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      • SCIESCOPUS

        Determination of spalling strength of rock by incident waveform

        Tao, Ming,Zhao, Huatao,Li, Xibing,Ma, Jialu,Du, Kun,Xie, Xiaofeng Techno-Press 2017 Geomechanics & engineering Vol.12 No.1

        An experimental technique for determining the spalling strength of rock-like materials under a high strain rate is developed. It is observed that the spalling strength of a specimen can be determined by only knowing the wavelength, loading peak value and length of the first spallation of an incident wave under a specific loading waveform. Using this method in combination with a split-Hopkinson pressure bar (SHPB) and other experimental devices, the spalling strength of granite specimens under a high strain rate is tested. Comparisons with other experimental results show that the new measuring method can accurately calculate the dynamic tensile strength of rock materials under a high strain rate.

      • SCIESCOPUSKCI등재

        Antecedents of self-reported safety behaviors among commissioning workers in nuclear power plants: The roles of demographics, personality traits and safety attitudes

        Tao, Da,Liu, Zhaopeng,Diao, Xiaofeng,Tan, Haibo,Qu, Xingda,Zhang, Tingru Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.5

        Demographics, personality traits and attitudes are related to safety behaviors in varied workplaces, but their roles in nuclear power plants (NPPs) have not been fully understood. This study was conducted to explore the roles of a set of demographic, personality and attitudinal factors on self-reported safety behaviors (including safety participation and human errors) among NPP commissioning workers. Survey data were collected from 157 Chinese commissioning workers. Results showed that age and work experience were significantly associated with human errors, but not with safety participation. Neuroticism and conscientiousness were significantly related to human errors, while neuroticism, conscientiousness and agreeableness were significantly related to safety participation. Attitude towards questioning was observed as an antecedent of safety participation, and functioned as a mediating variable in the relation between conscientiousness and safety behaviors. The findings provide evidence-based implications on the design of diverse interventions and strategies for the promotion of safety behaviors in NPPs.

      • KCI등재

        Physical properties of tetragonal transition-metal borides Nb2MB2 (M = Mo, W, Re or Os) with a new superstructure

        Xiaofeng Li,Yaping Tao,Ziyu Hu,Shengli Zhang 한국물리학회 2015 Current Applied Physics Vol.15 No.9

        The mechanical and thermodynamic properties, chemical bonding characteristics and electronic structure of Nb2MB2 (M = Mo, W, Re or Os) with a new tetragonal U3Si2-type superstructure (space group P4/ mnc, no. 128) were studied by means of density functional theory calculations. All Nb2MB2 structures studied were demonstrated to be thermodynamically and mechanically stable. The bulk, shear and Young's moduli, Poisson's ratio, Debye temperature and anisotropy factors were derived for ideal polycrystalline Nb2MB2 aggregates. Among these compounds, Nb2WB2 was found to have the highest shear modulus and hardness. The electronic densities of state and electronic localization function analysis revealed the metallicity and strong covalent BeB, NbeB and MB bonding in Nb2MB2. Moreover, these results reveal that the covalence between Nb 4d, M nd (n = 4 for Mo and 5 for W, Re and Os) and B 2p states is the cause of the relatively higher elastic modulus and hardness of the Nb-based compounds. Finally, thermodynamic properties, including the bulk modulus, heat capacity and thermal expansion coefficient of Nb2WB2 were obtained systematically under high temperature and pressure.

