• Journal of Energy Engineering
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• v.7 no.1
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• pp.35-43
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• 1998

Electrodes using for the anode electrode of direct methanol fuel cell with Pt/C and Pt/Ru/C catalyst were prepared and characterized by SEM, TEM, thermal analysis and electrochemical analysis. The half cell tests were carried out with 1 M $H_2SO_4$ electrolyte and 1 M $CH_3OH$ in order to evaluate the electrode performance. The employed electrochemical methods were cyclic vol-tammetry and potentiodynamic polarization experiments. It was found that 20 w% polytetrafluoroethylene (PTFE) content in catalyst showed the best performance due to the best platinum utilization on PTFE-containing catalyst layer. It was found that Pt/Ru/C binary catalyst inhibited the poisoning of anode electrode showing improved performance compared to the Pt/C catalyst by the adsorption of oxygen containing species on the electrode surface at same time. The apparent activation energy for methanol oxidation on the Pt/Ru/C and Pt/C catalyst layer was 11.60 kJ/mol and 26.85 kJ/mol, respectively.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.481-485
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• 1998

Hydrated aluminum sulfate, an inorganic polymer, was synthesized from kaolin in $H_2SO_4$ solution using microwave energy. The maximum rates of alumina extracted from calcined kaolin were 72.8% in a conventional process ($80^{\circ}C$, 1M, and 180min) and 99.9% in a microwave process ($90^{\circ}C$, 1M, and 60 min). Compared with the conventional one, the hydrated aluminum sulfate synthesized under the microwave process had layer structure consisting of plate-shaped large grains. After synthesis and then calcination at $1100^{\circ}C$, both products on conventional and microwave processes were ${\gamma}-Al_2O_3$ with agglomerated powders of spherical shape. The specific area of the products in conventional and microwave processes were 113.5 and $106.6m^2/g$, and their average grain sizes were 46.5 an $26.3{\mu}m$, respectively.

• Journal of the Korean Ceramic Society
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• v.26 no.6
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• pp.763-770
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• 1989

A very fine and pure mullite powder of the stoichiometric composition was prepared from aluminium isopropoxide and tetraethylorthosilicate by an alkoxide hydrolysis method using NH4OH as a catalytic agent. The gel powder obtained from the hydrolysis was calcined at 80$0^{\circ}C$ and 125$0^{\circ}C$. The average particle sizes of the powders calcined at 80$0^{\circ}C$ and 125$0^{\circ}C$ were 0.19${\mu}{\textrm}{m}$ and 0.25${\mu}{\textrm}{m}$, respectively. The specific surface areas of the powders calcined at 80$0^{\circ}C$ and 125$0^{\circ}C$ were 114.7$m^2$/g and 20.6$m^2$/g, respectively. The bending strength and fracture toughness of the mullite ceramics sintered at 1$650^{\circ}C$ were 263.1MPa and 2.30MPa.m1/2 respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.211-218
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• 1982

The specific heat capacity and density of soybean oil and soy protein composing of the soybean curd were measured between $30^{\circ}C\;and\;-40^{\circ}C$. The thermal conductivity of soybean oil was measured to be 0.160 and 0.140, $W/m{\cdot}K$ at unfrozen and frozen states, respectively. The effective thermal conductivity of the soybean curd depended not only on its water content but also on its fat and protein contents.

• Food Science and Preservation
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• v.9 no.4
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• pp.425-428
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• 2002

Growth and pigment formation in Genus Monascus(M. pilosus and M purpureus) related 15 kinds of culture media(Lin medium, SP medium, YM medium, YE medium, GMIN medium, SMO medium, MY medium, GY medium, Nishikawa medium, sucrose medium, stock culture, Mizutani medium, modified Lin medium, Toya medium and rice medium) were investigated. Mizutani medium and Lin medium among 15 kinds of the culture media showed good growth for M. pilosus, M purpureus, fresh mycelium weight cultivated for 10 days at 30$^{\circ}C$ was each 24.5∼26.9 or 15.9∼17.2 g/100 mL. The culture media which showed higher content of pigment production in two fungi were Lin medium(OD: 1.2 ∼ 1.6 and Mizutani medium(OD: 0.8 ∼ 1.0) that showed higher in M. pilosus.

• Journal of Microbiology and Biotechnology
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• v.9 no.1
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• pp.32-38
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• 1999

A biosurfactant produced by Tsukamurella sp. 26A was purified by procedures including acid precipitation, ethylacetate extraction, and adsorption chromatography. The purified biosurfactant reduced the surface tension of water from 72 mN/m to 30 mN/m at a concentration of 250 mg/l, whereas the minimum interfacial tension against n-hexadecane was lowered to 1.5 mN/m at a concentration of 40 mg/i. The compound stabilized oil-in-water emulsions with a variety of commercial oils and had strong emulsification and stabilization activities when compared to those of commercial emulsifiers and stabilizers. Surface tension was stable over a broad range of pH (2-12) and temperature ($100^{\circ}C$, 3h). The biosurfactant was identified as glycolipid having a hydrophilic moiety of trehalose.

