• 공업화학
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• 제29권3호
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• pp.325-329
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• 2018

본 연구에서는 항산화성분함량이 높다고 알려진 안젤리카를 이용하여 폴리페놀을 추출하고 반응표면분석법을 이용하여 추출과정을 최적화하였다. 반응표면분석법의 반응치로는 추출수율과 폴리페놀함량을 설정하였고, 추출공정의 계량인자로는 추출시간, 주정/초순수 부피비, 추출온도를 이용하였다. 추출수율과 폴리페놀함량 모두 계량인자의 주효과도와 교호효과도를 모두 고려하였을 때 가장 큰 영향을 미치는 인자는 추출시간이었다. 또한 반응표면분석 결과 안젤리카의 최적추출조건은 추출시간이 2.8 h, 주정/초순수 부피비 64.0 vol%, 추출온도 $56.6^{\circ}C$로 나타났다. 이 조건의 추출수율은 24.6%, 폴리페놀함량은 8.76 mg GAE/g으로 산출되었다. 추출수율과 폴리페놀함량에 대한 회귀방정식의 결정계수 $R^2$은 각각 81.4%와 75.4%이었으며, 종합 만족도는 D = 0.80, 유의성은 5% 이내의 수준에서 인정되었다.

• 한국미생물·생명공학회지
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• 제48권3호
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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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• 제43권5호
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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.

• 생명과학회지
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• 제20권11호
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• pp.1691-1696
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• 2010

감귤류는 다양한 기능성과 약효로써의 효능이 입증되면서 소비가 증가하고 있으나, 감귤 가공 후 부산물인 감귤박은 폐기물로써 해양에 투기되고 있어 부산물의 처리가 시급한 실정이다. 따라서 폐감귤박을 이용한 고감도 감미료의 생산 원료인 neohesperidin을 추출하여 폐감귤박을 효율적 이용을 도모하였으나 상당히 미비한 추출수율로 효율성이 감소하였다. 이러한 추출 수율의 문제점을 해결하기 위하여 반응표면 분석법을 이용하여 감귤가공부산물로부터 neohesperidin의 추출 수율 증진 위한 추출조건의 최적화 연구를 수행하였다. 추출 조건 중 초임계 유체 추출의 수율 증진에 영향을 주는 추출 압력($x_1$), 추출 시간($x_2$), 보조용매의 농도($x_3$)를 주요 인자로 선정하였다. 선정한 인자를 반응표면 분석법에 적용하여 추출 수율의 최적조건을 탐색하였으며, 그 결과 추출압력이 증가하면서 추출의 수율은 크게 향상되었고, 또한 추출 시간이 길어질수록 추출 수율 또한 증가함을 확인하였다. 또한 초임계 이산화탄소에 ethanol을 보조용매로 첨가할 경우 보조용매의 농도가 높을수록 수율은 급격하게 증가하여, 최종적으로 162.22%까지 neohesperidin의 추출 수율을 증진할 수 있었다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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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.

• 펄프종이기술
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• 제43권4호
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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.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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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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• 제17권2호
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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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• 제10권4호
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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.

• 한국식품영양과학회지
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• 제33권1호
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• pp.225-228
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• 2004

반응표면분석법(RSM)을 활용하여 유동층과립기의 흡입공기온도, 물의 투입비율, 분무압력 등이 분유의 과립화에 미치는 영향을 분석하였다. 분유의 과립화 수율은 물의 투입 비율에 많은 영향을 받고 있음을 알 수 있었으며, 겉보기밀도 및 다짐 밀도는 분무압력에 크게 영향을 받고 있음을 보여주었다. 분유의 유동층 과립화의 최적조건은 흡입공기온도6$0^{\circ}C$, 물의 투입비율 16 mL/min, 그리고 분무압력 2.1 bar이었으며, 이때 과립화 수율은 94.0%, 겉보기밀도는 0.350 g/㎤, 그리고 다짐밀도는 0.446 g/㎤로 각각 예측되었다.