• 한국자동차공학회논문집
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• 제6권3호
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• pp.138-142
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• 1998

Among aftertreatment devices which reduce exhaust gas of diesel engine, diesel oxidation catalyst(DOC) with high reduction efficiency for gaseous matter and particulate matter is now being studied actively. In this study, an experiment was conducted to analyze the effects of low sulfur diesel fuel in heavy duty diesel engine equipped with DOC. We tested to estimate change of engine performance for the low and high sulfur diesel fuels in a 11,000cc diesel engine equipped with DOC. We conducted test to estimate the reduction efficiency of exhaust gas in D-13 mode of heavy duty diesel regulation mode and in smoke opacity mode for two samples of high sulfur content (0.2%) and low sulfur content(0.05%)

• 한국식품조리과학회지
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• 제9권2호
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• pp.88-93
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• 1993

Semi-prepared frozen muscle foods purchased from local industry were tested for lipid oxidation. The effects of various storage conditions, cooking methods, defrosting methods and reheating methods on rancidity were examined using TBA assay and sensory evaluation. TBARS values were increased faster in cooked samples than in uncooked ones during storage periods. During refrigeration of cooked samples, TBARS values were increased significantly for 15 days (p<0.001). In defrosting experiments, refrigerated defrosting was proven to be better compared with room temperature or microwave defrosting (p<0.05). For overall explanation, stepwise regression analysis was done and the results are in this order: storage conditions, cooking methods, moisture content, and lipid content. Using these 4 variables, TBARS values could be explained by 40~53%.

• 한국세라믹학회지
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• 제27권6호
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• pp.817-823
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• 1990

Pilot-scale experiments on the oxidation of TiCl4 to produce TiO2 were carried out in a verical reactor of 20cm in inside diameter and 140cm in length ; LPG burning was used as a heating means to maintain the reaciton temperature. The effects of reaction temperature and excess oxygen content on the conversion of TiCl4 and on the particle size of produced TiO2 were investigated. The ranges of operating conditions varied were 900 to TiO2 was 0.45-0.57${\mu}{\textrm}{m}$, TiCl4 conversion was 82-96%, the rutile content was 33-57% and the contents of impurities were 0.03% of Fe, 0.03% of SiO2 and 62ppm of Cl. These experimental results were compared with those of other investigators.

• 펄프종이기술
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• 제43권1호
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• pp.23-28
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• 2011

The pine wood meal was ozonated in acidic water. A 91.3% of lignin and 13% of polysaccharides in pine wood meal were degraded with 180 min ozonation. The phenolic hydroxyl groups of lignin in ozonated wood meals were increased with ozonation time. The vanillin content in nitrobenzene oxidation products of lignin is decreased with 10 min. ozonation and it was slightly increased with ozonation time. The sugar composition of ozonated wood meals showed that the hemicellulose was more susceptible to ozonation than cellulose. The crystallinity of ozonated wood meal was increased.

• 한국환경과학회지
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• 제11권1호
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• pp.85-91
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• 2002

The effects of initial concentration of dissolved oxygen content, Cu(II) and EDTA in an aqueous Cu(II)-EDTA solution on $TiO_2$ photo-oxidation of EDTA were investigated using $TiO_2$ (Degussa P-25) and UV irradiation at $20{\circ}C$. In the presence of dissolved oxygen and/or Cu(II) the photo-oxidation rates of EDTA were enhanced. The rates linearly increased in the range of initial Cu(II) concentration below 1.79 mM, while abode this concentration those were kept constant. The trend or the EDTA photo-oxidation rates appeared to be akin to the Langmuir-Hinshelwood equation farm and the k values calculated were 0.05 mM/min for the free-EDTA system, and 0.17 mM/min far the Cu(II)-EDTA system. These meant the aqueous EDTA decomposition was enhanced due to weakening of the intra-molecular bond strength of EDTA by complexation with Cu(II) added. It was concluded the decomposition of aqueous EDTA by $TiO_2$ photo-oxidation was maximum in the presence of dissolved oxygen supplied by air purging and of Cu(II) with its concentration for 1:1 Cu(II)-EDTA complexation ratio.

• Tribology and Lubricants
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• 제34권4호
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• pp.160-167
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• 2018

Vegetable oils can contribute to the goal of energy independence and security owing to their naturally renewable resources. One of the representative vegetable oils is biodiesel, which is being used in domestic and European markets as a blended fuel with automotive diesel. Vegetable oils are promising candidates as base fluids to replace petroleum lubricants because of their excellent lubricity and biodegradability. We prepared biodiesel with a purity of 99.9% via the esterification of waste cooking oil. Blended biodiesel and Petro-lube base oil were mixed to produce five types of mixed lubricating oil. We analyzed the various characteristics of the blended biodiesel with Petro-lube base oil for different blending ratios. The lubricity of the vegetable lubricant improves as the content of biodiesel increases. In addition, since zinc dialkyldithiophosphates (ZnDTPs) are widely used as multifunctional additives in petroleum-based lubricants, we optimized the blending ratio for lubricity, oxidation stability, and shear stability by adding ZnDTP as a performance additive to improve the biodiesel properties, such as oxidation stability and hydrolysis. The optimized lubricants improve by approximately 25% in lubricity and by 20 times in oxidation stability and shear stability after the addition of ZnDTP.

