• School Mathematics
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• v.19 no.2
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• pp.229-248
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• 2017

This study investigated the factors that should be considered when teaching proportional expression and proportional distribution through literature review. Based on these results, we analyzed and compared Korean and foreign mathematics textbooks on proportional expression and proportional distribution longitudinally and horizontally to search for desirable methods of organizing the unit of proportional expression and proportional distribution in mathematics textbooks. For longitudinal analysis, we took the mathematics textbooks according to the national curriculum since the 5th one. For horizontal analysis, we selected the mathematics textbooks of Japan, Singapore, and China. In each textbook, the contents and the order in relation to proportional expression and proportional distribution, the definitions of terminology, and the contexts and the visual representations for introducing related concepts are selected as the analysis framework. The results of analysis revealed many characteristics and the differences in ways of dealing contents about proportional expression and proportional distribution. Based on these results, we suggested some implications for writing the unit of proportional expression and proportional distribution in elementary mathematics textbooks.

• The Mathematical Education
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• v.46 no.2 s.117
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• pp.141-153
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• 2007

The purpose of the study is to analyze children's proportional reasoning and problem solving in proportional problems with/without iconic representations. Proportional problems include 3 tasks such as (a) without any picture, (b) with simple picture, and (c) with/without iconic representation. As a result, children didn't show any significant differences in two tasks such as (a) and (b). However, children showed better proportional reasoning with iconic representation. In addition, 'build-up expression' strategy was used mostly in solving problems and 'additive strategy' was shown as an error which students didn't make an appropriate proportional relation expression and they made a wrong additive strategy.

• School Mathematics
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• v.9 no.4
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• pp.447-466
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• 2007

Math education in schools have to enable students to understand the importance of math and nurture the capacity to resolve various problems in daily life with reasoning, which is therefore, always applicable to the actual world. Proportional reasoning capacity is being often used in daily life, and some kind of unit is not fixed. So students are considering it very difficult. This study looks into the difficulties that students have in proportional reasoning, what kind of problem solving strategy is being used, what the problems are in current textbooks, etc. Based on this, it tried to check the concept changes in students' proportional reasoning by developing the instruction program for 'proportional expression' unit in the 6th grade. Based on the results, this study analyzes the features of proportional reasoning instruction programs and the instruction results. Also it analyzes in-advance & after examination papers of the experimental class and comparison class to contribute to the instruction method and instruction contents improvement of 'proportional expression' unit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.5
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• pp.33-38
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• 2013

This paper presents a simpler calculation of the generator load sharing according to the change of system frequency and the droop setting of turbine-generator governor. The author firstly draws a graph based on the generator operation at rated MW output and normal frequency, and secondly, builds a proportional expression using the graph in order to obtain the solution in a simpler way rather than using conventional mathematical calculation, to provide the readers with an easier understanding of the droop setting of turbine-generator governor.

• KSBB Journal
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• v.13 no.6
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• pp.662-668
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• 1998

Viruses belonging to the Hantavirus genus cause two acute severe illness in humans, i.e., Haemorrhagic Fever with Renal Syndrome (HFRS) and Hantavirus Pulmonary Syndrome(HPS). Among them, Hantaan virus is one of the most important viruses causing HFRS. Recombinant expression vectors, pKK-NP and pET-NP, with Hantaan viral nucleocapsid gene were constructed, and used to transform Eschericia coli BL21(DE3). Stability of the vectors in the host strain, and effects of some environmental conditions on the expression of nucleocapsid gene were studied. Expression vector, pKK-NP, was very unstable, and the expression level of nucleocapsid gene was very low compared to that of pET-NP. BL21(pET-NP) produced about 100 mg of N protein per liter of culture broth. Induction time did not show any significant difference on the expression level of nucleocapsid gen and cell growth. BL21(pET-NP) culture at 35$^{\circ}C$ showed a little higher expression level than at 30$^{\circ}C$ during growth phase, but reached to the same level at stationary phase. Total expression level was proportional to supplemented glucose concentration of media up to 0.5% along with cell growth, but expression level per unit cell mass was inversely proportional to glucose concentration and maximal when glucose was not supplemented at all.

• Journal of Magnetics
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• v.1 no.2
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• pp.55-56
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• 1996

The effective magnetic moment of Cr$_2$O$_3$is determined by assuming that a proportional relation holds between its moment and the effective magnetic moment of hematite determined by the previous derived relaxation expression and the moments of Fe3+ ion and Cr3+ ion. The result obtained from the relation is found to be given by 0.10 in Bohr magneton which is in good agreement with the value obtained by use of the expression.

