• Journal of Periodontal and Implant Science
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• v.37 no.2
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• pp.265-275
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• 2007

The present study was performed to evaluate the effect of Tetracycline-HCI on the change of implant surface microstructure according to application time. Implants with thermal dual acid etched surface were utilized. Implant surface was rubbed with $50mg/m{\ell}$ Tetracycline-HCI solution and sterilized saline for O.5min, 1min, 1.5min, 2min, 2.5min and 3min. respectively in the test group. Then, specimens were processed for scanning electron microscopic observation and measured surface roughness by optical interferometer. The results of this study were as follows. 1. The thermal dual acid etched surfaces showed many small peaks and valleys distributed overall surface. 2. The surface conditioning with Tetracycline-HCI and saline didn't influence on its micromorphology. In conclusion, the implant with thermal dual acid etched surface has a protective micromorphology from the detoxification with $50mg/m{\ell}$ Tetracycline-HCI and a scrubbing with cotton pellet. Therefore, the detoxification with $50mg/m{\ell}$ Tetracycline-HCI is an effective method for peri-implantitis in case implants with thermal dual acid etched surface.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.868-871
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• 2006

In-plane switching characteristics of PI rubbed ITO sandwich cell with low molecule FLC (ferroelectric liquid crystal) surface was investigated. FLC on the surface is governed by the applying frequency and surface condition. By controlling the Ps (spontaneous polarization) direction of dual FLC surfaces, switching characteristics are improved without change of cell structure.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.42-43
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• 2006

We have prepared random, block and graft copolymers with single or dual sensitivities to various stimuli. We have conjugated these polymers to proteins at random lysine sites or at specific sites designed into the protein by genetic engineering. We are also grafting the smart polymers to the surfaces of nanobeads. We are applying these smart conjugates and smart nanobeads in microfluidic devices for various applications, including diagnostics, affinity separations and enzyme bioprocesses. In this talk I will update our work with these interesting hybrid systems.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.3
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• pp.227-233
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• 2023

Tardive dyskinesia is an involuntary neurological movement disorder caused by long-term use of dopamine receptor-blocking drugs leading to dental implications like uncontrolled gnashing and grinding of teeth which in turn imperil the oral rehabilitation procedures as the excessive load increases the risk of prosthesis fracture. A 40-year male with a medical history of tardive dyskinesia visited the hospital to receive oral rehabilitation for missing maxillary anterior teeth. After the oral examination, tooth preparation was done on teeth 13, 15, and 23. After that silicon impression was made and the gypsum cast was digitalized using a desktop scanner and an interim prosthesis was fabricated by milling a resin block. During the try-in, the occlusal one-third of the interim prosthesis was trimmed, and an auto-polymerizing acrylic resin was applied on the occlusal surfaces and inserted in the patient's mouth. Then, the functionally generated path (FGP) of occluding surfaces of opposing arches was traced on the resin surface. When the resin was hardened, the modified interim prosthesis was removed and digitized using an intraoral scanner. The scan image was used in designing the occlusal morphology of definitive prosthesis by modifying the design of the interim prosthesis using the dual scan method. Lastly, a monolithic zirconia prosthesis was fabricated by milling a zirconia block. The definitive prosthesis was delivered reflecting the patient's occlusal scheme. This case report shows that the FGP technique with the dual scan method can help in fabricating fixed prosthesis with harmonious occlusion in a tardive dyskinesia patient.

• Journal of Periodontal and Implant Science
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• v.36 no.3
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• pp.731-744
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• 2006

The present study was performed to evaluate the effect of tetracycline-HCl on the change of implant surface microstructure according to application time. Implant with pure titanium machined surface, HA-coated surface and dual acid etched surface were utilized. Implant surface was rubbed with $50mg/m{\ell}$ tetracycline-HCL solution for ${\frac{1}{2}}$min., 1min., $1{\frac{1}{2}}$min., 2min., and $2{\frac{1}{2}}$min. respectively in the test group. Then, specimens were processed for scanning electron microscopic observation. The results of this study were as follows. 1. Both test and control group showed a few shallow grooves and ridges in pure titanium machined surface implants. There were not significant differences between two groups. 2. In HA-coated surfaces, round particles were deposited irregularly. The roughness of surfaces conditioned with tetracycline-HCL was lessened and the cracks were increased relative to the application time. 3. The etched surfaces showed the honey comb structures. The surface conditioning with tetracycline-HCI didn't influence on its micro-morphology. In conclusion, the detoxification with $50mg/m{\ell}$ tetracycline-HCI must be applied respectively with different time according to various implant surfaces.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.472-472
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• 2011

The capacitive coupled plasma (CCP) has been extensively used in the semiconductor industry because it has not only good uniformity, but also low electron temperature. But CCP source has some problems, such as difficulty in varying the ion bombardment energy separately, low plasma density, and high processing pressure, etc. In this reason, dual frequency CCP has been investigated with a separate substrate biasing to control the plasma parameters and to obtain high etch rate with high etch selectivity. Especially, in this study, we studied on the etching of $SiO_2$ by using the pulse-time modulation in the dual-frequency CCP source composed of 60 MHz/ 2 MHz rf power. By using the combination of high /low rf powers, the differences in the gas dissociation, plasma density, and etch characteristics were investigated. Also, as the size of the semiconductor device is decreased to nano-scale, the etching of contact hole which has nano-scale higher aspect ratio is required. For the nano-scale contact hole etching by using continuous plasma, several etch problems such as bowing, sidewall taper, twist, mask faceting, erosion, distortions etc. occurs. To resolve these problems, etching in low process pressure, more sidewall passivation by using fluorocarbon-based plasma with high carbon ratio, low temperature processing, charge effect breaking, power modulation are needed. Therefore, in this study, to resolve these problems, we used the pulse-time modulated dual-frequency CCP system. Pulse plasma is generated by periodical turning the RF power On and Off state. We measured the etch rate, etch selectivity and etch profile by using a step profilometer and SEM. Also the X-ray photoelectron spectroscopic analysis on the surfaces etched by different duty ratio conditions correlate with the results above.

