• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1989.06a
• /
• pp.63-65
• /
• 1989

Piezoelectric BaTiO$_3$-polymer composite were investigated for dielectric and piezoelectric properties with the barium titanate active particle size. Under the condition of the same density and ceramic volume ratio of composite, the dielectric and piezoelectric constant of composite are increasing as the ceramic particle size in composite are increasing. The surface layer model was quoted to explain these phenomena in our system and experimentally confirmed. The connectivity parameter of modified cube model of composite was calculated from the dielectric constant variation as their particle size. The connectivity parameter X and Y were 77.8% and 98.9% respectively. It means that the barium titanate particle distribution in composite nearly approach to the parallel mode. It was experimentally confirmed that the surface layer has low dielectric and nonferroelectric properties. Dielectric constant and thickness of surface layer were calculated from the equivalent circuit of composite.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2008.11a
• /
• pp.6-7
• /
• 2008

Composite nanoparticles of silica-polyaniline were synthesized and tested as an electrochromic material. For the optical application, the size of the nanoparticle was intended to be less than 100 nm in diameter. The synthesis was done by using a microemulsion synthesis method where the silica-polyaniline composite nanoparticle was obtained by dispersing two acidic aqueous phases containing aniline and polymerization agent, respectively. Microstructure analysis such as TEM and BET surface area measurement showed the possibility that polyaniline is incorporated in porous silica structure. The composite structure of the particle was proved to enhance chemical stability of the prepared electrochromic film.

• Proceedings of the KACD Conference
• /
• 2003.11a
• /
• pp.572-572
• /
• 2003

There were attempts to reduce the micro leakage and surface roughness of resin composite. One of them is surface sealing. The purpose of this study was to compare the effect of materials, specifically developed for surface sealing, on microleakage and surface roughness in Class V composite restorations. Twenty five standardized Class V cavity preparations were made on the facial surface of extracted human premolars and were randomly assigned to 5 groups. The teeth were restored with Z-250 resin composite after applying Single Bond adhesive system.(중략)

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.12
• /
• pp.130-138
• /
• 1995

Machined graphite/epoxy surfaces were studied by using SEM (Scanning Electron Microscopy), surface profilometry and its analysis to determine suitable surface describing parameters for machined unidirectional and multidirectional laminate composite. The surface roughness and profile are found to be highly depdndent on the fiber layup direction and the measurement direction. It was possible to machine 90 .deg. and -45 .deg. plies due to the adjacent plies, which were holding those plies. It was found that the microgeometrical variations in terms of roughness parameters $R_{a}$ without $D_{y}$(Maximum Damage Depth) region and $D_{y}$are better descriptors of the machined laminate composite surface than commonly used roughness parameters $R_{a}$and $R_{max}$ The characteristics of surface profiles in laminate composite are well represented in CPD (Cumulative Probability Distribution) plot and PPD (Percentage Probability Density) plot. Edge-trimmed multidirectional laminate surfaces are Gaussian and random for profiles measured along the tool movement direction, they are periodic and non-Gaussian in the direction perpendicular to the tool movement.t.ent.t.

• Journal of the Korea Concrete Institute
• /
• v.13 no.3
• /
• pp.206-212
• /
• 2001

The purpose of this experimental study was to investigate the material properties of concrete surface preparator with inorganic composite, which was modified with plaster and admixture. A series of experiment were conducted to appraise the properties according to KS F 4716. The experimental results were as follows ; When the concrete surface preparator with inorganic composite was used, the hair crack and split, due to early drying shrinkage, was little. So it is superior to concrete surface preparator with cement paste plaster The bonding strength of concrete surface preparator with inorganic composite increased about 60% compared to that of concrete surface preparator with cement paste plaster. The workability of surface flatness and finishing was superior compared to that of existing concrete surface preparator. All specifications on concrete surface preparator were satisfied in the series of this experiments. Therefore, the concrete surface preparator with inorganic composite might be satisfactory applied in field due to its superior material properties.

