• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1065-1068
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• 2008

Marine bridges are readily deteriorated due to the exposure to marine environment. The concrete deterioration occurred by corrosion of steel in concrete is mainly relevant to chloride in seawater. Chloride ions penetrate through porous concrete, and then reach to the reinforcing steel, and finally corroded them. The corrosion by-products(rusts) increase the volume as much as 6 to 10 times of origin steel. this creates expanding pressure and tensile stress, which cause the structures cracking and spalling. Sometimes the rebar corrosion is accelerated, and then collapsed catastrophically. In order to prevent corrosion damage, it is important to understand well regarding the reason of concrete corrosion, the quantification of its damage, and protection method/system to stop or to mitigate the corrosion. In this study, slab specimens were fabricated to evaluate the effect of cathodic protection which was simulated to marine bridges, and/or port structures. Zn-mesh sacrificial anode has been applied as a chathodic protection system and accelerated test conditions, i.e. temperature and salt concentration have been used in this study.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.337-349
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• 2008

Despite an improved bone reactions of Mg-incorporated implants in the animals, little yet has been carried out by the experimental investigations in functional loading conditions. This study investigated the clinical and histologic parameters of osseointegrated Mg-incorporated implants in delayed loading conditions. A total of 36 solid screw implants (diameter 3.75 mm, length 10mm) were placed in the mandibles of 6 beagle dogs. Test groups included 18 Mg-incorporated implants. Turned titanium Implants served as control. Gold crowns were inserted 3 months. Radiographic assessments and stabilitytests were performed at the time of fixture installation, $2^{nd}$ stage surgery, 1 and 3 months after loading. Histological observations and morphometrical measurements were also performed. Of 36 implants, 32 displayed no discernible mobility, corresponding to successful clinical function. There was no statistically significant difference between test implants and controls in marginal bone levels (p=0.413) and RFA values. The mean BIC % in the Mg-implants was $54.4{\pm}20.2%$. The mean BIC % in the turned implant was $48.9{\pm}8.0%$. These differences between the Mg-implant and control implant were not statistically significant (P=0.264). In the limitation of this study, bone-to-implant contact (BIC) and bone area of Mg-incorporated oxidized implant were similar to machine-turned implant. The stability analysis showed no significantly different ISQ values and marginal bone loss between two groups. Considering time-dependent bone responses of Mg-implant, it seems that Mg-implants enhanced bone responses in early loading conditions and osseointegrated similarly to cp Ti implants in delayed loading conditions. However, further investigations are necessary to obtain long-term bone response of the Mg-implant in human.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.4
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• pp.298-304
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• 2014

Purpose: This preliminary rabbit study was conducted to evaluate the effect of recombinant human transforming growth factor-${\beta}2$ (rhTGF-${\beta}2$)/poly lactic-co-glycolic acid (PLGA) coating on osseointegration of the titanium (Ti) implant. Materials and methods: Eight Ti implants were anodized with 300 voltages for three minutes. Four of those were coated with rhTGF-${\beta}2$/PLGA by an electrospray method as the experimental group. The implants were placed into tibiae of four New Zealand rabbits, two implants per a tibia, one implant per each group. After 3 and 6 weeks, every two rabbits were sacrificed and micro-computed tomography (microCT) was taken for histomorphometric analysis. Results: In scanning electron microscope (SEM) image, the surface of rhTGF-${\beta}2$/PLGA coated Ti implant showed well distributed particles. Although statistically insignificant, microCT analysis showed that experimental group has higher bone volume / total volume (BV/TV) and trabecular thickness (Tb.Th) values relatively. Cross sectional view also showed more newly formed bone in the experimental group. Conclusion: In the limitation of this study, rhTGF-${\beta}2$/PLGA particles coating on the Ti implant show the possibility of more favorable quantity of newly formed bone after implant installation.

• Resources Recycling
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• v.26 no.2
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• pp.56-65
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• 2017

This study is an experimental study on the corrosion protection performance according to the configuration ratio of the Zn and Al. A metal spraying was used as the arc metal spraying method, a specimen was produced by varying the proportion ratio and coating thickness of the Zn and Al. Experimental methods visually observed to corrosion of the specimen for 1, 3, 7, 15 days was conducted in accordance with the CASS salt spray test. This study has confirmed that the performance of the corrosion protection improved against the increase in the Al content. Further, it was confirmed that excellent perfomance is exhibited when the coating thickness is secured over $80{\mu}m$. In addition, the SEM analysis was performed to observe the cross-sectional shape of the metal spraying specimen after CASS testing. The analysis result showed that the deterioration of the metal spraying coating layer was reduced as the Al content increases.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.1
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• pp.9-17
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• 2014

Purpose: The purpose of this study was to compare zirconia implants with titanium implants from the view point of biomechanical stability and histologic response on osseointegration when those were placed with xenograft materials. Materials and methods: Specimens were divided into two groups; the control group was experimented with eighteen titanium implants which had anodized surface and the experimental group was experimented with eighteen sandblasted zirconia (Y-TZP) implants. At the tibias of six pigs, implants were installed into bone defect sites prepared surgically and treated with resorbable membranes and bovine bone. Two pigs were sacrificed after 1, 4 and 12 weeks respectively. Each implant site was sampled and processed for histologic and histomorphometric analysis. The stability of implants was evaluated with a $Periotest^{(R)}$. And the interfaces between bone and the implant were observed with a scanning electron microscope. Results: In stability analysis there was no significant difference between Periotest values of the control group and the experimental group. In histologic analysis with a light microscope after 4 weeks, there was new bone formation with the resorption of bovine bone and the active synthesis of osteoblasts in both groups. In bone-implant contact percentage there was significant difference between both groups (P<.05). In bone area percentage there was no significant difference between both groups. In analysis of both groups with a scanning electron microscope there was a gap between bone and a surface at 4 weeks and it was filled up with bone formed newly at 12 weeks. Conclusion: When accompanied by xenograft using membrane, bone to implant contact percentage of zirconia implants used in this experiment was significantly less than that of the titanium implants by surface treatment of anodic oxidation. So, it is considered that the improvement of zirconia implant is needed through ongoing research on surface treatment methods for its practical use.