• Communications of Mathematical Education
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• v.37 no.1
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• pp.47-64
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• 2023

The current elementary mathematics curriculum does not include intensive quantity. However, other subjects also deal with intensive quantity. In order to find a solution to this problem from a pedagogical point of view, the curriculum of mathematics, science, social studies, and elementary textbooks were compared and analyzed, focusing on intensive quantity. As a result of the analysis, the learning contents of intensive quantity were not explicitly presented or the term was not used in the elementary mathematics curriculum. However, intensive quantity was used as a material of activity and word problems in elementary mathematics textbooks. In science and social studies, it was also found that the learning order and content did not match, such as calculating the intensive quantity. For effective learning, it is necessary to consider presenting intensive quantity in elementary mathematics, and to be careful in the composition of learning order and content.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.1
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• pp.1-15
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• 2016

In this paper, the following three issues are discussed in connection with intensive quantities. (1) Is there any relationship among intensive quantity, per unit quantity, and ratio? (2) Which intensive quantities obtained by two same extensive quantities are handled? And How are they handled? (3) Which intensive quantities obtained by two different extensive quantities are handled? And How are they handled? Based on the results of this discussions, three implications are suggested as conclusions to explore the direction for the development of handling intensive quantities in elementary math textbooks and workbooks. Firstly, it is necessary to systematize the systemize a series of processes to handle intensive quantities. There is a need to rethink to use terms like speed and velocity before handling the ratio. Secondly, there is a need to rethink the definition of intensive quantities which have the particular names. For example, it is necessary to rethink using average distance in the definition of speed and the average population in the definition of density of population. Thirdly, it is necessary to consider the limiting the kinds of intensive quantities obtained by two same extensive quantities handled in the elementary math. There is a need to set limit to them which are used in daily life, and there is a need to rethink to use them which are used in the specialized area. There is a need to rethink the using hitting ratio in the form of %.

• Journal for History of Mathematics
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• v.23 no.3
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• pp.121-140
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• 2010

This study presents one universal mean formula of implicate quantity for speed, temperature, consistency, density, unit cost, and the national income per person in order to avoid the inconvenience of applying different formulas for each one of them. This work is done by using the principle of lever and was led to the formula of two implicate quantity, $M=\frac{x_1f_1+x_2f_2}{f_1+f_2}$, and to help the understanding of relationships in this formula. The value of ratio of fraction cannot be added but it shows that it can be calculated depending on the size of the ratio. It is intended to solve multiple additions with one formula which is the expansion of the mean formula of implicate quantity. $M=\frac{x_1f_1+x_2f_2+{\cdots}+x_nf_n}{N}$, where $f_1+f_2+{\cdots}+f_n=N$. For this reason, this mean formula will be able to help in physics as well as many other different fields in solving complication of structures.

• The Korean Journal of Applied Statistics
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• v.13 no.1
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• pp.55-70
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• 2000

본 논문에서는 내포오차성분을 가지는 패널회귀모형에서 회귀계수에 대하여 다양한 추정량들을 유도하고, 추정량들의 효율성을 모의실험을 통하여 평균제곱오차의 기준에서 비교하였다. 모의실험 결과, 제안된 FGLS 추정량들은 GLS추정량과 효율성에서 서로 큰 차이를 보이지 않았으며, 계산상 더욱 복잡한 ML, REML 추정량 및 MIVQUE와 거의 비슷한 효율성을 보여주었다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1995.10a
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• pp.51-56
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• 1995

일방향 흐름에 표면파가 중복하여 작용할 때 해저면 마찰력의 증가로 토사이동량의 증대가 예상된다. 표면파는 왕복운동 특성을 갖고 있으며, 유속과 해저전단력간의 위상차와 해저잔단력과 토사이동발생 시각간의 위상차가 존재하기 때문에 토사이동량 산정에 많은 어려움이 따른다. 그러나 이렇게 복잡한 현상이 내포되어 있음에도 불구하고 일반적인 기법으로 하천 토사이동량 산정식을 수정하거나 비례상수를 재조정하여 파와 해류에 의한 토사이동량을 산정해 왔다. (중략)

