• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.230-231
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• 2006

In this paper, we examined effects by the binder in manufacturing titanium dioxide film for dye sensitized solar cell. Binder(PEG and PEO) was added the amount of 10-40wt% to commercial $TiO_2$ (P25), Respectively. All of $TiO_2$ film was showed porous structure owing to the addition of binders. But the difference of film's porosity could not be confirmed. The transmittance of $TiO_2$ film was decreased with the increase of binder's amount, generally. In case of 20wt%, however. The transmittance of $TiO_2$ films was showed the highest value.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.312-313
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• 2006

The primary aim pursued by the preparation of separation membrane is the preparation of the membrane thin as well as with no defect. The field-flow fractionation deposition is a new molding technology which can overcome the traditional disadvantages such as multi-preparation to the preparation of great area of separation membrane with no defect. Therefor the mainly ingredients which influence the appearance and performance of titanium membrane layer are investigated by scanning electricity mirror (SEM) as well as porous material testing instrument: powder performance prepared and confected; selection of supporting body; sintering system such as temperature and time. It is shown that the membrane thickness can be controlled at $50{\mu}m$ or so; the filtration precision mainly rests with powder performance and selection of supporting body and little sintering system

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.157.1-157.1
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• 2007

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.795-804
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• 2007

Statement of problem. Nano-scale calcium-phosphate coating on the anodizing titanium surface using ion beam-assisted deposition (IBAD) has been recently introduced to improve the early osseointegration. However, not much is known about their surface characteristics that have influence on tissue-implant interaction. Purpose. This study was aimed to investigate microtopography, surface roughness, surface composition, and wettability of the titanium surface modified by the anodic oxidation and calcium phosphate coating using IBAD. Material and methods. Commercially pure titanium disks were used as substrates. The experiment was composed of four groups. Group MA surfaces represented machined surface. Group AN was anodized surface. Group CaP/AN was anodic oxidized and calcium phosphate coated surfaces. Group SLA surfaces were sandblasted and acid etched surfaces. The prepared titanium discs were examined as follows. The surface morphology of the discs was examined using SEM. The surface roughness was measured by a confocal laser scanning microscope. Phase components were analyzed using thin-film x-ray diffraction. Wettability analyses were performed by contact angle measurement with distilled water, formamide, bromonaphtalene and surface free energy calculation. Results. (1) The four groups showed specific microtopography respectively. Anodized and calcium phosphate coated specimens showed multiple micropores and tiny homogeneously distributed crystalline particles. (2) The order of surface roughness values were, from the lowest to the highest, machined group, anodized group, anodized and calcium phosphate deposited group, and sandblasted and acid etched group. (3) Anodized and calcium phosphate deposited group was found to have titanium and titanium anatase oxides and exhibited calcium phosphorous crystalline structures. (4) Surface wettability was increased in the order of calcium phosphate deposited group, machined group, anodized group, sandblasted and acid etched group. Conclusion. After ion beam-assisted deposition on anodized titanium, the microporous structure remained on the surface and many small calcium phosphorous crystals were formed on the porous surface. Nanoscale calcium phosphorous deposition induced roughness on the microporous surface but hydrophobicity was increased.

• Current Photovoltaic Research
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• v.1 no.2
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• pp.90-96
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• 2013

We report here flexible dye-sensitized solar cells (DSSC) based on Ti-mesh electrodes that show good mechanical flexibility and electrical conductivity. $TiO_2$ nanotube arrays prepared by electrochemical anodizing Ti-mesh substrate were used as photoanode. A Pt-coated Ti-mesh substrate was used as counter electrode. The photoanodes were modified by coating a $TiO_2$ porous layer onto the $TiO_2$ nanotubes in order to increase the specific surface area. To increase the long term stability of the DSSCs, a gel type electrolyte was used instead of a conventional liquid type electrolyte. The DSSC based on $33.2{\mu}m$ long porous $TiO_2$ nanotubes exhibited a better energy conversion efficiency of ~2.33%, which was higher than that of the DSSCs based on non-porous $TiO_2$ nanotubes.

• Journal of Biomedical Engineering Research
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• v.41 no.1
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• pp.14-21
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• 2020

Recently, porous additive manufactured(AM) cages have been introduced to provide more desirable stiffness and may be beneficial to bone ingrowth. They are designed to attempt to reduce the subsidence problem of traditional titanium cage and to get osseointegrative property that PEEK doesn't have. This study was performed to evaluate the mechanical performance of newly developed lumbar porous AM cages. Three types of mechanical tests were performed in accordance with the ASTM standards: Static compression, compression-shear, and subsidence tests. The porous AM cages with 60% porosity showed similar device stiffness and strength as the various products submitted to FDA 510(k), and their wider contact area improved the subsidence test results by about 50%. In conclusion, the porous AM cages developed in this study were considered mechanically safe and could be an alternative to solid PEEK cages.

