• Journal of Environmental Science International
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• v.17 no.9
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• pp.1023-1032
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• 2008

The feasibility study of the application of the photoelectrocatalytic and electrolytic/UV decolorization of Rhodamine B (RhB) was investigated in the photoelectrocatalytic and electrolytic/UV process with $TiO_2$ photoelectrode and DSA (dimensionally stable anode) electrode. Three types of $TiO_2$ photoelectrode were used. Thermal oxidation electrode (Th-$TiO_2$) was made by oxidation of titanium metal sheet; sol-gel electrode (5G-$TiO_2$) and powder electrode (P-$TiO_2$) were made by coating and then heating a layer of titania sol-gel and slurry $TiO_2$ on titanium sheet. DSA electrodes were Ti and Ru/Ti electrode. The relative performance for RhB decolorization of each of the photoelecoodes and DSA electrodes is: Ru/Ti > Ti > SG-$TiO_2$ > Th-$TiO_2$. It was observed that photoelectrocatalytic decolorization of RhB is similar to the sum of the photocatalytic and electrolytic decolorization. Therefore the synergetic effect was not showed in pthotoelectrocatalytic reaction. $Na_{2}SO_{4}$ and NaCl showed different decolorization effect between pthotoelectrocatalytic and electrolytic/UV reaction. In the presence of the NaCl, RhB decolorization of Ru/Ti DSA electrode was higher than that of the other photoelectrode and Ti electrode. Optimum current, NaCl dosage and UV lamp power of the electrolytic/UV process (using Ru/Ti electrode) were 0.75 A, 0.5 g/L and 16 W, respectively.

• Archives of Plastic Surgery
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• v.41 no.4
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• pp.362-365
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• 2014

Background Many implants are being used for the reconstruction of orbital wall fractures. The effect of the choice of implant for the reconstruction of an orbital wall fracture on the surgical outcome is under debate. The purpose of this article is to compare the outcomes of orbital wall reconstruction of small orbital wall fractures on the basis of the implants used. Methods The authors conducted a retrospective study using electronic databases. Between March 2001 and December 2012, 461 patients with orbital wall fractures were included in this study. Among them, 431 patients in whom the fracture size was less than $300mm^2$ were analyzed. The fracture size was calculated using computed tomography scans of the orbit in the sagittal and coronal images. Cases in which the fracture size was less than $300mm^2$ were included in this study. Results One hundred and twenty-nine patients were treated with silastic sheets; 238 patients were treated with titanium meshes; and absorbable meshes were used in the case of 64 patients. Overall, 13 patients required revision, and the revision rate was 3.0%. The revision rate of the silastic sheet group was 5.4%. In the multivariable analysis, the revision rate of the group reconstructed with silastic sheets was highly statistically significant (P=0.043, odds ratio=3.65). However, other factors such as age, sex, fracture type, and fracture size were not significant. Conclusions Reconstruction of orbital wall fractures with silastic sheets may cause more complications than that with other materials such as titanium meshes and absorbable meshes.

• Journal of Welding and Joining
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• v.34 no.6
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• pp.62-68
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• 2016

Laser welding has superior characteristic such as low distortion, high welding speed, easy automation and real time control. But it is easy to occur weld defects such as porosity, crater, humping bead in the area of welding start and end. These weld defects can be suppressed by applying the wave shape control. In this study CW fiber laser was used for welding of $0.5mm^t$ pure titanium. Penetration properties were evaluated with the time of slope up and down. After then the bead shape was observed, and the maximum depth and the area of crater were measured. The bead shape of welding start area changed to be sharp with increase of slope up time and non-weld area of welding start increased. The crater and humping bead were suppressed with slope down time. The cooling rate of crater area was understood through measure of the hardness. Also, The distribution tendency of alloying elements was observed by EPMA and EDS. When wave shape control didn't applied to weld, the hardness of end weld increased due to rapid cooling rate and the hardness of rear part in the crater was higher than that of fore part. On the other hand, when the wave shape control was used for end weld, the increase of hardness in the end weld couldn't be found due to gradual cooling rate.

