• Title/Summary/Keyword: A first principles study

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A First-principles Study on Magnetism of Al Impurity in bcc Fe

  • Rahman, Gul;Kim, In-Gee
    • Journal of Magnetics
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    • v.16 no.1
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    • pp.1-5
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    • 2011
  • The magnetism and electronic structure of bcc $Al_1Fe_{26}$ was investigated by means of first-principles calculations with and without spin-orbit coupling (SOC). From the calculated total energy, the SOC corrected system is shown to be approximately 5 meV per atom lower than the SOC uncorrected system. The induced spin magnetic moment at the Al site was -0.125 ${\mu}_B$ without SOC and -0.124 ${\mu}_B$ with SOC. The orbital magnetic moments were calculated to be 0.002 ${\mu}_B$ in [$\overline{1}$00] direction for Al. The electronic structures showed the nearest neighbor antiferromagnetic interaction between Fe and Al to be essential for determining the magnetism of the $Al_1Fe_{26}$ system.

A Study on Principles of the Law of Software Contracts Drafts in America (미국 소프트웨어 계약법 원칙 초안에 대한 소고)

  • Cho, Hyun-Sook
    • International Commerce and Information Review
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    • v.11 no.1
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    • pp.333-351
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    • 2009
  • The American Law Institute(ALI) has presented drafts of "Principles of the law of software contracts" to clarify and unify the law of software transactions. These principles apply to agreements for the transfer of or access to software. Providing these principles means something in software contracts. First of all, these principles seek to limit the scope to cover only contracts involving software exchanged or accessed for consideration, while UCITA includes a wide variety of "computer information". Secondly, this project is "Principles" instead of "Restatement" which means that these principles are not the law unless a court adopts it. This is for flexibility not to hinder law's adoptability of new legal issues that might be created in the future since the software industry has developed. Third, the project seek to balance between software transferor's interest and transferees to permit the use of remote disablement in limited circumstances. These principles, however, should be considered some concerns in the future work. For example, not to be a unconscionable agreement, it is better to suggest the specific click-wrap procedure and be more illustrative about what types of browser-wrap language are acceptable and what types are not.

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Developing and Applying Design Principles for Maker Programs Using Virtual Reality : Focusing on the Development of Simulation Application (가상현실 기반 메이커 교육 프로그램 설계원리 개발 및 적용 : 시뮬레이션 앱 구현을 중심으로)

  • Park, Taejung
    • Journal of Information Technology Services
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    • v.19 no.6
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    • pp.161-175
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    • 2020
  • The current study aimed to develop the design principles for maker programs using virtual reality and apply them in developing a simulation mobile application. First, through collecting and analyzing the relevant studies and cases eight design principles with four components were derived. Then, these initial design components and principles were revised and improved in accordance with evaluations of an expert panel composed of three professors/researchers, two teachers, and two IT industrial experts. Based on the revised design principles, a VR simulation app for maker education was developed and evaluated on whether the principles were properly applied to the app development by the expert panel. The finalized eight design principles, as a research outcome, can contribute to the design and development of various types of educational programs that can replace the actual making experience even in educational fields where it is difficult to build maker spaces or provide materials and equipment. In the near future, empirical studies are expected to develop customized maker programs considering the characteristics, levels, and needs of students and verify their educational effectiveness.

A Study on eTextbook Development for Mobile Learning in a University (대학에서의 모바일 러닝을 위한 전자교재 개발 사례 연구)

  • Jung, Hyojung;Chon, Eunhwa;Suh, Eung-Kyo
    • Journal of Information Technology Services
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    • v.14 no.4
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    • pp.237-256
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    • 2015
  • The purpose of this study is to develop the eTextbook and to explore the usability of the eTextbook for accelerating mobile learning in university. This study was primarily based on needs analysis of students, and eTextbook was created based on digital publishing through Adobe DPS. The major design principles of the eTextbook based on previous studies were as follow. First, eTextbook should deliver learning contents in a simple and systematic way. Second, eTextbook should induce student's flows by providing segmented learning contents and various learning resources. Third, eTextbook should expand information accessibility by providing a wide variety of multimedia functions. The development principles of eTextbook have been developed based on cognitive psychology. Location and function of the link or icon used for eTextbook have been developed on the basis of the principles of cognitive psychology. The main development principles were Coherence, Signaling, Redundancy, Segmentation, Multimedia principle, and so on. In order to examine usability of the developed eTextbook, experts' and learners' reactions were evaluated. The primary responses of learners are that the eTextbook increased the learning accessibility and provided various multimedia factors, and thus increased the learning flows in the class.

A First Principles Study of Mn on AlGaP2 Semiconductor Surface (AlGaP2 반도체내와 표면의 Mn에 대한 제일원리 해석)

  • Kang, Byung Sub
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.1
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    • pp.12-17
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    • 2021
  • The electronic and magnetic properties for Mn-adsorbed on the chalcopyrite (CH) AlGaP2 semiconductor are investigated by using first-principles FPLMTO method. The clean CH-AlGaP2 without adsorbed Mn is a p-type semiconductor with a direct band-gap. The Mn-adsorbed CH-AlGaP2 exhibits the ferromagnetic state. It is more energetically stable than the other magnetic ones. The interstitial site on P-terminated surface is more energetically favorable one than the Al/Ga-terminated surface, or the other adsorbing sites. In the case of Mn-adsorbed Al/Ga-terminated surface, it is induced a strong coupling between Mn-3d and neighboring P-3p electrons. The holes of partially unoccupied minority Mn-3d state and majority (or minority) Al-3p or P-3p state are induced. Thus a high magnetic moment of Mn is sustained by holes-mediated double-exchange coupling. It is noticeable that the semiconducting and half-metallic characteristics of CH-AlGaP2:Mn thin film is disappeared.