Changhwan Lee

Naive Bayesian learning has been popular in data mining applications. However, the performance of naive Bayesian learning is sometimes poor due to the unrealistic assumption that all features are equally important and independent given the class value. Therefore, it is widely known that the performance of naive Bayesian learning can be improved by mitigating this assumption, and many enhancements to the basic naive Bayesian learning have been proposed to resolve this problem including feature se

oxidation of the Cu layer. Our results can provide a better understanding for copper-based hot electron photovoltaics, which could lead to more efficient plasmonic energy conversion.

Energy conversion from light to electricity mediated by hot electrons in a plasmonic metal nanostructure caused by the decay of surface plasmons has been proposed as a promising way to obtain novel photovoltaics and photocatalytic devices. In Schottky barriers composed of metal nanostructures supported on a semiconductor surface, hot electrons produced in the metal with sufficient photon energy can be extracted into the conduction band of the semiconductor by overcoming the Schottky barrier. An

The enhancement of hot electron generation using plasmonic nanostructures is a promising strategy for developing photovoltaic devices. Here, we show that hot electron flow generated in plasmonic Au/TiO 2 nanodiodes by incident light can be amplified when PbS quantum dots are deposited onto the surface of the nanodiodes. The effect is attributed to efficient extraction of hot electrons via a three-dimensional Schottky barrier, thus giving new pathways for hot electron transfer. We also demonstrat

Au-TiO2-Ti nanodiodes with a metal-insulator-metal structure were used to probe hot electron flows generated upon photon absorption. Hot electrons, generated when light is absorbed in the Au electrode of the nanodiode, can travel across the TiO2, leading to a photocurrent. Here, we demonstrate amplification of the hot electron flow by (1) localized surface plasmon resonance on plasmonic nanostructures fabricated by annealing the Au-TiO2-Ti nanodiodes, and (2) reducing the thickness of the TiO2.

In this paper, the Newton-Raphson method, using two-directional (anisotropic) material properties, is applied to the analysis of a three-phase transformer. A new two-dimensional (2-D) model that reflects three-dimensional manufacturing effects, such as air-gap and overlapped stacking, is proposed. These effects cannot be dealt with by conventional 2-D methods. In addition, the new method obtains the current waveform phase difference with respect to the voltage source waveform. The analysis is pe

Upconverting nanoparticles (UCNPs) compose a class of luminescent materials that utilize the unique wavelength-converting properties of lanthanide (Ln) ions for light-harvesting applications, photonics technologies, and biological imaging and sensing experiments. Recent advances in UCNP design have shed light on the properties of local color centers, both intrinsic and controllably induced, within these materials and their potential influence on UCNP photophysics. In this review, we describe fun

The design of a transformer should consider the analysis of the load variation. This paper describes the current wave calculation when the load condition varies for the newly proposed two-dimensional model in previous work, which can reflect the three-dimensional effects such as air gap and overlapped stacking. The analysis includes the Newton-Raphson method, considering two-directional (anisotropic) material properties. The methods are applied to the analysis of a three-phase transformer under

Materials whose luminescence can be switched by optical stimulation drive technologies ranging from superresolution imaging1-4, nanophotonics5, and optical data storage6-8, to targeted pharmacology, optogenetics, and chemical reactivity9. These photoswitchable probes, including organic fluorophores and proteins, are prone to photodegradation, and often require phototoxic doses of ultraviolet (UV) or visible light. Colloidal inorganic nanoparticles have significant stability advantages over exist

Abstract The liner of type 3 high-pressure vessel is manufactured by a D.D.I. (Deep drawing and ironing) process for the cylinder part, which is a continuous process that includes a drawing process to reduce the diameter of the billet and a subsequent ironing process to reduce the thickness of the billet. But the wall thickness of type 3 pressure vessel liners used in vehicles and ships is required to be 5 mm. Excessive wall thickness not only increases the weight of hydrogen vehicles and ships