• Progress in Superconductivity
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• v.8 no.1
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• pp.59-64
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• 2006

High $J_c\;YBa_2Cu_3O_x$ superconducting films were fabricated by MOD method using fluorine-free dichloroacetic acid(DCA) as chelating solvent for preparing precursor solution. Coating solutions were prepared by dissolving Y-, Ba- and Cu-acetates in DCA solvent followed by drying in rota vapor to obtain the blue gel that is diluted in methanol and 2-methoxyethanol for adjusting the cation concentration. DCA-MOD precursor solution was coated on a single crystal(001) $LaAlO_3(LAO)$ substrate by a dip coating method with a speed of 25 mm/min. Coated films were calcined at lower temperature up to $500^{\circ}C$ in flowing oxygen atmosphere with a 7.2% humidity. Conversion heat treatment was performed at various temperatures of $780{\sim}810^{\circ}C$ for 2 h in flowing Ar gas containing 1000 ppm oxygen with a humidity of 9.45%. SEM observations showed that films have very dense microstructures for the films prepared at the temperature higher than $800^{\circ}C$ regardless of diluting solvent; methanol or 2-methoxyethanol. X-ray diffraction analysis showed that YBCO grains grew with a (001) preferred orientation. A High critical current density($J_c$) of 1.28 $MA/cm^2$(@77 K and self-field) was obtained id. the YBCO film prepared using 2-methoxyethanol as a solvent.

• Journal of Powder Materials
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• v.8 no.3
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• pp.163-167
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• 2001

A bulk porous $CaZrO_3/MgO$ composite with plantinum nano-dispersion was synthesized in air atmosphere through the combination of several in situ reactions, including the pyrolysis of $PtO_2$. A mixture of $CaMg(CO_3)_2$(dolomite), $ZrO_2$, $PtO_2$ and LiF (0.5 wt%, as an additive) was cold isostatically pressed at 200 MPa and sintered at $1100^{\circ}C$ for 2 h. The porous $CaZrO_3/MgO/Pt$ composite ($CaZrO_3/MgO$ : Pt=99 : 1 in volume) had a uniformly open-porous structure (porosity: 56%) with three-dimensional (3-D) network and a narrow pore-size distribution, similarly to the porous $CaZrO_3/MgO$ composites reported before. Catalytic Properties (viz., NO direct decomposition and NO reduction by $C_2H_4$) of the $CaZrO_3/MgO/Pt$ composite were investigated up to $900^{\circ}C$. In the absence of oxygen, the NO conversion rate reached ~52% for the direct decomposition and ~100% for the reduction by $C_2H_4$, respectively. The results suggest the possibility of the porous composite as a multifunctional filter, i.e., simultaneous hot gas-filtering and $de-NO_x$ in one component.

• Korean Journal of Pharmacognosy
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• v.26 no.4
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• pp.355-359
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• 1995

To find serotonin(5-hydroxytryptamine, 5-HT)-antagonizing activities in traditional herbal drugs, crude extracts from 66 kinds of traditional herbal drugs were randomly screened for inhibitory effects on 5-hydroxytryptophan(HTP)-induced diarrhea in mice. Intraperitoneal injection of 5-HTP(2.5 mg/kg) induced diarrhea in 92% of mice, when observed from 10 to 15 min after injection. Crude extracts(2 g/kg) from 66 kinds of traditional herbal drugs were orally pretreated for 1 h before 5-HTP injection. Of the 66 herbal drugs screened, Ephedrae Herba(麻黃), Cimicifugae Rhizoma(升麻), Anisi stellati Fructus(八角茴香), Aurantii Fructus(枳實), Polygalae Radix(遠志) showed the most potent inhibiting activities against 5-HTP(2.5 mg/kg)-induced diarrhea in mice. There are at least 3 possible mechanisms that would be responsible for the inhibitory effect of crude extracts on 5-HTP-induced diarrhea; 1) crude extract-induced inhibition of the activity of aromatic aminoacid decarboxylase catalyzing the conversion of 5-HTP to 5-HT, 2) crude extract-induced blockade of 5-HT receptor(s) in the gastrointestinal tract responsible for 5-HTP-induced diarrhea, 3) crude extract-induced inhibition of gastrointestinal activity, irrespective of 5-HT system. The exact mechanisms and molecules, responsible for the inhibitory effect of crude extracts on 5-HTP-induced diarrhea remain to be clarified.

