http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Chen Yunfeng (검색결과 17 건)
- 무료
- 기관 내 무료
- 유료
-
Soft switching high step-down series-capacitor based converter with coupled-inductor technique
Chen, Zhangyong,Chen, Yong,Zhang, Chenyu,Wu, Yunfeng The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.4
High voltage step-down converters are very popular in distributed power systems, voltage regular modules, automatic vehicles, etc. To avoid extreme duty cycles, a series capacitor-based buck converter with a coupled inductor is proposed in this paper. In this converter, the voltage stresses of the power switches are clamped to half of the input voltage. Thus, low voltage rating MOSFETs with a low R<sub>ds,on</sub> could be utilized to improve the performance of the proposed converter. Moreover, synchronous MOSFETs are also used to reduce the conduction losses of the switches. Zero voltage switching (ZVS) for the main power switches is achieved using the coupled-inductor technique. In addition, through adding a bypass flowing path, a negative current is established to guarantee the ZVS condition of the power switches. The operating principle of the proposed converter is described in this paper, and the DC voltage gain ratio, automatic current sharing, soft switching condition and design guideline of the critical parameters are also given. Finally, experimental results obtained from a 60 V/200 W prototype are presented to verify the analysis of the proposed converter.
-
Yunfeng Zhang,Lele Chen,Yifan Cao,Si Chen,Chao Xu,Jun Xing,Kaiguang Zhang 대한위암학회 2020 Journal of gastric cancer Vol.20 No.2
Purpose: Globally, there is a high incidence of gastric cancer (GC). Leucine zipper-EF-hand containing transmembrane protein 1 (LETM1) is reported to play a vital role in several human malignancies. However, there is limited understanding of the role of LETM1 in GC. This study aims to investigate the effects of LETM1 on proliferation, migration, and invasion of GC cells. Materials and Methods: The expression levels of LETM1 in the normal gastric mucosal epithelial cells (GES-1) and GC cells were analyzed by quantitative real-time polymerase chain reaction and western blotting. CCK-8, wound healing, and Transwell invasion assays were performed to evaluate the effect of LETM1 knockdown or overexpression on the proliferation, migration, and invasion of the GC cells, respectively. Additionally, the effect of LETM1 knockdown or overexpression on GC cell apoptosis was determined by flow cytometry. Furthermore, the effect of LETM1 knockdown or overexpression on the expression levels of PI3K/Akt signaling pathway-related proteins was evaluated by western blotting. Results: The GC cells exhibited markedly higher mRNA and protein expression levels of LETM1 than the GES-1 cells. Additionally, the knockdown of LETM1 remarkably suppressed the GC cell proliferation, migration, and invasion, and promoted the apoptosis of GC cells, which were reversed upon LETM1 overexpression. Furthermore, the western blotting analysis indicated that LETM1 facilitates GC progression via the PI3K/Akt signaling pathway. Conclusions: LETM1 acts as an oncogenic gene to promote GC cell proliferation, migration, and invasion via the PI3K/Akt signaling pathway. Therefore, LETM1 may be a potential target for GC diagnosis and treatment.
-
-
Zhang, Yunfeng,Chen, Lele,Cao, Yifan,Chen, Si,Xu, Chao,Xing, Jun,Zhang, Kaiguang The Korean Gastric Cancer Association 2020 Journal of gastric cancer Vol.20 No.2
Purpose: Globally, there is a high incidence of gastric cancer (GC). Leucine zipper-EF-hand containing transmembrane protein 1 (LETM1) is reported to play a vital role in several human malignancies. However, there is limited understanding of the role of LETM1 in GC. This study aims to investigate the effects of LETM1 on proliferation, migration, and invasion of GC cells. Materials and Methods: The expression levels of LETM1 in the normal gastric mucosal epithelial cells (GES-1) and GC cells were analyzed by quantitative real-time polymerase chain reaction and western blotting. CCK-8, wound healing, and Transwell invasion assays were performed to evaluate the effect of LETM1 knockdown or overexpression on the proliferation, migration, and invasion of the GC cells, respectively. Additionally, the effect of LETM1 knockdown or overexpression on GC cell apoptosis was determined by flow cytometry. Furthermore, the effect of LETM1 knockdown or overexpression on the expression levels of PI3K/Akt signaling pathway-related proteins was evaluated by western blotting. Results: The GC cells exhibited markedly higher mRNA and protein expression levels of LETM1 than the GES-1 cells. Additionally, the knockdown of LETM1 remarkably suppressed the GC cell proliferation, migration, and invasion, and promoted the apoptosis of GC cells, which were reversed upon LETM1 overexpression. Furthermore, the western blotting analysis indicated that LETM1 facilitates GC progression via the PI3K/Akt signaling pathway. Conclusions: LETM1 acts as an oncogenic gene to promote GC cell proliferation, migration, and invasion via the PI3K/Akt signaling pathway. Therefore, LETM1 may be a potential target for GC diagnosis and treatment.
