• 제목/요약/키워드: first-principles calculation

검색결과 86건 처리시간 0.028초

국내 종양유전상담 간호사를 위한 단기 교육프로그램 개발 (The First Korean Cancer Genetic Counseling Program for Nurses)

  • 최경숙;구웬앤더슨;전명희
    • 한국간호교육학회지
    • /
    • 제12권1호
    • /
    • pp.104-114
    • /
    • 2006
  • Genetic knowledge for oncology nurses is important in Korea because oncologists are incorporating genetic counseling and genetic testing into their practice. The purpose of this paper is to describe our method of developing the first academic cancer genetic risk assessment and counseling course for Korean nurses. A one-week (non-credit) cancer genetics counseling program was constructed for master's level Korean oncology nurses. The course emphasized basic genetic concepts and principles the genetics of cancer; hereditary cancer syndromes; family history assessments; pedigree construction; risk calculation; surveillance recommendations and treatment options ethical, legal, social, and psychological issues inherent in genetic testing. The goals of this program are to: 1) provide a comprehensive knowledge base for nurses who are currently expanding their scope of practice into the genetic counseling role 2) introduce this knowledge to nurses who want to use it in their practice; and 3) provide cancer genetic knowledge and resources to Korean nursing faculty who plan to incorporate this knowledge into existing master's courses. This academically-based course is recognized as valuable by nurses, nursing faculty, and physicians. With this new knowledge nurses can begin toexpand their role in delivering comprehensive cancer care services.

  • PDF

제일원리 계산을 이용한 스트론튬 페라이트의 자기적 특성 전산모사 (First-principles study of the magnetic properties of the strontium hexaferrite $SrFe_{12}O_{19}$)

  • 육영진;정용재;이영진;임종인
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
    • /
    • pp.201-201
    • /
    • 2006
  • 영구자석은 크게 Hard ferrite와 희토류계 자석, 그리고 Alnico 주조자석으로 구별되어진다. 그동안 Hard ferrite는 산업적으로 전자기 응용제품 또는 각종 구동 모터에 응용되어 왔지만, 최근 Nd계 희토류 자것이 고성능 모터의 소재로 급격히 대체되고 있다. 하지만, 희토류계 원료에 비해 동일 중량 대비 40~60배 가량 저렴한 Hard ferrite의 사용은 현재까지도 꾸준히 유지되고 있으며, 최근 자동차 고성능 모터용 Sr ferrite의 개발이 연구 중이다.[2] 본 연구에서는 제일원리 전산모사를 통하여 HCP 구조의 기본 Unit Cell 64개 원자를 가진 Sr-ferrite의 격자상수를 계산하여 기존 연구결과와 비교하였으며, 자화에너지와 자기모멘트를 계산하였다. 또한 향후 각종 첨가물의 영향에 대한 연구를 위해 기본 구조 및 치환 구조에 대해 고찰하였다. 그 결과 가장 안정한 에너지를 갖는 격자상수는 a=5.88, b=23.03으로 계산되어 Kimura et al의 측정 결과와 유사한 결과를 얻을 수 있었으며, $E_F$가 3.9171, $M_B$는 46.6481로 계산되었다. 항후 Sr-ferrite의 구조에서 Fe atom의 일부를 동일주기 원소인 Cr, Mn, Co, Ni, Cu로 치환하여 자기적 특성을 계산하여 본 연구결과와 비교하고자 한다.

