• Journal of the Korean Ceramic Society
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• v.43 no.11 s.294
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• pp.710-714
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• 2006

Barium titanate nanoparticles were synthesized under N$_2$ atmosphere by the hydrolysis and condensation of barium hydroxide octahydrate and titanium (IV) isopropoxide. The synthesized particles were aggregates of nanosized primary particles. The primary particles of about 20-50 nm in diameter became building blocks of larger secondary particles, which are in most cases spherical in shape. The size and morphological evolution of secondary particles are strongly related to the precursor concentration. The observations suggest that formation and control of secondary particles is an essential step in the alkoxidehydroxide sol-precipitation process to obtain monodispersed barium titanate nanopowders.

• Journal of the Korean institute of surface engineering
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• v.55 no.1
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• pp.32-37
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• 2022

In a carbon-zero social atmospher, research is underway to reduce the use of fossil fuels. Interest in cleaner energy sources and their storage system is growing, and among them, research on effective energy storage is being actively conducted. Energy storage system(ESS) can be divided into secondary batteries, fuel cells, and capacitors, and the superiority of energy density of secondary batteries has a dominent influence on the ESS market. However, as problems with secondary batteries, charge/discharge speed, safety, and deterioration of electrodes are being highlighted. In this study, an electrode for supercapacitor with superior charge/discharge speed and specific capacitance is manufactured. The manufactured spinel nickel cobalt electrodes had specific capacitances of 1018.8 F/g, 690.8 F/g, and 475.1 F/g at 1 A/g in 1 M KOH electrolyte, and shows a performance retention rate of 77.48%, 63.30%, and 58.16% after 2000cycles at 7 A/g.

• Progress in Superconductivity
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• v.6 no.2
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• pp.124-128
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• 2005

Homogeneous and fine powders for Bi-2223 tape were prepared by ultrasonic spray pyrolysis (SP) method from an aqueous solution of metal nitrates. Bi-2223 precursor powders were synthesized with various solutes concentration and pyrolysis temperature. The synthesized precursor powders had a narrow particle size distribution and an average particle size was $\~{\cal}um$. The reactivity of precursor powder by SP method is very high, attributed to the fine and narrow particle size distribution. Bi-2223/Ag tape was prepared using PIT method and followed by various sintering conditions. The precursor powder by SP method promoted a very quick formation of the Bi-2223 phase for short sintering time while the secondary phase such as large AEC phase and $Ca_2PbO_4$ were minimized for SP tapes.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.110-113
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• 2012

Ge-S and Li-Ge-S powders were synthesized via solution-based process in order to employ chalcogenide-based solid electrolyte for use in Li secondary batteries. GeCl4 and thioacetamide in combination result in Ge-S powders of which major crystalline phase becomes GeS2 where the tetragonal and orthorhombic phases coexist after heat treatment. A chemical treatment using NaOH brings about the reduction of chlorine in the powders obtained. However, the heat treatment at 300 ℃ is more effective in minimizing the chlorine content. When lithium chloride is used as the precursor of Li ions, the LiCl powders are agglomerated with an inhomogeneous distribution. When Li2S is used, the Li-Ge-S powders are distributed more uniformly and the orthorhombic GeS2 phase dominates in the powders.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.108-108
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• 1994

• Hwankyungkyoyuk
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• v.20 no.3
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• pp.45-62
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• 2007

The purpose of this study was to analyze the status of environment-related teaching in elementary and secondary schools. A questionnaire survey was conducted for the study. Items in the questionnaire were developed based on the theory of environmental education and integrated education. The questionnaire was responded to 501 elementary school teachers, 273 middle school teachers, and 210 high school teachers in the city of Seoul and Kyunggi Province. The survey analysis revealed that elementary and secondary school teachers recognized 'environmental action skills' as the most important objective for school environmental education. Contrary to the teachers' expectations, it was found that there is insufficient teaching and learning materials for teaching in the domain of 'environmental action skills' and they could not confidently teach the skills in environment-related classes. For professional development of teachers in integrated environmental education, pre- and in-service programs will be developed systematically in a workshop to give teachers an opportunity to analyze teaching materials, design instruction plan, perform class trial, and evaluate the class situation for feedback. The results of this study can serve as a basic reference for improvement of environment-related subject education.

