• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.877-879
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• 1993

In this paper, the voltage control is applied to the adjustable speed operation of BLDC motor with the trapezoidal back emf waveform. Torque chrateristics of BLDC are investigated through Fourier analysis when the pulse width modulation inverter is applied. Also, this paper consisders the theoretical problem of eliminating some harmonic components in inverter output waveforms, which, in turn, allows to remove some ripple components. Numerical technique is applied to solve the transcendental equations of the problem by the computer.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1227-1229
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• 2003

Kojima Lake in Okayama prefecture is a freshing reservoir constructed adjacent to the oldest reclaimed land in Japan. This lake has a serious water quality problem because two urban rivers are flowing into it. In the present study, unsupervised classification was performed at intervals of several years using Landsat MSS data in the past 15 years. After geometric correction of these data, MSS data corresponding geographically to the field observation data were extracted and subjected to the multivariate analysis. Water quality distribution in the lake was estimated using the regression equation obtained as a result. In addition, two - dimensional and three-dimensional numerical simulations were performed and compared with the distribution obtained from the satellite images. Behavior of the reservoir flows is complicated and water quality distribution varies greatly with the flows. Here, I report the results of analysis on three factors, field observation, numerical simulation and satellite images.

• The Mathematical Education
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• v.42 no.4
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• pp.465-480
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• 2003

The main purpose of this work is to propose programs of mathematics education and mathematics history courses for the department of mathematics education of teacher training universities. Foundation of Mathematics Education, Mathematics Teaching and Learning Theories, Mathematics Problem Solving, Analysis and Evaluation of Mathematics Teaching Materials and Mathematics History are discussed in this article.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.593-599
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• 2005

This paper is concerned with the vibration analysis of a rectangular plate with a rectangular hole. Even though there have been many methods developed for the addressed problem, they suffer from computational time. In this paper, we developed a new methodology called Independent Coordinate Coupling Method which can couple two independent coordinate systems for the entire plate domain and the hole. By matching the deflection condition imposed on the expressions, the relationship between the global axes and the local axes is derived. This formula is then used for the calculation of the eigenvalue problem. The numerical results show the efficacy of the proposed method.

• Language and Information
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• v.18 no.2
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• pp.123-140
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• 2014

The aim of this paper is twofold: to identify two types of even if concessive conditionals, standing-ifs and introduced-ifs (Bennett 1982) in terms of whether the truth of the consequent is 'entailed' (the consequent-entailment problem in terms of Lycan 2001); and to analyze these two types of concessive conditionals in a compositional way. Here we argue that, following Guerzoni and Lim (2007), even if conditionals can be analyzed as the cases where even gets its focus in conditionals. We also argue that the consequent-entailment problem can be accounted for in a compositional way if we identify the focus as well as the scope of even in conditionals correctly. We further argue that the analysis presented in this paper supports the scope theory of even, among two theories of even previously proposed in various works. We also consider the possibility where concessive conditionals without even can be analyzed as an extension of the analysis proposed in this paper.

• Structural Engineering and Mechanics
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• v.7 no.6
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• pp.561-573
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• 1999

A $C^*$-convergence algorithm for finite element analysis has been proposed by Bigdeli and Kelly (1997) and elements for the first three levels applied to planar elasticity have been defined. The fourth level element for the new family is described in this paper and the rate of convergence for the $C^*$-convergence algorithm is investigated numerically. The new family adds derivatives of displacements as nodal variables and the number of nodes and elements can therefore be kept constant during refinement. A problem exists on interfaces where the derivatives are required to be discontinuous. This problem is addressed for curved boundaries and a procedure is suggested to resolve the excessive interelement continuity which occurs.

• Journal of the Optical Society of Korea
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• v.17 no.6
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• pp.506-512
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• 2013

Recently, the color separation issue of wide-spreading white LEDs has attracted attention due to their wide applicability as light sources in direct-lit LCD backlights. These wide-spreading LED packages usually consist of LED chips, a color-conversion phosphor layer, and a light-shaping lens. The technical aspect of this color issue was related to a method for balancing the yellow spectral component emitting from phosphors with respect to the blue one from the LED chip as a function of viewing angle. In this study, we suggested an approach for carrying out quantitative analysis for the color separation problem occurring in wide-spreading LED packages by optical simulation. In addition, the effect of an internal scattering layer on the color uniformity was investigated, which may be considered as a potential solution for this problem.

• Cross-Cultural Studies
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• v.33
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• pp.359-384
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• 2013

There is linguistic phenomenon that Korean syllable, morpheme and word are substituted with Chinese Character. These phenomenon is called Chinese Character Borrowing, the Chinese character used here is called Borrowed Chinese Character. Whereas borrowing Chinese character in Chinese is used for borrowing only sound for different word, borrowing Chinese character in Korean is used for assigning new meaning. Hence, by borrowing Chinese character in Korean, a syllable which had no meaning originally get new meaning, morpheme and word meaning has changed. At advertisement and campaign, Chinese Character Borrowing has lots of linguistical advantage such as visual immediacy, effectiveness of meaning expression. However, there are number of cases found that violate grammar rule and word constitution practice by Chinese Character Borrowing. For this reason, Chinese Character Borrowing has the problem polluting Korean along with another foreign words. Thus, this paper focus on study Chinese Character Borrowing phenomenon in Korean, and analysis its effectiveness and impact in Korean. In addition, analysis the problem of Borrowed chinese Character, and suggestion several alternative for right use of Korean is followed.

• Journal for History of Mathematics
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• v.32 no.2
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• pp.47-59
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• 2019

Hua Loo-Keng(华罗庚, 1910-1985) is one of well-known prominent Chinese mathematicians. While Waring problem is one of his research interests, he made lots of contributions on various mathematical fields including skew fields, geometry of matrices, harmonic analysis, partial differential equations and even numerical analysis and applied mathematics, as well as number theory. He also had devoted his last 20 years to the popularization of mathematics in China. We look at his personal and mathematical life, and consider the meaning of his activity of popularizing mathematics from the cultural perspective to understand the recent rapid developments of China in sciences including mathematics and artificial intelligence.

• Coupled systems mechanics
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• v.8 no.3
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• pp.259-271
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• 2019

This paper presents forced vibration analysis of sandwich deep beams made of functionally graded material (FGM) in face layers and a porous material in core layer. The FGM sandwich deep beam is subjected to a harmonic dynamic load. The FGM in the face layer is graded though the layer thickness. In order to get more realistic result for the deep beam problem, the plane solid continua is used in the modeling of The FGM sandwich deep beam. The equations of the problem are derived based the Hamilton procedure and solved by using the finite element method. The novelty in this paper is to investigate the dynamic responses of sandwich deep beams made of FGM and porous material by using the plane solid continua. In the numerical results, the effects of different material distributions, porosity coefficient, geometric and dynamic parameters on the dynamic responses of the FGM sandwich deep beam are investigated and discussed.