• Journal of Elementary Mathematics Education in Korea
• /
• v.7 no.1
• /
• pp.45-64
• /
• 2003

This study analyzes divisor and multiple in elementary school mathematics textbooks published according to the first to the 7th curriculum, in a view point of the didactic transposition theory. In the first and second textbooks, the divisor and the multiple are taught in the chapter whose subject is on the calculations of the fractions. In the third and fourth textbooks, divisor and multiple became an independent chapter but instructed with the concept of set theory. In the fifth, the sixth, and the seventh textbooks, not only divisor multiple was educated as an independent chapter but also began to be instructed without any conjunction with set theory or a fractions. Especially, in the seventh textbook, the understanding through activities of students itself are strongly emphasized. The analysis on the each curriculum periods shows that the divisor and the multiple and the reduction of a fractions to the lowest terms and to a common denominator are treated at the same period. Learning activity elements are increase steadily as the textbooks and the mathematical systems are revised. The following conclusion can be deduced based on the textbook analysis and discussion for each curriculum periods. First, loaming instruction method also developed systematically with time. Second, teaching method of the divisor and multiple has been sophisticated during the 1st to 7th curriculum textbooks. And the variation of the teaching sequences of the divisor and multiple is identified. Third, we must present concrete models in real life and construct textbooks for students to abstract the concepts by themselves. Fourth, it is necessary to develop some didactics for students' contextualization and personalization of the greatest common divisor and least common multiple. Fifth, the 7th curriculum textbooks emphasize inquiries in real life which teaming activities by the student himself or herself.

• Journal of Educational Research in Mathematics
• /
• v.27 no.4
• /
• pp.833-855
• /
• 2017

This study aims to reinvestigate the reason for introducing radian as a new unit to express the size of angles, what is the meaning of radian measures to use arc lengths as angle measures, and why is the domain of trigonometric functions expanded to real numbers for expressing general angles. For this purpose, it was conducted historical, mathematical and applied mathematical analyzes in order to research at multidisciplinary analysis of the radian concept. As a result, the following were revealed. First, radian measure is intrinsic essence in angle measure. The radian is itself, and theoretical absolute unit. The radian makes trigonometric functions as real functions. Second, radians should be aware of invariance through covariance of ratios and proportions in concentric circles. The orthogonality between cosine and sine gives a crucial inevitability to the radian. It should be aware that radian is the simplest standards for measuring the length of arcs by the length of radius. It can find the connection with sexadecimal method using the division strategy. Third, I revealed the necessity by distinction between angle and angle measure. It needs justification for omission of radians and multiplication relationship strategy between arc and radius. The didactical suggestions derived by these can reveal the usefulness and value of the radian concept and can contribute to the substantive teaching of radian measure.

• The Journal of Korean Association of Computer Education
• /
• v.5 no.4
• /
• pp.111-121
• /
• 2002

With advancement of computer and network, world wide web(WWW) as medium of information communication is generalized in many fields. In educational aspect, applications of WWW as alternative media for class teaching or printed matter are increasing. In this article, we demonstrate a web based electronic text on the 'probability and statistics' which is one of six fields of mathematics in 7th curriculum. This text places importance on comprehension of concepts and fundamentals of probability and statistics as applied sciences and not on simple calculations of probability and statistics.

• Defense and Technology
• /
• no.11 s.165
• /
• pp.26-33
• /
• 1992

국과연이 산.학.연에 지원하고 있는 기초연구사업의 2차년도 연구결과 발표회가 국과연 산학회관에서 10월27일부터 11월 4일까지 열렸습니다. 이번 발표회는 물리.광학.전기.전자, 화.공학, 수학.전산, 기계.항공, 해양.조선, 재료공학 등 7개 분과로 나뉘어 진행되었습니다. 국과연은 지난 91년 12월에 제1회 발표회를 가진바 있으며, 이번 네2회 발표회는 지난회의 48개 과제에 대한 중간 실적 평가와 함께 새로 선정된 29개 과제의 연구 결과 발표장이 되었습니다. 이에 이번호에는 사업평가에 관한 연구(총괄 p.p 26-33)와 함께 6개 부문별로 각각의 발표내용을 발췌하여 게재(p.p 34-45)합니다

• The Science & Technology
• /
• v.35 no.9 s.400
• /
• pp.43-72
• /
• 2002

[수학] 7대 수수께끼 주제당 1백만달러 상금 걸어 리만가설 풀면 통신비밀 완벽 유지 길 터/[물리] 물질 기본 웨이클ㆍ허공의 요동설 신비 우주 팽창 가속ㆍ진공에너지 설도 미궁/[화학] 화학반응 경로와 반응속도 해석 큰 난제 분자집단 평형깨졌을 때 해석도 문제/[생물] 의식ㆍ사고ㆍ상상력ㆍ언어 등 정신능력 신비 신경전달물질 분비 메커니즘 규명 못해/[지구과학] 판구조론ㆍ하와이 화산활동 설명 안돼/[천문우주과학] 새 사실 밝혀질수록 또다른 궁금증 제기/[기상] 지구는 더워지고 있는가 추워지고 있는가 엘니뇨ㆍ오존층 등 기후변화 현상만 겨우 파악/[농학] 진화론 자리매김했지만 의문점 남아

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.711-711
• /
• 2012

이 연구에서는 수심적분된 이차원 비정상 수치모형인 KU-RLMS 모형의 잠김/드러남 기법을 개선하고, 기존의 WAD 기법과 새로 도입한 기법의 정확도 평가를 수행하였다. 기존의 WAD 기법은 수학적으로는 다소 불완전하지만 수치적으로는 손쉬운 방법으로써, 각 시간 단계에서 잠긴 격자 또는 드러난 격자를 시험하고, 각 격자의 경계에서 플럭스에 대한 개폐 조건을 적용하는 방법을 사용하였다. 개선된 기법은 WAD 경계에서의 질량보존을 고려하는 방법이다. 두 가지 잠김/드러남 처리 과정의 정확도 비교는 포물형 수조에 대한 해석해와 수치모형의 결과를 비교하는 방법을 사용하였다. 기존에 WAD 기법은 수치해와 해석해의 위상차가 발생하는 것을 확인할 수 있으며, 진폭은 조금씩 감소하는 현상이 나타났지만, 개선된 기법을 사용할 경우 위상차와 진폭감소 현상이 현저히 개선됨을 확인할 수 있었다.

