• Korean Journal of Medicinal Crop Science
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• v.4 no.1
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• pp.31-37
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• 1996

This study was conducted to know the odor characteristics and compounds in neutral, acidic and basic fraction from the essential oil of Valerliana fauriei root. Among the fraction from the essential oil of V. fauriei root, the content of neutral fraction was 92%, that of the acidic fraction, 6%, and that of basic and phenolic fractions, less than 1%, respectively. The neutral fraction was characterized by sweet-balsamic, woody, musky and medicinal odor. The acidic fraction had sweat-socks, valeric-like and cheese-like odor characters. The netural fraction of essential oil was fractionated by solvents with different polarities, resulting in 44% of ethyl ether fraction, 34% of pentane-ethyl ether fraction, 11% of pentane fraction and 11% of methanol fraction. The ethyl ether fraction was characterized by woody and medicinal odor and the pentane-ethyl ether fraction, by sweet-balsamic, woody and herb-like odor. The fractions were fractionated again by different solvents, and 12 chemical components including valeranone, 26 components including bornyl acetate, and 43 components including camphene were identified in the ethyl ether fraction, the pentane - ethyl ether fraction, and pentane fraction, respectively. In the acidic fraction, n-butanoic acid and other 44 components were identified, among which the most abundant ones were 3-methyl butanoic acid(42.1%), dimethoxy-2-propanoic acid(11.5%), and 5-­ethyldihydro-2H-furanone(5.7%).

• Kyungpook Mathematical Journal
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• v.45 no.2
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• pp.273-280
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• 2005

We generalize a continued fraction of Ramanujan by introducing a free parameter. We give the closed form for the continued fraction. We also consider the finite form giving $n^{th}$ convergent using partition theory.

• School Mathematics
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• v.19 no.1
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• pp.59-75
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• 2017

This study analyzed the $6^{th}$ graders' constructions about fraction operations and schemes and figured out the relationships quantitatively between operations and schemes through the written test of 432 students. The results of this study showed that most of students could do partitioning operation well, however, there were many students who had difficulties on iterating operation. There were more students who constructed partitioning operation prior to iterating operation than the opposite. The rate of students who constructed high schemes was lower than that of students who constructed low schemes according to the hierarchy of fraction schemes. Especially, there were many students who construct partitive unit fraction scheme but not partitive fraction scheme, because they could compose unit fraction but not do iterating it. And there were the high correlations between fraction operations and schemes. Given these result, this paper suggests implications about the teaching and learning of fraction.

• The Korean Journal of Food And Nutrition
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• v.30 no.6
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• pp.1286-1291
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• 2017

In this study, Pyracantha angustifolia (Franch.) C. K. Schneid was extracted with 70% methanol at room temperature for 48 hrs and concentrated under reduced pressure to measure its total polyphenol contents; furthermore, the effect of electron donating ability was examined. Methylene chloride, ethyl acetate, and methanol were used to fractionate the extract to testify total polyphenol contents, electron donating abilities, the removal abilities of superoxide radical as well as hydrogen peroxide. The total polyphenol contents were $2007.30{\pm}109.28{\mu}g\;GAE/mL$ in 70% methanol extract, $273.39{\pm}10.19{\mu}g\;GAE/mL$ in methylene chloride fraction, $80.57{\pm}0.64{\mu}g\;GAE/mL$ in ethyl acetate fraction, and $1,160.87{\pm}44.71{\mu}g\;GAE/mL$ in methanol fraction. The total polyphenol contents showed significant differences (p<0.05) between the solvents. The electron donating ability was $79.07{\pm}7.31%$ for 70% methanol extract, $22.34{\pm}0.64%$ for methylene chloride fraction, $5.33{\pm}0.28%$ for ethyl acetate fraction, and $32.26{\pm}1.10%$ for methanol fraction. The electron donating abilities were significantly different(p<0.05) between the solvents. The removal ability of superoxide radical was $0.018{\pm}0.003$ for 70% methanol extract, $0.007{\pm}0.002$ for methylene chloride fraction, $0.0147{\pm}0.003$ for ethyl acetate fraction, and nothing for methanol fraction. The measurement of hydrogen peroxide decomposition was $0.022{\pm}0.0046$ for 70% methanol extract, $0.0027{\pm}0.0015$ for methylene chloride fraction, $0.0037{\pm}0.0012$ for ethyl acetate fraction, and $0.0009{\pm}0.0001$ for methanol fraction.

