• Korean Journal of Food Science and Technology
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• v.45 no.6
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• pp.742-746
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• 2013

This study was conducted to investigate the effect of different steaming and drying temperature conditions on the physicochemical characteristics of pumpkin powder. All the samples were steamed for 30 or 60 s and then were dried using hot air at 40, 50, 60, and $70^{\circ}C$. The moisture content decreased with an increase in the hot-air drying temperature, while the soluble solid content and yield increased. The color values, L, a, and b of the pumpkin powder decreased with increasing hot-air drying temperature. The pumpkin powder, which was steamed for 60 s had the highest water absorption and water solubility indexes. The carotenoid content of pumpkin powder was mostly destroyed with the increase in the steaming and drying temperatures. The total sugar and reducing sugar contents increased with increasing steaming and drying temperatures. Thus, the steaming and dehydration temperature conditions influenced the physicochemical characteristics of the pumpkin powder.

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.668-673
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• 2008

The objective of this study is to optimize the leaching conditions of sequential leaching and extracting processes for selective Ni recovery from spent Ni-Mo-based catalyst. The selective Ni recovery process consists of two processes of leaching and extracting process. In this 2-step process, Ni component is dissolved from solid spent Ni-Mo-based catalyst into leaching agent in leaching process and sequentially extracted to Ni complex with an extracting agent in the extracting process. The solutions of nitric acid ($HNO_3$), ammonium carbonate ($(NH_4)_2CO_3$) and sodium carbonate ($Na_2CO_3$) were used as a leaching agent in leaching process and oxalic acid was used as an extracting agent in extracting process. $HNO_3$ solution is the most efficient leaching agent among the various leaching agent. Also, the optimized leaching conditions for the efficient and selective Ni recovery were the leaching temperature of $90^{\circ}C,\;HNO_3$ concentration of 6.25 vol% and elapsed time of 3 h. As a result, Nickel oxalate having the highest yield of 88.7% and purity of 100% was obtained after sequentially leaching and extracting processes under the optimized leaching conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.456-464
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• 2016

Increasing the strength of structural materials allows their self-weight to be reduced and this, in turn, enables the structures to satisfy esthetic requirements. The yield strength of high-performance steel is almost 480 MPa, which is approximately 50% higher than that of general structural steel. The use of high strength materials, however, makes the sections more slender, which can potentially result in significant local stability problems. The strength of slender element sections might be governed by their elastic buckling behavior, and the elastic buckling strength is very sensitive to the boundary conditions. Because the web provides the boundary conditions of the compressive thin-flange, the stiffness of the web can affect the elastic buckling strength of the flange. In this study, therefore, the effects of the flange and web slenderness ratios on the elastic flange local buckling of I-girders subjected to a pure bending moment were evaluated by finite element analysis (FEA). The analysis results show that the elastic local buckling strength and buckling modes were affected not only by the web support conditions, but also by the flange and web slenderness ratios.

• Korean Journal of Food Science and Technology
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• v.40 no.3
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• pp.283-289
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• 2008

This study used response surface methodology (RSM) in an effort to optimize the hot water extraction conditions of dandelion leaves in order to increase antioxidant activity in the extract. A central composite design was applied to investigate the effects of independent variables, which included the ratio of solvent to sample ($X_1$), extraction temperature ($X_2$), and extraction time ($X_3$), on dependent variables of the extracts, including soluble solid ($Y_1$), total polyphenols ($Y_2$), total flavonoid ($Y_3$), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability ($Y_4$), 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging ability ($Y_5$), and superoxide radical scavenging ability ($Y_6$). The estimated optimal conditions were as follows: $83.77{\pm}1.07^{\circ}C$ of the extraction temperature, $20.85{\pm}0.24 mL/g$ of solvent per sample, and $1.59{\pm}0.12$ hr of extraction time. At the optimal conditions, the predicted characteristic values were: a yield of 38.98%, a total polyphenol level of $74.28{\mu}g/mg$, a total flavonoid level of $74.00{\mu}g/mg$, a DPPH radical scavenging ability ($IC_{50}$) of 0.14 mg/mL, a ABTS radical scavenging ability ($IC_{50}$) of 3.24 mg/mL, and a superoxide radical scavenging ability ($IC_{50}$) of 2.49 mg/mL.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.429-436
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• 1984

To expand the utility of barley the experiments on the extrusion characteristics of barley flour for snack processing were carried out and the effects of the extrusion conditions on the quality of the extrudates were investigated. The optimum moisture content of barley flour for snack processing was 20%. The moisture content and the density of the extrudates decreased with increasing extrusion temperature and decreasing die size. The die swell ranged from 0.98 to 2.18 according to various extrusion conditions and decreased with increasing temperature above $150^{\circ}C$. The lightness, redness and yellowness increased at higher temperature. The water absorption index and the water solubility index showed their maximum values at $180^{\circ}C$.The gelatinization degree of the extrudates increased with increasing temperature. The fracture fore, Young's modulus and maximum fiber stress decreased, but the deformation to fracture increased, with increasing temperature and decreasing die size. The yield force in puncture test showed lower values at higher temperature. The size and the fraction of the air cells increased with increasing temperature and decreasing die size. The optimum extrusion conditions of barley for snack processing were at the temperature of $180^{\circ}C$, with the die size of 4.5mm when processed at 160 rpm.

