• 한국수학교육학회지시리즈A:수학교육
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• 제48권3호
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• pp.235-263
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• 2009

The purpose of the study was to investigate the influence of children's understanding of fractions in mathematics problem solving. Kieren has claimed that the concept of fractions is not a single construct, but consists of several interrelated subconstructs(i.e., part-whole, ratio, operator, quotient and measure). Later on, in the early 1980s, Behr et al. built on Kieren's conceptualization and suggested a theoretical model linking the five subconstructs of fractions to the operations of fractions, fraction equivalence and problem solving. In the present study we utilized this theoretical model as a reference to investigate children's understanding of fractions. The case study has been conducted with 6 children consisted of 4th to 5th graders to detect how they understand factions, and how their understanding influence problem solving of subconstructs, operations of fractions and equivalence. Children's understanding of fractions was categorized into "part-whole", "ratio", "operator", "quotient", "measure" and "result of operations". Most children solved the problems based on their conceptual structure of fractions. However, we could not find the particular relationships between children's understanding of fractions and fraction operations or fraction equivalence, while children's understanding of fractions significantly influences their solutions to the problems of five subconstructs of fractions. We suggested that the focus of teaching should be on the concept of fractions and the meaning of each operations of fractions rather than computational algorithm of fractions.

• 대한수학교육학회지:수학교육학연구
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• 제11권1호
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• pp.223-238
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• 2001

Decimal fractions are the practical system of notations representing real numbers. The set of decimal fractions with the definition of comparison of decimal fractions and the identification of their double representations is essentially the field of real numbers. Therefore, we have to clarify the concept of decimal fractions. However, there are problematics that the aquisition of the concept of decimal fractions is not easy. In this paper, we attempt to eradicate the problematics relevant to the acquisition of decimal fractions discussed above and find the desirable direction of instruction of meaning for mathematical symbols: The case of decimal fractions. In J. Hiebert & decimal fractions. First of all, we clarify the essence of them - ratio, operator and linearity. And we compare and analyse the theories about decimal fractions of Resnick, Drexel, Brousseau and Hiebert and the contents of texts about decimal fractions in Korea. Finally, we suggest the efficient instruction methods which are faithful to the essence of decimal fractions and choose some methods among them to plan the classroom instruction and implement the methods in the classroom.

• 한국잠사곤충학회지
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• 제40권2호
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• pp.131-135
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• 1998

Changes of silk fibroin molecular weight was studied by enzymatic proteolysis and reverse reaction of enzymatic proteolysis (plastein reaction) using chromatography, X-ray diffraction and thermal analysis methods. When the treatment of enzymatic proteolysis with $\alpha$-chymotripsin to silk fibroin solution, a precipitate of Fcp fractions was formed. And, this was dissolved in LiBr aqueous solution, the precipitate of PIFcp fractions was obtained again. Fcp and PIFcp fractions showed silk IIand silk Itype structure, respectively. Fcp fractions was about 6,900 in molecular weight, PIFcp fractions obtained by plastein reaction on the precipitate of Fcp fractions increased molecular weight to abort 15,000. The molecular weight of Fcp fractions was increased by plastein reaction, but Fcp fractions almost transited to silk I type crystal. The structure of silk I type of PIFcp fractions was steady identified by X-ray diffraction and thermal analysis. As molecular weight of Fcp fractions was gradually low, PIFcp fractions was become to macromolecule little by little.

• 한국수학교육학회지시리즈A:수학교육
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• 제51권1호
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• pp.21-45
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• 2012

The purpose of the study was to investigate how students understand each operations with whole numbers and fractions, and the relationship between their knowledge of operations with whole numbers and conceptual understanding of operations on fractions. Researchers categorized students' understanding of operations with whole numbers and fractions based on their semantic structure of these operations, and analyzed the relationship between students' understanding of operations with whole numbers and fractions. As the results, some students who understood multiplications with whole numbers as only situations of "equal groups" did not properly conceptualize multiplications of fractions as they interpreted wrongly multiplying two fractions as adding two fractions. On the other hand, some students who understood multiplications with whole numbers as situations of "multiplicative comparison" appropriately conceptualize multiplications of fractions. They naturally constructed knowledge of fractions as they build on their prior knowledge of whole numbers compared to other students. In the case of division, we found that some students who understood divisions with whole numbers as only situations of "sharing" had difficulty in constructing division knowledge of fractions from previous division knowledge of whole numbers.

• 한국미생물·생명공학회지
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• 제28권4호
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• pp.209-213
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• 2000

The cultured mycelia of Ganoderma lucidum were extracted and the extract was separated into six fractions by organic solvent fractionation. The antihepatotoxic activity of all the fractions was evaluated by measuring activities of glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT). Among the fractions tested, the high-polarity fractions such as aqueous and n-butanol fractions significantly reduced activities of GPT and GOT in CCl4- and galactosamine-intoxicated rat primary hepatocytes. When intracellular synthetic activities were measured by pulsing the rate primary cultured hepatocytes with [3H]-uridine and [3H]-leucine, activities of DNA, RNA and protein. When direct toxicities of the fractions were measured against human hepatoma(SK-Hep-1), the non-polarity fractions such as n-butanol and ethyl acetate fractions showed potent direct cytotoxicities even at the concentration of 1 $\mu\textrm{g}$/ml. These data showed that Ganoderma lucidum has hepatoprotective and hepatotoxic recovery principles in its mycelia.

