• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.425-429
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• 2014

Half-metallic nanostructure is highly applicable in the field of Spintronics and electronic device technology. We examine the electronic properties of a ferrocene-based nanowire as a possible candidate for a half-metallic nanostructure using VASP and SIESTA. Ferrocene-based nanowire shows high stability in both binding energy simulation and molecular dynamics (MD) simulation. The density of states (DOS) and the projected DOS of the ferrocene-based nanowire indicate that one-dimensional clustering of ferrocene molecules can be explained because of p-d orbital hybridization between iron and carbon. Half-metallic property and energy dispersion at the Fermi level due to one-dimensional structure is also observed from the DOS results.

• Journal of the Korean institute of surface engineering
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• v.53 no.4
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• pp.144-152
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• 2020

In the manufacturing process of joining of aluminum alloy and polymer, the strength of the metal-polymer joining is greatly influenced by the nanostructure of the oxide film. In this study, we investigated the dependence of joining strength on the thickness, structure, pore formation and surface roughness of the formed film. After the two-step anodization process, the surface oxide layer became thinner and rougher resulting in higher joining strength with the polymer. More specifically, after the two-step anodization, the surface roughness, Ra increased from 2.3 to 3.2 ㎛ with pore of three-dimensional (3D) nanostructure, and the thickness of the oxide film was thinned from 350 to 250 nm. Accordingly, the joining strength of the aluminum alloy with polymer increased from 23 to 30 MPa.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.1
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• pp.12-19
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• 2006

Metalorganic chemical vapor deposition (MOCYD) techniques have been applied to fabricate semiconducting ZnO thin films and nanostructures, which are promising for novel optoelectronic device applications using their unique multifunctional properties. The growth and characterization of ZnO thin films on Si and $SiO_2$ substrates by MOCYD as fundamental study to realize ZnO nanostructures was carried out. The precise control of initial nucleation processes was found to be a key issue for realizing high quality epitaxial layers on the substrates. In addition, fabrication and characterization of ZnO nanodots with low-dimensional characteristics have been investigated to establish nanostructure blocks for ZnO-based nanoscale device application. Systematic realization of self- and artificially-controlled ZnO nanodots on $SiO_2/Si$ substrates was proposed and successfully demonstrated utilizing MOCYD in addition with a focused ion beam technique.

• Journal of Magnetics
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• v.14 no.1
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• pp.31-35
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• 2009

Herein, the Magneto-Optical Kerr Effect (MOKE) signal enhancement in nanostructures in investigated. It is well known that the MOKE signals of ferromagnetic thin films are enhanced with an additional dielectric layer due to multiple reflections. The MOKE signal is modulated with the additional dielectric layer thickness and is at a maximum when reflectivity is at a minimum. This is not always true in the nanostructures due to the contribution from the non-magnetic substrate portion, especially when substrate reflectivity is minimized and the dependence of the additional dielectric layer thickness for the nanostructure is changed in the case of the continuous thin film. We showed that the MOKE signal for nanostructures could be enhanced with a properly designed, dielectric layer in addition to the anti-reflection coated substrates.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.365-366
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• 2007

The dendrimer has been well known as a promising macromolecules for a building the organized nanostructure, which of the size can be controlled and which of periphery can be terminated by various functionalities. Currently a variety of research is being carried out in the field of dendrimer / polymer characterization, nano-scale atomic manipulation, and supramolecular nanostructure analysis. We investigated monolayer behavior and its characteristics at the air-water interface by LB method. In this report, we will present the interfacial properties of dendrimer monolayers on various conditions such as the surface-pressure, barrier speed and spreading quantity.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.170-171
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• 2019