  • PDF

스핀-궤도 각운동량 상호작용의 구조 최적화에 대한 효과: 비스무스 텔루라이드의 제일원리 계산의 경우 (Spin-orbit Coupling Effect on the Structural Optimization: Bismuth Telluride in First-principles)

  • ;김미영
    • 한국자기학회지
    • /
    • 제23권1호
    • /
    • pp.1-6
    • /
    • 2013
  • 스핀 궤도 각운동량의 상호작용은 저차원계 자성물질에서 나타나는 여러 가지 특이한 현상들의 물리적 원인을 제공하는 것으로 알려져 있다. 최근 들어 자성 도핑을 이용한 열전 물질의 합금에 대한 관심이 높아지면서, 열전 및 위상 절연체(Topological Insulator) 등의 물리적 성질 결정에 중요한 역할을 하는 페르미 에너지 준위 부근에서의 전자구조에 대한 스핀 궤도 각운동량의 효과 연구가 관심을 끌고 있다. 본 연구에서는 가장 일반적인 열전 호스트 물질인 비스무스 텔루라이드의 격자 상수 및 부피 팽창률에 대한 스핀 궤도 각운동량 상호작용의 효과를 연구하기 위하여 모든 전자(all-electron) FLAPW(full-potential linearized augmented plane wave) 방법을 이용하여 전자구조 계산을 수행하였다. 국소밀도 근사법 및 일반 기울기 보정법의 서로 다른 교환상호작용 퍼텐셜을 채용하고, 수평격자 및 수직격자를 분리하여 변화시키는 구조최적화 계산을 통하여, 스핀-궤도 각운동량 상호작용의 효과가 격자상수 평형 값을 약하게 증가시키는 반면, 부피탄성률을 크게 감소시키는 영향을 주며, 그 효과는 구조적 이방성이 뚜렷한 비스무스 텔루라이드의 특성에 의하여 격자방향에 대한 의존성을 보인다는 것을 확인했다.

Pd(111) 박막의 자성: 제일원리계산 (Magnetism of Pd(111) Thin Films: A First-principles Calculation)

  • 홍순철
    • 한국자기학회지
    • /
    • 제26권1호
    • /
    • pp.1-6
    • /
    • 2016
  • Pd은 단일 원소 금속 중에서 자기 감수율이 가장 크고 외부 환경에 따라 강자성 특성을 보이기도 한다. 본 논문은 자성 연구에 가장 적합한 FLAPW 방법을 사용하여 5-ML과 9-ML Pd(111) 박막의 자성을 계산하였다. 전자간 교환-상관 상호작용을 고려하기 위해 LDA와 GGA를 도입하여 두 계산 결과를 비교하였다. LDA 계산은 덩치 Pd이 상자성 상태가 바닥 상태임을 예측하여 실험과 일치하는 반면, GGA 계산은 덩치 Pd이 강자성을 갖는 것으로 잘못 예측하여 Pd 자성에 대해서는 LDA 계산이 더 신뢰할 수 있음을 알았다. 5-ML Pd(111) 박막에 대한 LDA 계산 결과에 의하면 상자성 상태가 바닥인 덩치 Pd과는 다르게 강자성 상태가 더 안정적이었다. 박막의 중앙에 위치한 Pd이 가장 큰 자기모멘트($0.273{\mu}_B$)를 가지며 중앙 Pd 층의 |m| = 1 상태가 덩치의 그것과 큰 차이가 있어 5-ML Pd(111) 박막의 강자성을 유발하는 데 주요 역할을 함을 알 수 있었다. 9-ML Pd(111) 박막은 상자성 상태가 강자성 상태에 비해 안정하였으나 두 상태 사이의 총에너지 차이가 거의 없고 유한한 자기모멘트를 안정적으로 가지는 것으로 계산되어 강자성 상태가 준 안정적임을 보였다.