• Journal of Periodontal and Implant Science
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• v.52 no.3
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• pp.242-257
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• 2022

Purpose: This study investigated periodontal ligament (PDL) restoration in osseointegrated implants using stem cells. Methods: Commercial pure titanium and zirconium oxide (zirconia) were coated with beta-tricalcium phosphate (β-TCP) using a long-pulse Nd:YAG laser (1,064 nm). Isolated bone marrow mesenchymal cells (BMMSCs) from rabbit tibia and femur, isolated PDL stem cells (PDLSCs) from the lower right incisor, and co-cultured BMMSCs and PDLSCs were tested for periostin markers using an immunofluorescent assay. Implants with 3D-engineered tissue were implanted into the lower right central incisors after extraction from rabbits. Forty implants (Ti or zirconia) were subdivided according to the duration of implantation (healing period: 45 or 90 days). Each subgroup (20 implants) was subdivided into 4 groups (without cells, PDLSC sheets, BMMSC sheets, and co-culture cell sheets). All groups underwent histological testing involving haematoxylin and eosin staining and immunohistochemistry, stereoscopic analysis to measure the PDL width, and field emission scanning electron microscopy (FESEM). The natural lower central incisors were used as controls. Results: The BMMSCs co-cultured with PDLSCs generated a well-formed PDL tissue that exhibited positive periostin expression. Histological analysis showed that the implantation of coated (Ti and zirconia) dental implants without a cell sheet resulted in a well-osseointegrated implant at both healing intervals, which was confirmed with FESEM analysis and negative periostin expression. The mesenchymal tissue structured from PDLSCs only or co-cultured (BMMSCs and PDLSCs) could form a natural periodontal tissue with no significant difference between Ti and zirconia implants, consequently forming a biohybrid dental implant. Green fluorescence for periostin was clearly detected around the biohybrid implants after 45 and 90 days. FESEM showed the invasion of PDL-like fibres perpendicular to the cementum of the bio-hybrid implants. Conclusions: β-TCP-coated (Ti and zirconia) implants generated periodontal tissue and formed biohybrid implants when mesenchymal-tissue-layered cell sheets were isolated from PDLSCs alone or co-cultured BMMSCs and PDLSCs.

• Transactions of Materials Processing
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• v.26 no.6
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• pp.348-355
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• 2017

In recent years, dissimilar materials such as aluminum, magnesium, titanium, and advanced high strength steel are widely used in automotive body due to environment concerns and fuel consumption. Therefore, joining technology is important for assembling components made of dissimilar materials. In this study, friction stir hole clinching (FSHC) was proposed as a new mechanical joining method to join dissimilar materials. This process stirs and heats the upper sheet, forming mechanical interlocking with the lower sheet. The feasibility of this FSHC process was verified by comparing cross-section of joint in FSHC and hole clinching process under the same processing condition. Taguchi method was also applied to the FSHC process to estimate the effect of process parameters on joint strength and obtain optimal combination of process parameters. Joint strength of FSHC with optimal process condition was compared to that of FSHC with initial process condition as well as that of hole clinching with optimal process condition. Results showed that the FSHC process was useful for joining dissimilar materials, even if the formability of materials was low.

• Journal of the Korea Convergence Society
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• v.8 no.4
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• pp.199-205
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• 2017

In this study, the design analysis and the explosion welding were made into a clad sheet by the convergence method in order to solve the problem of heat transfer to the guide due to the heating of the 3D printer heating block. The shear strength of the clad plate material was tested and the results were analyzed by thermal analysis, thermal conductivity and thermal imaging. The following conclusions were obtained. 3D modeling of the heating block made of copper and titanium clad plate material The thermal analysis showed that the surface temperature of the filament guide area was lower than the heating block surface temperature. The average shear strength of copper and titanium clad plate material was measured and the average value of 195.6MPa was obtained. The thermal conductivity of the heating block made of copper and titanium clad plate material was measured three times and the average value was $62.52W/m{\cdot}K$. The surface temperature of the heating block made of copper and titanium clad plate material was measured by a thermal imaging camera at a maximum of $107.3^{\circ}C$ and $183.2^{\circ}C$ at the filament guide. The temperature distribution was $89^{\circ}C$ lower than that of the existing filament.

