Byung-Min Ahn

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  • Troy Topping, Byungmin Ahn, Ying Li, Steve Nutt, Enrique Lavernia, Troy D Topping +2 others
  • 2015
Aluminum alloys with nanocrystalline (NC) and ultrafine grain (UFG) size are of interest because of their strengths that are typically 30 pct greater than conventionally processed alloys of the same composition. In this study, UFG AA 5083 plate was prepared by quasi-isostatic (QI) forging of cryomilled powder, and the microstructure and mechanical behavior(More)
Dynamic observations of deformation in an ultrafine-grained Al-Mg alloy with bimodal grain structure " Abstract: The tensile properties and deformation response of an ultrafine-grained (UFG) Al–Mg alloy with bimodal grain structure were investigated using a micro-straining unit and a strain mapping technique. Atomized Al 5083 powder was ball-milled in(More)
To assess potential routes for the production of high-strength Al 5083, gas-atomized powder was cryogenically ball-milled, to obtain a nanocrystalline structure, then hot vacuum degassed and consolidated by two methods: (1) hot isostatic pressing (HIPping) and extrusion, and (2) two-step quasi-isostatic (QI) forging. The consolidated billet in both cases(More)
Uniform GaN nanorod arrays are grown vertically by selective area growth on (left angle bracket 0001 right angle bracket) substrates. The GaN nanorods present six nonpolar {1⁻100} facets, which serve as growth surfaces for InGaN-based light-emitting diode quantum well active regions. Compared to growth on the polar {0001} plane, the piezoelectric fields in(More)
BACKGROUND Hepatic stellate cell (HSC) has been suggested to play a role in fibrogenesis in alcoholic liver disease. We evaluate the correlation with fibrogenesis and ultrastructure of hepatic stellate cells in alcoholic fatty liver. METHODS We studied 6 patients with alcoholic fatty liver and 5 non-alcoholic fatty liver. The numbers of fat droplets in(More)
Diametral compression tests were performed on pultruded composite rods comprised of unidirectional glass or carbon fibers in a common matrix. During compression tests, acoustic emission (AE) activity was recorded and images were acquired from the sample for analysis by digital image correlation (DIC). In both composite systems, localized tensile strain(More)
The microstructural evolution of a nanocrystalline Al-Mg alloy was investigated to determine the effects of degassing temperature. Al 5083 powder was ball-milled in liquid nitrogen to obtain a nanocrystalline structure, then vacuum degassed to remove contaminants. The degassed powder was consolidated by cold isostatic pressing (CIP) and then forged to(More)
Disks of commercial Al-1050 and ZK60A alloys were stacked together and then processed by conventional high-pressure torsion (HPT) through 1 and 5 turns at room temperature to investigate the synthesis of an Al–Mg alloy system. Measurements of microhardness and observations of the microstructures and local compositions after processing through 5 turns(More)
Keywords: Thin film transistor Field-effect transistor Chemical sensor Semiconductor Phthalocyanine Porphyrin Tetrabenzoporphyrin Grain size Adsorption Lewis-bases Thin-films Solution-processed Morphology a b s t r a c t Organic thin film transistor (OTFT) chemical sensors rely on the specific electronic structure of the organic semiconductor (OSC) film for(More)
To assess the extent of microfilaments in cholestatic liver diseases we examined the cytoplasmic microfilaments in intrahepatic and extrahepatic cholestasis in man by electron microscopy. Study subjects were two patients with drug-induced intrahepatic cholestasis, three patients with intrahepatic cholestasis due to viral hepatitis, four patients with(More)
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