• 진공이야기
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• 제2권4호
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• pp.9-15
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• 2015

Nonthermal bio-compatible plasma (bioplasma) sources and their characteristics operating at atmospheric pressure could be used for biological cell interactions, especially for plasma bioscience and medicines. The electron temperatures and plasma densities of this bioplasma are measured to be 0.7 ~ 1.8 eV and $(3-5){\times}10^{14-15}cm^{-3}$, respectively. Herein, we introduced general schematic view of the plasma-initiated ultraviolet photolysis of water inside the biological solutions or living tissue for the essential generation mechanism of the reactive hydroxyl radical [OH] and hydrogen peroxide [$H_2O_2$], which may result in apoptotic cell death in plasma bioscience and medicines. Further, we surveyed the various nonthermal bioplasma sources including plasma jet, micro-DBD (dielectric barrier discharge) and nanosecond discharged plasma. The diseased biological protein, cancer, and mutated cells could be treated by these bioplasma sources or bioplasma activated water to result in their apoptosis for new paradigm of plasma bioscience and medicines.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 춘계학술논문발표회 논문집
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• pp.100-103
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• 2008

Autoignition suppression of hydrogen/air premixed mixtures by $CF_3CHFCF_3$(HFP) was investigated computationally. Numerical simulation was performed in isobaric and homogeneous system to evaluate the induction times. The detailed chemistry of 93 species and 817 reaction mechanism was introduced for hydrogen/air/HFP mixtures. The results shows the similar concentrations for the major reactants such as hydrogen and oxygen during autoignition while water vapor produced at the ignition temperature was decomposed later, which leaded to the shoulder on the concentration of H, OH and O radical with time. The fluorine included from HFP was converted mainly to stable HF and the carbon was formed to various species, CF2, CF2O, CO etc. More details of chemical effects of HFP addition will be investigate with sensitivity analysis in the near future.

• Applied Science and Convergence Technology
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• 제23권4호
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• pp.169-178
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• 2014

Fluid model based numerical analysis is done to simulate a low damage etch back system for 20 nm scale semiconductor fabrication. Etch back should be done conformally with very high material selectivity. One possible mechanism is three steps: reactive radical generation, adsorption and thermal desorption. In this study, plasma generation and transport steps are analyzed by a commercial plasma modeling software package, CFD-ACE+. Ar + $CF_4$ ICP was used as a model and the effect of reactive gas inlet position was investigated in 2D and 3D. At 200~300 mTorr of gas pressure, separated gas inlet scheme is analyzed to work well and generated higher density of F and $F_2$ radicals in the lower chamber region while suppressing ions reach to the wafer by a double layer conducting barrier.

• 한국표면공학회지
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• 제32권2호
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• pp.83-92
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• 1999

GaN etching was performed using planar inductively coupled $Cl_2$-based plasmas and the effects of main process parameters on the characteristics of the plasmas and their relations to GaN etch rates were studied. Also, the GaN etch mechanism was investigated using a Langmuir probe and optical emission spectroscopy (OES) during the etching, and X-ray photoelectron spectroscopy (XPS) of the etched surfaces. The GaN etch rates increased with the increase of chlorine radical density and ion energy, and a vertical etch profile haying the etch rate close to 4000 $\AA$/min could be obtained. The addition of 10% Ar to $Cl_2$ gas increased the GaN etch rate and the addition of Ar (more than 20%) and HBr generally reduced the GaN etch rate. The GaN etch rate appeared to be more affected by the chemical reaction between Cl radicals and GaN compared to the physical sputtering itself under the sufficient ion bombardments to break GaN bonds.

• Bulletin of the Korean Chemical Society
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• 제30권10호
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• pp.2377-2380
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• 2009

The treatment of primary amines with amino acids as a CO source in the presence of polyaniline emeraldine salts bring about N-formylation to give the corresponding formamides. This route to N-formylation methodology of primary amine represents the first reported example of a CO-transfer via radical mechanism by highly nanoporous polyaniline emeraldine salts catalyst.

