• Advanced Composite Materials
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• v.18 no.3
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• pp.221-232
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• 2009

The allylamine plasma treatment is used to modify the surface properties of vapor grown carbon fibers (VGCF). It is to improve the interfacial bonding between the VGCF and epoxy matrix. The allylamine plasma process was performed by batch process in a vacuum chamber, using gas injection followed by plasma discharge for the durations of 20, 40 and 60 min. The interdependence of mechanical properties on the VGCF contents, treatment time and interfacial bonding between VGCF/ep was investigated. The interfacial bonding between VGCF and epoxy matrix was observed by scanning electron microscopy (SEM) micrographs of nanocomposites fracture surfaces. The changes in the mechanical properties of VGCF/ep, such as the tensile modulus and strength were discussed. The mechanical properties of allylamine plasma treated (AAPT) VGCF/ep were compared with those of raw VGCF/ep. The tensile strength and modulus of allyamine plasma treated VGCF40 (40 min treatment)/ep demonstrated a higher value than those of other samples. The mechanical properties were increased with the allyamine plasma treatment due to the improved adhesion at VGCF/ep interface. The modification of the carbon nanofibers surface was observed by transmission electron microscopy (TEM). SEM micrographs showed an excellent dispersion of VGCF in epoxy matrix by ultrasonic method.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1118-1120
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• 2009

Micro-size CdS spheres of hollow shape were fabricated through the self-assembly of high density arrow-like nanorods. The synthesis of the CdS hollow spheres were accomplished in an aqueous solution of cadmium nitrate and triblock copolymer (Pluronic P123) at low temperature (80 ${^{\circ}C}$) through the slow release of S2- ions from thioacetamide. Morphology of the fabricated CdS hollow spheres was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The results indicate that the arrow-like CdS nanorods are simultaneously grown and attached each other to form the building units that become the spheres with hollow inside as a self-assembled process. The CdS spheres have a diameter of $2{\sim}3 {\mu}m$ and consist of the nanorods with a length of$\sim$800 nm. The nanocrystal building blocks have a hexagonal CdS structure.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.355-362
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• 2009

The chemical modification of multi-wall carbon nanotubes (MWNTs) is an emerging area in material science. In the present study, hydroxyl functionalized oxovanadium(IV) Schiff-base; N,N'-bis(4-hydroxysalicylidene)-ethylene-1, 2-diamineoxovanadium(IV), [VO($(OH)_2$-salen)]; has been covalently anchored on modified MWNTs. The new modified MWNTs ([VO($(OH)_2$-salen)]-MWNTs]) have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron (XPS), UV-Vis, Diffuse reflectance (DRS), FT-IR spectroscopy and elemental analysis. The analytical data indicated a composition corresponding to the mononuclear complex of tetradentate Schiff-base ligand. The characterization of the data showed the absence of extraneous complex, retention of MWNTs and covalently anchored on modified MWNTs. Liquid-phase oxidation of cyclohexane with $H_2O_2$ to a mixture of cyclohexanone, cyclohexanol and cyclohexane-1,2-diol in $CH_3$CN have been reported using oxovanadium(IV) Schiff-base complex covalently anchored on modified MWNTs as catalysts. This catalyst is more selective toward cyclohexanol formation.

• Journal of Hydrogen and New Energy
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• v.14 no.3
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• pp.247-257
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• 2003

To investigate the effect of preparing condition on the physical properties of carbon nanotubes suitable for optical applications, carbon nanotubes were synthesized by thermal chemical vapor deposition using Ni particles as a catalyst on stainless steel substrate and acetylene as a reactant gas. To examine the physical and optical properties, SEM, TEM, Ram an, UV-visible, and photoluminescence spectroscopy were used. The physical properties of carbon nanotubes such as diameter, degree of growth density and morphology were closely related to such experimental conditions as Ni particle size, growing pressure, and etching condit on of Ni particles, it appeared from the light absorbance and photoluminescence spectra of carbon nanotube mixture prepared with an addition of a photopolymer, P3HT(Poly(3-hexylthIop hene)) that carbon nanotube could do a role as a kind of electron acceptor for solar cell application.

