Ductile Fracture Behaviour under Mode I Loading Using Rousellier Ductile Damage Theory

Oh, Dong-Joon,Howard, I.C.,Yates, J.R. The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.9

The aim of this study is to investigate the ductile fracture behaviour under Mode I loading using SA533B pressure vessel steel. Experiments consist of the Round Notch Bar Test (RNB), Single Edge Crack Bending Test (SECB), and V-Notch Bar Test (VNB). Results from the RNB test were used to tune the damage modelling constant. The other tests were performed to acquire the J-resistance curves and to confirm the damage constants. Microstructural observation includes the measurement of crack profile to obtain the roughness parameter. Finally, simulation using Rousellier Ductile Damage Theory (RDDT) was carried out with 4-node quadrilateral element ($L_c=0.25\;mm$). For the crack advance, the failed element removal technique was adopted with a ${\beta}$ criterion. In conclusion, the predicted simulation using RDDT showed a good agreement with the experimental results. A trial using a roughness parameter was made for a new evaluation of J-resistance curve, which is more conservative than the conventional one.

Temporal-spatial structures of plasmas flows and turbulence around tearing mode islands in the edge tokamak plasmas

Zhao, K.J.,Nagashima, Y.,Li, F.M.,Shi, Yuejiang,Diamond, P.H.,Dong, J.Q.,Itoh, K.,Itoh, S.-I.,Zhuang, G.,Liu, H.,Chen, Z.P.,Cheng, J.,Nie, L.,Ding, Y.H.,Hu, Q.M.,Chen, Z.Y.,Rao, B.,Cheng, Z.F.,Gao, L. IOP 2017 Nuclear fusion Vol.57 No.12

<P>The temporal-spatial structures of plasma flows and turbulence around tearing mode islands are presented. The experiments were performed using Langmuir probe arrays in the edge plasmas of J-TEXT tokamak. The correlation analyses clearly show that the flows have similar structures of <I>m</I>/<I>n</I>  =  3/1 as the magnetic island does (<I>m</I> and <I>n</I> are the poloidal and toroidal mode numbers, respectively). The sign of the potential fluctuations for the flows inverses and the powers significantly reduce at <I>q</I>  =  3 surface. Approaching to the last closed flux surface for the magnetic islands, the radially elongated flow structure forms. The flows are concentrated near separatrix and show quadrupole structures. The turbulence is concentrated near X-point and partly trapped inside the magnetic islands.</P>

Response of plasma rotation to resonant magnetic perturbations in J-TEXT tokamak

Yan, W,Chen, Z Y,Huang, D W,Hu, Q M,Shi, Y J,Ding, Y H,Cheng, Z F,Yang, Z J,Pan, X M,Lee, S G,Tong, R H,Wei, Y N,Dong, Y B IOP 2018 Plasma physics and controlled fusion Vol.60 No.3

<P>The response of plasma toroidal rotation to the external resonant magnetic perturbations (RMP) has been investigated in Joint Texas Experimental Tokamak (J-TEXT) ohmic heating plasmas. For the J-TEXT’s plasmas without the application of RMP, the core toroidal rotation is in the counter-current direction while the edge rotation is near zero or slightly in the co-current direction. Both static RMP experiments and rotating RMP experiments have been applied to investigate the plasma toroidal rotation. The core toroidal rotation decreases to lower level with static RMP. At the same time, the edge rotation can spin to more than 20 km s<SUP>−1</SUP> in co-current direction. On the other hand, the core plasma rotation can be slowed down or be accelerated with the rotating RMP. When the rotating RMP frequency is higher than mode frequency, the plasma rotation can be accelerated to the rotating RMP frequency. The plasma confinement is improved with high frequency rotating RMP. The plasma rotation is decelerated to the rotating RMP frequency when the rotating RMP frequency is lower than the mode frequency. The plasma confinement also degrades with low frequency rotating RMP.</P>

Preparation and Properties of Barium Titanate Nanopowder/Epoxy Composites

Chandradass, J.,Bae, Dong-sik TaylorFrancis 2008 Materials and manufacturing processes Vol.23 No.2

