Good cyclability is essential for the potential application of cathode materials. Here, we investigate the structural stability of two-dimensional (2D) Li-layered and three-dimensional (3D) structured polymorphs of Li2FeSiO4 and Li2MnSiO4 using the density functional theory calculation. We find that all 2D Li-layered polymorphs of both materials are unstable upon full-delithiation owing to layer exfolilation, which can lead to an amorphous structure.

Shape-memory alloys (SMAs) are a rare class of metal compound that after a huge mechanical strain can, on heating, recover their original atomic configuration. In the many useful applications of SMAs, the most studied material is NiTi (nitinol). The understanding on the NiTi properties in nano-scale calculations is still lacking. Here, we present a first-principles density functional theory study of the structural energies, mechanical properties, phase-transformation of NiTi.

We have recently demonstrated using classical molecular dynamics that mechanical strain can be an effective tool to combat the intrinsic surface-induced Q-factor degradation in nanowires. The idea underlying this effect is that surface atoms vibrate at different frequencies than do bulk atoms because of their different elastic stiffness. The application of mechanical strain causes the surface atoms to have a stiffness that becomes similar to the bulk atoms, which thus improves the coherency of oscillation, and thus the Q-factors.

Therefore, we have shown that, as opposed to the experiments of Sanchez et al. that the spurious edge modes occur naturally through the MD simulations without application of any non-uniform stresses.? Instead, they arise due to the fact that the carbon atoms at the edges of the graphene sheet have fewer bonding neighbors, and are therefore undercoordinated with respect to the carbon atoms in the interior of the graphene sheet. The lack of bonding neighbors means that the stiffness, and therefore the vibrational frequency of the edge atoms differs from the atoms within the graphene bulk; this difference in vibrational frequency of the edge atoms is illustrated below in Figure (a).

Because this edge induced energy dissipation occurs at 10 K where thermoelastic losses are minimal, we have demonstrated that edge effects are the key intrinsic loss mechanism that causes energy dissipation, and thus low Q-factors in graphene NEMS.

Mainly observed defects in metal film under the external loading are dislocations (line defect). The dislocations in metal are usually lied on a slip plane (111), and are split into stacking fault surrounded by two partial dislocations. Tow dislocation indicated by 1 & 2 in (a) make a jog dislocation in (b). When a jog dislocation moves there leaves a chain of vacancy as a trail. MD is a powerful tools to observe the complicate interaction of moving atoms.

[Mechanical response of Au (001) nanoplate under uniaxial stress condition along [100] direction]

Under mechanical loading, metal nanoplates fail via elastic instability rather than the yield strength. As a result, we observed a unique “smaller is weaker” trend. We provided numerical and theoretical evidence to show that the nanoplates exhibit an intermediate mechanical regime that occurs between elasticity and plasticity, which we call the elastic instability regime.

[Stress-drop due to phonon scattering around dislocation core while it is in motion]

Unlike continuum, the motion of dislocation in nanoscale system induces unusual phenomenon. Through atomistic simulations, we observed that the internal effective stress of the system is always smaller than the externally applied stress during the dislocation motion. And we defined this unusual behavior as stress-drop for the first time. By using theoretical analysis, we proved that this behavior is induced by phonon scattering of elastic waves around anharmonic strain field of the core.

