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Hwu, K.I.,Jiang, W.Z.,Chen, H.M. The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.4
In this paper, an improved KY converter is presented, which is constructed mainly by one charge pump capacitor and one central-tapped coupling inductor. Besides, a passive clamping snubber is added to this converter to improve the efficiency above half load. As compared to the KY converter, the voltage conversion ratio of the proposed converter is upgraded significantly. In this paper, the basic operating principles and mathematical deductions of the proposed converter are described, along with some experimental results provided to demonstrate the feasibility and effectiveness of the proposed converter.
High Step-Up Converter with Hybrid Structure Based on One Switch
K. I. Hwu,T. J. Peng 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.4
A novel high step-up converter is presented herein, which combines the conventional buck-boost converter, the charge pump capacitor and the coupling inductor. By doing so, a quite high voltage conversion ratio due to not only the turns ratio but also the duty cycle, so as to increase design feasibility. It is noted that the denominator of the voltage conversion ratio is the square of one minus duty cycle. Above all, there is no voltage spike across the switch due to the leakage inductance and hence no passive or active snubber is needed, and furthermore, the used switch is driven without isolation and hence the gate driving circuit is relatively simple, thereby upgrading the industrial application capability of this converter. In this paper, the basic operating principles and the associated mathematical deductions are firstly described in detail, and finally some experimental results are provided to demonstrate the effectiveness of the proposed high step-up converter.
A Novel Voltage-Boosting Converter with Leakage Inductance Energy Recycling
K. I. Hwu,W. Z. Jiang,L. C. Yang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In this paper a novel simple high step-up converter using a coupled inductor and a charge pump capacitor is presented. Compared with the traditional boost converter and other converters with simple structures, the proposed converter can achieve higher voltage gain. The leakage inductance energy of the coupled inductor can be recycled without any clamp circuit. Moreover, the active switch is not floating; thus, no isolated driver is required. Finally, the operating principles and the analysis of the proposed converter and an experimental prototype are given to provide the effectiveness of the proposed converter.
High Step-Up Converter with Hybrid Structure Based on One Switch
Hwu, K.I.,Peng, T.J. The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.4
A novel high step-up converter is presented herein, which combines the conventional buck-boost converter, the charge pump capacitor and the coupling inductor. By doing so, a quite high voltage conversion ratio due to not only the turns ratio but also the duty cycle, so as to increase design feasibility. It is noted that the denominator of the voltage conversion ratio is the square of one minus duty cycle. Above all, there is no voltage spike across the switch due to the leakage inductance and hence no passive or active snubber is needed, and furthermore, the used switch is driven without isolation and hence the gate driving circuit is relatively simple, thereby upgrading the industrial application capability of this converter. In this paper, the basic operating principles and the associated mathematical deductions are firstly described in detail, and finally some experimental results are provided to demonstrate the effectiveness of the proposed high step-up converter.
K. I. Hwu,W. Z. Jiang,H. M. Chen 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.4
In this paper, an improved KY converter is presented, which is constructed mainly by one charge pump capacitor and one central-tapped coupling inductor. Besides, a passive clamping snubber is added to this converter to improve the efficiency above half load. As compared to the KY converter, the voltage conversion ratio of the proposed converter is upgraded significantly. In this paper, the basic operating principles and mathematical deductions of the proposed converter are described, along with some experimental results provided to demonstrate the feasibility and effectiveness of the proposed converter.
Applying Multi-Oversampling to One-Comparator Counter-Based Sampling to Enhance System Stability
Y. T. Yau,K. I. Hwu,C. W. Wang,Jenn-Jong Shieh 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This paper presents a novel method to enhance the system stability of a digital controller for a switching power converter under one-comparator counter-based sampling based on higher sampling frequency. However, the sampling rate and the hardware are not changed. The measured results of the proposed strategy are presented to demonstrate this concept.
