maximum tolerance BER ( $10^-3$) as a criterion of the voice service, it is blown that the performance improvement of about 4 dB is obtained in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols rather than the convolutional code with pilot symbols.When the values of K parameter which means the ratio of the direct signal to scattered signal power in Rician fading channel are 6 and 10, it is shown that the performance improvement of about 4 dB and 2 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols considering the maximum tolerance BER of the voice service. Also in Rician fading channel of K=6 and K= 10, considering CLP = $10^-3$ as a criterion, it is observed that the performance improvement of about 3.5 dB and1.5 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols.

• Korean Journal of Pharmacognosy
• /
• v.46 no.2
• /
• pp.133-139
• /
• 2015

Two coumarinolignans, cleomiscosins C (1) and D (2) were isolated from the heartwood of Acer mono, together with four compounds, 5-O-methyl-(E)-resveratrol-3-O-${\beta}$-D-glucopyranoside (3), 5-O-methyl-(E)-resveratrol-3-O-${\beta}$-D-apiofuranosyl-(1$\rightarrow$6)-${\beta}$-D-glucopyranoside (4), scopoletin (5), and (E)-resveratrol-3-O-${\beta}$-D-glucopyranoside (6). Of them, cleomiscosins C (1) and D (2) were applied to preparing inclusion complex molecules with ${\beta}$-cyclodextrin (${\beta}$-CD) to improve the very poor solubility in cell media. The CD complexes of 1 and 2 exhibited an enhancement of water solubility which is feasible to measure their cytotoxicity using a spectrophotometer in a cell-based assay. Anti-proliferative activity of these complex molecules was successfully estimated on HCT116 human colon cancer cells, and cleomiscosin D (2) showed anti-proliferative effects at the concentration of 1.95~31.2 ${{\mu}g}$/mL in a dose-dependent manner.

• Journal of the Korean Chemical Society
• /
• v.17 no.2
• /
• pp.85-94
• /
• 1973

The stability constants of the charge-transfer complexes formed between three derivatives of nitrobenzene, i.e., 1,3,5-trinitrobenzene, m-dinitrobenzene, nitrobenzene and eleven organic molecules such as $\alpha-picoline$, pyridine, dimethylsulfoxide, N, N'-dimethylacetamide, tetrahydrofurane, 1, 4-dioxane, diethyl ether, acetonitrile, propylene oxide, epichlorohydrine, and methyl acetate, have been determined by ultraviolet absorption spectroscopy in carbon tetrachloride solution at 25.0$^{\circ}C$. The parameters of the electrostatic effect ($E_D$) and covalent effect ($C_D$) for the eleven organic compounds have been calculated from the modified equation of the double-scale enthalpy,$logK = E_AC_A+E_DC_D$ and also the shift of C=O vibrational frequency in infrared spectra for N,N'-dimethylacetamide have been measured from the solutions of above organic compounds. The empirical equation, ${\Delta}{\nu}_{C=O} = 37.4-5.47E_D+12.1C_D$, related to the parameters and the frequency shift has been derived. It seems that the stabilities of the complexes principally depend on the covalent effect. Especially it is found that $\pi$ orbitals in molecules, in addition to the parameters, play the important role in forming the charge-transfer complexes.

• Journal of the Korean Magnetics Society
• /
• v.7 no.6
• /
• pp.285-292
• /
• 1997

We have studied magnetoelectric effect with cobalt ferrite-Pb(Zr, Ti) $O_3$ composites made by solid state reaction. The maximum magnetoelectric voltage coefficient, $(dE/ dH)_{max}$, increased with longer sintering time and higher volume fraction of the cobalt ferrite. The magnetic field for $(dE/ dH)_{max}$ became lower with increasing the sintering time and decreasing the volume fraction of the cobalt ferrite. The phenomena were explained in terms of grain size change, mechanical coupling efficiency, easiness of magnetization and polarization. We obtained the highest magnetoelectric voltage coefficient of 0.174V/cm-Oe, which is about 30% higher than the best value reported.

