• Journal of Educational Research in Mathematics
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• v.18 no.1
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• pp.51-62
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• 2008

In the 7th-curriculum, only basic arithmetics of complex numbers have been taught. They are taught formally like literal manipulations. This paper analyzes mathematically essential relations between algebra of complex numbers and plane geometry. Historical analysis is also performed to find effective methods of teaching complex numbers in school mathematics. As a result, we can integrates this analysis with school mathematics by help of Viete's operations on right triangles. We conclude that teaching geometric interpretation of complex numbers is possible in school mathematics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.342-350
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• 2000

In this paper, the bit error performance for the reverse link of a synchronous direct sequence code division multiple access (DS-CDMA) system employing an imperfect power control scheme over a frequency selective Rayleigh fading channel is analyzed. The system capacity degradation due to power control error (PCE), which is approximated by a log-normally distributed random variable, is estimate as a function of a standard deviation of the PCE. In addition, the impact of the multipath intensity profile (MIP) shape and the number of resolvable paths on the performance of the synchronous transmission is investigated. To estimate the system capacity, the coded bit error performance is evaluated and compared with the conventional CDMA. It is found tat synchronous transmission has less sensitivity to imperfect power control and eases the power control requirements. In particular, as the decay constant $\delta$ of MIP increases, the synchronous transmission in the DS-CDMA reverse link results in a significant BER improvement over the asynchronous transmission even in the presence of imperfect power control. We further conclude that the capacity can be improved by employing the synchronous transmission.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.189-190
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• 2018

최근에는 여행에 대한 각종 정보가 많이 공유되는 추세이다. 최근 사람들은 소셜 네트워크 서비스를 이용 중이거나 웹 서핑을 하는 도중에 기억하고 싶어 하는 여행지를 단순히 캡처 해놓거나 메모장에 기록해둔다. 이러한 방법은 시간이 지나 많은 데이터가 쌓이면 관리하기 어렵다는 문제가 존재한다. 본 논문에서는 사용자의 편리를 고려하여 사진의 텍스트를 광학식 문자 판독을 활용하여 출력하고 게시 글 형태로 저장할 수 있게 개발하였다. 명소의 위치 또한 자동완성 위치 검색 라이브러리를 통하여 편리 저장이 가능하다. 위치 데이터를 통해 향후 사용자가 근접하고 있는 여행지 또한 제공해줄 수 있도록 구현하였다. 이를 위하여 웹을 통해서 이용할 수도 있으며 실시간 검색과 알림 이벤트를 위해 웹 주소 입력 없이도 앱을 실행할 수 있는 프로그래시브웹 앱을 구현하였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.6
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• pp.23-28
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• 1978

This paper describes a speech recognition system for ten isolated spoken digits. In this system, acoustic parameters such as zero crossing rate, log energy and three formant frequencies estimated by linear prediction method were extracted for classification and/or recognition purpose(s). The former two parameters were used for the classification of unvoiced consonants and the latter one for the recognition of vowels and voiced consonants. Promising recognition results were obtained in this experiment for ten digit utterances spoken by a male speaker.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.6
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• pp.93-97
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• 2000

This paper established the demand factor of elevator. For this purpose, it was analysed the operating pattern of elevator into power supply facility installed in the apartment. As a result, it is found that the simultaneous driving-rate of elevator peaked at September in a year and the average operation of 1 day recorded the 800 counts. Also, the peak-value of simultaneous driving-rate investigated about 40∼45%. Therefore, it was analysed that the demand factor of elevator are smaller than 10% by standard data.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05b
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• pp.973-979
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• 1995

