• 한국지구과학회:학술대회논문집
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• 2004.02a
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• pp.18-19
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• 2004

• Journal of The Korean Association For Science Education
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• v.30 no.7
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• pp.901-907
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• 2010

The purpose of this study is to analyze methods for measuring the size of the Earth, put forth in 6 different Korean 8th grade science textbooks. The research questions are as follows: 1) Do they adequately map out the experiments for measuring the size of the earth by using the concept of the sun's altitude? 2) Do they reduce the size of the sun like as the Earth is similarly downsized to the globe? 3) Do they suggest the precise experimental conditions for selecting two equal longitudinal spots for measuring the size of the earth? 4) Do they design adequate experiments for exact measurement? 5) Do they offer a proportional expression for seeking the size of globe which is easily understood by students? 6) Do they develop experiments to measure actual size of the earth? Four graduate students and one researcher took part in this study. All conditions were unanimously agreed upon by the participants. The results are as follows. First, one publishing company must include the concept of the sun's altitude to accurately measure the size of the Earth. However, some textbooks fail to mention this. As such, the concept of the sun's altitude must be introduced to accurately measure the size of the Earth. Second, a reduced size globe is used as the actual earth so; the sun should be factored in with a reduced light value. Third, you have to lay a stress on two points at the same longitude. In other words, a shadow located at the same longitude from two randomly selected points. Most textbooks mention two points at the same longitude but two of them design the experiment with a shadow at the same longitude. Fourth, we need a method to precisely measure the angle between a stick and its shadow. The angle between the stick and the tip of its shadow is the sun's altitude difference. Fifth, we need to present more specific proportional expressions for calculating the size of the globe. Only 3 out of the 6 texts employed a proportional expression. Sixth, we need to calculate the size of the earth by accurately presenting the scale of the globe to attain the goal of the experiment. Two of the texts analyzed, designed the experiment for the purpose of calculating the size of the globe. Three of the texts designed their experiments to calculate the radius of globe which is not even relevant to the purpose of experiment.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.161-167
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• 2014

This paper describes reinforcement method of reinforced earth wall near the abutment. The excessive displacement of a case affected by reduction of bearing capacity due to macro-environment condition like a coast. That is, the front displacement of reinforced earth wall has been happening continuously due to strength reduction of foundation ground. The micro pile is applied to reinforcement method, in order to secure a bearing capacity and global slope stability of reinforced earth wall. The results of numerical analysis confirmed that reinforcement method based on micro pile can secure a stability of structure, while the reconstruction of reinforced earth wall is impossible by construction and macro-environment condition.

• Journal of the Korean Society of Earth Science Education
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• v.3 no.3
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• pp.219-227
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• 2010

The purpose of this study was to investigate the effect of science journal writing on science-related attitude and science academic achievement of elementary school students in order to find out the value of science journal writing. For this purpose, one class of 6th graders was tested. The result of this study were as follows: First, Science journal are classfied by forms and content. The most frequently used types are prose and organizing concept. Second, Science journal writing brought positive effects on science - related attitude, especially cognition of science. Third, Science journal writing has positive effect on science academic achievement. Therefore Science Journal Writing can be useful method in Science education.

• Archives of Metallurgy and Materials
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• v.64 no.3
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• pp.953-957
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• 2019

U-10wt.%Zr metallic fuel slugs containing rare-earth (RE: a rare-earth alloy comprising 53% Nd, 25% Ce, 16% Pr and 6% La) elements for a sodium-cooled fast reactor were fabricated by modified injection casting as an alternative method. The distribution, size and composition of the RE inclusions in the metallic fuel slugs were investigated according to the content of the RE inclusions. There were no observed casting defects, such as shrunk pipes, micro-shrinkage or hot tears formed during solidification, in the metallic fuel slugs fabricated by modified injection casting. Scanning electron micrographs and energy-dispersive X-ray spectroscopy (SEM-EDS) showed that the Zr and RE inclusions were uniformly distributed in the matrix and the composition of the RE inclusions was similar to that of a charged RE element. The content and the size of the RE inclusions increased slightly according to the charge content of the RE elements. RE inclusions in U-Zr alloys will have a positive effect on fuel performance due to their micro-size and high degree of distribution.

