• Title/Summary/Keyword: first-principles

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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.

First-Principles Study on the Electronic Structure of Bulk and Single-Layer Boehmite

  • Son, Seungwook;Kim, Dongwook;Na-Phattalung, Sutassana;Ihm, Jisoon
    • Nano
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    • v.13 no.12
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    • pp.1850138.1-1850138.6
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    • 2018
  • Two-dimensional (2D) or layered materials have a great potential for applications in energy storage, catalysis, optoelectronics and gas separation. Fabricating novel 2D or quasi-2D layered materials composed of relatively abundant and inexpensive atomic species is an important issue for practical usage in industry. Here, we suggest the layer-structured AlOOH (Boehmite) as a promising candidate for such applications. Boehmite is a well-known layer-structured material and a single-layer can be exfoliated from the bulk boehmite by breaking the interlayer hydrogen bonding. We study atomic and electronic band structures of both bulk and single-layer boehmite, and also obtain the single-layer exfoliation energy using first-principles calculations.

First-Principles Study on Thermodynamic Stability of UO2 with He Gas Incorporation via Alpha-Decay

  • Kwon, Choa;Lee, Kwanpyung;Han, Byungchan
    • Korean Chemical Engineering Research
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    • v.57 no.3
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    • pp.368-371
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    • 2019
  • Using first principles calculations we investigated the thermomechanical stability of spent nuclear fuels (SNF), especially how mechanical properties of $UO_2$, such as, bulk, shear and Young's moduli and Poisson's ratio vary through alpha-decay of U into Th with generation of He gas. Our results indicate that substitution of U by Th through alpha decay ($U_{1-x}Th_xO_2$) does not significantly affect the stability of the grain in a fuel matrix. In addition, we studied the transport properties of He in and boundaries of the $U_{1-x}Th_xO_2$ grain. Helium preferentially resides at the grain boundaries through diffusion. Our study can contribute to substantial reduction of environmentally risk and enhancement of our sustainability by safe control of radioactive materials.

Principles and Guidelines for Social Impact Assessment: A Critical Review on the US Case (사회영향평가의 원칙 및 지침에 관한 연구 - 미국 사례를 중심으로 -)

  • Jung, Juchul;Lim, Jaeyoung
    • Journal of Environmental Impact Assessment
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    • v.16 no.1
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    • pp.45-58
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    • 2007
  • Despite the ubiquitous practice of environmental impact assessment around the world, social impact assessment has been alienated from assessment process from the beginning. Not until 1993 was 'Interorganizational Committee' established in the United States to prepare for 'Principles and Guidelines for Social Impact Assessment.' This study is an attempt to critically examine US 'Principles and Guidelines.' First, the study traces history of social impact assessment to reveal why the latter became "the orphan in the assessment process." Second, it critically reviews 'Principles and Guidelines' to find its merits and defects. For instance, a principle regarding environmental justice is perceived as necessary as society has become conscious of social justice and equity while putting too much emphasis on predictive traits of social impact assessments only fosters "checklist mentality." Third, the study reflects on 'Principles and Guidelines' in particular and social impact assessment in general in order to probe what is social impact assessment. To do so, it pays attention to scholars, who have criticized technocratic and procedural elements of 'Principles and Guidelines.' They show that social impact assessment is philosophically and methodologically teleological in that "fluid and contested meanings" between social impacts and the public are meaningful in itself. And simple procedural guarantee of the public involvement, they argue, is not enough to define social impacts. Lastly, from the critical analysis of 'Principles and Guideline,' the study looks for alternatives to improve how to assess social impacts in a Korean context.

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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Deciding for Other as Christian Bioethics (대리인의 사전의료지시서와 기독교 생명윤리)

