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RISS 인기검색어
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- 저자 : ( Guang Hui Liu ) (검색결과 33 건)
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In-plane vibration analysis of cantilevered circular arc beams undergoing rotational motion
Guang Hui Zhang,Zhan Sheng Liu,Hong Hee Yoo 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.1
Equations of motion of cantilevered circular arc beams undergoing rotational motion are derived based on a dynamic modeling method developed in this paper. Kane’s method is employed to derive the equations of motion. Different from the classical linear modeling method which employs two cylindrical deformation variables, the present modeling method employs a non-cylindrical variable along with a cylindrical variable to describe the elastic deformation. The derived equations (governing the stretching and the bending motions) are coupled but linear, so they can be directly used for vibration analysis. The coupling effect between the stretching and the bending motions, which could not be considered in the conventional modeling method, is considered in this modeling method. The effects of rotational speed, arc angle, and hub radius ratio on the natural frequencies of the rotating circular arc beam are investigated through numerical analysis.
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In-plane Vibration Analysis of Rotating Cantilever Curved Beams
Guang Hui Zhang,Zhan Sheng Liu,Hong Hee Yoo 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Equations of motion of rotating cantilever curved beams are derived based on a dynamic modeling method developed in this paper. The Kane’s method is employed to derive the equations of motion. Different from the classical linear modeling method which employs two cylindrical deformation variables, the present modeling method employs a non-cylindrical variable along with a cylindrical variable to describe the elastic deformation. The derived equations (governing the stretching and the bending motions) are coupled but linear. So they can be directly used for the vibration analysis. The coupling effect between the stretching and the bending motions which could not be considered in the conventional modeling method is considered in this modeling method. The natural frequencies of the rotating curved beams versus the rotating speed are calculated for various radii of curvature and hub radius ratios.
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QI-HUI SHEN,YAN LIU,XI YU,XIAO-YANG LIU,MING-QIANG ZOU,JIN-FENG LI,JIAN-GUANG ZHOU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.6
II?VI Semiconductor nanocrystals (NCs) with tunable visible emission, such as CdS, CdSe and CdTe, were synthesized in aqueous solution using thiols as capping molecules. Hydrazine was found to promote the growth of NCs through a special mechanism. In only a few hours, the synthesis process was completed at room temperature. Under moderate conditions, the capping molecules not only changed the growth rate of NCs simply by varying the concentration, but also altered the spectral properties of NCs. The capping molecules with amino groups were propitious to the growth of CdS NCs, whereas the kinetic growth of CdS NCs was more a®ected by the surface passivation e±ciency of NCs than by steric hindrance in the system. The fastest growth of the CdS NCs was achieved when glutathione was used as a capping molecule, while the emission of CdS and CdSe NCs were shown to remain steady and tunable using the same capping molecule. The growth rate of 3-mercaptopropionic acid-capped CdS and CdSe NCs slowed down signi¯-cantly, while CdTe NCs were obtained with excellent emission properties when capped with the same molecule. Furthermore, our approach will also be useful for the study of the kinetic growth of NCs in aqueous solution.
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Metrological performance investigation of swirl flowmeter affected by vortex inflow
Qi Liu,Jia-hui Ye,Guang Zhang,Zhe Lin,Hong-guang Xu,Zu-chao Zhu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.6
In fluid transportation industries, long straight transition pipelines upstream of flowmeters are required to eliminate the influence of disturbed inflow on flow metering accuracy. To ensure an accurate flow measurement, the straight transition pipeline, which is often lengthy, can be shortened, particularly when the installation space is limited. However, the characteristics of disturbed flow (mainly characterized by vortex inflow) evolving along the straight transition pipeline to affect the metrological performance must be investigated for optimizing the pipeline length. The objective of this study was to investigate the metrological performance of a swirl flowmeter affected by the vortex inflow caused by flow regulation with a sleeve valve. The effect of a straight transition pipeline length upstream of a swirl flowmeter on the evolving characteristics of the vortex inflow was investigated experimentally and by conducting a numerical simulation under flow regulation parameters, including valve openings and flow velocities. The flow coefficients for different straight transition pipeline lengths were investigated to verify the flow simulation. The periodic pressure variation in the swirl flowmeter was monitored and its corresponding characteristic frequency was analyzed. It was found that the metrological characteristics of the swirl flowmeter were extremely affected by a smaller valve opening, which can be improved by lengthening the straight transition pipeline. By analyzing the velocity vector and vorticity in the internal flow field, the vortex inflow was found to be vulnerable to dissipation within a longer straight transition pipeline. The average vorticity at the cross-section of the entrance to the swirl flowmeter was adopted to evaluate the inflow vortex intensity. Additionally, a power curve model was established to assess the critical characteristic frequency determined by the maximum unaffected inflow vorticity for different straight transition pipeline lengths. This study can provide helpful insights to the metrological performance and pipeline arrangement in the field of fluid transportation engineering.
