• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5452-5457
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• 2015

Conjugating a phytochemical, a strong antioxidant, with a functional peptide not only compensates for its stability, but also improves its solubility and anti-wrinkle effects, thereby contributing to the possibility of becoming an excellent cosmetic ingredient. Thus, in this study we examined the potential cosmetic use of a phytochemical-peptide derivative using gallic acid, a phytochemical with antioxidant, anti-inflammatory, and anti-cancer effects. To evaluate the antioxidant and wrinkle-improving efficacy of 5 synthesized gallic acids conjugated with LVH, IVH, KTTKS, YGGFM, and YGGFLRKYP respectively, we observed the expression of genes related to wrinkle improvement using DPPH radical scavenging activity and real-time PCR. As a result, all 5 derivatives had excellent free radical scavenging effects. The expression level of genes involved collagen synthesis also increased, and the secreted peptides during collagen production contributed to their antioxidant and wrinkle improving effects. These results mark the potential use of gallic acid peptide derivatives as a cosmetic ingredient for anti-oxidation and wrinkle improvement.

• Journal of the Korean GEO-environmental Society
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• v.22 no.2
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• pp.15-23
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• 2021

A method of improving the post-management end system of a landfill that reflected total pollutant load was applied to the SUDOKWON 1st Landfill Site. Modeling results showed that the ratio of remaining methane, when compared to the total maximum potential of 2,521 × 106 Nm3, was estimated to be 8.8% in 2020, 7.0% in 2030, and 6.5% in 2040. If the average oxidation rate of 89.1% in 2005-2019 was applied, the ratio decreased by 1.01% in 2020, 0.76% in 2030, and 0.70% in 2040. This suggests that if the amount of methane generated is all emitted from the surface of the landfill after 2025, the real amount emitted to the atmosphere is less than that in 2019; therefore, the post-management end is possible. According to the results of trend analysis of the quality of leachate water, effluent criteria for Biochemical Oxygen Demand (BOD) can be satisfied in 2024, while those for Chemical Oxygen Demand (COD) and Total Nitrogen (T-N) can be satisfied in 2047 and 2117, respectively. If the post-management end system changed based on total pollutant load, the post-management can be terminated BOD today and COD within a few years; however, the fact that T-N could be terminated only after 2041 shows the need to fundamentally change management methods.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.406-406
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• 2016

To get high efficiency n-type crystalline silicon solar cells, passivation is one of the key factor. Tunnel oxide (SiO2) reduce surface recombination as a passivation layer and it does not constrict the majority carrier flow. In this work, the passivation quality enhanced by different chemical solution such as HNO3, H2SO4:H2O2 and DI-water to make thin tunnel oxide layer on n-type crystalline silicon wafer and changes of characteristics by subsequent annealing process and firing process after phosphorus doped amorphous silicon (a-Si:H) deposition. The tunneling of carrier through oxide layer is checked through I-V measurement when the voltage is from -1 V to 1 V and interface state density also be calculated about $1{\times}1012cm-2eV-1$ using MIS (Metal-Insulator-Semiconductor) structure . Tunnel oxide produced by 68 wt% HNO3 for 5 min on $100^{\circ}C$, H2SO4:H2O2 for 5 min on $100^{\circ}C$ and DI-water for 60 min on $95^{\circ}C$. The oxide layer is measured thickness about 1.4~2.2 nm by spectral ellipsometry (SE) and properties as passivation layer by QSSPC (Quasi-Steady-state Photo Conductance). Tunnel oxide layer is capped with phosphorus doped amorphous silicon on both sides and additional annealing process improve lifetime from $3.25{\mu}s$ to $397{\mu}s$ and implied Voc from 544 mV to 690 mV after P-doped a-Si deposition, respectively. It will be expected that amorphous silicon is changed to poly silicon phase. Furthermore, lifetime and implied Voc were recovered by forming gas annealing (FGA) after firing process from $192{\mu}s$ to $786{\mu}s$. It is shown that the tunnel oxide layer is thermally stable.

