• 산업과 과학
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• 제2권1호
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• pp.8-14
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• 2023

본 연구에서는 흑마늘 제조 시 발생하는 부산물을 이용하여 기능성 사료 첨가제룰 개발하기 위한 사전 실험으로 수행되었다. 흑마늘박의 항산화 활성과 면역증강 활성을 측정하였으며 흑마늘박의 항산화 활성을 측정한 결과 흑마늘박이 항산화 활성이 있는 것으로 나타났다. 실험에 사용된 시료중 흑마늘박을 포함한 식물성 시료의 면역증강 활성을 실험하기 위해 Nitric oxide(NO) assay 실험을 한 결과 식물성 추출물인 흑마늘박, 섬쑥부쟁이, MIX가 최고 농도에서 LPS(100%)대비 각각 흑마늘박(69.4%), 섬쑥부쟁이(35.9%), MIX(45.3%)의 NO를 생성하였다. 따라서, 흑마늘박이 항염증 효과를 함유하고 있고 흑마늘박과 섬쑥부쟁이의 최적의 혼합비를 선정한다면 항염증 효과를 함유하고 있는 사료 첨가제로써 충분한 가치가 있을 것으로 사료된다.

• Corrosion Science and Technology
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• 제3권1호
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• pp.6-13
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• 2004

The effect of inhibitors on the electrochemical behavior and the stress corrosion cracking resistance of Alloy 600(UNS N06600) was evaluated in 10% sodium hydroxide solution at $315^{\circ}C$. The specimens of a C-ring type for stress corrosion cracking test were polarized at 150 mV above the corrosion potential for 120 hours with and without inhibitors such as titanium oxide, titanium boride and cerium boride. The chemical compositions of the films formed on the crack tip in the C-ring specimens were analyzed using a scanning Auger electron spectroscopy. The cerium boride, the most effective, was observed to decrease the crack propagation rate more than a factor of three compared with that obtained in no inhibitor solution. It was found that the changes of the active-passive transition potentials and the film compositions were related to the resistance to stress corrosion cracking in high temperature caustic solution.

• 한국세라믹학회지
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• 제41권8호
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• pp.605-609
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• 2004

다양한 금속산화물(NiO, MgO, Cr$_2$O$_3$) 첨가에 따른 ZnO 바리스터의 미세구조, 전기적, 유전적 특성을 조사하였다. 평균 결정립 크기는 NiO 첨가로 증가한 반면 Cr$_2$O$_3$ 첨가로 감소하였다 이로 인해 바리스터 전압은Cr$_2$O$_3$ 첨가시 더 높게 나타났다. 바리스터 가운데서 Cr$_2$O$_3$가 첨가된 바리스터가 비직선 지수가 40.5, 누설전류가 2.7 $\mu$A로 가장 우수한 비직선성을 나타내었으며, 유전손실도 0.0589로 비교적 낮게 나타났다.

• 한국초전도ㆍ저온공학회논문지
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• 제5권1호
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• pp.13-16
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• 2003

Adhesion of $SrZrO_3$ resistive oxide barrier on Ag sheathed Bi(2223) tapes prepared by the sol-gel and dip-coating method was evaluated with an aid of Taguchi method and Lie($2^1{\times}3^7$) orthogonal arrays to determine the optimal process combination of levels of factors that best satisfy the bigger is better quality characteristic (QC=B). For analyses of results statistical calculations such as average and analysis of variance (ANOVA) were employed to analyze the results for improving the performance qualities of the dip-coated $SrZrO_3$ film. Experimentally, the performance of the films was evaluated in terms of bond strength by varying Sr/Zr moi ratio (A), amount of organic vehicle additives (B), drying temperature (C) and time (D), heat treatment temperature (E) and time (F), respectively. The optimal combination of levels of factors was determined to be $A_3B_2C_3D_2E_1F_3$ having a 90% confidence level.

• International Journal of Fluid Machinery and Systems
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• 제4권2호
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• pp.223-228
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• 2011

The performance characteristics of centrifugal pump were measured experimentally when running with tap water and drag-reducing surfactant (Octadecyl dimethyl amine oxide (OB-8)) solutions. Tests have been performed on five cases of surfactant solutions with different concentrations (0ppm (tap water), 200ppm, 500ppm, 900ppm and 1500ppm) and four different rotating speeds of pump (1500rpm, 2000rpm, 2500rpm and 2900rpm). Compared with tap water case, the experimental results show that the total pump heads for surfactant solution cases are higher. And the pump efficiency with surfactant solutions also increases, but the shaft power for surfactant solutions cases decreases compared to t hat for tap water. There exists an optimal temperature for surfactant solutions, which maximizes the pump efficiency.

• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.159-169
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• 2005

Cellulose, consisted of 45 wt% in wood, is usable as fuels and heavy oil additives if depolymerized to monomer unit, because the chemical structures are similar to high octane materials found in gasoline. In this study, thermochemical degradation by solvolysis reaction of cellulose such as the effect of reaction temperature, reaction time and type of solvent on conversion yield and degradation products were investigated. It was found that the effectiveness of the solvent on the sovolysis reaction was as follows; acetone>n-butanol>tetralin. When acetone was used as a solvent, the highest cellulose conversion was observed to be 91.8% at 500$^{\circ}C$, 40min. Combustion heating value of liquid products from thermochemical conversion processes was in the range of 7,330${\sim}$7,410cal/g. The energy yield and mass yield in acetone-solvolysis of cellulose was as high as 66.8% and 37.0 g oil/100g raw material after 40min of reaction at 400$^{\circ}C$. Various aliphatic and aromatic compounds were detected in the cellulose solvolysis products. The major components of the solvolysis products, that could be used as fuel, were mesityl oxide, mesitylene, isophorone.

