• School Mathematics
• /
• v.12 no.3
• /
• pp.439-454
• /
• 2010

This study presents how two eighth grade students generated their own algorithms in the context of fraction measurement division situations by modifications of unit-segmenting schemes. Teaching experiment was adopted as a research methodology and part of data from a year-long teaching experiment were used for this report. The present study indicates that the two participating students' construction of reciprocal relationship between the referent whole [one] and the divisor by using their unit- segmenting schemes and its strategic use finally led the students to establish an algorithm for fraction measurement division problems, which was on par with the traditional invert-and-multi- ply algorithm for fraction division. The results of the study imply that teachers' instruction based on understanding student-generated algorithms needs to be accounted as one of the crucial characteristics of good mathematics teaching.

• Carbon letters
• /
• v.3 no.3
• /
• pp.127-132
• /
• 2002

Unidirectional polymer composites were prepared using high-strength carbon fibers as reinforcement and phenolic resin as matrix precursor with keeping fiber volume fraction at 30, 40, 50 and 60% respectively. These composites were carbonized at $1000^{\circ}C$ and graphitised at $2600^{\circ}C$ in the inert atmosphere. The carbonized and graphitised composites were characterized for mechanical properties as well as microstructure. Microscopic studies were carried out of the polished surface of carbonized and graphitised composites after etching by chromic acid, to understand the effect of fiber volume fraction on oxidation at fiber-matrix interface. It is found that the flexural strength in polymer composites increases with fiber volume fraction and so does for the carbonised composites. However, the trend was found to be reversed in graphitised composites. In all the carbonized composites anisotropic region has been observed at fiber-matrix interface which transforms into columnar type microstructure upon graphitisation. The extension of strong and weak columnar type microstructure is function of fiber volume fraction. SEM microscopy of the etched surface of the sample reveal that composites containing 40% fiber volume has minimum oxidation at the interface, revealing a strong interfacial bonding.

• Journal of Educational Research in Mathematics
• /
• v.26 no.4
• /
• pp.663-682
• /
• 2016

This study conducted an analysis of strategies that the 3rd to 6th grade elementary students used when they were solving problems of comparing the size of the fractions with like and unlike denominators, and unit fractions. Although there were slight differences in the students' use of strategies according to the problem types, students were found to use the 'part-whole strategy', 'transforming strategy', and 'between fractions strategy' frequently. But 'pieces strategy', 'unit fraction strategy', 'within fraction strategy', and 'equivalent fraction strategy' were not used frequently. In regard to the strategy use that is appropriate to the problem condition, it was found that students needed to use the 'unit fraction strategy', and the 'within fraction strategy', whereas there were many errors in their use of the 'between fractions strategy'. Based on the results, the study attempted to provide pedagogical implications in teaching and learning for comparing the size of the fractions.

• KIEAE Journal
• /
• v.16 no.6
• /
• pp.13-19
• /
• 2016

Purpose: In this study, we examined outdoor air fraction using historical data of actual Air Handling Unit (AHU) in the existing building during intermediate season and analyzed optimal outdoor air fraction by control types for economizer. Method: Control types for economizer which was used in analysis are No Economizer(NE), Differential Dry-bulb Temperature(DT), Diffrential Enthalpy(DE), Differential Dry-bulb Temperature+Differential Enthalpy(DTDE), and Differential Enthalpy+Differential Dry-bulb Temperature (DEDT). In addition, the system heating and cooling load were analyzed by calculating the outdoor air fraction through existing AHU operating method and control types for economizer. Result: Optimized outdoor air fraction through control types was the lowest in March and distribution over 50% was shown in May. In case of DE control type, outdoor air fraction was the highest of other control types and the value was average 63% in May. System heating load was shown the lowest value in NE, however, system cooling load was shown 1.7 times higher than DT control type and 5 times higher than DE control type. For system heating load, DT and DTDE is similar during intermediate season. However, system cooling load was shown 3 times higher than DE and DEDT. Accordingly, it was found as the method to save cooling energy most efficiently with DE control considering enthalpy of outdoor air and return air in intermediate season.

