• Journal of The Korean Association For Science Education
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• v.15 no.1
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• pp.92-103
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• 1995

Since the late of 1960,s, the improvement of science inquiry skills has been one of the most important goals in secondary science education. To achieve this goal, it is essential to develop a valid and reliable instrument for evaluating science inquiry skills. The purpose of this study is to develop a valid and reliable instrument for evaluating science inquiry skills for high school students. The instrument is developed through R & D procedure, which includes two field trials of the instrument. This study has formed a clear definition of the elements of science inquiry skills (formulating a hypothesis, controlling variables, designing an experiment, numeric calculation, graphing experimental data, inference, determining relationship, determining causalities, predicting experimental results , drawing a conclusion, formulating a generalization or model), and established the goals of assessment and developed the items of assessment. The instrument, Test of Earth Science Inquiry Skills, consists of 33 items which measure 11 science inquiry skills. There are content-free items for each science inquiry skills. This study has selected 11 science inquiry skills which are considered appropriate for being evaluated by paper-and-pencil test with SIEI (Hur,1984). The content validity of items, objectivity of the scoring keys and clarity of the items were checked by six experienced specialists in science education. At the same time, the two field trials has been executed and produced the reliability of the instrument, item difficulty index, and the effectiveness of distracters. The first field trial was performed using a sample of 304 high school students, and the second one using a sample of 872 high school students. Because the content validity is 84 % and the reliability (K-R 20) is 0.84, the developed instrument in this study is considered valid and reliable. The difficulty index is 49.4 %, answer ratio 59.1 %, the discrimination index 0.47 and the effectiveness of distracters evenly distributed, which also suffice the criteria of good instrument. The developed instrument in this study can diagnosis the well-developed science inquiry skills and the ill-developed science inquiry skills of the students, and trace the degree of the improvement of science inquiry skills.

• Electrical & Electronic Materials
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• v.16 no.9
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• pp.64.1-64
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• 2003

A metal-ferroelectric [SrBi$_2$Ta$_2$O$\_$9/ (SBT)-high-k-insulator(PrOx)-semiconductor(Si) structure has been fabricated and evaluated as a key part of metal-ferroelectric-insulator-semiconductor-field-effect-transistor MFIS-FET memory, aiming to improve the memory retention characteristics by increasing the dielectric constant in the insulator layer and suppressing the depolarization field in the SBT layer. A 20-nm PrOx film grown on Si(100) showed both a high of about 12 and a low leakage current density of less than 1${\times}$ 10e-8 A/$\textrm{cm}^2$ at 105 MV/cm. A 400-nm SBT film prepared on PrOx/Si shows a preferentially oriented (105) crystalline structure, grain size of about 130 nm and subface roughness of 3.2 nm. A capacitance-voltage hysteresis is confirmed on the Pt/SBT/PrOx/Si diode with a memory window of 0.3V at a sweep voltage width of 12 V. The memory retention time was about 1 104s, comparable to the conventional Pt/SBT/SiO$\_$x/N$\_$y/(SiO$\_$N/)/Si. The gradual change of the capacitance indicates that some memory degradation mechanism is different from that in the Pt/SBT/SiON/Si structure.

• Proceedings of the Korean Vacuum Society Conference
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• 1997.07a
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• pp.35-35
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• 1997

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3213-3214
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• 2011

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2002.01a
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• pp.15-15
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• 2002

• Archives of Metallurgy and Materials
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• v.67 no.4
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• pp.1543-1546
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• 2022

The aluminum composite with dispersed high entropy alloy were developed by stir casting involving the powder-in-tube method. First, Al_0.5CoCrCuFeNi high entropy alloy (HEA) powder was made by mechanical alloying, and the powder was extruded in a tube-type aluminum container to form HEA precursor. The extruded HEA precursor was then dispersed in the aluminum matrix via stir casting. As a result, Fe-Cr-Ni based high-entropy phases was uniformly formed in the aluminum matrix, revealing ~158, 166, 235% enhancement of tensile strength by incorporating 1, 3, and 5 wt% HEA particles, respectively.