• Elastomers and Composites
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• 제51권3호
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• pp.175-180
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• 2016

Influence of amino acidic chemical on properties of maleic anhydride-grafted ethylene-propylene-diene terpolymer/zinc oxide (EPDM-g-MAH/ZnO) composites was investigated. 4-Aminosalicylic acid (ASA), 4-amino-2-methoxybenzoic acid (AMBA), 12-aminolauric acid (ALA), and glutamine (Gln) were employed as the amino acidic chemicals. Though small quantity (0.5 phr) of the amino acidic chemical was added to the EPDM-g-MAH/ZnO composite, the properties were notably changed. By adding the amino acidic chemical, the percent crystallinity and apparent crosslink density were reduced. Order of the percent crystallinity was related to that of the $pK_a$ values of amino acidic chemicals. By adding the amino acidic chemical, the basic tensile properties were on the whole improved. The experimental results were explained by the $pK_a$ values of amino acidic chemicals, change of zinc ionomer formation, and interactions between the additive and EPDM-g-MAH chain.

• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.924-929
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• 2004

The microstructure, electrical and dielectric characteristics of $ZnO-{Pr}_6{O}_11-{CoO}-{Dy}_2{O}_3$-based varistors were investigated without and with various metal oxide additives(NiO, MgO, Cr$_2$O$_3$). The average grain size decreased in the range of 18.4 $\backsim$ 11.5 $\mu$m, in order of NiO\longrightarrowMgO\longrightarrow{Cr}_2{O}_3$ and the density decreased in the range of 5.62 \backsim 5.33 $g/{cm}^3$ in order of NiO\longrightarrowCr$_2$O$_3$\longrightarrowMgO. While, the nonlinear exponent increased In the range of 19.8$\backsim$67.4 in order of NiO\longrightarrowMgO\longrightarrow${Cr}_2{O}_3$ and the leakage current decreased in the range of 25.6 $\backsim$ 1.2 $\mu$A in order of NiO\longrightarrow${Cr}_2{O}_3$\longrightarrowMgO. Among all varistors, the Cr$_2$O$_3$-added varistor exhibited the highest nonlinearity, with a nonlinear exponent of 67.4 and a leakage current of 1.2 $\mu$A. Furthermore, this varistor exhibited the lowest dielectric dissipation factor of 0.0407.

• Tribology and Lubricants
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• 제11권5호
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• pp.136-143
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• 1995

The effect of additive chemistry on the serface fatigue of gears was investigated using the FZG gear tester and fluids based on an API GL-5 grade oil. Surface fatigue lives were determined as a function of load and additive chemistry. At 1.52 GPa, the removal of the primary extreme pressure additive (EP) from the fully formulated gear oil decreased the fatigue life of gears slightly (4%), however, the removal of the primary antiwear additive (AW) decreased the fatigue life of gears significantly (83%). At 1.86 GPa, the removal of the EP additive from the fully formulated gear oil decresed the gear fatigue life 27%, however, the removal of the primary AW additive decreased the fatigue life of gears significantly (75%). Micropitting was the dominant surface morphology in the dedendum of gears tested With two oils at load stage: one using the complete additive package, and a second where the EP additive has been removed. However, spalling is the primary failure mode of gears tested without an AW additive independent of whether an EP agent was present. Surface analysis of pinion gears showed the formation of a mixed phosphate/phosphite-oxide layer on the surface of gears tested with fluids containing an AW. Formation of this layer seems to be key to long fatigue life.

• Fisheries and Aquatic Sciences
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• 제13권1호
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• pp.18-25
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• 2010

Interest in plant-derived food additives has increased recently, with efforts to identify natural antioxidant sources to replace synthetic antioxidants. This study evaluated the antioxidant effects of organic solvent fractions of 80% methanol extracts from Pediastrum duplex and Dactylococcopsis fascicularis microalgae. Among the solvent fractions tested, the ethyl acetate and n-hexane fractions from P duplex effectively scavenged 79.8% and 74.5% of DPPH free radicals, respectively. The chloroform fraction from D. fascicularis showed the strongest $H_2O_2$ scavenging ability (49.7%). The greatest scavenging of hydroxyl radicals (73.1%) was exhibited by the 80% methanol extract from P duplex. Aqueous residue and ethyl acetate fraction from P duplex provided the strongest nitric oxide scavenging (57.7%) and metal chelating effect (82.1%), respectively. Chloroform and ethyl acetate fractions from P duplex and n-hexane fraction from D. fascicularis exhibited significantly greater inhibition of lipid peroxidation than the commercial antioxidants. These results suggested that P duplex and D. fascicularis microalgae having potential anti oxidative compounds with various properties could be utilized in the food and pharmaceutical industries.