• Journal of Pharmaceutical Investigation
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• v.38 no.1
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• pp.23-29
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• 2008

Red ginseng is made of white ginseng through the steaming and drying procedure. In this process, the amounts of toxic elements of ginseng are decreased and those of effective components, ginsenosides are increased. In order to identify the components alteration of white ginseng by processing time, we applied HPLC-based metabolomics approach combined with the principal component analysis (PCA) multivariate analysis. White ginsengs were steamed at 0, 1, 2, 4, 8 and 16 h, respectively and followed by drying process at moderate temperature. Then the steamed ginsengs and the commercial red ginsengs were analyzed by HPLC. On the basis of HPLC results, PCA multivariate analysis was applied for evaluating the quality of red ginseng, which showed the processed ginsengs are grouped by processed time because less polar ginsenosides were increased in proportion as the steaming time was increased. The purchased red ginsengs were distributed in the range of $0{\sim}1$ hour steaming time. This pilot experiment suggests that HPLC-based metabolomics approach is able to allow the quality of herbal medicines to be controlled with a simple and economic method.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.138-147
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• 2008

$SiO_2/TiO_2/ZrO_2$ broadband anti-reflective multi-layer thin films were prepared at room temperature by RF sputtering system. Optical constants and structural properties on each layer of films were analyzed by spectroscopic ellipsometer and transmittance spectra of the films were measured by $UV-V_{is}$ spectrophotometer in the range of 300$\sim$900 nm. To evaluate the films, we compared the measured and analyzed spectra with designed spectra. We investigated influence of discrepancy of thickness and refractive indices of each layer on changes of the transmittance spectra. It was found that refractive indices and shape of dispersion of deposition materials are more contributed to changes of the transmittance spectra than thickness of layer.

• Journal of the Korean Chemical Society
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• v.60 no.4
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• pp.239-244
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• 2016

We investigated the structures and electronic properties of Cu_mSiO_m+1 clusters with m = 0 - 7. For these clusters, we replaced a Cu atom in the copper oxide clusters with a Si atom. The B3LYP functional and LANL2DZ basis set were used for optimization of the molecular structures of all neutral and charged clusters. The bond distances, bond angles, and Mulliken charges were calculated to study the structural properties. In addition, in order to understand the electronic properties, we examined the ionization energies, electronic affinities, and second differences in energies.

• Communications of Mathematical Education
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• v.24 no.3
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• pp.659-689
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• 2010

Taxicab distance function is a practical distance notion which gives us information of real world pathway distance that really taxi can go through. As one of the non-Euclidean geometry, this study of an ideal city with all roads running horizontal or vertical, was introduced by the Russian Mathematician H. Minkowski and synthetically reported by the E. F. Kraus in 1986. After that, there were many reports and papers on this topic and still being researched. At this point of view, our research about taxicab geometry provides its differences from Euclidean plane geometry, and considers about several theorems on plane geometry using the taxicab distance function.

• Journal of Gifted/Talented Education
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• v.25 no.2
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• pp.339-358
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• 2015

This study was to examine perceptions of information technology(IT) competencies among gifted and non-gifted students(i.e., information science high school students and technical high school students). Of the 370 high school students surveyed from 3 high schools(i.e., gifted academy, information science high school, and technical high school) in three metropolitan cities, Korea, 351 students completed and returned the questionnaires yielding a total response rate of 94.86%. High school students recognized the IT professional competence as being most important when recruiting IT employees. And they considered that practice-oriented education was the most importantly needed to improve their IT skills. In addition, the most important sub-factors of IT core competencies among gifted academy students and information science high school students were basic software skills. Also Technical high school students responded that the main network and security capabilities were the most importantly needed to do so. Finally, the most appropriate training courses for enhancing IT competencies were recognized differently among gifted and non-gifted students. Gifted academy students responded that the 'algorithm' was the mostly needed for enhancing IT competencies, whereas information science high school students responded that 'data structures' and 'computer architecture' were mostly needed to do. For technical high school students, they responded that a 'programming language' course was the most needed to do so. Results are discussed in relations to IT corporate and school settings.

• The Journal of the Petrological Society of Korea
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• v.14 no.1
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• pp.61-72
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• 2005

The granitoids in the Mt. Geumjeong, Busan can be divided into granodiorite, hornblende granite, adamellite, tonalite, biotite granite and micrographic granite. The geochemical characteristics of the Mt. Geumjeong granites indicate that they were crystallized from a calc-alkaline series and that they belong to Ⅰ-type granitic rocks which evolved from granodioritic magma into hornblende granite, adamellite, biotitie granite, and finally micrographic granite through fractional crystallization of plagioclase. The crystallization pressures and temperatures of the minimum melt compositions of the granitic rocks were estimated to about 1∼5 kbar and 720∼700℃. The trace element composition and REE patterns, characterized by a high LILE/HFSE ratio and enrichments in LREE, indicate typical continental margin arc calc-alkaline rocks produced in the subduction environment. The Rb-Sr isotopic data for the Mt. Geumjeong granites define a well-defined isochron yielding as age of 69.6±1.9 Ma with an initial Sr isotopic ratio of 0.70503.

