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      • KCI등재후보
      • KCI등재

        Design of a Three Dimensional Folded Monopole Antenna Using Current Flow

        Yulin Liu,Seungwoo Lee,Nam Kim 한국전자파학회JEES 2010 Journal of Electromagnetic Engineering and Science Vol.10 No.2

        A new type of monopole antenna whit broadband characteristics is presented in this article. To reduce the size of the antenna, its upper part is folded. By separating the current flow, the resonance in the shorter part is in the higher band; and the longer part resonates in the lower band. This gives the broadband characteristics of the antenna. Slots on the corner using an oblique line improve the impedance matching and bandwidth. The measurement results show that the bandwidth operates from 0.848~0.992 ㎓ and 1.744~2.528 ㎓, and the radiation patterns are in an omni-directional shape.

      • KCI등재

        Numerical analysis of flow in a Francis turbine on an equal critical cavitation coefficient line

        Yulin Wu,Jintao Liu,Yuekun Sun,Shuhong Liu,Zhigang Zuo 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.6

        Numerical simulation and model test were applied to study the cavitation flow in Francis turbines. The SST k-ω turbulence model and the mixture model were used to simulate the cavitating flow in the Francis turbine. An equal critical cavitation coefficient line was calculated and the flow in the Francis turbine was analyzed. Simulation results show reasonable agreement with the experimental data. It is confirmed that these cavitation model and numerical method is a useful way to study the two-phase cavitation flow in Francis turbines. On the equal critical cavitation coefficient line, the energy loss in the turbine may be caused by the rotating of vortex rope in the draft tube or flow separation in the runner. The study of equal critical cavitation coefficient line can provide a basic guidance for industry practice.

      • KCI등재

        Three-dimensional flow simulation of transient power interruption process of a prototype pump-turbine at pump mode

        Jintao Liu,Shuhong Liu,Yuekun Sun,Lei Jiao,Yulin Wu,Leqin Wang 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

        The transient power failure process of a prototype pump-turbine was studied numerically by three-dimensional (3-D) simulations. Fluid coupling and dynamic mesh (DM) method were used to calculate the rotational speed of the runner. Simulations were performed based on turbulence model. Specific transient characteristics, such as the flow rate, head, rotational speed, were analyzed. The pumpturbine had a minimum head and a maximum axial force when the flow rate was 0 during the transient process. Pressure fluctuations increased when the pump-turbine ran at pump braking mode. Reverse flow in the casing as well as stall phenomenon in the runner had a great effect on the change of head. Pressure in the runner was greatly reduced when the pump-turbine ran at pump braking mode. The computational method could be used to interpret the abnormal phenomenon by the analysis of flow mechanism during a transient process.

      • KCI등재

        Role of Estrogen Receptor-α in the Regulation of Claudin-6 Expression in Breast Cancer Cells

        Liu Yafang,Wu Qiong,Ren Yue,Xu Xiaoming,Yu Lina,Zhang Mingzi,Zhang Ting,Li Yulin,Quan Chengshi 한국유방암학회 2011 Journal of breast cancer Vol.14 No.1

        Purpose: In our previous studies we showed that upregulating claudin-6 (CLDN6) expression may contribute to preventing breast cancer, and that 17β-estradiol induces a concentration- and time-related effect on CLDN6 mRNA and protein expression in MCF-7 cells. However, the mechanisms of 17β-estradiol regulation of CLDN6 are still unclear. We determined the role of estrogen receptors in the regulation of CLDN6 expression in human breast cancer tissues and a cell line. Methods: CLDN6, estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) expression in breast cancer tissues were examined using immunohistochemistry. The human breast cancer cell line, MCF-7, which expresses ERα but not ERβ was used. CLDN6 and ERα expression were measured by reverse transcriptase-PCR, Western blotting and immunofluorescent staining. Treatments with propyl pyrazole triol (PPT) and ICI 182, 780 (ICI) were performed. Results: The results revealed that CLDN6 expression was related to ERα in breast cancer tissues (p=0.033). PPT, an ERα-selective ligand, upregulated CLDN6 expression at 10^(-5) mol/L after 24 hours. The effect of PPT on regulating CLDN6 expression in MCF-7 cells was blocked by ICI. Conclusion: These findings suggest that Erα reulates CLDN6 expression in breast cancer tissues and that 17β- estradiol induces CLDN6 expression through an ERα pathway in MCF-7 cells.

