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        검색결과 102

        81.
        2013.12 KCI 등재 서비스 종료(열람 제한)
        To investigate optimal condition of acid-catalyzed hydrothermal hydrolysis of Laminaria japonica, the main constituentsof Laminaria japonica such as cellulose, alginic acid and mannitol were hydrolyzed using acid-catalyzed hydrothermalreaction. Then, we proposed the re-designed experimental method including the predicted optimal conditions of the mainconstituents and performed acid-catalyzed hydrothermal hydrolysis of Laminaria japonica. The coefficients ofdetermination (R2) of Y5 (yield of reducing sugar from Laminaria japonica) were 0.877. P values of Y5 were 0.002,indicating significance, within 1% (p<0.01). The optimum reaction condition for acid-catalyzed hydrothermal hydrolysisof Laminaria japonica determined by the response surface methodology is 143.65oC of reaction temperature, 22min ofreaction time, hydrochloric acid concentration 0.108N, resulting in a production rate of 115.62mg/g-Laminaria japonica.
        82.
        2013.11 서비스 종료(열람 제한)
        Hydrolysis of triacylglycerol(TAG) from fats and oils to glycerol and free fatty acid (FFA), also referred to as fat splitting, is an important reaction for the olechemical industry. Typically, hydrolysis is carried out at 100-260℃ and 100-7000 kPa using 0.4-0.15(w/w) initial water to oil ratio with or without catalysts. It is an endothermic reaction occurs in a stepwise manner where TAG is initially hydrolyzed to diacyglycerol (DAG) then to monoacylglycerol(MAG) and finally to glycerol. Water, in its subcritical state, can be used as both a solvent and reactant for the hydrolysis of triglycerides. subcritical water (150℃<T<370℃,0.4<p<22Mpa) can act as an acid or base catalyst. To investigate milder reaction conditions, in this study, waste cooking oil and fresh soybean oils will be hydrolyzed to free fatty acids with deionized water under SC CO2 medium in a batch reactor. Effects of the reaction temperature, time and solvent to feed ratio on FFA in the hydroysis at equilibrium will also observed for optimum conversion of oil. The reaction products will be analyzed by acid-base titration, GC FID and HPLC.
        83.
        2013.09 KCI 등재 서비스 종료(열람 제한)
        Diverse studies are being conducted on sewage sludge treatment and recycling methods, but the demand for a lowcost treatment technology is high because the sewage sludge has an 80% or higher water content and a high energy consumption cost. We want to apply the thermal hydrolysis reaction that consumes a small amount of energy. The purpose of this study is to quantify the thermal conductivity of sewage sludge according to reaction temperature for optimal design of thermal hydrolysis reactor. We quantified continuously the thermal conductivity of dewatered sludge according to the reaction temperature. As the reation temperature increased, the dewatered sludge is thermally solubilized under a high temperature and pressure by the thermal hydrolysis reaction. Therefore, the bond water in the sludge cells comes out as free water, which changes the dewatered sludge from a solid phase to slurry of a liquid phase. As a result, the thermal conductivity of the sludge was more than 2.6 times lower than that of the water at 293 K, but at 470 K and above, became 0.708 W/m·K, which is about 4% lower than that of the water.
        84.
        2013.06 KCI 등재 서비스 종료(열람 제한)
        This study aimed to investigate the optimal enzymatic hydrolysis conditions of alginic acid using Viscozyme® L, Celluclast® 1.5L, Saczyme®, Novozym®, Fungamyl® 800L, Driselase® Basidiomycetes sp., and Alginate Lyase, for production of reducing sugar. Response surface methodology (RSM) based on central composite rotatable design was used to study effects of the independent variables such as enzyme (1-9% v/w), reaction time (10-30 h), pH (3-7) and reaction temperature (30-70oC) on the production of reducing sugar from alginic acid. The coefficients of determination (R2) of Y1, Y2, Y3, Y4, Y5, Y6, and Y7 for the dependent variable regression equation were analyzed as 0.947 0.968, 0.840, 0.926, 0.923, 0.892 and 0.825. And the p-value of Y1, Y2, Y3, Y4, Y5, Y6, and Y7 within 1% (p < 0.01) was very significant. The optimal conditions were 1.0% of the quantity of the enzyme, 10.0 hours of the response time, pH 3 and 70.0oC of the reaction temperature, where the production rate was 483.1 mg/g-alginic acid, the highest of all the enzymes used.