• Mass Spectrometry Letters
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• v.12 no.4
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• pp.186-191
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• 2021

A new method for chemical separation of light rare-earth elements (LREEs) using gas-pressurized extraction chromatography (GPEC) is described. GPEC is a microscale column chromatography system that features a constant flow of solvents, which is created by pressurized nitrogen gas. The separation column with a Teflon tubing was packed with LN resin. The proposed GPEC method facilitates production of lesser chemical wastes and faster separation owing to the use of low solvent volume compared to traditional column chromatography. We evaluated the separation of Ba, La, Ce, and Nd using various elution solvents. The column reproducibility of the proposed GPEC system ranged from 2.4% to 4.9% with RSDs of recoveries, and the column-to-column reproducibility ranged from 3.1% to 6.3% with RSDs of recoveries. The proposed technique is robust, and it can be useful for the fast separation of LREEs.

• Journal of the Korean earth science society
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• v.31 no.2
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• pp.164-171
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• 2010

The purpose of this study was to investigate the effects of instruction applying 3D Planetarium Software (Starry Night Pro 6.0) in terms of the learners' science achievement, changes of attitude (attitude toward science as well as scientific attitude), and self-directed learning ability. Participants were 198 $8^{th}$ graders. This study adopted a quasi-experimental research design in which experimental group was taught with 3D planetarium software vs. control group with traditional lecture-centered teaching method for 6 hours. The effects were investigated by independent sample t-test and paired sample t-test The results are as follows. The instruction using 3D planetarium software was more effective than the traditional lecture-centered curriculum in science achievement and self-directed learning ability. However, there were not meaningful differences in analyzing attitudes related science, the results that were so effective in elevation for self-directed learning could be gained. Students were interested in instruction applying 3D planetarium software, which was helpful for them to understand the content knowledge. Results showed that instruction with 3D planetarium software applied was effective in $8^{th}$ grade science learning.

• Journal of Astronomy and Space Sciences
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• v.13 no.1
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• pp.19-31
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• 1996

We have analyzed collected photoelectric light curves for light variations of SW Lac. The method of Fourier analysis was adopted to quantify the light variation from season to season. We found the linear relation between the Fourier coefficient, B1 and the magnitude difference between two maxima. The total light of the system has been decreased as much as 0m.04 during approxiamately 20 years time interval. Photoelectric parameters including spot parameters for all light curves were obtained by the method of the Wilson and Devinney differential correction in order to secure the variations of parameters from season to season. SW Lac, not like RS CVn type stars, required to adjust all parameters as well as spot parameters for a reasonable fit to the observations of each epoch. A surface temperature of cooler star is one of the most sensitive parameters to affect a shape of light curve of SW Lac. We conclude that the shape of light curve of SW Lac varies even during one season as well as season to season. The light curve is mainly caused by inhomogeneous surface temperature due to strong chromospheric activity of the system.

• Journal of Conservation Science
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• v.5 no.2 s.6
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• pp.25-34
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• 1996

The essential point to be considered when restoring lacquered ware is to know its materials and properties, and prior studios from the conservational and scientific examination is the way to achieve it. Recently, to get a close examination of its materials and methods involved in lacquered ware making, cross section microscope studies are being applied. Cross section microscope studies shows that lacquering process has been simplified and that bone and earth substances have been added to the materials, a method also traced from the lacquered wooden coffin excavated from the 'Nak Rang Tomb' and by the lacquered wares of the 'Kyongjoo An Ap' areas. The significance of this Chosun Dynasty lacquered wares's inlaid with mother-of pearl restoration can be found in that we have been able to harmonize the very traditional and the very modern scientific method of our time and that we were able to launch a step forward from using only the synthetics to open up a new range of natural materials such as lacquers, bone and earth substances, oxhide-glue and nacres and of referring to the traditional methods.

• Journal of Magnetics
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• v.18 no.3
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• pp.308-310
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• 2013

Translation induced by the field-gradient force is being observed for a single ferromagnetic iron grain and a ferrimagnetic grain of a ferrite sample ($CuFe_2O_4$). From measurements on the translation, precise saturated magnetization of $M_S$ is possible for a single grain. The method is based on the energy conservation rule assumed for the grain during its translation and the grain is translated through a diffuse area under microgravity conditions. The results of the two materials indicate that a field-induced translation of grain bearing spontaneous moment is generally determined by a field-induced potential $-mM_SH(x)$ where m denotes the mass of sample. According to the above translations, the detection of $M_S$ is not interfered by any signals from the sample holder. The $M_S$ measurement does not require m value. By observing translations resulting from fieldinduced volume forces, the magnetization of a single grain is measurable irrespective of its size; the principle is also applicable to measuring susceptibility of diamagnetic and paramagnetic materials.