• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.148-154
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• 2016

A study on the micro particle blasting was conducted to find the optimum conditions of the blasted surface of aluminum 6061. The particle type such as $Al_2O_3$ and SiC, nozzle diameter, pressure, standoff distance and injection time were used as blasting conditions. Statistical method of orthogonal arrays(ANOVA) was used to find optimum conditions of maximum depth and maximum diameter of blasted surface. Particle type, nozzle diameter, and pressure were found to be the main factors of maximum blasted depth and diameter. Maximum blasted diameter was affected by increasing pressure and nozzle diameter but saturated maximum diameter. Maximum blasted depth was affected by pressure and nozzle diameter when aluminum 6061 was blasted with $Al_2O_3$ particle. The value of surface roughness was increased as pressure and nozzle diameter increased when aluminum 6061 was blasted with SiC.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.3
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• pp.620-631
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• 1996

Bonding of resin to cast alloy has traditionally been provided by mechanical retention. But, chemical bonding methods such as silicoating, tin plating, heat treatment, application of 4-META adhesives, have been developed to overcome the problems of the mechanical bonding methods. Silicoating has been used availaby in fixed prosthodontics, but is also reported to be used in removable prosthodontics. The aim of this study is to measure the tensile bond strength between resin and metal, and compare the effect of the type of metal and the grain size of the aluminum oxide on the bond strength, after metal surface roughening, coating of the opaque resin, and curing of heat-curing resin were performed. The test groups were divided into 4 groups according to the cast alloys and the aluminum oxide particles used. Group 1 : Type 4 gold alloy(DM66) blasted with $$50{\mu}m\;Al_{2}O_3$$ Group 2 : Type 4 gold alloy(DM66) blasted with $$250{\mu}m\;Al_{2}O_3$$, Group 3 : Co-Cr alloy(Nobilium) blasted with $$50{\mu}m\;Al_{2}O_3$$ Group 4 : Co-Cr alloy(Nobilium) blasted with $$250{\mu}m\;Al_{2}O_3$$ * 10 test specimens were made on each group. The specimens were thermocycled, and Instron Universal testing machine was used to measure the tensile bond strength of the finished specimens. The results were as follows : 1. Bond strengths showed that the group of gold alloy blasted with $250{\mu}m$ aluminum oxide particle had higher bond strength, and the group of gold alloy blasted with $50{\mu}m$ aluminum oxide particles had lower bond strength than any of the other groups. 2. Gold alloy had significantly higher bond strength when blasted with $250{\mu}m$ aluminum oxide particles than $50{\mu}m$, but. Co-Cr alloy showed no statistically significant difference between the two particle sizes. 3. When blasted with $50{mu}m$ aluminum oxide particles, Co-Cr alloy showed significantly higher bond strength than gold alloy. And, when blasted with $250{\mu}m$ aluminum oxide particles, gold alloy had significantly higher bond strength than Co-Cr alloy. 4. On the examination of the fractured sites, only the group of Co-Cr alloy blasted with $50{\mu}m$ aluminum oxide particles showed a part of residual opaque resin, but all the samples of the other groups fractured between the resin and the metal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.505-511
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• 1993

The results were obtained with changes according to the surface roughness of work roll and method to make the peak count on the roll in the temper rolling, and factors to affect to the work roll surface in actual rolling machine(ie. