• 제목/요약/키워드: A first principles study

검색결과 825건 처리시간 0.039초

제일원리 전산모사를 통한 리튬 이온 전지의 LiMn2O4 전극-전해질 계면 반응 분석 (First-principles Study on the Formation of Solid-Electrolyte Interphase on the LiMn2O4 Cathode in Li-Ion Batteries)

  • 최대현;강준희;한병찬
    • 한국표면공학회:학술대회논문집
    • /
    • 한국표면공학회 2016년도 추계학술대회 논문집
    • /
    • pp.97-97
    • /
    • 2016
  • Development of advanced Li-ion battery cells with high durability is critical for safe operation, especially in applications to electric vehicles and portable electronic devices. Understanding fundamental mechanism on the formation of a solid-electrolyte interphase (SEI) layer, which plays a substantial role in the electrochemical stability of the Li-ion battery, in a cathode was rarely reported unlike in an anode. Using first-principles density functional theory (DFT) calculations and ab-initio molecular dynamic (AIMD) simulations we demonstrate atomic-level process on the generation of the SEI layer at the interface of a carbonate-based electrolyte and a spinel $LiMn_2O_4$ cathode. To accomplish the object we calculate the energy band alignment between the work function of the cathode and frontier orbitals of the electrolyte. We figure out that a proton abstraction from the carbonate-based electrolyte is a critical step for the initiation of an SEI layer formation. Our results can provide a design concept for stable Li-ion batteries by optimizing electrolytes to form proper SEI layers.

  • PDF

미술의 요소와 원리에 근거한 만 2세 표준보육과정 교사용 지도서 미술활동 분석 (An Analysis of the Fine Arts Activities on the Standard Childcare Curriculum Guidebook(for 2 years) for Teachers Based on the Elements and Principle of Fine Arts)

  • 김순희;이순복
    • 한국보육지원학회지
    • /
    • 제14권4호
    • /
    • pp.63-83
    • /
    • 2018
  • Objective: The purpose of this study was to analyze how the elements and principles of fine arts were reflected in art related activities in the teacher's manual on standard childcare curriculum for a period of 2 years. Methods: The analysis criteria for the elements of fine arts were modified and complemented based on Kim and Gang(2011) and the same was done for the principles of fine arts based on Lee et al(2015). Results: First, as a result of analyzing the art contents according to life theme in art related activities, 'artistic expression' appeared the most in all nine life themes. Second, as a result of analyzing the art related contents in the standard childcare curriculum for 2 years based on the elements of fine arts, plane, texture, shape, color, volume, line, spot, space, composition, light and shade appeared in order. Third, as a result of analyzing the art related contents on the principles of fine arts, movement, emphasis, variety, unity, rhythm, proportion, balance and pattern appeared in order. Conclusion/Implications: The results of this research suggest that the childcare activities have to be devoloped in order to provide the balanced experiences with fine arts activities.

자기주도학습강화를 위한 통합교육 발달장애학생 대상 모바일컨텐츠 설계 방안 연구 (A Study on Mobile Contents Design Plan of Developmental Disabled Students with Integrated Education for Reinforcing Self-directed Study)

  • 이금지;전우천
    • 한국정보교육학회:학술대회논문집
    • /
    • 한국정보교육학회 2010년도 하계학술대회
    • /
    • pp.251-257
    • /
    • 2010
  • 장애학생의 통합은 다른 학생들과 같은 장소에 함께 있는 것에서 시작하지만 수업에 의미있게 참여하여 질적인 통합에 접근할 수 있도록 한다. 본 연구는 이를 위하여 모바일러닝 (Mobile Learning) 컨텐츠 개발을 통해 통합장면의 장애학생이 일반 교과수업에 좀 더 접근하여 능동적으로 참여할 수 있도록 하는데 연구의 목적이 있다. 본 연구에서는 첫째 모바일러닝의 개념과 장점을 제시하고 둘째, 발달장애 학생을 위한 컨텐츠 설계하여 사회과 교과의 특성과 교육과정 수정, 모바일러닝 학습체제 구성 등 모바일러닝 컨텐츠 개발과 적용에 필요성을 중심으로 논의를 전개하였다

  • PDF

장산뢰(張山雷)의 중풍(中風) 치료법(治療法)에 관한 연구(硏究) - 『중풍각전(中風斠詮)』을 중심으로 - (A Study on the Zhongfeng Treatment of Zhang Shanlei Based on the Zhongfeng Jiaoquan)