<P> This article is focused on the preparation of barium titanate nanopowder/epoxy composites and studying the effect of barium titanate nanopowder on improving mechanical and thermal characteristics of the epoxy polymer. Composites are prepared by dispersing barium titanate nanopowder in epoxy resin and, subsequently, cross-linking by using diamino diphenyl methane (DDM) curing agents. Synthesis of barium titanate nanopowder/epoxy composites is carried out for different concentrations (1, 3, and 5 by weight) of barium titanate nanopowder at high temperature. High-temperature curing (HTC) involves mixing the resin-nanopowder solution followed by DDM hardener and curing at 120°C. Tensile, flexure, and impact results showed a maximum value of 72.7 MPa, 2.98 GPa, and 2 J/cm, respectively. DSC analysis revealed that curing occurs at low temperature in the presence of barium titanate nanopowder. Thermogravimetry analysis (TGA) showed the increased thermal stability in the nanoparticle filled epoxy composites as compared with the pure epoxy counterparts. Dynamic mechanical analysis (DMA) revealed, maximum storage modulus of 6400 MPa and glass transition temperature of 154°C for 3 wt% barium titanate nanopowder.</P>

구기자 및 구기엽 추출물의 피부과색소 조절효과

김동희 ( Dong Hee Kim ),이수연 ( Soo Yeon Lee ),김남경 ( Nam Kyung Kim ),윤보경 ( Bo Kyung Youn ),정다솜 ( Da Som Jung ),최은영 ( Eun Young Choi ),홍소리 ( So Ri Hong ),윤지영 ( Ji Young Yoon ),강명화 ( Myung Hwa Kang ),이진영 ( J 한국응용생명화학회(구 한국농화학회) 2011 Journal of Applied Biological Chemistry (J. Appl. Vol.54 No.4

구기자, 건조구기엽, 생구기엽 추출물의 미백효과를 검증하였다. Tyrosinase 저해활성 측정결과 건조구기엽 에탄올추출물 500 μg/mL에서 44%의 저해활성을 나타내었으며, melanoma cell (B16F10)에서의 melanin 생합성 저해율 측정결과 건조구기엽 에탄올 추출물 50 μg/mL에서 14%의 저해효과를 나타내었다. 구기자, 건조구기엽, 생구기엽 추출물을 처리한 B16F10군 에서는 tyrosinase protein의 발현이 처리하지 않은 군보다 감소 하였다. 특히, 건조구기엽 추출물의 경우 tyrosinase의 단백질 발현량을 많이 저해하였다. 결과적으로 건조구기엽 추출물의 미백활성이 가장 우수하였으며, 식품 및 화장품의 기능성 소재로 이용이 가능할 것으로 판단된다. The objective of the present study was to evaluate the skin whitening effect of the extracts, Lycii fructus (LF), Dry-L. foilum (DLF) and Fresh-L. folium (FLF). Tyrosinase inhibition activities was 44% in DLF ethanol extracts at a 500 μg/mL. When the tyrosinase activities in B16F10 murine melanoma cell were tested, the activities in DLF ethanol extracts was 14% at a 50 μg/mL concentration. The protein expression of microphthalmia-associated transcription factor, tyrosinase related protein 1 (TRP-1), TRP-2, and tyrosinase, which are all melanin related factors, showed that LF, DLF and FLF extracts inhibited the protein bio-synthesis in B16F10 melanoma cell. Especially the DLF extract showed greater decrease of protein expressions. Results indicate that the DLF extract tested in the present study had skin whitening activity and can be used as a function a ingredients for food and cosmetic compositions.

간호전공과 비 간호전공 여대생의 모유수유 지식과 태도, 실천 지속 의지에 대한 연구

김수정,김희진,동민영,박소민,송예슬,이고은,이승만,장지은,정유진,최예슬 이화여자대학교 간호과학대학 2013 이화간호학회지 Vol.- No.47

Purpose: This study was conducted as benchmark to improve breast-feeding educational programs by comparing knowledge, attitude, and practical volition between female nursing college students and non-nursing college students. Method: The survey was conducted on 236 female students from ‘E’ and ‘Y’ Universities which were located in Seoul. The sample consisted of 114 nursing and 122 non-nursing college students. The data were collected using self-administered questionnaires from October 25 to December 17, 2012. The collected data were analyze dusing SPSS20.0. Result: The nursing college students’ level of knowledge, attitude and practical volition toward breast feeding was higher than non-nursing college students. There was positive correlation between knowledge and practical volition and attitude and practical volition about breast-feeding in nursing college students. But non-nursing college students had positive correlation between knowledge and attitude, and knowledge and practical volition about breast-feeding. Conclusion: Based on the results of the research, there was a correlation between knowledge, attitude, and practical volition toward breast feeding. It was suggested that technical knowledge of breast feeding be offered to female college students, as well as nursing college students. It could help them have the right information on breast feeding. It was also suggested that educational programs to reinforce emotional⋅practical attitude based on the knowledge of breast feeding be developed. Also, this study suggested that female students get their practical education in breast feeding under any circumstances with the practical volition to breast feed. Improving the knowledge, attitude, and the practical volition toward breast feeding, will increase the rate of breast feeding.

