• Journal of Ocean Engineering and Technology
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• v.5 no.2
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• pp.43-50
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• 1991

본 연구에서는 극한 파고를 추정하는 방법을 제시하였다. Type III분포에 근거해서 4가지의 방법들에 의해 분포 함수의 파라미터들을 추정하였다. 실제 자료와 추정된 분포 함수 값의 차이를 다항식을 도입하여 함으로써 그 오차를 줄였다. 이 방법들의 타당성을 보이기 위해 실제 해상의 자료들을 이용하여 분포 함수를 구하고 조우 주기들에 해당하는 극한 파고를 계산하여 보았다.

• Journal of the Korean School Mathematics Society
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• v.17 no.4
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• pp.697-716
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• 2014

The purpose of this paper is to investigate high school students' learning characteristics which revealed in their learning process of limit using GeoGebra. And we are going to analyze effects of teaching of limit using GeoGebra to high school students' interesting and attitudes for mathematics learning. To do this, we selected three high school students as participants and ask them performing limit learning using GeoGebra. We recorded their problem solving process. Through analyzing their problem solving process relate to their solution, we found the followings: First, students did not logically approach based on mathematical properties or given materials, rather showing tendency decide with self-conscious and intuition. Second, it is possible that former reasoning strategies disturb following reasoning in the process of high school students' mathematics learning. Third, learning process of limit using GeoGebra help high school students to identify and correct their errors relate to limit learning. Forth, learning process of limit using GeoGebra positively effects to high school students' interesting and attitudes for mathematics learning.

• Communications of Mathematical Education
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• v.18 no.1 s.18
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• pp.289-296
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• 2004

수업시간을 이용하지 않고 인터넷을 이용하여 조사와 학생 스스로 학습할 기회와 자료를 제공하여 개념을 이해할 모델을 만들어 본다. 함수의 합성과 극한에 대한 이해도를 1차로 조사한 결과는 정답율이 7.5%에 불과하여 같은 설문지에 대해 각자 공부하고 대답하도록 2차 조사를 하고, 함수의 합성과 합성함수의 극한에 대해 개념의 이해를 도우려고 그래프를 이용한 자료를 수집하여 확실하고 쉽게 이해할 기회를 제공하며 새로운 교수-학습 방법을 개발한다.

• Communications of Mathematical Education
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• v.25 no.1
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• pp.63-78
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• 2011

The purpose of this study is to explore a teaching method of limits of functions with more intuitive and visual of CAS graphing calculators rather than with the rigorous ${\epsilon}-{\delta}$ method. Texas Instruments Voyage200 CAS graphing calculators are used for studying the possibility of the use of technology in calculus course. For this, various related theoretical constructs are reviewed: concept image, concept definition, cognitive conflict, the use of visualization of technology for calculus concepts, the theory of APOS, and local straightness. Based on such theoretical constructs this study suggests a teaching method of limits of functions with embodied visualization of CAS graphing calculators.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.207-207
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• 2023

데이터 기반 강수 예측 모델은 극한 강수 이벤트의 크기를 과소 추정하는 경향이 있다. 이는 훈련 데이터에 극한 강수 이벤트보다 일반적인 강수 이벤트가 많이 포함되어 있기 때문이다. 본 연구는 이러한 딥러닝의 데이터 불균형 문제를 해소하고자 모델을 학습시킬 때 격자별 극한 강수에 더 큰 가중치를 주어 극한 강수 예측의 정확성을 높이는 방법을 제안한다. 딥러닝 모델 중 공간-시간 필드를 정확하게 예측할 수 있는 ConvLSTM 기반 강수 예측 모델을 활용하여 레이더 강수량을 예측하였다. 먼저, 훈련 기간 동안의 강수 이벤트의 누적 분포 함수 CDF(Cummulative distribution funcion)을 그린 후 극한 강수 이벤트와 일반적인 강수 이벤트의 분포를 확인하였다. 그다음, 적은 분포를 가진 극한 강수 이벤트의 더 큰 가중치를 두어 모델을 학습시켰다. 이 모델은 대한민국 중부 지역 (200km x 200km)의 5km-10분 해상도 레이더-계량기 복합 강수 필드에 대해 2009-2014년 기간 동안 훈련 되었고 2015-2016년 동안 모델의 훈련을 검증 하였고, 2017-2018년 동안 테스트 되었다. 다양한 가중치 함수를 기반으로 훈련 시킨 결과 최적화 가중치 함수 모델의 평균 NSE는 0.6 평균 RMSE는 0.00015 그리고 극한 강수 이벤트만 따로 추출한 평균 MAE는 6이다. 결과적으로 제안된 모델은 기존 방법에 비해 예측 성능을 향상 시켰으며, 격자별 가중치를 두었을 경우 일반적인 강수 이벤트 뿐만 아니라 극한 강수 이벤트의 예측의 정확도를 향상시켰다.

