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Sulphonated Reduced Graphene Oxide: A High Performance Anode Material for Lithium Ion Battery
Haibo Li,Rui Niu,Sen Liang,Yulong Ma,Min Luo,Jin Li,Lijun He 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.4
In this work, the sulfonated reduced graphene oxide (SRGO) was synthesized and proposed as an enhanced anode material for lithium ion battery (LIB). The result shows that the SRGO has an improved battery performance (i.e., ~341.7 mAh/g and ~190.6 mAh/g corresponds to SRGO and RGO at the 100th cycle with a current density of 200 mA/g) and superior cycling stability compared with pristine reduced graphene oxide (RGO). These are attributed to the improved specific surface area (448.35 m2 /g) and conductivity (2.5 x 10-4 S/m). Further, the SRGO exhibits good rate capability and excellent energy density at various current densities ranging from 50 mAh/g to 2000 mAh/g, suggesting that SRGO could be a promising anode material for high capacity LIB.
Direct Duty-ratio Modulated Fault-tolerant Strategy for Matrix Converter-fed Motor Drives
Li, Yulong,Choi, Nam-Sup,Han, Byung-Moon,Nho, Eui-Cheol The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1
Direct duty-ratio PWM schemes for continuous fault tolerant operation of matrix converter-fed motor drives are presented. The proposed method features simple modular modulation structure based on per output phase concept, which requires no additional modification on the normal modulation schemes for fault-tolerant applications. Realizations of fault-tolerant strategy applied to different system configurations are also treated to enhance the system flexibility. The proposed method can be effectively applied to treat the motor open phase fault and converter switching device failure. Simulation and experimental results show the feasibility and validation of the proposed strategies.
Novel Direct Duty-Ratio Modulation Method for Matrix Converter
Yulong Li(리위롱),Nam-Sup Choi(최남섭),Byung-Moon Han(한병문) 전력전자학회 2008 전력전자학술대회 논문집 Vol.- No.-
A novel general direct duty ratio pulse width modulation strategy is proposed to modulate matrix converters. By using average concept over one switching period, the modulation algorithm and the required equations are derived to synthesize the desired output voltage and to achieve the controlled input power factor. The proposed method use continuous carrier and the predetermined duty ratio signal for directly generating gating signals an thus is named “direct duty ratio PWM(DDPWM)”.The feasibility and validity of the proposed strategy are verified by experimental results.
A Dynamic Interactive Pooling Based Human-Computer Interaction
Yulong Li,Yepeng Guan,Jinfeng Ma 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.8
Human-computer interaction (HCI) has great potential for applications in many fields. A HCI method has been developed based on audio-visual perceptive features and dynamic interactive pooling. A mode analysis based fusion strategy is proposed to fuse the interactive responses from audio-visual modalities especially for the case there are deviations from the modalities at the same time. The developed approach can be applied with a better performance even in single modal with multiple interactive users in the scenario. The users in the scenario are endowed with a fair chance to perform HCI by their interactive priorities no matter how many modalities used, and the interactive authority and priority are updated dynamically according to the variation of HCI content. The scenario and multiple users altogether are regarded as a dynamic HCI pooling. The diversity of interactive habits among multiple users is considered in an ordinary hardware from a crowded scene without any hypothesis for the scenario contents in advance. The pooling is updated dynamically to meet the user demands with the most intentions preferentially. Comparative study with state-of-the-arts has indicated the superior performance of the proposed method.
Yulong Li,Tao Wang,Xinyi Song,Guijun Li 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.1
Terrorist attacks on infrastructures are serious incidents in many countries. Measures to prevent terrorist attacks and minimize the damage are critical in the design of infrastructures. This paper develops an Analytic Hierarchy Process (AHP) based risk assessment model to identify the key components of the overpass bridge in terrorist attacks, and prioritizes a variety of possible attack means with multiple criteria. The AHP risk assessment model can be used to not only set the priority of protected components, but also to allocate resources to the most critical protecting methods within a limited budget. An interchange overpass bridge in Beijing, China is analysed to validate the model. The results show that the method is suitable for the optimal resource allocation in the process of the overpass bridge anti-terrorism design, the formulation of a defence strategy and the protection resource allocation scheme for the overpass bridge against a terrorist attack. The method can also be used for dynamic allocating the resources for the overpass bridge under the early warning of terrorist attacks.