• 대한한의학회지
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• 제21권2호
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• pp.79-86
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• 2000

Objectives and Methods : In order to elucidate toxic mechanism of myocardial damage and protective effect of myrrha water extract against cytotoxic effect of xanthine oxidase/hypoxanthine(XO/HX), cardioprotective effect of myrrha water extract was examined by MTT assay, LDH (Lactate Dehydrogenase) activity and heart beating rate after cultured myocardial cells derived from neonatal mouse were treated with various concentration of XO/HX, a free radical. Results : XO/HX induced a decrease of cell viability, an increase in the amount of LDH, and a decrease of heart beating rate on cultured myocardial cells in a dose-dependent manner. In cardioprotective effect of myrrha water extract, it showed a decrease in the amount of LDH and an increase of heart beating rate on cultured myocardial cells damaged by XO/HX. Conclusions : From the above results, it is suggested that XO/HX showed toxic effect in cultured myocardial cells derived from neonatal mouse and that myrrha water extract is very effective in the prevention of XO/HX-induced cardiotoxicity.

• 대한전기학회논문지
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• 제35권1호
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• pp.17-25
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• 1986

Discussions on this paper are related to the effects of organic materials to treeing phenomena of low density polyethylene. As additives, 11 kinds of organic compounds are selected by considering the respective features such as melting point, boiling point, electron affinity as well as molecular structure, and then the specimens of low density polyethylene are prepared by blending with 10wt% of the selected additives. For the comparison of effectiveness of treeing resistance and interpretation of the mechanism of compounds as treeing retardants, several investigations such as the tree acceleration test, the prestressed test and the measurement of internally occurred partial discharge are carried out. As the results, meta-Cresol is regard as the most effective retardant among those, and it is supposed that this aromatic compound to be comprised of radical having large electron affinity has strong capability to accept energetic electron to prevent or delay the growth of discharge streamer. Furthermore, by activating partial discharge at the wall of tree pit through the function of trapped electron at this material, the gas pressure in the pit is increased up to prevent the growth of streamer.

• Bulletin of the Korean Chemical Society
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• 제26권6호
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• pp.887-891
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• 2005

Novel nickel catalyst deposited on nanoporous carbon was found to be an efficient catalyst for the epoxidation of simple alkenes with $O_2$ and isobutyraldehyde under mild conditions. Alkenes exhibited different reactivities towards Ni-catalyst and epoxidation with stilbene proceeds stereospecifically. This may be rationalized with the mechanism involving coordinated acylperoxy radical intermediate. Nickel contents depend on the preparative methods and the KNI-3 catalyst, which was synthesized by wet impregnation of $Ni(NO_3)_2$ into nanoporous carbon, shows the highest activity. The activity of the catalyst is well correlated with contents of nickel. Recycled catalysts suffer considerable loss of activity due to leaching of catalytic active species, nickel.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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• pp.313-318
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• 2003

Vitamin C's function and mechanism are comparatively well known among the several kinds of vitamins. Inhibition of free radical. promotion of collagen synthesis, restraint of melanin formation and resolution of melanin are its main functions. But Vitamin C is very easy to oxidize by heat, moisture or air so it causes stability problem to make formulation. To solve these problems unique formulating method or derivatives using method could be effective. Object: First, stabilize 10% of Ascorbic acid as polyol/silicone emulsion and try to make polyol/silicone/polyol anhydrous multiple emulsion secondly. And then, encapsulate with porous power to enhance the stability of Ascorbic Acid from formulating method.

• International Journal of Industrial Entomology and Biomaterials
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• 제28권2호
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• pp.85-91
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• 2014

This study was designed to find out the effect of Nosema spore on oxidative damages and antioxidant defence in the midgut of tasar silkworm Antheraea mylitta. Higher level of lipid peroxidation (LPX) and total hydroperoxides indicate the resultant oxidative stress in the Nosema exposed specimen. Increased superoxide dismutase (SOD) suggests activation of physiological mechanism to scavenge the superoxide radical produced during Nosema infection. Higher activities of catalase and glutathione-S-tranferase on $18^{th}$ d indicate adaptive behaviour of the tissue against oxyradicals. The results suggest that Nosema infection is involved in altering the active oxygen metabolism by modulating LPX and reactive oxygen species (ROS), which is indicative of pebrine disease disorder.