• Journal of Korean Elementary Science Education
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• v.35 no.4
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• pp.389-405
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• 2016

The purpose of this study was to analyze elementary school teachers' understanding, certainty, and familiarity with 13 key concepts of wave physics that are presented in textbook and teacher's guidebook. 123 elementary school teachers answered concept tests and questionnaires. In the results to these tests and questionnaires, teachers demonstrated a high level of understanding and high certainty in understanding with regard to the concepts of sound generation, effect of medium on wave, timbre, wavelength, and trough and crest of wave. For the topics of sound velocity, wave reflection and wave transmission, teachers demonstrated a high level of understanding but low certainty in understanding. With regard to sound propagation, teachers demonstrated a low level of understanding and an improperly high certainty in that low understanding. Teachers lacked knowledge, i.e., displayed a low level of understanding and low certainty in sound strength, sound frequency, constructive interference and destructive interference. In constructive and destructive interference, the teachers also displayed a low level of familiarity. We analyzed the differences in teacher's understanding, certainty, and familiarity according to teacher demographics defined by the teacher's gender, teaching experience with concepts of sound, career, curriculum track while in high school, and major in university. There were no significant differences in understanding, certainty, or familiarity as defined by gender, teaching experience, and career. However, these displays of knowledge were affected by the teacher's curriculum track in high school and their major. These results suggest that the teacher's understanding of, familiarity with, and certainty in wave physics concepts are more influenced by their learning experience than by their teaching experience. Therefore, we suggest additional learning opportunities for teachers (such as teacher training programs) in order to improve teacher knowledge and correct teacher misconceptions in wave physics.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1243-1251
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• 2020

Irradiation-induced damage of binderless nanoporous-isotropic graphite (NPIG) prepared by isostatic pressing of mesophase carbon microspheres for molten salt reactor was investigated by 3.0 MeV He⁺ irradiation at room temperature and high temperature of 600 ℃, and IG-110 was used as the comparation. SEM, TEM, X-ray diffraction and Raman spectrum are used to characterize the irradiation effect and the influence of temperature on graphite radiation damage. After irradiation at room temperature, the surface morphology is rougher, the increase of defect clusters makes atom flour bend, the layer spacing increases, and the catalytic graphitization phenomenon of NPIG is observed. However, the density of defects in high temperature environment decreases and other changes are not obvious. Mechanical properties also change due to changes in defects. In addition, SEM and Raman spectra of the cross section show that cracks appear in the depth range of the maximum irradiation dose, and the defect density increases with the increase of irradiation dose.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.06a
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• pp.272-273
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• 2003

Spin dynamics has been investigated intensively in various kinds of fields. Most popular one is an initial permeability at high frequency. Also, magnetic after-effect such as thermal fluctuation of fine magnetic particles and disaccommodation in soft magnetic materials were extensively studied in the past. When we apply an external farce with the same frequency as that of the system being examined, the system absorbs the external energy and the precession enhances. It is called resonance in general. Among the various resonances, ferromagnetic resonance (FMR) has been used as a good tool to evaluate material constants such as saturation manetization or spin damping parameter by analyzing a resonance curve. In this talk first instinctive understanding of Gilbert spin damping and spin pumping will be explained. Then, experimental data for enhancement of Gilbert damping parameter (G) evaluated from FMR spectrum and spin precession measured by a time resolved pump-probe method for Permalloy thin film will be introduced. Finally, magnetization reversal observed by air-coplanar probe will be given.

• Journal of The Korean Astronomical Society
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• v.41 no.3
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• pp.77-81
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• 2008

As a continuation of a previous work by Park et al. (2006), we have developed a two-element radio interferometer that can measure both the phase and amplitude of a visibility function. Two small radio telescopes with diameters of 2.3 m are used as before, but this time an external reference oscillator is shared by the two telescopes so that the local oscillator frequencies are identical. We do not use a hardware correlator; instead we record signals from the two telescopes onto a PC and then perform software correlation. Complex visibilities are obtained toward the sun at ${\lambda}\;=\;21\;cm$, for 24 baselines with the use of the earth rotation and positional changes of one element, where the maximum baseline length projected onto UV plane is ${\sim}\;90{\lambda}$. As expected, the visibility amplitude decreases with the baseline length, while the phase is almost constant. The image obtained by the Fourier transformation of the visibility function nicely delineates the sun, which is barely resolved due to the limited baseline length. The experiment demonstrates that this system can be used as a "toy" interferometer at least for the education of (under)graduate students.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.46.3-46.3
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• 2019