• Korean Journal of Microbiology
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• v.30 no.4
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• pp.305-309
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• 1992

Cytosine deaminase (EC 3.5.4.1) from BaciNus stc~urorhermophilus was partially purified 7.2-fold with an overall yield of 52.7%. The partially purified enzyme deiiminated cytosine only.but not 5-methylcytosine and 5-fluorocytosine. The apparent Michaclis constant. Km valuefor cytosine was 5.9 mM. The enzyme was relatively stable in the range of pH 4.0 to 7.0.furthermore extremely thermo-stable : more than 75'X) of the activity was remained afterheating at 80$^{\circ}$C for I0 min at pH 6.5. The enzyme had a pH optimum at around pH7.0 to 7.5. and temperature optimum at 35 to 31$^{\circ}$C. And the activation energ (En value)determined from an Arrhenius plot was 26 Kcal/mol. The enzyme activity was stronglyinhibited by heavy metal ions such as Cd", Hg". Cut' at 1 mM, anJ by o-phenanthroline,and p-chloromcrcuribcnzoate at I mM. But the enrymc activity was activatetl increased byGMP, and CMP at 1 mM.ased by GMP, and CMP at 1 mM.

• Bulletin of the Korean Chemical Society
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• v.14 no.2
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• pp.266-271
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• 1993

The reaction of $(CO_5$)M=C(OMe)Tol (M=Cr, Mo, W and $Tol=p-C_6H_4Me)$ and $BBr_3$ followed by treatment with tetramethylethylenediamine (TMEDA) yields a mixture of two diastereomers, trans, $cis-Br(CO)_2(tmeda)M{\equiv}$CTol [M=Cr(1a), Mo(2a), W(3a)] and cis, $trans-Br(CO)_2(tmeda)M{\equiv}$CTol [M=Cr(1b), Mo(2b), W(3b)], respectively. These compounds have been isolated as crystalline solids and characterized by spectroscopic (infrared, mass, $^1H$ and $^{13}C-NMR)$ data. The trans, cis-Br(CO)2(tmeda)Cr${\equiv}$CTol (1a), has been examine via a single crystal X-ray diffraction study : $BrCrO_2N_2C_{16}H_{23}$, Mr=407.27, triclinic, $P{\bar{1}},\;a=12.792(2),\;b=13.400(5),\;c= 11.645(4)\;{\AA},\;{\alpha}=101.26(2)^{\circ},\;{\beta}=103.04(2)^{\circ},\;{\gamma}=91.88(2)^{\circ},\;{\nu}=1907(1){\AA}^3,\;Z=2,\;{\rho}(calcd)=1.418\;gcm^{-3},\;{\lambda}(MoK{\alpha})=0.71069\;{\AA},\;{\mu}=26.25 cm^{-1},\;F(000)=831.97,\;T=295K,\;R=0.0977$ for 1332 significant reflections $[F_0>5{\sigma}(F_0)]$. There are two essentially equivalent molecules in the crystallographic asymmetric unit. Each molecule is octahedral with the bromide ligand trans to the alkylidyne carbon, the two cis-carbonyl ligands, and the bidentate TMEDA ligand.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2609-2614
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• 2010

Temperature compensation circuit is implemented by using the temperature sensor, and Intermodulation (IM) Specification of Power Amplifier is satisfied in the temperature range of $-30^{\circ}C{\sim}60^{\circ}C$ with this temperature compensation circuit. The output voltage of temperature compensation circuit which vary 170mV with the temperature is applied to the gate of TR in 3W output power Amplifier. As the result, right 3rd IM component is -18.5~-26dBm, left 3rd IM component is -18.5~-35dBm, and the left and right 5th IM component is -24~-26dBm in the temperature range of $-30^{\circ}C{\sim}60^{\circ}C$. It is confirmed that IM specification of power amplifier which is under -17dBm in the whole temperature range is satisfied.

• ALGAE
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• v.26 no.1
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• pp.73-77
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• 2011

A dominant planktonic bloom-forming species, Mallomonas elongata was isolated from a small shallow eutrophic pond. The growth characteristics of this species on variable silicate concentrations and light intensities were investigated in laboratory unialgal cultures. In culture condition of $15^{\circ}C$, the maximum population growth and the highest growth rate of M. elongata occurred at a light intensity of $80\;{\mu}mol\;m^{-2}s^{-1}$, and in culture condition of $18^{\circ}C$, it exhibited the maximum population growth and the highest growth rates at a light intensity of $50\;{\mu}mol\;m^{-2}s^{-1}$. Silicate concentration had no effect on the population growth and growth rate of M. elongata.