• The Journal of Advanced Prosthodontics
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• v.5 no.2
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• pp.133-139
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• 2013

PURPOSE. This study was to evaluate the effect of the solution temperature on the mechanical properties of dualcure resin cements. MATERIALS AND METHODS. For the study, five dual-cure resin cements were chosen and light cured. To evaluate the effect of temperature on the specimens, the light-cured specimens were immersed in deionized water at three different temperatures (4, 37 and $60^{\circ}C$) for 7 days. The control specimens were aged in a $37^{\circ}C$ dry and dark chamber for 24 hours. The mechanical properties of the light-cured specimens were evaluated using the Vickers hardness test, three-point bending test, and compression test, respectively. Both flexural and compressive properties were evaluated using a universal testing machine. The data were analyzed using a two way ANOVA with Tukey test to perform multiple comparisons (${\alpha}$=0.05). RESULTS. After immersion, the specimens showed significantly different microhardness, flexural, and compressive properties compared to the control case regardless of solution temperatures. Depending on the resin brand, the microhardness difference between the top and bottom surfaces ranged approximately 3.3-12.2%. Among the specimens, BisCem and Calibra showed the highest and lowest decrease of flexural strength, respectively. Also, Calibra and Multilink Automix showed the highest and lowest decrease of compressive strength, respectively compared to the control case. CONCLUSION. The examined dual-cure resin cements had compatible flexural and compressive properties with most methacrylate-based composite resins and the underlying dentin regardless of solution temperature. However, the effect of the solution temperature on the mechanical properties was not consistent and depended more on the resin brand.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.1-11
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• 2022

In this study, an electric resistance dual-spot welding process using a copper electrode inserted in a heating electrode is suggested for the spot welding of AZ31 magnesium sheets. This spot-welding process involves two heating methods for welding at the interfacial zone between the magnesium sheets, one of which is the heating method by thermal conduction from the heating electrode heated by the welding current induced to the steel electrode, and the other heating method uses the electric resistance between the contacted surfaces of the two sheets by the welding current induced to the copper electrode. This welding process includes the welding variables, such as the current induced in the heating electrode and the copper electrode, and the outer diameters of the heating electrode. This is because the heat conducted from the heating electrode can be maintained at a higher temperature in the welding zone, which has a slow cooling effect on the nugget of the melted metal after the welding step. The pressure exerted during the pressing of the magnesium sheets by the heating electrode can be increased around the nugget zone at the spot-welding zone. Thus, it not only reduces the warping effect of the elastoplastic deformation of sheets, but also the corona bond can make it less prone to cracking at the welded zone, thereby reducing the number of nuggets expelled out of the corona bond. In conclusion, it was known that an electric resistance dual spot welding process using the copper electrode inserted in the heating electrode can improve the welding properties in the electric resistance spot welding process of AZ31 magnesium sheets.

• Korean Journal of Environmental Agriculture
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• v.22 no.3
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• pp.177-184
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• 2003

Although clay can sorb significant amounts of inorganic contaminants from soils and wastewater, the hydration of exchangeable cations in clay minerals makes it hydrophilic at the clay mineral surfaces and interlayers. Thus, natural clays are often ineffective in complexing and stabilizing toxic organic contaminants in soils and groundwater environment. But, substituting these hydrated cations with cationic surfactant such as QAC(Quaternary ammonium Compound) can change the natural clay from hydrophilic to hydropobic. Furthermore functionalized organoclay can act as a powerful dual function sorbent for both toxic metals and organic compounds. It also can be used as landfill clay liners, slurry walls, nano-composite materials, petroleum tank farms, waste treatment, and filter systems. To use this modified clay minerals effectively, it is required to understand the fundamental chemistry of organoclay, synthetic procedures, its engineering application, bioavailability of sorbed ion-clay complex, and potential risk of organoclay. In this review, we investigate the use, application and historical background of the organoclay in remediation technology. The state-of-the-art of organoclay research is also discussed. Finally, we suggest some future implications of organoclay in environmental research.

• Korean Journal of Optics and Photonics
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• v.26 no.3
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• pp.147-154
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• 2015

We propose a method for simultaneously measuring the front and back surface profiles of transparent optical components. The proposed method combines dual-wavelength transmission deflectometry with liquids to record distorted phases at different wavelengths, and then numerically reconstructs the three-dimensional phase information to image the front and back surfaces of the lens. We propose a theoretical model to determine the surface information, and a bifocal lens is experimentally investigated. Unlike conventional transmission deflectometry, our proposed method supports direct observation of the front and back surface profiles of the optical elements.