When the cement paste in concrete is exposed to high temperatures, the mechanical performance decreases due to a series of reactions inside the cement. In this study, we investigated the change of nanostructure of $C_3S$ when $C_3S$ was exposed to high temperature using pair distribution function (PDF) based on high energy X-ray scattering. As a result of X-ray diffraction, there was no significant difference when $C_3S$ was heated at $300^{\circ}C$, but most of $Ca(OH)_2$ was decomposed into CaO at $500^{\circ}C$. In addition, it was confirmed that CaO is dominant in the nanostructure when $C_3S$ is heated to $500^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.30 no.4
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• pp.210-217
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• 2021

Gas sensors based on semiconducting metal oxides have attracted considerable attention for various applications owing to their facile, cheap, and small-scale manufacturing processes. Hematite (α-Fe₂O₃) is widely considered as a promising candidate for a gas-sensing material owing to not only its abundance in the earth's crust and low price but also its chemical stability and suitable bandgap energy. However, only a few studies have been performed in this direction because of the low gas response and sluggish response of hematite-based gas sensors. Nanostructures present a representative solution to both overcome these disadvantages and exploit the desirable features to produce high-performance gas sensors. However, several challenges remain for adopting gas sensors based on metal oxide nanostructures, such as improving cost efficiency and facilitating mass production. This review summarizes the recent studies on gas sensors based on hematite nanostructures. It also provides useful insights into various strategies for enhancing the gas-sensing properties of gas sensors based on hematite nanostructures.

• Journal of Sensor Science and Technology
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• v.31 no.4
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• pp.244-248
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• 2022

Recently, several studies on the development of superhydrophobic surfaces using various nano-sized carbon-based materials have been conducted. The superhydrophobic surfaces developed using carbon soot have advantages such as low processing cost and remarkable physical and chemical properties. However, their durability is low. To address this problem, in this study, a superhydrophobic surface with high durability and a multilayer structure was fabricated using ethanol vapor treatment. Candle soot was deposited on an aluminum substrate coated with paraffin wax, and a micro-nano multilayer structure with a size of several micrometers was fabricated via ethanol vapor treatment. The fabricated superhydrophobic surface was confirmed to have a contact angle of at least 156° and high durability. Finally, it was confirmed that ethanol vapor not only changed the nanostructure of carbon but also affected the durability of the structure.

• Journal of Sensor Science and Technology
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• v.32 no.1
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• pp.31-38
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• 2023

Three-dimensional (3D) micro/nanostructures based on soft elastomers have received extensive attention in recent years, owing to their potential and advanced applicability. Designing and fabricating 3D micro/nanostructures are crucial for applications in diverse engineering fields, such as sensors, harvesting devices, functional surfaces, and adhesive patches. However, because of their structural complexity, fabricating soft-elastomer-based 3D micro/nanostructures with a low cost and simple process remains a challenge. Bio-inspired designs that mimic natural structures, or replicate their micro/nanostructure surfaces, have greatly benefited in terms of low-cost fabrication, scalability, and easy control of geometrical parameters. This review highlights recent advances in 3D micro/nanostructures inspired by nature for diverse potential and advanced applications, including flexible pressure sensors, energy-harvesting devices based on triboelectricity, superhydrophobic/-philic surfaces, and dry/wet adhesive patches.

• Current Optics and Photonics
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• v.7 no.5
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• pp.562-568
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• 2023

We designed a combined nanostructure of inverted pyramidal pits and nanoparticles, which can obtain much stronger field enhancement than traditional periodic pits or nanoparticles. The field enhancement |E|/|E₀| is greater than 10 in a large area at 750-820 nm in incident wavelength. |E_max|/|E₀| is greater than 60. Moreover, the hot spot is obtained outside the pits instead of localized inside them, which is beneficial for experiments such as surface-enhanced Raman scattering. The relations between resonant wavelength and structural parameters are investigated. The resonant wavelength shows a linear dependence on the structure's period, which provides a direct way to tune the resonant wavelength. The excitation of a propagating surface plasmon on the periodic structure's surface, a localized surface plasmon of nanoparticles, and a standing-wave effect contribute to the enhancement.