        85.
        2013.04 KCI 등재 서비스 종료(열람 제한)
        Slaughter of cattle, pigs, and chickens is continuously increasing. Slaughter of chickens has especially increased by approximately 50% from 2003. The quantity of poultry slaughter waste is currently approximately 120,000 tons/year, and undergoes consigned treatment. Via this process, the waste must be used as a resource and an energy source. For this purpose, the waste volume can be reduced and solid fuel can be obtained from the THR (Thermal Hydrolysis Reaction) that consumes a small amount of energy. In this study, The test was conducted at a reaction temperature of 170-220oC and for 1h at the final temperature. According to the CST (Capillary Suction Time) and TTF (Time to Filter) evaluation, the dehydrating efficiency was good after the temperature reached 190oC, and did not significantly differ at the 190oC and higher reaction temperatures. The heating value of the dehydrated solid product was 7,000-7,700 kcal/kg, and its yield rate decreased from approximately 80% to 60% with the increase in the reaction temperature. The results of the BMP test also showed that the anaerobic digestion efficiency decreased at the reaction temperatures of 200oC and higher. From the overall evaluation of the dehydrating efficiency, solid fuel quality, and anaerobic digestion efficiency during the thermal hydrolysis of poultry slaughter waste, it is concluded that the optimal operating temperature is 190oC.
        86.
        2013.03 KCI 등재 서비스 종료(열람 제한)
        Acid hydrolysis of cellulose using hydrothermal reaction was conducted to maximize reducing sugar concentration and the response surface methodology (RSM) was applied to study the effects of independent variables, such as reaction temperature (116 ~ 184oC), reaction time (12 ~ 28 min) and hydrochloric acid concentration (HCl, 0.0159 ~ 0.1841 N) on reducing sugar concentration and production yield from the cellulose. With the optimum conditions of the acid-catalyzed hydrothermal hydrolysis, the reducing sugar (RS) was obtained as 369.14 mg-RS/g-cellulose in 172.77oC of the reaction temperature, 28.41 min of the reaction time and 0.067 N of the hydrochloric acid concentration. The glucose (Glu) was obtained as 281.94 mg-Glu/g-cellulose in 154.70oC of the reaction temperature, 11.59 min of the reaction time and 0.184 N of the hydrochloric acid concentration.
        87.
        2012.09 KCI 등재 서비스 종료(열람 제한)
        The purpose of this study was to investigate yield rate of carbon fibers reinforced epoxy composites in near-critical water. A CFRP (carbon fiber reinforced plastic) laminate stacked with twenty layers was used and the specimens were cut in 10 × 50 mm (thickness: 4 mm) size. The CFRP sample was placed and heated within the non-stirred bath autoclave with an electric furnace. The yield percentage is calculated by the weight percentage of eliminated resin. To check the surface of carbon fiber, scanning electron microscopy was employed. The results showed that the removal percentages of weight were between 53.9% and 97.1%. The best yield was significantly increased up to 97.1% when operating in 573 K (14 MPa) condition. This research suggests an basic data to design a commercial scale recycling system or a new low cost recycling system for CFRP waste.
        88.