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Ri-guang Jin,Shuang Kun Zhang,Wei Wei Liu,Hui Bo Zhang,Seung Kon Ryu 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.3
Molecular weight distribution of copolyacrylonitrile, which was obtained from precipitation copolymerization without and with using dispersants in mixed solution, is studied. The contribution ratio of liquid phase polymerization and solid phase polymerization under different polymerization conditions could be worked out through the formula,which has been deduced in literature. From the calculated results, common points of each reaction system are, i) contribution ratio (r) of solid phase to liquid phase decreases with the increase of water content; thus the solid phase polymerization is gradually strengthened, which is apt to form chain of high molecular weight, ii) the higher temperature leads to higher compatibility between water and DMSO; thus the solid phase polymerization contribution would decrease,while the value of r is considerably larger. The limit molecular weight distribution of the system without dispersants in 100% water is approaching to 2; thus the corresponding r becomes larger, the molecular weight distribution ratio (Q) decreases in the system with dispersants.
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Effect of Temperature on Resistivity of CFRP Materials with Added Carbon Powder or Nano-silica
Dan Liu,Jie Yin,Rong-gui Liu,Shu Ping,Hui-guang Yin,Gui-hua Xie 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.4
This paper presents an experimental investigation on the effect of temperature on resistivity of Carbon Fiber Reinforced Polymer (CFRP) materials. A series of tests were conducted on three types of CFRP materials, namely pure CFRP material, CFRP with carbon powder (4% in weight) and CFRP with nano-silica (4% in weight). Test results showed that adding carbon powder into the epoxy resin decreases the initial electric resistance R0 and initial volume resistivity ρ0 while adding nano-silica increases R0 and ρ0 compared to pure CFRP material. Preheating cycle test results showed that the volume resistivity of all three types of specimens linearly increases with increasing temperature. CFRP with added nano-silica exhibits higher temperature sensitivity than CFRP with added carbon powder compared to the lowest temperature sensitivity for pure CFRP material. In addition, temperature cycle test results showed that CFRP specimens have approximately stable values of volume resistivity. Both CFRP specimens with added carbon powder or nano-silica exhibit a recognizable trend of first decrease and then increase in volume resistivity with increasing temperature both during heating and cooling cycles. CFRP with added carbon powder mainly shows Negative Temperature Coefficient (NTC) effect in the temperature range of −40 to 40oC and Positive Temperature Coefficient (PTC) effect from 40 to 80oC. CFRP with added nano-silica mainly exhibits PTC effect in the temperature domain of −15 to 80oC and NTC effect from −40 to −15oC. A mathematical-physical model with respect to the thermal effect was presented based on the Eshelby-Mori-Tanaka (EMT) approach and mesomechanics method. The results obtained with the model agree well with the test results considering the temperature domain of PTC effect, which indicates that the proposed model is effective in characterizing the variation of fractional change in resistance (ΔR/R0) at varying temperature.
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Periodicity and attractivity for a rational recursive sequence
Lijie Zhang,Guang Zhang,Hui Liu 한국전산응용수학회 2005 Journal of applied mathematics & informatics Vol.19 No.1-2
In this paper, the existence of periodic positive solution and the attractivity are investigated for the rational recursive sequence xn+1 =(A + axn−k)/(b + xn−l), where A, a and b are real numbers, k and l are nonnegative integer numbers.
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Zhang, Bing-Hui,Liu, Wei,Li, Liang,Lu, Jian-Guang,Sun, Ya-Nan,Jin, De-Jun,Xu, Xiu-Yu Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.6
Objective: The current study explored the expression of KAI1/CD82 and MRP1/CD9 and its significance in laryngeal squamous cell carcinoma (LSCC). Methods: The expression levels of KAI1/CD82 and MRP1/CD9 in 100 LSCC tissue specimens, as well as in 30 para-LSCC non-carcinomatous tissue specimens randomly taken from the patients, were assessed using the quantitative polymerase chain reaction (Q-PCR) and immunohistochemistry and correlations with pathological parameters of LSCC and their influence on survival function were analyzed. Results: KAI1/CD82 and MRP1/CD9 showed basically consistent changes in both mRNA and protein expression. Their expression in the 30 LSCC specimens was significantly lower compared with that in the corresponding non-carcinous tissues (P < 0.01 or 0.05), notably correlating with TNM stage, differentiation degree, clinical stage, and lymphatic metastasis (P < 0.01 or 0.05), but not gender, age, and LSCC growth sites (P > 0.05). The median survival of patients with positive KAI1/CD82 and MRP1/CD9 protein expression was longer than that of patients with negative protein expression (P < 0.01 or 0.05). KAI1/CD82 protein expression negatively correlated with MRP1/CD9 protein expression in LSCC (${\chi}^2$= 31.25, P < 0.01). Conclusion: KAI1/CD82 and MRP1/CD9 may jointly participate in the development of LSCC. They may serve as the markers for judging the infiltration, metastasis, and prognosis of LSCC.
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