• Journal of Science Education
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• v.46 no.1
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• pp.93-108
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• 2022

The purpose of this study is to develop a STEAM program that can be used in the high school credit system to be fully implemented in 2025, and to examine its validity and effectiveness. The STEAM program analyzed the 2015 revised curriculum centering on science, technology, and engineering through the 2015 revised curriculum analysis, and then selected the five latest issues: hydrogen fuel, climate crisis, data science, appropriate technology, and barista. In accordance with this self-developed program development format (frame), it was developed for seven months through a process of group deliberation. The draft of the STEAM program for 29 sessions of five types, developed to indirectly experience the career path and occupation of high school students, was verified through consultation with 2 STEAM education experts. It was applied at five different high schools for a pilot implementation. As a result of the pilot application, it was confirmed that the students' STEAM attitude significantly improved in the post-test than the pre-test, and the students' high satisfaction with the program was confirmed. In addition, through an interview with the pilot application teacher, it was positively evaluated that 'the content and level of the program are suitable and through experience solving real-life problems, you can apply the content knowledge of related subjects and have an opportunity to experience careers.' Based on the results of the pilot application, the high school credit system STEAM program for students and teachers was finally completed in 29 lessons of five types. Through this study, the development and operation of the next-generation STEAM program that can be applied in the high school credit system should be actively developed, and a plan to improve teachers' professionalism so that the high school credit system can be established and operated properly for blended classes triggered by COVID-19. The necessity of design was suggested. This study is expected to be used as basic data for the development and operation of STEAM programs in the high school credit system, which will be fully implemented in 2025.

• Journal of The Korean Association For Science Education
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• v.24 no.2
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• pp.234-240
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• 2004

The main purpose of this study was to examine the effects of interpretive style reading materials on high school students philosophical viewpoints on science. Subjects for this study were 137 girl students in four classes of a high school located in Daejeon city. The classes were divided into two groups: experimental groups and control groups. Students in the experimental groups were administered a series of the reading materials over thirty-six sessions. Additionally, PPP(Philosophical Perspectives Prove) was used in order to assess students philosophical viewpoints on science. Results of the study showed that the interpretive style reading materials takes effect on the change of students philosophical viewpoints on science. At the initial stage, a number of students exhibited viewpoints inclined toward inductivism. As time goes by, however, viewpoint of inductivism was decreased and view of falcificationism and view of relativism were increased. The results also indicated that the effect of intervention was stable.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.393-398
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• 2014

A highly efficient dual-mode linear CMOS stacked-FET power amplifier (PA) is implemented for 3G UMTS and 4G LTE handset applications. High efficiency is achieved at a backed-off output power ($P_{out}$) below 12 dBm by employing an active-bypass amplifier, which consumes very low quiescent current and has high load-impedance. The output paths between high- and low-power modes of the PA are effectively isolated by using a bypass switch, thus no RF performance degradation occurs at high-power mode operation. The fabricated 900 MHz CMOS PA using a silicon-on-insulator (SOI) CMOS process operates with an idle current of 5.5 mA and shows power-added efficiency (PAE) of 20.5%/43.5% at $P_{out}$ = 12.4 / 28.2 dBm while maintaining an adjacent channel leakage ratio (ACLR) better than -39 dBc, using the 3GPP uplink W-CDMA signal. The PA also exhibits PAE of 35.1% and $ACLR_{E-UTRA}$ of -33 dBc at $P_{out}$ = 26.5 dBm, using the 20 MHz bandwidth 16-QAM LTE signal.

• Journal of The Korean Association For Science Education
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• v.12 no.3
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• pp.109-118
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• 1992

In this study, the attitudes of about 1200elementary and secondary students towards sciences lessons and scientists were investigated. For the survey of this study, simillar numbers of students in Seoul were selected from the 5th, 8th and 11th grades and from both sexes. For the attitudes towards science lessons, in the survey questionnaire, there were questions on the type of science lesson which students prefer and on student's assessment of science lessons which they receive. For the attitudes towards scientists, there were questions on scientists whom students respect, on students assessment of scientists and on students assessment of themselves. Results of this study can be summarized as follows: (1) A great majority of students prefered the laboratory-based to classroom-based lessons, but this tendency was less apparent in olderstudents.More boys, compared with girls, prefered laboratory-based study. (2) The student's assessment of science lessons was positive in the elementary school, neutral in the middle school and negative in the high school level. Boys showed more positive attitudes towards the study of science. (3) Apparently more girls than boys mentioned Madam Curie as a scientist whom they respect, Students tended to respect scientists in terms of their personalities rather than their cognitive abilities. (4) Students tended to assess that scientist's are more able than themselves in cognitive areas while themselves are better in affective areas. The gap between student's asessments of scientists and that of themselves became bigger in high school students. The gap between boy's assessments of themselves and girl's assessments of themselves was bigger in high school level than in middle school. (5) The decline of students attitude towards science lessons was bigger than their attitude towards scientists.