• 한국수산과학회지
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• 제27권2호
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• pp.155-165
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• 1994

To evaluate the antioxidant effect of flavonoids and a-tocopherol on purified fish oil(up to $40\%$ of n-3 polyunsaturated fatty acids), lipid peroxidation, and fatty acids content during storage and upon heating were determined. The potential of these compounds for inhibiting and delaying both oxidation and lipoxygenase processes was also evaluated. The oxidation of fish oil was effectively inhibited by flavonoids and a-tocopherol. The antioxidizing effect of these compounds increased in proportion to their concentration. The addition of a-tocopherol and catechin-a-tocopherol mixture were prolonged induction period of lipid oxidation by 3.5 to 4 times. All other flavonoids also shown more than twice the prolonging effect. Lipoxygenase activity was decreased by catechin and a-tocopherol effectively.

• Corrosion Science and Technology
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• 제2권3호
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• pp.148-154
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• 2003

The addition of Ni leads to the formation of protective rust layer on steel and subsequently high corrosion resistance of steel in $Cl^-$-containing environment. $\alpha$-FeOOH, $\beta$-FeOOH, $\gamma$-FeOOH and $Fe_3O_4$ are formed mainly on steels exposed to $Cl^-$-containing environment. As the first work of this kind, this study reports the influence of Ni on the oxidation behavior of $Ni_xFe_{1-x}(OH)_2$ in $Cl^-$-containing solution at two different pH regions(condition I under which the solution pH is allowed to decrease and condition I under which solution pH is maintained at 8) where $\gamma$-FeOOH and $Fe_3O_4$ are predominantly formed, respectively, upon oxidation of $Fe(OH)_2$, In the presence of Ni(II) in the starting solution, the formation of $\beta$-FeOOH was facilitated and the formation of $\gamma$-FeOOH was suppressed with increasing Ni(II) content and with increasing oxidation rate of Fe(II). Ni(II) was found to have $Fe_3O_4$-suppressing effect under condition II.

• Food Science and Biotechnology
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• 제18권3호
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• pp.604-609
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• 2009

The antioxidative activities of the water solution of crude extract from edible mushroom enokitake Flammulina velutipes were compared with those of ascorbic acid and ascorbic acid 6-palmitate in oil-in-water (O/W) emulsions of cod liver oil. Oxidation of the emulsions was carried out at 40 and $50^{\circ}C$ in the dark. The antioxidant activities were measured by in vitro assay against oxygen uptake, 2-thiobarbituric acid value, hydroperoxide formation of the oils. Also, residual docosahexaenoic acid content was measured as indices of lipid oxidation. The cod liver oil in O/W emulsions with added enokitake crude extract (ECE) was significantly more stable against lipid oxidation than the control emulsions without the extract in terms of any oxidation indices used. Moreover, ECE provided remarkable antioxidative properties to eicosapentaenoic acid ethyl ester in emulsion system. These observations demonstrate that F. velutipes can be used as a natural antioxidant, which effectively prevents oxidation of polyunsaturated oils in emulsion system.

• 한국세라믹학회지
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• 제37권1호
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• pp.96-101
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• 2000

Comparative studies on microstructure, and mechanical and anti-oxidation properties between TiN and Ti-Si-N films were performed. The Ti-Si-N films were deposited on high-speed steel and silicon wafer substrates by plasma-assisted chemcial vapor deposition(PACVD) technique. The Si addition to TiN film caused to change the microstructure such as grain size refinement, randomly multi-oriented microstructure, and nano-sized codeposition of silicon nitride in the TiN matrix. The Ti-Si-N film, contains Si content of ∼7 at.%, showed the micro-hardness value of ∼3400 HK, which was higher than the pure TiN film whose hardness was ∼1500HK. The Ti-Si(7 at.%)-N film also showed much improved anti-oxidation properties compared with those of the pure TiN film. These properties were also related to the microstructure of Ti-Si(7 at.%)-N film was formed and retarded further oxidation of the nitridelayer. These properties were also related to the microstructure of Ti-Si(7 at.%)-N film which was characterized by nano-sized precipitates of silicon nitride phase in the TiN matrix and randomly oriented grains.