• Education of Primary School Mathematics
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• v.25 no.1
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• pp.57-79
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• 2022

Current mathematics It is necessary to ensure that ratio and proportion concept is not distorted or broken while being treated as if they were easy to teach and learn in school. Therefore, the purpose of this study is to analyze the activities presented in the textbook. Based on prior work, this study reinterpreted the proportional reasoning task from the proportional perspective of Beckmann and Izsak(2015) to the multiplicative structure of Vergnaud(1996) in four ways. This compared how they interpreted the multiplicative structure and relationships between two measurement spaces of ratio and rate units and proportional expression and proportional distribution units presented in the revised textbooks of 2007, 2009, and 2015 curriculum. First, the study found that the proportional reasoning task presented in the ratio and rate section varied by increasing both the ratio structure type and the proportional reasoning activity during the 2009 curriculum, but simplified the content by decreasing both the percentage structure type and the proportional reasoning activity. In addition, during the 2015 curriculum, the content was simplified by decreasing both the type of multiplicative structure of ratio and rate and the type of proportional reasoning, but both the type of multiplicative structure of percentage and the content varied. Second, the study found that, the proportional reasoning task presented in the proportional expression and proportional distribute sections was similar to the previous one, as both the type of multiplicative structure and the type of proportional reasoning strategy increased during the 2009 curriculum. In addition, during the 2015 curriculum, both the type of multiplicative structure and the activity of proportional reasoning increased, but the proportional distribution were similar to the previous one as there was no significant change in the type of multiplicative structure and proportional reasoning. Therefore, teachers need to make efforts to analyze the multiplicative structure and proportional reasoning strategies of the activities presented in the textbook and reconstruct them according to the concepts to teach them so that students can experience proportional reasoning in various situations.

• The Journal of Korean Obstetrics and Gynecology
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• v.19 no.3
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• pp.135-149
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• 2006

Purpose : This study was aimed to investigate the inhibitory effect of Millettia Reticulatas on the proliferation of human uterine leiomyoma cells and the expression of gene related the mechanism of cell apoptosis. Methods : We counted the number of death cells treated with indicated concentration of Millettia Reticulatas and investigated cell death rate by MTS assay. Furthermore, flow cytometry analyis and DNA fragmentation assay were used to dissect between necrosis and apoptosis. and then we observed the differential gene expression by western blot analysis. Results : 1) The inhibitory effect on the growth of uterine leiomyoma cell treated with Millettia Reticulatas was increased in a concentration proportional. 2) The result of flow cytometry analysis. subG1 phase arrest related3 cell apoptosis was investigated 23.49% in uterine leiomyoma cell treated Millettia Reticulatas and showed the fession of proportional concentration. 3) The gene expression of p27, p53, p21, p16 related cell cycle was increased according to increasing concentration but cyclin E was none exchanged. 4) The character of apoptosis, DNA fragmentation was significantly observed the fession of proportional concentration. 5) The expression of pro-caspase3 and PARP were decreased dependent on treatment concentration. Conclusion : This study showed that Millettia Reticulatas have the inhibitory effect on the proliferation of human uterine leiomyoma cell and the effect was related with apoptosis. The apoptotic mechanism was observed that the gene expression of p27, p53, p21, p16 related cell cycle was increased according to increasing treatment concentration, induced G1 phase arrest and finally cell death was occurred. The decreased expression of pro-caspase 3 and PARP were noted that apoptosis was related with caspase pathway.

• Journal of Elementary Mathematics Education in Korea
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• v.13 no.2
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• pp.211-229
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• 2009

The purpose of this study is analysis of to investigate relation proportion problem of mathematics textbooks of 7th curriculum to proportional reasoning(relative thinking, unitizing, partitioning, ratio sense, quantitative and change, rational number) of Lamon's proposal at sixth grade students. For this study, I develop two test papers; one is for proportion problem of mathematics textbooks test paper and the other is for proportional reasoning test paper which is devided in 6 by Lamon. I test it with 2 group of sixth graders who lived in different region. After that I analysis their correlation. The result of this study is following. At proportion problem of mathematics textbooks test, the mean score is 68.7 point and the score of this test is lower than that of another regular tests. The percentage of correct answers is high if the problem can be solved by proportional expression and the expression is in constant proportion. But the percentage of correct answers is low, if it is hard to student to know that the problem can be expressed with proportional expression and the expression is not in constant proportion. At proportion reasoning test, the highest percentage of correct answers is 73.7% at ratio sense province and the lowest percentage of that is 16.2% at quantitative and change province between 6 province. The Pearson correlation analysis shows that proportion problem of mathematics textbooks test and proportion reasoning test has correlation in 5% significance level between them. It means that if a student can solve more proportion problem of mathematics textbooks then he can solve more proportional reasoning problem, and he have same ability in reverse order. In detail, the problem solving ability level difference between students are small if they met similar problem in mathematics text book, and if they didn't met similar problem before then the differences are getting bigger.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.3
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• pp.273-288
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• 2019

This study focuses on understanding proportionality, in particular, what constitutes relational understanding of a:b=c:d, which is called proportional expression. The meanings of a:b=c:d are analyzed and some suggestions are offered for improving the teaching and learning of it. The equation a:b=c:d has three different meanings. First, it represents two different structures in one proportional situation. Second, it represents a common structure in two different proportional situations. Finally, it represents a number or a quantity underlying in different proportional situations. It is important to choose and use a unit flexibly to understand the first and the second meanings of a:b=c:d, Double strip diagram and double number line are useful to visualize the meanings of a:b=c:d. In addition, what a number or a quantity in the third meaning of a:b=c:d refers to in proportional situations should be emphasized in teaching and learning of a:b=c:d.