• Journal of Hydrogen and New Energy
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• v.23 no.3
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• pp.256-263
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• 2012

We studied the degradation phenomenon of Pt catalyst in PEMFC. We used the electron microscope analysis technique including the ultra-microtome pretreatment method, FEG-SEM and TEM analysis methods for analysis of Pt nanoparticles. The Pt catalyst degradation is observed not only in electrode site but also in membrane site. We investigated these various degradation phenomena. The cathode electrode layer thickness is reduced. The size of the catalyst is increased much larger than initial size in membrane site. The catalyst moved from electrode layer to the electrolyte membrane. The rounded shape of catalyst was changed to the polygon. As a result, we found that the catalyst degradation processes of migration and coarsening occurred by the followings mechanisms; (1) dissolution of Pt ; (2) diffusion of Pt ion ; (3) Pt ion chemical reduction in membrane; (4) Coarsening of Pt particles (Ostwald ripening) ; (5) polygon shape change of Pt by {111} plane growth.

• Journal of Hydrogen and New Energy
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• v.22 no.5
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• pp.656-662
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• 2011

The purpose of this study was to correlate between photoelectrochemcial hydrogen production rate and electron transfer with various types of metal doped $TiO_2$ nanotubes as photoanodes. In order to fabricate light sensitized photoanode, CdS, $WO_3$, and Pt were doped by electrodeposition method. As the results of experiments, the electron transfer was favorable from higher position to lower position of conduction band (CB). In consequence, the higher hydrogen production rate was as follows, CdS/$TiO_2$ (100 $umol/hr-cm^2$) > $WO_3/TiO_2$ (20 $umol/hr-cm^2$) > Pt/$TiO_2$ (10 $umol/hr-cm^2$). The surface characterizations exhibited that crystal structure, morphological and electrical properties of various metal depoed $TiO_2$ nanotubes by the results of SEM, TEM, XPS, and photocurrent measurements.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.4
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• pp.567-572
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• 2015

Discharge characteristics of linear microwave plasma were investigated by using fluid simulation of 2D axis-symmetry based on finite elements method. The microwave power was 2.45 GHz TEM mode and transmitted through linear antenna. Resistive power and pressure were considered simulation variables and argon was used for working gas. A decrease of electron density along the quartz tube was observed in low power condition but relatively uniform plasmas were generated in chamber by increasing the resistive power. The electron temperature was highly detected near the surface of quartz tube because the electron was heated only dielectric surface. The power transmission efficiency decreased and characteristics of surface plasma were observed in high electron density condition.

• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.384-394
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• 1997

Research about Reuse is developed in various direstions, but the sucessful exmples; of the rexuavle objects are very rare in praciice because technical environment to support reuse is short.In this paper we describe a sys-tem for analyxing the information about reusability of C++ objects and for storing and managing the extracted information in information DB.In this development system, user can see the specification information of objects and the quality information of the procedual and object oriented atibutes by browsing.And objests that are not on the reuse unformation DB is analyxed and is tested automatically using the information analyzer by user.We implemented this system using C program in X-Window OSFI/Motif 2.1.1.

• Resources Recycling
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• v.6 no.4
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• pp.31-37
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• 1997

The Mg-ferrite powders were recovered from acid leaching Mg waste by hydrothermal method. Recovering conditions ofMg-Ferrite were investigated m this system and the powders prepared were characterized, using X-ray analysis, chemicalanalysis, SEM. TEM, and VSM. In this study, pH of solution and the kind of neutralizer wcre important factors on thecharacteristics of the product. The optimum condition of recovering MgPenite was the mole ratio of Fe" : Mg"=2'1, reactiontemperature : ZOWC, reaction time.lhr, at pH=lZ, and Oi partial pressure af 2000 psi. And the powders ~ccovered have amonodispersed and spherelike shapes with the narrow sue distribulion.ow sue distribulion.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.4
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• pp.147-151
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• 2002

The resistances of metal2 contact to metall and poly Si are checked by various RF etch conditions in terms of pre-cleaning. The changes of resistance are evaluated by statistical analysis method(SAS) for the AC bias power, coil power and RF target. The contact area on poly Si is shown by TEM image and the distributions of contact resistance according to ar etch target and RTP are investigated. The RTP groups have larger variations than normal RF etch targets. When the RF etch target becomes lower and coil power becomes higher, the resistances of metal2 contact to metals and poly Si have lower contact resistance. But the condition of AC bias power did not satisfied low meta12 contacts resistance for metall and poly Si simultaneously. The R-square of ststistical analysis was 0.98 for resistances of meta12 contact to poly Si and 0.87 for resistances of meta12 contact to metall.