• Bulletin of the Korean Chemical Society
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• 제34권2호
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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.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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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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• 제26권6호
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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.

• 대한기계학회논문집B
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• 제30권5호
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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.

• 한국식생활문화학회지
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• 제34권5호
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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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• 제55권8호
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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.

• 한국약용작물학회지
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• 제12권4호
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• pp.321-327
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• 2004

한약재로서 혼용되고 있는 느릅나무 및 시무나무의 수피와 근피의 항산화활성 및 총페놀 함량의 차이를 구명하고자 본 연구를 수행하였으며 그 결과는 다음과 같다. DPPH 라디칼에 대해 느릅나무 근피와 수피의 80% 에탄올 추출물은 $10\;{\mu}g/ml$의 농도에서도 각각 41.4% 및 35.6%의 활성을 보여 다른 추출물의 활성 $(2.3{\sim}24.0%)$에 비해 우수한 효과를 가지는 것을 알 수 있었고, superoxide 라디칼에 대해서는 $200{\sim}5\;{\mu}g/ml$의 농도에서 느릅나무 및 시무나무의 수피와 근피로부터 얻어진 모든 추출물이 항산화제인 ascorbic acid보다 우수한 활성을 나타내었으며 특히 느릅나무 근피의 80% 에탄올 추출물과 물 추출물이 좀 더 높은 활성을 나타내었다. 사람의 저밀도지단백 (LDL) 산화에 대한 실험 결과 느릅나무 수피 및 근피의 80% 에탄올 추출물이 $10\;{\mu}g/ml$의 농도에서 84.3% 및 81.7%로 다른 추출물들의 활성 $(31.3%{\sim}78.2%)$보다 비교적 높은 것을 확인할 수 있었다. 실험된 모든 추출물은 linoleic acid 과산화에 대해서 ${\alpha}-tocopherol$보다 낮은 저해활성을 나타내었다. 한편, 총페놀 함량은 느릅나무 근피의 80% 에탄올 추출물이 50.8%로 가장 높았으며 시무나무 근피의 물 추출물이 5.6%로 가장 낮았다. 이상의 실험결과, 느릅나무의 근피와 수피가 시무나무의 근피와 수피보다 더 효과적인 항산화 활성을 보유하며 특히, 느릅나무 근피의 80% 에탄올 추출물은 가장 항산화 활성이 우수한 것으로 확인되었다.

• 한국식품조리과학회지
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• 제25권5호
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• pp.521-530
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• 2009

본 연구에서는 들깻잎 분말을 0%, 0.5%, 1%, 3%, 5% 첨가한 쿠키를 제조하여 쿠키의 항산화활성을 입증하고 품질특성을 측정하였다. 들깻잎 분말의 총 페놀 화합물 함량은 $197.33{\pm}14.49mg$ GAE/100 g이며, DPPH 유리 라디칼 소거능은 $100{\mu}g/mL$에서 $35.56{\pm}3.02%$로 나타나 높은 항산화활성을 보여주었다. 제조된 쿠키의 DPPH radical 소거능을 측정하여 항산화 활성을 비교한 결과 들깻잎 분말의 첨가량이 증가함에 따라 항산화활성도 유의적으로 증가하였으며 항산화활성을 가지는 총 페놀 함량도 들깻잎 분말 첨가량 증가에 따라 증가하였다. 또한 이들의 상관관계는 DPPH 라디칼 소거능과 총 페놀 함량이 양의 상관관계 r=0.8994(p<0.001)를 보여주어, 총 페놀 함량이 항산화활성에 영향을 미치는 것으로 나타났다. 항산화활성의 기능성과 함께 제품의 적합성 판단을 위해 반죽의 밀도와 pH, 쿠키의 수분함량, 퍼짐성, 손실률, 팽창률, 색도, 조직감, 관능검사 등의 품질평가를 실시한 결과 반죽의 밀도는 들깻잎 첨가량이 증가할수록 높게 나타났고, pH는 들깻잎 분말 첨가량 증가에 따라 증가되었다. 쿠키의 수분함량은 들깻잎 분말의 첨가량 증가에 따른 유의적 차이가 나지 않았으며, 퍼짐성 지수는 첨가량 증가에 따라 감소하였고, 손실률은 1% 첨가군이 유의적으로 높았으며(p<0.05), 팽창률은 들깻잎 분말 첨가량이 증가할수록 유의적으로 감소되었다(p<0.05). 색도는 쿠키에 첨가된 들깻잎 분말과 쿠키를 굽는 과정에서 생기는 마이얄 반응과 카라멜 반응 등이 영향을 주어, 들깻잎 분말의 첨가량이 증가할수록 L값과 b값이 낮아지고, a값이 높아졌으며 경도는 들깻잎 분말 첨가 농도가 증가함에 따라 높아졌지만 유의적인 차이는 나지 않았다. 그리고 기호도 검사에서 외관, 향미, 맛, 조직감, 전반적인 기호도를 평가한 결과 들깻잎 분말을 1%와 3% 첨가한 들깻잎 쿠키가 유의적으로 높은 기호도를 보였으며 들깻잎 특성 강도에서는 색과 들깻잎 향미, 후미에서 5% 첨가군이 가장 강하였고 느끼한 향미와 단맛은 대조군이 가장 강하다는 결과를 얻었다. 고소한 맛에서는 1% 첨가군이, 부드러운 정도는 0.5% 첨가군이 유의적으로 가장 높은 점수를 받았다(p<0.05). 이러한 결과로 보아 쿠키에 들깻잎 분말을 첨가하는 것은 쿠키의 기호도를 증가시켜주고 동시에 총 페놀함량과 DPPH 라디칼 소거능을 높여주어 쿠키의 가치를 높일 수 있어 바람직할 것으로 사료되며 쿠키제조 시 들깻잎 분말을 $1{\sim}3%$ 첨가하는 것이 바람직하다고 생각된다.

• Asian-Australasian Journal of Animal Sciences
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• 제26권5호
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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.