• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.635-641
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• 1996

This study was designed to evaluate the anti cariogenic effect of F in primers, bonding agents, composite resins or glass ionomer cements in enamel. Twenty-five extracted teeth were selected and a cavity was prepared on either the buccal or the lingual surface of each tooth. After pumicing and etching, the samples were divided into 5 groups. In group A, the samples were primed, bonded and filled with ART bond and Brilliant Enamel (Coltene, Switzerland). Group B composed of Optibond and Herculited XRV (Kerr, USA), group C composed of Syntac and Tetric(Vivadent, Lichtenstein), and group D composed of Scotch-bond Multipurpose and Z 100 (3M, YSA). In group E, the samples were filled with glass ionomer cement (Fuji II LC, Japan), All surfaces except the 2mm beyond the cavosurface margin of the sample were protected, and samples were then put into an acid buffer for 3 days to develop the initial caries. The samples were then sectioned through the filling body into thin wafers and then examined with a polarizing microscope under water imbibition. The fluoride in primer, bonding agent, or composite filling material did not prevent the initial caries in the enamel area adjacent to the filling body whereas the fluoride in the glass ionomer did prevent the initial stage caries.

• Design & Manufacturing
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• v.17 no.1
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• pp.40-47
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• 2023

Macular degeneration and glaucoma are representative age-related retinal diseases that rank second and third in the prevalence of retinal diseases, and are a kind of degenerative neurological disease. Irreversible visual acuity and visual field damage may occur, and the number of patients is rapidly increasing as the population ages. Since this retinal disease is a chronic disease, continuous drug treatment is required. There are various drug delivery methods for treatment, but direct injection of the drug into the intravitreal is the most effective for continuous delivery of the drug over a long period of time. In order to solidify Dexamethasone, a retinal disease treatment, and insert it into the primary intravitreal, it is important to develop a technology to miniaturize the treatment and an applicator to deliver the treatment. In this study, a mold technology was developed to integrate the cannula and hub, which are one part of applicator. In addition, surface treatment was performed on the outside of the cannula to improve the bonding strength between the cannula and the hub, and the bonding strength according to each condition was analyzed through a tensile test.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.185-194
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• 2000

Rapid Prototyping(RP) techniques have their unique characteristics according to the working principles: stair-stepped surface of parts due to layer-by-layer stacking, low build speed caused by line-by-line solidification to build one layer, and additional post processing to improve surface roughness, so it is required very high cost to introduce and to maintain of RP apparatus. The objective of this study is to develop a new RP process, Variable Lamination Manufacturing using linear hotwire cutting technique and expandable polystyrene foam sheet as part material(VLM-S), and to investigate characteristics of part material, cutting characteristics by using linear hotwire cutting system and bonding. Experiments were carried out to investigate mechanical properties of part material such as anisotropy and directional tensile strength. In order to obtain optimal dimensional accuracy, surface roughness, and reduced cutting time, addition experiments were performed to find the relationship between cutting speed and cutting offset of hotwire, and heat generation of hotwire per unit length. So, adhesion strength tests according to ASTM test procedure showed that delamination did not occur at bonded area. Based on the data, a clover-shape was fabricated using unit shape part(USP) it is generated hotwire cutting. The results of present study have been reflected on the enhancement of the VLM-S process and apparatus.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.42-42
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• 2008

Considerable attention has been focused on the applications of flexible liquid crystal (LC)-based displays because of their many potential advantages, such as portability, durability, light weight, thin packaging, flexibility, and low power consumption. To develop flexible LCDs that are capable of delivering high-quality moving images, like conventional glass-substrate LCDs, the LC device structure must have a stable alignment layer of LC molecules, concurrently support uniform cell gaps, and tightly bind two flexible substrates under external tension. However, stable LC molecular alignment has not been achieved because of the layerless LC alignment, and consequently high-quality images cannot be guaranteed. To solve these critical problems, we have proposed a PDMS pixel-wall based bonding method via the IB irradiation was developed for fasten the two substrates together strongly and maintain uniform cell gaps. The effect of the IB irradiation on PDMS with PI surface was also evaluated by side structure configuration and a result of x-ray photoelectron spectroscopic analysis of PDMS interlayer as a function of binder with substrates. large number of PDMS pixel-walls are tightly fastened to the surface of each flexible substrate and could maintain a constant cell gap between the LC molecules without using any other epoxy or polymer. To enhance the electro-optical performance of the LC device, we applied an alignment method that creates pretilt angle on the PI surface via ion beam irradiation. Using this approach, our flexible LCDs have a contrast ratio of 132:1 and a response time of about 15 ms, resulting in highly reliable electro-optical performance in the bent state, comparable to that of glass-substrate LCDs.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.4
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• pp.685-692
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• 1995

