• The Korean Journal of Food And Nutrition
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• v.28 no.1
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• pp.34-39
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• 2015

In this study, portective effect on DNA damage several mushrooms (Pleurotus ostreatus, Flammulina velutipes, Lentinula edodes) according to cooking methods was investigated using Comet assay. Three edible mushrooms were cooked by grilling, blanching, pan-frying, or by preparing 'Jeon' (traditional Korean pancake). Cells were incubated in medium with 4 kinds of samples for 48 h ($37^{\circ}C$) were further treated with hydrogen peroxide ($H_2O_2$) for 5 min as an oxidative stimulus. Oxidative damage was evaluated by single-cell gel electrophoresis (Comet assay) and quantified by tail DNA% (TD), tail length (TL), tail moment (TM). Though oxidative DNA damages expressed as TD, TL, TM of 4 cooked samples were higher than raw sample, which means lower protective activities, all samples including raw sample had significantly higher protective effects than the positive control (p<0.05). The protective effect on DNA damage of cooked samples decreased much more when soybean oil added, likely due to the thermal oxidation of oil during cooking. Although heat treatment could degrade protective effect on DNA damage of mushrooms, the cooked mushroom had significant effect on oxidative stress. In conclusion, grilling and blanching were the most advantageous cooking methods to protect oxidative DNA damage induced by $H_2O_2$.

• Korean Journal of Materials Research
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• v.10 no.9
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• pp.601-606
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• 2000

Nickel mono-silicide(NiSi) shows no increase of resistivity as the line width decreases below 0.15$\mu\textrm{m}$. Furthermore, thin silicide can be made easily and restrain the redistribution of dopants, because NiSi in created through the reaction of one nickel atom and one silicon atom. Therefore, we investigated the deposition condition of Ni films, heat treatment condition and basic properties of NiSi films which are expected to be employed for sub-0.15$\mu\textrm{m}$ class devices. The nickel silicide film was deposited on the Si wafer by using a dc-magnetron sputter, then annealed at the temperature range of $150~1000^{\circ}C$. Surface roughness of each specimen was measured by using a SPM (scanning probe microscope). Microstructure and qualitative composition analysis were executed by a TEM-EDS(transmission electron microscope-energy dispersive x-ray spectroscope). Electrical properties of the materials at each annealing temperature were measured by a four-point probe. As the results of our study, we may conclude that; 1. SPM can be employed as a non-destructive process to monitor NiSi/NiSi$_2$ transformation. 2. For annealing temperature over $800^{\circ}C$, oxygen pressure $Po_2$ should be kept below $1.5{\times}10^{-11}torr$ to avoid oxidation of residual Ni. 3. NiSi to $NiSi_2$ transformation temperature in our study was $700^{\circ}C$ from the four-point probe measurement.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.8
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• pp.1262-1267
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• 2004

An anticoagulant was purified from corn silk which has been used in Oriental Medicine. The anticoagulant from corn silk has a molecular mass of 135 kDa, and purified by 24 folds with a recovery of 11%. It was not sensitive to heat and protease treatment. However, periodate oxidation of the anticoagulant resulted in loss of activity significantly, implying that a carbohydrate was responsible for an anticoagulant activity. Galactose, glucose, mannose, fucose, glucosamine, and galactosamine were detected after acid hydrolysis by thin layer chromatography (TLC) and Bio-LC. It was confirmed that anticoagulant had OH and NH bonds by IR, supporting that the anticoagulant is composed of neutrosugar and aminosugar. Its anticoagulating activity was measured by delay in thrombin time (TT) and prothrombin time (PT) without affecting clotting by snake venom and delay in activated partial thromboplastin time (APTT). TT was more sensitive than PT, and was delayed two and three times at the concentration of 60 and 88 nM, respectively. The anticoagulating activity was reduced in the thrombin-induced clotting assay using purified fibrinogen according to the increase of fibrinogen concentration with the apparent Ki value of 23 nM.

