• Education of Primary School Mathematics
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• v.14 no.3
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• pp.317-328
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• 2011

We analyzed errors committed by Korean prospective elementary teachers in finding and interpreting quotient and remainder within measurement division of fractions. 65 prospective elementary teachers were participated in this study. They solved a word problem about measurement division of fractions. We analyzed solutions of all participants, and interviewed 5 participants of them. The results reveal many of these prospective teachers could not tell what fractional part of division result means. Thses results suggest that teacher preparation program should emphasize interpreting calculation results within given situations.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1371-1377
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• 1999

Antimutagenic and antioxidative activities in the different milling fraction of rice(Oryza sativa L., illpumbyeo) were investigated. Twelve milling fractions including embryo, bran(I, II, III, IV and all) and milled rice(I, II, III, IV and V) and were obtained by abrasive milling. Antimutagenic effects of milling fraction against Trp-P-2-induced mutagenicity were shown as ${\approx}0%$ for embryo fraction, $27{\sim}86%$ for bran fractions and $64{\sim}95%$ for milled rice fractions in salmonela typhimurium reversion assay. Milled rice V, inner fraction with 80.9% milling yields, showed the highest antimutagenic activity among milling fractions Antioxidative activity, measured by peroxide value(POV) of different milling fractions was higher in embryo(28%) and bran fractions ($25{\sim}34%)$ than milled rice fractions($6{\sim}22%)$. In terms of thiobarbituric acid(TBA). embryo. bran and milled rice fractions exhibited 14, $5{\sim}21\;and \;6{\sim}20%$ antioxidative activity, respectively. Antioxidative activity, measured by electron donating ability(EDA), was 45% for embryo fraction. $35{\sim}40%$ for bran fractions and $41{\sim}65%$ for milled rice fractions. Antimutagenic activity if milling fractions was correlated with POV (r=-0.471, p<0.01) and EDA (r = 0.609, p<0.001) but not correlated with TBA. Contents of total phenolic acid and SH were higher in bran and embryo fractions than in milled rice fractions, and were reversely correlated with antimutagenic activity (r=-0.523 and -0.451. respectively, p<0.05).

• KSBB Journal
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• v.24 no.5
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• pp.469-476
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• 2009

The antioxidant activities of two crude extracts ($CH_2Cl_2$ and MeOH) and their solvent fractions (n-hexane, 85% aq. MeOH, n-BuOH, and $H_2O$ fractions) from Corydalis heterocarpa were determined by evaluating authentic $ONOO^-$ and $ONOO^-$ generated from SIN-1 (3-morpholinsydnonimine) in vitro as well as by measuring the degree of occurrence of intracellular reactive oxygen species (ROS) and nitric oxide (NO). Scavenging activities of solvent fractions on authentic $ONOO^-$ increased in the order of n-BuOH > 85% aq. MeOH > $H_2O$ > n-hexane fractions, while those on $ONOO^-$ generated from SIN-1 increased in the order of n-BuOH > 85% aq. MeOH > $H_2O$ > n-hexane fractions. In addition, all solvent fractions effectively inhibited the intracellular ROS and NO levels. The n-BuOH fraction especially exhibited the strongest ROS scavenging effect. Further purification of n-BuOH fraction led to the isolation of cnidimoside A, which presented the potent ROS scavenging effect at $10\;{\mu}M$. From these results, extracts of C. heterocarpa and its component, cnidimoside A, were predicted to be potentially useful as ingredients for protecting against oxidation.

• Education of Primary School Mathematics
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• v.8 no.2 s.16
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• pp.97-113
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• 2004

The purpose of this study is to develop instructional methods for the formalized algorithm through informal knowledge in teaching division of fractions. The following results have been drawn from this study: First, before students learn formal knowledge about division of fractions, they knowledge or strategies to solve problems such as direct modeling strategies, languages to reason mathematically, and using operational expressions. Second, students could solve problems using informal knowledge which is based on partitioning. But they could not solve problems as the numbers involved in problems became complex. In the beginning, they could not reinvent invert-and-multiply rule only by concrete models. However, with the researcher's guidance, they can understand the meaning of a reciprocal number by using concrete models. Moreover, they had an ability to apply the pattern of solving problems when dividend is 1 into division problems of fractions when dividend is fraction. Third, instructional activities were developed by using the results of the teaching experiment performed in the second research step. They consist of student's worksheets and teachers' guides. In conclusion, formalizing students' informal knowledge can make students understand formal knowledge meaningfully and it has a potential that promote mathematical thinking. The teaching-learning activities developed in this study can be an example to help teachers formalize students' informal knowledge.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.1
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• pp.1-17
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• 2019

In this study, prospective teachers were involved in arranging the teaching sequence of multiplication and division of fractions and decimal numbers based on their experience and knowledge of school mathematics. As a result, these activities provided an opportunity to demonstrate the prospective teachers' perception. Prospective teachers were able to learn the knowledge they needed by identifying the differences between their perceptions and curriculum. In other words, prospective teachers were able to understand the mathematical relationships inherent in the teaching sequence of multiplication and division of fractions and decimal numbers and the importance and difficulty of identifying students' prior knowledge and the effects of productive failures as teaching methods.

• Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.237-242
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• 2013

We investigated the antioxidant and angiotensin I converting enzyme (ACE) inhibitory activities of red snow crab Chionoecetes japonicas shell (RSCS) hydrolysate by enzymatic hydrolysis and its molecular weight cut-off fractions. The RSCS hydrolysate was fractionated through two ultrafiltration membranes of 3 and 10 kDa cut-offs. Three fractions (<3 kDa, 3-10 kDa, and >10 kDa) were evaluated for total amino acid composition, antioxidant activities using 2'-azino-bis[3-ethylbenzthiazoline-6-sulfonic acid] ($ABTS^+$) radical scavenging and superoxide dismutase (SOD)-like activities and reducing power assays, and ACE inhibitory activity using Hou's method. Although all fractions showed activity, the <3 kDa fraction of RSCS hydrolysate exhibited the greatest $ABTS^+$ radical scavenging, SOD-like and ACE inhibitory activities. However, these fractions exhibited low reducing power. These results suggest that the low-molecular-weight enzymatic hydrolysate of RSCS could be used as a functional ingredient to control oxidative stress and ACE activity.

• Education of Primary School Mathematics
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• v.22 no.2
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• pp.129-147
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• 2019

Because of the various concepts and meanings of fractions and the difficulty of learning, studies to improve the teaching methods of fraction have been carried out. Particularly, because there are various methods of teaching depending on the type of fractions or the models or methods used for problem solving in fraction operations, many researches have been implemented. In this study, I analyzed the fractional operations of CCSSM-CA and its U.S. textbooks. It was CCSSM-CA revised and presented in California and the textbooks of Houghton Mifflin Harcourt Publishing Co., which reflect the content and direction of CCSSM-CA. As a result of the analysis, although the grades presented in CCSSM-CA and Korean textbooks were consistent in the addition and subtraction of fractions, there are the features of expressing fractions by the sum of fractions with the same denominator or unit fraction and the evaluation of the appropriateness of the answer. In the multiplication and division of fractions, there is a difference in the presentation according to the grades. There are the features of the comparison the results of products based on the number of factor, presenting the division including the unit fractions at first, and suggesting the solving of division problems using various ways.

• Archives of Pharmacal Research
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• v.17 no.5
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• pp.371-374
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• 1994

Effects of the polysaccharide fractions purified from Artemisia selengensis and Artemisia iwayomogi on the immune system was studied. The polysaccharide fractions, respectively called ASP1 and AIP1, may interact with macrophages and lymphocytes in spleen, increasing the population of those cell types in vivo and in vitro. Both ASP1 and AIP1 fractions also syuppress transplanted tumor cell growth and augment antibody production. This study suggests that ASP1 and AIP1 fractios may have immunomodulating and antitumor activities.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.2
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• pp.196-203
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• 2023

We investigated the nutritional characteristics and antioxidant effects of sea mustard Undaria pinnatifida fractions from Gultongmeori in Taejongdae, Youngdo, Busan. Based on dry weight, the moisture, crude protein, crude lipid, crude ash, and crude fiber contents were 34.98%, 11.55%, 0.43%, 17.82%, and 3.45%, respectively. To evaluate the antioxidant effect, we used radical scavenging (DPPH and ABTS), reactive oxygen species (ROS) production measurement, and DNA oxidation assays. Total flavonoid and phenol contents were higher in the n-hexane fraction than in other fractions. The n-hexane fraction was more effective at scavenging free radicals than other fractions as assessed using DPPH and ABTS assays (P<0.05). The ROS production assay showed that all sea mustard fractions decreased H₂O₂ induced cellular ROS production compared to that seen in the control (P<0.05); however, the n-hexane fraction reduced cellular ROS production to a greater extent than the other fractions. Furthermore, the n-hexane fraction from Gultongmeori significantly inhibited genomic DNA oxidation. These results indicate that the antioxidant effect of sea mustard is associated with its high flavonoid and phenol content. This study proposes that processed food products supplemented with sea mustard can be developed as functional foods to promote health in the local population.

• Journal of Elementary Mathematics Education in Korea
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• v.19 no.4
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• pp.563-588
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• 2015

In elementary school, didactical transposition is inevitable due to several reasons. In mathematics, addition and multiplication are taught as binary operations, subtraction and division are taught as unary operations. But in elementary school, we try to teach all the four operations as binary operations by didactical transposition. In 'Mastering' the concepts of the four operations, the way of concept introduction is dealt importantantly. So it is different from understanding the four operations. In this study, we analyzed the four operations of natural numbers and fractions from two perspectives: concept understanding (how to introduce concepts and how to choose an operation) and connection between the operations. As a result, following implications were obtained. In division of fractions, students attempted a connection with multiplication of fractions right away without choosing an operation, based on the situation. Also, to understand division of fractions itself, integrate division of fractions presented from the second semester of the fifth grade to the first semester of the sixth grade are needed. In addition, this result can be useful in the future textbook development.