• Nuclear Engineering and Technology
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• v.25 no.4
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• pp.507-514
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• 1993

Titanium tubes have recently been used in condensers of nuclear power plants since titanium has very good corrosion resistance to seawater. However, when it is connected to Cu alloys as tube sheet materials and these Cu alloys are connected to carbon steels as water box materials, it makes significant galvanic corrosion on connected materials. It is expected from electrochemical tests that the corrosion rate of carbon steel will increase when it is galvanically coupled with Ti or Cu in sea water and the corrosion rate of Cu will increase when it is coupled with Ti, if this couple is exposed to sea water for a long time. It is also expected that the surface area ratios, R$_1$(surface area of carbon steel/surface area of Ti) and R$_2$(surface area of carbon steel/surface area of Cu) are very important for the galvanic corrosion of carbon steel and that these should not be kept to low values in order to minimize the galvanic corrosion on the carbon steel of the water box. Immersed galvanic corrosion tests show that the corrosion rate of carbon steel is 4.4 mpy when the ratio of surface area of Fe/ surface area of Al Brass is 1 while it is 570 mpy when this ratio is 10$^{-2}$ . The galvanic corrosion rate of this carbon steel is increased from 4.4 mpy to 13 mpy at this area ratio, 1, when this connected galvanic specimen is galvanically coupled with a Ti tube. This can be rationalized by the combined effects of R$_1$ and R$_2$ on the polarization curve.

• Archives of Craniofacial Surgery
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• v.14 no.1
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• pp.30-35
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• 2013

Background: For reconstruction of the mild to moderate medial orbital wall fractures, various surgical approaches have been used. Prior existing W-shaped incision was a direct local approach through a 3 cm incision on the superior medial orbital area with a titanium mesh implant. In this study, the authors modified W-shaped incision and reconstructed the defect with silastic sheet to improve the result and the postoperative scar. Methods: This study included 20 patients who had mild to moderate size of medial wall defect and therefore relatively suitable for reconstruction with silastic sheets from July, 2009 to December, 2011. A modified W-shaped skin incision approximately 1.2 to 1.5 cm in length was made along the superior medial orbital rim from approximately 1 cm medial to the medial canthus to the lower border of the medial eyebrow. The angles of the limbs of the W ranged from 150 to 160 degrees. Results: By using soft flexible silastic sheet, the authors reduced the incision from 3 to 1.5 cm, and by widening the angle of the W limbs, scars were more effectively hided in the relaxed skin tension line. Scar assessment was done with modified patient and observer scar assessment scale and mean score from patients was 2.08 and mean score from observers was 2.12. Conclusion: Although this method will not be suitable for every case, it can be a consistent method to obtain the surgical goal in treatment of mild to moderate blowout fractures of the medial orbital wall.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.328-331
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• 2009

Microstructural evolution of alpha and beta phases during dynamic globularization of near-beta Ti-13Nb-13Zr alloy was investigated to determine the optimum processing conditions. The submicrocrystalline alloy sheet with ${\sim}80%$ of high-angle grain boundaries was produced utilizing dynamic globularization at temperature of $600^{\circ}C$, equivalent strain rate of $10^{-1}\;s^{-1}$ and strain of 1.4. The refined structure with the gain size of ${\sim}0.4{\mu}m$ showed 25-60% enhanced mechanical compatibility as compared to those of the conventional mill-annealed or solution treated and aged microstructures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.1039-1042
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• 2001

A method for designing antireflection (AR) and antistatic (AS) films by the use of conducting polymer as an electrically conductive transparent layer is proposed. The conducting AR film is composed of four-layer with alternating high and low refractive index layer: silicon dioxide (n=1.44) and titanium dioxide (n=2.02) prepared at low temperature by sol-gel method are used as the low and high refractive index layer, respectively. The 3,4-polyethylenedioxythiophene (PEDOT) which has the sheet resistance of 10$^4$$\Omega$/$\square$ is used as a conductive layer. Optical constant of ARAS film was measured by the spectroscopic ellipsometer and from the measured optical constants the spectral properties such as reflectance and transmittance were simulated in the visible region. The reflectance of ARAS films on glass substrate was below 0.8 %R and the transmittance was higher than 95 % in the visible wavelength (400-700 nm). The measured AR spectral properties was very similar to its simulated results.