• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.149-154
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• 1996

We propose the concept of incident angle of complex number and analyze planar optical waveguides by applying the concept. The incident angle of complex number is concerned with the modeling of prism-gap-waveguide structures. It is shown that, when optical waveguides are analyzed by use of the transfer matrix method, the proposed concept enable us to find solutions faster and more accurately than ghatak's method which introduces the leaky structure.

• The Mathematical Education
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• v.61 no.2
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• pp.305-322
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• 2022

Angle has a variety of aspects, such as figure, measurement, and rotation, but is mainly introduced from a figure perspective and a quantitative perspective of the angle is also partially experienced in the elementary mathematics textbooks. The purpose of this study was to examine how the angle concept introduction and development pattern in elementary school mathematics textbooks are linked or changed in middle school mathematics textbooks, and based on this, was to get the direction of writing math textbooks and implications for guidance. To this end, 57 math textbooks for the first grade of middle school were collected from the first to the 2015 revised curriculum. As a result of the study, it was found that middle school textbooks had a greater dynamic aspect of each than elementary school textbooks, and the proportion of quantitative attributes of angle was higher in addition to qualitative and relational attributes. In other words, the concept of angle in middle school textbooks is presented in a more multifaceted and complex form than in elementary school textbooks. Finally, matters that require consensus within elementary, secondary, and secondary schools were also proposed, such as the use of visual expression or symbol, such as the use of arrows and dots, and the use of mathematical terms such as vertex of angle and side of angle.

• School Mathematics
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• v.3 no.1
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• pp.25-44
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• 2001

The purpose of the study is to investigate multifaced aspects of angle concepts and the developments of angle concept and to examine textbooks in relation to above investigation. In this study, we obtain the following results. First, angle concepts have static and dynamic aspects and develop situated angle concepts, contextual angle concepts, abstract angle concepts, through formal angle concepts. Second, our textbooks emphasize abstract angle concepts and formal angle concepts but lack situated angle concepts and contextual angle concepts.

• Journal for History of Mathematics
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• v.18 no.4
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• pp.85-100
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• 2005

In recent papers (Pak et al., Pak and Kim), it was suggested to positively use the history of mathematics for the education of mathematics and discussed the determining problem of the order of instruction in mathematics. There are three kinds of order of instruction - historical order, theoretical organization, lecturing organization. Lecturing organization order is a combination of historical order and theoretical organization order. It basically depends on his or her own value of education of each teacher. The present paper considers a concrete problem determining the order of instruction for the concept of angle. Since the concept of angle is defined in relation to figures, we have to solve the determining problem of the order of instruction for the concept of figure. In order to do this, we first investigate a historical order of the concept of figure by reviewing it in the history of mathematics. And then we introduce a theoretical organization order of the concept of figure. From these basic data we establish a lecturing organization order of the concept of figure from the viewpoint of problem-solving. According to this order we finally develop the concept of angle and a related global property which leads to the so-called Gauss-Bonnet theorem.

• School Mathematics
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• v.18 no.2
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• pp.425-440
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• 2016

Concept images play an important role in the acquisition of mathematical concept. However, sometimes concept images are derivatives of student's misconceptions. In addition, students always learn concept images despite teachers' efforts to teach concept definitions. Therefore, teachers need to know about all the concept images of a particular concept. This study aimed to analyze the concept image that students have about the triangle when they have already learned about the triangle in school. It was found that some students have different concept images about the triangle between Semo. Moreover, many students have misconceptions about vertices, sides, and angles. In particular, students think Gak denotes a side, although it means angle. Based on these results, I suggest that the curriculum and textbook require improvement.

• Journal of Power Electronics
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• v.8 no.4
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• pp.332-344
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• 2008

High frequency AC (HFAC) power distribution systems delivering power through a high frequency AC link with sinusoidal voltage have the advantages of simple structure and high efficiency. In a multiple module system, where multiple resonant inverters are paralleled to the high frequency AC bus through connection inductors, it is necessary for the output voltage phase angles of the inverters be controlled so that the circulating current among the inverters be minimized. However, the phase angle of the resonant inverters output voltage can not be controlled with conventional phase shift modulation or pulse width modulation. The phase angle is a function of both the phase of the gating signals and the impedance of the resonant tank. In this paper, we proposed a pulse phase modulation (PPM) concept for the resonant inverters, so that the phase angle of the output voltage can be regulated. The PPM can be used to minimize the circulating current between the resonant inverters. The mechanisms of the phase angle control and the PPM were explained. The small signal model of a PPM controlled half-bridge resonant inverter was analyzed. The concept was verified in a half bridge resonant inverter with a series-parallel resonant tank. An HFAC power distribution system with two resonant inverters connected in parallel to a 500kHz, 28V AC bus was presented to demonstrate the applicability of the concept in a high frequency power distribution system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.777-782
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• 2002

The range profile is easily obtainable and promising feature vector in the aspect of real-time radar target recognition system. However, the range profile is highly dependent on a aspect angle of a target and this dependence make it difficult the recognition over wide-angular region. In this paper, we propose the classifier with subclass concept in order to solve this dependence problem. Recognition results using six aircraft models measured at compact range facility are presented to show the effectiveness of this proposed classifier over wide-angular region.

• Journal of the Korean Society for Library and Information Science
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• v.45 no.4
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• pp.287-295
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• 2011

The Five Laws of Library Science was introduced into Japan in 1935. After World War II, it was widely disseminated among young librarians by the education for librarianship developed in the 1950's. Its concept, "Books for All," met a serious opposition from local authorities based on their long continued concept of "preservation." After they realized that people eagerly use local libraries, they interpreted that the duty of public library was "lending books." They introduced "Privatization" of libraries into quite a few local libraries in order to save money. For overcoming problems, it is important to disseminate the library concept among the public, the assembly members and government officials planning to change their attitude of disregarding libraries. As the fundamental library philosophy, the Five Laws of Library Science is important. In the commentary of the Five Laws written by the present writer, he included an illustration of triangle pyramid showing the structure of the Five Laws. He included here the spiral of study on the library and the library science, based on the Section 814 of the Five Laws. He welcomes discussions on his Japanese angle from different viewpoints in order to develop further understanding of the Five Laws.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.138-147
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• 1999

For autonomous navigation, a legged robot should be able to walk over irregular terrain and adapt itself to variation of supporting surface. Walking through slope is one of the typical tasks for such case. Robot needs not only to change foot trajectory but also to adjust its configuration to the slope angle for maintaining stability against gravity. This paper suggests such adaptation algorithm for stable walking which uses feedback of reaction forces at feet. Adjusting algorithm of foot trajectory was studied with the estimated angel of slope without visual feedback. A concept of virtual slope angle was introduced to adjust body configuration against slope change of the supporting terrain. Regeneration of foot trajectory also used this concept for maintaining its stable walking against unexpected landing point.

• The Mathematical Education
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• v.50 no.1
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• pp.27-40
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• 2011

The purpose of this paper is to analyze and discuss the viewpoint dealing with the fundamental figures-point, line segment, and angle-of elementary school teachers. In fact, our main subjects in this article are as follows; how do elementary school teachers deal with the fundamental figures?, what is the general notion about the fundamental figures of elementary school teachers? Our such subjects come from the survey results about the 'fundamental figures in J. A. Ko(2009); the elementary school students have a tendency to regard the fundamental figures as not mathematical figures. In this article, we discuss mainly the meta-cognitive shift in the transform of notion, for example, from 'congruent' concept to 'equal' concept, about the fundamental figures.