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DC-DC converter current measurement for MPPT control
Noriyuki Kimura,Yoshinori Sakoda,Toshimitsu Morizane 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents the possibility to use the MOS-FET as the current measuring resistance. The shunt resistance is often used to measure the current in power electronics circuit since it is low cost and high reliable. However the reduction of components is always desirable for reduction of the cost and high reliability. Maximum power point tracking is indispensable for the renewable energy source, though the precise measurement of the power is not necessary. So the authors propose to use the MOS-FET switching device installed in the dc-dc converter circuit as the current measuring resistance. Simulation and experimental results of the first stage investigation are shown.
Imbalanced Fault Detection using Real Time Symmetrical Coordinate Calculation with Memorized Data
Noriyuki Kimura,Xiao-xiao Yu,Koji Niijima,Toshimitsu Morizane,Hideki Omori 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
This paper proposes a real time symmetrical coordinate transformation applied for detection of imbalanced fault in utility power system. The power conditioner of the photovoltaic system in Japan is required to remain connected when the utility power system fault occurs under certain condition. The most popular fault is 1 line-to-ground fault. The next is 2 line-short fault. Both cause the imbalance voltages and currents in 3-phase power system. To optimize the output from the power conditioner of the photovoltaic system, the detection of the imbalanced condition is important factor. In this paper, new development of the signal processing method by using the complex number algebra in real time system is shown. The fast detection of the imbalanced condition is verified by the computer simulations.
Reduction of Circulating Current of Double Converter Configuration for Additional Regeneration
Noriyuki Kimura,Toshimitsu Morizane,Yasuyuki Nishida 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents the analysis and solution about the circulating current appeared in the double converter configuration used to add the regenerative ability for a conventional diode rectifier.
Butter Tolerance in Children Allergic to Cow’s Milk
Noriyuki Yanagida,Takanori Minoura,Setsuko Kitaoka 대한천식알레르기학회 2015 Allergy, Asthma & Immunology Research Vol.7 No.2
We performed an oral food challenge (OFC) with 10 g of butter (equivalent of 2.9 mL cow’s milk) and 25-mL heated cow’s milk for 68 children with cow’s milk-allergy. Thirty-eight children reacted only to heated cow’s milk. Twenty-four children reacted to neither heated milk nor butter. Thirty-eight (86.4%) of 44 patients with positive results to the OFC for heated milk could safely tolerate butter. It is highly likely that even children with cow’s milk-allergy who show positive results to an OFC for heated milk can consume butter. The milk-specific IgE value indicative of a negative predictive value of over 95% was 17.8 kUA/L, and patients with low milk-specific IgE values may be able to safely consume butter. Including butter in the diets of patients with milk-allergy after a butter challenge may improve quality of life.
Effect of Number of Measurement Points on Accuracy of Muscle T2 Calculations
Noriyuki Tawara,Atsushi Nishiyama 대한자기공명의과학회 2016 Investigative Magnetic Resonance Imaging Vol.20 No.4
Purpose: The purpose of this study was to investigate the effect of the number of measurement points on the calculation of transverse relaxation time (T2) with a focus on muscle T2. Materials and Methods: This study assumed that muscle T2 was comprised of a single component. Two phantom types were measured, 1 each for long (“phantom”) and short T2 (“polyvinyl alcohol gel”). Right calf muscle T2 measurements were conducted in 9 healthy male volunteers using multiple-spin-echo magnetic resonance imaging. For phantoms and muscle (medial gastrocnemius), 5 regions of interests were selected. All region of interest values were expressed as the mean ± standard deviation. The T2 effective signal-ratio characteristics were used as an index to evaluate the magnetic resonance image quality for the calculation of T2 from T2- weighted images. The T2 accuracy was evaluated to determine the T2 reproducibility and the goodness-of-fit from the probability Q. Results: For the phantom and polyvinyl alcohol gel, the standard deviation of the magnetic resonance image signal at each echo time was narrow and monoexponential, which caused large variations in the muscle T2 decay curves. The T2 effective signal-ratio change varied with T2, with the greatest decreases apparent for a short T2. There were no significant differences in T2 reproducibility when > 3 measurement points were used. There were no significant differences in goodnessof- fit when > 6 measurement points were used. Although the measurement point evaluations were stable when > 3 measurement points were used, calculation of T2 using 4 measurement points had the highest accuracy according to the goodnessof- fit. Even if the number of measurement points was increased, there was little improvement in the probability Q. Conclusion: Four measurement points gave excellent reproducibility and goodnessof- fit when muscle T2 was considered mono-exponential.