• Food Science and Preservation
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• 제20권3호
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• pp.365-371
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• 2013

The organic acids, fuel oil contents and antioxidant activities of Yakju with the addition of rice varieties were investigated. The rice cultivars that were used in this study were Ilmi rice, Hopyung rice, Hopum rice, Hanarum rice, Anda rice and Indica rice. The study results are as follows: the pH values of Ilmi Yakju and Hanarum Yakju were 4.14 and 4.07, respectively, and those of the other Yakjus, 3.92~3.98. The total titratable acid content of the Yakju for which Indica rice was imported from Thailand was highest among the samples. The reducing sugars content of the Yakju for which Indica rice was used was higher than that of the other samples. The ethanol content of the Hanarum Yakju was higher than that of the other Yakjus, and the lowest ethanol content was found for the Indica Yakju. The major organic acid component of the Yakju was lactic acid. The total organic acid content was highest in the Indica rice Yakju. The amounts of the following main fusel oils were highest, in the following order: 2-butyl alcohol, 2-pentanol, N-propyl alcohol, acetaldehyde, ethyl acetate, methyl alcohol and 2-methyl-1-propyl alcohol. The DPPH free radical scavenging activity of the Indica rice Yakju was much higher than that of the Ilmi rice Yakju and the Hanarum rice Yakju. Also, the SOD activity of the Indica rice Yakju was strongest among all the samples. The total polyphenol content of the Indica rice Yakju was the highest among all the samples.

• Polymer(Korea)
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• 제34권6호
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• pp.540-546
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• 2010

In this manuscript, in order to reduce methanol permeability and, at the same time, to increase proton conductivity THS-PSA containing silica compound, responsible for methanol permeability reduction, and sulfonic acid, responsible for proton conductivity enhancement, was applied onto PVA/PSSA-MA membranes. And in order to improve durability, the resulting membranes, PVA/PSSAMA/THS-PSA, were exposed to 500ppm F2 gas at varying reaction times. The surface-fluorinated membranes were characterized through the measurement of contact angles, thermo-gravimetric analysis, and X-ray photoelectron spectroscopy to observe the physico-chemical changes. For the evaluation of the electro-chemical changes in the resulting membranes, its water contents, ion exchange capacity, proton conductivity, and methanol permeability were measured and then compared with the commercial membrane, Nafion 115. Finally, the membran electrode assembly(MEA) was prepared and the cell voltage against the current density was measured. As fluorination time increased, the contents of F2 increased up to maximum 4.3% and to depth of 50 nm. At 60 min of fluorination, the proton conductivity was 0.036 S/cm, larger than Nafion 115 at 0.024 S/cm, and the methanol permeability was $9.26E-08cm^2/s$, less than Nafion 115 at $1.17E-06cm^2/s$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.463-466
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• 2006

직접 알콜 연료전지는 액체인 알콜을 직접 연료전지에 공급하여 연소시킴으로써 높은 효율을 갖는 휴대용전원으로 주목받는 장치이다. 직접 알콜 연료전지에 담지체로 사용되는 탄소 소재는 넓은 표면적과 우수한 전기전도도를 가지고 있다는 장점 있으나 금속 촉매와의 상호작용이 약하여 촉매 활성에 영향을 주지 못한다. 산화물을 담지체로 사용할 경우 이러한 금속-담지체 간의 상호작용으로 인한 촉매활성 증가 및 입자성장 억제의 효과를 기대할 수 있다. 본 연구에서는, 안티몬 도핑된 주석산화물 (Sb-doped SnO2 : ATO nanoparticle)을 직접 메탄올 연료전지용 담지체어 적용하였으며 합성 과정은 다음과 같다. SnC14 5H2O SbC13, NaOH, HCl 수용액 혼합물을 삼구 플라스크에 넣고 $100^{\circ}C$ 온도에서 환류(reflux) 시킨 후 세척 및 건조하여 Air 분위기에서 열처리하였다. 합성된 산화물 수용액에 폴리올 방법으로 합성된 백금 콜로이드를 담지하였으며, 세척과 건조를 통하여 산화물에 담지된 백금 촉매를 촉매를 합성하였다. 촉매의 구조분석을 위해 XRD, TEM을 사용하였으며, 전극촉매로서의 활성을 평가하기 위해 cyclic voltammetry을 평가하였다. 본 연구에서는 백금의 담지량에 따른 Costripping voltammetry특성과 메탄올 및 에탄올 산화 반응 특성에 대하여, 탄소를 담지체로 사용한 Pt/C 촉매와 비교 평가하였다. 알콜 산화반응 평가결과, 주석산화물에 담지한 촉매가 탄소를 담지체로 사용한 촉매보다 우수한 활성을 나타내었으며 활성증가는 메탄올에 비해 에탄올 산화 반응의 경우 크게 증가하였다. 막과 비교해 보았다. $ZrO_2$ 입자는 전도성이며 동시에 친수성을 나타내기 때문에 상용 막에 비하여 함수율 및 수소이온 전도도가 우수하게 나타났다. 복합막의 이러한 물성은 $100^{\circ}C$이상의 고온에서 전해질 막 내의 물 관리를 용이하게 한다. 단위 전지 운전 온도 $130^{\circ}C$, 상대습도 37%의 운전 조건에서도 상당히 우수한 전지 성능을 보임에 따라 고온/저가습 조건에서 상용 Nafion 112 막보다 우수한 막 특성을 나타냄을 확인하였다.소/배후방사능비는 각각 $2.18{\pm}0.03,\;2.56{\pm}0.11,\;3.08{\pm}0.18,\;3.77{\pm}0.17,\;4.70{\pm}0.45$ 그리고 $5.59{\pm}0.40$이었고, $^{67}Ga$-citrate의 경우 2시간, 24시간, 48시간에 $3.06{\pm}0.84,\;4.12{\pm}0.54\;4.55{\pm}0.74 $이었다. 결론 : Transferrin에 $^{99m}Tc$을 이용한 방사성표지가 성공적으로 이루어졌고, $^{99m}Tc$-transferrin의 표지효율은 8시간까지 95% 이상의 안정된 방사성표지효율을 보였다. $^{99m}Tc$-transferrin을 이용한 감염영상을 성공적으로 얻을 수 있었으며, $^{67}Ga$-citrate 영상과 비교하여 더 빠른 시간 안에 우수한 영상을 얻을 수 있었다. 그러므로 $^{99m}Tc$<

