• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1192-1198
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• 2010

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants in the aquatic environment. Many pharmaceuticals are not completely removed during wastewater treatment, leading to their presence in wastewater treatment effluents, rivers, lakes, and ground water. Here, we developed analytical methods for monitoring ten pharmaceuticals from surface water by LC/ESI-MS/MS. For sample clean-up and extraction, MCX (mixed cation exchange) and HLB (hydrophilic-lipophilic balance) solid-phase extraction (SPE) cartridges were used. The limits of detection (LOD) in distilled water and the blank surface water were in the range of 0.006 - 0.65 and 1.66 - 45.05 pg/mL, respectively. The limits of quantitation (LOQ) for the distilled water and the blank surface water were in the range of 0.02 - 2.17 and 5.52 - 150.15 pg/mL, respectively. The absolute recoveries for fortified water samples were between 62.1% and 125.4%. Intra-day precision and accuracy for the blank surface water were 2.9% - 24.1% (R.S.D.) and -16.3% - 16.3% (bias), respectively. In surface wastewater near rivers, chlortetracycline and acetylsalicylic acid were detected frequently in the range of 0.017 - 5.404 and 0.029 - 0.269 ng/mL, respectively. Surface water near rivers had higher levels than surface water of domestic treatment plants.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.624-627
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• 2003

To achieve accurate and efficient extraction of the fractal feature, a progressive extraction method is developed. After establishing the boundaries of the targeted surface by enclosing it with internal and external covers, it determines the features of the surface by calculating the characteristics of such covers.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 동계학술발표회 논문집
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• pp.355-356
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• 2008

The light extraction efficiencies of GaN-based light-emitting diodes (LEDs) grown on differently patterned sapphire substrates were investigated by using the ray tracing method. It was found that angle of the pattern surface against the sapphire surface, the number of pattern per unit area were important structural factors for high extraction efficiency.

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 동계학술발표회 논문집
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• pp.95-96
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• 2008

We theoretically investigated the influence of side surface texturing on the light extraction efficiency in nitride-based light-emitting diodes (LEDs). The light extraction efficiency was expected as 1.2 times larger in a LED with textured surfaces compared to without ones.

• 생약학회지
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• 제49권1호
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• pp.65-69
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• 2018

Torilin is a major sesquiterpene of Torilis japonica (Umbelliferae) fruits and known to be a melanogenesis inhibitor. Extraction conditions are important factor for the efficient preparation to save cost and time in economic aspects. For this reason, this study was conducted to optimize the extraction condition for maximal yield of torilin. For optimization, extraction factors such as extraction solvent, extraction temperature and sample/solvent ratio were tested and optimized for maximum yield of torilin using response surface methodology with Box-Behnken design (BBD). The optimal condition was obtained as a EtOAc concentration in MeOH of 31.8%, an extraction temperature at $30.3^{\circ}C$ and a sample/solvent ratio, 1000 mg/2 ml. The torilin yield under optimal conditions was found to be 9.9 mg/g dried samples, which were well-matched with the predicted value of 10.4 mg/g dried samples. These results will provide useful information about optimized extraction conditions for the development of torilin as cosmetic therapeutics to reduce skin hyperpigmentation.

• 한국안전학회지
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• 제2권1호
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• pp.17-29
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• 1987

The extraction mechanism of Zinc from aqueous solution with D2EHPA (Di-2-Ethylhexyl Phosphoric Acid) dissolved in Kerosene was studied by the single drop method. The effect of the concentrations of reactant species on the extraction rate, Zinc and hydrogen ion in the continuous phase and D2EHPA in the dispersed, was studied for the drop rise period by the experiment. Then a theoretical analysis on the basis of Handlos-Baron modle was carried out. It becomes clear that the extraction rate was controlled by the neutral complex forming reaction at the drop surface from both analysises. From effect of the concentrations of species on the reaction rate, the extraction rate at the drop surface is considered to be as follows. $${\gamma}_{pn}=9.42{\times}10^{-7}\;\frac{[Zn^{2+}][(HR)_2]^{3/2}}{[H^+]^{3/2}}$$

• 한국멀티미디어학회논문지
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• 제12권1호
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• pp.50-57
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• 2009

