• 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.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.632-637
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• 2017

The vehicle lubricant occupies upto 35% in a total lubricant market and engine oil occupies upto 77% in the vehicle lubricant market in Korea. A suitable quality management of the circulating engine oil is necessary for driver and engine protection. But, KS and synthetic engine oil products (involved over 30% synthetic oil) are exempt to any quality management under Petroleum and Alternative Fuel Business Act. It is also known that synthetic oils such as PAO (poly alpha olefin) have excellent properties and performance like anti-wear, varnish control and oxidation stability than those of mineral oils. For this reason, PAO has been used for an engine oil, rotary screw and reciprocating compressor in addition to heavy duty and other extreme service applications. In this study, our research group analyzed the chromatogram pattern for the mineral oil, PAO and mineral oil involved a typical ratio of PAO using SIMDIST (simulated distillation). In the SIMDIST chromatogram, the mineral oil showed a broad peak, while PAO showed a sharp typical peak. Also the oil with a large viscosity grade exhibited a long retention time due to the heavy molecular weight and high boiling point. In particular, the blended mineral oil with 20% PAO sample showed a distinctly different pattern compared to that of using the conventional mineral oil. For monitoring PAO contents in distributing engine oils, we analyzed the SIMDIST for 27 kinds of engine oils which were popularly sold in Korea. The analytic results indicate that all kinds of engine oils showed that PAO contents were below 20% in engine oil products. Moreover, the PAO titled product was found to have a small amount of PAO. Thus, we conclude that the related laws for the proper quality management of synthetic oils are needed to be established.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.514-520
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• 2021

In this study, EMP shielding performance was evaluated using electric furnace oxidized slag to give EMP shielding performance to concrete among the most used materials in construction sites. As a result of the evaluation, the component of the electric furnace oxidation slag was found to have an Fe₂O₃ content of 34%, and it was also found to contain an MgO component of about 4.8%. In addition, as a result of conducting an aggregate stability evaluation due to concerns about expansion due to MgO components, it is considered to be suitable for the KS standard. EMP shielding performance evaluation result showed that there was no correlation in EMP shielding performance according to compressive strength, and that general aggregates did not have EMP shielding. However, it was found that the aggregate using the furnace oxidized slag had excellent EMP shielding performance, and the shielding performance improved as the thickness increased. As a result of the durability evaluation, it was found that the EMP shielding concrete has the durability of abortion compared to the general concrete. Through this, it is thought that it will be good to improve the shielding rate if concrete is manufactured using electric furnace oxide slag when constructing EMP shielding structures in the future.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.228-236
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• 1996

An electrolysis system with a vertically circulating mercury capillary bundle electrode was developed with a very large electrode area in a minimum space. This system was operated by forcedly feeding mercury and aqueous solution containing metal ion into a fiber bundle packed densely within a small porous glass tube. In order to test the characteristics and stability of the electrolysis system, the reduction voltammograms of uranyl and ferric ions were measured with changes of the mercury flow rate and the aqueous flow rate. The aqueous flow rate had a large effect on the electrochemical reaction of metal ion occurring at the interface between the mercury and the aqueous solution and had to be regulated as an appropriate value to have a good limiting current shape. The limiting current was linearly proportional to the aqueous flow rate, and complete reductions of uranyl and ferric ions were rapidly and continuously accomplished at the potential showing limiting current. With a mercury flow rate high enough to keep a capillary continuum of mercury in the fiber bundle, the mercury flow rate had almost no effect on the electrochemical reaction. This system was confirmed to be effective and stable enough to control rapidly and continuously the oxidation state of metal ions fed into the system under an appropriate aqueous flow rate.