      • KCI등재후보

        An analytical solution to the vibration characteristics for continuous girder bridge-track coupling system and its application

        Yulin Feng,Lizhong Jiang,Wangbao Zhou,Yuntai Zhang,Xiang Liu 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.77 No.5

        To study the vibration characteristics of a high-speed railway continuous girder bridge-track coupling system (HSRCBT), a coupling vibration analysis model of an m-span continuous girder bridge-subgrade-track system with n-span approach bridge was established. The model was based on the energy and its variational method, where both the interlaminar slip and shear deformation effects were considered. In addition, the free vibration equations and natural boundary conditions of the HSRCBT were derived. Further, according to the coordination principle of deformation and mechanics, an analytical method for calculating the natural vibration frequencies of the HSRCBT was obtained. Three typical bridge-subgrade-track coupling systems of high-speed railway were taken and the results of finite element analysis were compared to those of the analytical method. The errors between the simulation results and calculated values of the analytical method were less than 3%, thus verifying the analytical method proposed in this paper. Finally, the analytical method was used to investigate the influence of the number of the approach bridge spans and the interlaminar stiffness on the natural vibration characteristics of the HSRCBT based on the degree of sensitivity. The results suggest the approach bridges have a critical number of spans and in general, the precision requirements of the analysis could be met by using 6-span approach bridges. The interlaminar vertical compressive stiffness has very little influence on the low-order natural vibration frequency of HSRCBT, but does have a significant influence on higher-order natural vibration frequency. As the interlaminar vertical compressive stiffness increases, the degree of sensitivity to interlaminar stiffness of each of the HSRCBT natural vibration characteristics decrease and gradually approach zero.

      • KCI등재

        Comparison of long-term behavior between prestressed concrete and corrugated steel web bridges

        Yulin Zhan,Fang Liu,Zhongguo John Ma,Zhiqiang Zhang,Zengqiang Duan,Ruinian Song 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.6

        Prestressed concrete (PC) bridges using corrugated steel webbing have emerged as one of the most promising forms of steel-concrete composite bridge. However, their long-term behavior is not well understood, especially in the case of largespan bridges. In order to study the time-dependent performance, a large three-span PC bridge with corrugated steel webbing was compared to a similar conventional PC bridge to examine their respective time-dependent characteristics. In addition, a threedimensional finite element method with step-by-step time integration that takes into account cantilever construction procedures was used to predict long-term behaviors such as deflection, stress distribution and prestressing loss. These predictions were based upon four well-established empirical creep prediction models. PC bridges with a corrugated steel web were observed to have a better long-term performance relative to conventional PC bridges. In particular, it is noted that the pre-cambering for PC bridges with a corrugated steel web could be smaller than that of conventional PC bridges. The ratio of side-to-mid span has great influence on the long-term deformation of PC bridges with a corrugated steel web, and it is suggested that the design value should be between 0.4 and 0.6. However, the different creep prediction models still showed a weak homogeneity, thus, the further experimental research and the development of health monitoring systems are required to further progress our understanding of the long-term behavior of PC bridges with corrugated steel webbing.

      • KCI등재

        Identification and expression analysis of ERECTA family genes in grape (Vitis vinifera L.)

