• The Journal of Korean Academy of Prosthodontics
• /
• v.32 no.3
• /
• pp.378-395
• /
• 1994

The purpose of this study was to investigate the effect of various metal surface treatments and adhesive systems on the flexural bond strength of composite resin to Au-Ag-Cu-Pd alloy. The specimens were divided into nine groups by the combinations of surface treatment methods and adhesive systems. The types of surface treatment in this study were alumina blasting only, alumina blasting-Sn plating, alumina blasting-heating and three kinds of adhesive system used in this study were Silicoater system(Heraeus Kulzer GmbH,Germany), Superbond C & B(Sun Medical Co.,Ltd.,Japan) and Cesead opaque primer(Kurary Co.,Ltd.,Japan). After surface treatments and adhesive systems were applied, each specimen was built up with Dentacolor composite resin (Heraeus Kulzer GmbH,Germany). Four-point flexural bond strength was measured by Instron universal testing machine (Model 4301,U.S.A.) and modes of failure were observed by SEM(JEOL,SSM-840A,Japan). The obtained results were as follows: 1. The group that was bonded with Superbond C & B after alumina blasting-heating shelved the highest bond strength with significant difference among the groups, except the group with Cesead opaque primer after alumina blasting-Sn plating(P<0.05). 2. In the groups bonded with Cesead opaque primer, there was significant difference only in the bond strength between the alumina blasting-Sn plating group and alumina blasting group, where the former showed a higher bond strength(P<0.05). 3. In the groups bonded with Silicoater system, there were no significant differences in bond strength regardless of the surface treatment method(P<0.05). 4. In SEM evaluation, the groups of high bond strength, especially bonded with Superbond C & B after alumina blasting-heating and Cesead opaque primer after alumina blasting-Sn plating, revealed mainly cohesive-adhesive failure, whereas the others showed the tendency of adhesive failure.

• The Journal of Korean Academy of Prosthodontics
• /
• v.38 no.2
• /
• pp.160-168
• /
• 2000

This study evaluated the effects of four adhesive metal primers on the shear bond strength of a heat curing denture base resin(Lucitone 199) to cobalt-chromium alloy(Biosil-f). The adhesive metal primers were Cesead Opaque Primer, Metal Primer, MR Bond, and Super-Bond liquid. The metal surface primed or nonprimed was filled with the heat-curing methyl methacrylate resin. The specimens were stored in water at $37^{\circ}C$ for 24 hours and the alternately immersed in water bath at $5^{\circ}C\;and\;55^{\circ}C$ for up to 2,000 thermal cycles. Shear bond strengths were measured using UTM at a crosshead speed of 0.5mm/min. Failure surface were examined under magnifying glasses. All the primers examined improved the shear bond strength between denture base resin and cobalt-chromium alloy compared with nonprimed specimens before thermal cycling. The bond strength of Cesead Opaque Primer was greatest. And after 2,000 thermal cycles, the bond strengths between resin and cobalt-chromium alloy were decreased but the difference between thermal cycling 0 and 2,000 at Cesead Opaque primer and Metal Primer were not significant. This study indicated that Cesead Opaque Primer & Metal Primer is effective primers to obtain higher bond strength between heat cured denture base resin and cobalt-chromium alloy.

• The Journal of Korean Academy of Prosthodontics
• /
• v.29 no.2
• /
• pp.195-209
• /
• 1991

When the porcelain fused to metal restorations were fractured at the metal interface, various techniques and materials for intraoral porcelain repair have been suggested. The purpose of this study was to investigate the effect of metal surface treatment method and water storage on the shear bond strength of four porcelain repair systems. : Clearfil(Kuraray), All-bond(Bisco), Superbond C & B(Sun Medical), Panavia OP(Kuraray). After the metal surfaces of the specimens were sandblasted by aluminum oxide or roughened by diamond point, they were stored in double deionized water(24 Hr., $37^{\circ}C$) and thermocycling was performed(24 Hr., 1024 cycles), and again half of specimes were stored in water bath(2 Months, $37^{\circ}C$). Mean shear bond strength and mode of failure were recorded. The results of this study were obtained as follows : 1. Differences were observed between the sandblasted and diamond - treated specimens in Clearfil, All-bond, and Superbond. No statistically significant differences were observed in Panavia. 2. The 2-month storage time significantly affected the bond strength of All-bond and Superbond. No statistically significant differences were observed in Clearfil and Panavia. 3. The failures were observed at the interface between opaque resin and the metal in Clearfil and All-bond. 4. The failures were observed at the interface between opaque resin and veneered resin in Panavia. The failures were observed at the interface between opaque resin and veneered resin in Superbond, but 40% of them were fractured at the interface between the metal and opaque resin after 2-month storage time.

• Korean Journal of Cognitive Science
• /
• v.27 no.3
• /
• pp.421-439
• /
• 2016

The present study investigates the effects of semantic transparency on the learning of new words using both behavioral measures and event-related brain potentials. Participants studied novel words with either semantically transparent or opaque definitions while their brain potentials were recorded. Learning performance was assessed with both a lexical decision task and a recall test. The results indicated that transparent novel words were easier to learn than opaque words. More specifically, self-paced learning times were shorter for transparent novel words across three study sessions. Transparent words also elicited reduced N400s compared with opaque words in all sessions. Moreover, lexical decisions to both learned novel words and real words were faster and more accurate within the transparent condition compared to the opaque condition. These results suggest that semantic transparency also plays an important role within word learning, just as within word recognition, further supporting the notion that morphological information is critical within lexical processing.

