• East Asian mathematical journal
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• 제26권2호
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• pp.281-299
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• 2010

In this study we develop mathematical tools for measuring the Geumgang Ratio and we call them Geumgang Ratio Calipers. Also we show a teaching method for ratio through experimental mathematics. With Geumgang Ratio Calipers students measure the Geumgang Ratio in their bodies, materials for everyday life and the Sukgulam. Through this activity, students obtained an interest in mathematics and gained a positive attitude for mathematics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권3호
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• pp.1015-1029
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• 2021

Modern technology offers many ways to enhance teaching and learning that in turn promote the development of tools for educational activities both inside and outside the classroom. Many educational programs using the augmented reality (AR) technology are being widely used to provide supplementary learning materials for students. This paper describes the potential and challenges of using GeoGebra AR in mathematical studies, whereby students can view 3D geometric objects for a better understanding of their structure, and verifies the feasibility of its use based on experimental results. The GeoGebra software can be used to draw geometric objects, and 3D geometric objects can be viewed using AR software or AR applications on mobile phones or computer tablets. These could provide some of the required materials for mathematical education at high schools or universities. The use of the GeoGebra application for education in Laos will be particularly discussed in this paper.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제19권1호
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• pp.81-88
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• 2015

This study used a posttest control group design and to find out differences between students' self-regulated learning strategies in traditional and non-traditional classroom. To this end, 131 first year university students within the experimental and control groups took part in the study. While ICT-based approach was used as the main medium of instruction in the experimental group, in the control group the paper-based traditional method was used. A survey adapted from Davaanyam [Davaanyam, T. (2013). The structural relationships among Mongolian students' attitudes toward mathematics, motivational beliefs, self-regulated learning strategies, and mathematics achievement. Ph. D. Dissertation. Jeonju, Jeonbuk, Korea: Chonbuk National Unversity.] was used to gather the data. The results of the study indicated a significant difference between the control and experimental groups in regard with their self-regulated learning. That is to say, the experimental group taught through ICT tools acquired higher levels of self-regulation as compared with the control group instructed through the traditional teaching method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1904-1909
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• 1991

Software linear and exponential acceleration/deceleration algorithms for control of machine axes of motion in industrial robots and CNC machine tools are proposed. Typical hardware systems used to accelerate and decelerate axes of motion are mathematically analyzed. Discrete-time state equations are derived from the mathematical analyses for the development of software acceleration/deceleration algorithms. Synchronous control method of multiple axes of motion in industrial robots and CNC machine tools is shown to be easily obtained on the basis of the proposed acceleration/deceleration algorithms. The path error analyses are carried out for the case where the software linear and exponential acceleration/deceleration algorithms are applied to a circular interpolator. A motion control system based on a floating point digital signal processor (DSP) TMS 320C30 is developed in order to implement the proposed algorithms. Experimental results demonstrate that the developed algorithms and the motion control system are available for control of multiple axes and nonlinear motion composed of a combination of lines and circles which industrial robots and CNC machine tools require.

• 한국정밀공학회지
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• 제32권4호
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• pp.345-351
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• 2015

Machine tools usually consume more energy in cooling systems than in spindle motors. This is largely because circulation pumps in the cooling systems are continuously powered to measure the temperature of spindle motors. In this paper, energy saving algorithms are proposed, which modify this behavior of the circulation pumps in such a way that the circulation pumps run only when it is likely that the information on the temperature is critical to bang-bang control of compressors in cooling systems. A mathematical model is established that explains heat transfer phenomena near the spindle motors. The power consumptions are measured for individual components in a machine tool, and the parameters that appear in the mathematical model are estimated. Computer simulations are performed with the estimated parameters, and the results are compared with the experimental ones. It turns out that a large amount of energy can be saved by using the proposed method.

• 대한의용생체공학회:의공학회지
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• 제30권4호
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• pp.279-287
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• 2009

Magnetic resonance electrical impedance tomography (MREIT) is a new medical imaging modality providing cross-sectional images of a conductivity distribution inside an electrically conducting object. MREIT has rapidly progressed in its theory, algorithm and experimental technique and now reached the stage of in vivo animal and human experiments. Conductivity image reconstructions in MREIT require various steps of carefully implemented numerical computations. To facilitate MREIT research, there is a pressing need for an MREIT software package with an efficient user interface. In this paper, we present an example of such a software, called CoReHA which stands for conductivity reconstructor using harmonic algorithms. It offers various computational tools including preprocessing of MREIT data, identification of boundary geometry, electrode modeling, meshing and implementation of the finite element method. Conductivity image reconstruction methods based on the harmonic $B_z$ algorithm are used to produce cross-sectional conductivity images. After summarizing basics of MREIT theory and experimental method, we describe technical details of each data processing task for conductivity image reconstructions. We pay attention to pitfalls and cautions in their numerical implementations. The presented software will be useful to researchers in the field of MREIT for simulation as well as experimental studies.

