• 제목/요약/키워드: first-principles

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제일원리 계산을 활용한 전기화학 촉매 연구 (First-Principles Calculations for Design of Efficient Electrocatalysts)

  • 김동연
    • 한국전기전자재료학회논문지
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    • 제34권6호
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    • pp.393-400
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    • 2021
  • As the recent climate problems are getting worse year after year, the demands for clean energy materials have highly increased in modern society. However, the candidate material classes for clean energy expand rapidly and the outcomes are too complex to be interpreted at laboratory scale (e.g., multicomponent materials). In order to overcome these issues, the first-principles calculations are becoming attractive in the field of material science. The calculations can be performed rapidly using virtual environments without physical limitations in a vast candidate pool, and theory can address the origin of activity through the calculations of electronic structure of materials, even if the structure of material is too complex. Therefore, in terms of the latest trends, we report academic progress related to the first-principles calculations for design of efficient electrocatalysts. The basic background for theory and specific research examples are reported together with the perspective on the design of novel materials using first-principles calculations.

공학교육에서 교수 으뜸원리를 적용한 플립러닝 모델 및 교수 전략에 관한 연구 (Applying First Principles of Instruction to Flipped Classroom in Engineering Education: Model and Instructional Strategies)

  • 임지영;김세영
    • 공학교육연구
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    • 제22권1호
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    • pp.39-47
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    • 2019
  • This study aims to suggest a model and instructional strategies for a flipped classroom using First Principles of Instruction in engineering education in order to organize teaching and learning activities in a flipped classroom. For this purpose, the authors analyzed the literature on the flipped classroom in engineering education and on applying First Principles of Instruction in designing flipped classroom. Then, a framework of flipped classroom employing First Principles of Instruction and instructional strategies were suggested. Two experts examined the validity of the model and of the instructional strategies, and the final version was completed reflecting on those feedback. Since engineering education aims to teach procedural knowledge as well as conceptual knowledge, different instructional strategies upon two types of knowledge were presented. The implication of our work is to illustrate the model and tactics for flipped classroom based on the Merrill's deeply rooted pedagogical approach. This study may contribute to practice in engineering education.

The First-principles View of Nanometal Alloy Catalysts

  • Ham, Hyung Chul;Hwang, Gyeong S.
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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    • pp.129-129
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    • 2013
  • Nanometal alloy catalysts have been found to significantly increase catalytic efficiency, compared to the monometallic counterparts. This enhancement can be attributed to various alloying effects: i) the existence of uniquemixed-metal surface sites [the so called ensemble (geometric) effect]; ii) electronic state changes due to metal-metal interactions [the so called ligand (electronic) effect]; and iii) strain caused by lattice mismatch between the alloy components [the socalled strain effect]. In addition, the presence of low-coordination surface atoms and preferential exposure of specific facets [(111), (100), (110)] in association with the size and shape of nanoparticle catalysts [the so called shape-size-facet effect] can be another important factor for modifying the catalytic activity. However, mechanisms underlying the alloying effect still remain unclear owing to the difficulty of direct characterization. Computational approaches, particularly the prediction using first-principles density functional theory (DFT), can be a powerful and flexible alternative for unraveling the role of alloying effects in catalysis since those can give us quantitative insights into the catalytic systems. In this talk, I will present the underlying principles (such as atomic arrangement, facet, local strain, ligand interaction, and effective atomic coordination number at the surface) that govern catalytic reactions occurring on Pd-based alloys using the first-principles calculations. This work highlights the importance of knowing how to properly tailor the surface reactivity of alloy catalysts for achieving high catalytic performance.

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UNIDROIT Principles 2010에 관한 소고 (A Study on the UNIDROIT Principles 2010)

  • 이시환
    • 무역상무연구
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    • 제51권
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    • pp.101-131
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    • 2011
  • The Governing Council of UNIDROIT at its 90th session adopted on 10 May 2011 the third edition of the Principles of International Commercial Contracts("UNIDROIT Principles 2010"). The UNIDROIT Principles of International Commercial Contracts first published in 1994 and in a second edition in 2004, are taken by legislators worldwide as a model for contract law reform and increasingly used in international contracting and arbitration practice, as well as by the courts to interpret and supplement the applicable domestic law. The UNIDROIT Principles are particularly useful to parties when negotiating and drafting international contracts. The new edition of the Principles, UNIDROIT Principles 2010, prepared by a group of experts from all over the world including representatives of numerous international organizations and arbitration centers. The UNIDROIT Principles 2010 contain new provisions on restitution in case of failed contracts, illegality, conditions, and plurality of obligors and obligees, while with respect to the text of the 2004 edition the only significant changes made relate to the Comments to Article 1.4.

