• Korean Journal of Materials Research
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• v.19 no.9
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• pp.494-498
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• 2009

The thermoluminescent phosphors of LiYSi$O_4$ containing rare earth metal(La) dopants of 1 wt.%5 wt.% were prepared, and their TL characteristics have been investigated as a function of parameters such as the doping level and the heating rate. The grain size and cooling temperature of the highly sensitive LiYSi$O_4$: La phosphors have been investigated. The glow curve of LiYSi$O_4$: La has two peaks ($P_1,\;P_2$), and the peak height ratio of the two peaks is called $P_2/P_1$; here, the main peak is $P_2$. Experimental results indicate that the peak height ratios of the glow curve for LiYSi$O_4$: La are clearly correlated with the grain size and cooling temperature. The maximum $P_2/P_1$ ratio 3.25, the maximum sensitivity was observed for a grain size between 100-150 ${\mu}m$. The intensity of the TL peak of the phosphors was linearly proportion to the dose of X-rays.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.197-204
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• 2014

In this paper an Improved Zero Voltage Zero Current Pulse Width Modulation Forward converter which employs a simple resonance snubber circuit is introduced. A simple snubber circuit consists of a capacitor, an inductor and two diodes. In proposed converter, switch Q1 operates at ZCS turn-on, and ZVS turn-off conditions and all-passive semiconductor devices operate at ZVZCS turn-on and turn-off state. The proposed converter is analyzed and various operating modes of the ZVZCS-PWM forward converter are discussed. Analysis and design considerations are presented and the prototype experimental results of a 100w (40 V/2.5A) proposed converter operating at 30 KHz switching frequency confirm the validity of theoretical analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.9
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• pp.883-891
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• 2013

In wireless smart phone charging scenario, the transmitter pad is larger than the size of the receiver pad. Thus, it is important to supply a constant power to the receiver regardless of its location. In this paper, we propose a new method to regulate the receiver's power by adjusting a drain bias of class E power amplifier. The proposed LF-band wireless power transfer system is as follows: a buck converter power supply which is controlled by a pulse width modulation(PWM) IC TL494, a class E amplifier using a low cost IRF510 power MOSFET, a transmitter coil whose dimension is $16cm{\times}18cm$, a receiver coil whose dimension is $6cm{\times}8cm$, and a full bridge rectifier using Schottky diodes. A measured performance show a maximum output power of 4 W and system efficiency of 67 % if we fix the bias voltage. If we adjust the bias voltage, the received power can be maintained at a constant power of 2 W regardless of receiver pad location.

• Journal of environmental and Sanitary engineering
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• v.3 no.1 s.4
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• pp.41-67
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• 1988

Twelve residual pesticides which is applied mainly on the fruits and vegetables cultivation were tested for mutagenic activity using Salmonella typhimurium. The results were as follows. 1) The pesticides tested - Thalonil, Monopho, Tedion, Danoton, Ometon, Prosing, EPN, Phentoate, Parathion, 8appiran and Captan-, except Dicofol, showed mutagenic activity. Especially, the pesticides which activated with 8-9 mixture gave strong mutagenic activity. 2) With Salmonella typhimurium TA100, the pesticides Monopho, Parathion and Sappiran showed mutagenic activity at $0.5{\mu}g/plate;\;Ometon,\;0.01\; t.tl/plate;Thalonil,\;0.20{\mu}g/plate;\;Prosing,\; 0.20{\mu}l/plate;$ Tedion, Danoton and Phentoate, $1.0\;{\mu}l/plate;\;and\;Captan,\;1.0\;{\mu}g/plate.$ 3) With Salmonella typhimurium TA98, the pesticide Sappiran showed mutagenic activity at $0.02\;{\mu}g/plate;\;Thalonil,\;0.05\;{\mu}g/plate;\;EPN,\;0.05\;{\mu}/plate;\; Phentoate,\;0.10\; {\mu}l/plate;\;Danoton,\;0.50\;{\mu}l/plate;$ Prosing, $ 0.50\;{\mu}g/plate;\;and\;Tedion\;and\;Monopho,\;1.0\;{\mu}l/plate.$ 4) With Salmonella typhimurium TA1535, The pesticides Captan and Danoton showed mutagenic activity at $0.10\;{\mu}g/plate\;and\;0.20\;{\mu}g/plate,\;respectively.$ 5) With Salmonella typhimurium TA1538, The pestides Phentoate showed mutagenic activity at $0.05\;{\mu}l/plate;\;Monopho,\;0.10\;{\mu}l/plate;\;Thalonil,\;0.20 {\mu}g/plate;\;and\;Tedion\;and\;EPN,\;1.0\;{\mu}l/plate.$ 6) The pesticides which commonly showed high mutagenic activity were Thalonil, Phentoate, Parathion and Sappiran. The pesticides Ometon and EPN showed mutagenic activity at only TA100 and TA98, respectively.