• Journal of applied mathematics & informatics
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• 제12권1_2호
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• pp.299-305
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• 2003

The central limit theorems are obtained for stationary linear processes of the form Xt = (equation omitted), where {$\varepsilon$t} is a strictly stationary sequence of random variables which are either linearly positive quad-rant dependent or associated and {aj} is a sequence of .eat numbers with (equation omitted).

• Journal of applied mathematics & informatics
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• 제38권3_4호
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• pp.201-209
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• 2020

We introduce and study some basic properties of rough I-convergent of triple sequence spaces and also study the set of all rough I-limits of a triple sequence spaces.

• 대한수학교육학회지:수학교육학연구
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• 제21권4호
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• pp.379-398
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• 2011

수학교육에서 증명과 반박은 명제가 왜 참인지 혹은 거짓인지를 판별하게 해주고 거짓으로 판명된 명제를 참인 명제로 정교화하는 과정에서 중요한 요소가 된다. 그렇기에 증명활동과 반례생성 두 가지를 함께 학습하는 것은 수학을 배우는 학생들에게 주어진 명제에 내포되어 있고 함축되어 있는 의미에 대한 깊은 통찰력과 명확한 이해를 제공해 줄 수 있다. 최근 많은 논문을 통해 학생들이 수학적 증명에 어려움을 겪고 있다는 증거가 나타나고 있다. 그러나 해당 연구의 대부분은 예비교사들이 수열의 극한 부분에 대하여 증명과 반례를 생산해 내는 능력에만 초점을 맞추고 있다. 따라서 본 연구에서는 예비교사들을 대상으로 하여 수열의 극한 부분에 대한 수행결과 분석을 통하여 증명활동과 반례생성에 대한 능력정도와 접근 방법 등을 알아보고자 한다. 본 연구의 목적은 예비교사들이 반례와 증명을 생성하는 것에 대한 조사에 공헌하는 것이며 예비교사들의 증명과 반례생성 능력 그리고 수학 개념들에 대한 이해의 정도를 식별하고 확인하는 것이다. 또한, 연구를 통하여 참가자들이 주어진 명제들에 대한 답을 작성하는 것에 어려움을 겪는다는 것을 알게 되었고 이를 바탕으로 증명과 반례를 가르치고 배우는 것에 더욱 노력을 기울여야만 한다는 것을 알 수 있었다. 덧붙여, 이 연구의 분석을 통하여 현행 커리큘럼과 교육 방법에 대하여 통찰력을 제공하게 될 수 있을 것이고 예비교사들의 수학과정 학습을 향상시킬 수 있는 방향을 제시한다는 교육적 시사점을 얻을 수 있을 것이다.

• Journal of the Korean Statistical Society
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• 제24권1호
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• pp.219-224
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• 1995

A central limit theorem with random indices is obtained for stattionary martingale difference sequences.

• 대한수학회보
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• 제51권4호
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• pp.957-964
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• 2014

In this paper, we prove that there is no branch point in the Lorentz space (M, d) which is the limit space of a sequence {($M_{\alpha},d_{\alpha}$)} of compact globally hyperbolic interpolating spacetimes with $C^{\pm}_{\alpha}$-properties and curvature bounded below. Using this, we also obtain that every maximal timelike geodesic in the limit space (M, d) can be expressed as the limit curve of a sequence of maximal timelike geodesics in {($M_{\alpha},d_{\alpha}$)}. Finally, we show that the limit space (M, d) satisfies a timelike triangle comparison property which is analogous to the case of Alexandrov curvature bounds in length spaces.

• 대한수학회보
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• 제40권4호
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• pp.715-722
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• 2003

A functional central limit theorem is obtained for a stationary linear process of the form $X_{t}=\;{\Sigma_{j=0}}^{\infty}a_{j}{\epsilon}_{t-j}, where {${\in}_{t}$｝is a strictly stationary associated sequence of random variables with $E_{{\in}_t}{\;}={\;}0.{\;}E({\in}_t^2){\;}<{\;}{\infty}{\;}and{\;}{a_j}$ is a sequence of real numbers with (equation omitted). A central limit theorem for a stationary linear process generated by stationary associated processes is also discussed.

• 대한수학회논문집
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• 제28권3호
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• pp.571-580
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• 2013

In this paper, we extend the familiar limit curve theorem in [2] to a situation where each causal curve lies in a sequence of compact interpolating spacetimes converging to a limit Lorentz space in the sense of Lorentzian Gromov-Hausdorff distance.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권1호
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• pp.54-60
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• 2006

A power limiting algorithm is proposed for stable operation of grid-connected inverter in case of grid voltage unbalance considering the operation limit of inverter. During the voltage unbalance the control performance of Inverter. is degraded and the output power contains 120Hz ripple due to the negative sequence of voltage. In this paper, conventional dual sequence current controller is implemented to solve these problems using separated control of positive and negative sequence. Especially the maximum power limit which guarantees the maximum rated current of the inverter is automatically calculated as the instant grid voltage changes. As soon as the voltage recovers the proposed algorithm can return to the normal power control mode accomplishing low voltage ride through. Proposed algorithm is verifed using PSCAD/EMTDC simulations and tested experimentally at 4.4kW wind turbine simulator set-up.

• 한국수학교육학회지시리즈A:수학교육
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• 제57권2호
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• pp.157-177
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• 2018

The students in secondary schools have been taught calculus as an important subject in mathematics. The order of chapters-the limit of a sequence followed by limit of a function, and differentiation and integration- is because the limit of a function and the limit of a sequence are required as prerequisites of differentiation and integration. Specifically, the limit of a sequence is used to define definite integral as the limit of the Riemann Sum. However, many researchers identified that students had difficulty in understanding the concept of definite integral defined as the limit of the Riemann Sum. Consequently, they suggested alternative ways to introduce definite integral. Based on these researches, the definition of definite integral in the 2015-Revised Curriculum is not a concept of the limit of the Riemann Sum, which was the definition of definite integral in the previous curriculum, but "F(b)-F(a)" for an indefinite integral F(x) of a function f(x) and real numbers a and b. This change gives rise to differences among ways of introducing definite integral and explaining the relationship between definite integral and area in each textbook. As a result of this study, we have identified that there are a variety of ways of introducing definite integral in each textbook and that ways of explaining the relationship between definite integral and area are affected by ways of introducing definite integral. We expect that this change can reduce the difficulties students face when learning the concept of definite integral.

• Journal of the Korean Statistical Society
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• 제32권1호
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• pp.11-20
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• 2003

Let｛Ｘt｝be an m-dimensional linear process of the form (equation omitted), where｛Zt｝is a sequence of stationary m-dimensional weakly associated random vectors with EZt = O and E∥Zt∥$^2$＜$\infty$. We Prove central limit theorems for multivariate linear processes generated by weakly associated random vectors. Our results also imply a functional central limit theorem.