• Membrane Journal
• /
• v.22 no.1
• /
• pp.35-45
• /
• 2012

We prepared the highly ordered nano-wires of polypyrrole, polyaniline conductive polymers and polypyrrole/ polyaniline conductive copolymers by templating the anodic aluminum oxide (AAO) porous membrane, in which pore diameter was 20 nm, 100 nm and 200 nm. Those conductive polymers were grown from pore inner surface of AAO membrane forming hollow tubes and then wire structures were formed after 3 hour polymerization. By removing AAO membrane templates using sodium hydroxide solution, the conductive polymer nano-wires were successfully obtained, of which diameter and length were close to the ones of nano-pores in AAO membrane template. Crystallinity and thermal stability of the conductive polymer nano-wires were higher than irregular ones that prepared by solution polymerization. Furthermore, the electrical resistance of conductive polymer nano-wires were reduced by about 4~60% compared with that of the irregular polymers prepared by solution polymerization.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.369-370
• /
• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.615-616
• /
• 2011

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.54 no.6
• /
• pp.239-244
• /
• 2005

Nano-sizedporearrayswerepreparedbytheself-organizationprocessesoftheanodicoxidationusingthealuminumplatewith99.999$\%$purity.Sincethealuminumplatehasaroughsurface,thealuminumplateof1mmthicknesswasanodizedafterthepre-treatmentsofpressing,mechanicalpolishing,thermaloxidation,chemicalpolishing,andelectrochemicalpolishing.Thediameterofthenano-sizedporesandthethicknessofbarrierlayercanbecontrolledbyappliedvoltage.Thethicknessofaluminamembranecanalsobecontrolledbytheanodizingcurrent.Thenano-sizedporeswithdiameterof60$\~$120nm,thedistancebetweenthenearestporesof30$\~$60nm,andthethicknessof6$\~$7Wwereobtainedbytheanodicoxidationprocess.Theporewideningprocesswasemployedforobtainingtheone-channelwithflatsurfacebecausetheporesofthealuminamembranepreparedbythefixedvoltagemethodshowsthestructureoftwo-channelwithroughsurface.

• Journal of the Korean Electrochemical Society
• /
• v.5 no.2
• /
• pp.52-56
• /
• 2002

Tin oxide was coated on graphite particle by sol-gel method and an electrode with this material having microcrystalline structure for lithium ion battery was obtained by heat treatment in the range $400-600^{\circ}C$. The content of tin oxide was controlled within the range of $2.25wt\%\~11.1wt\%$. The discharge capacity increased with the content of tin oxide and also initial irreversible capacity increased. The discharge capacity of tin oxide electrode showed more than 350 mAh/g at the initial cycle and 300 mAh/g after the 30th cycle in propylene carbonate(PC) based electrolyte whereas graphite electrode without surface modification showed 140 mAh/g. When the charge and discharge rate was changed from C/5 to C/2, The discharge capacity of tin oxide and graphite electrode showed $92\%\;and\;77\%$ of initial capacity, respectively. It has been considered that such an enhancement of electrode characteristics was caused because lithium $oxide(Li_2O)$ passive film formed from the reaction between tin oxide and lithium ion prevented the exfoliation of graphite electrode and also reduced tin enhanced the electrical conduction between graphite particles to improve the current distribution of electrode.

• Journal of Integrative Natural Science
• /
• v.12 no.4
• /
• pp.116-121
• /
• 2019

This experiment is to evaluate the physical properties of the hydrogel lens with the addition of carbon-based nanomaterials, Graphene oxide and Carbon nanotube, and to confirm the improvement of strength. Hyaluronic acid, a hydrophilic substance, was used as an additive by using HEMA (2-hydroxyethyl methacrylate) and ethylene glycol dimethacrylate (EGDMA) as a base monomers. Graphene oxide and two types of Carbon nanotubes(Amide functionalized and Carboxilic acid functionalized) were added 0.1%, 0.3%, 0.5%, respectively, and the physical properties were analyzed by measuring water content, refractive index, breaking strength and SEM image. In the case of the sample added with each carbon nano material, the water content tended to increase for all three materials. The breaking strength tended to increase in Graphene oxide and Carbon nanotube; Carboxilic acid functionalized, but in the case of Carbon nanotube; amide fuctionalized, the breaking strength tended to decrease. However, Carbon nanotube; amide fuctionalized had the highest breaking strength among the three nano materials. Thus, the addition of certain carbon nanomaterials seems to be appropriate for improving the strength of hydrogel lenses.