        Min Liu,Wanping Li,Zhuo Min,Xianghan Cheng,Yulin Fang 한국유전학회 2019 Genes & Genomics Vol.41 No.6

        Background ERECTA family (ERf) genes are found in many dicots and monocots, and play important roles in plant developmental processes and stress responses. However, there is little known on ERf genes in grape (Vitis vinifera L.). Objectives The primary objective of this study was to identify the ERf genes in grape, and to analyze their expression profiles in different organs, during development, and in response to hormone treatments and abiotic/biotic stresses. Methods ERf protein sequences of dicots were aligned in the grape genome (V. vinifera cv. Pinot Noir, PN40024, 12X) with Blast server. The locus tags obtained were inputted in NCBI to retrieve corresponding nucleotide and protein accession numbers. The subcellular localization experiment was performed by the transient expression of VvERECTA-GFP and VvERL2-GFP in mesophyll protoplasts of Arabidopsis. The expression levels of ERf genes in grape leaves were detected by qRT-PCR after hormone treatments and abiotic/biotic stresses. Results We first identified the ERf genes in the grape genome, including VvERECTA and VvERL2. Their cDNA full-length sequences were obtained with the accession numbers MG601756 and MG601757. The result of subcellular localization indicated that the fusion proteins of VvERECTA and VvERL2 were localized in the plasma membrane. There were four conserved domains identified in VvERECTA and VvERL2, including a LRRNT-2, a LRR, a transmembrane and a protein kinase domain. The grape ERf genes expressed highly in young aboveground organs. As grape leaves or berries becoming mature, VvERECTA expressed in a declining trend. The transcript abundance of VvERL2 decreased during leaves development, but showed no significant differences during berries development. The hormone treatments of ABA, SA, MeJA and BR could induce the expression of VvERECTA and VvERL2. The treatments of heat, drought, downy and powdery mildew significantly increased the expression levels of the grape ERf genes. Conclusion The grape ERECTA gene family might play crucial roles in response to abiotic and biotic stresses. We provide the first description of the grape ERf genes and the most comprehensive analysis of their expressions in different biological processes.

      • SCOPUSKCI등재

        Experimental Study on Internal Flow of a Mini Centrifugal Pump by PIV Measurement

        Wu, Yulin,Yuan, Huijing,Shao, Jie,Liu, Shuhong Korean Society for Fluid machinery 2009 International journal of fluid machinery and syste Vol.2 No.2

        The internal flow field in a centrifugal pump working at the several flow conditions has been measured by using the particle image velocimetry (PIV) technique with the laser induced fluorescence (LIF) particles and the refractive index matched (RIM) facilities. The impeller of the centrifugal pump has an outlet diameter in 100mm, and consists of six two-dimensional curvature backward swept blades of constant thickness. Measured results give reliable flow patterns in the pump. It is obvious that application of LIF particle and RIM are the key methods to obtain the right PIV measured results in pump internal flow.

      • Evaluation of optimal ground motion intensity measures of high-speed railway train running safety on bridges during earthquakes

        Xiang Liu,Lizhong Jiang,Ping Xiang,Yulin Feng,Zhipeng Lai,Xiaoyun Sun 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.2

        Due to the large number of railway bridges along China's high-speed railway (HSR) lines, which cover a wide area with many lines crossing the seismic zone, the possibility of a HSR train running over a bridge when an earthquake occurs is relatively high. Since the safety performance of the train will be threatened, it is necessary to study the safety of trains running over HSR bridges during earthquakes. However, ground motion (GM) is highly random and selecting the appropriate groundmotion intensity measures (IMs) for train running safety analysis is not trivial. To deal this problem, a model of a coupled trainbridge system under seismic excitation was established and 104 GM samples were selected to evaluate the correlation between 16 different IMs and train running safety over HSR bridges during earthquakes. The results show that spectral velocity (SvT1) and displacement (SdT1) at the fundamental period of the structure have good correlation with train running safety for mediumand long-period HSR bridges, and velocity spectrum intensity (VSI) and Housner intensity (HI) have good correlation for a wide range of structural periods. Overall, VSI and HI are the optimal IMs for safety analysis of trains running over HSR bridges during earthquakes. Finally, based on VSI and HI, the IM thresholds of an HSR bridge at different speed were analyzed.

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