• YAKHAK HOEJI
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• v.34 no.5
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• pp.365-373
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• 1990

The effects of the protein fraction of Panax ginseng on primary cultured chicken embryonic brain cells and DRG cultured with a deficient medium were studied. The protein fraction was further fractionated into four groups according to the molecular weight; larger than 10,000 dalton(fraction A), between 5,000 and 10,000 daltons(fraction B), between 1,000 and 5,000 daltons(fraction C), between 500 and 1,000 daltons(fraction D). All four protein fractions at the concentration of $100\;{\mu}g/ml$ significantly increased the number of the brain cells which promoted the neurite outgrowth. The activity of PDHC in the brain cells was elevated significantly by the protein fraction B at the concentration of $100\;{\mu}g/ml$. It was noted that $100\;{\mu}g/ml$ protein fraction C and D significantly enhanced the synthesis of protein in the brain cells. At the concentration of $100\;{\mu}g/ml$, the protein fraction B enhanced RNA synthesis and the protein fraction A significantly enhanced DNA synthesis in the brain cells. The protein fractions B, C, and D significantly promoted the neurite outgrowth of DRG at the concentration of $100\;{\mu}g/ml$.

• School Mathematics
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• v.8 no.2
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• pp.123-138
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• 2006

The fraction concept consists of various meanings and is one of the more abstract and difficult in elementary school mathematics. This study intends to analyze the fraction concept from historical and psychological viewpoints, to examine the current elementary mathematics textbooks by these viewpoints and to seek the direction for improvement of it. Basic ideas about fraction are the partitioning - the dividing of a quantity into subparts of equal size - and about the part-whole relation. So these ideas are heavily emphasized in current textbooks. However, from the learner's point of view, situations related to different meanings of fraction concept draw qualitatively different response from students. So all the other meanings of fraction concept should be systematically represented in elementary mathematics textbooks. Especially based on historico-genetic principle, the current textbooks need the emphasis on the fraction as a measure and on constructing fraction concept by unit fraction as a unit.

• The Korean Journal of Food And Nutrition
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• v.31 no.4
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• pp.543-548
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• 2018

This study was conducted to investigated the antioxidant activities of extract for Megmoondong fruit. Liriope platyphylla L. was extracted with 70% methanol at room temperature for 48 hr and concentrated under reduced pressure to measure its total polyphenol contents and electron donating ability. The total polyphenol contents were $7,253.50{\pm}335.43{\mu}g\;GAE/mL$ in 70% methanol extract, $1,239.77{\pm}9.30{\mu}g\;GAE/mL$ in methylene chloride fraction, $919.30{\pm}50.83{\mu}g\;GAE/mL$ in methanol fraction, $105.44{\pm}2.04{\mu}g\;GAE/mL$ in ethyl acetate fraction. The total polyphenol contents showed significant differences (p<0.05) between the solvents. The electron donating ability was $69.17{\pm}12.61%$ for 70% methanol extract, $33.11{\pm}1.77%$ for methylene chloride fraction, $5.19{\pm}2.59%$ for ethyl acetate fraction, and $20.16{\pm}1.04%$ for methanol fraction. The electron donating abilities were significantly different (p<0.05) between the solvents. The removal ability of superoxide radical was $0.0174{\pm}0.0007$ for 70% methanol extract, $0.0164{\pm}0.0007$ for methylene chloride fraction, $0.0172{\pm}0.0007$ for ethyl acetate fraction, and nothing for methanol fraction. The measurement of hydrogen peroxide decomposition was $0.0985{\pm}0.1021$ for 70% methanol extract, $0.0896{\pm}0.0893$ for methylene chloride fraction, $0.0115{\pm}0.0085$ for ethyl acetate fraction, and $0.0170{\pm}0.0180$ for methanol fraction. The Liriope platyphylla L. extracts obtained from methylene chloride showed significantly relevant results in the total polyphenol contents and electron donating ability, which was higher than the original extract.

