• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.5
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• pp.17-23
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• 2004

In this paper, we proposed a mixed algerian to improve decimal division speed. In the binary number system, nonrestoring algorithm has a smaller number of operation than restoring algorithm. In decimal number system however, the number of operations differs with respect to quotient values. Since one digit ranges 0 to 9 in decimal, the proposed mixed algerian employs both nonrestoring and restoring algorithm considering current partial remainder values. The proposed algorithm chooses either restoring or nonrestoring algerian based on the remainder values. The proposed algorithm improves computation speed substantially over a single algorithm decreasing the number of operations.

• Journal of Elementary Mathematics Education in Korea
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• v.17 no.1
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• pp.1-17
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• 2013

In this paper, firstly, 'value', 'vertices', 'height' are discussed, which are used in the multiple contexts. Then 'sketch', 'mental math', 'zero point oneth place/zero point zero oneth place/zero point zereo zero oneth place', 'number of place', 'natural number part/decimal part' are discussed, which are not used consistently. Finally, middle school mathematics terms 'distance', 'number line', 'the value of the expression' are discussed which are used in elementary school mathematics textbooks/workbooks. From these discussions, the following four suggestions are proposed as conclusions. First, as a mathematical term 'value' and 'distance' should be emphasized. As 'distance' is a middle school term, there is a need to consider the 'height' as 'the length of the line segment' instead of 'distance'. Second, 'number of place' which can be replaced with other suitable term, 'the value of the expression' including 'value of $20{\times}4$', 'natural number part/decimal part', 'vertex of pyramid/vertex of cone', 'mental math' should not be used. Third, there is a need to consider the use of 'mixed decimal' and 'proper decimal'. In addition, there is a need to expand the use of 'sketch'. Fourth, there is a need to consider the confirmation of 'number line' as an elementary school mathematics term. In addition, there is a need to consider to specify that 'decimal first place', 'decimal second place', 'decimal third place' can be used equivalently with 'zero point oneth place', 'zero point zero oneth place', 'zero point zereo zero oneth place' respectively.

• Journal of Educational Research in Mathematics
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• v.14 no.1
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• pp.1-17
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• 2004

According to the 7-th curriculum, irrational number should be introduced using repeating decimals in 8-th grade mathematics. To do so, the relation between rational numbers and repeating decimals such that a number is rational number if and only if it can be represented by a repeating decimal, should be examined closely Since this relation lacks clarity in some text books, irrational numbers have only slight relation with repeating decimals in those books. Furthermore, some text books introduce irrational numbers showing that $\sqrt{2}$ is not rational number, which is out of 7-th curriculum. On the other hand, if we use numeral 0 as a repetend, many results related to repeating decimals can be represented concisely. In particular, the treatments of order relation with repeating decimals in 8-th grade text books must be reconsidered.

• Journal of Elementary Mathematics Education in Korea
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• v.18 no.3
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• pp.425-439
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• 2014

The concept of a fraction as division is a core idea which serves as a axiom in the process of a extension of the natural number system to rational number system. Also, it has necessary position in elementary mathematics. Nevertheless, the timing and method of the introduction of this concept in Korean elementary math textbooks is not well established. In this thesis, I suggested a solution of a various topics which is related to this problem, that is, transforming improper fraction to mixed number, the usage of quotient as a term, explaining the algorithm of division of fraction, transforming fraction to decimal.

• Journal of Elementary Mathematics Education in Korea
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• v.14 no.2
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• pp.377-399
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• 2010

Mixed calculations involving fractions and decimals covered in the unit 6-Na in elementary school math class cause students difficulties, leading them make lots of errors. If students fail to understand temporarily or partly what the teacher taught or lose confidence and continue to have difficulty due to a lack of understanding and skills of algorithm, though they properly understand the concept and principle of the learning content, it should be resolved through intensive teaching. For students suffering from this problem, a correct diagnosis and appropriate treatment are required. Therefore, this study developed a feedback program after diagnosing students' errors through evaluating them in order to continuously assist them to fully understand contents regarding mixed calculations involving fractions and decimals.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.2
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• pp.215-238
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• 2016

The 2015 national revised curriculum was notified officially the last year. The intent and direction of the revision caused more or less change for mathematical contents to be taught and is expected to cause a considerable change in math class. In the level of elementary school mathematics, it turned that several contents were deleted or moved to the upper grades because the revision focused especially both on reducing students' burden of learning and on fostering the mathematical key competences. This study aims to examine the relevance of the change through investigation of the national curriculums for elementary school mathematics since 1946. The mathematical contents to be analyzed in this study were mixed calculation of natural numbers, mixed calculation of fractions and decimal fractions, position and direction of objects, are/hectare and ton, the range of numbers and estimating, surface and volume of cylinders, pattern and correspondence, and direct/inverse proportionality, which were changed in any aspect relative to 2009 national revised curriculum. Based on the results of these analyses, the discussion will provide some suggestions for setting the direction of elementary mathematics curriculum.