The effect of five different surface treatments on the shear bond strength of the resin bond to Type IV Gold alloy was studied by bonding resin to metal. The metal surface was subjected to one of the following treatments and bonded ;(1) air abraded with $50{\mu}m$ alumina particles,(2) beads(3) beads and tin-plated at curreant density of 300mA/$cm^2$,(4) tin-plated at current density of 300mA/$cm^2$,(5) silicacoating with sililink, and bonded with an MDP Opaque primer, CESEAD resin system. The bonded specimens were immersed in water for 23 hours after 1 hour resin curing and shear bond strength were recorded. On the basis of this study, the following conclusions can be drawn; 1. Difference were found in the shear bond strength among all experimental groups. And bead glroup exihibited the highest shear bond strength and sand blasting group exhibited the lowest shear bond strength on five groups. 2. Bead group, mechanical bonding was significantly higher than that obtained with the samples, tinplating, silicacoating, and chemical bonding. 3. No statistically signiflcant difference was found between the shear bond strengths obtained with bead and bead-tinplating, and between tinplating and sili cacoating.

• Restorative Dentistry and Endodontics
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• v.41 no.2
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• pp.106-113
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• 2016

Objectives: This study evaluated the effects of different surface conditioning methods on the bond strength of orthodontic brackets to glazed full-zirconia surfaces. Materials and Methods: Glazed zirconia (except for the control, Zirkonzahn Prettau) disc surfaces were pre-treated: PO (control), polishing; BR, bur roughening; PP, cleaning with a prophy cup and pumice; HF, hydrofluoric acid etching; AA, air abrasion with aluminum oxide; CJ, CoJet-Sand. The surfaces were examined using profilometry, scanning electron microscopy, and electron dispersive spectroscopy. A zirconia primer (Z-Prime Plus, Z) or a silane primer (Monobond-S, S) was then applied to the surfaces, yielding 7 groups (PO-Z, BR-Z, PP-S, HF-S, AA-S, AA-Z, and CJ-S). Metal bracket-bonded specimens were stored in water for 24 hr at $37^{\circ}C$, and thermocycled for 1,000 cycles. Their bond strengths were measured using the wire loop method (n = 10). Results: Except for BR, the surface pre-treatments failed to expose the zirconia substructure. A significant difference in bond strengths was found between AA-Z ($4.60{\pm}1.08MPa$) and all other groups ($13.38{\pm}2.57-15.78{\pm}2.39MPa$, p < 0.05). For AA-Z, most of the adhesive remained on the bracket. Conclusions: For bracket bonding to glazed zirconia, a simple application of silane to the cleaned surface is recommended. A zirconia primer should be used only when the zirconia substructure is definitely exposed.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.63-69
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• 2019

Soldering technology has been used in electronic industry for a long time. However, due to solder fatigue characteristics, automotive electronics are searching the semi-permanent interconnection technology such as press-fit method. Press fit interconnection is a joining technology that mechanically inserts a press fit metal terminal into a through hole in a board, and induces a strong bonding by closely contacting the inner surface joining of the through hole by plastic deformation of press-fit terminal. In this paper, the bonding properties of press-fit interconnection are investigated with PCB hole size and surface finishes. In order to compare interconnection reliability between the press fit and soldering, the change in resistance of the press-fit and soldering joints was observed during thermal shock test. After thermal cycling, the failure modes are investigated to reveal the degradation mechanism both press-fit and soldering technology.

