http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
오늘 본 자료
수정된 Chaboche 이동 경화 모델의 수치 구현과 압입라체팅 FE 해석
한정무,MARIMUTHU KARUPPASAMY PANDIAN,이형일 대한기계학회 2020 大韓機械學會論文集A Vol.44 No.1
Mechanical components operating under cyclic loading conditions exhibit multiaxial ratcheting behavior. The kinematic hardening model supported by commercial finite element (FE) software (Abaqus, Ansys) is limited to the initial theory and is not applicable to multiaxial ratcheting analysis. However, the modified kinematic hardening model, which is suitable for multiaxial conditions, is difficult to numerically implement because of the existence of complex constitutive relationships, such as those related to the added multiaxial dependence term and hardening law. In this study, the modified Chaboche kinematic hardening model was numerically implemented by using the framework of a small-strain, elastic-plastic theory; then, the applicability to multiaxial ratcheting analysis was explored by performing indentation ratcheting FE analysis. The numerical model can be practically applied to the analysis of multiaxial ratcheting caused by cyclic indentation, as well as biaxial ratcheting. 반복 하중 조건에서 작동하는 기계 요소들은 다축 반복 하중에 의한 다축라체팅 거동을 보인다. 상용 해석 소프트웨어(Abaqus, Ansys)에서 지원하는 이동 경화 모델은 초기 이론에 제한돼 다축라체팅 분석이 불가능하다. 반면, 다축 조건에 적합한 수정된 이동 경화 모델은 기존 모델에서 추가된 다축항과 경화 법칙 등 복잡한 구성 관계식으로 인해 수치 구현이 난해하다. 본 연구에서는 소변형 탄소성 이론에 입각해 수정된 Chaboche 이동 경화 모델에 대해 Abaqus(6.13 ver)로의 효과적인 수치 구현과 검증 방법을 제안하고, 이를 이용한 압입라체팅 유한요소해석을 수행함으로써 다축라체팅 분석에 대한 활용성을 제시한다. 본 연구로부터 수치 구현된 이동 경화 모델은 반복 압입으로 발생하는 다축라체팅 분석에 실용적으로 활용될 수 있다.
Imaging Technologies for Microfluidic Biochips
한정무,강운교,문은이,유홍기,권보미 한국바이오칩학회 2022 BioChip Journal Vol.16 No.3
With the growing interest in biochips, numerous efforts have been made to recapitulate a more reliable and physiologically relevant environment within chips, resulting in significant advances in biochip technologies. Although there have been substantial improvements in biochip fabrication technologies, less effort has been devoted to improving imaging or microscopic methods specialized for observing in-chip structures. As biochip structures become increasingly sophisticated and the complexity of scaffolds mixed with cells and the extracellular matrix grows, the demand for customized imaging technology for biochips is expected to increase rapidly. In response to these demands, in this review, we briefly introduce various imaging technologies based on the complexity and size of imaging targets embedded in the chip.
CNG 저장용기용 저합금강의 인장 특성에 미치는 고압 수소가스의 영향
이해무(H. M. Lee),정인현(I. H. Jeong),박종서(J. S. Park),남승훈(S. H. Nahm),한정옥(J. O. Han),이영철(Y. C. Lee) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.8
대체천연가스(SNG)는 에너지 안보 차원에서 에너지 수급 안정화 방안의 하나로 많은 관심을 받고 있다. 또한 HCNG (또는 H₂CNG)는 배기가스 내의 유해 성분을 현저히 줄이고 열효율도 높일 수 있어서 내연기관이나 가정용 연료로 사용될 것으로 기대되고 있다. 그러나 SNG나 HCNG에 포함되어 있는 수소는 재료에 침투하여 그 재료의 역학적 특성을 크게 저하시키는 것으로 알려져 있다. 따라서 SNG나 HCNG를 안전하고 효율적으로 수송ㆍ공급하려면 이를 위해 운용되는 인프라의 안전성과 신뢰성 확보가 선결되어야 한다. 본 연구에서는 중공 시험편을 이용한 인장시험법을 통하여 CNG 저장용기용 저합금강이 나타내는 고압 수소 분위기에서의 인장 특성 변화에 대하여 조사하였다. SNG (synthetic natural gas or substitute natural gas) could contribute greatly toward energy security. In addition, HCNG (or H₂CNG) is expected to be used as a fuel gas for internal combustion engines and home appliances because it has extremely low emissions and high thermal efficiency. However, the hydrogen contained in SNG or HCNG can deteriorate the mechanical properties of the materials used in existing natural gas infrastructure. Therefore, it is necessary to investigate the effect of hydrogen on the mechanical properties of such materials so that SNG or HCNG can be transported and distributed safely and reliably. In this study, the effect of highly pressurized hydrogen gas on the tensile properties of a low-alloy steel used for manufacturing CNG storage vessels was investigated using the so-called hollow tensile specimen technique.
