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      • KCI등재

        Natural History of Untreated Coronary Total Occlusions Revealed with Follow-Up Semi-Automated Quantitative Coronary CT Angiography: The Morphological Characteristics of Initial CT Predict Occlusion Shortening

        Qian Wu,Mengmeng Yu,Yuehua Li,Wenbin Li,Zhigang Lu,Meng Wei,Jing Yan,Jiayin Zhang 대한영상의학회 2018 Korean Journal of Radiology Vol.19 No.2

        Objective: To investigate the morphological changes of coronary chronic total occlusion (CTO) as determined by coronary computed tomography angiography (CCTA) follow-up using semi-automated quantitative analysis. Materials and Methods: Thirty patients with 31 CTO lesions confirmed by invasive coronary angiography and baseline/follow-up CCTA were retrospectively included. CTOs were quantitatively analyzed by a semi-automated coronary plaque analysis software (Coronary Plaque Analysis, version 2.0, Siemens) after manually determining the lesion border. Recanalized lumen was defined as the linear-like enhanced opacity traversing the non-opacified occluded segment. Other parameters, such as total occlusion length, total occlusion volume, volume with low attenuation component (< 30 Hounsfield unit [HU]), volume with middle to high attenuation component (30−190 HU) as well as the calcification volume, were also recorded. Results: Recanalized lumen was found within 48.4% (15/31) occlusions on the follow-up CCTA, compared to 45.2% (14/31) occlusions on the baseline CCTA. Eleven of 14 lesions (78.6%) with CT-visible recanalized lumen within CTOs had a shorter occlusion length on follow-up compared to only 3 of 17 lesions (17.6%) without CT-visible recanalized lumen (odds ratio, 17.1, p < 0.001). The percentage of low attenuation component of occlusions was smaller on follow-up CCTA compared to baseline value (18.1 ± 20.1% vs. 22.6 ± 19.6%, p = 0.033). Conclusion: Coronary computed tomography angiography enables non-invasive characterization of natural progression of untreated CTO lesions. Recanalized lumen within CTOs observed at baseline CCTA was associated with shortening of occlusion length on follow-up. Compared to their earlier stage, occlusions of later stage were presented with higher density of non-calcified components.

      • KCI등재

        Thermospheric Wind Observation and Simulation during the Nov 4, 2021 Geomagnetic Storm Event

        Qian Wu,Dong Lin,Wenbin Wang,William Ward 한국우주과학회 2022 Journal of Astronomy and Space Sciences Vol.39 No.3

        Thermospheric wind observations from high to mid latitudes are compared with the newly developed Multiscale Atmosphere Geospace Environment (MAGE) model for the Nov 3–4 geomagnetic storm. The observation and simulation comparison shows a very good agreement and is better at high latitudes in general. We were able to identify a thermospheric poleward wind reduction possibly linked to a northward turning of the Interplanetary Magnetic Field (IMF) at ~22 UT on Nov 3 and an enhancement of the poleward wind to a southward turning near 10 UT on Nov 4 at high latitudes. An IMF southward turning may have led to an enhancement of equatorward winds at Boulder, Colorado near midnight. Simultaneous occurrence of aurora may be associated with an IMF By turning negative. The MAGE model wind simulations are consistent with observations in these cases. The results show the model can be a very useful tool to further study the magnetosphere and ionosphere coupling on short time scales.

      • Thermospheric Wind Observation and Simulation during the Nov 4, 2021 Geomagnetic Storm Event

        Wu, Qian,Lin, Dong,Wang, Wenbin,Ward, William The Korean Space Science Society 2022 Journal of astronomy and space sciences Vol.39 No.3

        Thermospheric wind observations from high to mid latitudes are compared with the newly developed Multiscale Atmosphere Geospace Environment (MAGE) model for the Nov 3-4 geomagnetic storm. The observation and simulation comparison shows a very good agreement and is better at high latitudes in general. We were able to identify a thermospheric poleward wind reduction possibly linked to a northward turning of the Interplanetary Magnetic Field (IMF) at ~22 UT on Nov 3 and an enhancement of the poleward wind to a southward turning near 10 UT on Nov 4 at high latitudes. An IMF southward turning may have led to an enhancement of equatorward winds at Boulder, Colorado near midnight. Simultaneous occurrence of aurora may be associated with an IMF By turning negative. The MAGE model wind simulations are consistent with observations in these cases. The results show the model can be a very useful tool to further study the magnetosphere and ionosphere coupling on short time scales.

      • KCI등재

        In-Doped CdZnTe Crystal Growth under Controlled Te Partial Pressure

        Yongbiao Qian,Wenbin Sang,Gang Li,Jiahua Min,Zhubin Shi,Chenying Zhou 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

        In-doped CdZnTe (CZT) crystals have been investigated under controlled Te partial pressure. The dependence of the electrical properties on the In dopant concentration under fixed Te partial pressure and the dependence on Te partial pressure under fixed In dopant concentration are presented. The optimized growth parameters, such as Te partial pressure, In dopant concentration, etc., were obtained for preparing In-doped CZT crystal of high resistivity up to 1010 cm. In addition, based on an In-doped compensation mechanism in CZT crystals is discussed.

      • KCI등재

        Passivation Layer of CdZnTe as Studied by Spectroscopic Ellipsometry

        Jianyong Teng,Wenbin Sang,Yue Lu,Yanyan Lou,Jiahua Min,Xiaoyan Liang,Kaifeng Qin,Yongbiao Qian 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

        An oxidized layer was obtained on a cadmium zinc telluride (CZT) wafer by using chemical etching first in a KOH-KCl solution and then in an NH4F/H2O2 solution. The oxidized layer on the CZT obtained by using this method was analyzed by using ex-situ spectroscopic ellipsometry (SE) for the first time. In particular, the optical constants and the thickness of the chemical oxidized layer were obtained as functions of the oxidizing time.