• Food Science and Preservation
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• v.30 no.2
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• pp.334-346
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• 2023

The antioxidant ability of 80% ethanolic extract of nutmeg seed (NM80) was evaluated using in vitro assays and bulk oil and oil-in-water (O/W) emulsion matrices. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) cation radical scavenging, and oxygen radical antioxidant capacity (ORAC) in vitro assays were used to evaluate the antioxidant ability of the extract. The DPPH radical scavenging activities of 25, 50, 100, and 200 ㎍/mL NM80 were 12.5, 20.9, 35.1, and 62.8%, respectively, while the ABTS cation radical scavenging activities were 2.7, 6.5, 30.5, and 29.8%, respectively, demonstrating a dose-dependent effect. The ORAC value was significantly higher at an NM80 concentration of 25 ㎍/mL than the positive control (p<0.05). The conjugated dienoic acid (CDA), ρ-anisidine, and tertiary butyl alcohol values in 90-min-heated corn oil containing 200 ppm of NM80 were significantly reduced by 3.26, 16.94, and 17.34%, respectively, compared to those for the sample without NM80 (p<0.05). However, the headspace oxygen content and CDA value in the O/W emulsion containing 200 ppm of NM80 at 60℃ had 6.29 and 82.85% lower values, respectively, than those for the sample without NM80 (p<0.05). The major volatile compounds of NM80 were allyl phenoxyacetate, eugenol acetate, and eugenol. NM80 could be an effective natural antioxidant in lipid-rich foods in bulk oil or O/W emulsion matrix.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.459-463
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• 2017

Hot dip galvanizing in the steel plant is one of the most widely used methods for preventing the corrosion of steel materials including structures, steel sheets, and materials for industrial facilities. While hot dip galvanizing has the advantage of stability and economic feasibility, it has difficulty in repairing equipment and maintaining the facilities due to high-temperature oxidation caused by Zn Fume where molten zinc used in the open spaces. Currently, SM45C (carbon steel plate for mechanical structure, KS standard) is used for the equipment. If a part of the equipment is resistant to high temperature and Zn fume, it is expected to improve equipment life and performance. In this study, the manufactured Ni alloy was tested for its corrosion resistance against Zn fume when it was used in the hot dip galvanizing equipment in the steel plant. Two kinds of materials currently used in the equipment, new Ni alloy and Inconel(typical corrosion-resistant Ni alloy), were selected as the reference groups. Two kinds of molten metal were used to confirm the corrosion of each alloy according to the molten metal. Zn fume was generated by bubbling Ar gas from molten Zn in a furnace($500{\sim}700^{\circ}C$) and the samples were analyzed after 30 days. After 30 days, the specimens were taken out, the oxide layer on the surface was confirmed with an optical microscope and SEM, and the corrosion was confirmed using a potentiodynamic polarization test. Corrosion depends on the type of molten metal.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.35-48
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• 2013

Biodiesel is an alternative diesel fuel which can be obtained from the transesterification of vegetable oils, animal fats and waste cooking oil. The objective of this study is to evaluate the properties of biodiesel obtained from different feedstocks (soybean, waste cooking, rapeseed, cottonseed and palm oils). The biodiesel derived from different feedstocks was analyzed for FAME (fatty acid methyl esther) content, kinematic viscosity, flash point, CFPP (cold filter plugging point) and glycerin content. The quality of biodiesel was tested according to the Korean and European standard (EN14214, requirements and test method for biodiesel fuel). The biodiesels derived from soybean, waste cooking, rapeseed and cottonseed oils contain high amount of unsaturated fatty acid, while palm biodiesel is dominated by saturated fatty acid. The fuel properties of biodiesel, such as low temperature performance, kinematic viscosity and oxidation stability are correlated with the FAME composition components in biodiesel.

• Korean Journal of Food Science and Technology
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• v.27 no.2
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• pp.205-209
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• 1995

Edible hardened soybean oil is processed by hydrogenation of refined soybean oil in order to upgrade the heat and oxidation stability and to improve flavor and physical nature. This study aims to investigate the influences of various reaction conditions on iodine value, fatty acid composition and trans isomer formation in hydrogenating soybean oil. In case that hardening temperature is $180^{\circ}C$, trans acid formation increased by 6.2 times more under $3.0{\;}kg/cm^{2}H_{2}$ than under $0.5{\;}kg/cm^{2}H_{2}$, while linolenic acid decreased in contents. In case of $200^{\circ}C$ of hardening temperature trans acid formation showed 4.6% higher under $0.5{\;}kg/cm^{2}H_{2}$ than under $3.0{\;}kg/cm^{2}H_{2}$ while contents of linolenic and linoleic acids showed 0.51% and 2.5% lower respectively. It is concluded that $200^{\circ}C$ of hardening temperature under 0.5 and $3.0{\;}kg/cm^{2}H_{2}$ is better condition because trans isomers are little produced, and iodine value and linolenic acid content decreased in hardening soybean oil.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.5
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• pp.734-737
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• 2005