Structural Evolution of Layered $Li_{1.2}Ni_{0.2}Mn_{0.6}O_2$ upon Electrochemical Cycling in a Li Rechargeable Battery

  • 홍지현;서동화;김성욱;권혁조;박영욱;강기석
    • 한국재료학회:학술대회논문집
    • /
    • 한국재료학회 2010년도 춘계학술발표대회
    • /
    • pp.37.2-37.2
    • /
    • 2010
  • Recently $Li_{1.2}Ni_{0.2}Mn_{0.6}O_2$ has been consistently examined and investigated by scientists because of its high lithium storage capacity, which exceeds beyond the conventional theoretical capacity based on conventional chemical concepts. Consequently, $Li_{1.2}Ni_{0.2}Mn_{0.6}O_2$ is considered as one of the most promising cathode candidates for next generation in Li rechargeable batteries. Yet the mechanism and the origin of the overcapacity have not been clarified. Previously, many authors have demonstrated simultaneous oxygen evolution during the first delithiation. However, it may only explain the high capacity of the first charge process, and not of the subsequent cycles. In this work, we report a clarified interpretation of the structural evolution of $Li_{1.2}Ni_{0.2}Mn_{0.6}O_2$, which is the key element in understanding its anomalously high capacity. We identify how the structural evolution of $Li_{1.2}Ni_{0.2}Mn_{0.6}O_2$ occurs upon the electrochemical cycling through careful study of electrochemical profiles, ex-situ X-ray diffraction (XRD), HR-TEM, Raman spectroscopy, and first principles calculation. Moreover, we successfully separated the structural change at subsequent cycles (mainly cation rearrangement) from the first charge process (mainly oxygen evolution with Li extraction) by intentionally synthesizing sample with large particle size. Consequently, the intermediate states of structural evolution could be well resolved. All observations made through various tools lead to the result that spinel-like cation arrangement and lithium environment are created and embedded in layered framework during repeated electrochemical cycling.

  • PDF

해저자원(海底資源) 개발용(開發用) Semi-Submersible 설계기준(設計基準)의 정립(定立)을 위한 연구(硏究) (A Study on the Establishment of Basic Design Concept for Semi-Submersibles)

  • 박종은;김재근;황종흘;임상전;최항순
    • 대한조선학회지
    • /
    • 제20권2호
    • /
    • pp.1-20
    • /
    • 1983
  • In this paper design criteria for semi-submersibles, effective at the stage of basic design, are reviewed first generally. Thereafter an extensive study is focussed on essential problematic areas such as design load, heaving motion, overall structural analysis and welding technique. The necessity for this kind of research is apparent in the light of the fact that ocean exploration and exploitation becomes extended to deeper ocean and that semi-submersibles are the most favorite unit for operation under this environment. In some sense principles in naval architecture are indeed applicable to the design of semi-submersible. However, because of the difference in geometry between ships and semi-submersibles, there are significant deviations in design method. A thorough discussion is made on particular behaviours of a semi-submersible in stability, wave load, motion characteristics and structural responses. Then some calculation-procedures and design guidelines are tentatively proposed. A numerical calculation for a semi-submersible Sedco 708 is exemplified for better understanding of the concept. The structure has 4 main and another 4 secondary stabilizing columns with catamaran-type lower hull. In this example design condition is supposed to be 28m wave height, 90 knots wind speed for survival condition and seastate 6 for operational condition in water of 100m depth. The numerical result implies that the actual design of this model can be assessed close to optimum. Further intensive research is strongly required in the subject fields of dynamic stability, rational evaluation of wave load statistical basis for fatigue life judgement.

  • PDF

수학사를 활용한 중학교 방정식에서 학생의 수학화 (Student's Mathematization of Equations in the Middle School Using the History of Mathematics)

  • 고상숙;최경화
    • 한국수학교육학회지시리즈A:수학교육
    • /
    • 제45권4호
    • /
    • pp.439-457
    • /
    • 2006
  • This research was to understand the features of mathematization and didactical phenomenology, in a way that was not a routine calculation of equation, rather a complete comprehension by the reinventing historical principles of the equation. To achieve the purpose of this study, one-mate middle school student participated in the study. Interview and observation were used for collecting data during the student's performance. The results of research were: First, the student understood the mathematical concepts from a real life and developed the abstract concepts from it, which were very intimately related with his life. Second, the skill and formula definition were accomplished with the accompanying predicted and consequently derived mathematical concepts. Third, through the approach of using the history of mathematics, he became more interested in what he was doing and took lessons with confidence. Forth, the student performed his learning based on the historical reinventing principle under the proper guidance of a teacher.

