• Journal of Information Science Theory and Practice
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• v.6 no.4
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• pp.39-53
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• 2018

While the body of research on metadata has grown substantially, there has been a lack of systematic analysis of the field of metadata. In this study, we attempt to fill this gap by examining metadata literature spanning the past 20 years. With the combination of a text mining technique, topic modeling, and network analysis, we analyzed 2,713 scholarly papers on metadata published between 1995 and 2014 and identified main topics and trends in metadata research. As the result of topic modeling, 20 topics were discovered and, among those, the most prominent topics were reviewed in detail. In addition, the changes over time in the topic composition, in terms of both the relative topic proportions and the structure of topic networks, were traced to find past and emerging trends in research. The results show that a number of core themes in metadata research have been established over the past decades and the field has advanced, embracing and responding to the dynamic changes in information environments as well as new developments in the professional field.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.39-45
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• 2020

The Cu/Cu2O/CuO photoelectrode has been successfully fabricated by Rapid Thermal Annealing technique. The structural characterization of fabricated photoelectrode was performed using X-Ray diffraction, while elemental composition of the prepared material has been checked with X-Ray Photoelectron Spectroscopy. The synthesis parameters are optimized on the basis of photoelectrochemical performance. The best photoelectrochemical performance has been observed for the Cu/Cu2O/CuO photoelectrode fabricated at 550 ℃ oxidation temperature and oxidation time of 50 seconds with highest photocurrent density of -3 mA/㎠ at -0.13 V vs. RHE.

• Steel and Composite Structures
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• v.38 no.3
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• pp.305-317
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• 2021

The mechanical behavior of the outer square inner circular concrete-filled dual steel tubular (SCCFT) stub columns under axial compression is investigated by means of experimental research, numerical analysis and theoretical investigation. Parameters such as diameter ratio, concrete strength and steel ratio were discussed to identify their influence on the mechanical properties of SCCFT short columns on the basis of the experimental investigation of seven SCCFT short columns. By establishing a finite element model, nonlinear analysis was performed to discuss the longitudinal and transverse stress of the dual steel tubes. The longitudinal stress characteristics of the core and sandwich concrete were also analyzed. Furthermore, the failure sequence was illustrated and the reasonable cross-section composition of SCCFT stub column was proposed. A formula to predict the axial load capacity of SCCFT stub column was advanced and verified by the results from experiment and the finite element.

• Structural Engineering and Mechanics
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• v.91 no.2
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• pp.149-161
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• 2024

In the world, the construction science and technology industry has developed strongly thanks to the application of Ultra-High Performance Concrete (UHPC) technology, with a strength greater than 150 Mpa and unprecedented durability. compared to previous materials. However, this technology can build special structures but has limited use in construction because it is not commercially feasible to replace regular concrete in most structural types due to material costs. high, lack of availability, limited design standards, complex manufacturing and maintenance techniques. This article examines the composition of UHPC materials and their performance in composite structures with conventional concrete, a promising choice for promoting the development of UHPC technology in construction. It is based on the combined use of UHPC as a covering layer around normal concrete or as an inner core to increase the strength of normal concrete, create a slender structure and reduce the cost and repair of construction works. Construction and transport infrastructure are degraded. Manufacturing costs are expected to be reduced with composite construction due to the advantages of combined materials.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1547-1554
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• 2017

VESTA (Verification of Ex-vessel corium STAbilization) and VESTA-S (-small) test facilities were constructed at the Korea Atomic Energy Research Institute in 2010 to perform various corium melt experiments. Since then, several tests have been performed for the verification of an ex-vessel core catcher design for the EU-APR1400. Ablation tests of an impinging $ZrO_2$ melt jet on a sacrificial material were performed to investigate the ablation characteristics. $ZrO_2$ melt in an amount of 65-70 kg was discharged onto a sacrificial material through a well-designed nozzle, after which the ablation depths were measured. Interaction tests between the metallic melt and sacrificial material were performed to investigate the interaction kinetics of the sacrificial material. Two types of melt were used: one is a metallic corium melt with Fe 46%, U 31%, Zr 16%, and Cr 7% (maximum possible content of U and Zr for C-40), and the other is a stainless steel (SUS304) melt. Metallic melt in an amount of 1.5-2.0 kg was delivered onto the sacrificial material, and the ablation depths were measured. Penetration tube failure tests were performed for an APR1400 equipped with 61 in-core instrumentation penetration nozzles and extended tubes at the reactor lower vessel. $ZrO_2$ melt was generated in a melting crucible and delivered down into an interaction crucible where the test specimen is installed. To evaluate the tube ejection mechanism, temperature distributions of the reactor bottom head and in-core instrumentation penetration were measured by a series of thermocouples embedded along the specimen. In addition, lower vessel failure tests for the Fukushima Daiichi nuclear power plant are being performed. As a first step, the configuration of the molten core in the plant was investigated by a melting and solidification experiment. Approximately 5 kg of a mixture, whose composition in terms of weight is $UO_2$ 60%, Zr 10%, $ZrO_2$ 15%, SUS304 14%, and $B_4C$ 1%, was melted in a cold crucible using an induction heating technique.