      • KCI등재

        Dynamic CT Myocardial Perfusion Imaging in Patients without Obstructive Coronary Artery Disease: Quantification of Myocardial Blood Flow according to Varied Heart Rate Increments after Stress

        Yu Lihua,Tao Xiaofeng,Dai Xu,Liu Ting,Zhang Jiayin 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.1

        Objective: The present study aimed to investigate the association between myocardial blood flow (MBF) quantified by dynamic CT myocardial perfusion imaging (CT-MPI) and the increments in heart rate (HR) after stress in patients without obstructive coronary artery disease. Materials and Methods: We retrospectively included 204 subjects who underwent both dynamic CT-MPI and coronary CT angiography (CCTA). Patients with more than minimal coronary stenosis (diameter ≥ 25%), history of myocardial infarction/ revascularization, cardiomyopathy, and microvascular dysfunction were excluded. Global MBF at stress was measured using hybrid deconvolution and maximum slope model. Furthermore, the HR increments after stress were recorded. Results: The median radiation dose of dynamic CT-MPI plus CCTA was 5.5 (4.5–6.8) mSv. The median global MBF of all subjects was 156.4 (139.8–180.4) mL/100 mL/min. In subjects with HR increment between 10 to 19 beats per minute (bpm), the global MBF was significantly lower than that of subjects with increment between 20 to 29 bpm (153.3 mL/100 mL/min vs. 171.3 mL/100 mL/min, p = 0.027). This difference became insignificant when the HR increment further increased to ≥ 30 bpm. Conclusion: The global MBF value was associated with the extent of increase in HR after stress. Significantly higher global MBF was seen in subjects with HR increment of ≥ 20 bpm.

      • KCI등재

        China FuTURE 4G TDD System: TD-SCDMA Evolution

        Xu Xiaodong,Tao Xiaofeng,Zhang Ping 에스케이텔레콤 (주) 2009 Telecommunications Review Vol.19 No.3

        Meeting with the evolution requirements from 3G to 4G system, FuTURE project and FuTURE 4G TDD system are introduced in detail, including the features, the key technologies related with the cellular architecture, physical layer and the implementation of trial system. It has been proved by the field tests that the FuTURE TDD system that can achieve the peak data rate of 122Mbps, where many enhanced technologies comparing with TD-SCDMA are adopted, including the Generalized Distributed Network Architecture, Soft Fractional Frequency Reuse and Fast Cell Group Selection. Moreover, some technologies proposed in the research and development of FuTURE TDD system have been accepted by 3GPP and become the candidate standards of the Enhanced 3G systems. At last, Gbps TDD system is now under researching and developing in China aiming with ITU IMT-Advanced (4G) system.

      • KCI등재

        Uncertainty Analysis of Dynamic Thermal Rating of Overhead Transmission Line

        Xing Zhou,Yanling Wang,Xiaofeng Zhou,Weihua Tao,Zhiqiang Niu,Ailing Qu 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.2

        Dynamic thermal rating of the overhead transmission lines is affected by many uncertain factors. The ambienttemperature, wind speed and wind direction are the main sources of uncertainty. Measurement uncertainty isan important parameter to evaluate the reliability of measurement results. This paper presents the uncertaintyanalysis based on Monte Carlo. On the basis of establishing the mathematical model and setting the probabilitydensity function of the input parameter value, the probability density function of the output value is determinedby probability distribution random sampling. Through the calculation and analysis of the transient thermalbalance equation and the steady- state thermal balance equation, the steady-state current carrying capacity, thetransient current carrying capacity, the standard uncertainty and the probability distribution of the minimumand maximum values of the conductor under 95% confidence interval are obtained. The simulation resultsindicate that Monte Carlo method can decrease the computational complexity, speed up the calculation, andincrease the validity and reliability of the uncertainty evaluation.

      • KCI등재

        Clustering Strategy Based on Graph Method and Power Control for Frequency Resource Management in Femtocell and Macrocell Overlaid System

        Hongjia Li,Xiaodong Xu,Dan Hu,Xiaofeng Tao,Ping Zhang,Song Ci,Hui Tang 한국통신학회 2011 Journal of communications and networks Vol.13 No.6