• Journal of Advanced Marine Engineering and Technology
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• 제33권7호
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• pp.1003-1011
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• 2009

This study aims at precise control of oil outlet temperature in the oil cooler system of machine tools for enhancement of working speed and processing accuracy. PID control logic is adopted to obtain desired oil outlet temperature of the oil cooler system with hot-gas bypass method. We showed that the gains of PID controller could be easily determined by using gain tuning methods to get the gain of PID controller without any mathematical model. We also investigated various gain tuning methods to design the gains of PID and compared each control performance for selecting the optimal tuning method on the hot gas bypass method through experiments. Moreover, we confirmed excellent control performance with proposed PI controller gain even though disturbances were abruptly added to the experimental system.

• 한국초등수학교육학회지
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• 제11권2호
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• pp.99-115
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• 2007

본 연구의 목적은 현실적 맥락을 활용한 수학화 학습을 실제 현장에 적용하여 이러한 학습이 아동의 수학적 사고에 어떠한 효과를 나타내는지 알아보는 데에 있다. 이러한 연구 목적을 위해 서울시 D초등학교 5학년 2개 학급을 연구 대상으로 6주간 17차시에 걸쳐 실험이 이루어졌고, 실험 설계는 전후 검사 통제집단 설계를 하였다. 또한 1학기말 수학 학업 성취도 평가 결과를 기준으로 선정된 실험 집단의 상(30%), 하(30%) 집단 학생들을 대상으로 하여 시기별(전기-중기-후기)로 관찰, 질문지, 녹음, 활동지와 형성평가지 분석의 방법을 사용하여 현실적 맥락을 활용한 수학화 학습을 통해 나타난 아동의 수학화 과정이 어떠한지를 각 과정별로 분석하여 살펴보았다. 그 결과 현실적 맥락을 활용한 수학화 학습을 실시한 실험집단의 경우 수학의 방법 및 내용적 측면에서 나타난 수학적 사고에서 평균 점수가 비교 집단보다 향상되었고 통계적으로도 유의미한 차이가 나타났다. 또한 현실적 맥락을 활용한 수학화 학습을 실시한 수학 집단에서 수학화 과정의 4단계인 직관적 탐구, 수평적 수학화, 수직적 수학화, 응용적 수학화 각각의 과정에서 상 하위 집단별 학생들은 수업이 전기-중기-후기로 진행되어 갈수록 각 과정의 수학화가 더욱 활발히 일어났음을 알 수 있었다.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제24권3호
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• pp.611-626
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• 2010

본 연구는 일차항수의 합성 성질에 관한 수학적 지식의 발견을 CAS 그래핑 계산기를 도구로 활용하여 조명하였다. 이를 위하여 먼저 CAS 그래핑 계산기와 같은 공학이 도구로 생성되는 의미와 과정을 살펴보았고, 실험수학의 견지에서 CAS를 활용한 관찰, 추측, 추론과 증명 등의 개념 기반형 수학적 활동에 기초한 수학적 지식 발견의 탐구 활동을 구상하였으며, 이 활동의 실제적 적용으로 일차함수의 반복 합성에 의해 얻어진 함수족들의 성질을 분석하였다. 이를 통하여 CAS 그래핑 계산기가 가지는 도구의 기능적 능력인 그래프 그리기, 표의 생성이나 기호 조작은 지필로는 힘든 반복 합성한 함수족의 탐구를 유의미하도록 함을 알 수 있었고, CAS가 수학적 활동에 매개되어 학교수학의 새로운 교수-학습 변화에 대한 주요한 역할을 담당할 수 있음을 확인할 수 있었다.

• 한국소음진동공학회논문집
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• 제13권8호
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• pp.651-657
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• 2003

A new mechanical-electrical hybrid passive damping treatment is proposed to improve the performance of structural vibration control. The proposed hybrid passive damping system consists of a constrained layer damping treatment and a shunt circuit. In a passive mechanical constrained layer damping, a viscoelastic material damping layer is used to control the structural vibration modes in high frequency range. The passive electrical damping is designed for targeting the nitration amplitude in the low frequency range. The governing equations of motion are derived through the Hamilton's principle. The obtained mathematical model Is validated experimentally. The presented theoretical and experimental techniques provide invaluable tools for controlling the multiple modes of a vibrating structure over a wide frequency band.