        2012.07 KCI 등재 서비스 종료(열람 제한)
        Diverse studies are being conducted on sewage sludge treatment and recycling methods, but the demand for a lowcost treatment technology is high because the sewage sludge has an 80% or higher water content and a high energy consumption cost. For this purpose, the waste volume can be reduced and solid fuel can be obtained from the Thermal Hydrolysis Reaction (THR) that consumes a small amount of energy. The experiment was conducted at a reaction temperature of 170-220oC and maintain for 1 hour at the final temperature. According to the Capillary Suction Time (CST) and Time to Filter (TTF) evaluation, the dewater ability was good after the temperature reached 200oC and did not significantly differ at the 200oC and higher reaction temperatures. The heating value of the dehydrated solid product was 3,800-4,200 kcal/kg, and its yield rate decreased from approximately 80% to 60% with the increase in the reaction temperature. To evaluate the efficiency of anaerobic digestion, the water quality of the liquid product was analyzed based on the reaction temperature. At the temperatures of 200oC and higher, the concentration of ammonia, which increases the pH and hinders anaerobic digestion rapidly increased. From the overall evaluation of the dehydrating efficiency, solid fuel quality, and anaerobic digestion efficiency during the thermal hydrolysis of sewage sludge, it is concluded that the optimal operating temperature is 200oC.
        89.
        2012.07 KCI 등재 서비스 종료(열람 제한)
        Sugar, starch and lignocellulosic biomass has been mainly used as raw materials for the production of the bioethanol. However, the sharp fluctuation of grain prices, a threat of world famine, and hardly biodegradable substance like lignin contained in lignocellulosic materials make the pre-processing of the biomass complicated in several aspects. As a result, the focus of attention has now shifted to the ‘third biomass’ such as algae, which has a high value of energy recovery. In this study, a kind of macroalgae and its characteristic were surveyed and then, the physical, biological, chemical, combined, and hydrothermal pretreatments for its hydrolysis were deeply considered. Consequently, the macroalgae could be more effectively hydrolyzed at the combined process such as the hydrothermal-chemical or biological treatment, chemical-biological treatment and so on than the single process like the biological pretreatment.
        90.
        2012.02 서비스 종료(열람 제한)
        본 연구에서는 하수슬러지 가수분해를 통해 생성되는 아미노산의 혐기성 분해과정을 알아보기 위해 각각의 아미노산 별로 혐기성 분해를 평가하였다. 아미노산의 개별 평가를 위해, 두 종류 아미노산간의 공동대사 반응인 stickland reaction은 제한시켰고, 혐기성분해가 진행되는 동안 COD, T-N, NH4+-N, Biogas, CH4 등의 변화를 분석했다. 본 연구에서는 아미노산의 탈아미노화에 의해 생성되는 암모니아성질소를 통해 아미노산 분해율을 판단하였고, 이를 위해 각 아미노산의 질소농도를 1,000mg/L로 고정하여 연구를 진행하였다. 그 결과, 알라닌, 시스테인, 리신, 류신, 메티오닌, 아르기닌, 글리신, 히스티딘의 항목 중 시스테인, 류신, 메티오닌은 탈아미노화가 61.55%, 54.59%, 46.61% 밖에 이루어지지 않았다. 특히 시스테인과 메티오닌의 경우, 탈아미노화에 기인된 유기물질의 혐기성분해가 전혀 이루어지지 않았다. 이 3종류 아미노산이 폐수에 높게 함유되어 stickland reaction이 완벽하게 충족되지 않는 조건이라면, 이 아미노산들은 혐기성 소화 공정의 처리효율 저하의 원인이 될 수 있다고 판단된다.
        91.
        2011.01 KCI 등재 서비스 종료(열람 제한)
        In this study, reaction model and reactions rate accelerated by o-iodosobenzoate ion(IB⊖) on hydrolysis reaction of p-nitrophenyl valate(NPV) using ethyl tri-octyl ammonium mesylate(ETAMs) for quaternary ammonium salts, the phase transfer catalysis(PTC) reagent, were investigated. The effect of IB⊖ on hydrolysis reaction rate constant of NPV was weak without ETAMs solutions. Otherwise, in ETAMs solutions, the hydrolysis reactions exhibit higher first order kinetics with respect to the nucleophile, IB⊖, and ETAMs, suggesting that reactions are occurring in small aggregates of the three species including the substrate(NPV), whereas the reaction of NPV with OH⊖ is not catalyzed by ETAMs. Different concentrations of NPV were tested to measure the change of rate constants to investigate the effect of NPV as substrate and the results showed that the effect was weak. This means the reaction would be the first order kinetics with respect to the nucleophile. This behavior for the drastic rate-enhancement of the hydrolysis is referred as 'Aggregation complex model' for reaction of hydrophobic organic ester with o-iodosobenzoate ion(IB⊖) in hydrophobic quarternary ammonium salt(ETAMs) solutions.
