• Bulletin of the Korean Chemical Society
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• v.31 no.5
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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.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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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.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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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.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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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.

• Korean Journal of Pharmacognosy
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• v.49 no.1
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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.

• Journal of the Korean Society of Safety
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• v.2 no.1
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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. $${\gamma}_{pn}=9.42{\times}10^{-7}\;\frac{[Zn^{2+}][(HR)_2]^{3/2}}{[H^+]^{3/2}}$$

• Journal of Korea Multimedia Society
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• v.12 no.1
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• pp.50-57
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• 2009

This paper proposes a extraction of feature lines on a polygonal model using local implicit surface fitting technique. To extract feature lines on a polygonal model, the previous technique addressed to compute the curvature and their derivatives at mesh vertices via global implicit surface fitting. It needs a user-specified precision parameter for finding an accurate projection of the mesh vertices onto an approximating implicit surface and requires high-time consumption. But we use a local implicit surface fitting technique to estimate the local differential information near a vertex by means of an approximating surface. Feature vertices are easily detected as zero-crossings, and can then be connected along the direction of principal curvature. Our method, demonstrated on several large polygonal models, produces a good fit which leads to improved visualization.

• Fisheries and Aquatic Sciences
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• v.25 no.2
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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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• v.48 no.3
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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).

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.3
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• pp.390-395
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• 2012

Response surface methodology was used to monitor the characteristics of Corni fructus. A maximum electron donating ability of 81.27% was obtained at 119.71 W of microwave power, 7.71% of ethanol concentration, and 4.21 min of extraction time. The maximum inhibitory effect on tyrosinase was 105.92% at 143.36 W of microwave power, 58.19% ethanol concentration, and 6.71 min of extraction time. The maximum superoxide dismutase like activity was 87.08% under the extraction conditions of 107.33 W of microwave power, 96.14% ethanol concentration, and 31.49 min of extraction time. The total polyphenol content showed a maximum of 475.86 mg% at 140.29 W of microwave power, 27.44% ethanol concentration, and 58.69 min of extraction time. Based on the superimposition of four-dimensional RSM data regarding the electron-donating ability, inhibitory effect on tyrosinase, superoxide dismutase like activity, and total polyphenol content, the optimum ranges of extraction conditions were found to be at 78~98 W of microwave power, 3~33% ethanol concentration, and 3.6~9 min of extraction time.