• Communications of the Korean Mathematical Society
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• v.15 no.3
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• pp.435-451
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• 2000

섀논의 샘플링 정리는 여러 방향으로 확장 발전되어왔으나 본 논문에서는 초함수 이론으로 다룰 수 있는 방향, 즉 좀 더 큰 공간에 속하는 함수에 대한 샘플링 정리를 얻는 것이다. 먼저 샘플링이론의 기본정리인 섀논-코텔니코프 공식을 소개하고 그 자연스런 확장인 페일리-위너 공간, 번스타인 공간에서의 샘플링정리 등을 다루었고 번스타인 공간의 자연스런 확장인 유계인 받침을 갖는 초함수의 푸리에변환 즉, 실공간 위에서 다항식정도로 증가하는 전해석함수에 대한 샘플링 정리를 소개한다. 끝으로 우리의 최근 결과인 실공간 위에서 지수적으로 증가하는 전해석 함수에 대한 샘플링 정리와 그 응용, 그리고 오차추정 등을 다룬다.

• Journal of the Korean School Mathematics Society
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• v.10 no.1
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• pp.91-111
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• 2007

This study investigated how high school students predict the rule, the sum of sequence for the concept of sequence, for the given patterns based on inductive approach using computers that provide dynamic functions and materials that are visual. Students for themselves were able to induce the formula without using the given formula in the textbook. Furthermore, this study examined how these technology and materials affect students' understanding of the concept of actual infinity for those who have the concept of the potential infinity which is the misconception of infinity in a infinity series. This study shows that students made a progress from the concept of potential infinity to that of actual infinity with technology and materials used I this study. Students also became interested in the use of computer and the visualized materials, further there was a change in their attitude toward mathematics.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.1
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• pp.8-18
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• 2002

In this paper, wave energy absorption of OWC(oscillating water column) device is analyzed. The analytic model consists of a partially immersed circular vertical cylinder open at its end and an air turbine connected with the air chamber. The boundary value problem is decomposed into scattering problem related to scattering by an incident wave in the absence of a pressure variation and radiation problem describing the flow due to an oscillating pressure in the absence of an incident wave. By invoking the continuity of an air flow inside the chamber, the oscillating pressure in a chamber is derived. With oscillating pressure, the mean power absorbed by OWC device and the capture width are obtained. In numerical calculation, the induced volume flux across the internal free surface of the chamber in the scattering and radiation problem and the maximum capture width are compared with various design parameters such as radius and submergence depth of chamber and wave conditions. The maximum capture width obtained by choosing the optimal value of turbine constant occurs at the first resonant mode (Helmholtz mode) among the natural frequencies of a circular cylinder chamber.

• Journal for History of Mathematics
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• v.27 no.2
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• pp.139-152
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• 2014

This paper aims to compare and contrast Kierkegaard and Turing, whose birth dates were one hundred years apart, analyzing them from the perspective of the limit. The model of analysis is two concentric circles and movement in them and on the boundary of outer circle. In the model, Kierkegaard's existential stages have 1:1 correspondences: aesthetic stage, ethical stage, religious stage A and religious stage B correspond to inside of the inner circle, outside of the inner circle, the boundary of the outer circle and the outside of the outer circle, respectively. This paper claims that Turing belongs to inside of the outer circle and moves to the center while Kierkegaard belongs to outside of the outer circle and moves to the infinity. Both of them have movement of potential infinity but their directions are opposite.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.3-3
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• 2021

하천의 식생은 생태서식처 제공, 강턱이나 하안 경사의 안정, 영양염류나 오염물 차단에 의한 수질 개선 등의 다양한 생태서비스를 제공하는 반면, 과도하고 편중된 식생 분포로 인해 흐름저항이 증가하고 이로 인한 홍수위 상승과 홍수피해 위험이 가중될 수 있다. 기후변화 영향과 토지이용 변화에 따른 수리수문 특성 변화와 유역으로부터 영양염류의 유입은 하천내 식생이 과도하게 퍼지는 직접적인 원인이 될 수 있다. 과도한 식생분포로 인한 흐름저항과 홍수위 상승을 평가하기 위해 식생하도의 흐름저항과 관련된 매개변수의 다양성과 복잡성에 따른 해석상의 한계에도 불구하고 이에 대한 이론적 해석과 수학모형의 개발, 실험실 수로와 하천현장조사, 수치모형을 이용한 예측 등의 다양한 연구가 수행되고 있다. 본 연구에서는 소규모 실험실 수로에서 단순화된 식생 구조와 배열이 적용되는 한계성과 상류에서 유입되는 유량과 유속 등의 수리조건을 통제할 수 없는 현장실험의 한계성을 보완하고자 목본류 형태의 식생패치를 실규모 하천실험 수로에 조성하여 통제된 수리조건에서의 식생하도의 구간 흐름저항을 추정하기 위한 계측 실험을 수행하였다. 실규모 실험에서는 피에조미터 형식의 정밀 압력식 센서를 이용하여 수위와 수면경사를 계측하였으며, 실험구간의 접근 수로에서 ADCP(Acoustic Doppler Current Profiler)를 이용하여 유입 유량에 대한 정보를 수집하였다. 전체 수로 길이 약 600 m, 하폭 11 m, 깊이 2 m 규모의 실규모 하도 일부 80 m 완경사 구간에 식생패치를 설치하고 구간 수면경사를 실측함으로써 식생하도의 흐름저항을 직접 산정하였다. 이러한 실규모 식생하도의 실험을 통해 식생패치의 밀도, 횡적 차단면적, 구간 차단부피, 목본 식생의 물리적 특성, 식생패치의 배열 등의 다양한 식생분포 조건에 따른 수리조건별 흐름저항 값의 변화를 분석할 수 있다. 식생하도에 대한 정확한 흐름저항 추정과 홍수위 변화에 대한 해석은 하천 식생의 생태서비스와 홍수방어의 하천 치수효과의 최적 솔루션을 제시하기 위한 하도관리의 다양한 방안을 제시하는데 필수적인 정보로 활용될 수 있다.

