Myung Hwa Kim
Other affiliations: University of California, Santa Barbara, Wayne State University, Stony Brook University ...read more
Bio: Myung Hwa Kim is an academic researcher from Ewha Womans University. The author has contributed to research in topics: Nanowire & Materials science. The author has an hindex of 31, co-authored 152 publications receiving 3028 citations. Previous affiliations of Myung Hwa Kim include University of California, Santa Barbara & Wayne State University.
Papers published on a yearly basis
TL;DR: Hydrophobic sponge structure-based triboelectric nanogenerators using an inverse opal structured film for sustainable energy harvesting over a wide range of humid atmosphere have been successfully demonstrated.
Abstract: Hydrophobic sponge structure-based triboelectric nanogenerators using an inverse opal structured film for sustainable energy harvesting over a wide range of humid atmosphere have been successfully demonstrated. The output voltage and current density reach a record value of 130 V and 0.10 mA cm(-2) , respectively, giving over 10-fold power enhancement, compared with the flat film-based triboelectric nanogenerator.
TL;DR: A colorimetric and fluorescent turn-on carbon dioxide sensor that relies on a polydiacetylene, PDA-1, functionalized with amines and imidazolium groups, which allows for the selective sensing of CO2 with high sensitivity, down to atmospheric concentrations.
Abstract: We developed a colorimetric and fluorescent turn-on carbon dioxide sensor that relies on a polydiacetylene, PDA-1, functionalized with amines and imidazolium groups. The pendant amines react with CO2 under basic conditions to form carbamoate anions, which partially neutralize the polymer’s positive charges, inducing a phase transition. PDA-1 allows for the selective sensing of CO2 with high sensitivity, down to atmospheric concentrations. Naked-eye detection of CO2 is accomplished either in water solutions of PDA-1 or in the solid state with electrospun coatings of PDA-1 nanofibers.
TL;DR: The two time scales over which H-related processes occur in VO(2) likely signal the involvement of two distinct mechanisms influencing the electronic structure of the material one of which involves electron-phonon coupling pursuant to the modification of the vibrational normal modes of the solid by the introduction of H as an impurity.
Abstract: Exceptionally sensitive hydrogen sensors were produced using Pd-nanoparticle-decorated, single vanadium dioxide nanowires. The high-sensitivity arises from the large downward shift in the insulator to metal transition temperature following the adsorption on and incorporation of atomic hydrogen, produced by dissociative chemisorption on Pd, in the VO2, producing ∼1000-fold current increases. During a rapid initial process, the insulator to metal transition temperature is decreased by >10 °C even when exposed to trace amounts of hydrogen gas. Subsequently, hydrogen continues to diffuse into the VO2 for several hours before saturation is achieved with only a modest change in the insulator to metal transition temperature but with a significant increase in the conductivity. The two time scales over which H-related processes occur in VO2 likely signal the involvement of two distinct mechanisms influencing the electronic structure of the material one of which involves electron−phonon coupling pursuant to the mod...
TL;DR: Three o-phenylendiamine derivatives, containing 4-chloro-7-nitrobenzo[c][1,2,5]oxadiazole, rhodamine, and 1,8-naphthalimide moieties, were prepared and tested as phosgene chemosensors and display distinct color and fluorescence changes upon exposure to phosGene even in the solid state.
Abstract: Three o-phenylendiamine (OPD) derivatives, containing 4-chloro-7-nitrobenzo[c][1,2,5]oxadiazole (NBD-OPD), rhodamine (RB-OPD), and 1,8-naphthalimide (NAP-OPD) moieties, were prepared and tested as phosgene chemosensors. Unlike previously described methods to sense this toxic agent, which rely on chemical processes that transform alcohols and amines to respective phosphate esters and phosphoramides, the new sensors operate through a benzimidazolone-forming reaction between their OPD groups and phosgene. These processes promote either naked eye visible color changes and/or fluorescence intensity enhancements in conjunction with detection limits that range from 0.7 to 2.8 ppb. NBD-OPD and RB-OPD-embedded polymer fibers, prepared using the electrospinning technique, display distinct color and fluorescence changes upon exposure to phosgene even in the solid state.