• Culinary science and hospitality research
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• v.7 no.3
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• pp.179-191
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• 2001

The effects of whole wheat flour on the Rheological Properties of dough gassing power of yeast S.cerevisiae and breadmaking properties were studied. The blending ratios of whole wheat flour to bread making flour were 0, 25, 50, 75 and water absorption in the farinography increasedlinerly from 62.5%in 100% bread making flour and 77.5% in 100% whole wheat flour. The hardness and cohesiveness of dough prepared with optimum moisture content was constant regardless of the blending ratio of whole wheat flour. whole wheat flour had no effect on the total gas production or the internal gas content in the dough at a constant moisture level but had detrimental effect on the loaf volume. In a dough at the optimum moisture level, whole wheat flour increased the two former parameters sensory evaluation indicated that the replacement in the range of 25 to 50% with whole wheat flour at the optimum moisture level was acceptable

• Journal of Educational Research in Mathematics
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• v.20 no.4
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• pp.445-458
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• 2010

This study intends to investigate the process of the development of quantity concept and how to deal with the quantity calculus in elementary school, and to find out the implication for improving the curriculum and mathematics textbooks of Korea. There had been the binary Greek categories of discrete number and continuous magnitude in quantity concept, but by the Stevin's introduction of decimal, the unification of these notions became complete. As a result of analyzing of the curriculum and mathematics textbooks of Korea, there is a tendency to disregard the teaching of quantity and its calculus compared to the other countries. Especially multiplication and division of quantity is seldom treated in elementary mathematics textbooks. So these should be reconsidered in order to seek the direction for improvement of mathematic teaching. And Korea's textbooks need the emphasis on the quantity calculus and on constructing quantity concept.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1127-1131
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• 2004

최근에 재해영향평가 등에서 많이 채택하고 있는 Huff의 4분위법에 의한 강우의 시간분포를 통한 유출량 산정은 도시화지역 등에서 유출량에 내한 관측기록이 없어서 적절한 검정이 불가능한 실정이다. 따라서 산정된 계획홍수량에 의해 설계되는 수공구조물의 경제성 또는 안전성의 정도를 파악하지 못하고 실무에 반영되는 문제를 내포하고 있다. 본 연구에서는 서울지역 최근 29개년간의 년 최대 강우관측자료에 대하여 각각을 Huff의 4분위법에 의한 10분 간격으로 시간분포고, 실제 관측 강우의 경우 10분 간격으로 판독하여 도시유출모형인 SWMM을 이용하여 유출량을 산정하고 결과를 비교하였다. 또한 각각에 대하여 유출량을 빈도해석하여 비교한 결과 강우의 시간분포간격이 짧은 경우 국내적용 Huff분포는 실강우분포에 의한 유출량보다 크게 산정되는 것으로 나타났다.

• The Korean Journal of Applied Statistics
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• v.14 no.1
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• pp.13-24
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• 2001

In this paper, we investigated mean estimation methods in two-phase sampling. Under the fixed expected cost we reviewed the optimal sample sizes, minimum variances and approximate unbiased variance estimators for usual ratio estimator, stratified sample mean with proportional allocation and Rao's allocation of the second phase sample. Also we proposed combined ratio estimator, which uses both ratio estimation and stratification and derived optimal sample size, minimum variance and unbiased variance estimator. Through a limited simulation study, we compared estimators by design effects and came to know that ratio estimator is more efficient than stratified sample mean in some cases and inefficient in the other cases, but combined ratio estimator is more efficient than others in most cases.

• Journal of Educational Research in Mathematics
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• v.26 no.3
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• pp.333-354
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• 2016

The aim of the present study is twofold. One is to confirm a hypothesis that a student's rate concept influences her conceiving change of a function in the view of rate of change and the other is to build up foundations for understanding the transition process from her rate concept to the concept of rate of change when she investigates the change of concentration as an intensive quantity. We explored how three participating high school students recognized and expressed change of given functions by using their rate concept as a conceptual tool. The result indicates that a change in students' rate concept might have an effect on understanding how function values change in term of rate of change. We also expect that it could be a catalyst for further research for clarifying the relationship between students' rate concept and their development of a concept of rate of change as a foundation for learning calculus.