• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.11a
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• pp.600-601
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• 2018

• Journal of the Korean Vacuum Society
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• v.14 no.2
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• pp.97-102
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• 2005

NO adsorption can be used in synthesizing oxynitride thin films which have potential application in nanodevices. However, it is very difficult to understand the oxynitridation Process since too many factors are involved in it. In this paper, we present our first-principles molecular dynamics calculation of the NO molecule adsorption on the Si(001) surface as the initial stage of the oxynitridation process. The previous first-principles calculation has argued the NO molecule is dissociated with a very small activation barrier, 0.07eV, which acutally corresponds to 1.60eV considering thermodynamics. This is in clear contrast to the observation that NO is dissociated at temperatures as low as 20K From extensive searches of NO on the Si(001) surface, we have found the new dissociation processes that have the much lower activation energies, less than 0.01 eV. We also present the dissociation and penetration processes with the corresponding activation energies and discuss their experimental implications.

• Journal of the Korean Magnetics Society
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• v.25 no.4
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• pp.101-105
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• 2015

Recent theoretical calculations predicted that a system composed exclusively of 3d transition metals without 4d/5d transition metals or rare earth metals can have strong perpendicular magnetocrystalline anisotropy (MCA) if Fe and Ni layers are arranged appropriately. They considered only Fe-terminated surfaces, noting that Fe/MgO(001) and CoFeB/MgO(001) show strong perpendicular MCA. In this paper, we investigate magnetism and MCA of Ni/Fe(001) surface where Ni layer is positioned at the surface, by using complementarily the first principles calculational methods of Vienna Ab-initio Simulation Package (VASP) and Full-potential Linearized Augmented Plane Wave (FLAPW) method. Comparing results of magnetism and MCA obtained by VASP with the results by FLAPW method, we find the VASP results do not show big difference from results by FLAPW method. Magnetic moments of Fe and Ni are enhanced due to strong hybridization between Fe and Ni bands. MCA of Ni/Fe(001) is parallel to the surface, which implies the surface termination plays a crucial role in determining MCA of a system.

• Journal of the Korean Magnetics Society
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• v.23 no.4
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• pp.117-121
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• 2013

In this study we investigated magnetism and magnetostriction of B2-structured FeX (X = Al, Si, Ni, Ga, Ge, and Sn) using a first-principles method, in order to survey the possibility of developing a transition metal based magnetostriction material. The Full-potential Linearized Augmented Plane Wave method was employed for solving the Kohn-Sham equation within the generalized gradient approximation for exchange-correlation interaction between electrons. FeX alloys are stabilized in ferromagnetic states except for the FeSi and FeGe alloys. Magnetostrcition coefficients of FeX (X = Al, Ni, Ga, and Sn) were calculated to be -5, +6, -84, -522ppm, respectively. It is noteworthy that the magnetostriction coefficient (-522ppm) of FeSn is larger than that (+400ppm) of Gafenol.

• Korean Chemical Engineering Research
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• v.61 no.4
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• pp.598-603
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• 2023

Electrochemical ammonia production using catalysts offers a promising alternative to the conventional Haber-Bosch process, allowing for ambient temperature and pressure conditions, environmentally friendly operations, and high-purity ammonia production. In this study, we focus on the nitrogen reduction reactions occurring on the surfaces of ruthenium catalysts, employing first-principles calculations. By modeling reaction pathways for nitrogen reduction on the (0001) and (1000) surfaces of ruthenium, we optimized the reaction structures and predicted favorable pathways for each step. We found that the adsorption configuration of N₂ on each surface significantly influenced subsequent reaction activities. On the (0001) surface of ruthenium, the end-on configuration, where nitrogen molecules adsorb perpendicularly to the surface, exhibited the most favorable N₂ adsorption energy. Similarly, on the (1000) surface, the end-on configuration showed the most stable adsorption energy values. Subsequently, through optimized hydrogen adsorption in both distal and alternating configurations, we theoretically elucidated the complete reaction pathways required for the final desorption of NH₃.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.645-645
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• 2013