        92.
        2010.04 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        식물체의 플라보노이드 성분 함량 분석에 필요한 적정 가수분해 조건을 구명하기 위하여 은행잎을 이용하여 중심합성법으로 설계한 산 가수분해 시간과 HCl 농도에 따라 myricetin, quercetin, kaempferol 함량을 HPLC로 분석하고, SAS의 반응표면분석법으로 산 가수분해 조건의 최적화를 시도하였다. HCl 0.5~2.5 M, 0.5~2.5시간 범위 내에서 10개의 구간을 잡아서 최적화한 결과 1.5~1.9 M의 HCl 농도와 1
        93.
        2009.06 KCI 등재 서비스 종료(열람 제한)
        본 연구는 열수추출법에 의하여 추출한 세리신을 이용하여 단독 또는 2종의 효소를 이용하여 가수분해하고 그 가수분해물의 항산화 및 미백효과를 살펴본 것이다. 여러 산업용효소 중 세리신에 대한 분해효과가 우수한 alcalase, flavourzyme 및 protamex를 이용하여 분해한 결과 세리신의 분자량은 20 ~ 30 kDa의 범위로 감소하였으며 사용한 효소별로 특이적 가수분해물이 나타났다. 세리신 가수분해물의 항산화능을 살펴본 결과 원래 세리신에 비하여 DPPH 소거율이 높게 나타났으며 flavourzyme과 protamex를 같이 사용한 경우 약 85 %의 소거율을 나타냈다. 티로시나아제의 활성억제 효과를 살펴본 경우에는 세리신 가수분해물이 오히려 더 낮은 억제효과를 나타내었으나 세리신 가수분해물의 분획을 실시하고 활성억제 효과를 살펴본 결과 F2와 P3의 분획이 상대적으로 우수한 억제 효과를 나타내었다.
        94.
        2008.12 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        본 연구는 두유와 전두유의 효소적 가수분해에 따른 단백질의 변화를 조사하였다. 총 유리아미노산 함량을 조사한 결과 두유(SM)과 전두유(WSM)에 비해서 저분자 두유(LSM)와 저분자 전두유(LWSM)에서 높게 나타났다. 필수아미노산 함량은 SM과 LSM에서 비슷하였으나 LWSM은 WSM보다 높게 나타났다. SDS-PAGE 전기영동 패턴 분석결과 SM과 WSM에서는 의 고분자가 존재하였으나 LSM와 LWSM에서는 17 kDa 이하의 저분자 단백질
        96.
        2008.05 KCI 등재 서비스 종료(열람 제한)
        New functional surfactant, N,N-dimethyl-N-dodecyl-N-(2-methyl benzimidazoyl) ammonium chloride(DDBAC) having benzimidazole(BI) functional group have been synthesized and the critical micellar concentration of DDBAC measured by surface tentiometry and electric conductivity method was 8.9×10-4M. Micellar effects in DDBAC functional surfactant solution on the hydrolysis of p-nitrophenylacetate(p-NPA), p-nitrophenylpropionate(p-NPP) and p-nitrophenylvalerate(p-NPV) were observed with change of various pH (Tris-buffer). The pseudo first rate constants of hydrolysis of p-NPA, p-NPP and p-NPV in optimum concentration of DDBAC solution increase to about 160, 280 and 600 times, respectively, as compared with those of aqueous solution at pH 8.00(Tris-buffer). It is considered that benzimidazole functional moiety accelerates the reaction rates of hydrolysis because they act as nucleophile or general base. In optimum concentration of DDBAC solution, the rate constants of hydrolysis of p-NPP and p-NPV increase to about 1.5 and 3.0 times, respectively, as compared with that of p-NPA. It means that the more the carbon numbers of alkyl group of substrates, the larger the binding constants between DDBAC micelle and substrates are. To know the hydrolysis mechanism of p-NPCE(p-NPA, p-NPP and p-NPV), the deuterium kinetic isotope effects were measured in D2O solutions. Consequently the pseudo first order rate constant ratios in H2O and D2O solution, kH2O/kD2O, were about 2.8~3.0 range. It means that the mechanism of hydrolysis were proceeded by nucleophile and general base attack in approximately same value.
