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김석현,박무열,최승훈 강원대학교 산업기술연구소 2007 産業技術硏究 Vol.27 No.A
A theoretical model based on Rayleigh-Ritz method is proposed to predict the resonance frequency of a W/T(Wind Turbine) tower structure supported by guy cables. In order to verify the validity of the theoretical model, a reduced W/T tower system is manufactured and tested. Frequency response and mode data are determined by modal testing and finite element analysis is performed to calculate the natural frequency of the tower model. Numerical and experimental results are compared with those by the theoretical analysis. Parametric study by the theoretical model shows how the cable tension and cable elasticity influence the resonance frequency of the W/T tower structure. Finally, vibration response under various rotating speed is investigated to examine the possibility of severe resonance.
G. Z. YANG,H. CUI,C. X. WANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.5
Density-controlled single-crystalline β-SiC nanotubes were successfully synthesized on a large scale by adding Zn into the system via direct thermal evaporation of C60 onto silicon wafers at 1290°C. Interestingly, no Zn elements can be detected in the final products. However, the addition of Zn power is important because without Zn, density-controlled SiC nanotubes cannot be observed in our experiment. On the basis of the results, a possible growth mechanism was proposed to illustrate the role that Zn played in the growth process. The field emission and hydrophobic performances show strong dependence on the densities of as-synthesized β-SiC nanotubes. The density-controlled β-SiC nanotubes with tunable field emission and hydrophobic properties may have potential in the future of nanotechnology.
Tailoring the Impact Toughness of Sintered NdFeB Magnets via Surface Coating
X. G. Cui,J. X. Pan,C. Y. Cui,P. Mei,X. H. Wang,C. Fang,T. Y. Ma,C. Wang,X. C. Peng 한국자기학회 2018 Journal of Magnetics Vol.23 No.1
Metallic coating by electroplating is commonly attractive for improving the corrosion resistance of sintered NdFeB magnets. However, its tailoring of mechanical characteristics for sintered NdFeB magnets has been seldom concerned. Herein, the impact toughnesses of sintered NdFeB magnets with various metallic coatings (Ni or Ni/Sn) were comparatively investigated. The results indicate that the impact toughnesses of sintered NdFeB magnets are both improved by Ni coating and Ni/Sn bilayer coating. And Ni/Sn bilayer coating exhibits more enhancement of the impact toughness, increased by 41.6% compared with the original magnet. Moreover, the microstructural observations of the metallic coatings and the fracture were conducted, and the enhanced mechanism of impact toughness for the magnet is analyzed. These findings may provide a reference for toughening the brittle materials.
Thermodynamic Analysis of Intergranular Additives in Sintered Nd-Fe-B Magnet
X. G. Cui,X. H. Wang,C. Y. Cui,G. C. Yin,C. D. Xia,X. N. Cheng,X. J. Xu 한국자기학회 2017 Journal of Magnetics Vol.22 No.2
To get deeper insight into the effect of intergranular additives in sintered Nd-Fe-B magnet and consequently improve the properties better, the interaction between additives (oxide, nitride, and carbide) and Nd-rich phase in the temperature range of 298.15-1400 K was analyzed thermodynamically. It can be found that the oxide additives became less stable than nitrides and carbides. Except for calcium oxide, almost all oxides could react with Nd from Nd-rich phase. To be different from oxide additives, the mechanism of nitrides and carbides was defined with various elements, either reaction with Nd from Nd-rich phase or not. The two different mechanisms would show different effects on the microstructure and hence properties of magnet. The thermodynamic analysis had a better agreement with the experimental information.
Han, J.,Wang, Q.C.,Zhu, C.C.,Liu, J.,Zhang, Y.,Cui, X.S.,Kim, N.H.,Sun, S.C. Academic Press 2016 Toxicology and applied pharmacology Vol.300 No.-
Deoxynivalenol (DON) is a widespread trichothecene mycotoxin which contaminates agricultural staples and elicits a complex spectrum of toxic effects on humans and animals. It has been shown that DON impairs oocyte maturation, reproductive function and causes abnormal fetal development in mammals; however, the mechanisms remain unclear. In the present study, we investigate the possible reasons of the toxic effects of DON on porcine oocytes. Our results showed that DON significantly inhibited porcine oocyte maturation and disrupted meiotic spindle by reducing p-MAPK protein level, which caused retardation of cell cycle progression. In addition, up-regulated LC3 protein expression and aberrant Lamp2, LC3 and mTOR mRNA levels were observed with DON exposure, together with Annexin V-FITC staining assay analysis, these results indicated that DON treatment induced autophagy/apoptosis in porcine oocytes. We also showed that DON exposure increased DNA methylation level in porcine oocytes through altering DNMT3A mRNA levels. Histone methylation levels were also changed showing with increased H3K27me3 and H3K4me2 protein levels, and mRNA levels of their relative methyltransferase genes, indicating that epigenetic modifications were affected. Taken together, our results suggested that DON exposure reduced porcine oocytes maturation capability through affecting cytoskeletal dynamics, cell cycle, autophagy/apoptosis and epigenetic modifications.
Observation of the topological surface state in the nonsymmorphic topological insulator KHgSb
Liang, A. J.,Jiang, J.,Wang, M. X.,Sun, Y.,Kumar, N.,Shekhar, C.,Chen, C.,Peng, H.,Wang, C. W.,Xu, X.,Yang, H. F.,Cui, S. T.,Hong, G. H.,Xia, Y.-Y.,Mo, S.-K.,Gao, Q.,Zhou, X. J.,Yang, L. X.,Felser, C. American Physical Society 2017 Physical review. B Vol.96 No.16
<P>Topological insulators represent unusual topological quantum states, typically with gapped bulk band structure but gapless surface Dirac fermions protected by time-reversal symmetry. Recently, a distinct kind of topological insulator resulting from nonsymmorphic crystalline symmetry was proposed in the KHgX (X = As, Sb, Bi) compounds. Unlike regular topological crystalline insulators, the nonsymmorphic glide-reflection symmetry in KHgX guarantees the appearance of an exotic surface fermion with hourglass shape dispersion (where two pairs of branches switch their partners) residing on its (010) side surface, contrasting to the usual two-dimensional Dirac fermion form. Here, by using high-resolution angle-resolved photoemission spectroscopy, we systematically investigate the electronic structures of KHgSb on both (001) and (010) surfaces and reveal the unique in-gap surface states on the (010) surface with delicate dispersion consistent with the 'hourglass Fermion' recently proposed. Our experiment strongly supports that KHgSb is a nonsymmorphic topological crystalline insulator with hourglass fermions, which serves as an important step to the discovery of unique topological quantum materials and exotic fermions protected by nonsymmorphic crystalline symmetry.</P>
In Vitro Endothelialization on CNx Films Deposited on PTFE
X. L. Qing,F. Z. Cui,C. L. Zheng 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1
Endothelial cells were successfully seeded onto carbon nitride (CNx) ¯lms deposited on poly-tetra°uoroethylene (PTFE) by using the ion beam-assisted deposition (IBAD) technique. X-ray photoelectron spectroscopy and, Raman characterization of the resulting ¯lms showed that IBAD was e±cient in fabricating CNx ¯lms with controllable nitrogen content and sp2=sp3 fraction. The 48 hr cell culture indicated the endothelial cells grew best on CNx ¯lm with greatest nitrogen content. The CNx-coated PTFE may be a promising vascular prosthesis in vascular reconstruction.