Steven Ching-Yei Chung

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The performance versus cost tradeoffs of a fully electric, hybrid energy storage system (HESS), using lithium-ion (LI) and lead-acid (PbA) batteries, are explored in this work for a light electric vehicle (LEV). While LI batteries typically have higher energy density, lower internal resistance and longer lifetime than PbA batteries, the module cost of LI(More)
In this paper, a Delay-Locked Loop (DLL) and Phase Locked Loop (PLL) interleaving control scheme is demonstrated for multi-phase dc-dc converters in a light electric vehicle (LEV) application. Three interleaved non-inverting buck-boost (NIBB) sub-converters operate in peak current mode control (PCMC), and a fully digital off-time generator (OTG) is used in(More)
This paper demonstrates a hybrid energy storage system (HESS), comprised of lithium-ion (LI) and lead-acid (PbA) batteries, for a utility light electric vehicle. While LI batteries have superior energy density, lower internal resistance, and longer lifetime than PbA batteries, the module cost is typically three times higher. The objective of this paper is(More)
This paper explores the multi-disciplinary design challenges in building a 240 VAC, 2 kVA modular single-phase inverter with high power-density using wide-bandgap transistors. The compromise between the electrical and mechanical design is extremely important in any high-density power converter. In this work the electrical and mechanical systems were(More)
This pilot study tests the reliability of laser scanning confocal microscopy (LSCM) to quantitatively measure wear on experimental obsidian tools. To our knowledge, this is the first use of confocal microscopy to study wear on stone flakes made from an amorphous silicate like obsidian. Three-dimensional surface roughness or texture area scans on three(More)
The ortho ester Claisen rearrangement of trisubstituted allylic alcohols exhibits significant levels of diastereoselection. In E allylic alcohols, a 1,3-diaxial interaction develops in the chairlike transition state leading to the anti isomer, rendering the reaction syn selective by a factor of 3-5 to 1. In Z allylic alcohols, the 1,3-diaxial interaction(More)
As the person working directly to implement avion-ics modernization, what is your architecture template for change? Ardis: Our change template for modernization as well as other avionics changes is centered around the Viable Combat Avionics (VCA) initiative. Aging avion-ics issues, avionics affordability issues, and viability issues depending on specifics,(More)
The rollout of the first production C-130 aircraft, the C-130A, took place on March 10, 1955. Since then, more than 2,100 C-130s have been built in dozens of variations and are flown by more than 60 nations worldwide. They carry troops, vehicles, and armaments into battle. They drop paratroopers and supplies from the sky. They serve as airborne and ground(More)