• Communications of Mathematical Education
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• v.36 no.4
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• pp.589-610
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• 2022

This study aimed to derive pedagogical implications by comparing and analyzing how the concept of pi is taught in 10 different elementary mathematics textbooks, which are scheduled to be applied from 2023. We developed a textbook analysis framework by previous studies on the concept of pi and the teaching of pi, and analyzed in terms of three instructional elements (i.e. inferring conceptsof pi, understanding properties of pi, and applying relationships). We derived the need to emphasize various contexts for estimation of pi, presentation of problem situations that provide motivation to actually measure diameters and circumferences, providing an opportunity to explore the properties of measurement, and an experience the flexibility of selecting an approximate value of pi. Based on the above conclusions and pedagogical implications through the research results., we suggested ways to teach the concept of pi in elementary mathematics and improvement points for developing textbooks focusing on the context of introduction of pi and the use of technological tools.

• Journal of Korean Medical classics
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• v.29 no.2
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• pp.165-176
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• 2016

Objectives : This study was done to investigate the formation process of the 'The Spleen controls the blood(脾統血)' concept, to clarify what this concept means and the mechanism of its physiology. Methods : Contents including 'Controlling blood(統血)' and 'Binding blood(攝血)' were searched and analyzed in medical classics. Previous researches were applied. Results & Conclusions : The concept of 'Controlling blood' could be defined as the control of blood movement. This means that it sends blood to where it's needed, and inhibits flow from where it's excessive. 'The Spleen controls the blood' was not used as a physiologic term in early books like Huangdineijing(黃帝內經). It was first used in the 13C, then widely after the 16C. The mechanism of 'Controlling blood' could be classified as the function of 'Production', 'Distribution', and 'Adjustment' of blood. 'Production' of blood can reduce blood fever(血熱) and blood stasis(瘀血), and prevent bleeding. 'Distribution' of blood can reduce the symptoms raised by lack of blood in the five viscera and body. 'Adjustment' of blood means maintaining homeostasis and stability of the human body. Pi can adjust blood flow and prevent blood from being imbalanced.

• Journal of the Chungcheong Mathematical Society
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• v.13 no.1
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• pp.87-94
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• 2000

In this paper we shall de ne a concept of ${\pi}_1$-category for a map relative to a subset which is a generalization of both the category for a map and the ${\pi}_1$-category of a space, and study some properties of the ${\pi}_1$-category for a map relative to a subset.

• Bulletin of the Korean Mathematical Society
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• v.44 no.4
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• pp.641-649
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• 2007

We in this note introduce a concept, so called ${\pi}-Armendariz$ ring, that is a generalization of both Armendariz rings and 2-primal rings. We first observe the basic properties of ${\pi}-Armendariz$ rings, constructing typical examples. We next extend the class of ${\pi}-Armendariz$ rings, through various ring extensions.

• Journal of Korea Entertainment Industry Association
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• v.14 no.4
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• pp.199-209
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• 2020

"Positive Influence(PI)" of popular star has recently emerged as a social concern, but the lack of prior research has led to confusion over its concept and range of activity. On this point, this study carried out to lay the groundwork for discussions on the systematization of related theories, focused on identifying the current situations by analyzing articles for 15 months from January 2019 to March 2020 when related reports were in full swing. As a result of the analysis of the remarks from the entertainers mentioned in the articles, they were not clearly aware of the concept while doing good deeds under the name of PI in light of the study outcome by Aegean and Singer(2013). The motivations for good deed were classified into six types, including difficulty empathy, fandom reward, participation urge, nidana emphasis, experience subjugation, and memory evocation in the order of frequency of cases. Specific behaviors of PI were followed by donations of money and valuables for 54.4 percent, participation of social agendas for 14.0 percent, volunteering for 13.2 percent, joining campaign for 11.4 percent, other good deeds for 4.0 percent, and philanthropy for 3.0 percent. In occupational analysis, the concentration of donations was also evident. Their activities in the fields of human rights sensitivity, environmental protection and self-management, which are expected to have great effects with their influence, have been extremely poor. The results of the study first require academia to establish a interdisciplinary concept for PI. It also suggests that entertainers and their agencies should take far more strategic approach to evolve the PI event in a way that utilizes the advantages of each job group, such as actors, singers and comedians, and expands the diversity of areas.

• Korean Journal of Mathematics
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• v.9 no.2
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• pp.123-128
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• 2001

Given a homomorphism ${\Pi}:X{\rightarrow}Y$, with Y minimal, we will introduce the concept of a relative (to ${\Pi}$) F-regular relation which generalize the notions of F-proximality, F-regularity and relative F-proximality, and will study its properties.

• Bulletin of the Korean Mathematical Society
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• v.50 no.6
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• pp.1887-1903
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• 2013

We continue the study of McCoy condition to analyze zero-dividing polynomials for the constant annihilators in the ideals generated by the coefficients. In the process we introduce the concept of ideal-${\pi}$-McCoy rings, extending known results related to McCoy condition. It is shown that the class of ideal-${\pi}$-McCoy rings contains both strongly McCoy rings whose non-regular polynomials are nilpotent and 2-primal rings. We also investigate relations between the ideal-${\pi}$-McCoy property and other standard ring theoretic properties. Moreover we extend the class of ideal-${\pi}$-McCoy rings by examining various sorts of ordinary ring extensions.

• Bulletin of the Korean Mathematical Society
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• v.41 no.3
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• pp.393-401
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• 2004

In this paper, we apply the concept of the group \ulcorner(X,A) of self pair homotopy equivalences of a CW-pair (X, A) to the Postnikov system. By using a short exact sequence related to the group of self pair homotopy equivalences, we obtain the following result: for any Postnikov section X$\sub$n/ of a CW-complex X, the group \ulcorner(X$\sub$n/, A) of self pair homotopy equivalences on the pair (X$\sub$n/, X) is isomorphic to the group \ulcorner(X) of self homotopy equivalences on X. As a corollary, we have, \ulcorner(K($\pi$, n), M($\pi$, n)) ≡ \ulcorner(M($\pi$, n)) for each n$\pi$1, where K($\pi$,n) is an Eilenberg-Mclane space and M($\pi$,n) is a Moore space.

• Journal of the Korean Mathematical Society
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• v.47 no.6
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• pp.1269-1282
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• 2010

We in this note consider a new concept, so called $\pi$-McCoy, which unifies McCoy rings and IFP rings. The classes of McCoy rings and IFP rings do not contain full matrix rings and upper (lower) triangular matrix rings, but the class of $\pi$-McCoy rings contain upper (lower) triangular matrix rings and many kinds of full matrix rings. We first study the basic structure of $\pi$-McCoy rings, observing the relations among $\pi$-McCoy rings, Abelian rings, 2-primal rings, directly finite rings, and ($\pi-$)regular rings. It is proved that the n by n full matrix rings ($n\geq2$) over reduced rings are not $\pi$-McCoy, finding $\pi$-McCoy matrix rings over non-reduced rings. It is shown that the $\pi$-McCoyness is preserved by polynomial rings (when they are of bounded index of nilpotency) and classical quotient rings. Several kinds of extensions of $\pi$-McCoy rings are also examined.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2765-2768
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• 2003

The PI controller has many trial-and-error steps for gain design. This paper proposes a new design concept. In this method, a degree of stability and Kharitonov theory are applied and the controller gain is directly expressed by system parameters and current controller's bandwidth. Simulation results for permanent magnetic synchronous motor(PMSM) driving systems confirm the validity of proposed method.