본 논문은 3차원 다각형 모델에서 특징 선을 추출하기 위한 방법에 대해 제안한다. 이산 곡면으로 이루어진 다각형 모델에서 특징 선을 추출하기 위하여 기존 방법에서는 전역적인 음함수 곡면 맞춤 기법(Implicit Surface Fitting)을 이용하여 모델의 꼭지점에서 곡률과 곡률 미분 값을 측정하였다. 이러한 방법은 다각형 모델의 꼭지점에서 음함수 곡면으로 정확하게 투영할 수 있도록 사용자의 정의 파라미타를 찾아야 하며, 특징 추출을 위한 많은 계산 시간을 요구한다. 그러나 제안 방법은 지역적 음함수 곡면 맞춤 기법을 이용하여 모델의 꼭지점에 근사된 곡면을 통해 미분 정보를 측정한다. 측정된 미분 정보를 통해 쉽게 각각의 모서리에서 제로-클로싱을 통해 특징 점을 추출하고, 곡률 방향을 따라 추출된 점들을 연결하여 특징 선을 생성한다. 여러 가지 다각형 모델에서 실험을 하였고 기존 방법보다 빠르며 높은 품질의 특징 선을 추출한다.

• Fisheries and Aquatic Sciences
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• 제25권2호
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• pp.76-89
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• 2022

The Lophius litulon liver was used as raw material for the extraction of fish oil via various extraction methods. The extraction rate by water extraction, potassium hydroxide (KOH) hydrolysis and protease hydrolysis were compared and the results revealed the protease hydrolysis extraction had a higher extraction rate with good protein-lipid separation as observed by optical microscope. Furthermore, subsequent experiments determined neutrase to be the best hydrolytic enzyme in terms of extraction rate and cost. The extraction conditions of neutrase hydrolysis were optimized by single-factor experiment and response surface analysis, and the optimal extraction rate was 58.40 ± 0.25% with the following conditions: enzyme concentration 2,000 IU/g, extraction time 1.0 h, liquid-solid ratio 1.95:1, extraction temperature 40.5℃ and pH 6.5. The fatty acids composition in fish oil from optimized extraction condition was composed of 19.75% saturated fatty acids and 80.25% unsaturated fatty acids. The content of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were 8.06% and 1.19%, respectively, with the ratio (6.77:1) surpassed to the recommendation in current researches (5:1). The results in this study suggest protease treatment is an efficient method for high-quality fish oil extraction from Lophius litulon liver with a satisfactory ratio of DHA and EPA.

• Journal of the Korean Wood Science and Technology
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• 제48권3호
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• pp.364-375
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• 2020

In this study, ultrasound-assisted extraction was performed to extract ascorbic acid from rugosa rose (Rosa rugosa Thunb.) fruit. The optimal conditions were investigated by response surface methodology, using two variable including reaction time (16-44 min) and temperature (16-44℃). The ascorbic acid extraction was sensitive to the reaction time rather than the reaction temperature, and the optimal conditions for ascorbic acid extraction were 25℃ and 30 min. Ascorbic acid and gallic acid in the rugosa rose fruit extract were completely separated by HPLC, with a resolution factor of over 1.5 between the two. The correlation coefficient of the ascorbic acid was 0.999 in a linearity test for 50-150 ㎍/mL concentration of extract. The limit of detection and limit of quantification values were 0.16 ㎍/mL and 29.89 ㎍/mL, respectively. The relative standard deviations (RSD) for repeatability and reproducibility were determined, and each RSD showed good precision at less than 5% (N=6).

• 한국식품영양과학회지
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• 제41권3호
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• pp.390-395
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• 2012

산수유의 추출조건별 추출물의 최적 추출조건을 설정하기 위해 중심합성법에 따라 마이크로웨이브에너지(30, 60, 90, 120 및 150 watt), 에탄올 농도(0, 25, 50, 75 및 100%), 추출시간별(1, 3, 5, 7 및 9분)로 추출조건에 따라 생리활성을 측정하였다. 이때 반응표면의 회귀식 $R^2$값이 전자공여작용, tyrosinase 저해효과, SOD 유사활성, 총 폴리페놀 함량에서 각각 0.8937, 0.9254, 0.9552와 0.9708로 분석되었다. 4차원 반응표면분석에 의해 superimposing 하여 최적 추출조건을 얻은 범위는 산수유의 경우 마이크로웨이브 에너지 78~98 watt, 에탄올 농도 3~33%, 추출시간 3.6~9분으로 예측되었다.