• Journal of the Korean Chemical Society
• /
• v.53 no.1
• /
• pp.7-16
• /
• 2009

The global minimum structures of the benzene-water, Bz-$H_2O$ and benzene-water cation complex, [Bz-$H_2O]^+$ have been investigated using ab initio and density functional theory(DFT) with very large basis sets. The highest levels of theory employed in this study are B3LYP/cc-pVQZ for geometry optimization and MP2/aug-cc-pVTZ//B3LYP/aug-cc-pVTZ for binding energy. The harmonic vibrational frequencies and IR intensities are also determined at the various levels of theory to confirm whether the structure of water complex is affected by the presence of benzene. The binding energies of Bz-$H_2O$ (N-1) structure are predicted to be 3.92 kcal/mol ($D_e$) and 3.11 kcal/mol ($D_0$) after the zero-point vibrational energy correction at the MP2/cc-pVQZ//B3LYP/cc-pVQZ level of theory. The binding energies of [Bz-$H_2O]^+$ (C-1) structure are predicted to be 9.06 kcal/mol for $D_e$ and 7.82 kcal/mol for $D_0$ at the same level of theory.

• Journal of IKEEE
• /
• v.27 no.4
• /
• pp.399-404
• /
• 2023

In this paper, we analyzed the current path in the O/N/O (Oxide/Nitride/Oxide) structure of 3D NAND Flash memory and in the O/N/F (Oxide/Nitride/Ferroelectric) structure where the blocking oxide is replaced by a ferroelectric. In the O/N/O structure, when V_read is applied, a current path is formed on the backside of the channel due to the E-fields of neighboring cells. In contrast, the O/N/F structure exhibits a current path formed on the front side due to the polarization of the ferroelectric material, causing electrons to move toward the channel front. Additionally, we performed an examination of device characteristics considering channel thickness and channel length. The analysis results showed that the front electron current density in the O/N/F structure increased by 2.8 times compared to the O/N/O structure, and the front electron current density ratio of the O/N/F structure was 17.7% higher. Therefore, the front current path is formed more effectively in the O/N/F structure than in the O/N/O structure.

• Journal of Electrochemical Science and Technology
• /
• v.8 no.2
• /
• pp.96-100
• /
• 2017

Iridium(III) bis(2-phenylpyridinato-$N,C^{2^{\prime}}$)acetylacetonate ($(ppy)_2Ir(acac)$), a green dopant used in organic light-emitting devices (OLEDs), was subjected to electrochemical characterization to estimate its formal oxidation potential ($E^{o^{\prime}}$), HOMO energy level ($E_{HOMO}$), electron transfer rate constant ($k^{o^{\prime}}$), and diffusion coefficient ($D_o$). The employed combination of voltammetric methods, i.e., cyclic voltammetry (CV), chronocoulometry (CC), and the Nicholson method, provided meaningful insights into the electron transfer kinetics of $(ppy)_2Ir(acac)$, allowing the determination of $k^{o^{\prime}}$ and $D_o$. The quasi-reversible oxidation of $(ppy)_2Ir(acac)$ furnished information on $E^{o^{\prime}}$ and $E_{HOMO}$, allowing the latter parameter to be easily estimated by electrochemical methods without relying on expensive and complex ultraviolet photoemission spectroscopic (UPS) measurements.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.45-49
• /
• 2001

We have investigated physical and electrical properties of the Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin film for alternative gate dielectrics in the metal-oxide-semiconductor device. The oxidation of Hf deposited directly on the Si substrate results in the H $f_{x}$/ $O_{y}$ interfacial layer and the high-k Hf $O_2$film simultaneously. Interestingly, the post-oxidation N2 annealing of the H102/H1Si70y thin films reduces(increases) the thickness of an amorphous HfS $i_{x}$/ $O_{y}$ layer(Hf $O_2$ layer). This phenomenon causes the increase of the effective dielectric constant, while maintaining the excellent interfacial properties. The hysteresis window in C-V curves and the midgap interface state density( $D_{itm}$) of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin films less than 10 mV and ~3$\times$10$^{11}$ c $m^{-2}$ -eV without post-metallization annealing, respectively. The leakage current was also low (1$\times$10-s A/c $m^2$ at $V_{g}$ = +2 V). It is believed that these excellent results were obtained due to existence of the amorphous HfS $i_{x}$/ $O_{y}$ buffer layer. We also investigated the charge trapping characteristics using Fowler-Nordheim electron injection: We found that the degradation of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ gate oxides is more severe when electrons were injected from the gate electrode.e electrode.e.e electrode.e.