• 대한수학교육학회지:수학교육학연구
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• 제24권1호
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• pp.83-102
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• 2014

본 연구에서는 분수 학습을 마친 초등학교 6학년 학생 150명을 대상으로 분수의 5가지 의미에 관한 20개의 문항을 제시하였고, 학생들의 반응을 단위의 이해에 초점을 두어 분석하였다. 연구 결과, 전체-부분으로서의 분수에 익숙한 학생들은 분수의 다른 의미에서도 주어진 전체를 단위로 인식하는 오류를 많이 보였다. 또한, 각 의미별로 단위와 관련된 다양한 반응들이 나타났다. 이러한 연구 결과를 바탕으로 각각의 분수의 의미를 지도할 때 단위와 관련된 강조사항을 확인하여 시사점을 제공하고자 한다.

• 한국수학교육학회지시리즈A:수학교육
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• 제57권4호
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• pp.453-475
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• 2018

This study examines how elementary students understand fractions with operations conceptually and how they perform procedures in the division of fractions. We attempted to look into students' understanding about fractions with divisions in regard to mathematical proficiency suggested by National Research Council (2001). Mathematical proficiency is identified as an intertwined and interconnected composition of 5 strands- conceptual understanding, procedural fluency, strategic competence, adaptive reasoning, and productive disposition. We developed an instrument to identify students' understanding of fractions with multiplication and division and conducted the survey in which 149 6th-graders participated. The findings from the data analysis suggested that overall, the 6th-graders seemed not to understand fractions conceptually; in particular, their understanding is limited to a particular model of part-whole fraction. The students showed a tendency to use memorized procedure-invert and multiply in a given problem without connecting the procedure to the concept of the division of fractions. The findings also proposed that on a given problem-solving task that suggested a pathway in order for the students to apply or follow the procedures in a new situation, they performed the computation very fluently when dividing two fractions by multiplying by a reciprocal. In doing so, however, they appeared to unable to connect the procedures with the concepts of fractions with division.

• 한국조리학회지
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• 제24권2호
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• pp.103-111
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• 2018

The objectives of the present study were to examine the antioxidant activity of autofocusing fractions from egg white protein hydrolysates and obtain higher antioxidant peptide fraction, which could be applied to the food model system. Alkaline protease hydrolysate of egg white protein exerted higher antioxidant activities than other protein hydrolysates and were fractionated on the basis of the amphoteric nature of sample peptides by preparative isoelectric focusing without toxic solvents and reagents, which is termed autofocusing. Neutral and basic fractions showed higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity than the acidic fractions. The acidic and neutral fractions showed higher hydroxyl (OH) radical scavenging activity and oxygen radical absorbance capacity (ORAC) values than the basic fractions. The acidic fractions showed higher metal chelating activity than basic fractions. Antioxidant activities of some autofocusing fractions except for ORAC showed higher compared to the crude hydrolysate. These results suggest that peptides fractions from egg white protein are effective antioxidant, and that autofocusing could be useful to increase antioxidant activity for application to food system.

• Journal of Ginseng Research
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• 제9권2호
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• pp.204-212
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• 1985

Lipid and fatty acid compositions of the bound lipids in Panax quinquefolium (Korea, Japan and China), Panax quinquefolium (America, Canada) and Panax notoginseng (China) were studied by means of silicic acid column chromatography, thin-layer chromatography and gas-liquid chromatography. The could lipid contents in various ginsengs were 0.29 to 0.48%, in which neutral lipid fractions were 63.6 to 67.3%, glycolipid fractions 21.9 to 25.7% and phospholipid fractions 7.7 to 12.4%. The content compositions of neutral lipid fractions were lower and those of glycolipid and phospholipid fractions were higher in the bound lipids than in the free lipids from the various ginseng. The major components were fatty acids, diglycerides and free sterols in neutral lipid fractions, monogalactosyl diglyceride, sterol glucoside and esterified steryl g1ycoside in glycolipid fractions and phosphatidyl glycerol, phosphatidyl ethanolamine and phosphatidic acid in phosphoipid fractions. Seventeen fatty acids were analyzed in the four bound lipid fractions from the various ginsengs and main fatty acids were linoleic acid, palmitic acid and oleic acid. Total saturated fatty acid and palmitic acid contents were higher and total unsaturated fatty acid and linoleic acid contents lower in the total bound lipids than in the total free lipids from the various ginsengs.

• 한국미생물·생명공학회지
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• 제24권4호
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• pp.459-464
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• 1996

Exo-polysaccharide (BWS) obtained from submerged cultivation of Ganoderma lucidum mycelium was fractionated. Antitumor activity of their fractions was investigated in comparison with the mycelial polysaccharide fractions. Eight kinds (BWS-DN, BWS-DA, BWS-DN-GI, BWS- DA-GI, MWS-DN, MWS-DA, MWS-DN-GI and MWS-DA-GI) of polysaccharide fractions were obtained by DEAE-cellulose ion exchange chromatography and Sepharose CL-4B gel chromatography from BWS and MWS, which were isolated from culture fiuid and mycelial cell, respectively. The anticomplementary activities (ITCH$_{50}$%) of the exo-polysaccharide fractions showing 15% to 30% were lower than those of mycelial polysaccharide fractions showing 15% to 70%. The acidic fractions of BWS-DA and BWS-DA-GI fractionated from BWS, showed the highest activity of 30%. In the MTT assay, BWS-DN and MWS against mouse leukemia L1210 exhibited high inhibition ratio of 86 and 89%, respectively at the concentration of 600 $\mu$g/ml. High inhibition ratio of 50% (IC$_{50}$) was achieved for BWS, BWS-DA and MWS-DA fractions against human colon adenocarcinoma COLO-205 and for BWS-DA, BWS-DN and MWS-DN fractions against human leukemia HL-60 at the concentra- tion of 300 $\mu$g/ml among the six polysaccharide fractions, respectively.