• Journal of Powder Materials
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• v.27 no.1
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• pp.63-71
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• 2020

It is necessary to fabricate uniformly dispersed nanoscale catalyst materials with high activity and long-term stability for polymer electrolyte membrane fuel cells with excellent electrochemical characteristics of the oxygen reduction reaction and hydrogen oxidation reaction. Platinum is known as the best noble metal catalyst for polymer electrolyte membrane fuel cells because of its excellent catalytic activity. However, given that Pt is expensive, considerable efforts have been made to reduce the amount of Pt loading for both anode and cathode catalysts. Meanwhile, the atomic layer deposition (ALD) method shows excellent uniformity and precise particle size controllability over the three-dimensional structure. The research progress on noble metal ALD, such as Pt, Ru, Pd, and various metal alloys, is presented in this review. ALD technology enables the development of polymer electrolyte membrane fuel cells with excellent reactivity and durability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.749-752
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• 2001

Very fine cobalt oxide xerogel and ambigel powder were prepared using a unique solution chemistry associated with the sol-gel process. The mesoporous structure of the initial gel is maintained by removing fluid under conditions where the capillary forces that result extraction are either low or no existent, are either low or nonexistent. Controlling both the pore and solid architecture on the nanoscale offers a strategy for the design of supercapacitor. The results materials determine by using electrode that mixed ketjen black and PVdF. But CoO$\_$x/ have the low voltage, so we experimente to change electrolyte and various concentration.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.23-26
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• 2004

Ag/Ni multilayers with different bilayer thickness between 3 and 100 nm produced by DC magnetron puttering have been studied by cross-sectional TEM and nanoindentation. The micrograph shows perfect layered structure with sharp interfaces between Ag and Ni layers. Absolute hardness is calculated as a reference value to compare hardness of specimens regardless of indent depth. A hardness enhancement of nearly $100\%$ over the rule-of-mixtures values, calculated from the measured hardness of single Ag and Ni thin films, is observed. The hardness increases with decreasing bilayer thickness until 8nm. This enhancement shows a good agreement with Hall-Petch relation using grain size (one half of the bilayer thickness) confined within a layer. The deformation behavior can be explained by dislocation pile-up in smaller grains.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.577-580
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• 2001

Very fine cobalt oxide ambigel powder were prepared using a unique solution chemistry associated with the sol-gel process. The mesoporous structure of the initial gel is maintained by removing fluid under conditions where the capillary forces that result extraction are either low or no existent, are either low or nonexistent. Controlling both the pore and solid architecture on the nanoscale offers a strategy for the design of supercapacitor. But $CoO_x$ have the low voltage, so we experiment using Co/PVA composite electrode.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.82-82
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• 2017

It is a great challenge to design and develop biologically inspired hierarchical platforms composed of nano and sub-nanopatterned topography for cell and tissue engineering. In this work, we have developed the novel platforms as a synthetic extracellular matrix using graphene and nanopatterned substrates for promoting functions of cells. Monolayer graphene was coated on the nanopatterned matrix with various nanoscale parallel ridges and grooves as scaffolds with hierarchical structures. Strictly, it was found that graphene-matrix nanotopography platforms could promote the functions of cells including stem cells, osteoblast cells, and endothelial cells through the synergically controlled cell-substrate and cell-cell interactions. Our results proposed that the graphene-based nanopatterned scaffolds would allow us to set up an efficient strategy for designing advanced biomimetic engineering systems toward stem cell-based tissue regeneration.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.90-95
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• 2005

The wire-arc process is a low-cost thermal spray method simply utilizes electrical energy to melt the feedstock wire. It is more userful for field applications, especially to coat large surface area. In this paper, a special Fe-based alloy coatings by using the wire-arc process were developed. Nanoscale composite coatings were achieved either during spraying or through a post heat treatment. As-sprayed Fe-based alloy coatings had been an amorphous matrix structure, after heating to $700^{\circ}C$ for 10 minutes a solid state transformation occurred in the some fraction of amorphous matrix which resulted in the formation of nanostructured recrystallized phase. Scanning electron microscopy (SEM) and field emotional scanning electron microscope(FE-SEM) were applied to analyze the microstructure of the coatings. Additionally hardness and bend resistance of the Fe-based alloy coatings were examined, and these results were compared with those of partially stabilized zirconia(PSZ) coatings by using the plasma spray process.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.56-58
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• 2005

To illustrate an application of the field effect transistor (FET) structure, this study suggests a new cantilever, using atomic force microscopy (AFM), for sensing surface potentials in nanoscale. A combination of the micro-electromechanical system technique for surface and bulk and the complementary metal oxide semiconductor process has been employed to fabricate the cantilever with a silicon-on-insulator (SOI) wafer. After the implantation of a high-ion dose, thermal annealing was used to control the channel length between the source and the drain. The basic principle of this cantilever is similar to the FET without a gate electrode.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.275-276
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• 2003

Electrostatic spinning or electrospinning has been recently paid attention to prepare ultrafine fiber mats which are composed of diameters in a range of submicrons to nanoscale size[l]. Due to small diameters and porous structure, electrosun fibers have a high specific surface area and expected to use for broad applications, such as filters, membranes, wound dressing materials, artificial blood vessels. a nonwoven fabric, a reiforcement of nanocomposites[2,3], etc. (omitted)

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.415-420
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• 2007

In analyzing the nano-scale behavior of nano devices or materials, QC method is efficient because it does not treat all the atoms. But for more accurate analysis in QC method, it is important to consider temperature and surface effects. In finite temperature, free energy is considered instead of potential energy. Because the surface area to volume ratio increases as the length scale of a body decreases, the surface effects are more dominant. In this paper, temperature related Cauchy-Born rule and surface Cauchy-Born rule are proposed to configurate the strain energy density. This method is applied to small and homogeneous deformation in two dimensional problem using finite element simulation.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.3
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• pp.221-226
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• 2008

A new two dimensional (2-D) analytical model for the Threshold Voltage on dual material surrounding gate (DMSG) MOSFETs is presented in this paper. The parabolic approximation technique is used to solve the 2-D Poisson equation with suitable boundary conditions. The simple and accurate analytical expression for the threshold voltage and sub-threshold swing is derived. It is seen that short channel effects (SCEs) in this structure is suppressed because of the perceivable step in the surface potential which screens the drain potential. We demonstrate that the proposed model exhibits significantly reduced SCEs, thus make it a more reliable device configuration for high speed wireless communication than the conventional single material surrounding gate (SMSG) MOSFETs.