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      • KCI등재
      • KCI등재

        In Situ Synthesis and Strengthening of Powder Metallurgy High Speed Steel in Addition of LaB6

        Weijun Shen,Linping Yu,Zhi Li,Yuehui He,Qiankun Zhang,Huibin Zhang,Yao Jiang,Nan Lin 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.6

        A novel technology which was characterized by the vacuum solid state sintering was developed for powder metallurgyhigh speed steels production. During sintering, both the WC and Mo2C reacted with Fe and transformed toW and Mo rich M6C carbides which were the common hard phases in high speed steels. Also, a high number of W,Mo and Fe were dissolved in VC, forming the MC carbides. The densification of the material mainly relied on thesolubility effect during the M6C and MC carbides formation. By alloying with a 0.1 wt% of LaB6 to the steel, thebending strength and the fracture toughness were improved from 3290 MPa and 25.6 MPam1/2to 4018 MPa and29.4 MPam1/2, respectively. The TEM analysis demonstrated three types of reaction products by the LaB6 addition:the amorphous phase, the core-shell structure and the La2O3 phase. The impurity elements such as the Mg, Al,Si, S, Ca, and O were absorbed following the LaB6 addition. Moreover, the deoxidization effect caused by the LaB6addition promoted the sintering at a high-temperature period which contributed to the bending strength and fracturetoughness improvement.

      • An Approximation Scheme for Optimal Multicast Routing with Multiple QoS Constrains

        Weijun Yang,Yun Zhang 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.9

        This paper studies the problem of optimal multicast routing with multiple Quality-of- Service (QoS) constrains (OMRMC), which is regarded as a critical component in networks. However, it is not very efficient and effective for the existing algorithms. An undirected and connected graph G with m edges and n nodes is modeled to find a multicast routing tree from source to destination subset D in this paper, and a novel approximation algorithm called APP-OMRMC is proposed for OMRMC. The theoretical validations for the proposed method are presented to show its efficiency. After that, the different networks with different types of service are evaluated. Experimental results show that the proposed method APP-OMRMC is capable of finding the optimal (or minimum-cost) multicast routing tree with the approximation factor (1+ε) and time complexity of O(mτK-1).

      • Characteristics of Laser Aided Direct Metal Powder Deposition Process for Nickel-based Superalloy

        Zhang Kai,Liu Weijun,Shang Xiaofeng 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

        Laser additive direct deposition of metals is a new rapid manufacturing technology, which combines with computer aided design, laser cladding and rapid prototyping. The advanced technology can build fully-dense metal components directly from CAD files with neither mould nor tool. Based on the theory of this technology, a promising rapid manufacturing system called "Laser Metal Deposition Shaping (LMDS)" is being developed significantly. The microstructure and mechanical properties of the LMDS-formed samples are tested and analyzed synthetically. As a result, significant processing flexibility with the LMDS system over conventional processing capabilities is recognized, with potentially lower production cost, higher quality components, and shorter lead time.

      • KCI등재

        Evaluation of Salivary Gland Function Using Diffusion-Weighted Magnetic Resonance Imaging for Follow-Up of Radiation-Induced Xerostomia

        Yunyan Zhang,Dan Ou,Yajia Gu,Xiayun He,Weijun Peng 대한영상의학회 2018 Korean Journal of Radiology Vol.19 No.4

        Objective: To investigate the value of diffusion-weighted magnetic resonance imaging (DW-MRI) as a noninvasive tool to assess salivary gland function for follow-up of patients with radiation-induced xerostomia. Materials and Methods: This study included 23 patients with nasopharyngeal carcinoma who had been treated with parotidsparing radiotherapy (RT). Salivary function was assessed by DW-MRI pre-treatment and one week and one year post-RT, respectively. The maximum apparent diffusion coefficient (ADC) of parotid glands (pADCmax) and the time to peak ADC of parotid glands (pTmax) during stimulation were obtained. Multivariate analysis was used to analyze factors correlated with the severity of radiation-induced xerostomia. Results: The ADCs of parotid and submandibular glands (1.26 ± 0.10 x 10-3 mm2/s and 1.32 ± 0.07 x 10-3 mm2/s pre-RT, respectively) both showed an increase in all patients at one week post-RT (1.75 ± 0.16 x 10-3 mm2/s, p < 0.001 and 1.70 ± 0.16 x 10-3 mm2/s, p < 0.001, respectively), followed by a decrease in parotid glands at one year post-RT(1.57 ± 0.15 x 10-3 mm2/s, p < 0.001) but not in submandibular glands (1.69 ± 0.18 x 10-3 mm2/s, p = 0.581). An improvement in xerostomia was found in 13 patients at one year post-RT. Multivariate analysis revealed 4 significant predictors for the improvement of xerostomia, including dose to parotid glands (p = 0.009, odds ratio [OR] = 0.639), the ADC of submandibular glands (p = 0.013, OR = 3.295), pADCmax (p = 0.024, OR = 0.474), and pTmax (p = 0.017, OR = 0.729) at one week post-RT. Conclusion: The ADC value is a sensitive indicator for salivary gland dysfunction. DW-MRI is potentially useful for noninvasively predicting the severity of radiation-induced xerostomia.