This study was conducted to determine the effect of effective microorganism (EM) treatment in feeding system of swine on carcass characteristics. EM pork, which reared with EM additives and EM activated liquids, and conventional pork (non-EM pork) were stored at $4^{\circ}C$. Chemical composition and storage stability of EM pork were compared with conventional pork. Cholesterol content at EM pork was 71 mg/100 g, which is lower than that of conventional pork (83 mg/100 g) when the meats were stored at $4^{\circ}C$ refrigerator. And EM pork (0.165 MDA mg/kg) showed higher antioxidant effect than control pork (0.184 MDA mg/kg). And also protein denaturalization at EM pork showed lower rate $(3.19\;mg\%)$ than that of conventional pork $(4.9\;mg\%)$ when the meats were stored at $4^{\circ}C$ refrigerator, showing that inhibitory effect of protein denaturalization was increased up to $35\%$ over the conventional pork. These results show that the EM pork had superior traits in terms of cholesterol level, lipid oxidation and protein denaturalization to the conventional pork.

• Journal of the Korean Chemical Society
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• v.40 no.7
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• pp.467-473
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• 1996

Although a polypyrrole shows better electrical conductivity, 100∼400 ${\Omega}^{-1}cm^{-1}$, than other organic conducting polymers, its electrical conductivity will be worsen in the presence of the oxygen due to its easy oxidation. On the other hand, polythiophene shows better stability in the air while its electrcal conductivity is poor compared to the polypyrrole. We succeed to develope the mixed polymer electrode that is stable in the air and shows a good redox characteristics. The mixed polymer electrode has been prepared by the electrical polymerization of polypyrrole on the Pt electrode as 1.70 C$cm^{-2}$ and then coating with polythiophene as 0.34 C$cm^{-2}$. The polymerization rate of polythiophene was $3.89{\times}10^{-8}$ at the bare Pt electrode and $6.07{\times}10^{-8}cms^{-1}$ at the mixed polymer electrode. And the standard rate constants of each electrode were $5.16{\times}10^{-6}\;and\;3.94{\times}10^{-4} cms^{-1}$ respectively. Also, the electrocatalytic rate of the polypyrrole polymer electrode was $3.45{\times}10^{-3}cm^3mol^{-1}s^{-1}.$ We found the immobilized layer at the modified electrode acted as an electrocatalyst. Finally, this polymerization process at the Pt electrode was the electron transfer controlled, but that the mixed polymer electrode was the diffusion and charge transfer controlled.

• Journal of the Korean Chemical Society
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• v.38 no.11
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• pp.785-791
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• 1994

The $Sr_1-_xY_xMnO_3$ (x = 0.0∼1.0) system was synthesized using amorphous citrate process. The stability of various structures and the electronic transport properties of this system were investigated. X-ray diffraction study indicated that the $Sr_1-_xY_xMnO_3$ system has three different structures depending on composition, namely, 4L-hexagonal perovskite (when x is less than 0.3), pseudocubic perovskite (when x is 0.3∼0.7), and hexagonal nonperovskite (when x is larger than 0.7) structures. The structural changes and electronic properties were interpreted based on two factors, i.e., the size of cations and the oxidation state of manganese ion. When the concentration of Y substitution exceeds 30%, the Mn-Mn repulsive interaction dominates over intermetallic attraction, and thus structure changes to pseudocubic perovskite. In perovskite phase the unit cell dimensions increases with increasing $Mn^{3+}$ ions due to yttrium substitution. The band gap of $Sr_{0.9}Y_{0.1}MnO_3$ is greater than that of $Sr_{0.5}Y_{0.5}MnO_3$. The greater band gap of $Sr_{0.9}Y_{0.1}MnO_3$ indicates that the 4L-hexagonal structure is more stabilized than cubic perovskite due to the Mn-Mn bond.