• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.426-432
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• 2013

The mechanisms concerning C-Cl activation of $CCl_4$ by $CHBr^{{\cdot}-}$ and $CBr{_2}^{{\cdot}-}$ have been comparatively investigated in theory. Optimized geometries and frequencies of all stationary points on PES are obtained at the BhandHLYP/aug-cc-pVTZ level of theory, and then the energy profiles are refined at the QCISD(T) method with the aug-cc-pVTZ basis by using the BhandHLYP/aug-cc-pVTZ optimized geometries. Our calculated findings suggest that in the title reactions the major mechanisms consist of both Cl-abstraction and $S_N2$ substitution reactions. Also, a succeeding pathway described by electron transfer was revealed before the initial Cl-abstraction products separate. Those are consistent with relevant experimental results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.327-334
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• 2004

Spectroscopic and electrostatic probe measurements were made to examine plasma characteristics with or without a metal plate for a 10-㎾-class direct-current arcjet Heat fluxes into the plate from the plasma were also evaluated with a Nickel slug and thermocouple arrangement. Ammonia and mixtures of nitrogen and hydrogen were used. The NH$_3$ and $N_2$+3H$_2$ plasmas in the nozzle and in the downstream plume without a plate were in thermodynamical nonequilibrium states. As a result, the H-atom electronic excitation temperature and the $N_2$ molecule-rotational excitation temperature intensively decreased downstream in the nozzle although the NH molecule-rotational excitation temperature did not show an axial decrease. Each temperature was kept in a small range in the plume without a plate except for the NH rotational temperature for NH$_3$ gas. On the other hand, as approaching the plate, the thermodynamical nonequilibrium plasma came to be a temperature-equilibrium one because the plasma flow tended to stagnate in front of the plate. The electron temperature had a small radial variation near the plate. Both the electron number density and the heat flux decreased radially outward, and an increase in H$_2$ mole fraction raised them at a constant radial position. In cases with NH$_3$ and $N_2$+3H$_2$ a large number of NH radical with a radially wide distribution was considered to cause a large amount of energy loss, i.e., frozen flow loss, for arcjet thrusters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.25-28
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• 2000

In this study, $Y_2$O$_3$ thin films were etched with inductively coupled plasma (ICP). The etch rate of $Y_2$O$_3$, and the selectivity of $Y_2$O$_3$ to YMnO$_3$ were investigated by varying Cl$_2$/(Cl$_2$+Ar) gas mixing ratio. The maximum etch rate of $Y_2$O$_3$, and the selectivity Of $Y_2$O$_3$ to YMnO$_3$ were 302/min, and 2.4 at Cl$_2$/(Cl$_2$+Ar) gas mixing ratio of 0.2 repectively. In x-ray photoelectron spectroscopy (XPS) analysis, $Y_2$O$_3$ thin film was dominantly etched by Ar ion bombardment, and was assisted by chemical reaction of Cl radical. These results were confirmed by secondary ion mass spectroscopy(SIMS) analysis. YCI, and YCl$_3$ existed at 126.03 a.m.u, and 192.3 a.m.u, respectively

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.201-207
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• 2017

An electron-excited temperature ($T_{ex}$) is not determined by the Boltzmann plots only with the spectral data of $4p{\rightarrow}4s$ in an Ar-plasma jet operated with a low frequency of several tens of kHz and the low voltage of a few kV, while $T_{ex}$ can be obtained at least with the presence of a high energy-level transition ($5p{\rightarrow}4s$) in the high-voltage operation of 8 kV. The optical intensities of most spectra that are measured according to the voltage and the measuring position of the plasma column increase or decay exponentially at the same rate as that of the intensity variation; therefore, the excitation temperature is estimated by comparing the relative optical-intensity to that of a high voltage. In the low-voltage range of an Ar-jet operation, the electron-excitation temperature is estimated as being from 0.61 eV to 0.67 eV, and the corresponding radical density of the Ar-4p state is in the order of $10^{10}{\sim}10^{11}cm^{-3}$. The variation of the excitation temperature is almost linear in relation to the operation voltage and the position of the plasma plume, meaning that the variation rates of the electron-excitation temperature are 0.03 eV/kV for the voltage and 0.075 eV/cm along the plasma plume.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.397-404
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• 2006