TL;DR: An electronic nose (e-nose) strategy is described based on SnO(2) nanowire arrays whose sensing properties are modified by changing their operating temperatures and by decorating some of the nanowires with metallic nanoparticles.
Abstract: An electronic nose (e-nose) strategy is described based on SnO2nanowire arrays whose sensing properties are modified by changing their operating temperatures and by decorating some of the nanowires with metallic nanoparticles. Since the catalytic processes occurring on the metal nanoparticles depend on the identity ofthemetal,decoratingthesemiconductingnanowireswithvariousmetalnanoparticlesisakintofunctionalizing themwithchemicallyspecificmoieties.Otherthanthesynthesisofthenanowires,allotherstepsinthefabrication of the e-nose sensors were carried out using top-down microfabrication processes, paving the way to a useful strategyformakinglowcost,nanowire-basede-nosechips.Thesensorsweretestedfortheirabilitytodistinguish threereducinggases(H2,CO,andethylene),whichtheywereabletodounequivocallywhenthedatawasclassified usinglineardiscriminantanalysis.Thediscriminatingabilityofthise-nosedesignwasnotimpactedbythelengths or diameters of the nanowires used.
01 Jan 2002
01 Aug 2001
TL;DR: The study of distributed systems which bring to life the vision of ubiquitous computing systems, also known as ambient intelligence, is concentrated on in this work.
Abstract: With digital equipment becoming increasingly networked, either on wired or wireless networks, for personal and professional use alike, distributed software systems have become a crucial element in information and communications technologies. The study of these systems forms the core of the ARLES' work, which is specifically concerned with defining new system software architectures, based on the use of emerging networking technologies. In this context, we concentrate on the study of distributed systems which bring to life the vision of ubiquitous computing systems, also known as ambient intelligence.
TL;DR: In this article, the hydrogen (H2) and oxygen (O2) fuel cell is the one with zero carbon emission and water as the only byproduct, which is essential to ensure higher life cycle and less decay in cell efficiency.
Abstract: Increasing demand for finding eco-friendly and everlasting energy sources is now totally depending on fuel cell technology. Though it is an eco-friendly way of producing energy for the urgent requirements, it needs to be improved to make it cheaper and more eco-friendly. Although there are several types of fuel cells, the hydrogen (H2) and oxygen (O2) fuel cell is the one with zero carbon emission and water as the only byproduct. However, supplying fuels in the purest form (at least the H2) is essential to ensure higher life cycles and less decay in cell efficiency. The current large-scale H2 production is largely dependent on steam reforming of fossil fuels, which generates CO2 along with H2 and the source of which is going to be depleted. As an alternate, electrolysis of water has been given greater attention than the steam reforming. The reasons are as follows: the very high purity of the H2 produced, the abundant source, no need for high-temperature, high-pressure reactors, and so on. In earlier days,...
TL;DR: In this article, high performance gas sensors prepared using p-type oxide semiconductors such as NiO, CuO, Cr2O3, Co3O4, and Mn3O3 were reviewed.
Abstract: High-performance gas sensors prepared using p-type oxide semiconductors such as NiO, CuO, Cr2O3, Co3O4, and Mn3O4 were reviewed. The ionized adsorption of oxygen on p-type oxide semiconductors leads to the formation of hole-accumulation layers (HALs), and conduction occurs mainly along the near-surface HAL. Thus, the chemoresistive variations of undoped p-type oxide semiconductors are lower than those induced at the electron-depletion layers of n-type oxide semiconductors. However, highly sensitive and selective p-type oxide-semiconductor-based gas sensors can be designed either by controlling the carrier concentration through aliovalent doping or by promoting the sensing reaction of a specific gas through doping/loading the sensor material with oxide or noble metal catalysts. The junction between p- and n-type oxide semiconductors fabricated with different contact configurations can provide new strategies for designing gas sensors. p-Type oxide semiconductors with distinctive surface reactivity and oxygen adsorption are also advantageous for enhancing gas selectivity, decreasing the humidity dependence of sensor signals to negligible levels, and improving recovery speed. Accordingly, p-type oxide semiconductors are excellent materials not only for fabricating highly sensitive and selective gas sensors but also valuable additives that provide new functionality in gas sensors, which will enable the development of high-performance gas sensors.