• Journal of the Korea Organic Resources Recycling Association
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• v.6 no.1
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• pp.21-30
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• 1998

The effects of compost inoculation on the degradation of cellulosic fraction in composting of food waste and paper mixture were investigated by bench-scale composting. With the increase of seed inoculation, the time to reach the peaks of temperature, $CO_2$ evolution rate, and ammonia evolution rate was reduced, indicating that seed compost had beneficial effects on the enhanced degradation of organic materials at the early stage of composting. However, the final conversion of organic matters and the loss of ammonia were not affected by the amount of seed compost inoculated. The increasing of seed inoculum also resulted in the higher level of cellulase activity at initial stages and rapid rise to the maximums, suggesting that initial supply of sufficient cellulolytic microorganisms might facilitate the evolution of cellulase activity. The cellulose was degraded substantially during the increasing phase of cellulase activity, while they showed similar values at the end of 20 days composting. As a result, the seed inoculation seemed to be effective to the enhanced evolution of cellulase activity and cellulose degradation at initial stage of composting. But it did not contribute to increase the final degradation of cellulose after the entire composting reaction of 20 days.

• Biomolecules & Therapeutics
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• v.17 no.4
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• pp.455-460
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• 2009

Foods of plant origin, especially fruits and vegetables, have attracted attention because of their potential benefits to human health. In this report, Rubi Fructus (RF), the dried unripe fruit of Rubus coreanus Miq (Rosaceae) and ellagic acid (EA) purified from RF were used to test their potential hepatoprotective effect against acetaminophen (AAP)-induced hepatotoxicity in rats. RF extract (RFext) and EA reduced the elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) in serum and the content of lipid peroxide in liver by AAP administration, while the increment of the cellular glutathione (GSH) content and the induction of glutathione S-transferase (GST) and glutathione peroxidase (GSH-PX) which were decreased by AAP administration. RFext and EA from RFext did not affect the two major form of cytochrome P450s, cytochrome P450 2E1 (CYP2E1) and cytochrome P450 1A2 (CYP1A2), but downregulated the cytochrome P450 3A4 (CYP3A4) related to the conversion of AAP to N-acetyl-P-benzoquinone imine (NAPQI). These results suggest that RFext and EA from RF exhibit a hepatoprotective effect not only by increasing antioxidant activities but also by down-regulating CYP3A4 in the AAP-intoxicated rat.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.80-87
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• 2010

Lignite of low rank coal and petroleum coke of high sulfur content can be high potential energy sources for coal gasification process because of their plentiful supply. The kinetic study of steam gasification has been performed in an atmospheric thermobalance with wood chip, lignite, bituminous, anthracite, pet-coke. The effects of gasification temperature($600{\sim}850^{\circ}C$) and partial pressure of steam(30~90 kPa) on the gasification rate have been investigated. The modified volumetric reaction model was applied to the experimental data to describe the behavior of carbon conversion and to evaluate the needed kinetic parameters. Lignite and wood chip with high volatile content showed high average gasification rates comparing to other fuel and thus they might be proper fuel for gasification processes. The activation energies for wood chip, lignite, bituminous, anthracite, and pet-coke through Arrhenius plot were found to be 260.3, 167.9, 134.6, 82.2, 168.9 kJ/mol, respectively. The expression of apparent reaction rates for steam gasification of various chars have been proposed as basic information for the design of coal gasification processes.

• KSBB Journal
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• v.18 no.1
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• pp.8-13
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• 2003

Recombinant trehalose synthase from Thermus caldophilus GK24 showed an ability to produce trehalose from maltose. The activity of the partially purified enzyme was not influenced by most metal ions at 1 mM but was inhibited by 10 mM $Co^{2+}$, $Mn^{2+}$, and $Fe^{2+}$. Enzyme activity varied during prolonged reaction due to changes in the environmental conditions. Thus, the reaction was carried out for an extended time with optimized conditions of $45^{\circ}C$ and pH 7.0. An yield of 32.9% was reached at $60^{\circ}C$ after reaction for 22 h, and, maximum trehalose conversion (69.2%) was attained at $25^{\circ}C$. The yields obtained using enzyme dosages of 10, 25, and 50 U/g were 62.3, 62.3 and 59.0 %, respectively, though the initial conversion rate was higher when the higher dose was used. Similar profiles of trehalose production yields were observed with reaction working volumes of 10 ml to 2,000 ml.

