High voltage impulse(HVI) has been gained attention as an alternate technique controlling CaCO3 scale formation. Investigation of key operational parameters for HVI is important, however, those had not been reported yet. In this study, the effect of temperature and applied voltage of HVI on Ca2+ concentration was studied. As the applied voltage from 0 to 15kV and the temperature increased from 20 to 60°C, the Ca2+ concentration decreased, indicating that the aqueous Ca2+ precipitated to CaCO3. The Ca2+ concentration decreased up to 81% under the condition of 15kV and 60°C. Rate constant for the precipitation reaction, k was determined under different temper1ature and voltage. The reaction rate constant under the 15kV and 60°C condition was evaluated to 66☓10-3 L/(mmol·hr), which was 5 times greater than the k of the reaction without HVI at same temperature. The increases in k by HVI at higher temperature region(40 to 60°C) was much greater than at lower temperature region(20 to 40°C), which implies temperature is more important parameter than voltage for reducing Ca2+ concentration at high temperature region. These results show that the HVI induction accelerates the precipitation to CaCO3, particularly much faster at higher temperature.

This study investigated the effect of wire diameter and applied voltage on the fabrication of Ni-free Fe-based alloy nano powders by employing the PWE (pulsed wire evaporation) in liquid, for high temperature oxidation-resistant metallic porous body for high temperature particulate matter (or soot) filter system. Three different diameter (0.1, 0.2, and 0.3 mm) of alloy wire and various applied voltages from 0.5 to 3.0 kV were main variables in PWE process, while X-ray diffraction (XRD), field emission scanning microscope (FE-SEM), and transmission electron microscope (TEM) were used to investigate the characteristics of the Fe-Cr-Al nano powders. It was controlled the number of explosion events, since evaporated and condensed nano-particles were coalesced to micron-sized secondary particles, when exceeded to the specific number of explosion events, which were not suitable for metallic porous body preparation. As the diameter of alloy wire increased, the voltage for electrical explosion increased and the size of primary particle decreased.

본 논문은 순차적으로 전압 인가된 RF MEMS 스위치를 이용하여 재구성 슬롯 안테나를 설계하였다. MEMS 스위치의 구동전압은 하부 전극과 상부 스위치 사이의 에어캡 높이에 따른 스위치의 특성을 ANSYS 시뮬레이션으로 분석하였다. MEMS 스위치의 구동전압은 하부전극과 상부 스위치 사이의 에어캡 높이와 스위치 형상에 의해 결정된다. 설계된 MEMS 스위치의 길이는 각각 240μm, 320 μm, 400 μm 이고, 에어캡은 6μm이었다. 설계된 슬롯 안테나는 전체크기가 10 mm x 10 mm이며, 슬롯의 크기는 길이가 500 μm, 폭이 200 μm이었다. 그리고 CPW 급전선은 전체의 길이는 5 mm이며, 입구에서의 CPW는 30-80-30 μm이괴, 슬롯에서의 CPW는 150-300-150 μm이다. 세안된 소사의 공진주파수의 튜닝은 RF MEMS 스위치에 DC 바이어스를 인가함으로서 안테나의 전기적인 길이를 변화시켜 이루어진다. 설계된 슬롯 안테나를 시뮬레이션, 제조 및 측정을 하였다.