  • O, Seung-Hun
    • Korean Journal of Hospice Care
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    • v.7 no.2
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    • pp.26-41
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    • 2007
  • There are three things that are not known to the human being. That is when, where and how one will die. Most people live ignoring death. However, elements of death linger everywhere. The purpose of this treatise is investigates about justification Deciding for Other directions. First, I will investigate about Deciding for Other directions, when patient can not decide own, I will do investigate agent's decision's problem. Second, These four principles provide the common ground for biomedical ethics. Principlism argue that a method using four principles can resolve controversies in bioethics. The method holds that there are four principles-respect for autonomy, nonamleficence, beneficence, justice- that articulate the necessary conditions of common morality for health care and bioethics. Beauchamp and Childress respond by arguing that the two problems are nc the meaning or interpretation but the process of specification. Third, So, Supplement four principles' problem to Levinas concept of the Other theory. Levinas concept of the Other is very resemblant with 'Love your neighbour as yourself." Christians believe that Love is above all and they act accordingly. They base this faith mainly upon the motto of "love your neighbour as yourself." Fourth. difficult part of Levinas concept of the Other is that there is no human to equal infinite sense of responsibility. Can be supplemented about this through cooperation of community. Four principles can be brought to bear on moral choices. And they asserts that each principles has weigh but they do not assign a priority weighting of ranking. All the principles are equal in moral decision making.

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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.

The Applicability of he UNIDROIT Principles in Interactional Commercial Arbitration (국제상사중재(國際商事仲裁)에서 UNIDROIT 원칙(原則)의 적용가능성(適用可能性))

  • Oh, Won Suk
    • Journal of Arbitration Studies
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    • v.9 no.1
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    • pp.161-182
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    • 1999
  • The purpose of this paper is to examine the applicability of the UNIDROIT Principle in international commercial arbitration. For this purpose, I have studies the basic two characters of this Principles: One is of general rule(principle); Another is of international and commercial character. According to CISG, questions concerning matters governed by the CISG which are not expressly settled in it are to be settled in conformity with the general principles, so this Principles will cover many questions which are not expressly settled in the applicable law, by gap-filing, analogy or usage. In the preamble of this Principles, there are five cases in which the Principles shall be applied or may be applied. If the disputes are submitted to the any national court, the application of this Principles would be restricted because of the mandatory rules of national, international or supranational origin. But the disputes are submitted to arbitration, the arbitrator would have more discretional powers to apply the Principles than the judge. The reason is that in the arbitration, the arbitrators do not bear obligation to act in conformity with the law applicable by virtue of the rules of rules of private international law. I also examined the applicability of the Principles in cases which there are no mentions in preamble: When the international arbitrators choose the Principles; When the arbitrators decide ex aequo et bono; When the both parties have not chosen the governing law; When there are gaps in domestic law chosen by the parties; When the applicable domestic law is insufficient. In all these cases, the Principles may be applied more easily and conveniently in arbitration than in litigation. Thus to envisage the application of this Principle in international arbitration, first both parties in international commercial contracts should incorporate this Principle as a governing law in their contracts, and second, the arbitrators should try to apply this Principles in their arbitrations by choice, analogy, general principles or usage.

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ON TECHNICAL POSSIBILITY AND PRACTICAL EXPERIENCE OF ULTRASONIC SCALE PREVENTING DEVICES USE ON BOILERS AND HEAT-EXCHANGERS IN RUSSIA

  • Semenov, A.G.
    • Proceedings of the Acoustical Society of Korea Conference
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    • 1994.06a
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    • pp.728-733
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    • 1994
  • Scientific foundation for ultrasonic scale preventing devices construction was given in 40S-50S of this century but their production in former USSR was organized later in 70th. Several different principles of scale preventing is overviewed together with physical principles of ultrasonic method. Practical experience received in USSR in 80S is discussed. Technical decisions and inventions used for construction of the first device UZU-1 produced in Cheboksary plant are enumerated and principles of UZU-2 device are briefly sketched.

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Interaction of DEMS with H-terminated Si (001) Surface: A First Principles Study (DEMS와 H-terminated Si (001) 표면의 상호작용: 제일원리연구)

  • Kim, Dae-Hyun;Kim, Dae-Hee;Park, So-Yeon;Seo, Hwa-Il;Lee, Do-Hyoung;Kim, Yeong-Cheol
    • Journal of the Korean Ceramic Society
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    • v.46 no.4
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    • pp.425-428
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    • 2009
  • We performed a density functional theory study to investigate the interaction of DEMS (diethoxymethylsilane) with the H-terminated Si (001) surface. The optimum structure of DEMS was first calculated by a first principles study. The dissociation probability of the O-C bond of DEMS was higher than the other seven bonds based on the bond energy calculation. When the fragmented DEMS groups reacted with the H-terminated Si (001) surface, it was the most favorable among the eight reactions to form a bond between the Si atom on the surface and the O atom of a fragmented DEMS group (($C_2H_5O$)Si($CH_3$)(H)-O-) by forming a $C_2H_6$ as by-product.