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

• Parasites, Hosts and Diseases
• /
• v.21 no.1
• /
• pp.41-48
• /
• 1983

The activity and distribution of aspartate aminotransferase (EC 2.6. 1. 1) and alanine aminotransferase (EC 2.6.1.2) in adult Fascicle hepatica have been studied. Fasciola hepatica was fractionated by differential centrifugation into nuclear, mitochondrial and cytosolic fractions. The activity of GOT and GPT was measured by the method of Reitman and Frankel. Isozyme patterns of those enzyme were also examined by DEAE-cellulose column chromatography. The results obtained were as follows; 1. The activity of aspartate and alanine aminotransferase was about 0.55 unit and 0.92 unit per 1g of Fascicle hepatica, respectively. 2. The activity of those enzymes was relatively low compared with those in mammalian tissues. 3. The distribution of aspartate aminotransferase in the subcellular organelles showed that 71% of the activity was in cytosolic, 24% in mitochondrial and 5% was in nuclear fraction. 4. About 22% of the total alanine aminotransferase activity was found in the mitochondrial fratstion, about 66% in the cytosolic fraction. 5. Aspartate aminotransferase from cytosolic fraction was separated into two types of isozymes, whereas alanine aminotransferase from cytosolic fraction gave only one active peak on DEAE-cellulose column chromatography.

• Journal of Educational Research in Mathematics
• /
• v.15 no.3
• /
• pp.233-249
• /
• 2005

This study discusses on the historico-genetic instruction on fraction. The textbooks of the current curriculum include the variety of contexts of fraction to be intended to connect with the conception of ratio in the grade 6. However mary elementary students have understanding limited to whole-part relation only. This study propose a method on the basis of the process of measurement by an absolute unit. The idea is related to The genesis of fraction in Egypt.

• Journal of Ginseng Research
• /
• v.14 no.1
• /
• pp.10-13
• /
• 1990

Effect of an acidic polysaccharide fraction In Korean white and red ginseng on lipolytic action of Toxohormone-L was studied. Crude acidic polysaccharide fraction was extracted from main and lateral root of Korean white and red ginseng separately and purified several times. Inhibitory effect of crude polysaccharide fraction was determined by unit (1 unit is loft inhibition rate per Is sample). Yields of purified crude polysaccharide fraction of main and lateral root of red ginseng were 2.9 and 2.2 times higher than those of white ginseng, respectively. Inhibitory effects of main root of white and red ginseng, 11.hen final reaction concentrations of sample were 50, 100, 200, 500 $\mu$g/ml, were 37.2가 and 23.7% higher than those of lateral root of white and red ginseng. Inhibitory effect of main root of red ginseng was 2.3 times higher than that of white ginseng.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.9
• /
• pp.2782-2791
• /
• 1996

The effective longitudinal shear modulus(LSM) of continuous composites is studied theoretically and numerically using 3-phase unit cell model. Circular, hexagonal and rectangular shapes of reinforced fiber are considered to predict the shear modulus as a function of elastic modulus of each phase and volume fraction of interphase and reinforced fiber. It is found that rectangular fiber shape in low fiber volume fraction($v_f$<30%) and circular fiber shape in high volume fraction($v_f$>40%) shows the higher longitudinal shear modulus. Also the obtained values of LSM for rectangular array and by numerical analysis are higher than those of hexagonal array and by theoretical analysis respectively. The reinforcing effects of interphase are more significant in cases of higher fiber volume fraction and circular fiber shape. Not only the spatial distribution and shape of reinforcing fiber but also the volume of interphase have a pronounced effects on the overall LSM. It is also found that the tangent moduous of 2-and 3-phase polymer matrix composites is insensitive to the shape and distribution of reinforcing fibers.

• Journal for History of Mathematics
• /
• v.16 no.3
• /
• pp.69-76
• /
• 2003

In this article, We explained the historical origin and significance of decimal fraction, and draw some educational implications based on that. In general, it is accepted that decimal fraction was first invented by a Belgian man, Simon Stevin(1548-1620). In short, the idea of infinite decimal fraction refers to the ratio of the whole quantity to a unit. Stevin's idea of decimal fraction is significant for the history of mathematics in that it broke through the limit of Greek mathematics which separated discrete quantity from continuous quantity, and number from magnitude, and it became the origin of modern number concept. H. Eves chose the invention of decimal fraction as one of the "Great moments of mathematics."The method of teaching decimal fraction in our school mathematics tends to emphasize the computational aspect of decimal fraction too much and ignore the conceptual aspect of it. In teaching decimal fraction, like all the other areas of mathematics, the conceptual aspect should be emphasized as much as the computational aspect.al aspect.