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제3권3호
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• pp.193-200
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• 2005

[ $^{14}C$ ] and $^{3}H$ in the evaporator bottom (EB) discharged from the Nuclear power plant (NPP) were extracted simultaneously into a gaseous $^{14}CO_{2}$ and liquefied HTO by using the chemical oxidation, which is the method to oxidize samples completely using potassium persulfate and sulfuric acid. The extracted $^{14}C$ and $^{3}H$ were counted by the liquid scintillation counter (LSC) after the quench correction. To examine the recovery of $^{14}C$ using the radioactive standards, $Na_{2}^{14}CO_{3}$, $^{14}C-alcohol$, and $^{14}C-toluene$ as $^{14}C$, and HTO as $^{3}H$ were used. Also, the most suitable method for oxidizing $^{14}C-toluene$, which is difficult to be oxidized, was investigated through FT-IR spectra according to the concentration of sulfuric acid. With the identical method, $^{14}C$ and $^{3}H$ in the EB generated in the NPP were assayed in the range of $8.35{\sim}l.38{\times}10^3$ Bq/g and $2.46{\times}10^2{\sim}1.40{\times}10^4$ Bq/g, respectively.

• Korean Chemical Engineering Research
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• 제49권1호
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• pp.105-108
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• 2011

The increased concern for the security of the oil supply and the negative impact of fossil fuels on the environment, particularly greenhouse gas emissions, has put pressure on society to find renewable fuel alternatives. Compared to the traditional biofuel, ethanol, higher alcohols offer advantage as gasoline substitutes because of their higher energy density and lower hygroscopicity. For this reason, microbial fermentation is known as potential producers for sustainable energy carriers. In this study, bacterial responses including cellular and molecular toxicity were studied in three different microorganisms, such as Escherichia coli, Clostridium acetobutylicum, and Saccharomyces cerevisiae. In this study, it was analyzed specific stress responses caused by ethanol and buthanol using four different stress responsive genes, i.e. fabA, grpE, katG and recA. The expression levels of these genes were quantified by semi-quantitative reverse transcription-PCR. It was found that four genes have shown different responsive patterns when E. coli cultures were under stressful conditions caused by ethanol and buthanol, respectively. Therefore, in this study, the stress responsive effects caused by these alcohols and the extent of each stress response can be analyzed using the expression levels and patterns of different stress responsive genes.

• Membrane Journal
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• 제18권3호
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• pp.234-240
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• 2008

This work demonstrates the preparation of proton conducting crosslinked polymer electrolyte membranes by blending polystrene-b-poly(hydroxyethyl acrylate) (PS-b-PHEA) and poly(vinyl alcohol) (PVA) at 1 : 1 wt ratio. The PHEA block of the diblock copolymer was crosslinked with PVA using sulfosuccinic acid (SA) via the esterification reaction between -OH of membrane and -COOH of SA, as confirmed by FT-IR spectroscopy. Ion exchange capacity (IEC) continuously increased from 0.14 to 0.91 meq/g with increasing concentrations of SA, due to the increasing portion of charged groups in the membrane. In contrast, the water uptake increased up to 20.0 wt% of SA concentration above which it decreased monotonically. The membrane also exhibited a maximum proton conductivity of 0.024 S/cm at 20.0 wt% of SA concentration. The maximum behavior of water uptake and proton conductivity is considered to be due to competitive effect between the increase of ionic sites and the crosslinking reaction according to the SA concentration.