Effects of surface defect distribution on flame instability during flame-surface interaction are experimentally investigated. To examine chemical quenching phenomenon which is caused by radical adsorption and recombination processes on the surface, thermally grown silicon oxide plates with well-defined defect density were prepared. ion implantation technique was used to control the number of defects, i.e. oxygen vacancies. In an attempt to preferentially remove oxygen atoms from silicon dioxide surface, argon ions with low energy level from 3keV to 5keV were irradiated at the incident angle of $60^{\circ}$. Compositional and structural modification of $SiO_2$ induced by low-energy $Ar^+$ ion irradiation has been characterized by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). It has been found that as the ion energy is increased, the number of structural defect is also increased and non-stoichiometric condition of $SiO_x({\le}2)$ is enhanced.

• Journal of the Korean Society of Food Culture
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• v.34 no.5
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• pp.612-619
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• 2019

This study assessed the quality characteristics of cookies made with different amounts (0, 5, 10, 15%) of black carrot powder. The density and pH value of cookie dough were constant for all groups. Compared to the control group, the moisture content was higher in groups containing the black carrot powder. Increasing the amount of black carrot powder resulted in decreased L-value but increased a-value. Furthermore, the hardness of cookies increased with increasing amounts of black carrot powder. The consumer acceptance test revealed that up to 15% black carrot powder addition was desirable. Total phenol content of the control group was 24.0 mg GAE/100 g, while black carrot powder groups ranged from 45.5 to 103.5 mg GAE/100 g. The DPPH radical scavenging activity was also augmented with increasing volumes of black carrot powder. Taken together, we recommend that cookies with 15% black carrot powder are desirable in terms of overall acceptability and antioxidant activity.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2879-2888
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• 2023

In fusion environments, large scales of helium (He) atoms are produced by a radical transformation along with structural damage in structural materials, resulting in material swelling and degradation of physical properties. To understand its irradiation effects, this paper investigates the stability, electronic structure, energetics, charge density distribution, PDOS and TDOS, and diffusion processes of He impurities in 6HSiC materials. The formation energy indicates that a stable, favorable position for interstitial He is the HR site with the lowest energy of 2.40 eV. In terms of vacancy, the He atom initially prefers to substitute at pre-existing Si vacancy than C vacancy due to lower substitution energy. The minimum energy paths (MEPs) with migration energy barriers are also calculated for He impurity by interstitial and vacancy-mediated diffusion. Based on its calculated energy barriers, the most possible diffusion path includes the exchange of interstitial and vacancy sites with effective migration energies ranging from 0.101 eV to 1.0 eV. Our calculation provides a better understanding of the stabilization and diffusion behaviors of He impurities in 6H-SiC materials.

• Korean Journal of Medicinal Crop Science
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• v.12 no.4
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• pp.321-327
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• 2004

Cortex of Ulmus davidiana var. japonica N. and Hemipteleae davidii P. have been used without classification according to countries as oriental medicine for treatment of various disorders. This study was conducted to elucidate the difference in antioxidant activity and total phenol content of these medicinal materials. Root cortex and trunk cortex of two medicinal plants were extracted with 80% ethanol $(at\;85^{\circ}C)$ and water (at room temperature), respectively. All of the extracts at $200{\sim}5\;{\mu}g/ml$, showed more effective scavenging activity on superoxide radical than ascorbic acid, and 80% ethanol and water extracts of Ulmus root cortex (URC) was more effective. Scavenging activities on DPPH radical of 80% ethanol extracts from URC and Ulmus trunk cortex (UTC) at 10 ${\mu}g/ml$, (41.4, 35.6%) were higher than those of the other six extracts and ${\alpha}-tocopherol\;(2.3{\sim}24.0%)$. Inhibitory activities on human low density lipoprotein (LDL) oxidation of 80% ethanol extracts from UTC and URC (84.3, 81.7%) at $10\;{\mu}g/ml\;(31.3{\sim}78.2%)$ were higher than those of the other six extracts and ${\alpha}-tocopherol$. However, antioxidant activities on linoleic acid peroxidation of all of the extracts were relatively lower than that ${\alpha}-tocopherol$. Total phenol content of 80% ethanol extract from URC was the highest value as 50.8% and that of water extract from HRC was the lowest as 5.6% among the extracts. From these results, it is suggested that Ulmus root cortex was the most effective in antioxidant activity.

