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A Basic Study on Chip Size Determination of MOSFETs to Minimize Total Power Loss
Y. Ikegami,H. Obara,Y. Sato 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
Chip area of power semiconductor devices is one of the key parameters to realize highly-efficient converters. In the case of MOSFETs, a larger chip area results in lower on-state resistance. However, switching loss and gate drive loss may become dominant due to increase in parasitic capacitances when the chip area is too large. Thus, the chip area must be determined adequately considering given operating conditions and characteristics of the devices. In this paper, relationship between the chip area and loss reduction effect in three different types of MOSFETs, that is, silicon MOSFETs, silicon-carbide MOSFETs, and super-junction MOSFETs, is investigated experimentally. From the results, it is clarified that each MOSFET has the optimum points of the chip area for the loss reduction depending on the switching frequency and current. A determination criterion of the optimum chip area is discussed on the basis of the theoretical calculation of the losses.
The Manipulation of Milk Secretion in Lactating Dairy Cows - Review -
Rose, M.T.,Obara, Y. Asian Australasian Association of Animal Productio 2000 Animal Bioscience Vol.13 No.2
A number of developments have occurred over recent years that are being used commercially or have the potential to increase the milk yield and consequently the efficiency of dairy cows. Bovine growth hormone is the most widely known of several attempts that have been made to alter the metabolic endocrinology of dairy cows to increase the rate of milk secretion. The factors affecting the milk yield response to growth hormone, growth hormone-releasing factor, thyroxine and placental lactogen as well as to the immuno-neutralization of somatostatin are briefly considered. Secondly, the recent greater understanding of the mechanism by which the milk yield is increased following more frequent milking, which has resulted from the identification and characterization of the feedback inhibitor of lactation (FIL) protein, is reviewed. The identification of this protein provides new avenues of research which may lead to a reduction in the rate of decline in milk yield with advancing lactation or to undiminished milk yields despite a reduction in frequency with which the animals are milked.
Rose, M.T.,Obara, Y.,Fuse, H.,Hodate, K. Asian Australasian Association of Animal Productio 1996 Animal Bioscience Vol.9 No.1
Four castrated Corriedale sheep were used in an experiment to observe the changes in insulin, growth hormone and cortisol in blood plasma following a prolonged infusion of a high rate of somatostatin (SRIF). The animals wee infused with either saline, 25 or $50{\mu}g/kg/h$ of SRIF for 3 hours. Blood samples wee taken every 20 minutes until 1 hour following the end of the SRIF infusion. Both SRIF infusion levels suppressed the release of insulin into plasma to approximately 3.5 mU/l. The SRIF infusions reduced the concentration of growth hormone to barely detectable levels. Following the withdrawal of SRIF there was a massive release of growth hormone. The plasma concentration of growth hormone reached 60 ng/ml within 20 minutes, the length of the growth hormone discharge was in excess of 1 hour. The extent of the discharge of growth hormone following the SRIF infusions was greater than that suppressed by the infusion. The SRIF apparently caused an increase in the plasma concentration of cortisol at the end of the infusion and following is withdrawal. This is possibly associated with some change in the metabolic rate associated with the suppression of insulin or glucagons release. The present experiment demonstrates that a high rate of SRIF infusion can not completely inhibit the release of insulin into the plasma.