http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
박경원(K.W. Park),김영철(Y.C. Kim),김준홍(J.H. Kim),서기영(K.Y. Su),고희석(H.S. Koh),이현우(H.W. Lee) 한국조명·전기설비학회 1997 한국조명·전기설비학회 학술대회논문집 Vol.1997 No.-
Power conversion system must be increased switching frequency in order to achieve a small size a light weight and a low noise. However, the switches of converter are subjected to high switching power losses and switching stresses. As a result of those, the power system brings on a low efficiency. In this paper, the authors propose a DC-DC boost converter of high power by partial resonant switch method (PRSM). The switching devices in a proposed circuit are operated with soft switching and the control technique of those is simplified for switch to drive in constant duty cycle. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. Also the circuit has a merit which is taken to increase of efficiency, as it makes to a regeneration at input source of accumulated energy in snubber condenser without loss of snubber in conventional circuit. The result is that the switching loss is very low and the efficiency of system is high. The proposed converter is deemed the most suitable for high power applications where the power switching devices are used.
Influence of Sr substitution on thermoelectric properties of La1−xSrxFeO3 ceramics
H.C. Wang,C.L. Wang,J.L. Zhang,W.B. Su,J. Liu,M.L. Zhao,N. Yin,Y.G. Lv,L.M. Mei 한국물리학회 2010 Current Applied Physics Vol.10 No.3
Perovskite La1-xSrxFeO3 (0.10 ≤ x ≤ 0.20) ceramics have been synthesized by the conventional solid-state reaction technique. Their electrical resistivity, Seebeck coefficient and thermal conductivity have been measured. It has been found that the increase of Sr content reduces significantly both the electrical resistivity and the Seebeck coefficient, but slightly increases the high-temperature thermal conductivity. An adiabatic hopping conduction mechanism of small polaron is suggested from the analysis of the temperature dependence of the electrical resistivity. Seebeck coefficients decrease with increasing temperature,and saturate at temperature above 573 K. The saturated value of Seebeck coefficient decreases with increasing of Sr contents, from 200 μV/K for x = 0.10 to 100 μV/K for x = 0.20. All samples exhibit lower thermal conductivity with values around 2.6 W/m K. The highest dimensionless figure of merit is 0.031at temperature 973 K in La0.88Sr0.12FeO3.