• Journal of the Korea Society of Computer and Information
• /
• v.29 no.3
• /
• pp.91-98
• /
• 2024

In this paper, we present a particle-grid blending framework based on a geometric approach to efficiently represent opaque ice spheres with air bubbles. The water temperature is diffused through the grid and the air bubbles represented inside the ice through the particles. To solve the problem of previous methods that generate noisy dissolved air fields, we use levelsets to lighten the algorithm, i.e., the number of active particles and the initial amount of dissolved oxygen can be used to efficiently control the termination conditions of heat diffusion. We also extend the previous dissolved air field method, which only computes near air bubbles, to transparent regions to represent realistic ice spheres, and introduce a levelset-based approach to accurately compute the orientation of particles. As a result, the method presented in this paper is about three times faster than the existing methods and shows visually improved visualization of opaque ice spheres, which can be used in the field of representing physical virtual ice forms.

• The Journal of Korean Academy of Prosthodontics
• /
• v.25 no.1
• /
• pp.41-54
• /
• 1987

The purposes of this study were to evaluate the color differences those can exist between different brands of porcelain with identical shade designation, and to find their causes. For these purposes the following experiments were executed: The color of each opaque and layered porcelain specimen was determined by spectral reflectance measurements with a spectrophotometer. The compositions of each opaque porcelain powder were analyzed by qualitative, and quantitative analysis. Microscopic structures of each opaque porcelain were observed by scanning electron microscope. The results were as follows: 1. Identical shade of different brands of porcelain produced significantly different colors. 2. Color differences among the three brands were found under different light sources. 3. Color differences among the three brands were mostly a result of differences in kinds and amounts of opacifying agents and fluxes and microstructure of porcelain systems. 4. When porcelain systems have similar compositions and firing cycles, they produced similar colors.

• The Journal of Korean Academy of Prosthodontics
• /
• v.20 no.1
• /
• pp.33-49
• /
• 1982

This study was undertaken to observe the porcelain porosity exerted by the contamination of the alloy and liquid. The alloy used in this study was Jelstar; liquids were Ceramco Sta-Wet liquid, distilled water and tap water; and Ceramco vacuum porcelain powder was used. The measurements with photomicroscope (x200, Olympus) were made on the porosity, the diameter (mm) of the pores and the numbers of the pores ($No/mm^2$) The results of this study were obtained as follows: 1. In the porosity, the opaque layer contained over 70% of the total porosity, and the porosity was increased about twice in every porcelain layer by the tap water. 2. The contamination of the alloy and liquid caused porosity to increase markedly at the interface of the metal-porcelain. 3. The diameter of the pores were increased about 1.5 times larger by the contaimination of the liquid, and only a slight increase in the opaque layer due to the contamination of the alloy. 4. In the numbers of the pores, there were significant differences according to the contamination of the alloy and the porcelain layer. And the contamination of the liquid caused significant differences only in the opaque layer.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.10
• /
• pp.93-99
• /
• 2010

A nano-stereolithography is the direct patterning process with a nanoscale resolution using twophoton absorption induced by a femtosecond laser. However, in the majority of the works, the fabrication of 3D microstructures have been done only onto transparent glass due to the use of an oil immersion objective lens for achieving a high resolution. In this work, the coaxial illumination and the auto-focusing system are proposed for the direct patterning of nano-precision patterns on an opaque substrate such as a silicon wafer and a metal substrate. Through this work, 3D polymer structures and metallic patterns are fabricated on a silicon wafer using the developed process.

• Journal of the Korean Society of Visualization
• /
• v.4 no.2
• /
• pp.69-75
• /
• 2006

The microbubbles were used in various fields, such as turbulent control, drag reduction, material science and life science. The X-ray PTV using X-ray micro-imaging technique was employed to mea-sure the size and velocity of micro-bubbles moving in an opaque tube simultaneously. Micro-bubbles of $10{\sim}60{\mu}m$ diameter moving upward in an opaque tube (${\phi}$=2.7mm) were tested. Due to the different refractive indices of water and air, phase contrast X-ray images clearly show the exact size and shape of over-lapped microbubbles. In all of the working fluids tested (deionized water, tap water, 0.01 and 0.10M NaCl solutions), the measured terminal velocity of the microbubbles rising through the solution was proportional to the square of the bubble diameter. The rising velocity was increased with increasing mole concentration. The microbubble can be useful as contrast agent or tracer in life science and biology. The X-ray PTV technique should be able to extract useful information on the behavior of various bio/microscale fluid flows that are not amenable to analysis using conventional methods.

• Journal of Technologic Dentistry
• /
• v.39 no.3
• /
• pp.153-159
• /
• 2017

Purpose: In this study, a corresponding porcelain coating material was applied to dental Co-Cr metal among PFM. Methods: The bonding strength of the fired specimens was measured by a three-point flexural rigidity test. SEM/EDS was used to observe the surface component of specimens. Results: First, All groups were higher than the minimum bonding strength of 25 MPa specified in ISO 9693 for dental metal-ceramics specimens. Second, The bonding strength of control group(WO) is 44.64 MPa. Experimental group DM was 35.45 MPa and DP was 31.82 MPa(P<0.05). Tukey's HSD tests results have shown that the bonding strength in control group(WO) is higher than that of experimental group(DM, DP). Third, In the case of metal - porcelain bonding strength, the application of opaque porcelain and firing were higher than those of the group treated with degassing process. Conclusion: The bonding strength was higher when the powder opaque porcelain was applied than the paste opaque porcelain.