• Journal of the Korean School Mathematics Society
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• v.20 no.4
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• pp.495-519
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• 2017

The purpose of this study is to analyze the concept of the real number e and to investigate the understanding of pre-service teachers about the real number e. 28 pre-service teachers were asked to take a test based on the various ideas of the real number e and 8 pre-service teachers were interviewed. The results of this study are as follows. First, a large number of pre-service teachers couldn't recognize relation between the formal definition and the representations of the real number e. Secondly, pre-service teachers judged appropriately for the irrationality and the construction impossibility of the real number e, but they couldn't provide reasonable evidence. Lastly, pre-service teachers understood the continuous compounding context and exponential function context of the real number e, but they had a difficulty in understanding the geometric context and natural logarithm context of the real number e.

• Communications of Mathematical Education
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• v.25 no.2
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• pp.323-339
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• 2011

The expansion of exponential law as the law of calculation of integer numbers can be a good material for the students to experience an extended configuration which is based on an algebraic principle of the performance of equivalent forms. While current textbooks described that exponential law can be expanded from natural number to integer, rational number and real number, most teachers force students to accept intuitively that the exponential law is valid although exponent is expanded into real number. However most teachers overlook explaining the value of exponent of rational number or exponent of irrational number so most students have a lot of questions whether this value is a rational number or a irrational number. Related to students' questions, most teacher said that it is out of the current curriculum and students will learn it after going to college instead of detailed answers. In this paper, we will present several examples and the values about irrational exponents of a positive rational and irrational exponents of a positive irrational number, and study the recognition and fallacy of would-be teachers about the cases of irrational exponents of a positive rational and irrational exponents of a positive irrational number at the expansion of exponential law.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.114-117
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• 2002

현재 개발 중에 있는 비파괴 검사법인 Tapping Sound Analysis 의 실험적 검증을 위한 연구를 수행하였다. 손상이 없는 복합재료 구조물과 손상이 있는 복합재료 구조물에 대한 타격 실험을 통해 타격음과 타격력을 측정하여 비교하였다. Wavelet packet transform에 근거한 특성 추출법을 이용하여 타격음으로부터 손상 판단을 위한 특성을 추출하였다. 손상이 없는 구조물과 손상이 있는 구조물의 특성을 비교하기 위해, 특성 지수를 정의하였다. 정의된 특성 지수를 이용하여 손상이 없는 구조물과 손상이 있는 구조물의 타격음의 차이를 하나의 실수로 표현하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.2
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• pp.97-103
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• 2010

In this paper, we propose a new digital watermarking technique. The main idea of the proposed algorithm relies on the assumption that any real number can be expressed as a summation of the exponential form with base of 2 and if only consider the first few summations some numbers can be expressed in the same form. Therefore, we can be sure that some amount of changes does not affect the first few summations. The algorithm decomposes a host image in wavelet domain and intensity of the significant wavelet coefficient is expressed in exponential form with base of 2. Multiple barcode watermarks are then embedded by modifying the parity of the exponent. The proposed scheme is semi-blind and also offers either objective or subjective deteew su as well. From extracted watermarks, more accurate watermark is obtained by merging technique as a final watermark. As a simulation result, the proposed algorithm could resist most cases of salt and pepper noise, Gaussian noise and JPEG compression.

• The Korean Journal of Financial Management
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• v.19 no.2
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• pp.159-185
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• 2002

한 시계열이 비정상적과정에 의해 생성될 때 이 시계열의 정상성을 확보하기 위하여 시계열의 차분을 수행한다. 이 시계열에 I(1)을 적용하여도 정상적과정이 되지 못하는 경우가 존재하고 있다. 그러면 이 시계열은 과도한 차분과정을 거치게 된다. 따라서 차분모수 d는 0

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.4
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• pp.398-402
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• 2014

A generalized trigonometric fuzzy set is a generalization of a trigonometric fuzzy number. Zadeh([7]) defines the probability of the fuzzy event using the probability. We define the normal and exponential fuzzy probability on $\mathbb{R}$ using the normal and exponential distribution, respectively, and we calculate the normal and exponential fuzzy probability for generalized trigonometric fuzzy sets.

• Korean Journal of Medicinal Crop Science
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• v.9 no.4
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• pp.301-309
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• 2001

This study was conducted to provide the basic information on safflower collections and to identify the variations which could be utilized in safflower breeding programs. The agronomic characteristics was used to clarify the genetic relationships among safflower collections and to classify them into distint genetic groups. There were 21 early maturing collections with less than 80 days in number of days from planting to flowering. The number of primary and secondary branches ranged ${3.8{\sim}14.8\;and\;0{\sim}26.9}$, respectively, and two collections, IT201434 and IT202723, were found to be high branch types. The 101 safflower collections were classified into 11 groups based on the complete linkage cluster analysis using agronomic characteristics. The I, II, III, IV, IX, X and ? groups included the 25%, 33%, 14%, 8%, 2%, 1% and 1% of the collections, respectively. All the collections in the group III were Korean landraces. The collections in group X could be characterized as early emergence, late flowering and high yield components such as the number of capitula per plant, number of seeds per capitula and seed weight per plant. The number of capitula per plant and seed weight per plant, i.e., the two main yield components, had the highly significant positive correlations with stem diameter, number of the primary branches, number of the secondary branches, number of leaves and leaf length.

• Journal for History of Mathematics
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• v.32 no.3
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• pp.109-134
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• 2019

In order to improve the educational situation in which the natural number e and the natural logarithm are dealt with somewhat perfunctorily, this study explores the genetic process in which the natural logarithm and its base e occurred, and has an educational discussion based on that analysed process. Specifically, the study inquires into how the natural logarithm happened in relation to the quadrature of the hyperbolic curves through analysis and thought experimentation in mathematics history. Particularly, it sheds light on the role of e and the naturalness of the natural logarithm in terms of the introduction of the real number exponent. Also, this study discusses what the findings suggest educationally.

• Journal of IKEEE
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• v.14 no.2
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• pp.64-68
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• 2010

This paper proposes efficient log and exponent calculation methods using a dual phase instruction set without additional ALU unit for a mobile enviroment. Using the Dual Phase Instruction set, it extracts exponent and mantissa from expression of floating point and calculates 24bit single precision floating point of log approximation using the Taylor series expansion algorithm. And with dual phase instruction set, it reduces instruction excution cycles. The proposed Dual Phase architecture reduces the performance degradation and maintain smaller size.

• 전기의세계
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• v.21 no.4
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• pp.45-47
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• 1972

최근까지의 관습적인 예측으로보면 인간의 동력사용은 앞으로 수십년에 걸쳐 현재와 같은 비율로 지수함수적으로 증가할 것이며 이로 인해 당연히 전세계의 한정된 화석연료자원이 급속히 고갈되지 않을까 하는 우려가 제기된다. 그러므로 인간의 실수요에 대해 타당한 예측을 하는것이 우선적 문제인데, 이것은 세계인구수와 1년 1인당의 예상수요의 산출로 분류할 수 있다. 인구수에 관해서는 다음과 같은 낙관적인 견해가 있다. 즉 인구는 2,000년까지 현재의 비율(년간 2%)로 계속 증가하여 현 3.5*$10^{9}$에서 6.6*$10^{9}$ 이 될 것이나, 21세기중에는 일정한 수에 머무를 것이다. 동력의 1인당 실수요 평가에 있어서는 여러가지 요인을 고려해야 한다.