• Journal of Korean Home Economics Education Association
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• v.9 no.2
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• pp.31-45
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• 1997

The theoretical rationale and basic materials for the improvement of the recognition on home economics teachers are suggested in this study through the close examination of the teacher’s recognition and its related variables. For this study, review of literature and questionnaire survey were performed. As the results, the following may be suggested. 1. There teachers more experienced and non-majored the home economics or those who finished professional course should be reeducated adequately for new direction of home economics education in secondary school and new curriculum. 2. The development of qualification for home economics teacher and the educational system and program for training preliminary should be try to find a solution to improve the new and positive recognition of home economics education in secondary school. 3. The institutional and environmental conditions, such as pay and welfare facilities, should be improved to satisfy home economics teacher with new view of home economics education in secondary school with their duties. 4. The systematic and concrete teaching programs for contents of improving new recognition of home economics education in secondary school, and for promoting positive self-recognition as home economics teacher, and for training the abilities of developing teaching materials and guiding practical techniques should be developed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.6
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• pp.328-334
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• 2000

A lithium ion secondary battery using carbon as a negative electrode has been developed. Further improvements to increase the cell capacity are expected by modifying the structure of the carbonaceous material. There are hopes for the development of large capacity lithium ion secondary batteries with long cycle, high energy density, high power density, and high energy efficiency. In the present paper, needle cokes from petroleum were examined as an anode of lithium ion secondary battery. Petroleum cokes, MCL(Molten Caustic Leaching) treated in Korea Institute Energy Research, were carbonized at various temperatures of 0, 500, 700, $19700^{\circ}C$ at heating rate of $2^{\circ}C$/min for lh. The electrolyte was used lM liPF6 EC/DEC (1:1). The voltage range of charge & discharge was 0.0V(0.05V) ~ 2.0V. The treated petroleum coke at $700^{\circ}C$ had an initial capacity over 560mAh.g which beyond the theoretical maximum capacity, 372mAh/g for LiC6. This phenomena suggests that carbon materials with disordered structure had higher cell capacity than that the graphitic carbon materials.

• Resources Recycling
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• v.30 no.1
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• pp.3-13
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• 2021

In the secondary refining process for the production of high-grade steel, the proper composition is maintained by alloying elements, and non-metallic inclusions are controlled for high cleanliness. Complex reactions occur simultaneously between the molten steel, slag, inclusions, refractories, and alloying elements during the secondary refining process. Previous works have reported simulation models based on kinetics to predict the compositional changes in molten steel, slag, and inclusions in actual processes. Analytical reviews are required for the models to predict the process accurately. In this study, we reviewed and analyzed simulation models based on the coupled reaction model for the secondary refining process.

• International Journal of Knowledge Content Development & Technology
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• v.11 no.2
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• pp.7-21
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• 2021

The study was a descriptive cross-sectional survey which investigated the reading preferences of secondary school students in Nigeria during the lockdown occasioned by COVID-19 pandemic. A hundred secondary school students in Ile- Ife and Ilesa in Osun State, Nigeria were the study respondents. Close ended self-administered questionnaire was used to obtain data. Of the one hundred questionnaire which were applied to the study respondents, ninety-three were retrieved. Data obtained were analyzed using simple frequencies and percentages. The study established that majority of respondents were not pressured to read but read for pleasure. Preference for a wide range of fiction and non-fiction books which was read for purposes ranging from academic, social, relaxation and information was indicated by respondents. Availability of reading materials determined reading preference of majority of respondents as many could not afford to access electronic books whether free or not. The researchers recommended that different types of reading materials that suit the reading preferences and meet the diverse purpose of reading should be provided for the secondary school students during lockdown to improve their reading habits. Public libraries should function during this lock down period within the guidelines of the appropriate health authorities, while school libraries should be equipped to offer virtual services during the lockdown and the students should be exposed to e-books for their reading pleasure.