• Korean journal of food and cookery science
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• v.25 no.5
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• pp.521-530
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• 2009

Perilla leaves powder was added to cookies to determine a practical use for the herb, which has been shown to have medical benefits and functionality. We examined the antioxidant activity and quality characteristics of cookies prepared with different amounts (as ratios of 0.5%, 1%, 3%, 5% to the total materials) of perilla leaves powder. The antioxidant activity was estimated by DPPH free radical scavenging activity and the total phenolic compound content in perilla leaves powder and cookies. The quality characteristics of the perilla leaves cookie were estimated in terms of the bulk density, pH of the dough, spread factor, loss rate, leavening rate, color, texture profile analysis, and sensory evaluations. While the bulk density and pH of the dough as well as total polyphenol contents and DPPH free radical scavenging activity of cookies significantly increased, the spread factor, loss rate, leavening rate and L value of the cookies decreased with increasing perilla leaves powder content(p<.05). The consumer acceptability scores for the $1{\sim}3%$ perilla leaves cookie groups ranked significantly(p<.05) higher than those of the other groups in appearance, taste, flavor, texture, and overall preference. This study suggests that perilla leaves powder is a good ingredient to increase the consumer acceptability and the functionality of cookies.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.5
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• pp.675-682
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• 2013

One hundred and sixty Taiwan country chickens (d-old chicks) were randomly assigned into four groups with four replicates and equal sex. Basal diets were supplemented with 0, 0.5, 1 and 2% of Bazhen powder, a traditional Chinese herbal medicine complex. The study was conducted for 14 wks. Experimental results indicated that Bazhen supplement did not influence feed intake, body weight gain and feed:gain ratio. Compared with control group, the percentage of serum HDL (high-density lipoprotein) linearly increased (p<0.03) and that of VLDL+LDL (very low-density+low-density lipoprotein) linearly decreased (p<0.03) in Bazhen supplemented groups, that 2% Bazhen was significantly different with control group (p<0.05). Chickens fed diets containing 2% Bazhen displayed reduced (p<0.05) serum GOT (glutamic-oxaloacetic transaminase) levels. The IgG, ${\gamma}$-globulin levels and PHA (phytohemagglutinin) skin challenge results in 1% Bazhan supplemented group were higher (p<0.05) than in the control group, the SRBC (sheep red blood cell) and ND (newcastle disease) titers in Bazhen supplemented groups were linear higher (p<0.05) than in the control group. The liver catalase activity and the capacity of scavenging DPPH (${\alpha}$-${\alpha}$-diphenyl-${\beta}$-picrylhydrazyl) radical were linearly increased (p<0.03) in Bazhen supplemented groups, and the 1 and 2% groups were different from the control group (p<0.05). Liver TBARS (thiobarbituric acid-reactive substances) levels in all Bazhen supplemented groups and total glutathione level in the 2% group were reduced (p<0.05) compared to the control group and displayed a linear response (p<0.05). The TBA (thiobarbituric acid) and pH value of the breast muscle after 24 h post-mortem in the Bazhen supplemented groups was linear lower (p<0.05) than in the control group. Results from this study demonstrated that Bazhen supplement in chicken had several beneficial effects, including increased SRBC and ND titers, HDL and IgG, ${\gamma}$-globulin levels, PHA skin challenge result, decreased VLDL+LDL and GOT levels, and displayed antioxidation effects in serum and carcass meat parameters.