• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.325-329
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• 2018

In this study, polyphenols were extracted from Angelica, which are known to have a high antioxidant content and the extraction process was optimized using the response surface methodology. The extraction yield and the total polyphenols were set as response values for the methodology. Quantitative factors in the extraction process were the extraction time, volume ratio of alcohol/ultrapure water, and extraction temperature. When considering both the main and interaction effects, the greatest influence factor on the extraction yield and total polyphenols was the extraction time. The optimum extraction time and temperature and alcohol/ultrapure water volume ratio for angelica were 2.8 h, $56.6^{\circ}C$ and 64.0 vol% respectively. The extraction yield and total polyphenols when using the conditions were calculated to be 24.6% and 8.76 mg GAE/g. respectively. Determination coefficients of regression equations for the extraction yield and total polyphenols were 81.4 and 75.4%, respectively. Also the overall satisfaction level was found to be 0.80 and the significance was confirmed within 5%.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.267-275
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• 2020

Anthocyanins are antioxidant compounds susceptible to environmental factors. Anthocyanin encapsulation into yeast cells is a viable solution to overcome this problem. In this study, the optimal factors for anthocyanin encapsulation were investigated, including anthocyanin concentration, plasmolysis contraction agent, and ethanol concentration, and response surface methodology was evaluated, for the first time. Anthocyanin from Hibiscus sabdariffa L. flowers was encapsulated into Saccharomyces cerevisiae using plasmolysis contraction agent (B: 3%-20% w/v), ethanol concentration (C: 3%-20% v/v), and anthocyanin concentration (A: 0.15-0.45 g/ml). The encapsulation yield and anthocyanin loss rate were determined using a spectrometer (520 nm), and color stability evaluation of the capsules was performed at 80℃ for 30 min. The results of the study showed that these factors have a significant impact on the encapsulation of anthocyanin, in which ethanol agents have the highest encapsulation yield compared to other factors in the study. Statistical analysis shows that the independent variables (A, B, C), their squares (A², B², C²), and the interaction between B and C have a significant effect on the encapsulation yield. The optimized factors were anthocyanin, 0.25 g/ml; NaCl, 9.5% (w/v); and ethanol, 11% (v/v) with an encapsulation yield of 36.56% ± 0.55% and anthocyanin loss rate of 15.15% ± 0.98%; This is consistent with the expected encapsulation yield of 35.46% and loss rate of 13.2%.

• Journal of the Korean Wood Science and Technology
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• v.43 no.5
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• pp.600-612
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• 2015

We investigated the optimization of the organosolv pretreatment of yellow poplar for bioethanol production. Response surface methodology was used to determine the optimal conditions of three independent variables (reaction temperature, reaction time, and sulfuric acid (SA) concentration). Reaction temperature is the most significant variable in the degradation of xylan and lignin in the presence of an acid catalyst, and ethanol production increased with a decrease in the lignin content. The highest ethanol concentration ($42.80g/{\ell}$) and theoretical ethanol yield (98.76%) were obtained at $152^{\circ}C$ (2.5 bar) with 1.6% SA for 16 min. However, because of excessive degradation of the raw material, the overall ethanol yield was less than under other pretreatment conditions which has approximately 50% of WIS recovery rate after pretreatment. The optimal conditions for the maximum overall ethanol yield ($146^{\circ}C$ with 1.22% SA for 15.9 min) were determined with a predicted yield of 17.11%, and the experimental values were very close (17.15%). Therefore, the quadratic model is reliable.

• Journal of Life Science
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• v.20 no.11
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• pp.1691-1696
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• 2010

Neohesperidin is a natural new nutrition sweetener, widely existing in plants of dry citrus peel, which can be derived from extraction. Since the sweetness is 1,300-1,500 times greater than that of sugar, neohesperidin are widely used in fruit juices, wines, beverages, bakeries and pharmaceutical formulations, and are particularly suitable for consumption by diabetic patients. However, the yield of extraction from citrus peel waste is very low. In this study optimal yield conditions were determinedusing response surface methodology (RSM) in order to increase the neohesperidin extraction yield. The critical factors for maximum extraction yield were selected extraction pressure ($x_1$), extraction time ($x_2$), and concentration of ethanol ($x_3$). As a result, the extraction yield was improved when the extracting pressure increased. The extraction yield also increased in a time-dependent manner. When adding ethanol as an assistance solvent to the supercritical carbon dioxide, extraction yield was increased as more ethanol concentration was added. Finally, the extraction yield of neohesperidin was improved to about 162.22% compared to ethanol extraction as a conventional method.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.69-72
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• 2013

