• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.618-624
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• 2002

Effect of the roasted barley tea in commercial markets on the adherence to the saliva-coated hydroxyapatite(HA) beads and the cell surface hydrophobicity of Streptococcus mutans and Streptococcus sobrinus as cariogenic microorganism was examined in vitro. Adherence activity and hydrophobicity in bacteria tested in all the barley tea samples decreased and the values were different according to the type of tea and the type of treatment. The inhibition of bacterial adsorption to HA beads suggest that barley tea active molecules as catechins and melanoidins may adsorb to a host surface, preventing the tooth receptor from interacting with any bacterial adhesions. The obtained results showed that the barley tea may inhibit bacterial adherence, the first step of the pathogenesis of dental caries in which these microorganism are involved.

• Molecular & Cellular Toxicology
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• v.3 no.1
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• pp.36-45
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• 2007

Several features of the implant surface, such as topography, roughness, and composition play a relevant role in implant integration with bone. This study was conducted in order to determine the effects of different-coatings on Ti surfaces on the biological responses of a human osteoblast-like cell line (MG63). MG63 cells were cultured on HA (Hydroxyapatite coating on Titanium), Ano (HA coating on anodized surface Titanium), Zr (zirconium-coating on Titanium), and control (non-coating on Titanium). The morphology of these cells was assessed by SEM. The cDNAs prepared from the total RNAs of the MG63 were hybridized into a human cDNA microarray (1,152 elements). The appearances of the surfaces observed by SEM were different on each of the three dental substrate types. MG63 cells cultured on HA, Ano, Zr, and control exhibited cell-matrix interactions. In the expression of several genes were up-, and down-regulated on the different surfaces. The attachment and expression of key osteogenic regulatory genes were enhanced by the surface morphology of the dental materials used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3269-3273
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• 2009

In this study, recycling methods of nano $TiO_2$-coated silica-bead were conducted in order to solve a deactivation problem of bead that had been invented for decomposition of pollutants in aqueous solution. Surface cleansing was selected as the recycling method for used beads. The surface cleansing was done with four different solutions such as distilled water, surfactant, acetone, and ethyl alcohol(ethanol). The recycling process consists of cleansing and calcination. After cleaning the used (deactivated) beads, calcination was done at $100^{\circ}C$, $200^{\circ}C$ and $300^{\circ}C$ for 30 minutes, respectively. This process was repeated three times. The activity of the recycled bead was measured by photo-degradation of methylene blue. The result shows that acetone cleansing and calcination at $100^{\circ}C$ for 30 minutes was the most efficient recycling method.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.422-426
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• 2008

Hemodialysis graft coated with paclitaxel prevents stenosis; however, large initial burst release of paclitaxel causes many negative effects such as drug toxicity and inefficient drug loss. Therefore we developed and tested a novel coating method, double dipping, to provide controlled and sustained release of paclitaxel locally. Expanded polytetrafluoroethylene (ePTFE) grafts were dipped twice into a solution of several different paclitaxel concentrations. In vitro release tests of the double dipping method showed that early burst release could be somewhat retarded and followed by sustained release for a long time. We observed the effect of paclitaxel coating by double dipping in porcine model of arterio-venous (AV) grafts between the common carotid artery and the external jugular vein. 12 weeks after constructing AV grafts, cross sections of the graft venous anastomosis were obtained and analyzed. Paclitaxel coated ePTFE grafts by double dipping were observed to prevent neointimal hyperplasia and therefore reduced stenosis of the arteriovenous hemodialysis grafts, especially at the graft venous anastomosis sites. Our results demonstrate that second dipping of ePTFE graft, which was already coated once with paclitaxel, washes off the drug on a surface of the graft and affects the ratio of paclitaxel on the surface to that of the inner space, possibly by diffusion: thus the early burst of drug can be somewhat reduced.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.282-283
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• 2005

Ion beam assisted deposition(IBAD) technique was used to produce biaxially textured polycrystalline MgO thin films for high critical current YBCO coated conductor. Hastelloy tapes were continuous electropolished with very smooth surface for IBAD-MgO deposition, RMS roughness of Hastelloy tape values below 2 nm and local slope of less than $1^{\circ}$. After the polishing of the tape an amorphous $Y_2O_3$ and $Al_2O_3$ are deposited Biaxially textured MgO was deposited on amorphous layer bye-beam evaporation with a simultaneous bombardment of high energy ions. We had developed the RHEED to measure in-situ biaxial texture of film surface as thin as tens angstrom. And also ex-situ characterization of buffer layers was studied using XRD and SEM. The full-width at half maximum(FWHM) out of plane texture of IBAD-MgO template is $4^{\circ}$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.3
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• pp.83-89
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• 2004

In this work, HA/$TiO_2$ biocomposite to get high mechanical properties with biocompatibility were prepared. HA/$TiO_2$ biocomposite powders were prepared by mixing $TiO_2$ and HA powders which were synthesized through sol-gel, precipitation and hydrothermal methods. The mixing ratio was fixed at 1:1 ratio (HA/$TiO_2$, wt%). HA/$TiO_2$ biocomposite powders showed different microstructures depending on their particle size and shape. The smaller particles were coated on the surface of larger particles, whereas they were well mixed and dispersed when both $TiO_2$ and HA were nanocrystallites. HA/$TiO_2$ biocomposite powders with homogeneous microstructure showed high sintered density and good mechanical properties.