• Journal of the Korean Electrochemical Society
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• v.11 no.4
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• pp.284-288
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• 2008

Sn-thin film as high capacitive anode for thin film lithium-ion battery was prepared by organic-electrolyte electroplating using Sn(II) acetate. Electrolytic solution including $Li^+$ and $Sn^{2+}$ had 3 reduction peaks at cyclic voltammogram. Current peak at $2.0{\sim}2.5\;V$ region correspond to the electroplating of Sn on Ni substrate. This potential value is lower than 2.91 V vs. $Li^+/Li^{\circ}$, of the standard reduction potential of $Sn^{2+}$ under aqueous media. It is the result of high overpotential caused by high resistive organic electrolytic solution and low $Sn^{2+}$ concentration. Physical and electrochemical properties were evaluated using by XRD, FE-SEM, cyclic voltammogram and galvanostatic charge-discharge test. Crystallinity of electroplated Sn-anode on a Ni substrate could be increased through heat treatment at $150^{\circ}C$ for 2 h. Cyclic voltammogram shows reversible electrochemical reaction of reduction(alloying) and oxidation(de-alloying) at 0.25 V and 0.75 V, respectively. Thickness of Sn-thin film, which was calculated based on electrochemical capacity, was $7.35{\mu}m$. And reversible capacity of this cell was $400{\mu}Ah/cm^2$.

• Journal of Life Science
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• v.20 no.1
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• pp.113-118
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• 2010

The study was conducted to identify volatile flavor compounds in concentrated onion extracts ($Oniwell^{TM}$) during storage at $30^{\circ}C$ for 150 days. A total of 23 compounds was detected in samples by solid phase microextraction (SPME)/GC/MSD, consisting mainly of 9 sulfur-containing compounds, 5 carbonyl compounds, 4 furans, 2 aromatic compounds and 3 miscellaneous compounds. The sulfur-containing compounds were major compounds with ranges of 75.8~67.3% of total volatiles. In particular, dimethyl trisulfide, with a cooked cabbage-like odor, was 50.1~42.1% of the total amount of sulfur-containing compounds. Two compounds, dimethyl disulfide (fresh garlic/green onion-like) and methylpropyl disulfide (garlic salt-like), were significantly increased with longer storage periods (p<0.05). Four furans (furfural, 2-acetylfurn, 5-methyl-2-furfural, furfurylalcohol), known as thermally generated flavors, ranged from 14.2~12.9% of total volatiles, and the amounts of 4 aldehydes (2-, 3-methylbutanal, benzaldehyde, phenylactaldehyde) derived from lipid oxidation during heat treatment were followed in that order. Accordingly, it was estimated that these 3 groups including sulfur-containing compounds, furans and aldehydes played key roles in flavors in concentrated onion extracts ($Oniwell^{TM}$) during storage.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.92-100
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• 1994

Ultrafine cobalt-substituted iron oxide particles were prepared by the thermal decomposition and oxidation of the new organometallic precursor, $Co_xFe_{1-x}(N_2H_3COO)_2(N_2H_4)_2$ (x = 0, 0.01, 0.02, 0.03, 0.05, 0.10, 1.00). The organometallic precursors were synthesized by the reaction of Co(II) and Fe(II) ion in a mole ratio of x : 1-x with hydrazinocarboxylic acid, and characterized by quantitative analysis, elemental analysis and infrared spectroscopy. The mechanistic study on the thermal decomposition of the organometallic precursors was performed by TG-DTG and DSC. The cobalt-substituted iron oxide particles were obtained by the heat treatment of the precursors at $350^{\circ}C$ and $450^{\circ}C$ for six hours in air. The prepared iron oxide was found to have two phases such as ${\gamma}-Fe_2O_3$ and a mixture of ${\gamma}-Fe_2O_3\;and\;{\alpha}-Fe_2O_3$ at $350^{\circ}C$ and $450^{\circ}C$ respectively. The particle shape was equiaxial and the particle size was less than 0.05 ${\mu}m.$ The coercivity and squareness of the cobalt substituted iron oxide particles increased with increasing cobalt content. Both coercivity and squareness showed higher values at $450^{\circ}C.$

• Journal of the Korean Society of Food Science and Nutrition
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• v.16 no.3
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• pp.85-90
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• 1987