1. Development of FSI analysis technique and damage map for the prediction of disorder and the evaluation of damage of gas turbine, 2015. 07. 01 ~ 2017. 06. 30, KEPCO Research Institute (KEPRI), (Co-Pi, 88,000,000 Korean Won)
   가스터빈 고장예측 및 손상평가를 위한 연소-구조 연성해석기법 및 손상맵 개발, 2015. 07. 01 ~ 2017. 06. 30, 한국전력 전력연구원, (연구참여, 0.88억원)
2. Development of the NoNOx system of 1200~1800 Kw Marine Engines using supercomputers, 2015. 12. 01 ~ 2017. 09. 30, KIAT funded by the Ministry of Trade, Industry and Energy (MOTIE), (PI, 70,000,000 Korean Won)
   슈퍼컴퓨터를 활용한 1200~1800 KW Marine 엔진의 NoNOx 시스템 개발, 2015. 12. 01 ~ 2017. 09. 30, 산업통산자원부 (한국산업기술진흥원) (연구책임, 0.7억원)
3. Support for CAE Technology for Industries by Supercomputing, 2015.04.01 ~ 2016.03.31, Ministry of Science, Information and Future Planning (MSIP) (PI, 300,000,000 Korean Won)
   슈퍼컴퓨터를 활용한 산업체 CAE 기술 지원, 2015.04.01 ~ 2016.03.31, 미래창조과학부, (연구책임, 3억원)
4. Study on the Massive Computational Engineering and the Visualization of Largescale Scientific Data, 2015.04.01 ~ 2015.11.30, Korea Institute of Science and Technology Information (KISTI) (PI, 170,000,000 Korean Won)
   거대 계산공학 및 대용량 데이터 가시화 기술 연구, 2015.04.01 ~ 2015.11.30, 한국과학기술정보연구원, (연구책임, 1.7억원)
5. Development of Cooperation Service and Vitalization for Supercomputing Infrastructures, 2015.2.1 ~ 2015.12. 10, Korea Institute of Science and Technology Information (KISTI) (PI, 100,000,000 Korean Won)
   슈퍼컴퓨팅공동활용서비스및활성화연구, 2015.2.1 ~ 2015.12.10, 한국과학기술정보원, (연구책임, 1억원)
6. Multiscale Design Technology for Intelligent Materials Systems, 2014. 11.1~2017.10.31, Mid-Career Researcher Program by MSIP (PI, 612,000,000 Korean Won)
   지능재료시스템의멀티스케일설계기술개발, 2014. 11. 1 ~ 2017. 10. 31. 미래창조과학부중견연구자지원사업 (후속) (연구책임, 6억원)
7. Development of Cooperation Service and Vitalization for Supercomputing Infrastructures, 2014.1.1 ~ 2014.12. 10, Korea Institute of Science and Technology Information (KISTI) (PI, 100,000,000 Korean Won)
   슈퍼컴퓨팅 공동활용 서비스 및 활성화 연구, 2014.1.1 ~ 2014.12.10, 한국과학기술정보원, (연구책임, 1억원)
8. Creative Design Center for Human Oriented Future Mechanical Systems (BK21+), 2013.9.1 ~ 2019.12.31, Ministry of Education (Co-PI)
   인간친화 미래기계시스템 창의설계 연구 (BK21+), 2013.9.1 ~ 2019.12.31, 교육부, (연구참여)
9. Development of Cooperation Service and Vitalization for Supercomputing Infrastructures, 2013.1.10 ~ 2013.12. 10, Korea Institute of Science and Technology Information (KISTI) (PI, 100,000,000 Korean Won)
   슈퍼컴퓨팅 공동활용 서비스 및 활성화 연구, 2013.1.10 ~ 2013.12.10, 한국과학기술정보원, (연구책임, 1억원)
10. Development of Web Based Multi-scale Simulation Platform for the Efficient Design of Energy Nano Materials, 2012. 6. 1 ~ 2017. 5. 31, MNE (Co-PI)
    에너지용 나노소재의 효율적 설계를 위한 웹기반 멀티스케일 시뮬레이션 플랫폼 개발, 2012. 6. 1 ~ 2017. 5.31, 지식경제부 (참여연구)
11. Development of New Eco-Friend, High-Strength, Ultralight Materials Suitable for Blow Molding, 2012. 4. 15 ~ 2013. 12, Ulsan Techno Park & MEST (PI, 154,000,000 Korean Won)
    블러워 공법을 위한 친환경, 고강도, 경량화 신소재 연구, 2012. 4. 15 ~ 2013. 12.31, 울산테크노파크 & 교육과학기술부 (연구책임, 1억 5천4백만원)
12. Development of Education for Industry based on Ulsan Metropolitan Area (Environment Part), 2012. 3. 1 ~ 2012. 12. 31, Ulsan Techno Park & MEST (PI, 60,000,000 Korean Won)
    울산 지역거점기반 인력양성사업 (환경분야), 2012. 3. 1 ~ 2012. 12. 31, 울산테크노파크 (연구책임, 6천만원)
13. The Supporting of Supercomputing Operation and Vitalization for PSLI Partner Sites, 2012. 1.15~2012.12.10, Korea Institute of Science and Technology Information (KISTI) (PI, 100,000,000 Korean Won)
    PLSI 파트너 기관 운영 및 활성화 지원 사업, 2012. 1.15~2011.12.10, 한국과학기술정보연구원, (연구책임, 1억원)
14. Multiscale Design Technology for Intelligent Materials Systems, 2011. 9.1~2014.8.31, Mid-Career Researcher Program by MEST (PI, 600,000,000 Korean Won)
    지능재료 시스템의 멀티스케일 설계 기술 개발, 2011. 9.1~2014.8.31, 교육과학기술부 중견연구자지원사업 (연구책임, 6억원)
15. Analysis of Elastic Waves in Nanoplate, 2011. 5.1 ~ 2014. 4.30, Basic Career Researcher Program by MEST (PI, 150,000,000 Korean Won)
    나노 판 구조물에서의 탄성 파동 해석 연구, 2011. 5.1 ~ 2014. 4.30, 교육과학기술부 일반연구자지원사업 (연구책임, 1억 5천만원)
16. The Supporting of Supercomputing Operation and Vitalization for PSLI Partner Sites, 2011. 2.15~2011.12.15, Korea Institute of Science and Technology Information (KISTI) (PI, 100,000,000 Korean Won)
    PLSI 파트너 기관 운영 및 활성화 지원 사업, 2011. 2.15~2011.12.15, 한국과학기술정보연구원, (연구책임, 1억원)
17. Method for Optimizing the Cooling Design of Hot-Stamping Tools, 2010.12.1~2011.11.30, Hyundai Motors (Co-PI, 60,000,000 Korean Won)
    핫스탬핑 냉각설계 최적화 방안 연구, 2010.12.1~2011.11.30, 현대자동차 (참여연구, 6천만원)
18. A Study on the Interfacial Characteristics of 2D Nanomaterials, 2009.12.1~2010.11.30, UNIST (PI, 30,000,000 Korean Won)
    2차원 나노재료의 계면 특성 연구, 2009.12.1~2010.11.30, 울산과학기술대학교 (연구책임, 3천만원)