        In order to control interference and improve spectrumef-ficiency in the femtocell and macrocell overlaid system (FMOS), we propose a joint frequency bandwidth dynamic division, clustering and power control algorithm (JFCPA) for orthogonal-frequencydivision-multiple access-based downlink FMOS. The overall system bandwidth is divided into three bands, and the macro-cellular coverage is divided into two areas according to the intensity of the interference from the macro base station to the femtocells, which are dynamically determined by using the JFCPA. A cluster is taken as the unit for frequency reuse among femtocells. We map the problem of clustering to the MAX k-CUT problem with the aim of eliminating the inter-femtocell collision interference, which is solved by a graph-based heuristic algorithm. Frequency bandwidth sharing or splitting between the femtocell tier and the macrocell tier is determined by a step-migration-algorithm-based power control. Simulations conducted to demonstrate the effectiveness of our proposed algorithm showed the frequency-reuse probability of the FMOS reuse band above 97.6% and at least 70% of the frequency bandwidth available for the macrocell tier, which means that the co-tier and the cross-tier interference were effectively controlled. Thus, high spectrum efficiency was achieved. The simulation results also clarified that the planning of frequency resource allocation in FMOS should take into account both the spatial density of femtocells and the interference suffered by them. Statistical results from our simulations also provide guidelines for actual FMOS planning.

      • SCOPUSKCI등재

        Uncertainty Analysis of Dynamic Thermal Rating of Overhead Transmission Line

        Zhou, Xing,Wang, Yanling,Zhou, Xiaofeng,Tao, Weihua,Niu, Zhiqiang,Qu, Ailing Korea Information Processing Society 2019 Journal of information processing systems Vol.15 No.2

        Dynamic thermal rating of the overhead transmission lines is affected by many uncertain factors. The ambient temperature, wind speed and wind direction are the main sources of uncertainty. Measurement uncertainty is an important parameter to evaluate the reliability of measurement results. This paper presents the uncertainty analysis based on Monte Carlo. On the basis of establishing the mathematical model and setting the probability density function of the input parameter value, the probability density function of the output value is determined by probability distribution random sampling. Through the calculation and analysis of the transient thermal balance equation and the steady- state thermal balance equation, the steady-state current carrying capacity, the transient current carrying capacity, the standard uncertainty and the probability distribution of the minimum and maximum values of the conductor under 95% confidence interval are obtained. The simulation results indicate that Monte Carlo method can decrease the computational complexity, speed up the calculation, and increase the validity and reliability of the uncertainty evaluation.

      • SCIESCOPUSKCI등재

        Clustering Strategy Based on Graph Method and Power Control for Frequency Resource Management in Femtocell and Macrocell Overlaid System

        Li, Hongjia,Xu, Xiaodong,Hu, Dan,Tao, Xiaofeng,Zhang, Ping,Ci, Song,Tang, Hui The Korea Institute of Information and Commucation 2011 Journal of communications and networks Vol.13 No.6

        In order to control interference and improve spectrum efficiency in the femtocell and macrocell overlaid system (FMOS), we propose a joint frequency bandwidth dynamic division, clustering and power control algorithm (JFCPA) for orthogonal-frequency-division-multiple access-based downlink FMOS. The overall system bandwidth is divided into three bands, and the macro-cellular coverage is divided into two areas according to the intensity of the interference from the macro base station to the femtocells, which are dynamically determined by using the JFCPA. A cluster is taken as the unit for frequency reuse among femtocells. We map the problem of clustering to the MAX k-CUT problem with the aim of eliminating the inter-femtocell collision interference, which is solved by a graph-based heuristic algorithm. Frequency bandwidth sharing or splitting between the femtocell tier and the macrocell tier is determined by a step-migration-algorithm-based power control. Simulations conducted to demonstrate the effectiveness of our proposed algorithm showed the frequency-reuse probability of the FMOS reuse band above 97.6% and at least 70% of the frequency bandwidth available for the macrocell tier, which means that the co-tier and the cross-tier interference were effectively controlled. Thus, high spectrum efficiency was achieved. The simulation results also clarified that the planning of frequency resource allocation in FMOS should take into account both the spatial density of femtocells and the interference suffered by them. Statistical results from our simulations also provide guidelines for actual FMOS planning.

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