  • PDF

전이금속이 치환된 BN 나노튜브의 자성 (Magnetism of BN Nanotubes with Transition Metal Substitution)

  • 장영록;박진우;유병덕
    • 한국자기학회지
    • /
    • 제19권2호
    • /
    • pp.43-46
    • /
    • 2009
  • 지그재그 형태의 (8, 0) BN 나노튜브에서 B 또는 N을 전이금속인 Fe, Co, 또는 Ni로 치환했을 때, 결합길이와 자기모멘트 등 구조적, 자기적 성질을 제일원리계산 방법으로 연구하였다. 전이금속이 치환하게 되면 원래 원 모양이었던 단면의 형태가 찌그러진 타원 모양으로 바뀌게 되며, 결합길이도 원래의 BN 나노튜브에서 B-N의 결합길이보다 길어지는 것으로 계산되었다. 자기모멘트는 B을 치환했을 때가 N을 치환한 경우보다 더 크게 나타났으며, 주로 3d 전자가 자기모멘트 값에 기여한다는 것을 상태밀도 그림으로부터 알 수 있었다.

Magnetism and Magnetocrystalline Anisotropy at fcc Fe (001) Surface

  • Yun, Won-Seok;Cha, Gi-Beom;Hong, Soon-Cheol
    • Journal of Magnetics
    • /
    • 제13권4호
    • /
    • pp.144-148
    • /
    • 2008
  • The size and surface effects on the magnetism of a fcc Fe (001) surface was investigated by performing firstprinciples calculations on 3, 5, 7, and 9 monolayers fcc Fe (001) single slabs with two different two-dimensional lattice constants, ${\alpha}=3.44{\AA}$ (System I) and 3.65 ${\AA}$ (System II), using the all-electron full-potential linearized augmented plane wave method within a generalized gradient approximation. The surface layers were coupled ferromagnetically to the subsurface layer in both systems. However, the magnetism of the inner layers was quite different from each other. While all the inner layers of System II were ferromagnetically coupled in the same way as the surface layer, the inner layers of System I showed a peculiar magnetism, bilayer antiferromagnetism. The calculated spin magnetic moments per Fe atom were approximately 2.7 and 2.9 ${\mu}_B$ at the surface for Systems I and II, respectively, due to the almost occupied Fe d-state being in the majority spin state and band narrowing. The spin orientations of System I were out-of-plane regardless of its thickness, whereas the orientation of System II changed from out-of-plane to in-plane with increasing thickness.

Electronic Structures and Magnetism of the MgCFe3(001) Surface

  • Jin, Ying-Jiu;Kim, I. G.;Lee, J. I.
    • Journal of Magnetics
    • /
    • 제7권4호
    • /
    • pp.132-137
    • /
    • 2002
  • The electronic structures and magnetism of the non-oxide perovskite MgCFe$_3$(001) surface were investigated by using the all-electron full-potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation (GGA). We considered both of the MgFe terminated (MgFe-Term) and the CFe terminated (CFe-Term) surfaces. We found that the minority spin d-bands of Fe(S) of the MgFe-Term are strongly localized and Fermi level (EF) lies just below the sharp peak of the minority spin d-band of Fe(S), while the minority spin d-bands of Fe(S) of the CFe-Term are not localized much and Fermi level (E$_F$) lies in the middle of two peaks of the minority spins. The majority Fe(S) d-band width of MgFe- Term is narrower than that of the CFe-Term. It is found that the magnetic moment of Fe(S) of the MgFe- Term is 2.51 ${\mu}$$_B$, which is much larger than that of 1.97 ${\mu}$$_B$ of the CFe-Term.