• School Mathematics
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• v.17 no.2
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• pp.157-178
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• 2015

The purpose of this study was to investigate the role of calculators as a cognitive tool rather than calculating tool in learning elementary school mathematics. The calculator activities on multiplying two numbers ending with 0s or two decimal fractions and mixed four operations were developed, and exploratory lessons with the activities were implemented to three 3rd graders and two 5th graders. The results were shown that calculators provided an alternative effective learning environment: students were able to use heuristic thinking, reason inductively and successfully investigate principles of mathematics through the pattern recognition. And finally, we discussed the heuristic method through utilizing calculators.

• Journal of the Korean Society for Library and Information Science
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• v.45 no.4
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• pp.309-326
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• 2011

There have been several milestones in the history of library classification but most of the schemes failed to meet the new challenges in the organisation of information. Dr. S. R. Ranganathan tried to revolutionise the whole thinking on classificatory approach, when he devised the Colon Classification (CC) in 1933. He developed the Colon Classification scheme with a sound theoretical background based on normative principles, Five laws of Library science, canons, etc. One important feature of CC is that, its use is not confined to information storage and retrieval alone. This paper presents an over view of different editions of the CC highlighting the salient features of the editions. Further the implication of Five Laws of Library Science has been described. The authors stressed that the features of such as greater hospitality, specificity and mixed notation has paved the way to design and develop the depth schedules on various micro level subjects and so far about 130 micro schedules have been published. The impressions by the leading LIS professionals during and after Ranganathan's time have been highlighted. The authors expressed the fear that when the library world would see the complete version of the seventh edition of CC? It may be due to lack of institutional support engaging in the research or financial constraints. The authors are of the opinion that any scheme to flourish needs a sound research body to bring out the revised editions as done in the case of Dewey Decimal Classification. The relevance of the CC in the contemporary world of Librarianship is discussed. Finally concludes that CC needs to be resuscitated as it is a precious national heritage; and still a force for the management of libraries.

• Korean Journal of Agricultural Science
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• v.8 no.2
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• pp.238-243
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• 1981

This experiment was carried out to study the availability of Korean peat as a main carrier material of rhizobial inoculant, using the alfalfa strain Rhizobium meliloti M 14 which was isolated in the previous report. Modification of powdered peat with calcium carbonate and other materials was studied; inoculation of the peat with culture broth, maturation of the mixture under different conditions, and survival of the strain in the peat culture was examined. The results obtained were as follows. 1. Peat produced in Pyongtak was highly acidic, pH 3.8, and addition of calcium carbonate by 14% was required for pH adjustment to 6.4. However the amount of calcium carbonate could be reduced by 4 to 8% when carbon or charcoal was mixed with the peat. 2. Viable number of the strain reached to $7-9{\times}10^9cells/g$ after 3 days, when inoculated with the culture broth of early stationary growth phase and matured in unsteriled peat of open trays; and the number in steriled peat was $1.1-6.2{\times}10^{10}cells/g$ after 5 days, when matured in closed bottles. 3. Survival of the strain was affected markedly by storage temperature, and positive effect of D-sorbitol on the viability was recognized at elevated temperatures, when added as an additional carbon source and moistening agent. Glycerol, sorbitol, or sodium lactate was utilized by the strain as a sole source of carbon, and the decimal reduction time of viable number in the peat culture was was found to be 8 to 9 weeks at $25^{\circ}C$ when these agents were added by 0.5%.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.18 no.1
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• pp.42-63
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• 1992

In order to investigate the effect of nonionic surfactants on the antimicrobial activity of preservatives in the presence and absence of p.0.E(20) Sorbitan fatty acid ester commonly used in cosmetics and pharmaceutical systems, these experiments were carried out by determining Minimum Inhibitory Concentration(MIC) values and MIC values of adaptation against test organisms. And also the inactivation of the preservative against each microorganism in formula added with various concentrations of P.0.E(20) Sorbitan monostearate were measured by use of a preservative death time curve The results obtained were as fort low : 1) Nonionic surfactant inactivated Methylparaben to varying extents, but not Imidazolidinyl urea. 2) A combined preservative system was inactivated to a little extent (range of 0.16-0.20% Conc.), no adaptation was observed for the 5. aureus ATCC 6538. Imidazolidinyl urea complex combined with Methylparaben had a broad antibacterial spectrum against the Gram(.) and the Gram(-) bacteria It was found that preservatives had a synergistic effect by use of mixed form of preservatives, 3) In formula preserved with 0.2% Methylparaben containing 0.5, 1.0 and 2.0% P.0.E(20) Sorbitan monostearate, E. coli ATCC 10s36 and P. aeruginosa NCTC 10490 died quickly within in 2hr 4) However, from Fig.5, S. aereus ATCC 6538 died more slowly within increasing surfactant concentration and the D-values(Decimal reduction time) were 5.2, 8 and 14 hr. for samples containing 0.5, 1 0 and 2.0% P 0. E(20) Sorbitan monostearate, respectively. 5) In the case of Methylparaben, no adaptation for the E. coli ATCC 10536 6) All of the nonionic surfactant, p.0. E(20) Sorbitan fatty acid ester used in the experiments decreased the effectiveness of Methylparaben, but not of Imidazolidinyl urea.