-
Chen Zhangyong,Zheng Zhanchao,Tang Xuan,Wu Yunfeng 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1
In this paper, combine hybrid modulation strategy and Model predictive control (MPC) for Dual active bridge (DAB) converter is presented to achieve high efciency of wide load range and fast dynamic response for bidirectional power fow conversion. Through ofine optimization of DAB converter at steady state, only one control variable is used to reduce computational burden, and without complex algorithm in the cost function for MPC strategy. In addition, based on the simpilifed average mode of DAB converter, diferent predictive currents are derived. Besides, three scenarios of smooth mode transition for the hybrid control strategy is given in detail. Thus, fast dynamic response for mode transition and high efciency for wide range is guaranteed by the proposed strategy. Finally, an experimental prototype of DAB converter is built and tested for verifying the steady state and fast transition with diferent operation modes performance.
-
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.
-
Microwave-assisted dissolution of UO2 with TBP-HNO3 complex
Yunfeng Zhao,Jing Chen 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.1
The direct dissolution of UO2 in TBP-HNO3 complex by microwave heating in this study suggests the possibility of dissolving spent nuclear fuels. This new technique offers many benefits for reduction in aqueous and organic waste generation and improved efficiency of chemical processing. The dissolution rate of UO2 particles with TBP-HNO3 complex by microwave assisted heating is highly dependent on the temperature and the particle size.
-
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.
-
Yunfeng Xiao,Lei Zeng,Zhenkun Cui,Siqian Jin,Yiguang Chen 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.1
The seismic performance of steel beam to concrete-encased composite column with unsymmetrical steel section joints is investigated and reported within this paper. Experimental and analytical evaluation were conducted on a total of 8 specimens with T-shaped and L-shaped steel section under lateral cyclic loading and axial compression. The test parameters included concrete strength, stirrup ratio and axial compression ratio. The response of the specimens was presented in terms of their hysterisis loop behavior, stress distribution, joint shear strength, and performance degradation. The experiment indicated good structural behavior and good seismic performance. In addition, a three-dimensional nonlinear finite-element analysis simulating was conducted to simulate their seismic behaviors. The finite-element analysis incorporated both bond-slip relationship and crack interface interaction between steel and concrete. The results were also compared with the test data, and the analytical prediction of joint shear strength was satisfactory for both joints with T-shaped and L-shaped steel section columns. The steel beam to concrete-encased composite column with unsymmetrical steel section joints can develop stable hysteretic response and large energy absorption capacity by providing enough stirrups and decreased spacing of transverse ties in column.
-
Microstructure design and energy transfer in Gd2(WO4)3: Yb3+/Er3+ phosphors
Wang Yunfeng,Chen Jun,Wei Xiaoyu,Cui Shaobo,Jia Xiao 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.78 No.9
Rare-earth-doped upconverison luminescent (UCL) materials have wide application prospects in the feld of nanoptoelectronics technology. However, achieving highly efficient UCL materials is still a big challenge due to the serious nonradiative energy loss in the host materials. In this research, Gd2(WO4)3: Yb3+, Er3+ inverse opal photonic crystals (IOPCs) were prepared using a polymethylmethacrylate (PMMA) template-assisted method, and the efects of modulations of the IOPC structure on UC emission properties of Er3+ were investigated systemically. As a result, the emission intensity of 2 H11/2- 4 I15/2 in IOPC was found to be suppressed 37.4%, and the radiative lifetimes of 4 S3/2- 4 I15/2 were prolonged 1.55 times. The effects of the doping concentration on the reciprocal of fluorescence lifetimes of 4 S3/2- 4 I15/2 between the IOPC and the reference (REF) samples showed that the cross-energy transfer (CET) rate and the electronic transition rate were greatly inhibited, which could be due to the effect of the modulation of the effective index on the radiative transition rate and on the decrease of nonradiative transition rate caused by periodic thin-walled structure of IOPC. The power-dependent UC emission properties validated the supposition that the IOPC structure could be effectively suppressed the local thermal effect and thermal quenching. This research presents a further step in the exploration of the new kind of UCL materials with high luminous efficiency.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