• Journal of Elementary Mathematics Education in Korea
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• v.18 no.1
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• pp.37-62
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• 2014

In this thesis, we inquire into teaching method of decimal fraction concept in elementary mathematics education based on measurement activity. For this purpose, our research tasks are as follows: First, we design a experimental learning-teaching plan of 'decimal fraction' unit in 4th grade textbook and verify its effect. Second, after teaching experiment using experimental learning-teaching plan, we analyze the student's status of understanding about decimal fraction concept. As stated above, we have performed teaching experiment which is ruled by new lesson design and analysed the effects of teaching experiment. Through this study, we obtained the following results. First, introduction of decimal fraction based on measurement activity promotes student's understanding of measuring number and decimal notation. Second, operator concept of decimal fraction is widely used in daily life. Its usage is suitable for elementary mathematics education within the decimal notation system. Third, a teaching method of times concepts using place value expansion of decimal fraction is more meaningful and has less possibility of misunderstanding than mechanical shift of decimal point. Fourth, teaching decimal fraction through the decimal expansion helps students with understanding of digit 0 contained in decimal fraction, comparing of size and place value. Fifth, students have difficulties in understanding conversion process of decimal fraction into decimal notation system using measurement activity. It can be done easily when fraction is used. However, that is breach to curriculum. It is necessary to succeed research for this.

• The Mathematical Education
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• v.58 no.1
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• pp.1-20
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• 2019

As the importance of algebraic thinking in elementary school has been emphasized, the links between fraction knowledge and algebraic thinking have been highlighted. In this study, we analyzed the solution methods and characteristics of thinking by fifth graders who have not yet learned fraction division when they solved 'reverse fraction problems' (Pearn & Stephens, 2018). In doing so, the contexts of problems were extended from the prior study to include the following cases: (a) the partial quantity with a natural number is discrete or continuous; (b) the partial quantity is a natural number or a fraction; (c) the equivalent fraction of partial quantity is a proper fraction or an improper fraction; and (d) the diagram is presented or not. The analytic framework was elaborated to look closely at students' solution methods according to the different contexts of problems. The most prevalent method students used was a multiplicative method by which students divided the partial quantity by the numerator of the given fraction and then multiplied it by the denominator. Some students were able to use a multiplicative method regardless of the given problem contexts. The results of this study showed that students were able to understand equivalence, transform using equivalence, and use generalizable methods. This study is expected to highlight the close connection between fraction and algebraic thinking, and to suggest implications for developing algebraic thinking when to deal with fraction operations.

• Korean journal of food and cookery science
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• v.11 no.4
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• pp.365-369
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• 1995

The content ratios of gingerol in 4 fractions (hexane, ether, ethylacetate and hexane-ether (1:1, v/v) fraction) extracted from ginger (Zingiber officinale Roscoe) were analyzed using high performance liquid chromatography (HPLC). The content ratios of 6-gingerol in 4 fractions were hexane fraction; 49.5％, ether fraction; 20.74％, ethylacetate fraction; 21.43％ and hexane-ether (1 : 1, v/v) fraction; 93.70％. Antioxidant activities of soybean oil added 0.2％ of each ginger fraction and 0.02％ of BHT were determined by peroxide value during storage at 45$^{\circ}C$. And relative antioxidant effectiveness (RAE) was calculated as the ratio of the induction period of a given substrate oil to that of a control oil. RAE of each fraction was hexane fraction; 2.60, ether fraction; 2.33, ethylacetate fraction; 2.07 and hexane-ether (1 : 1, v/v) fraction; 2.75, BHT; 1.74. Inhibition effect of each fraction on the rat liver microsomal lipid peroxidation showed hexane fraction; 93％, ether fraction; 92％, ethylacetate fraction; 86％ in 350 g/$m\ell$ and hexane-ether (1 : 1, v/v) fraction; 89％ in 20 g/$m\ell$.