• Journal of the Korean School Mathematics Society
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• v.20 no.4
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• pp.537-560
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• 2017

This study aims to investigate secondary mathematics teachers' beliefs about graphing calculator use in mathematics classrooms. For the purpose, we adopted a research instrument that was developed by Brown et. al(2007) and surveyed 32 mathematics teachers about their beliefs about graphing calculator use and teaching practice with calculators in their mathematics instruction. The data analysis suggested that the teachers rarely used calculators in their instruction and they have not had opportunities to use calculators in learning and teaching mathematics. Also, results suggested that the many teachers showed "Crutch beliefs"about the use of calculators in mathematics instruction.

• Journal of the Korean School Mathematics Society
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• v.17 no.1
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• pp.45-71
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• 2014

In learning the conic session, there is a gap between the curricula of the high school and the university level for the pre-service math teachers. So through the art of problem posing, 38 number of pre-service teachers worked in a pair to find fidelities in the environment of hand-held graphing calculator. We concluded that the cognitive fidelity showed three different properties using "what if not" strategy which the mathematical fidelity between the representations supported. Also, the exploration using a calculator in the pedagogical fidelity strongly helped them to apply and to expand their learning.

• School Mathematics
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• v.12 no.4
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• pp.531-545
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• 2010

This research is focusing on find out the learning method for mathematics underachievers of middle school. The tested method were metacognitive activity through writing. For conducting research, I had selected mathematics underachievers of middle school. After selecting them, I made two group. One group studied using CAS calculator with paper and pencil. And another group studied using paper and pencil only. Both groups exhibited metacognitive learning activities. The analysis of result shows that the group with CAS calculator did better than the group of paper and pencil.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.643-650
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• 2014

A hardware implementation of phase calculator for extracting 3D depth image from TOF(Time-Of-Flight) sensor is described. The designed phase calculator adopts redundant binary number systems and a pipelined architecture to improve throughput and speed. It performs arctangent operation using vectoring mode of DCORDIC(Differential COordinate Rotation DIgital Computer) algorithm. Fixed-point MATLAB simulations are carried out to determine the optimal bit-widths and number of iteration. The phase calculator has ben verified by FPGA-in-the-loop verification using MATLAB/Simulink. A test chip has been fabricated using a TSMC $0.18-{\mu}m$ CMOS process, and test results show that the chip functions correctly. It has 82,000 gates and the estimated throughput is 400 MS/s at 400Mhz@1.8V.

• Communications of Mathematical Education
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• v.24 no.1
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• pp.177-193
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• 2010

The purpose of this study is to explore normal distribution in probability distributions of the area of statistics in high school mathematics. To do this these contents such as approximation of normal distribution from binomial distribution, investigation of normal distribution curve and the area under its curve through the method of Monte Carlo, linear transformations of normal distribution curve, and various types of normal distribution curves are explored with CAS calculator. It will not be ablt to be attained for the objectives suggested the area of probability distribution in a paper-and-pencil classroom environment from the perspectives of tools of CAS calculator such as trivialization, experimentation, visualization, and concentration. Thus, this study is to explore various properties of normal distribution curve with CAS calculator and derive from pedagogical implications of teaching and learning normal distribution curve.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.125-130
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• 1998

This paper describes a novel flux calculator for the estimation of real rotor flux angle which is indispensable to the field oriented control of induction motors. A pure integrator is used to estimate the real rotor flux precisely from voltage and current information. The proposed flux calculator adopts the new drift compensation method to overcome the drift problem of pure integrator. The motor speed is calculated using estimated flux angle and estimated slip frequency. The performance of this approach is verified through the experiment. The experimental results shows stable operation of proposed system even below 1/100 of rated speed.

• The Mathematical Education
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• v.42 no.5
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• pp.647-672
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• 2003

This study sought to determine the impact of the graphing calculator on prospective math-teachers' mathematical thinking while they engaged in the exploratory tasks. To understand students' thinking processes, two groups of three students enrolled in the college of education program participated in the study and their performances were audio-taped and described in the observers' notebooks. The results indicated that the prospective teachers got the clues in recalling the prior memory, adapting the algebraic knowledge to given problems, and finding the patterns related to data, to solve the tasks based on inductive, deductive, and creative thinking. The graphing calculator amplified the speed and accuracy of problem-solving strategies and resulted partly in students' progress to the creative thinking by their concept development.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.224-226
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• 1995

This paper presents an algorithm that the gain of the slip calculator is correctly adjusted for the variation of the rotor resistance. In the indirect field oriented controller, if the gain (rotor resistance) of the slip calculator is set the incorrect value, the torque and the flux are not properly controlled. Using of the two torque angles (i.e. stationary torque angle and rotating torque angle), we estimate the rotor resistance, and then adjust the gain of the slip calculator for the variation of the rotor resistance. It has been realized to confirm the validity of the proposed algorithm by the simulation results.

• Journal of Broadcast Engineering
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• v.16 no.1
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• pp.54-63
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• 2011

This paper proposes a new equation to calculate computer-generated hologram (CGH) in a high speed and its cell-based VLSI (veri large scale integrated circuit) architecture. After finding the calculational regularity in the horizontal or vertical direction from the basic CGH equation, we induce the new equation to calculate the horizontal or vertical hologram pixel values in parallel. We also propose the architecture of the CGH cell consisting of a initial parameter calculator and update-phase calculator(s) on the basis of the equation and implement them in hardware. Also we show a hardware architecture to parallelize the calculation in the horizontal direction by extending CGH. In the experiments we analyze the used hardware resources. These analyses makes it possible to select the amount of hardware to the precision of the results. Here, for the CGH kernel and the structure of the processor, we used the platform from our previous works.

• School Mathematics
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• v.18 no.1
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• pp.85-103
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• 2016

This study was to find characteristics of argumentation derived from a discourse in a math-gifted 5 grade class, which was held for finding a Pick's formula using Geoboard function of TI-73 calculator. For the analysis, a video record of the class, transcript of its voice record, and activity paper were used as data and Toulmin's argument schemes were applied as analysis standard. As a result of the study, we found that the graphing calculator helped the students to create an experimental environment that graphing a grid-polygon and figuring out its area. Furthermore, it also provided a basic demonstration through 'data->claim' composition and reasoning activities which consisted of guarantee, warrant, backing, qualifier and refutal for justifying. The basic argumentation during the process of deriving the Pick's theorem by the numbers of boundary points and inner points was developed into a 'collective argumentation' while a teacher took a role of a conductor of the argumentation and an authorizer on the knowledge at the same time.