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Study on Bandwidth Frequency of Servovalve based on Metering Cylinder
Sungdong Kim,Weng-Long An,Sehyeong Jeon 유공압건설기계학회 2015 유공압건설기계학회 학술대회논문집 Vol.2015 No.10
In this study, a metering cylinder was constructed, and the velocity obtained from the linear velocity transducer (LVT) of the cylinder piston was used to evaluate the dynamic performance of an electro-hydraulic servovalve. Frequency response experiments involving the spool displacement and piston velocity (LVT signal) were conducted with different input signal amplitudes, hydraulic pipe diameters, and supply pressures. The spool displacement signal accurately reflected the performance of the servovalve. Meanwhile, the -3 dB bandwidth frequency of the LVT signal was similar to the spool displacement signal, except for a small-amplitude input signal, and the -90° phase lag bandwidth frequency showed some differences.
Kim, Cheol,Cho, Seungbum,Kim, Sungdong,Kim, Sarah Eunkyung Electrochemical Society 2017 ECS journal of solid state science and technology Vol.6 No.12
<P>A p-type oxide is a key element for transparent thin-film transistor applications. Among the various p-type oxides currently available, SnO<SUB>x</SUB> deposited by sputtering is the subject of interest in this study for high-performance and reliable thin films. A tin target or a tin oxide target is typically used to fabricate p-type SnO<SUB>x</SUB> during sputtering. A metallic target provides easy control of various film properties and chemical compositions, while a ceramic target offers structural stability and better control of stoichiometry. To use the advantages of both metallic and ceramic targets, a composite target of Sn and SnO was devised, which may provide reliable p-type SnO<SUB>x</SUB> and better control of structural defects. We evaluated four different composition ratios of Sn+SnO targets: a 100 mol% metallic Sn target, a composite target with 50 mol% Sn powder + 50 mol% SnO powder, a composite target with 20% Sn powder + 80 mol% SnO powder, and a 100 mol% ceramic SnO target. SnO<SUB>x</SUB> films were deposited under various sputtering conditions and analyzed structurally, electrically and optically. The composite target with 20 mol% Sn was found to be a promising candidate for p-type SnO<SUB>x</SUB> films, showing >75% transmittance and high mobility up to 9.07 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP>.</P>
Effects of forming gas plasma treatment on low-temperature Cu-Cu direct bonding
Kim, Sungdong,Nam, Youngju,Kim, Sarah Eunkyung IOP Publishing 2016 Japanese journal of applied physics Vol.55 No.6
<P>Low-temperature Cu-Cu direct bonding becomes of great importance as Cu is widely used as an interconnection material in the packaging industry. Preparing a clean surface is a key to successful Cu-Cu direct bonding. We investigated the effects of forming gas plasma treatment on the reduction of Cu oxide and Cu-Cu bonding temperature. As plasma input power and treatment time increased, Cu oxide could be effectively reduced, and this could be attributed to the enhanced chemical reaction between forming gas plasma and Cu oxide. When the bonding temperature was reduced from 415 to 300 degrees C, the bonding strength of the plasma-treated interface was increased from 1.8 to 5.55 J/m(2) while that of the wet-treated interface was decreased. (C) 2016 The Japan Society of Applied Physics</P>