• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.201-206
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• 2013

The second-order rate constants have been measured spectrophotometrically for the reactions of paraoxon 1 and parathion 2 with a series of alicyclic secondary amines, $OH^-$ and $HOO^-$ ions in $H_2O$ at $25.0{\pm}0.1^{\circ}C$. A linear Br${\o}$nsted-type plot with ${\beta}_{nuc}$ = 0.40 was obtained for the reactions of 1 with amines and $OH^-$. The reaction has been concluded to proceed through a concerted mechanism. $HOO^-$ deviates positively from the linear Br${\o}$nsted-type plot, implying that the ${\alpha}$-effect is operative. The magnitude of the ${\alpha}$-effect ($k_{HOO^-}/k_{OH^-}$) was found to be ca. 55 for the reaction of 1 and 290 for that of parathion 2, indicating that $HOO^-$ is highly effective in decomposition of the toxic phosphorus compounds although it is over 4 $pK_a$ units less basic than $OH^-$. Among the theories suggested as origins of the ${\alpha}$-effect (e.g., TS stabilization through an intramolecular Hbonding interaction, solvent effect, and polarizability effect), polarizability effect appears to be the most important factor for the ${\alpha}$-effect in this study, since the polarizable $HOO^-$ exhibits a larger ${\alpha}$-effect for the reaction of the more polarizable substrate 2.

• Atmosphere
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• v.27 no.4
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• pp.385-398
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• 2017

Numerical weather prediction experiments were carried out by applying topographic effects to reduce or enhance the solar radiation by terrain. In this study, x and ${\kappa}({\phi}_o,\;{\theta}_o)$ are precalculated for topographic effect on high resolution numerical weather prediction (NWP) with 1 km spatial resolution, and meteorological variables are analyzed through the numerical experiments. For the numerical simulations, cases were selected in winter (CASE 1) and summer (CASE 2). In the CASE 2, topographic effect was observed on the southward surface to enhance the solar energy reaching the surface, and enhance surface temperature and temperature at 2 m. Especially, the surface temperature is changed sensitively due to the change of the solar energy on the surface, but the change of the precipitation is difficult to match of topographic effect. As a result of the verification using Korea Meteorological Administration (KMA) Automated Weather System (AWS) data on Seoul metropolitan area, the topographic effect is very weak in the winter case. In the CASE 1, the improvement of accuracy was numerically confirmed by decreasing the bias and RMSE (Root mean square error) of temperature at 2 m, wind speed at 10 m and relative humidity. However, the accuracy of rainfall prediction (Threat score (TS), BIAS, equitable threat score (ETS)) with topographic effect is decreased compared to without topographic effect. It is analyzed that the topographic effect improves the solar radiation on surface and affect the enhancements of surface temperature, 2 meter temperature, wind speed, and PBL height.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2271-2276
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• 2014

Second-order rate constants ($k_N$) have been measured spectrophotometrically for the reaction of 4-chloro-2-nitrophenyl X-substituted-benzoates (6a-6h) with a series of primary amines including hydrazine in 80 mol % $H_2O$/20 mol % DMSO at $25.0^{\circ}C$. The Br${\o}$nsted-type plot for the reaction of 4-chloro-2-nitrophenyl benzoate (6d) is linear with ${\beta}_{nuc}$ = 0.74 when hydrazine is excluded from the correlation. Such a linear Br${\o}$nsted-type plot is typical for reactions reported previously to proceed through a stepwise mechanism in which expulsion of the leaving group occurs in the rate-determining step (RDS). The Hammett plots for the reactions of 6a-6h with hydrazine and glycylglycine are nonlinear. In contrast, the Yukawa-Tsuno plots exhibit excellent linear correlations with ${\rho}_X$ = 1.29-1.45 and r = 0.53-0.56, indicating that the nonlinear Hammett plots are not due to a change in RDS but are caused by resonance stabilization of the substrates possessing an electron-donating group (EDG). Hydrazine is ca. 47-93 times more reactive than similarly basic glycylglycine toward 6a-6h (e.g., the ${\alpha}$-effect). The ${\alpha}$-effect increases as the substituent X in the benzoyl moiety becomes a stronger electron-withdrawing group (EWG), indicating that destabilization of the ground state (GS) of hydrazine through the repulsion between the nonbonding electron pairs on the two N atoms is not solely responsible for the substituent-dependent ${\alpha}$-effect. Stabilization of transition state (TS) through five-membered cyclic TSs, which would increase the electrophilicity of the reaction center or the nucleofugality of the leaving group, contributes to the ${\alpha}$-effect observed in this study.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.292-295
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• 1999

We investigated the effects of Pd impurities on cube-textures in cold rolled and recrystallized PtPd tapes The sample were made from Pt$_{1-x}Pd_x$ alloys (x from 0 to0.34) by rolling at low temperature. The thickness of the tapes were about 100 ${\mu}$m. The PtPd[111] pole figures of X-ray Diffraction for all the samples indicated similar deformed textures. But the recrystallized textures after annealing showed that a better cube texture was formed in the sample of larger x. The final textures were sensitive to annealing time and temperature when x was increased.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.925-930
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• 2006

Chitosan-based nanocomposite films were prepared using a solution intercalation method incorporating varying amounts of organically modified montmorillonite (Cloisite 30B) from 0 to 30 wt%. The nanocomposite films prepared were optically clear despite a slight decrease in the transmittance due to the spatial distribution of nanoclay. X-ray diffraction patterns indicated that a certain degree of intercalation or exfoliation formed when the amount of clay in the film was low and that microscale tactoids formed when the clay content in the sample was high (more than 10 wt%). The tensile strength (TS) of the chitosan film increased when the clay was incorporated up to 10 wt% and then decreased with further increases in the clay content of the film. The elongation at break (E) increased slightly upon the addition of low levels of clay up to 5 wt% and then decreased with further increases in the amount of the clay in the film. The water vapor permeability (WVP) decreased exponentially with increasing clay content. The water solubility (WS) and swelling ratio (SR) of the nanocomposite films decreased slightly, indicating that the water resistance of the chitosan film increased due to the incorporation of the nanoclay.