DDPWM Based Control of Matrix Converters
Yulong Li,Nam-Sup Choi,Byung-Moon Han 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.4
In this paper, pulse-width modulation (PWM) control strategy of various topologies of matrix converters is presented, which is based on direct duty ratio PWM (DDPWM). Because the DDPWM method has the characteristics of the inherent per-phase modular structure, it can be effectively applied to single-phase, two-phase and three-phase four-leg matrix converters as well as the common three-phase to three-phase matrix converter. Also, this paper treats command generation method in each matrix converter. The feasibility and validity of the proposed method are verified by experimental results.
Novel Predictive Current Control Pulse Width Modulation Method for Matrix Converters
Yulong Li(리위룽),Nam-Sup Choi(최남섭),Byung-Moon Han(한병문),Seung-Chul Yang(양승철) 대한전기학회 2008 대한전기학회 학술대회 논문집 Vol.2008 No.11
A new pulse width modulation method based on predictive current control strategy is proposed to modulate matrix converters. The predictive current controller utilizes a discrete-time model to predict the future values of output currents and generates proper duty-ratios to minimize the output current errors. The proposed method uses continuous carrier and establishes a predictive current controller to predetermine duty ratio signal for directly generating gating signals an thus is named "predictive current control PWM(PCCPWM)". The modulation algorithm and the required equations are derived by using average concept over one switching period. Thus it can be easily extended to other matrix converter topologies, especially with neutral connections, such as sing le-phase and two-phase matrix converters. The feasibility and validity of the proposed strategy are verified by computer simulation and experimental results.
Fault-Tolerant Modulation Strategy with Direct Duty-Ratio PWM for Matrix Converter-Fed Motor Drives
Yulong Li,Nam-Sup Choi,Byung-Moon Han,Eui-Cheol Nho 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
Direct duty-ratio PWM schemes for continuous fault tolerant operation of matrix converter-fed motor drives are presented. The proposed method features simple modular modulation structure based on per output phase concept, which requires no additional modification on the normal modulation schemes for fault-tolerant applications. Realizations of fault-tolerant strategy applied to different system configurations are also treated to enhance the system flexibility. The proposed method can be effectively applied to treat the motor open phase fault and converter switching device failure. Simulation results will be provided to verify the feasibility and availability.
Direct Duty Ratio Pulse Width Modulation Method for Matrix Converters
Yulong Li,Nam-Sup Choi,Byung-Moon Han,Kyoung Min Kim,Buhm Lee,Jun-Hyub Park 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.5
This paper presents a new carrier based pulse-width modulation (PWM) method for matrix converters. By using the concept of average over one switching period, the modulation algorithm and the required equations are derived to synthesize the desired output voltage and to achieve the controlled input power factor. The proposed method uses a continuous carrier and the predetermined duty ratio signals to directly generate the gating signals and, thus, is referred to as "direct duty ratio PWM (DDPWM)". The feasibility and validity of the proposed method were verified by simulation and experiment.
Direct Duty-ratio Modulated Fault-tolerant Strategy for Matrix Converter-fed Motor Drives
Yulong Li,Nam-Sup Choi,Byung-Moon Han,Eui-Cheol Nho 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.1
Direct duty-ratio PWM schemes for continuous fault tolerant operation of matrix converter-fed motor drives are presented. The proposed method features simple modular modulation structure based on per output phase concept, which requires no additional modification on the normal modulation schemes for fault-tolerant applications. Realizations of fault-tolerant strategy applied to different system configurations are also treated to enhance the system flexibility. The proposed method can be effectively applied to treat the motor open phase fault and converter switching device failure. Simulation and experimental results show the feasibility and validation of the proposed strategies.