We present the control software and its development process for a prototype of the Camera and Grating Articulation System (CGAS) for GMACS, a wide-field, multi-object, moderate-resolution optical spectrograph for the Giant Magellan Telescope (GMT). The CGAS prototype is currently designed for the camera articulation controller as a miniature model of the GMACS. The camera articulation package (CAP) is a software that controls two stepper motors to adjust the camera angle. The package is developed using Visual C++ and runs on Windows 10. We discuss the architectural design and communication route between the high-end user software and the electronics hardware.

• Proceedings of the Korean Society of Medical Physics Conference
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• 1999.11a
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• pp.323-326
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• 1999

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.263-266
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• 2002

We have developed a practical method for estimating high-energy x-ray spectra using measured attenuation curves. This method is based on the iterative perturbation technique proposed by Waggener et al. The principle is to minimize the difference between the measured and calculated transmission curves. The experimental study was made using 4 MV, 10 MV, and 15 MV x-ray beams. It has been found that the spectrum varies strongly with the off-axis distance.

• Journal of The Korean Association For Science Education
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• v.34 no.7
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• pp.693-701
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• 2014

Based on social cognitive theory, self-efficacy in the context of learning has been steadily emphasized as an indicator of students' motivation and performance. The premise for developing such an instrument was that a specific measure of Physics self-efficacy was deemed to be an important predictor of the change processes necessary to improve students' physics understanding. In this study we described the process of developing and validating an instrument to measure students' beliefs in their abilities to perform essential tasks in physics and then investigated high school students' self-efficacy about physics learning and performance. Validity and reliability of PSEI were tested using various statistical techniques including the Cronbach alpha coefficient, exploratory factor analysis. The result of factor analysis supported the contention that the Physics Self-Efficacy Inventory (PSEI) was a multidimensional construct consisting of at least four dimensions: understanding and application of Physics concepts, achievement motivation, confidence for physics laboratory, confidence for Mathematics. The result showed that Kroean high schools students have low Physics self-efficacy for the all four dimensions. Therefore, researchers should focus on development of students' Physics self-efficacy. In addition, the instrument may lead to further understanding of student behavior, which in turn can facilitate the development of strategies that may increase students' aspiration to understand and study Physics. More specifically, by using the PSEI as a pre- and post-test indicator, instructors can gain insight into whether students' confidence levels increase as they engage in learning Physics, and, in addition, what type of teaching strategies are most effective in building deeper understanding of Physics concepts.where they freely exchanged opinions and feedback for constructing better collective ideas.

• Journal of the Korean Chemical Society
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• v.62 no.3
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• pp.214-225
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• 2018

In this study, we tried to find out how heat and thermal energy terms are defined and used in Korean science textbooks, and to see if there are any differences in the meaning of these terms used in different areas of science. For this purpose, the contents of 52 science textbooks of elementary, middle and high school published by the 2009 revised curriculum were analyzed. The definition of the term heat is given in the middle school Science(1) and the high school Physics I and II textbooks. Most textbooks define heat as "energy transferred due to a temperature difference (Type I)". Only one textbook of Physics I defines heat as "transfer of energy due to a temperature difference (Type II)". The definition of thermal energy is mostly presented in the middle school Science (2) and the high school Physics I textbooks. Physics I textbooks define the thermal energy as "molecular kinetic energy (Type III)", while Science(2) textbooks define it as Type I or "energy causes temperature change or phase transition of matter (Type IV)". In the texts of textbooks, heat is mainly used as the meaning of Type I or Type III. Thermal energy is mainly used as Type III, but it is also used as Type I in the high school Physics and Chemistry textbooks. The meanings of heat and thermal energy terms used are differed by the area of science. They are mainly used as type I or type III in Physics and Chemistry textbooks, and used as type III in Life Science and Earth Science textbooks.

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.50-50
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• 2004