• Corrosion Science and Technology
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• v.17 no.2
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• pp.74-80
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• 2018

The electronic industries require environmentally-friendly and highly functional materials to enhance the quality of human life. Home appliances require insect repellent steels that work to protect household microwave ovens from incurring damage by insects such as fire ants and cockroaches in tropical regions. Thus, POSCO has developed new types of functional steels, coated with an array of organic-inorganic hybrid composites on the steel surface, to cover panels in microwave ovens and refrigerators. The composite solution uses a fine dispersion of hybrid solution with polymeric resin, inorganic and a pyrethroid additive in aqueous media. The hybrid composite solution coats the steel surface, by using a roll coater and is cured using an induction curing furnace on both the continuous galvanizing line and the electro-galvanizing line. The new steels were evaluated for quality performances, salt spray test for corrosion resistance and biological performance for both insect repellent and antimicrobial activity. The new steels with organic-inorganic composite coating exhibit extraordinarily biological functionalities, for both insect repellent and antimicrobial activities for short and long term tests. The composite-coating solution and experimental results are discussed and suggest that the molecular level dispersion of insecticide on the coating layer is key to biological functional performances.

• Composites Research
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• v.26 no.1
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• pp.54-59
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• 2013

This study deals with effect of plasma treatment on the properties of unidirectional ligno cellulosic fabric Hildegardia Populofolia (HDP) fabric. Thermal stability of the fabric was determined by differential scanning calorimetry (DSC) and Thermo gravimetric analysis (DSC). Morphological properties was analyzed by SEM analysis and found that the surface was rough upon plasma treatment which provides good interfacial adhesion with matrix during composite fabrication. Thermal stability and mechanical properties of the plasma treated fabric slightly increases compare to alkali and untreated fabric. It was observed that tensile properties of the fabric increases upon plasma treatment due to the formation of rough surface. SEM analysis indicates formation of rough surface on plasma treatment which helps in increasing the interfacial interaction between the matrix (hydrophobic) and fabric (hydrophilic).

• Journal of Technologic Dentistry
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• v.39 no.1
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• pp.9-16
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• 2017

Purpose: The purpose of this study was to evaluate flexural strength, composite surface and fractured surface of three different indirect composite resins. Methods: Fifteen bar-shaped specimens ($25mm{\times}2mm{\times}2mm$) were fabricated for each FL group (Flow type and Light curing) and PLP group (Putty type and Light, Pressure curing) and PL group (Putty type and Light curing) according to manufacturer's instructions and ISO 10477. Fabricated specimens were stored in the distilled water for 24 hours at the temperature of $37^{\circ}C$. Three-point bending strength test was performed to measure flexural strength using universal testing machine at a crosshead speed of 1mm/min (ISO 10477). Surface and fractured surface of specimens were observed by digital microscope. Results were analyzed with Kruskal-wallis tests (${\alpha}=0.05$). Results: Mean (SD) of three different indirect composite resins were 83.38 (6.67) MPa for FL group, 139.90(16.53) MPa for PLP group and 171.72(16.74) MPa for PL group. Flexural strength were statistically significant (p<0.05). Differences were not observed at fractured surface among three groups. However, many pores over $100{\mu}m$ were observed at PL group in observing surface of specimen. Conclusion: Flexural strength of composite resins was affected by second polymerization method and content of inorganic filler.

• Journal of dental hygiene science
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• v.21 no.4
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• pp.251-259
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• 2021

Background: The purpose of this study was to investigate the effects of commercially available calamansi soju and other alcoholic beverages on the microhardness and erosion of resin restorations. Methods: In this study, we evaluated the effects of Calamansi soju, Chamisul fresh, Cass fresh, and Gancia Moscato D'asti on resin restorations. Jeju Samdasoo and Coca-Cola were used as negative and positive controls, respectively. Specimens to be immersed in the beverages were manufactured using composite resin according to the product instructions. In each group, the surface microhardness was measured using a surface microhardness instrument before and after immersion for 5, 15, 30, and 60 minutes. The pattern of change in the surface of the composite resin was observed under a scanning electron microscope (SEM). Paired t-tests, one-way ANOVA, and repeated measures ANOVA were performed to compare the surface microhardness of the specimens, and the Tukey test was used as a post hoc test. Results: The pH of all beverages except Jeju Samdasoo was <5.5, which is the critical pH that can induce erosion. The difference in surface microhardness of the composite resin before and after immersion for 60 minutes was significant in all groups. In particular, the largest change in surface microhardness was observed in the calamansi soju group. In the SEM analysis, loss of composite resin was observed in all groups except the Jeju Samdasoo group, and rough surfaces with pores of various sizes were observed. Conclusion: In this study, all beverages except Jeju Samdasoo decreased the microhardness of the composite resin surface, and it was confirmed that calamansi soju had the greatest change.

• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.197-212
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• 1991

The purpose of this study was to roughness on the polished surface of visible light composite resins and was to observe the polished surfaces under Scanning Electrom Microscope(ISI DS 130 AKASHI Co. JAPAN). The surface roughness tester(Surfcom 700A Seimtsu profilometer Tokyo, Japan) was used to measure roughness of polished surfaces. In this study, 5 brands of visible of composite resins were examined, Pyrofile light bond Anterior Lite fil anterior Photo clearfil anterior & posterior Palfique light Anterior and posterior Silux Anterior. White point, Silicure point, Super snap Sof-Lex medium disk as cutting instrument, and celluloid matrix were used. The results obtained were as follows. 1. The Celluloid matrix produced the smoothest surfaces. 2. The surfaces made by Soflex medium disk was smoother than the surfaces made by any other polishing instruments. 3. The values of surface roughness made by White point, Silicon point and Super snap were similer. 4. Palfique light (AP) visible light composite resin showed the smoothest surface after polishing with Silicone point, Super snap disk and Soflex mediuem disk in all tested materials.

• International Journal of Safety
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• v.4 no.2
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• pp.6-11
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• 2005

The goals of the paper are to understand the impact damage behavior and identify the effect of surface protective materials on impact resistance in filament wound composite pressure vessels. For these, a series of low velocity impact tests was performed on specimens cutting from the full scale pressure vessel by the instrumented impact testing machine. The specimens are classified into two types, which are with and without surface protective material. The visualization for impact damage by two different impactors is made by metallurgical microscope. Based on the impact force history and damage, the impact resistance parameters were employed,rod its validity in identifying the damage resistance of filament wound composite pressure vessel was reviewed. As the results, the impact resistance of the filament wound composites and its dependency on the surface protective material were evaluated quantitatively

• Korean Membrane Journal
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• v.4 no.1
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• pp.12-19
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• 2002

Nanofiltration of aqueous dye solutions was carried out using polyamide (PA) nanofiltration (NF) composite membranes. The PA composite membranes were prepared by the interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) on the surface of microporous polysulfone (PSf) ultrafi1tration (UF) membranes. After characterization in terms of their permeation performance and surface ionic property, they were used for the separation of dye solutions such as Direct Red 75, 80, 81, and Direct Yellow 8 and 27. The separation conditions were varied to study the factors affecting on the permeation performance of the membranes: different concentrations of dye solutions, operating temperature and time, and flow rate of a feed solution. The surface property of the membrane, especially its ionic property, as a function of operating time was examined with a zeta-potentiometer and the relationship between the surface chemistry of the membrane and its permeation properties was also studied.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.4
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• pp.34-47
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• 2000

Since carbon fiber epoxy composite materials have excellent properties for structures due to their high specific strength, high specific modulus, high damping and low thermal expansion, the hollow shafts made of carbon fiber epoxy composites have been widely used for power transmission shafts for motor vehicles , spindles of machine tools, motor base, bearing mount for tool up and manufacturing. The molded composite machine elements are not usually accurate enough for mechanical machine elements, which require turning drilling , cutting and grinding. The experiment are surface grinding wheel GC60 to the carbon fiber epoxy composite specimen with respect to staking angle [0]nT , [45]nT, [90]nT on the CNC grinding machine. In this paper, the surface grinding characteristics of composite plate, which are surveyed experimentally and analytically with respect to the grinding force, surface roughness and wheel loading according to the variable depth of cut, wheel velocity and table feed rate are investigated.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.03a
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• pp.14-20
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• 2009

Atmospheric pressure air plasma was applied for treatment of different kinds of natural bamboo fiber to improve their mechanical properties and surface characteristics, which are suitable for adhesion and dyeing. The tensile strength and Young modulus of bamboo fiber were significantly improved; SEM and AFM study show that the surface of fiber became cleaner and rougher after plasma treatment. Plasma treatment caused the cracking, removing of the protective skin of alkali-untreated fiber and etching to form a cleaner and rougher surface. The dyeability of both groups of bamboo fiber which are used for composite and textile purposes is significantly enhanced after treatment.

• Carbon letters
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• v.10 no.2
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• pp.97-100
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• 2009

In this work, effects of carbon matrix on sliding friction and wear behavior of four kinds of C/C have been investigated against 40 Cr steel ring mate. Composite A with rough lamination carbon matrix (RL) shows the highest volume loss and coefficient of friction, while composite D with smooth lamination/resin carbon matrix (SL/RC) shows the lowest volume loss. The worn surface of composite A appears smooth, whereas that of composite C with smooth lamination carbon (SL) appears rough. The worn surface of composite D appears smooth under low load but rough under high load. Atomic force microscope images show that the size of wear particles on the worn surface is also dependent on the carbon matrix.