• Journal of the Korean School Mathematics Society
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• v.23 no.4
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• pp.523-556
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• 2020

In this paper, we investigated and analyzed how freshmen in science and engineering colleges understand the limit and the continuous concept of function. The survey found that there were more college students who did not do so than those who understood each concept by linking the concepts together. Therefore, in order to teach college general mathematics, It is necessary to analyze how college students are connecting mathematical concepts. And it is necessary to apply teaching-learning methods suitable for individuals.

• Journal of the Korean School Mathematics Society
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• v.26 no.2
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• pp.87-110
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• 2023

This study aimed to proposed repeated reading aloud, which combines repetitive reading and reading aloud, as a method for teaching and learning mathematics. We investigated the effect of repeated reading aloud on students' academic achievement and cognitive load, and explored the implications of repeated reading aloud as a method for teaching and learning mathematics. To this end, we conducted a case study involving repeated reading aloud for two units: the limit of a function and the number of cases. The study targeted four 9th-grade students and four 10th-grade students, analyzing how their academic achievement and cognitive load changed. As a result, the eight students showed positive changes in academic achievement and cognitive load as the repeated reading aloud accumulated. When comparing the units, the academic achievement was lower for the limit of function than the number of cases. In terms of cognitive load, students exhibited higher cognitive load in the unit on the limit of function. When compared cognitive load by grade, there was no significant difference after 3rd repeated reading. However, in both units, the academic achievement of four 10th-grade students was higher than that of four 9th-grade students. Nonetheless, the gap narrowed as the reading aloud was repeated.

• Journal of IKEEE
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• v.6 no.2 s.11
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• pp.128-135
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• 2002

We use the saturation nonlinear feedback element to generate self-oscillation in order to find an ultimate gain and period of linear plant. The use of saturation nonlinear feedback element can improve accuracy of an ultimate gain and period of unknown linear plant. An ultimate gain and period of linear plant can be used to tune a PID controller parameters. It is possible that an asymmetric oscillation can be occurred under the special circumstances such as with static load disturbance. We analyze an asymmetric self-oscillation. As the results of an analysis, we propose a method to find an ultimate gain and period of linear Plant under the asymmetric self-oscillation.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.2
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• pp.1-7
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• 1992

The computational methods of extreme sea level are developed in this study. Based on type III asymptotic distribution, non-linear multiple regression method, skewness method and maximum likelihood method are used to evaluate the parameters of the distribution. The difference between real data and evaluated distribution function is fitted to get more desirable accuracy by employing polynominals. The numerical examples are given in the last section in order to illustrate the application of the present scheme.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.263-269
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• 1998

We use the slope bounded saturation nonlinear feedback element instead of relay to find ultimate gain and period of linear plant. Saturation nonlinear element reduces the high harmonics of plant output. The reduction of high harmonics improve the accuracy of describing function method used to find ultimate gain and period. We give a simple procedure to find ultimate gain and period with saturation nonlinear element. A PID controller design method with known time delay element is also given, which is very useful when oscillation is not occurred with nonlinear element.