This study investigates the characteristics of biochar by slow pyrolysis at $500^{\circ}C$ for various biomass residues. Six biomass materials were tested: Tree bark, Tree stem, bagasse, cocopeat, paddy straw and palm kernel shell. In the biochar yield, the effect of ash in the raw biomass was significant for paddy straw. Excluding the ash content, the timber bark, bagasse and paddy straw had a similar biochar yield of 26-29 wt.%. Tree stem and bagasse had well developed pores in a wide size range and large surface area over $200m^2/g$. Cocopeat and PKS has significantly higher biochar yield due to the increased content of lignin, but the development of intra-particle pores and microscopic surface area was very poor. The elemental composition, pH and other properties of the biochar samples were also compared.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.4
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• pp.67-75
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• 2011

Sulfuric acid hydrolysis is a typical approach for producing cellulose nanocrystals. The method has been widely used, but it has a disadvantage of low yield of cellulose nanocrystals compared to mechanical method. To expand the application of cellulose nanocrystals in practical, we should be able to produce them with higher yield and the controlled properties. In this study, therefore, we intended to investigate the effect of sulfuric acid hydrolysis condition on the characteristics of the prepared cellulose nanocrystals. The concentration of sulfuric acid, temperature and hydrolysis time were varied, and the yield as well as diverse properties including the morphology, size and zeta potential were examined. We could obtain cellulose nanocrystals up to 70% of yield and found that the properties were dependent on the reaction condition. It would be helpful to select an appropriate condition for producing cellulose nanocrystals.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.298-301
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• 2007

Magnesium alloy sheets have unique mechanical properties such as high in-plane anisotropy/asymmetry of yield stress and hardening response. The unusual mechanical behavior of magnesium alloys has been understood by the limited symmetry crystal structure of HCP metals or by deformation twinning. In the present study, the continuum plasticity models considering the unusual plastic behavior of magnesium alloy sheet were derived for a finite element analysis. A new hardening law based on two-surface model was developed to consider the general stress-strain response of metal sheets such as Bauschinger effect, transient behavior and the unusual asymmetry. Three deformation modes observed during the continuous tension/compression tests were mathematically formulated with simplified relations between the state of deformation and their histories. In terms of the anisotropy and asymmetry of the initial yield stress, the Drucker-Prager's pressure dependent yield surface was modified to include the anisotropy of magnesium alloys.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.379-383
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• 2008

Extraction characteristics of garlic and functional properties of corresponding extract were monitored by response surface methodology (RSM). Maximum extraction yield of 26.41% was obtained at microwave power of 146.29 W, ethanol concentration of 63.31 %, and extraction time of 5.88 min. At microwave power, ethanol concentration, and extraction time of 114.84 W, 58.83%, and 1.42 min, respectively, maximum electron-donating ability (EDA) was 72.86%. Maximum nitrite-scavenging ability was 94.62% at microwave power, ethanol concentration, and extraction time of 81.83 W, 2.65%, and 3.83 min, respectively. Superoxide dismutase (SOD) showed maximum pseudo-activity of 49.12% at microwave power of 34.23 W, ethanol concentration of 33.11 %, and extraction time of 4.40 min. Based on superimposition of 4-dimensional RSM with respect to extraction yield, electron-donating ability, nitrite-scavenging ability, and pseudo-activity of SOD, optimum ranges of extraction conditions were microwave power of 0-100 W, ethanol concentration of 40-70%, and extraction time of 2-8 min.

• Journal of Electrochemical Science and Technology
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• v.10 no.4
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• pp.387-393
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• 2019

Activated carbons (ACs) are considered important electrode materials for supercapacitors because their large specific surface areas lead to high charging capacities. In the conventional synthesis of ACs, a substantial amount of carbon is lost during carbonization of a precursor. The development of a method to synthesize ACs in high yield would lower their manufacturing cost. Here, we demonstrate the synthesis of high-specific-surface-area NaOH-AC from carbon prepared via a hydrothermal carbonization (HTC) route, with a higher yield than that achieved through conventional pyrolysis carbonization. The amorphous carbon was derived from HTC of sugar and subsequently activated at 800℃ with various NaOH etchant/C ratios under a N₂ atmosphere. The AC prepared at 4:1 NaOH/C exhibited the highest surface area (as high as 2,918 ㎡ g^-1) and the highest specific capacitance (157 F g^-1 in 1 M aqueous Na₂SO₄ electrolyte solution) among the NaOH-AC samples prepared in this work. On the basis of their high specific capacitance, the NaOH-ACs prepared from HTC sugar are suitable for use as electrode materials for supercapacitors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.1
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• pp.225-228
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• 2004

Optimization of fluidized bed granulating conditions for yield, bulk density, and tapped density of powdered milk was determined using response surface methodology. Yield of powdered milk was greatly affected by feeding rate of water, and bulk density and tapped density could be reduced by decreasing of atomization pressure. The optimum conditions for fluidized bed granulating of powdered milk were predicted with 6$0^{\circ}C$ of inlet air temperature, 16 mL/min of feeding rate, and 2.1 bar of atomization pressure. Also 94% of yield 0.350 g/㎤ of bulk density, and 0.446 g/㎤ of tapped density of powdered milk could be obtained by the optimum granulating conditions.