      • Impromptu Service Discovery and Provision in Heterogeneous Assistive Environments

        Daqing Zhang,Weijun Qin,Brian Y. Lim,Manli Zhu 동국대학교 정보융합기술원 2008 International Journal of Assistive Robotics and Sy Vol.9 No.1

        Wireless hotspots are permeating the globe bringing interesting services and spontaneous connectivity to mobile users. In order to enable the elderly and disabled to be fully integrated into the society, it’s of paramount importance to build a pervasive assistive environment where assistive services can be automatically discovered and easily accessed with the device-tohand across the physical spaces. In this paper, we propose a framework that can support impromptu service discovery and context-aware service provision with mobile devices in heterogeneous smart assistive environments. Different from the existing approaches, the framework requires no specialized hardware or software installation in mobile client devices, and it can automatically discover and select appropriate services based on the user profile and situation context, and generate personalized user interfaces according to user preference and device capability. To demonstrate the effectiveness of the framework, we prototyped a set of assistive services in public spaces like shopping malls, leveraging the OSGi-based platform accessible from any WLAN enabled mobile devices.

      • Impromptu Service Discovery and Provision in Heterogeneous Assistive Environments

        Daqing Zhang,Weijun Qin,Brian Y. Lim,Manli Zhu 한국과학기술원 인간친화 복지 로봇 시스템 연구센터 2008 International Journal of Assistive Robotics and Me Vol.9 No.1

          Wireless hotspots are permeating the globe bringing interesting services and spontaneous connectivity to mobile users. In order to enable the elderly and disabled to be fully integrated into the society, it"s of paramount importance to build a pervasive assistive environment where assistive services can be automatically discovered and easily accessed with the device-to-hand across the physical spaces. In this paper, we propose a framework that can support impromptu service discovery and context-aware service provision with mobile devices in heterogeneous smart assistive environments. Different from the existing approaches, the framework requires no specialized hardware or software installation in mobile client devices, and it can automatically discover and select appropriate services based on the user profile and situation context, and generate personalized user interfaces according to user preference and device capability. To demonstrate the effectiveness of the framework, we prototyped a set of assistive services in public spaces like shopping malls, leveraging the OSGi-based platform accessible from any WLAN enabled mobile devices.

      • KCI등재후보

        Testing and finite element modeling of stressed skin diaphragms

        Qilin Zhang,Yang Liu,Weijun Qian 국제구조공학회 2007 Steel and Composite Structures, An International J Vol.7 No.1

        The cold formed light-gauge profiled steel sheeting can offer considerable shear resistance acting in the steel building frame. This paper conducted the full-scale test on the shear behavior of stressed skin diaphragm using profiled sheeting connected by the self-tapping screws. A three-dimensional finite element model that simulates the stressed skin diaphragm was developed. The sheet was modeled using thin element model while the supporting members were simulated using beam elements. Fasteners were represented in the numerical model as equivalent springs. A joint test program was conducted to characterize the properties of these springs and results were reported in this study. Finite element model of the full-scale test was analyzed by use of the ANSYS package, considering nonlinearity caused by the large deflection and slip of fasteners. The experimental data was compared with the results acquired by the EUR formulas and finite element analysis.

      • Research of high response control technology of a moving coil electromechanical converter

        Gong Zhang,Zheng Xu,Weijun Wang,Zhichen Hou,Xing Gu,Ning Lin,Liangwei Luo,Jing Huang 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

        Electromechanical converters (EMCs) are regarded as the most widely employed linear motion mechanism in various industry driving fields. This study tries to improve the characteristics deficiency of a moving coil electro-mechanical converter (MC-EMC), such as the output electromagnetic force, response time and response speed, and based on the time constant and currents are effected by inductance and resistance of the transformation coils, the carrying current coils of MC-EMC are adopted a transformation of segmentation and combination. The mathematical model and simulation for the response time, displacement, output electromagnetic force, acceleration of MC-EMC are proposed respectively. Results show that compared coils in parallel divided into three sections with coils in single group, the displacement step response time is reduced from 14.6㎳ to 9.94㎳ the response speed is over doubled, and electromagnetic force is raised about 8 times, the acceleration is increased by 8.7 times, the peak response time is reduced about 0.5 times, which means the design MC-EMC could realize the performance of short response time and high electromagnetic force, and display good prospects.

      • KCI등재

        Establishment and evaluation of a murine anb3-integrinexpressing cell line with increased susceptibility to Foot-and-mouth disease virus

        Wei Zhang,Kaiqi Lian,Fan Yang,Yang Yang,Zhijian Zhu,Zixiang Zhu,Weijun Cao,Ruoqing Mao,Ye Jin,Jijun He,Jianhong Guo,Xiangtao Liu,Haixue Zheng 대한수의학회 2015 Journal of Veterinary Science Vol.16 No.3

        Integrin anb3 plays a major role in various signaling pathways, cell apoptosis, and tumor angiogenesis. To examine the functions and rolesof anb3 integrin, a stable CHO-677 cell line expressing the murine anb3 heterodimer (designated as “CHO-677-manb3” cells) wasestablished using a highly efficient lentiviral-mediated gene transfer technique. Integrin subunits an and b3 were detected at the gene andprotein levels by polymerase chain reaction (PCR) and indirect immunofluorescent assay (IFA), respectively, in the CHO-677-manb3 cellline at the 20th passage, implying that these genes were successfully introduced into the CHO-677 cells and expressed stably. A plaque-formingassay, 50% tissue culture infective dose (TCID50), real-time quantitative reverse transcription-PCR, and IFA were used to detect the replicationlevels of Foot-and-mouth disease virus (FMDV) in the CHO-677-manb3 cell line. After infection with FMDV/O/ZK/93, the cell line showeda significant increase in viral RNA and protein compared with CHO-677 cells. These findings suggest that we successfully established a stableanb3-receptor-expressing cell line with increased susceptibility to FMDV. This cell line will be very useful for further investigation of anb3integrin, and as a cell model for FMDV research.

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