      • KCI등재

        In uence of In dopant on PL Spectra of CdZnTe Crystals

        Jianyong Teng,Wenbin Sang,Gang Li,Zhubin Shi,Jiahua Min,Dongni Hu,Yongbiao Qian 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.1

        Photoluminescence (PL) spectra are used to characterize the high resistivity of an In-doped CdZnTe (CZT) crystal. The features of the PL spectra vary with changing In-dopant concentration, indicating that the In-dopant concentration has a great impact on the defect type and density and on the extent of compensation in the In-doped CZT crystal. With the addition of In donors, a new sharp neutral donor bound exciton [D0, X] peak at 1.65 eV, corresponding to In substituting defect (In+ Cd) and a new defect complex band centered at 1.505 eV, related to the singly negative complex (VCd-InCd)- are observed. Meanwhile, the intensity and position of the feature peaks in PL spectra vary with the change of the In dopant concentration, representing the changes of the defect type and density and the extent of compensation in the crystal. It conrms that the Cd vacancy or residual impurity acceptors are dominantly compensated by In donors. The measured conduction type and carrier densities are the results of compensation between Cd vacancies and In donors and Te antisites, which are related to the In-dopant concentration and the stoichiometry for the CZT crystal. Photoluminescence (PL) spectra are used to characterize the high resistivity of an In-doped CdZnTe (CZT) crystal. The features of the PL spectra vary with changing In-dopant concentration, indicating that the In-dopant concentration has a great impact on the defect type and density and on the extent of compensation in the In-doped CZT crystal. With the addition of In donors, a new sharp neutral donor bound exciton [D0, X] peak at 1.65 eV, corresponding to In substituting defect (In+ Cd) and a new defect complex band centered at 1.505 eV, related to the singly negative complex (VCd-InCd)- are observed. Meanwhile, the intensity and position of the feature peaks in PL spectra vary with the change of the In dopant concentration, representing the changes of the defect type and density and the extent of compensation in the crystal. It conrms that the Cd vacancy or residual impurity acceptors are dominantly compensated by In donors. The measured conduction type and carrier densities are the results of compensation between Cd vacancies and In donors and Te antisites, which are related to the In-dopant concentration and the stoichiometry for the CZT crystal.

      • Internet Immunization Strategy based on Relations of Nodes

        Fan Tongrang,Qin Wanting,Zhao Wenbin,Wang Qian,Yu Tao 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.11

        Inspired by the biological immune system against outside invasion in nature, this paper propose a network security strategy using Agent technology. The Agents with independent behavior capacity are set for resisting network intrusion using their spontaneous coordinate organization. Based on the comparisons of existing immunization strategies, such as target immune, acquaintance immune and random immunity, it is found that the importance of nodes in network are influenced by interaction between nodes, degree of nodes, information flow, and other factors. If the nodes are more important, they have a greater influence over the whole network. When important nodes are infected by virus, there will be a higher probability of spreading of hazard information. Therefore, this paper proposes a network security model using Agent technology, where important nodes are implanted with relationship immunization strategy. Experimental results show when the network suffered from random or malicious attacks, relationship immunization strategy is more effective than others existing methods.

      • KCI등재

        Performance study of g-C3N4/carbon black/BiOBr@Ti3C2/MoS2 photocatalytic fuel cell for the synergistic degradation of different types of pollutants

        Guo Huilin,Yu Tingting,Zhao Lei,Qian Jun,Yu Jiahe,Zhang Yu,Teng Yongyue,Zhu Chunshui,Yang Tao,Chen Wenbin,Gong Picheng,Jiang Cuishuang,Gao Changfei,Yang Bing,Yang Chenyu 한국탄소학회 2023 Carbon Letters Vol.33 No.3

        In this study, a bipolar visible light responsive photocatalytic fuel cell (PFC) was constructed by loading a Z-scheme g-C3N4/carbon black/BiOBr and a Ti3C2/MoS2 Schottky heterojunction on the carbon brush to prepare the photoanode and photocathode, respectively. It greatly improved the electron transfer and achieved efficient degradation of organic pollutants such as antibiotics and dyes simultaneously in two chambers of the PFC system. The Z-scheme g-C3N4/carbon black/BiOBr formed by adding highly conductive carbon black to g-C3N4/BiOBr not only effectively separates the photogenerated carriers, but also simultaneously retains the high reduction of the conduction band of g-C3N4 and the high oxidation of the valence band of BiOBr, improving the photocatalytic performance. The exceptional performance of Ti3C2/MoS2 Schottky heterojunction originated from the superior electrical conductivity of Ti3C2 MXene, which facilitated the separation of photogenerated electron–hole pairs. Meanwhile, the synergistic effect of the two photoelectrodes further improved the photocatalytic performance of the PFC system, with degradation rates of 90.9% and 99.9% for 50 mg L−1 tetracycline hydrochloride (TCH) and 50 mg L−1 rhodamine-B (RhB), respectively, within 180 min. In addition, it was found that the PFC also exhibited excellent pollutant degradation rates under dark conditions (79.7%, TCH and 97.9%, RhB). This novel pollutant degradation system is expected to provide a new idea for efficient degradation of multiple pollutant simultaneously even in the dark.

      • KCI등재

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