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RISS 인기검색어
- 검색키워드
- 저자 : Shen Yunfeng (검색결과 6 건)
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Shen Yunfeng,Li Xiucun,Zhang Chao,Zhong Hai,Dou Weiqiang 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.8
Objective: To investigate the clinical application of differential subsampling with Cartesian ordering (DISCO) contrastenhanced (CE) magnetic resonance angiography for anterolateral thigh (ALT) flap transplantation, using operative findings as a reference. Materials and Methods: Thirty patients (21 males and nine females; mean age ± standard deviation, 45.5 ± 15.6 years) who were scheduled to undergo reconstruction with ALT flaps between June 2020 and June 2021 were included in the prospective study. Before ALT flap transplantation, patients were scanned using CE-DISCO imaging. All acquired DISCO images of the 60 lower limbs (both sides from each patient) were analyzed using maximum intensity projection and volume rendering methods. Two experienced radiologists were employed to examine the patterns of the lateral circumflex femoral artery (LCFA), its branches, and perforators and their skin termini, which were compared with the operative findings. Results: Using CE-DISCO, the patterns of the LCFA and its branches were clearly identified in all patients. Four different origins of the LCFA were found among the 60 blood vessels: type I (44/60, 73.3%), type II (6/60, 10.0%), type III (8/60, 13.3%), and type IV (2/60, 3.3%). Owing to a lack of perforators entering the skin, two patients did not undergo ALT flap transplantation. For the remaining 28 patients, the ALT flaps in 26 patients were successfully operated without flap reselection during the operation, while the remaining two patients underwent other surgical procedures due to the thin diameter of the perforator or injury of the perforator during the operation. The success rate of flap transplantation was 92.8% (26/28). All transplanted flaps exhibited good blood supply and achieved primary healing without infection or delayed healing. Conclusion: CE-DISCO imaging can be an effective method for preoperative perforator imaging before ALT flap transplantation.
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Chen Zhangyong,Shen Lanxiao,Liu YuLang,Wu Yunfeng 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2
In order to solve the problem of poor performance of traditional step-up/down converter, a novel converter with voltage gain neutral-point shifter is proposed in this paper. Compare to traditional buck-boost converter, only one series-capacitor is externally added. The coupling capacitor in proposed converter is series connected in charging power path, and therefore, the voltage stress of switches is reduced. Furthermore, when appropriately adjusting the duty cycle, half voltage stress of conventional buck-boost converter can be obtained. By using interleaved control strategy, the proposed converter has lower inductor current ripple and also has the character of higher step-down conversion ratio without any other auxiliary circuit. Moreover, the inherent current sharing character could be achieved when the duty cycle of main switch is less than 0.5. Based on these merits, the efficiency of the proposed converter can be improved. In this paper, the operational principle, the related analysis including inductor current ripple and voltage stress analysis, loss comparison analysis of the proposed converter are given. Finally, experimental prototype with 72 W is established to verify the character of the proposed converter.
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An Improved Interleaved Flyback Converter with Reduced Voltage Stress and Current Auto-sharing
Chen Zhangyong,Shen Lanxiao,Wu Yunfeng 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.4
The interleaved fl yback converters are widely used for the application of the renewable energy sources, electric vehicles, LED drivers et al. However, there are some challenges for this topology, such as leakage inductor energy of transformer, output current ripple, and high voltage stress of main switch. In order to solve the above problem existed in the converter, an improved interleaved fl yback converter with adding series capacitor is proposed in this paper. Through utilizing of active clamp technique for the converter, leakage inductor energy is observed and released, zero voltage switching of main switch are achieved. Furthermore, intrinsic current sharing of two phase fl yback converter could be automatic obtained without any voltage/current sensors by through charge balance for series capacitor existed in this converter topology. Thus, output current ripple is reduced and high effi ciency of interleaved fl yback converter is acquired. Comprehensive operational principle analysis and performance analysis are provided. Finally, a 60 W prototype is built to verify the analysis.
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SMGSA algorithm‑based MPPT control strategy
Yiping Xiao,Yunfeng Zhao,Zongtao Shen,Hongjian Jiao 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.5
Under partial shading conditions (PSCs), photovoltaic arrays exhibit power–voltage curves with multiple peaks. This phenomenon complicates the task of traditional maximum power point tracking (MPPT) algorithms, since they often converge to local maximum power points. To tackle this challenge, a novel MPPT control strategy, termed the slime mold golden sine algorithm (SMGSA), was introduced in this paper. This strategy adeptly identifies and tracks the global maximum power point. The efficacy of the SMGSA algorithm was assessed through six test functions from IEEE CEC 2020. A comparative analysis underscored its superior performance in both convergence speed and accuracy. A simulation model for MPPT was developed in MATLAB/Simulink. Within this model, various algorithms such as particle swarm optimization (PSO), tuna swarm optimization (TSO), slime mold algorithm (SMA), and SMGSA were examined. Comparative simulations revealed that the SMGSA-based MPPT strategy showcased expedited convergence speed and heightened accuracy under scenarios of uniform irradiance intensity, partial static shading, and dynamic shading. Consequently, the implementation of an SMGSAbased MPPT system can notably enhance the power generation efficiency of photovoltaic arrays under PSCs.
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Image Denoising Using Low-Rank and Sparse Constraints
Qiang Guo,Yunfeng Zhang,Xiaohong Shen (사)한국CDE학회 2013 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8
In this short paper, the SAIST method recently proposed for image denoising is improved by exploiting the fixed rank and sparsity constraints. Experimental results show that the improved SAIST obtains better performance than the original SAIST and BM3D.
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