• Journal of the Korean Magnetics Society
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• v.21 no.2
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• pp.77-82
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• 2011

The use of soft magnetic materials have been increasing in the various industrial fields according to the increasing demand for high performance, automatic, miniaturing equipments in the recent our life. In this study, we investigated the effect of factors on the core loss and magnetic properties of electrical steel and soft magnetic composites. Furthermore, we reviewed the major efforts to reduce the core loss and improve the soft magnetic properties in the two main soft magnetic materials. Domain purification which results from reduced density of defects in cleaner electrical steels is combined with large grains to reduce hysteresis loss. The reduced thickness and the high electrical conductivity reduce the eddy current component of loss. Furthermore, the coating applied to the surface of electrical steel and texture control lead to improve high permeability and low core loss. There is an increasing interest in soft magnetic composite materials because of the demand for miniaturization of cores for power electronic applications. The SMC materials have a broad range of potential applications due to the possibility of true 3-D electromagnetic design and higher frequency operation. Grain size, sintering temperature, and the degree of porosity need to be carefully controlled in order to optimize structure-sensitive properties such as maximum permeability and low coercive force. The insulating coating on the powder particles in SMCs eliminates particle-to-particle eddy current paths hence minimizing eddy current losses, but it reduces the permeability and to a small extent the saturation magnetization. The combination of new chemical composition with optimum powder manufacturing processes will be able to result in improving the magnetic properties in soft magnetic composite materials, too.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.269-277
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• 2008

Amino acid composition in grain of Korean native rice core collections was evaluated to identify the useful genotypes for quality enhancing rice breeding and value-added food development. Large variations were found in the contents of 16 amino acids among 388 genotypes tested with 14.9% of the minimum coefficient of variation (CV), and the contents of methionine and histidine showed the highest CV and the second high, respectively. The average values of total amino acid, total essential amino acid, lysine and threonine contents of Korean native rice collections were almost similar with those of cultivating japonica rice, Saechucheong. Among 388 native core collections Baekkokna, Daesona and Saducho were identified as high amino acid germplasm in total amino acid, total essential amino acid, lysine and threonine contents. And Seoksanjo and Sodujo were identified as low amino acid collections. Rice collections showing purple apiculus color tended to distribute in lower serine, proline, glutamic acid, glycine, alanine, valine, leucine, phenylalanine, arginine, and total amino acid contents compared with those of yellowish apiculus color collections. The glutinous rice collections showed the tendency of higher contents of serine, glutamic acid, alanine, valine and leucine compared with those of non-glutinous collections.

• Journal of the Korean Society for information Management
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• v.40 no.2
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• pp.183-209
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• 2023

The purpose of this study is to evaluate the Dublin Core metadata generated by ChatGPT using book covers, title pages, and colophons from a collection of books. To achieve this, we collected book covers, title pages, and colophons from 90 books and inputted them into ChatGPT to generate Dublin Core metadata. The performance was evaluated in terms of completeness and accuracy. The overall results showed a satisfactory level of completeness at 0.87 and accuracy at 0.71. Among the individual elements, Title, Creator, Publisher, Date, Identifier, Rights, and Language exhibited higher performance. Subject and Description elements showed relatively lower performance in terms of completeness and accuracy, but it confirmed the generation capability known as the inherent strength of ChatGPT. On the other hand, books in the sections of social sciences and technology of DDC showed slightly lower accuracy in the Contributor element. This was attributed to ChatGPT's attribution extraction errors, omissions in the original bibliographic description contents for metadata, and the language composition of the training data used by ChatGPT.

• Journal of the Korean Society of Earth Science Education
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• v.17 no.1
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• pp.49-59
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• 2024

In this study, we investigated the philosophical background and progress of the 2022 revised curriculum development in the high school earth science field. Research that was not covered in the research report includes the relevance of the transformative competency of OECD Education 2030, and that core ideas and achievement standards are organized around knowledge understanding, process functions, and value attitudes that constitute the learning compass needle. In addition, the composition of core ideas and Earth science electives in light of the understanding-centered curriculum, and IB type inquiry-based teaching and learning. Main research results include that the 2022 revised Earth science curriculum emphasized the student agency to foster the transformative competency and scientific literacy, and the curriculum document system in the field of earth science uses a learning compass needle. In addition, based on the understanding-centered curriculum, core ideas of Earth science were derived, and elective courses were organized to help students reach these core ideas. Also, IB-type inquiry-based teaching and learning was emphasized to foster student agency with knowledge construction competency. Based on the research results, slimming of the national and general level curriculum, the need to develop process-centered assessment methods for value and attitudes, the need for curriculum backward design, and ways to develop student agency through inquiry-based teaching and learning were suggested.

• Journal of the Korean Magnetics Society
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• v.16 no.5
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• pp.255-260
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• 2006

The basic composition of Ni-Zn ferrite was $(Ni_{0.35}Cu_{0.2}Zn_{0.45})_{1.02}(Fe_2O_3)_{0.98}$ (group A) and $(Ni_{0.4}Cu_{0.2}Zn_{0.4})_{1.02}(Fe_2O_3)_{0.98}$(group B) with additional 0.1 mol% $CaCO_3$ and 0.03 mol% $V_2O_5$. For high permeability and acceleration of grain growth, $CaCO_3$ and $V_2O_5$ was added. The mixture of the law materials was calcinated at $600^{\circ}C$ for 2 hours and then milled. The compacts of toroidal type were sintered at different temperature ($1,050^{\circ}C,\;1,070^{\circ}C,\;1,100^{\circ}C$) for 2 hours in air followed by an air cooling. Then, effects of various composition and sintering temperatures on the microstructure and physical properties such as density, resistivity, magnetic induction, coercive force, initial permeability, quality factor, and curie temperature of the Ni-Zn ferrite were investigated. The density of the Ni-Zn ferrite was $4.90{\sim}5.10g/cm^3$, resistivity revealed $10^8{\sim}10^{12}{\Omega}-cm$. The average grain size increased with the increase of sintering temperatures. The magnetic properties obtained from the aforementioned Ni-Zn ferrite specimens were 4,000 gauss for the maximum induction, 0.25 oersted for the coercive force, 2,997 for the initial permeability, 208 for the quality factor, and $202^{\circ}C$ for the curie temperature. The physical properties indicated that the specimens could be utilized as the core of microwave communication and high permeability deflection yoke of high permeability.