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20세기 건축의 유기적 표현원리에 관한 연구 (A Study on the Organic Expression Principles of the 20C. Architecture.)

  • 김주연;우경덕
    • 한국실내디자인학회논문집
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    • 제18호
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    • pp.51-58
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    • 1999
  • The aim of this study is to discover the organic expression principles of the 20C. Architecture. As a result, first, the organic expression principles was organised in six categories, a. naturalism b. neo-naturalism, c. realism, d. abstractionism, e. regionalism, f. functionalism. Second, among the organic expression principles, the naturalism, the neo-naturalism and the abstractionism were the most dominant organic expression principles of the 20C. Architecture. Third, from 1960, the functionalism have become one of the most dominant organic expression of the 20C. Architecture.

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약사법상 한약제제의 정의 중 한방원리의 의미에 대한 고찰 (Implication of Korean Medicine Principles in Herbal Medicinal Preparations on Pharmaceutical Affairs Act)

  • 임현진;김지훈;조선영;박선동;김윤경
    • 대한한의학방제학회지
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    • 제23권1호
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    • pp.1-14
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    • 2015
  • Objectives : In Pharmaceutical Affairs Act, herbal medicinal preparations are defined as medicines made by Korean medicine principles. But in Act, Korean medicine principles are vague. Thus, there is a request to explain what the Korean medicine principles are. The aim of this study is to suggest implications of Korean medicine principles in definition of herbal medicinal preparations. Methods : With regard for definition of Korean medicine principles, we referred to the domestic and foreign regulations and literature about the history of herbal medicinal preparations. As a result, the meaning of Korean medicine principles was historically examined from various angles. Results : Through this study, we studied the Korean medicine principles from the past medical history. Due to the broad definition of Korean medicinal principles, we tried to extract general ideas of medicine principles first. We also found that we had scientific formulations based on korean medicine principles which could be used in modern society. In the end, we found that numerous medicine principles which include ‘Four qi and five flavors theory’, ‘Processing of medicinals’, ‘Yin and yang theory’, ‘Five phases theory’, ‘Meridian entry of viscera and bowels theory’, ‘Herb Couplet Interaction theory’, ‘Sovereign, minister, assistant and courier theory’, etc. Conclusions : Innumerable principles used from the past existed. These principles were broad and could be used as modern scientific principles. Based on these facts, we illustrated details of Korean medicine principles, hope this principles be widely shared and Korean herbal medicinal preparations be further developed.

First Principles Computational Study of Surface Reactions Toward Design Concepts of High Functional Electrocatalysts for Oxygen Reduction Reaction in a Fuel Cell System

  • Hwang, Jeemin;Noh, Seunghyo;Kang, Joonhee;Han, Byungchan
    • 한국표면공학회지
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    • 제50권1호
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    • pp.1-9
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    • 2017
  • Design of novel materials in renewable energy systems plays a key role in powering transportation vehicles and portable electronics. This review introduces the research work of first principles-based computational design for the materials over the last decade to accomplish the goal with less financial and temporal cost beyond the conventional approach, especially, focusing on electrocatalyst toward a proton exchange membrane fuel cell (PEMFC). It is proposed that the new method combined with experimental validation, can provide fundamental descriptors and mechanical understanding for optimal efficiency control of a whole system. Advancing these methods can even realize a computational platform of the materials genome, which can substantially reduce the time period from discovery to commercialization into markets of new materials.

Effects of Nitrogen Defect on Magnetism of Cu-doped InN: First-principles Calculations

  • Kang, Byung-Sub;Chae, Kwang-Pyo;Lee, Haeng-Ki
    • Journal of Magnetics
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    • 제18권2호
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    • pp.81-85
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    • 2013
  • We investigate the electronic and magnetic properties in Cu-doped InN with the N vacancy ($V_N$) from first principles calculations. There is the long-range ferromagnetic order between two Cu atoms, attributed to the hole-mediated double exchange through the strong p-d interaction between the Cu atom and neighboring N atom. The system of $V_N$ defect in Cu-doped InN has the lowest formation energy. Due to the hybridization between the Cu-3d and $V_N$ states, the spin-polarization on the Cu atoms in the InN lattice is reduced by $V_N$ defect. So, it shows a weak ferromagnetic behavior.