• Journal of The Korean Association For Science Education
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• v.17 no.1
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• pp.65-73
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• 1997

The purpose of this study is to develop a valid and reliable instrument, applicable to high school Earth Science class experiment. In advance of developing items, I was selected 14 inquiry process skills and specified evaluative objectives for each of them to develop scales and criteria for them. I developed 28 evaluation items for 5 experiment subjects among those of high school Earth Science class. The first field trial was performed a sample of 5 high school students, and the second one using a sample of 25 high school students. The results are as follows. (1) The content validity and reliability(Cronbach $\alpha$) of the developed items were 82.7% and .86, respectively, the developed instrument in this study is considered valid and reliable. (2) The average difficulty index was .69 and the discrimination index was .30. (3) Answer sheets based on the reported results were rated 5 teachers and Inter-rater Reliabilitiy and Inter-rater Consistency were analyzed, its indices were .80 and .76, respectively. (4) The developed items show a low coefficient of .45 with TESIS, a set of paper-and-pencil test items developed by Lee, Hang-Ro(1991). That the experiment assessment is solely subject to the rater's viewpoint has been one of the major problems raised concerning the matter. This research, however, shows that a set of more specified scales and criteria for the evaluation will make it more valid, reliable and efficient.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.298-303
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• 2012

$Y_{1-x}VO_4:Eu_x^{3+}$ red phosphors were synthesized with changing the mol ratios of $Eu^{3+}$ ions by using the solid-state reaction method. The crystalline structure of phosphors was found to be a tetragonal system with the maximum diffraction intensity at $25.02^{\circ}$. The grain particles showed the truncated hexagonal patterns with a very homogeneous size distribution at 0.05 mol of $Eu^{3+}$ ion. The excitation spectra of the phosphor ceramics were composed of a broad band centered at 303 nm and weak narrow multilines peaked in the range of 360-420 nm. The dominant emission spectrum was the strong red emission centered at 619 nm due to the $^5D_0{\rightarrow}^7F_2$ electric dipole transition. The experimental results suggest that the optimum doping mol ratio of $Eu^{3+}$ ions for preparing the red phosphors is 0.10 mol with the asymmetry ratio of 5.21.

• Journal of Science Education
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• v.34 no.2
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• pp.327-341
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• 2010

The purpose of this study is to obtain science high school students' perceptions of scientists and their work before and after the Green Investigation program with scientists. This study also attempts to determine whether the program affected the participants' perceptions of scientists and their work. A modified DAST was carried out with 64 high school students. Findings revealed that Korean science high school students had normal perceptions of scientists, such as images of 20 to 30 year old males wearing laboratory coats and working alone in research labs with test tubes, flasks, and several machines in the background. After the intervention, students drew fewer typical items representing scientists and had significantly different perceptions of their work places between the pretest (M=1.69, SD=1.14) and posttest (M=1.96, SD=1.24, t=4.43, p<0.001) with the eta squared statistics (.24). These findings reflect the need for continued efforts of developing green investigation programs with scientists for students. Some future studies based on this study are also introduced.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.2
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• pp.115-121
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• 2021

The evaluation of package temperature for fresh preservation of cucumber was investigated. The fresh cucumber is available in markets of Korea during whole seasons, for the help of farmer, distributor and consumer. Cucumbers were stored within cardboard boxes packaging covered with low density polyethylene (LDPE) at different temperatures (5, 10, 15 and 20℃). Changes in weight loss, hue angle, firmness, moisture content and general appearance (shape of cucumber) were investigated during storage of cucumbers. General appearance index with non-packaging decreased more than with LDPE film packaging at 5℃ and 10℃. During storage of cucumbers, general appearance index as freshness showed packaging effect at low temperature than room temperature. In the fresh weight loss, the packaged cucumbers were less reduced than that of the non-packaging ones. At color change, Hue angle of cucumber stored within low temperature with film packaging decreased gradually during storage. However remarkable change in hue angle were observed in cucumber within LDPE film packaging treatments of 15℃ and 20℃ storage. The effect of hue angle with packaging appears differently depending on the storage temperature conditions. The firmness and moisture content of cucumber flesh were not affected by packaging and storage temperature. In this experiment, cucumbers packaged with LDPE film at 5℃ and 10℃ were the most desirable for extending the quality. These results suggest that packaging of low temperature treatments in combination could be effective in prolonging the shelf life of cucumber.