        97.
        2007.09 KCI 등재 서비스 종료(열람 제한)
        이온교환수지를 이용하여 말단기에 이중결합 생성이나 고리열림반응 없이 저분자 히알루론산(oligo HA)을 제조하였다. 제조된 oligo HA의 화장품소재로서의 활용 가능성 및 그 효능을 평가하기 위하여 fibroblast, keratinocyte 및 SIRC cell을 이용하여 독성을 평가하였고, Caco-2 cell과 인공피부를 이용하여 피부 투과도를 평가하였다. Oligo HA는 fibroblast와 keratinocyte cell에서 각각 300 g/mL 및 1,000 g/mL까지의 농도에서 독성이 없었으며 in vitro ocular test에서도 2,000 g/mL의 높은 농도에서까지 자극에 의한 세포독성이 관찰되지 않았다. Caco-2 cell을 이용한 세포 투과실험에서는 HA는 거의 투과되지 않는 것에 비해 oligo HA은 16.0 %까지 투과되었고, 인공피부를 이용한 세포투과 실험에서도 약 90 %의 상당히 높은 투과도를 보였다. 사람 피부에서 보습효과를 확인하기 위하여 oligo HA를 함유한 제형을 피부에 도포한 후 피부 수분량과 경피수분 손실량을 측정한 결과 HA와 비슷하게 우수한 보습 효과를 확인할 수 있었다. 인체 피부 누적 첩포 실험 결과, 특별한 피부 자극이 확인되지 않았다. Oligo HA는 HA의 우수한 보습력을 유지하면서 높은 피부 투과도를 갖는 보습소재로써 화장품에 유용하게 활용될 수 있음을 확인하였다.
        98.
        2007.08 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        본 연구에서는 전두유의 가수분해 조건에 따른 품질 특성을 조사하였다. 그 결과 효소제(KMF-G) 농도가 증가함에 따라 전두유 가수분해물의 당도, 칼슘 내인성, 및 총 유리아미노산 함량은 증가하였으며, SDS-PAGE 분석 결과 단백질의 분자량 변화는 0.20%(w/w)와 0.35%(w/w) 농도에서 유사한 패턴을 나타냈다. 전두유 가수분해물은 효소제(KMF-G) 농도 0.20%(w/w), 가수분해 시간 60분에서 가장 우수하게 나타났다. 전두유
        99.
        2007.06 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        국내산 녹두의 효율적 활용방안으로 녹두분말(A)와 효소제 무첨가 가수분해분말(B) 및 최적조건에서 가수분해시킨 분말(C)의 기능적 특성을 각각 비교하였다. 그 결과 단백질, 지방, 탄수화물, 회분, 수분 등 성분의 함량은 녹두 분말의 처리 방법에 따른 큰 차이가 없었다. 색도는 (B)와 (C)는 비슷한 경향을 보였으며 환원당의 함량은 (C)가 292.63 mg%로 높은 함량을 보였으며, 총 페놀 함량은 (A)와 (C)가 각각 38.63 mg%와
        100.
        2006.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        본 연구에서는 녹두의 가수분해조건에 따른 특성을 조사하였다. 그 결과 온도에 따른 효소제 처리구(-amylase와 protease 각각 0.1%(w/w))가 무처리구(대조구)에 비하여 전반적으로 우수하였다. 녹두전분의 최적 가수분해를 위하여 효소제 -amylase 0.08% 처리가 가장 우수하였으며, 녹두단백의 가수분해를 위하여 Protease를 혼합하여 분석한 결과 -amylase 0.08% (w/w)와 protease 0.12% (w/w)를
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