• Title/Summary/Keyword: first-principles calculation

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

  • Choi, Kyung-Sook;Anderson, Gwen;Jun, Myung-Hee
    • The Journal of Korean Academic Society of Nursing Education
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    • v.12 no.1
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    • pp.104-114
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    • 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.

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

  • Yook, Young-Jin;Chung, Yong-Chae;Lee, Young-Jin;Im, Jong-In
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.201-201
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    • 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.

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

  • Tran, Van Quang;Kim, Miyoung
    • Journal of the Korean Magnetics Society
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    • v.23 no.1
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    • pp.1-6
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    • 2013
  • Spin-orbit coupling (SOC) effect is known to be the physical origin for various exotic magnetic phenomena in the low-dimensional systems. Recently, SOC also draws lots of attention in the study on magnetically doped thermoelectric alloys to determine their properties as the thermoelectric application as well as the topological insulator via the exact electronic structures determination near the Fermi level. In this research, aiming to investigate the spin-orbit coupling effect on the structural properties such as the lattice constants and the bulk modulus of the most widely investigated thermoelectric host material, $Bi_2Te_3$, we carried out the first-principles electronic structure calculation using the all-electron FLAPW (full-potential linearized augmented plane-wave) method. Employing both the local density approximation (LDA) and the generalized gradient approximation (GGA), the structural optimization is achieved by varying the in-plane lattice constant fixing the perpendicular lattice constant and vice versa, to find that the SOC effect increases the equilibrium lattices slightly in both directions while it markedly reduces the bulk modulus value implying the strong orientational dependence, which are attributed to the material's intrinsic structural anisotropy.

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

  • Hong, Soon Cheol
    • Journal of the Korean Magnetics Society
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    • v.26 no.1
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    • pp.1-6
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    • 2016
  • Pd has the highest magnetic susceptibility among single element metals and often shows ferromagnetism under some special environments. In this paper, we report magnetism of 5- and 9-monolayers (ML) calculated by using full-potential linearized augmented plane wave method. Exchange-correlation interaction is taken into account in local density approximation (LDA) and generalized gradient approximation (GGA) and calculational results in LDA and GGA are compared with each other. It is found that calculations by LDA are more reliable compared to those by GGA because LDA prediction of paramagnetism of bulk Pd is consistent with experiments, whereas GGA predicts wrongly ferromagnetim of bulk Pd. Calculational results in LDA on a 5-ML Pd(111) thin film shows a ferromagnetic ground state unlike a paramagnetic ground state of bulk Pd. The center Pd layer of the 5-ML Pd(111) thin film has the largest magnetic moment ($0.273{\mu}_B$) among the layers and |m| = 1 orbital states play a dominant role in stabilizing the ferromagnetism of the 5-ML Pd(111) thin film. A 9-ML Pd(111) thin film in a ferromagnetic state has almost the same total energy as in a paramagnetic state. Since the magnetization of the 9-ML Pd(111) thin film is stable, the ferromagnetic state may be meta-stable.

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

  • Hong, Ji-Hyeon;Seo, Dong-Hwa;Kim, Seong-Uk;Gwon, Hyeok-Jo;Park, Yeong-Uk;Gang, Gi-Seok
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2010.05a
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    • pp.37.2-37.2
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    • 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.

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A Study on the Establishment of Basic Design Concept for Semi-Submersibles (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))

  • J.E.,Park;Z.G.,Kim;J.H.,Hwang;S.J.,Yim;H.S.,Choi
    • Bulletin of the Society of Naval Architects of Korea
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    • v.20 no.2
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    • pp.1-20
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    • 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.

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

  • Choi-Koh, Sang-Sook;Choi, Kyung-Hwa
    • The Mathematical Education
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    • v.45 no.4 s.115
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    • pp.439-457
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    • 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.

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

  • Jang, Y.R.;Park, Jin-Woo;Yu, B.D.
    • Journal of the Korean Magnetics Society
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    • v.19 no.2
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    • pp.43-46
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    • 2009
  • The magnetic and structural properties of the (8, 0) BN nanotubes with transition metals (TM) of Fe, Co, or Ni substitution for B or N were investigated using a first-principles calculation. It was found that TM substitution makes the cross section being distorted and the bond length TM-B or TM-N being longer than that of the original B-N one. The magnetic moment is larger for the TM substitution for B than one for N, and it is mainly due to the 3d electrons of TM atoms.

Magnetism and Magnetocrystalline Anisotropy at fcc Fe (001) Surface

  • Yun, Won-Seok;Cha, Gi-Beom;Hong, Soon-Cheol
    • Journal of Magnetics
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    • v.13 no.4
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    • pp.144-148
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    • 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
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    • v.7 no.4
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    • pp.132-137
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    • 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.