• Membrane Journal
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• 제17권4호
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• pp.311-317
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• 2007

Proton conducting crosslinked membranes have been prepared by polymer blending, which consist of poly(vinyl alcohol-co-ethylene) (PVA-co-PE) and poly(styrene sulfonic acid-co-maleic acid) (PSSA-co-PMA) at 50 : 50 wt ratio. Two kinds of PSSA-co-PMA copolymer with 3 : 1 and 1 : 1 the molar ratio of PSSA to PMA wereused as a proton conducting source. The ethylene content of PVA-co-PE was also changed as 0, 27 and 44 mol%. The membranes were thermally crosslinked via the esterification reaction between -OH of PVA and -COOH of PMA, as demonstrated by FT-IR spectroscopy (PVA-co-PE)/(PSSA-co-PMA) membranes with 3 : 1 the molar ratio of PSSA to PMA showed higher ion exchange capacity (IEC), lower water uptake and higher proton conductivity than those with 1 : 1 molar ratio. As the PE concentration increased, the IEC values, water uptake and proton conductivities decreased continuously. These properties were elucidated in terms of competitive effect between the concentration of sulfonic acid, hydrophilicity and the crosslinked structure of membranes.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제38권6호
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• pp.501-511
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• 2014

Bio-oil derived from biomass through fast pyrolysis process has the potential to displace a significant amount of petroleum fuels. However, the use of bio-oil in a diesel engine is very limited because of its poor properties, e.g., its low energy density, low cetane number, and high viscosity. Therefore, bio-oil should be emulsified or blended with other fuels that have high centane numbers. Because bio-oil has poor miscibility with petroleum fuels, the most suitable candidate fuels for direct mixing are alcohol fuels. In this study, bio-oil was blended with ethanol, and two types of cetane improvers were added to a blended fuel to improve the self-ignition property. The two types of cetane improvers, PEG 400 and 2-EHN, made it possible for bio-oil blended fuels to combust in a diesel engine with a maximum bio-oil content of 15 wt%. A high-compression-ratio piston is also proposed for the combustion of bio-oil in a diesel engine.

• KSBB Journal
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• 제10권3호
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• pp.304-316
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• 1995

For fuel alcohol production, enzymatic liquefaction and saccharification of tapioca starch by ${\alpha}$-amylase and glucoamylase were studied. The thermophilic ${\alpha}$-amylase Termamyl produced from Bacillus licheniformis gave a better liquefaction than the relalively low temperature enzyme BAN from B. subtilis. Oplimal temperature and pH with Termamyl were $90∼95^{\circ}C$ and 5.8, respectively. Minimal amount of Termamyl 240uc for a satisfactory liquefaction for a two-hour reaction was about 0.0125% (v/w) with respect to the mass of tapioca used. For saccharification experiments two enzymes, Novo AMG and Do-I1 enzymes were compared. The enzymatic activity of each enzyme was a little different depending on the substrate used and the latter was found to have a significant amount of ${\alpha}$-amylase activity. With Novo AMG optimal temperature was about $58^{\circ}C$ The pH optimum was 4.3 with maltose, however, with tapioca, no difference was observed between pH 4.3 and 5.7 which is a natural, unadjusted pH of liquefied tapioca. For 85% of completion of saccharification, it was necessary to use 0.0625% (v/w) of Novo AMG 400L for tapioca and to run the reaction for more than 10 hr, Packed volume of solid particles in tapioca slurry remained at around 30% during liquefaction and saccharification. This indicates that the removal of the solid particle before fermentation is not economically feasible at all, even though the solid particles make it very difficult to operate the bioreactor in a continuous mode with cell-recycle.

• Membrane Journal
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• 제14권2호
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• pp.117-125
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• 2004

Proton exchange membrane composed of PVA/PAM/ZrP was prepared and effect of PAM and ZrP contents on properties and performance of the membrane were investigated. PAM as a crosslinking agent was mixed into PVA solution with different concentration (7∼11 wt%) and the PVA/PAM solution was cast to prepare PVA/PAM crosslinked membrane. The membrane was treated in the solution of zirconyl chloride and phophoric acid to make a PVA/PAM/ZrP composite membrane. Methanol permeability, ion conductivity, swelling and ion exchange capacity of the membranes with different ZrP concentration were $10^{-8}∼l0^{-6}$ $\textrm{cm}^2$/sec, $10^{-3}~10^{-2}$ S/cm, 0.26∼1.17 g $H_2O$/g membrane and 2.59∼5.1 meq/g membrane, respectively. Hethanol permeability and ion conductivity of the PVA/PAM/ZrP membrane were improved by 18% and 23%, respectively, compared to those of the PVA/PAM membrane.