Geon Hong Lee

ordered pore array in anodic aluminum oxide was fabricated by anodizing pure aluminum. Theorder of a pore array was affected by anodizing voltage, electrolyte temperature, and first anodizing time. A regularpore array with mean diameter of 24 nm and interpore distance of 109 nm could be formed by two-step anodizationat 40 V, oxalic acid concentration of 0.3 M and electrolyte temperature of 15oC. The measured interpore distanceshowed linearity with anodizing voltage. The diameter of pores was adj

As a part of the electromagnetic spectrum, microwaves heat materials fast and efficientlyvia direct energy transfer, while conventional heating methods rely on conduction and convection. To date, the use of microwave heating in the research of carbon-based materialshas been mainly limited to liquid solutions. However, more rapid and efficient heating ispossible in electron-rich solid materials, because the target materials absorb the energy ofmicrowaves effectively and exclusively. Carbon-based

A CNT yarn is a collection of interlocked CNTs which form a long and continuous fiber of macroscopic scale. CNT yarns of more than a kilometer are now available so that they have been drawing ever-growing attention from the scientific community. In principle, CNT yarns can inherit the excellent electrical, mechanical and chemical properties of CNTs provided they are produced perfectly. In this perspective review, the production methods of CNT yarns are extensively investigated and reported in de

Amorphous zinc phosphate nanospheres were prepared via a sonochemical route. Zinc phosphate nanospheres were uniform in shape with an average diameter of 210 nm. The average diameter of nanospheres could be controlled by changing the pH of a precursor solution. This sonochemical method is simple, facile, economical, and environmentally benign. Non-crystalline characteristics of as-prepared zinc phosphate nanospheres were confirmed by X-ray diffraction, transmission electron microscopy, and FT-IR

Superhydrophobic polytetrafluoroethylene (Teflon(R), DuPont) sub-micro and nanostructures were fabricated by the dipping method, based on anodization process in oxalic acid. The polymer sticking phenomenon during the replication creates the sub-microstructures on the negative polytetrafluoroethylene nanostructure replica. This process gives a hierarchical structure with nanostructures on sub-microstructures, which looks like the same structures as lotus leaf and enables commercialization. The di

A new method for the measurement of pore size of the porous-type anodic aluminum oxide (AAO) using atomic force microscopy(AFM) is proposed. The measurement of the pore size by AFM makes no damage to the specimen. AAO lm can be referred as a nano-honeycomb structure because the pore shape of AAO is like the honeycomb structure and its pore size is in the nanometer scale. Tomeasure the pore sizes from AFM images, it is assumed that the top surface of AAO is not etched much in the pore widening pr

Microwave irradiation was used to obtain a variety of CuO crystal morphologies, including leaf-like, dandelion-like, and hollow structures. The morphology of the CuO crystals was controlled by varying the alkali source (NaOH, hexamethylenetetramine, ammonia, or urea) and heating at 95 oC for 1 hr. The X-ray diffraction patterns of as-prepared CuO crystals were consistent with high quality crystals with a monoclinic crystal structure. Field emission scanning electron microscopy (FE-SEM) and tunne

The phase equilibria of methane hydrates were measured in high concentration KCl brines (up tosaturation concentration) at ultra-high pressures (up to 200 MPa). The results show the hydrateequilibrium boundary moves to lower temperature and higher pressure as the KCl concentrationincreased up to the saturation limit and the hydrate equilibrium is unchanged from the saturationconcentration for four-phase equilibrium. From the measurements at the saturation concentration, wealso determine the pres

Variable-energy positrons are combined with Auger electron spectroscopy, scanning electron microscopy, and scratch test critical load measurements to study interfacial properties in thin film adhesion. This work complements an earlier investigation of the adhesion strength enhancement produced by ion bombardment of the substrate surface before deposition. In this study, we have investigated SiO2 films deposited by radio-frequency (RF) sputtering onto stainless steel substrates. Extended ion bomb

A simple and facile sonochemical route was described for the fabrication of diameter-controlled ZnO nanorod arrays on Si wafers. The diameter of ZnO nanorods was controlled by the concentration of zinc cations and hydroxyl anions in aqueous precursor solution. At high concentration of the precursor solution, thick ZnO nanorod arrays were formed. On the contrary, thin ZnO nanorod arrays were formed at low concentration of the precursor solution. The average diameter of ZnO nanorods varies from 40

Anodic aluminum-oxide (AAO) templates were fabricated by two-step anodizing an Al lm. After the Co catalyst had been electrochemically deposited onto the bottom of the AAO template, carbon nanotubes (CNTs) were grown by using catalytic pyrolysis of C2H2 and H2 at 650 C. Overgrowth of CNTs with low density on the AAO templates was observed. The eld-emission measurements on the samples showed a turn-on eld of 2.17 V/m and a eld enhancement factor of 5700. The emission pattern on a phosphor screen

Gas hydrates are considered a nuisance in the flow assurance of oil and gas production since they can block the flowlines, consequently leading to significant losses in production. Hydrate avoidance has been the traditional approach, but recently, hydrate management is gaining acceptance because the practice of hydrate avoidance has become more and more challenging. For better management of hydrate formation, we investigated the risk of hydrate formation based on the subcooling range in which hy

Highly crystalline and few-walled boron nitride nanotubes (BNNTs) had been synthesized by laser ablation using only ammonia borane as a precursor. As a molecular precursor, ammonia borane supplied both B and N atoms with a ratio of 1:1, and BNNTs were formed via the homogeneous nucleation of BN radicals, not the growth from boron nano-droplets, which is a generally accepted growth mechanism of the laser-grown BNNTs. Owing to the absence of amorphous boron impurities, the van der Waals interactio