  • 李相協
    • 대한한의학원전학회지
    • /
    • 제36권4호
    • /
    • pp.93-108
    • /
    • 2023
  • Objectives : This paper aims to study the characteristics of zhongfeng treatment by examining the eight principles of zhongfeng treatment in the Zhongfeng Jiaoquan of Zhang Shanlei along with Zhang Bolong's treatment of 'Yangxu Leizhongfeng[Yang deficiency pseudo Wind damage]' which is missing from the eight principles. Methods : The treatment methods in the Zhongfeng Jiaoquan was organized in the order of cause, characteristic, symptom, treatment, and precautions, in order to analyze features that were emphasized by Zhang in zhongfeng treatment. Results : First, treatment for bizheng is to 'open and close', then apply methods of 'qianyang jiangqi(潛陽降氣)' and 'zhenni huatan(鎭逆化痰)' while that for tuozheng is to 'lianyin yiye(戀陰益液)' accompanied by medicinals that 'qianzhen xutang(潛鎭虛陽)'. Second, treatment for ganyang shangnizheng is to 'qianzhen rougan', while for tanzian yongsezheng, one must 'dangdi(蕩滌)' for those who are strong in qi, 'xiehua(泄化)' for those who are weak in qi, while for those who have qinizheng[qi reverse syndrome] to 'shunqi(順氣).' Third, for deficiency in xinye and ganyin, one must 'yuyin yangxue[育陰養血]', while for deficiency in shenyin, one must first 'qianjiang shena[潛降攝納]' then slowly apply the method of 'ziyang shenyin[滋養腎陰]' if there is no phlegm turbidity. Fourth, in order to communicate the meridians and unfold collaterals, if the pathogen is external, apply the method of 'yangxue tongluo[養血通絡]', while if the pathogen is internal, calm by doing 'qianyang zhenni[潛陽鎭逆].' Fifth, in order to treat pseudo zhongfeng caused by yang deficiency, one must 'lianyin gutuo[戀陰固脫]' while using medicinals that 'jiangxiang[潛降]'. Conclusions : Treatment of zhongfeng in the Zhongfeng Jiaoquan diverged from 'wenjing sanhan', the usual approach to zhongfeng which sees it as external, and established the 'qianjiang zhenshe [潛降鎭攝]' treatment method based on the internal wind theory. It suggests a new Korean Medical pathology based on theories of Western medicine, and introduces eight principles in treating zhongfeng, which would influence the treatment of zhongfeng in the future.

Si(001)에 흡착되는 NO에 대한 제일원리 분자동역학 연구 (First-principles molecular dynamics study of NO adsorption on Si(001))

  • 정석민
    • 한국진공학회지
    • /
    • 제14권2호
    • /
    • pp.97-102
    • /
    • 2005
  • 제일원리 분자동역학 방법을 이용하여 Si(001) 표면에 NO 분자 흡착을 연구하였다. NO 분자가 Si(001)의 dimer축과 나란히 흡착될 경우에 50K에서도 분해가 일어났다. 이를 에너지 장벽으로 환산해 보면 0.006eV로서 거의 무시해도 좋을 정도이다 만일 NO 분자가 표면에 수직으로 들어오면 이웃에 있는 dimer에 걸쳐서 분해가 일어났다. 이 경우는 에너지 장벽은 0.08eV 정도였으며 여전히 낮은 수준이다. 분해가 된 산소분자는 dimer와 기판 사이의 backbend로 파고들어서 (에너지 장벽 0.007eV) 안정된 구조를 만들었다. 또 dimer에 나란히 흡착된 분자 상태의 경우는 N=Si_3$를 만들기도 하는데 속전자준위분광학(core level spectroscopy) 실험 결과와 일치한다.

전기화학적 암모니아 합성을 위한 루테늄 촉매 표면에서의 질소 환원반응 메커니즘 해석의 위한 제1원리 모델링 (First-Principles Analysis of Nitrogen Reduction Reactions on Ruthenium Catalyst Surfaces for Electrochemical Ammonia Synthesis)

  • 조미현;이상헌
    • Korean Chemical Engineering Research
    • /
    • 제61권4호
    • /
    • pp.598-603
    • /
    • 2023
  • 촉매를 사용한 전기화학적 암모니아 생산은 주변 온도 및 압력 조건, 환경 친화적인 작동 및 고순도 암모니아 생산을 가능하게 함으로써 전통적인 하버-보쉬 방법을 대체할 대안으로서 가능성이 있다. 본 연구에서는 제1원리 계산을 사용하여 루테늄 촉매의 표면에서 발생하는 질소 환원 반응에 초점을 맞춘다. 루테늄의 (0001) 및 (1000) 표면에서 질소 환원에 대한 반응 경로를 모델링하여 반응 구조를 최적화하고 각 단계에 대한 유리한 경로를 예측했다. 각 표면에서의 N2의 흡착 구성은 후속 반응 활동에 상당한 영향을 미쳤으며, 깁스자유에너지 분석은 가장 유리한 질소 환원 구성을 도출하였다. 루테늄의 (0001) 표면에서는 질소 분자가 표면에 수직으로 흡착하는 end-on 형태가 가장 유리한 N2 흡착에너지가 나타났으며 유사하게, (1000) 표면에서도 end-on 형태가 안정적인 흡착 에너지 값을 보였다. 이어서, distal 및 alternating 구성 모두에서 최적화된 수소 흡착을 통해 NH3의 최종 탈착까지 이론적으로 완전한 반응 경로를 설명했다.