콘크리트의 물리적 특성치인 크리이프, 건조수축, 탄성계수 및 포아슨비등은 배차조건, 부재의 크기, 양생 및 재하조건 등 많은 요소들의 영향을 받고있다. 특히 크리이프와 건조수축은 복잡한 시간의존성 특성(time-dependent properties)으로 인해 아직까지도 이 분야에 대한 연구가 계속되고 있다. 따라서 본 연구에서는 불확실성이 많은 콘크리트의 장기거동에 따른 물리적 특성규명을 위하여 재하재령을 변화(7, 28, 90, 180, 365일) 시키면서 크리이프, 탄성계수, 포아슨비등을 측정, 분석함으로써 콘크리트 장기거동 예측식을 제시하였으며, 이는 프리스트레스트 콘크리트 구조물에서의 시간에 따른 응력손실을 고려한 유효 프리스트레스 응력 산정 및 구조물의 건전성 평가에 실질적 도움을 줄 수 있을 것으로 판단된다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.2
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• pp.8-12
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• 1984

Algorithms for solving a set of nonlinear simultaneous equations, which is frequently required in problems of controlling nonlinear processes, are proposed. Here the equation variables are first parameterized and a recursive identification technique is utilized. The forms and characteristics of the resultant algorithms are vary similar to the Broyden's quasi-Newton method, but their derivations and final recursion equations are different. Our methods possess almost all the merits of the Broyden's and numerical comparisons show our methods to be more efficient and reliable for some difficult problems.

• The Transactions of the Korea Information Processing Society
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• v.2 no.2
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• pp.264-276
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• 1995

In this paper, a technique for eliminating conditional branches in the compilers for superscalar processors is presented. The technique consists of three major steps. The first step transforms conditional branches into equivalent expressions using algebraic laws. The second step searches all possible instruction sequences for those expressions using GSO of Granlund/Kenner. Finally an optimal sequence that has the least dynamic count for the target superscalar processor is selected from the GSO output. Experiment result shows that for each conditional branch is the input program matched by one of the optimization patterns, the proposed technique outperforms more than 25% speedup of execution time over the original code when the GNU C compiler and the SuperSPARC processor are used.

• Education of Primary School Mathematics
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• v.26 no.1
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• pp.45-63
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• 2023

The activity of finding rules is useful for enhancing the algebraic thinking of elementary school students. This study analyzed the pattern activities of a finding rules unit in 10 different government-authorized mathematics curricular materials for fourth graders aligned to the 2015 revised national mathematics curriculum. The analytic elements included three main activities: (a) activities of analyzing the structure of patterns, (b) activities of finding a specific term by finding a rule, and (c) activities of representing the rule. The three activities were mainly presented regarding growing numeric patterns, growing geometric patterns, and computational patterns. The activities of analyzing the structure of patterns were presented when dealing mainly with growing geometric patterns and focused on finding the number of models constituting the pattern. The activities of finding a specific term by finding a rule were evenly presented across the three patterns and the specific term tended to be close to the terms presented in the given task. The activities of representing the rule usually encouraged students to talk about or write down the rule using their own words. Based on the results of these analyses, this study provides specific implications on how to develop subsequent mathematics curricular materials regarding pattern activities to enhance elementary school students' algebraic thinking.

• Journal of Educational Research in Mathematics
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• v.16 no.4
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• pp.367-386
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• 2006

There are two strands for considering tile relationships between education and technology. One is the viewpoint of 'learning from computers' and the other is that of 'learning with computers'. In this paper, we call mathematics education with computers as 'computers and mathematics education' and this computer environments as microworlds. In this paper, we first suggest theoretical backgrounds ai constructionism, mathematization, and computer interaction. These theoretical backgrounds are related to students, school mathematics and computers, relatively As specific strategies to design a microworld, we consider a physical construction, fuctiionization, and internet interaction. Next we survey the different microworlds such as Logo and Dynamic Geometry System(DGS), and reform each microworlds for mathematical level-up of representation. First, we introduce the concept of action letters and its manipulation for representing turtle actions and recursive patterns in turtle microworld. Also we introduce another algebraic representation for representing DGS relation and consider educational moaning in dynamic geometry microworld. We design an integrating microworld between Logo and DGS. First, we design a same command system and we get together in a microworld. Second, these microworlds interact each other and collaborate to construct and manipulate new objects such as tiles and folding nets.