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Electrodeposition of pure Sn electrodes with various structures and their electrochemical performances for Na-ion batteries
No full textMetal-ion substitution for the utilization of high voltage V5+/V4+ redox couple in Na3V2(PO4)3 cathode materials of Na-ion batteries
No full textAn Sb/Sb2O3 composite prepared by electrochemical synthesis method as high capacity anode materials for Na-ion batteries
No full text나트륨 이온 전지용 양극소재에 ( and ) 적용되는 탄소 복합체 및 금속이온 치환이 소재의 전기화학적 특성에 미치는 영향
No full text학위논문(박사) - 한국과학기술원 : 신소재공학과, 2018.2,[vii, 101 p. :]Recently, Na-ion batteries have been considered as alternatives for Li-ion batteries due to the crustal abundance and low cost of Na. Therefore, it is necessary to develop electrode materials with high electrochemical performances to commercialize the Na-ion batteries. Especially, development of high-performance cathode materials is necessary which occupy the most part of the manufacturing cost. Cathode materials which have been extensively studied for Na-ion batteries are classified into layered oxides and polyanionic compounds according to their crystal structure. Among the various layered oxides, sodium manganese oxide has been considered potential cathode material due to its high capacity and cost-effective synthetic process. Among the polyanionic compounds, sodium vanadium phosphate (Na₃ V₂(PO₄)₃) have received attention owing to the excellent thermal and structural stability. However, the promising candidates of cathode materials for Na-ion batteries also have problems as follows: (1) sluggish kinetic properties of , (2) poor electronic conductivity and (3) low energy density of Na₃ V₂(PO₄)₃. Herein, three individual studies are performed to solve these problems. In the first part, composite cathode material is fabricated by simple heat treatment for high-power Na-ion batteries. Compared to only 28.07% retention of pristine , 64.55% of the discharge capacity of at a current density of 20 mA is retained at . The second part covers fabrication of high-power Na₃ V₂(PO₄)₃/C composite cathode materials by synergetic effects of sucrose coating and cellulose template. The improved rate performance of Na₃ V₂(PO₄)₃/C, at 20-C rate, is acquired from the cost-effective synthetic process with the relatively low amount of carbon, 5 wt.%. In the third chapter, Mg-substituted Na₃ V₂(PO₄)₃/C is synthesized to improve the energy density of Na₃ V₂(PO₄)₃ by utilization of redox reaction. The high-voltage redox reaction in Mg-substituted Na₃ V₂(PO₄)₃/C electrode leads to 3.5% increase of energy density compared with Na₃ V₂(PO₄)₃/C electrode.한국과학기술원 :신소재공학과
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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