System Clock Reduction Based on Multiple Sampling for Digital Switching Power Supplies
Y. T. Yau,K. I. Hwu,W. Z. Jiang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
In this paper, the proposed sampling structure based on one-comparator sampling is presented, which can significantly reduce the system clock frequency from 100MHz to 25MHz, so as to reduce chip area. This method is verified by a synchronously-rectified buck converter with a switching frequency of 200kHz, and the digital controller takes as a control kernel the EP1C3T100 FPGA created by Altera Co., along with the VHDL language to program this controller.
Phase contrast radiography of Lewy bodies in Parkinson disease
Koh, S.B.,Suh, S.I.,Lee, D.H.,Kim, A.R.,Oh, C.H.,Yoon, J.S.,Weon, B.M.,Seol, S.K.,Pyun, A.R.,Je, J.H.,Hwu, Y.,Margaritondo, G. Elsevier 2006 NeuroImage Vol.32 No.2
<P><B>Abstract</B></P><P>Parkinson's disease (PD), defined as a neurodegenerative disorder, is characterized by the loss of dopaminergic neurons and the presence of Lewy bodies in neurons. Morphological study of Lewy bodies is important to identify the causes and the processes of PD. Here, we investigate a possibility of phase contrast radiography using coherent synchrotron X-rays to explore the microscopic details of Lewy bodies in thick (∼3?mm) midbrain tissues. Autopsied midbrain tissues of a PD patient were sliced in 3?mm thickness and then examined using synchrotron X-rays from the 7B2 beamline of the Pohang Light Source. Refraction-enhanced phase contrast radiography and microtomography were adopted to identify dark core and dim edge of Lewy bodies in neurons. The morphology of Lewy bodies was clearly revealed by the phase contrast radiography in very thick (3?mm) midbrain tissues without any staining treatment. Three-dimensional volume rendered microtomography of the autopsied midbrain tissues demonstrates striking evidence that several Lewy bodies are agglomerated by dim edges in a neuron. We suggest that the phase contrast radiography could be a useful tool to morphologically investigate the causes or the processes in PD.</P>
Cock Spermatozoa Serve as the Gene Vector for Generation of ransgenic Chicken (Gallus gallus)
Yang, C.C.,Chang, H.S.,Lin, C.J.,Hsu, C.C.,Cheung, J.I.,Hwu, L.,Cheng, W.T.K. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.7
To evaluate the feasibility of using sperm-mediated gene transfer (SMGT) for carrying foreign gene into chicken oocyte, a reporter gene, CX-EGFP, was used in this study. The reporter gene was first mixed with liposome or liposome-like compound and the mixtures were further combined with ejaculated cock spermatozoa. The spermatozoa treated with liposome and CX-EGFP mixture was subsequently coincubated with DNaseI to remove the extra DNA which insured the authenticity of positive signals. The treated sperms were then subjected to transgene (reporter gene) existence analysis and artificial insemination of laying hens. Obtained results indicated that the spermatozoa were able to take-in the foreign DNA; which was confirmed by polymerase chain reaction and Southern blot analysis. In the following experiment, fresh ejaculated sperms were mixed with CX-EGFP-liposome or CX-EGFP-liposome-like complex then used for artificial insemination of each of six laying hens. Eggs laid between day-3 and day-7 post insemination were collected. Newly hatched chicks, two out of 53 from CX-EGFP/liposome treated group and two out of 21 from CXEGFP/liposome-like treated group, were proven to be transgenic. This study suggests that SMGT is a powerful method for generating transgenic chickens.
E-beam lithography and electrodeposition fabrication of thick nanostructured devices
Lo, T N,Chen, Y T,Chiu, C W,Liu, C J,Wu, S R,Lin, I K,Su, C I,Chang, W D,Hwu, Y,Shew, B Y,Chiang, C C,Je, J H,Margaritondo, G Institute of Physics [etc.] 2007 Journal of Physics. D, Applied Physics Vol.40 No.10
<P>A nanofabrication approach based on advanced e-beam lithography and electrodeposition successfully produced high-resolution (≈40 nm line width) metal structures with high aspect ratio (>12) and high density. The combination of these characteristics is essential for hard-x-ray optical components such as zone plates, for x-ray lithography masks and for other devices.</P>