• Restorative Dentistry and Endodontics
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• v.46 no.4
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• pp.54.1-54.10
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• 2021

Objectives: The purpose of this study was to quantify phase transformation after hydrofluoric acid (HF) etching at various concentrations on the surface of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), and to evaluate changes in bonding strength before and after thermal cycling. Materials and Methods: A group whose Y-TZP surface was treated with tribochemical silica abrasion (TS) was used as the control. Y-TZP specimens from each experimental group were etched with 5%, 10%, 20%, and 40% HF solutions at room temperature for 10 minutes. First, to quantify the phase transformation, Y-TZP specimens (n = 5) treated with TS, 5%, 10%, 20% and 40% HF solutions were subjected to X-ray diffraction. Second, to evaluate the change in bond strength before and after thermal cycling, zirconia primer and MDP-containing resin cement were sequentially applied to the Y-TZP specimen. After 5,000 thermal cycles for half of the Y-TZP specimens, shear bond strength was measured for all experimental groups (n = 10). Results: The monoclinic phase content in the 40% HF-treated group was higher than that of the 5%, 10%, and 20% HF-treated groups, but lower than that of TS-treated group (p < 0.05). The 40% HF-treated group showed significantly higher bonding strength than the TS, 5%, and 10% HF-treated groups, even after thermal cycling (p < 0.05). Conclusions: Through this experiment, the group treated with SiO₂ containing air-borne abrasion on the Y-TZP surface showed higher phase transformation and higher reduction in bonding strength after thermal cycling compared to the group treated with high concentration HF.

• Journal of Technologic Dentistry
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• v.37 no.3
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• pp.121-127
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• 2015

Purpose: This study was intended to investigate the effect of applying liner for chemical bonding and physical surface roughness created on zirconia by using a sandpaper before sintering on the bond strength between the two materials. Methods: Zirconia blocks were cut using a low-speed cutter. Plate-shaped specimen($6mm{\times}6mm{\times}3mm$) was fabricated by sintering after giving surface roughness according to four kinds of sandpapers. Depending on whether or not to use liner, 60 specimens were divided into two groups ZN(non-liner), ZL(liner), and the two groups were subdivided into four groups respectively in accordance with sandpaper used, totaling eight groups (n=10). The surface roughness (Ra) values and shapes before sintering were observed, and shear bond strength after pressing ceramic plasticity was measured with a universal testing machine. For a test of the significance, a one-way ANOVA was performed, and Tukey's multiple comparison test was conducted. Results: The observation of the surface roughness was SB04($2.22{\pm}1.16{\mu}m$), SB08($2.98{\pm}0.33{\mu}m$), SB12($2.44{\pm}1.32{\mu}m$), SB20($2.34{\pm}0.59{\mu}m$) and SA04($2.34{\pm}0.67{\mu}m$), SA08($1.28{\pm}0.90{\mu}m$), SA12($2.03{\pm}1.60{\mu}m$), SA20($2.19{\pm}1.73{\mu}m$). In the case of ZN Group, the shear bond strength was ZN04($23.26{\pm}3.83MPa$), ZN08($21.76{\pm}2.33MPa$), ZN12($20.49{\pm}3.01MPa$), ZN20($24.98{\pm}4.22MPa$)(p<0.05). As for ZL Group, the shear bond strength was ZL04($25.09{\pm}5.67MPa$), ZL08($22.98{\pm}2.26MPa$), ZL12($21.54{\pm}5.70MPa$), ZL20($23.98{\pm}3.23MPa$)(p<0.05). Conclusion: The research results showed that the bond strength of Zirconia core and Pressing ceramic was further improved by physical surface treatment before sintering, rather than by chemical bonding through liner surface treatment.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.16-16
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• 2014

본 논문에서는 polymer 기판 위에 direct inkjet patterning을 효율적으로 수행하기 위하여 기판 표면의 chemical bonding과 morphology를 in-line system 적용이 가능한 near atmospheric pressure plasma (N-APP)를 이용 하여 기판을 modifying 시켰다. modified substrate 위에 inkjet printing을 이용하여 metal interconnection을 하였다. 그 결과 기존 기판에서의 line width 보다 얇은 선폭을 획득 하였고 adhesion이 향상 되었다.