• The Korean Journal of Emergency Medical Services
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• v.5 no.1
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• pp.15-22
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• 2001

This study has measured the pulmonary function by treadmill test for 6 young women who were in twenties, and analyzed the respiratory-circulatory function and the change of hormone and immune response after performing the exercise program (60% severity) for 10 weeks. The results are as follows; 1. 10 weeks regular exercise made a decrease in weight and body fat proportion, and improved the respiratory-circular function by increasing the maximum oxygen absorption and ventilation. 2. 10 weeks regular exercise made a significant increase in count of WBC, lymphocyte, and T lymphocyte, but a significant decrease in B lymphocyte. NK cell also showed an increase in counts, but insignificant. 3. 10 weeks regular exercise made a significant increase in blood norepinephrine level. Epinephrine and cortisol also showed an increase in count, but insignificant. In summary, it suggested that 10 weeks regular exercise improves the immune function by decrease in body fat, increase in respiratory-circular function and metabolic efficiency, and also by raising Th/Ts ratio (an increase in count of WBC, lymphocyte, and T lymphocyte, but a decrease in suppressor T lymphocyte).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.139-142
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• 1994

Ceramic filter using energy trapping pheonomenon is used bandpass filter at high frequency. In this paper, we analyzed theoretically ceramic filter characteristics of TS vibrational mode and also investigated experimentally it. The ceramic plate is PZT-4 poled in the thickness direction of Valpey Fisher Co. and electroded with two pairs. We analyzed the characteristics in appling to the all constant of ceramic and electrode material each other and vibrational mode. We also measured resonant frequency and bandpass width of the ceramic filter changing the thickness of ceramic plate and electrode spacing. Comparing of falter characteristics, theoretical value nearly corresponded with experimental value. So we saw that we can expect filter characteristics changing the thickness of ceramic plate and electrode spacing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.274-275
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• 2005

The tensile strain dependency of critical current in YBCO coated conductors was examined at 77K and in the self magnetic field. A commercially available YBCO sample with Cu stabilizer layer was supplied. There existed a peak in the relation between the Ie and tensile strain, and the reversible variation of $I_c$ with applied tensile strain was found. In the neutral axis Ni alloy RABiTS-$Y_2O_3$/YSZ/$CeO_2$ buffered YBCO tape, the $I_c$ recovered reversibly until the applied strain reached to about 0.5%, representing that a significant residual compressive strain induced during cooling to 77 K influenced the axial strain tolerance of YBCO conductors. To investigate the strain and stress influence on the $I_c$, the stress-strain characteristics of YBCO conductors measured at 77 K were discussed.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.865-868
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• 1997

Second-order rate constants have been measured spectrophotometrically for the reactions of p-nitrophenyl phenylacetate (1) and benzoate (2) with a series of alicyclic amines in H2O containing 20 mole % DMSO at 25.0 ℃. 1 appears to be more reactive than 2 toward all the amines studied, although phenylacetic acid is a weaker acid than benzoic acid. The higher reactivity of 1 can be attributed to resonance and/or steric effect, since the ground state of 2 can be stabilized by resonance and 1 would experience less steric hindrance due to the presence of CH2 group between phenyl and C=O group. The reactivity of the amines increases with increasing their basicity. The Bronsted-type plots for aminolysis of 1 and 2 show good linearity with βnuc values of 0.81 and 0.85, respectively, indicating that the TS structures of the aminolyses of 1 and 2 are similar. Besides, the linear Bronsted plots obtained in the present system clearly suggest that there is no mechanism change for the given series of the amines and the reactions of 1 and 2 proceed in a same mechanism.

• Journal of the Korean Chemical Society
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• v.63 no.4
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• pp.233-236
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• 2019

In this study, the solvolysis of cyclohexanesulfonyl chloride (1) was studied by kinetics in ethanol-water, methanol-water, acetone-water, and 2,2,2-trifluoroethanol (TFE)-water binary solvent systems. The rate constants were applied to the extended Grunwald-Winstein equation, to obtain the values of m = 0.41 and l = 0.81. These values suggested $S_N2$ mechanism in which bond formation is more important than bond breaking in the transition state (TS). Relatively small activation enthalpy values (11.6 to $14.8kcal{\cdot}mol^{-1}$), the large negative activation entropy values (-29.7 to $-38.7cal{\cdot}mol^{-1}{\cdot}K^{-1}$) and the solvent kinetic isotope effects (SKIE, 2.29, 2.30), the solvolyses of the cyclohexanesulfonyl chloride (1) proceeds via the $S_N2$ mechanism.