• The Journal of Advanced Prosthodontics
• /
• v.6 no.3
• /
• pp.194-199
• /
• 2014

PURPOSE. This study evaluated the depth of cure of resin composite cured by light through a translucent fiber post. MATERIALS AND METHODS. The opaque plastic tubes in various lengths of 2, 4, 6, 8, 10, 12, 14 mm. were filled with resin composite in which two different translucent fiber posts were inserted into the center and photo-polymerized for 40 seconds. The degree of conversion of the cured composite at bottom surface were examined using Fourier transform infrared attenuated total reflection spectrometer (FTIR/ATR) at 0.1, 0.5 and 1.0 mm apart from the post surface. RESULTS. The degree of conversion of the 0.1 mm, 0.5 mm, 1.0 mm apart from the post surface was highest at the 2 mm level and continuously decreased when the distance from the light source was increased and drastically decreased when the depth from the top of the post was greater than 4-6 mm. For each level, the highest degree of conversion was at 0.1 mm from the post surface and decreased continuously when the distance apart from the post surface was increased. CONCLUSION. The quantity of light transmission depends on the type of post and the light transmission capability of the post, especially after 4-6 mm depth and the area further apart from the post surface, are insufficient for clinical light activation of resin composite.

• Journal of the Korean institute of surface engineering
• /
• v.22 no.1
• /
• pp.43-51
• /
• 1989

The characteristion of composite electroless Nikel palting on the condition of adding 3kinds ceramic dispersives, Al2O3, Si3O4 and artificial diamond powder were studied. Decreasing solution temperature for composite plating was required to depress the spontaneous decomposition caused by dispersive including enlargement of reaction surface. The rate of composite plating was faster than that of general electroless-Nickel plating without dispersive. this increasing tendency of plating rate was remarkable for the active catalysis, like diamond powder.

• Restorative Dentistry and Endodontics
• /
• v.45 no.1
• /
• pp.12.1-12.8
• /
• 2020

Objectives: The aim of this in vitro study was to evaluate the microhardness and surface roughness of composite resins before and after tooth bleaching procedures. Materials and Methods: Sixty specimens were prepared of each composite resin (Filtek Supreme XT and Opallis), and BisCover LV surface sealant was applied to half of the specimens. Thirty enamel samples were obtained from the buccal and lingual surfaces of human molars for use as the control group. The surface roughness and microhardness were measured before and after bleaching procedures with 35% hydrogen peroxide or 16% carbamide (n = 10). Data were analyzed using 1-way analysis of variance and the Fisher test (α = 0.05). Results: Neither hydrogen peroxide nor carbamide peroxide treatment significantly altered the hardness of the composite resins, regardless of surface sealant application; however, both treatments significantly decreased the hardness of the tooth samples (p < 0.05). The bleaching did not cause any change in surface roughness, with the exception of the unsealed Opallis composite resin and dental enamel, both of which displayed an increase in surface roughness after bleaching with carbamide peroxide (p < 0.05). Conclusions: The microhardness and surface roughness of enamel and Opallis composite resin were influenced by bleaching procedures.

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1061-1065
• /
• 1995

To improve dielectric and mechanical properties of insulating composite by plasma surface treatment, new plasma surface treatment process is designed with concentric and hemi-circle electrodes system, the plasma, which is generated between anode and cathode, is induced to the upper side of the electrode system and treats the surface of the insulators. The optimal surface treatment condition is that pressure : 0.5[torr], flux density 100[gauss], discharge current : 500[mA] and treatment time : 3 minutes. The composite filled with glass cloth surface-treated by plasma shows the improvement in electric and mechanical properties, comparing non- and coupling agent-treated samples.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.11a
• /
• pp.75-78
• /
• 2000

This study investigates the effect of surface treatment on the shear strength between aluminum panel and composite plate. The aluminum panel was surface-treated by DC Plasma and the composite Plate was surface-treated by ion beam. Lap shear test and T-peel test were performed to determine the shear strength and T-peel strength. Results showed that the shear strength of surface-treated case was 2.5 times higher than that of untreated case. The T-peel strength of treated case was more than 5 times higher than that of untreated case. SEM examination showed that the strength increase of surface-treated case was due to the more spread of epoxy to the panel.