This experiment was carried out to study the preparations of red pepper oleoresin, the effects of pH and heat treatment on the stabilities of capsanthin and capsaicin in oleoresin state, and the interacting effects of ascorbic acid, metal salts and EDTA on the stabilities of capsanthin in the oleoresin-linoleate aqueous model system. The results were as follows: 1. Acetone was the most effective solvent to extract capsanthin and capsaicin from red pepper powder. The yield of oleoresin extracted with acetone was 14.27%. 2. Capsaicin was more stable at high temperature than capsanthin in oleoresin state. Capsanthin and capsaicin in oleoresin state were comparatively stable in the range (ron) pH 3 to pH 8. 3. Ascorbic acid acted as a prooxidant on the capsanthin oxidation reaction at concentrations up to $10^{-3}M$, but acted as an antioxidant at $10^{-1}M$. 4. The addition of $Cu^{+2}M$ and $Fe^{+3}M$ ions at all concentration increased the prooxidant activity on the degradation of capsanthin in oleoresin state. 5. EDTA showed a strong antioxidation the stability of capsanthin in oleoresin state.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.98-104
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• 2023

The feasibility of an efficient process proposed for Cu-Cu flip-chip bonding was evaluated by forming a porous Cu layer on Cu pillar and conducting thermo-compression sinter-bonding after the infiltration of a reducing agent. The porous Cu layers on Cu pillars were manufactured through a three-step process of Zn plating-heat treatment-Zn selective etching. The average thickness of the formed porous Cu layer was approximately 2.3 ㎛. The flip-chip bonding was accomplished after infiltrating reducing solvent into porous Cu layer and pre-heating, and the layers were finally conducted into sintered joints through thermo-compression. With reduction behavior of Cu oxides and suppression of additional oxidation by the solvent, the porous Cu layer densified to thickness of approximately 1.1 ㎛ during the thermo-compression, and the Cu-Cu flip-chip bonding was eventually completed. As a result, a shear strength of approximately 11.2 MPa could be achieved after the bonding for 5 min under a pressure of 10 MPa at 300 ℃ in air. Because that was a result of partial bonding by only about 50% of the pillars, it was anticipated that a shear strength of 20 MPa or more could easily be obtained if all the pillars were induced to bond through process optimization.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.3
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• pp.103-107
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• 2024

In this study, nickel, a pure metal material, was proposed as a saggar for synthesizing NCM [Li(Ni_xCo_yMn_z)O₂] cathode active material. Nickel is known as a metal that is resistant to oxidation and has a high melting point. Nickel is one of the main components of NCM cathode material and was expected to be free from problems with contamination from saggar during cathode material synthesis. We sought to confirm the possibility of nickel as a saggar for synthesizing NCM cathode active materials. When a Ni metal crucible and Ni_0.8Co_0.1Mn_0.1(OH)₂ (NCM 811) precursor material were reacted at 900℃ for a long time, the change in the reaction layer on the surface of the crucible over time was analyzed. The nickel crucible reaction layer formed during heat treatment at 900℃ was nickel oxide, and is thought to have been created by simultaneous oxygen diffusion from the cathode precursor oxide and reaction with oxygen in the atmosphere. The change in thickness of the oxide layer appears to slow down after 480 hours, which suggests that the rate of oxygen diffusion from the precursor is reduced. It remained combined without falling out of the crucible until 480 hours. However, it was confirmed that the oxide layer falls off after 720 hours, so it is thought that it can be used as saggar for NCM synthesis only for a certain period of time.

• Korean Chemical Engineering Research
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• v.62 no.3
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• pp.233-237
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• 2024

This study is about the fabrication of a flexible electrode based on PAN-based carbon fibers tow using organic/inorganic nanocomposite and its application of non-enzymatic sensor. The organic/inorganic nanocomposite was composed of the conductive polymer polyaniline (PANI) and the metal oxide CuO. And glucose was used as the target of the electrochemical sensor. Commercialized CFTs were pretreated through heat treatment for desizing and electrochemical oxidation for activation. This nanocomposite was sequentially synthesized on the pretreated CFT surface using electrochemical polymerization and electrochemical deposition. Finally, the CFT/PANI/CuO NPs electrode was obtained. The electrochemical properties and sensing performance of the CFT/PANI/CuO NPs electrode were analyzed using chronoamperometry (CA), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The sensitivity of the CFT/PANI/CuO NPs electrode was about 8.352 mA/mM (in a linear range of 0.445~6.674 mM) and 3.369 mA/mM (in a linear range of 6.674~50 mM), respectively. So, the CFT/PANI/CuO NPs electrode exhibited the enhanced sensing performances due to unique properties such as small peak potential separation, low electron transfer resistance, and large specific surface area.