• Journal of the Korean Society for Heat Treatment
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• v.22 no.5
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• pp.275-281
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• 2009

The microstructure of copper films prepared by a sputtering apparatus, which was fabricated to enhance the shadowing effect, was investigated by scanning electron microscopy. Black copper films were deposited on copper wires at an Ar pressure of 10 Pa. The black films had an extremely porous structure composed of separated columns. This structure is quite similar to that of black titanium films prepared by cylindrical magnetron sputtering. These results suggest that the porous structure composed of separated columns is easily formed for metal films by enhancing the shadowing effect.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.361-369
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• 2008

The purpose of this study is to make porous oxide film on the surfaces of pure Ti through anodic spark discharge in electrolytic solution containing calcium and phosphate ions, to improve osseointergration by treating fluoride agent. In addition, it is to evaluate the fluoride modified effect on the surface. Commercial pure Ti plate with $20{\times}10{\times}2mm$ and Ti wire with a diameter of 1.5mm and a total length of 15mm were used. After making titanium oxide films converted by anodic spark discharge, anodizing was performed. Fluoride was spreaded to titanium laboratory plate and maintained for 30 minutes after anodizing breakdown. Fluoride ion discharge amount was measured per 24 hours after dipping titanium plate into saline (10ml) and sustaining 90rpm in a pyrostat. Some plates and wires were dipped in Hanks solutions for a month to examine biocompatibility using SEM and XRD. $TiO_2$ film formed by anodic discharge technique showed great roughness and uniform pores which were $1{\sim}3{\mu}m$ in a diameter. Roughness of the films treated with anodic discharge after blasting were higher than the turned ones(P<0.05). Rapid surface activity was observed in the samples treated with $TiF_3$ agent, which immersed in Hanks solution for 30 days. Taking the results into consideration, the fluoride modified implant with anodic discharge demonstrates that it makes uniformly porous oxide film on the surface of implant and properly increase roughness for osseointegration. The implants will achieve greater bone integration after short healing time by improving surface activity.

• Journal of the Korean Ceramic Society
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• v.45 no.11
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• pp.667-674
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• 2008

In this study, we prepared Fe-activated carbon fiber(ACF)/$TiO_2$ composites with titanium (VI) n-butoxide (TNB) as the titanium source for ACF pre-treated with iron compounds through the impregnation method. In terms of textural surface properties, the composites demonstrate a slight decrease in the BET surface area of the samples and an increase in the amount of iron compounds treated. The surface morphology of the Fe-ACF/$TiO_2$ composites was characterized by means of SEM. The composites have a porous texture with homogenous compositions of Fe and titanium dioxide distributed on the sample surfaces. The phase formation and structural transition of the iron compounds and titanium dioxide were observed in X-ray diffraction patterns of the Fe-ACF/$TiO_2$ composites. The chemical composition of the Fe-ACF/$TiO_2$ composites, which was investigated with EDX shows strong peaks for the C, O, Fe and Ti elements. The photo degradation results confirm that the Fe-ACF/$TiO_2$ composites show excellent removal activity for the COD in piggery waste due to photocatalysis of the supported $TiO_2$, radical reaction by Fe species, and the adsorptivity and absorptivity of ACF.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.64.2-64.2
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• 2010

In order to improve the overall power conversion efficiency in dye-sensitized solar cells (DSSCs), it is very important to secure the sufficient surface area of photocatalytic nanoparticles layer for absorbing dye molecules. It is because increasing the amount of dye absorbed generally results in increasing the amount of light harvesting. In this work, we proposed a new method for increasing the specific surface area of photocatalytic titanium oxide ($TiO_2$) nanoparticles by using an inorganic templating method. Salt-$TiO_2$ composite nanoparticles were synthesized in this approach by spray pyrolyzing both the titanium butoxide and sodium chloride solution. After aqueous removal of salt from salt-$TiO_2$ composite nanoparticles, mesoporous $TiO_2$ nanoparticles with pore size of 2~50 nm were formed and then the specific surface area of resulting porous $TiO_2$ nanoparticle was measured by Brunauer-Emmett-Teller (BET) method. Generally, commercially available P-25 with the average primary size of ~25 nm $TiO_2$ nanoparticles was used as an active layer for dye-sensitized solarcells, and the specific surface area of P-25 was found to be ~50 $m^2/g$. On the other hand, the specific surface area of mesoporous $TiO_2$ nanoparticles prepared in this approach was found to be ~286 $m^2/g$, which is 5 times higher than that of P-25. The increased specific surface area of $TiO_2$ nanoparticles will absorb relatively more dye molecules, which can increase the short curcuit current (Jsc) in DSSCs. The influence of nanoporous structures of $TiO_2$ on the performance of DSSCs will be discussed in terms of the amount of dye molecules absorbed, the fill factor, the short circuit current, and the power conversion efficiency.