Kyoung Hwan Choi

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Controlling phase transitions through local strain engineering is an exciting avenue for tailoring the electronic and magnetic properties of materials at the nanoscale. Herein, we demonstrate a tunable semiconducting to metallic phase transition of two-dimensional transition metal dichalcogenides using strain engineering through rolled up MoS2 sheets (named(More)
Elevated-temperature (100~200 °C) polymer electrolyte membrane (PEM) fuel cells have many features, such as their high efficiency and simple system design, that make them ideal for residential micro-combined heat and power systems and as a power source for fuel cell electric vehicles. A proton-conducting solid-electrolyte membrane having high conductivity(More)
The phase transition through local strain engineering is an exciting avenue for controlling electronic, magnetic properties and catalyst activity of materials but complex phenomenon in nanoscience. Herein, we demonstrate the first combinations of bending strain and 2H/1T phase transition by rolling up MoS2 sheets for improving catalytic activity in(More)
2,2:3,3-Bis(4'-hydroxymethylethylenedioxy)-1,7,7-trimethylbicyclo[2.2.1]heptane, abbreviated as CaG, is a compound obtained by transforming a ketone group to a ketal group with camphorquinone and glycerol. The CaG diol has a complex and rigid structure and two primary hydroxyl groups. A polyester series was synthesized with the CaG diol, ethylene glycol,(More)
An improved PEMFC model is developed. The improvement of the model includes modification for electrochemical reaction and mass transfer limitation at cathode and anode side. Global sensitivity analysis is used for evaluating the sensitivity of the model in parameter estimation. The simulation results reveal that estimated mass transfer coefficients depend(More)
Controlling tunable properties by rolling up two dimensional nanomaterials is an exciting avenue for tailoring the electronic and magnetic properties of materials at the nanoscale. We demonstrate the tailoring of a magnetic nanocomposite through hybridization with magnetic nanomaterials using hexagonal boron nitride (h-BN) templates as an effective way to(More)
There have been growing interests in direct patterning of metallic contents on the surface of the substrate without including complex steps of the micro fabrication lithography process. The direct fabrication process using ink-jet printing can be expected to be a powerful tool for both nanotechnology research and applications such as micro electronics.(More)
Palladium-cobalt-phosphorus (PdCoP) catalysts supported on carbon (Ketjen Black) were investigated as a cathode catalyst for oxygen reduction reaction (ORR) in high temperature proton exchange membrane fuel cells (HT-PEMFCs). The PdCoP catalyst was synthesized via a modified polyol process in teflon-sealed reactor by microwave-heating. From X-ray(More)
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