• Clean Technology
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• v.27 no.1
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• pp.69-78
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• 2021

Vegetable oils, such as palm oil and cashew nut shell liquid (CNSL), are used as major raw materials for bio-diesel in transportation and bio-heavy oil in power generation in South Korea. However, due to the high unsaturation degree caused by hydrocarbon double bonds and a high content of oxygen originating from the presence of carboxylic acid, the range of applications as fuel oil is limited. In this study, hydrotreating to saturate unsaturated hydrocarbons and remove oxygen in mixed bio-oil containing 1/1 v/v% palm oil and CNSL on monometallic catalysts (Ni and Cu) and bimetallic catalysts (Ni-Zn, Ni-Fe, Ni-Cu Ni-Co, Ni-Pd, and Ni-Pt) was perform under mild conditions (T = 250 ~ 400 ℃, P = 5 ~ 80 bar and LHSV = 1 h-1). The addition of noble metals and transition metals to Ni showed synergistic effects to improve both hydrogenation (HYD) and hydrodeoxygenation (HDO) activities. The most promising catalyst was Ni-Cu/��-Al2O3, and in the wide range of the Ni/Cu atomic ratio of 9/1~1/4, the conversion for HYD and HDO reactions of the catalysts were 90-93% and 95-99%, respectively. The tendency to exhibit almost constant reaction activity in these catalysts of different Ni/Cu atomic ratios implies a typical structure-insensitive reaction. The refined bio-oil produced by hydrotreating (HDY and HDO) had significantly lower iodine value, acid value, and kinetic viscosity than the raw bio-oil and the higher heating value (HHV) was increased by about 10%.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.158-159
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• 2022

Due to the climate crisis, various environmental regulations including greenhouse gas reduction are in effect. This is not limited to any specific industry sector, but is affecting the entire industry worldwide. For this reason, the IMO and governments of each country are announcing strategies and policies related to the shipbuilding and shipping industries. The current regulations can be partially resolved through additional facilities such as scrubbers while using existing fossil fuels, but ultimately, the emission of greenhouse gases such as CO2 from the exhaust gases generated by ships must be restricted through energy conversion. To this end, it is necessary to develop fuels that can replace traditional fuels such as oil and natural gas. Among them, hydrogen is attracting attention as a clean energy that does not emit pollutants when used as a fuel. However, hydrogen has a wide explosive range and a fast dispersion speed, so research on this is necessary. Therefore, in this paper, when hydrogen leakage occurs in the fuel preparation room of a hydrogen-powered ship, the trend was analyzed and the ventilation characteristics were investigated.

• Journal of the Korea Computer Industry Society
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• v.8 no.2
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• pp.107-112
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• 2007

Laser wave length can have evaporation effect by absorption because outer skin or tissue of focus is consisted of water almost though absorption of water occurs more than 90% almost in formation thickness of very thin floor. Can operate outer skin, steam by floor and correct incision of formation is available. Suture surgical operation is available to vein or lymph system and surgical operation region can dry and see as eye and radish bleeding surgical operation is available. Specially, stability of tube both end output about pulse by weight very, this research can cause various curative effect because can reduce bulk and control easily current wave style of medical laser using electric power conversion device of high frequency way. If introduce ZVS (Zero Voltage Switching) or ZVZCS (Zero Voltage and Zero Current Switching), is more profitable because can reduce switching damage. Because electric power department of proposed medical laser can do stable soft-switching in wide subordinate extent introducing ZVZCS technique by the first help and control department composes microcontroller, output current waveform user have free form make Result that experiment because design and manufacture, brought result that improve of 20% than existing equipment, and will be bought to get into superior result if supplement as systematic late.