A high dc voltage is commonly used in many process industries in testing, research laboratories and others. Currently, a high voltage dc is implemented using transformer. In this paper, a novel high voltage low current transformerless step-up dc-dc converter is presented. The proposed design consists of two step-up dc-dc converters with negative feedback signal and 15 stages of Cockcroft-Walton (C-W) voltage multiplier. The dc input voltage of 5 V triggers the first step-up dc-dc converter circuit to generate 30 V dc voltage and the second step-up dc-dc converter circuit boosts up to 100 V dc voltage. Further, diode-capacitor multiplier circuit is connected at the final stage to achieve 1.6 kV dc output voltages at 200 kHz switching frequency. The simulation results indicate that the proposed dc-dc converter can generate 1.548 kV dc voltage with a load current of 0.16 mA at 10 MΩ load resistor. Meanwhile, the experiment results show that the proposed dc-dc converter can generate 1.475 kV dc voltage with 80 % efficiency. The results validate both the simulation and experimental of the proposed high dc voltage power supply module.
A Metal-Insulator-Metal (MIM) capacitor with high capacitance, high breakdown voltage, and low leakage current is aspired so that the device can be applied in many electronic applications. The most significant factors that affect the MIM capacitor's performance is the design and the dielectric materials used. In this study, MIM capacitors are simulated using different dielectric materials and different number of dielectric layers from two layers up to seven layers. The effect of the different dielectric constants (k) to the performance of the MIM capacitors is also studied, whereas this work investigates the effect of using low-k and high-k dielectric materials. The dielectric materials used in this study with high-k are Al 2 O 3 and HfO 2 , while the low-k dielectric materials are SiO 2 and Si 3 N 4 . The results demonstrate that the dielectric materials with high-k produce the highest capacitance. Results also show that metal-Al 2 O 3 interfaces increase the performance of the MIM capacitors. By increasing the number of dielectric layers to seven stacks, the capacitance and breakdown voltage reach its highest value at 0.39 nF and 240 V, respectively.
This study focuses on how important it is to apply politeness in speaking with someone from the perspective of English Education students. To do this research, researchers used qualitative methods. One of the techniques that researchers use in this study is the non-interactive technique that is the questionnaire. This questionnaire was chosen to explore deeper information about the opinions of English Education Students at State Islamic University of North Sumatera Medan starting from the 2nd – 8th Semester (participants or respondents) on the importance of expressing politeness. Researchers chose the questionnaire technique in order to shorten the time and got more participants rather than had to conduct interviews. This study reports the choice of being polite for people is influenced by differences in power relations, such as notion of status, age, gender, and social distance. This study emphasizes that politeness is needed to be implemented since rudeness creates conflict between one to another person.
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