• East Asian mathematical journal
• /
• v.26 no.2
• /
• pp.281-299
• /
• 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)
• /
• v.15 no.3
• /
• pp.1015-1029
• /
• 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.

• Research in Mathematical Education
• /
• v.19 no.1
• /
• pp.81-88
• /
• 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
• /
• 1991.10b
• /
• pp.1904-1909
• /
• 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.

• Journal of the Korean Society for Precision Engineering
• /
• v.32 no.4
• /
• pp.345-351
• /
• 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.

• Journal of Biomedical Engineering Research
• /
• v.30 no.4
• /
• pp.279-287
• /
• 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
• /
• v.33 no.7
• /
• pp.1003-1011
• /
• 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.

• Journal of Elementary Mathematics Education in Korea
• /
• v.11 no.2
• /
• pp.99-115
• /
• 2007

The purpose of this study was to look into whether this mathematising learning utilizing realistic context has an effect on the mathematical thinking. To solve the above problem, two 5th grade classes of D Elementary School in Seoul were selected for performing necessary experiments with one class designated as an experimental group and the other class as a comparative group. Throughout 17 times for six weeks, the comparative group was educated with general mathematics learning by mathematics and "mathematics practices," while the experimental group was taught mainly with mathematising learning using realistic context. As a result, to start with, in case of the experimental group that conducted the mathematising learning utilizing realistic coherence, in the analogical and developmental thoughts which are mathematical thoughts related to the methods of mathematics, in the thinking of expression and the one of basic character which are mathematical thoughts related to the contents of mathematics, and in the thinking of operation, the average points were improved more than the comparative group, also having statistically significant differences. The study suggested that it is necessary to conduct subsequent studies that can verify by expanding to each grade, sex and region, develop teaching methods suitably to the other content domains and purposes of figures, and demonstrate the effects. In addition to those, evaluation tools which can evaluate the mathematical thinking processes of children appropriately and in more diversified methods will have to be developed. Furthermore, in order to maximize mathematising for each group in each mathematising process, it would be necessary to make efforts for further developing realistic problem situations, works and work sheets, which are adequate to the characteristics of the upper and lower groups.

• Communications of Mathematical Education
• /
• v.24 no.3
• /
• pp.611-626
• /
• 2010

The purpose of this study is to explore the composite properties of linear functions using CAS calculators. The meaning and processes in which technological tools such as CAS calculators generated to instrument are reviewed. Other theoretical topic is the design of an exploring model of observing-conjecturing-reasoning and proving using CAS on experimental mathematics. Based on these background, the researchers analyzed the properties of the family of composite functions of linear functions. From analysis, instrumental capacity of CAS such as graphing, table generation and symbolic manipulation is a meaningful tool for this exploration. The result of this study identified that CAS as a mediator of mathematical activity takes part of major role of changing new ways of teaching and learning school mathematics.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.13 no.8
• /
• pp.651-657
• /
• 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.