• Korean journal of food and cookery science
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• v.28 no.3
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• pp.275-283
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• 2012

This study was conducted to monitor the quality characteristics of Lespedeza cuneata ethanolic extracts, by a response surface methodology. The independent variables were the extraction temperature ($35{\sim}95^{\circ}C}$), extraction time (2~10 hr), and ethanol concentration (10~90%). The coefficients of the determinations (R2) were 0.8562 (p<0.1), 0.9787 (p<0.01), and 0.8344 (p<0.1) in total polyphenol, total flavonoid, and electron donating ability, respectively. The electron donating ability and nitrite scavenging effect were improved with an increase of ethanol concentration, rather than the extraction temperature. ORAC (Oxygen Radical Absorbance Capacity) with extraction conditions was 1,636.47~2,696.99 ${\mu}moles$ TE/g, and was increased with the increase of extraction temperature and 40~60% of ethanol concentration. Estimated conditions for the maximized extraction including the yield, total polyphenol, electron donating ability, nitrite scavenging effect, and ORAC, were $60{\sim}68^{\circ}C$ in extraction temperature, 6~7 hr in extraction time, and 38~60% in ethanol concentration.

• Clean Technology
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• v.18 no.2
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• pp.155-161
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• 2012

The purpose of this study is to remove paraffin wax binder effectively from powder injection molded part using supercritical fluids in powder injection molding process. For a thin powder injection molded part about 1-2 mm thickness, paraffin wax binder can be removed rapidly without any defect by traditional supercritical extraction process which has fixed high temperature and pressure condition. But, for a thick powder injection molded part, there are limitations in removing paraffin wax binder by the fixed high process condition because crack occurs at the beginning step. Therefore, here we studied variable condition debinding process that starts with mild process condition at the beginning step and then increase the process conditions simultaneously at each step. To find out the initial process condition that has the highest extraction yield without any defect for each sample thickness, we investigated various supercritical debinding conditions using 1-4 mm thickness ceramic injection molded sample. By using the variable condition debinding process that starts with the initial process condition at the first step and then increasing process conditions simultaneously at each step (temperature from 333.15 to 343.15 K, pressure from 12 to 27 MPa, and $CO_2$ flow rate from 1.5 to 10 L/min), over 95% of paraffin wax binder was removed from the 4 mm thick (10 mm diameter) ceramic injection molded disk samples within 5 hours.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.236-240
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• 2002

Characteristics of ostrich egg shell and optimal ashing conditions for preparation of calcium lactate were investigated. Average weight, girth, and length of ostrich egg shell with membrane (OESM) were 255.17 g, 39.50 cm, and 15.20 cm, respectively. Ostrich egg shell without membrane (OES) contained 0.35% moisture, 40.98% Ca as a maior mineral, 2.43% protein, and 235.0 mg/100 g of amino acids. Optimal ashing times for preparation of white-colored ashing powder from OES were 12 hr at $700^{\circ}C$, 80 min at 80$0^{\circ}C$, and 15 min at 90$0^{\circ}C$, respectively. These ashing conditions resulted in ashing powder with yields of 54.5~54.6% and color values of 97.26 ~97.51 for $L^{*}$, -0.30~-0.34 for $a^{*}$, and 0.63~0.98 for $b^{*}$. Ashing powders, from three different particle size ranges of OES, did not show significant differences in yield.eld.d.

• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.4
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• pp.132-140
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• 2008

Two different sensitivity classes of black cherry (Prunus serotina) under the natural growing environmental conditions were assessed adjacent to Air Monitoring Station located at Horton research center in Giles County, Virginia, USA. Ambient ozone concentrations, leaf gas exchange, and visible foliar injury were measured on-site during the growing seasons of 2000, 2001, and 2002. Ambient ozone exposures were sufficient to induce typical foliar visible injury corresponding with the reduction in photosynthetic activities only in sensitive black cherry. There were positive correlations between increasing cumulative ozone concentration and percent reduction in maximum net photosynthetic rates ($Pn_{MAX}$) under saturating light conditions and in quantum yield for carbon reduction (${\Phi}CO_2$) of sensitive black cherry compared to tolerant black cherry. There was a negative correlation between chlorophyll content and percent leaf injury in sensitive black cherry. Furthermore, $Pn_{MAX}$ was inversely related to percent leaf injury.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.66-72
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• 2018

Corn stover is known as a good candidate for a functional food ingredient when the main lignocellulosic material, lignin, is used as bioactive materials as form of polyphenolic compounds. The purpose of this study was to determine the microwave extraction conditions under which total phenolic compounds (TPC) and flavonoid contents of corn stover were maximized. Microwave-assisted extracts using sulfuric acid ranging from 0 to 1.0 mol with extraction time between 40 and 240 sec were conducted by using response surface methodology (RSM). Microwave power showed significant effects (p<0.05) and the concentrations of TPC and flavonoids increased with increased level of microwave power and extraction time. The optimum conditions for corn stover extraction were determined as 698.6 W, 240 sec, and 0 mol sulfuric acid, and the predicted value of TPC and flavonoid is 82.4 mg GAE/g DM and 18.1 mg/g DM, respectively. Microwave extraction was evaluated as an economic process with low energy consumption, short extraction and high extraction yield of bioactive including TPC and flavonoids compared to conventional extractions.