유리系 內의 Ferrite의 Mossbauer Spectra

安振盛,金俊植,李敬行,趙壽烈,董徹,洪致裕 동국대학교 자연과학연구소 1984 자연과학연구 논문집 Vol.4 No.-

本 硏究는 5NiO-5CdO-10Fe₂O₃-30Na₂CO₃-10SiO₂(mole %)유리계에 대한 Mossbauer parameter의 溫度依存性을 조사하였다. Mossbauer spectrum은 한쌍의 Quadrupole doublet의 중첩으로 fitting하였으며 이중 하나는 tetrahedral site,다른 하나는 octahedral site이다. 상대적인 共鳴吸收面積比로부터 octahedral site와 tetrahedral site에 대한 Debye temperature를 계산하여 본 결과 각각 418K, 449K 임을 알았다. 또한 θ?값들을 이용해 least square method로 isomer shiftdral site의 壓力依存系數 α와 2.97×10?mm/sec K, I.S(0)일때의 를 평가해본 결과 octahedral site의 α는 2.97×10?mm/sec K,I.S(0)는 tetrahedral site이고 α의 3.2305×10?mm/sec K, I.S(0)는 0.276mm/sec임을 알았다. 그리고 quadrupole splitting은 측정온도가 증가함에 따라 서서히 감소함을 알았다. The temperature dependence of the Mossbauer parameter for 5NiO-5CdO-10Fe₂O₃-30Na₂CO₃-10SiO₂(mole %) quenched glass system was investigated. The spectra were fitted as superposition of a pair of quadrupole double ; One is for the tetrahedral site and the other is for the octahedral site. From the relative absorption area ratios of the spectra, the Debye erature of two sites were calculated to be 418K and 449K for the octahedral site and the ?edrai site, respectively. From these Debye temperatures, We can see that the isomer shifts and the coefficients αof the pressure dependence of the isomer shift are 0.456mm/sec, 2.97×10?mm/sec K for octahedral site and 0.276mm/sec K, 3.2305×10?mm/sec K for ?edral site. Also, we can see that the quadrupole splittings of two sites are gradually decresed the increase of the measuring temperature.

Deletions of 9p21 and TP53 in Bladder Cancer

Park, W.-S Korean Academy of Medical Science 1996 Journal of Korean medical science Vol.11 No.3

TiN, TiCN, CrN 박막의 고온 산화

백창현,홍주화,위명용,김기영,이동복 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.8

The oxidation behavior of TiN, TiCN and CrN coatings sputtered on a steel substrate was investigated at 850℃ in air. Both TiN and TiCN oxidized to Tio₂ while CrN oxidzed to Cr₂O₃. The oxidation resistance decreased in the order of CrN, TiN and TiCN. During oxidation, the outward diffusion of substrate elements such as Fe, Si occurred to a certain degree. The enrichment of substrate element of Cr at the oxide scale and the depletion of nitrogen at the lower part of the unoxidized CrN coating were observed.

박판주조법으로 제조된 Zr계 벌크 비정질 합금의 미세파괴기구

이정구,이동근,이성학,김낙준,조경목,박익민 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.2

The mechanical property improvement of a strip-cast Zr-base bulk amorphous alloy was explained by clarifying fracture mechanisms. Effects of crystalline phase particles formed in the amorphous matrix during strip casting on strength, ductility, and fracture toughness were explored in detail by directly observing microfracture processes using an in situ loading stage installed inside a scanning electron microscope (SEM) chamber. The compressive and fracture toughness test results indicated that ductility, strength, and fracture toughness of the atrip-cast amorphous alloy were higher than those of the as-cast monolithic amorphous alloy, although the strip-cast alloy contained a considerable amount (4.5 vol. %) of hard, brittle crystalline particles. This improvement of mechanical properties in the strip-cast alloy could be plausibly explained by mechanisms of (1) blocking of crack propagation, (2) formation of multiple shear bands, and (3) crack deflection by crystalline particles. Such property improvement presents new applicability of the strip-cast amorphous alloy containing crystalline particles to structures and components requiring excellent fracture toughness.