First-principles Study on the Half-metallicity and Magnetism of a Full Heusler Alloy, Co2HfSi, in Bulk State and at its (001) Surfaces

  • Jin, Ying-Jiu;Lee, Jae-Il
    • Journal of Magnetics
    • /
    • 제13권4호
    • /
    • pp.115-119
    • /
    • 2008
  • The authors predicted that $Co_2HfSi$, a $Co_2$-based full Heusler alloy, is being a half-metallic ferromagnet by first-principles calculations using the all electron full-potential linearized augmented plane wave method which adopts the generalized gradient approximation. The integer value of the calculated total magnetic moment of 2.00 ${\mu}_B$ per formula unit and a spin gap of 0.69 eV in spin down state confirmed the half-metallicity of bulk $Co_2HfSi$. For the $Co_2HfSi$(001) surface, we considered two possible surface terminations, namely, Co terminated and HfSi terminated surfaces. It was found that half-metallicity was retained at the HfSi-terminated surface but not at the Co-terminated surface. The magnetic moment of surface Co atoms in the Co-terminated surface was slightly lower than that of Co atoms in deep inner-layers, whereas the magnetic moments of Hf and Si atoms at the HfSi-terminated surface were almost same as those in deep inner-layers.

BaZrO3의 부피 변화가 프로톤 전도 에너지 장벽에 미치는 영향 (Effect of Volume Variation on Energy Barrier for Proton Conduction in BaZrO3)

  • 정용찬;김대희;김병국;김영철
    • 한국세라믹학회지
    • /
    • 제47권5호
    • /
    • pp.474-478
    • /
    • 2010
  • We studied the energy barrier for proton conduction with volume variation in $BaZrO_3$ using a first principles study to investigate an optimum volume for the proton conduction. The volume increase of $BaZrO_3$ was expected to decrease the energy barrier for proton rotation and to increase that for proton transfer, and these trends could be extrapolated when the volume was decreased. However, the energy barriers for the proton transfer with the volume decrease were increased, while all the other energy barriers varied as expected. We could explain this unexpected behavior by the bent Zr-O-Zr structure, when the volume was decreased.

제일원리 계산을 통한 유해화학물질 PCl3와 POCl3의 물분자 촉진 수화반응 연구 (First Principles Study on Hydrolysis of Hazardous Chemicals PCl3 and POCl3 Catalyzed by Water Molecules)

  • 정현욱;강준희;전호제;한병찬
    • 한국표면공학회:학술대회논문집
    • /
    • 한국표면공학회 2017년도 춘계학술대회 논문집
    • /
    • pp.126-126
    • /
    • 2017
  • Using first principles calculations we unveil fundamental mechanism of hydrolysis reactions of two hazardous chemicals $PCl_3$ and $POCl_3$ with molecular water clusters nearby. It is found that the water molecules play a key role as a catalyst significantly lowing the activation barriers by transferring its protons to the reaction intermediates. Interestingly, torsional angles of molecular complexes at transition states are identified as a vital descriptor on the reaction rate. Analysis of charge distribution over the complexes further reinforces the finding with atomic level correlation between the torsional angle and variation of the orbital hybridization state of P in the complex. Electronic charge separation (or polarization) enhances thermodynamic stability of the activated complex at transition state and reduces the activation energy through hydrogen bonding network with water molecules nearby. Calculated potential energy surfaces (PES) for the hydrolysis reactions of $PCl_3$ and $POCl_3$ depict their two contrastingly different profiles of double- and triple-deep wells, respectively. It is ascribed to the unique double-bonding O=P in the $POCl_3$. Our results on the activation free energy show well agreements with previous experimental data within $7kcalmol^{-1}$ deviation.

  • PDF

A First-principles Study on Magnetic and Electronic Properties of Ni Impurity in bcc Fe

  • Rahman, Gul;Kim, In-Gee
    • Journal of Magnetics
    • /
    • 제13권4호
    • /
    • pp.124-127
    • /
    • 2008
  • The magnetic and electronic properties of Ni impurity in bcc Fe ($Ni_1Fe_{26}$) are investigated using the full potential linearized augmented plane wave (FLAPW) method based the generalized gradient approximation (GGA). We found that the Ni impurity in bcc Fe increases both the lattice constant and the magnetic moment of bcc Fe. The calculated equilibrium lattice constant of $Ni_1Fe_{26}$ in the ferromagnetic state was 2.84 A, which is slightly larger than that of bcc Fe (2.83 ${\AA}$). The averaged magnetic moment per atom of $Ni_1Fe_{26}$ unit cell was calculated to be $2.24{\mu}_B$, which is greater than that of bcc Fe (2.17 ${\mu}_B$). The enhancement of magnetic moment of $Ni_1Fe_{26}$ is mainly contributed by the nearest neighbor Fe atom of Ni, i.e., Fe1, and this can be explained by the spin flip of Fe1 d states. The density of states shows that Ni impurity forms a virtual bound state (VBS), which is contributed by Ni $e_{g{\downarrow}}$ states. We suggest that the VBS caused by the Ni impurity is responsible for the spin flip of Fe1 d states.