• Tribology and Lubricants
• /
• v.33 no.6
• /
• pp.275-281
• /
• 2017

In this work, we have fabricated anodic aluminum oxide (AAO) with ordered nanoscale porosity through an anodization process. We deposited gold and nano-organic thin films on the porous AAO surface to protect its structure and reduce friction. We investigated the tribological characteristics of the porous AAO with respect to the protective surface coatings using tribometers. While investigating the frictional characteristics of the samples by applying normal forces of the order of micro-Newton, we observed that AAO without a protective coating exhibits the highest friction coefficient. In the presence of protective surface coatings, the friction coefficient decreases significantly. We applied normal forces of the order of milli-Newton during the tribotests to investigate the wear characteristics of AAO, and observed that AAO without protective surface coatings experiences severe damage due to the brittle nature of the oxide layer. We observed the presence of several pieces of fractured particles in the wear track; these fractured particles lead to an increase in the friction. However, by using surface coatings such as gold thin films and nano-organic thin films, we confirmed that the thin films with nanoscale thickness protect the AAO surface without exhibiting significant wear tracks and maintain a stable friction coefficient for the duration of the tribotests.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.3_1spc
• /
• pp.544-550
• /
• 2013

A grooved surface with anisotropic wettability was fabricated on a silicon substrate using photolithography, reactive ion etching, and a KOH etching process. The contact angles (CAs) of water droplets were measured and compared with the theoretical values in the Cassie state and Wenzel state. The experimental results showed that the contact area between a water droplet and a solid surface was important to determine the wettability of the water. The specimens with native oxide layers presented CAs ranging from $71.6^{\circ}$ to $86.4^{\circ}$. The droplets on the specimens with a native oxide layer could be in the Cassie state because they had relatively smooth surfaces. However, the CAs of the specimens with thick oxide layers ranged from $33.4^{\circ}$ to $59.1^{\circ}$. This indicated that the surface roughness for a specimen with a relatively thick oxide layer was higher, and the water droplet was in the Wenzel state. From the CA measurement results, it was observed that the wetting on the grooved surface was anisotropic for all of the specimens.

• Korean Journal of Materials Research
• /
• v.14 no.6
• /
• pp.413-419
• /
• 2004

Recently, Silicon On Insulator (SOI) devices emerged to achieve better device characteristics such as higher operation speed, lower power consumption and latch-up immunity. Nevertheless, there are many detrimental defects in SOI wafers such as hydrofluoric-acid (HF)-defects, pinhole, islands, threading dislocations (TD), pyramid stacking faults (PSF), and surface roughness originating from quality of buried oxide film layer. Although the number of defects in SOI wafers has been greatly reduced over the past decade, the turn over of high-speed microprocessors using SOI wafers has been delayed because of unknown defects in SOI wafers. A new characterization method is proposed to investigate the crystalline quality, the buried oxide integrity and some electrical parameters of bonded SOI wafers. In this study, major surface defects in bonded SOI are reviewed using HF dipping, Secco etching, Cu-decoration followed by focused ion beam (FIB) and transmission electron microscope (TEM).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2002.11a
• /
• pp.494-497
• /
• 2002

In this paper, we have presented the simulation results about threshold voltage of nano scale lightly doped drain (LDD) MOSFET with halo doping profile. Device size is scaled down from 100nm to 40nm using generalized scaling. We have investigated the threshold voltage for constant field scaling and constant voltage scaling using the Van Dort Quantum Correction Model(QM) and direct tunneling current for each gate oxide thickness. We know that threshold voltage is decreasing in the constant field scaling and increasing in the constant voltage scaling when gate length is reducing, and direct tunneling current is increasing when gate oxide thickness is reducing. To minimize the roll-off characteristics for threshold voltage of MOSFET with decreasing channel length, we know u value must be nearly 1 in the generalized scaling.