Applying a first-principles computational approach combining density-functional theory and matrix Green's function calculations, we have studied the effects [2+2] cycloaddition olligormerization of fullerene $C_{60}$ chains on their junction charge transport properties. Analyzing first the microscopic mechanism of the switching realized in recent scanning tunneling microscope (STM) experiments, we found that, in agreement with experimental conclusions, the device characteristics are not significantly affected by the changes in electronic structure of $C_{60}$ chains. It is further predicted that the switching characteristics will sensitively depend on the STM tip metal species and the associated energy level bending direction in the $C_{60}-STM$ tip vacuum gap. Considering infinite $C_{60}$ chains, however, we confirm that unbound $C_{60}$ chains with strong orbital hybridizations and band formation should in principle induce a much higher conductance state. We demonstrate that a nanoelectromechanical approach in which the $C_{60}-STM$ tip distance is maintained at short distances can achieve a metal-independent and drastically improved switching performance based on the intrinsically better electronic connectivity in the bound $C_{60}$ chains.

• Journal of the Korean Society for Library and Information Science
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• v.50 no.2
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• pp.101-118
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• 2016

For the effective classification of complex subjects, a library classification scheme should adopt multiple division principles (or facets). Each of the multiple principles adopted for the division of complex subjects is sequentially applied at each stage of division. The order of application of these multiple principles during the process of division of complex subjects is called citation order. In order for a classification scheme to be consistent and logical, the citation order of division principles applied to classify complex subjects should be concrete and consistent. Especially, in case of enumerative classification system, decisions on citation order to represent complex subjects significantly affect the structure and organization of the classification system. There are basic principles and theoretical canons of the classification theory on the citation order and its application, but they cannot be applied solidly in the process of classification system development for practical reasons. Therefore, this paper first reviews previous works on classification theories regarding citation order, then explores the conditions and circumstances for the application of citation order.

• Korean Journal of Child Studies
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• v.13 no.1
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• pp.125-138
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• 1992

The purpose of the present study was to examine the development of embedding through relative clause formation in the first language acquisition of Korean. Results are reported from the study of the spantaneous natural speech of 36 young Korean children ranging from 16 months to 45 months in age acquiring Korean as their first language in Chinju, Korea. The results revealed a developmental order in the first language acquisition of Korean relative clause structures. Namely, a free or headless relative clause appears to be acquired first, before lexically headed restrictive relative construction. This order is consistent with one evidenced in English (and also Chinese) first language acquisition, 'free' relatives appear to provide a developmentally early stage in the acquisition of restrictive relative clauses. The Korean data provided additional evidence for an intermediary stage with an overt complementizer as well as an overt lexical head. Implications for the results are disscused with regard to a continuous theory of universal grammar in the first language acquisition.

• Journal of the Korean Society for Library and Information Science
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• v.46 no.2
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• pp.261-280
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• 2012

This study seeks to replace PaRIS Principles and find directions of revising KCR4 by analyzing the international Cataloging Principles 2009(ICP 2009) established in the environment of Machine Readable Cataloging. ICP 2009 was reflected in cataloging rules such as RDA and ISBD 2010 as the minimal principles for uniformity in establishing each nation's cataloging rules. In contrary, KCR4 needs to be revised because it has never been changed after 2003, and has only description rules without any rules for the choice and forms of access points. Therefore, this study aims to grasp requirements that should be reflected in KCR4 through analyzing ICP 2009. In first step, it is to grasp the features of ICP 2009 by comparing PaRIS Principle and ICP 2009 and to compare KCR4 in aspects of ICP 2009. The detailed elements for comparison between ICP 2009 and KCR4 are scope, general principles, entitles, attributes, and relationships, objectives and functions of the catalogue, bibliographic description, access points, foundations for search capabilities as the contents of ICP 2009. As a result, this study could give some directions of KCR4 in the future. First, ISBD 2010 and conceptual models should be reflected in KCR4 in description. Second, it should regulate the authority access points in KCR4 based on ICP 2009. Third, it will describe essential access points of work and expression attributes in bibliographic records and authority records to find works and expression. This study will contribute to guide the national cataloging rules.

• Proceedings of the Korean Vacuum Society Conference
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• 2009.02a
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• pp.229.1-229.1
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• 2009