CNG 저장용기용 저합금강의 인장 특성에 미치는 고압 수소가스의 영향
이해무(H. M. Lee),정인현(I. H. Jeong),박종서(J. S. Park),남승훈(S. H. Nahm),한정옥(J. O. Han),이영철(Y. C. Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Natural gas that can be produced from coal or biomass is known as “synthetic natural gas” or “substitute natural gas” (SNG). SNG could be a major driver for energy security. SNG production could diversify energy options and reduce natural gas imports. Also, HCNG (or H₂CNG), a mixture of CNG(compressed natural gas) and 4-9 percent hydrogen by energy, is expected to be used as a fuel gas for internal combustion engines and home appliances due to extremely low emissions and increases in thermal efficiency. However, mechanical properties can be deteriorated by hydrogen contained in SNG or HCNG. It is necessary, therefore, to investigate the effect of hydrogen on the mechanical properties of materials used for the existing natural gas infrastructure so that SNG or HCNG can be transported and distributed safely and reliably. In this study, the effect of highly pressurized hydrogen gas on tensile properties of a low alloy steel used for CNG storage vessels was investigated using so-called hollow tensile specimen technique.
2형 신경섬유종증에서 양측 소뇌다리뇌각종양으로 인한 양측 전정병증
김준엽,남정무,한정호,김지수 대한신경과학회 2010 대한신경과학회지 Vol.28 No.1
Bilateral vestibulopathy (BV) is characterized by oscillopsia and imbalance during locomotion. Half of the cases of BV are idiopathic, and BV due to brain tumor has been reported only rarely. We report a case of BV due to bilateral cerebellopontine-angle tumors in a patient with neurofibromatosis type 2. Careful history on oscillopsia and imbalance during locomotion, and regular follow-ups using the head-impulse test and dynamic visual acuity are warranted in patients with neurofibromatosis type 2.
정의환(Uihwan Jeong),한정무(Jungmoo Han),Karuppasamy Pandian Marimuthu,이영서(Lee Youngseo),이형일(Hyungyil Lee) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12
Despite the excellent mechanical properties, practical application of bulk metallic glasses (BMGs) is limited due to difficulties in fabricating bulk products from BMG. Alternatively, BMGs are deposited as thin film on substrates i.e. thin-film metallic glass (TFMG) for utilizing their mechanical performances. As tensile or compression testing at nanoscale is infeasible for mechanical characterization, we use nanoindentation tests to investigate the nanomechanical behavior of Zr-TFMG deposited on various substrates. The deformation behaviors of Zr-TFMG and mechanical properties are then analyzed through finite element (FE) simulations. The effects of peak and cyclic loads and loading rate on the nanomechanical properties are investigated. Observation of significant pile-up of TFMG on Si substrate demonstrates that the deformation behavior of Zr-TFMG is affected by substrate material. Finally, based on the experimental and numerical nanoindentation studies, the nanomechanical properties of Zr-TFMG were evaluated.