• Progress in Superconductivity
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• v.6 no.1
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• pp.74-78
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• 2004

YBCO coated conductor is one of the most promising materials as a new generations wire especially for practical power applications. In this work, $YBa_2$$Cu_3$$O_{7}$ -$\delta$/(YBCO) coated conductors (CC) were deposited by pulsed laser deposition (PLD) from buffer layers to superconducting layer on hi-axially textured metal tape. The oxide multilayer buffered substrate of architectures of $CeO_2$/$YSZ/Y_2$$O_3$ was fabricated by PLD at steady status. Then YBCO layer was deposited on RABiTS substrate by stationary and reel-to-reel (R2R) continuous process and we compared with deposition conditions of both processes. The degree of texture of each layer was investigated using X-ray diffraction including $\theta$-2$\theta$ scans, $\omega$-scans and $\Phi$-scans analysis. Their surface morphology was observed by scanning electron microscopy (SEM). The FWHM of the X-ray $\Phi$-scans and $\Phi$-scans indicated that YBCO and buffer layers closely replicate the in-plane and out-of-plane texture of metal tape. Critical current (Ic) at 77 K, self-field of 75.8 A/cm-width, critical temperature (Tc) of 85 K, and critical current density (Ic) of 3.7 MA/$\textrm{cm}^2$ were measured from coated conductor deposited by stationary process. And coated conductor deposited by R2R continuous process had Ic of 57.5 A/cm-width, Tc of 86.5 K and Jc of 2.0 MA/$\textrm{cm}^2$. The film also exhibits a homogeneous and dense surface morphology.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.1
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• pp.78-94
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• 2005

Purpose. The purpose of this study was to compare the effects of various surface treatments by measuring resonance frequency and histomorphometric analyses. Material and methods. In 5 adult dogs, the mandibular premolar were extracted. Six months later, 30 screw titanium implants (Dentium Co., Seoul, Korea) 6mm in length and 3.4mm in diameter, were placed in the mandibles of 5 dogs. Implants were divided into five groups following to surface treatment methods ; Group 1 is machined controls, Group 2 is sandblasted with large grit and acid-etched (SLA), Group 3 is anodized (Autoelectric Co., Korea, 660Hz, Duty10), Group 4 is hydroxyapatite(HA) coated by ion beam assisted deposition(E-beam), Group 5 is hydroxyapatite(HA) coated with Sol-gel coating process. Resonance frequency was measured implant placement immediately, and 3, 6 weeks and 10 weeks of healing perods. With the animal subject's sacrifice 10 weeks after implantation, implants were removed on bloc and histologic and computer-based histomorphometric analyses were performed. Histomorphometric analysis involved quantification of the entire bone to metal contact around the implants. Statistical analyses were performed using the SPSS for Windows (ver. 9.0 SPSS Inc.) Statistical differences were considered significant at P<0.05. Results. The results were as follows : 1) In five groups, mean value of resonance frequency analysis(RFA) were highest in group 5 (Sol-gel implant) at implantation and those of group 4 (E-beam)was highest at 10 weeks . but there was no correlation between surface treatments and RFA. 2) In all surface treatment groups, the RFA values of implants decreased until 3 weeks and increased to 10 weeks. 3) The percentage of direct bone-to-implant contact (BIC) had statistical significance between five groups in cancellous bone, (P<0.05) the percentage of bone density inside the thread had no statistical significance between five groups. (P>0.05) 4) There was a significant difference between cortical bone and cancellous bone in BIC. (P<0.05) and bone density. (P<0.05) 5) There was a correlation between the RFA value of implants at 10 weeks and BIC in cancellous bone, and between the RFA value of implants at 10 weeks and bone density in cortical bone. (P<0.05). Conclusions. These results indicate that surface treatment does not affect the implant stability in case of good bone quality.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.267-284
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• 1991

Since the concept of a direct contact between bone and implants, without interposed soft- tissue layers, was reported by Dr. $Br{\aa}nemark$, there has been increasing necessity for correct under-standing of bone-implant interface and surrounding tissue response. Beside quality of bone, surgical technique, load applied to implants, one must consider implant materials, design and surface characteristics to obtain osseointegration. In this study HA plasma-sprayed implants, TPS implants and $Al_2O_3$ implants were inserted into the alveolar bone of dog and tissue response was observed with radiograph, stereoscope, light microscope, and scanning electron microscope. Results were as follows : 1. There was rapid and active bone formation in the region adjacent to HA plasma-sprayed implants but in the deep supporting bone only slight bone formation was seen. 2. There was considerable lamella bone formation in the region adjacent to TPS implants and the deep supporting bone became more compact. 3. There was some gap and sclerosing bone formation in the adjacent region of $Al_2O_3$ implants, but there was irregular new bone formation in the deep supporting bone. Therefore, it seems that $Al_2O_3$ is not adequate for osseointegrated implants.

• Journal of Adhesion and Interface
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• v.25 no.2
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• pp.63-68
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• 2024

In this study, the contamination of gold(Au) wire according to the types of rinse applied for surface treatment in the wire bonding process is investigated and confirmed. For the surface treatment, rinses containing silicon(Si) or those based on organic materials are mainly employed. To identify their effects, surface treatment is conducted on Au wire using two types of rinse at a 1.0 wt% concentration, referred to as Si-including and Oil-based rinse-coated Au wire. Subsequently, a simulation experiment is performed to verify the reactivity of dust containing Si components that could occur in the semiconductor process. Through optical microscopy (OM) and scanning electron microscopy(SEM) analysis, it is observed that a larger amount of dust is adsorbed on the surface of Si-including rinse-coated Au wire compared with the Oil-based rinse-coated Au wire. This is attributed that the rinse containing Si components is relatively polar, causing polar interactions with dust, which also has polarity. Therefore, it is expected that using a rinse without Si components can reduce contamination caused by dust, thereby decreasing the defect rate in the practical wire bonding process.