• Communications of Mathematical Education
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• v.33 no.2
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• pp.47-66
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• 2019

The purpose of this study is followings. First, we develop and apply teaching and learning methods for conducting team projects in flipped calculus class. Second we collect data such as team reports, individual reviews, and surveys during class activities. Third we survey the impacts on participation in student team activities, advanced studying, communication and collaboration. A total of 120 engineering and science majoring students participated in the 16-week long class study administered in team project learning styles in Spring 2018. There were two characteristics of this class. First students studied concepts and examples with video in pre-class and did the team project learning in the classroom. Second we used Google Drive to record team project progress, and to make sure the instructor to intervene appropriately in team activities. We conducted a team project inside and outside the classroom. This could lead the instructor to advise students and so their participation in team activity increased. As a result, it not only had a good effect on communication and cooperation, but also had an effect on advanced learning.

• Journal of the Korean Wood Science and Technology
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• v.18 no.4
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• pp.3-8
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• 1990

근년에 전세계에서 목재건조 기술의 주요 관심사는 첫째 건조응력발생과 건조결함 예방이고, 다음은 건조실 제어시스템, 건조스케줄개발, 목재수분이동, 함수율측정, 새로운 건조방법개발, 건조에너지 절약, 경제성분석, 태양열건조, 수학적모델링, 건조전처리, 마이크로웨이브 건조, 건조실 구성과 정비, 건조종기결정, 감압건조, 공정제어와 콘다숀닝, 제습건조, 목재치수 안정 및 고온건조 등의 순위이다. 건조중 발생하는 결함들은 건조경비 증가에 절대적인 영향을 끼칠 수 있다. 예를 들면, 가구공장에 있어서 건조재의 품등 향상에 따른 1%의 수율 증대 효과는 가구 부품 1000 보오드피트당 23$의 생산비를 절감할 수 있고, 활엽수재의 천연건조시 수반되는 건조손상은 생재의 23%를 초과할 수 있다. 본 총설이 각종 문제를 개선하고 건조경비를 절감하는데 기여할 수 있기를 바라며, 또한 단판, 칩 또는 땔감과 같은 비제재품에 관한 건조에 관한것은 제외하였다.

• Journal of Gifted/Talented Education
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• v.15 no.1
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• pp.85-102
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• 2005

Some properties on the mathematical hyper-dimensional figures by 'the principle of the permanence of equivalent forms' was investigated. It was supposed that there are 2 conjectures on the making n-dimensional figures : simplex (a pyramid type) and a hypercube(prism type). The figures which were made by the 2 conjectures all satisfied the sufficient condition to show the general Euler's Theorem(the Euler's Characteristics). Especially, the patterns on the numbers of the components of the simplex and hypercube are fitted to Binomial Theorem and Pascal's Triangle. It was also found that the prism type is a good shape to expand the Hasse's Diagram. 5 mathematically gifted high school students were mentored on the investigation of the hyper-dimensional figure by 'the principle of the permanence of equivalent forms'. Research products and ideas students have produced are shown and the 'guided re-invention method' used for mentoring are explained.

• Communications of Mathematical Education
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• v.36 no.1
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• pp.171-199
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• 2022

In this study, we review contents to supplement the descriptions of the history of mathematics in the 2015 mathematics textbooks and teacher guides for the elementary school level and offer our opinion on them. For this purpose, we conducted a literature review on 24 types of 2015 mathematics textbooks and teacher guides for the elementary school level. The results of this study are as follows: A total of 10 topics were found whose contents were supplemented with descriptions. They were the "Arithmetic of the Ancient Egyptians," the "A'h-mosè Papyrus in Mathematics Textbooks of the Ancient Egyptians," "The Old Akkadian Square Band in Mesopotamia," "The Relationship of the Old Babylonians in Mesopotamia with the Angle," "The Pi of the Ancient Egyptians and the Old Babylonians," "The Square Roots 2 of the Ancient Egyptians and the Old Babylonians," "The Relationship of the Islamites with the Decimal Fraction," "Two Arguments for the Roots of the Golden Ratio," "The Relationship of Archimedes with the Exhaustion Method," and "The Design of Flats." Then, their specific supplements were suggested. It is expected that this will overcome the perspective of the history of the Axial Age and acknowledge and accept the perspective evidencing the transfer of mathematical culture from Ancient Egypt and Old Babylonia to Ancient Greece and Hellenism, and then through Central Asia to Europe.

• Journal of the Korean School Mathematics Society
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• v.22 no.4
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• pp.395-413
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• 2019

The purpose of this study was to find out how Blended e-Learning affected the teaching and learning of engineering mathematics for engineering students. It has researched the application condition of Blended e-Learning and the students' attitude in the offline classes of students. The subject were 42 students of Junior in the Department of Mechanic Engineering in M-University participated in the study. The lecturer taught the class for the students by fact-to-face teaching at the offline. It was recorded all processes during the class, and the video was loaded at the Learning Management System(LMS). The students studied online by themselves. This study investigated the attitude of students at the offline and the Utilization of Online Data by learners through the mixed class for one semester. The results were as follows. First, Blended e-Learning applied engineering mathematics affected positively for the self-regulated and individualized learning to the students. Second, Blended e-Learning has shown a positive impact on the teaching and learning of engineering mathematics. Finally, it also had a positive effect on the class satisfaction level of students.