• Parasites, Hosts and Diseases
• /
• v.24 no.1
• /
• pp.3-141
• /
• 1986

간흡충은 우리나라를 비롯하여 중국, 대만, 일본 및 월남등지에 널리 분포되어 있으며 1947년에 Stoll씨의 통계에 의하면 세계적으로 1,900만명이 넘는 감염자가 있다고 하였다. 현재 우리나라에서만 약 200만명의 간흡충 감염자가 있을 것으로 추산되고 있다. 간흡충은 McConnell이 1874년에 인도의 Calcutta에서 한 중국인의 간담도에서 본충을 처음 발견한 것이다. 이것을 Cobbold(1875)가 Distoma sinense라고 명명하였다가 후에 Looss (1907)가 Clonorchis sinensis라고 하였다. Kobayashi (1910)는 담수어가 간흡충감염의 중간숙주로 작용한다는 것을 처음으로 발견하였고 Muto (1918)에 의하여 왜우렁이가 제1중간숙주임을 발견함으로서 간흉충의 생활사가 확실해 졌다. Faust 및 Khaw (1927)에 의하여 중국에서 간흡충의 생물학 및 역학에 관한 광범한 연구업적이 발표된 이래 일본, 한국, 중국등 여러곳에서 많은 사람들에 의하여 연구되어 왔다. 그러나 적절한 치료방법이 없었고 또 민물고기를 생식하는 식습관과 위생시설의 미비등 여러가지 요인때문에 예방이 어려움에 직면하였다. 최근 다행히 새로이 개 발된 praziquantel이 간흡충중에 대하여 우수한 치료효과를 나타내고 집단치료에도 적합하다는 것이 증명됨으로서 간흡충증 예방과 관리에 큰 서광이 보이게 되었다. 따라서 간흉충증의 발생과 임상적 병증의 중요성을 좀 더 이해하기 위하여 간흡충체의 미세구조, 병인, 역학, 임상증상등 최근 알려진 새로운 지견과 우리나라에 있어서 간흡충증의 분포 및 유행지 형성 상황을 수학적으로 역학적 분석을 시도하였다. 그리고 과거 간흡충중의 화학치료에 관한 연구성적을 종합하여 화학요법제의 특성 빚 치료 적용여부에 대하여 논하였고 각약제의 시험관내 및 실험동물에 있어서의 살충효과와 임상시험에 있어서의 치료효과 및 부작용에 대하여 기술하였다. 그리고 새로 개발된 praziquantel의 간흡충에 대한 작용기전에 대하여도 논하였다. (중략)

• Nuclear Engineering and Technology
• /
• v.23 no.1
• /
• pp.30-40
• /
• 1991

For automatic power control of KMRR, a new method, Reactivity Constraint Method, is applied for time optimal control. This method limits the net reactivity to the amount that can be offset by instantaneous control rod action. The reactivity to be constrained for the constant reactor period should be obtained by the dynamic period equation. A new formulation of the dynamic period equation for 2-point kinetics model is presented. A methematical controller model was applied to the plant simulator, KMRSIM to test this control law. The performance test showed that reactivity constraint approach is also a reliable means for reactor power change control.

• Progress in Medical Physics
• /
• v.17 no.1
• /
• pp.6-16
• /
• 2006

The goal of this study was to develop new indices for effectively evaluating the dose coverage and homogeneity based on the target-volume dose-volume histogram (TV-DVH) of intensity-modulated radio-therapy treatment plans. A new coverage Index and a new homogeneity index were developed by integrating a modified TV-DVH and by fitting a TV-DVH with a modified step function, respectively. The coverage index, named the l-index, indicates whether the dose coverage for the target volume is adequate based on user-defined criteria. A lower l-index indicates higher dose coverage of the tumor volume. The index for assessing dose homogeneity in a target volume, named the n-index, is more accurate than the conventional method in evaluating the dose homogeneity in a tumor volume. The baseline treatment plan for a target volume coverage and homogeneity is discussed. The proposed simple indices have been demonstrated to be effective in evaluating the dose coverage and homogeneity for TV-DVHs.

• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 2001.05a
• /
• pp.237-246
• /
• 2001

In this paper we introduce a solution to improve the unfairness problem and to remove the waste of bandwidth in the distributed queue dual bus system. This solution requires only a minor modification of the current protocol and further shows no bandwidth wastes when we try to resolve the unfairness problem occurred in current DQDB protocol. There has been many problem in DQDB system in terms of fairness of sending message in each node. In order to solve this problem, Bandwidth Balancing technic and proportional assignment technic have been introduced. It is, however, to note that the waste of bandwidth problem is still existing in those technics, even though there has been significant improvement as to the fairness problem. In this paper we introduce a new solution to remove the waste of bandwidth problem while we are still obtaining the improved fairness of the network. By following this new solution, the simulation result shows higher throughput and lower message delay than previously proposed technics.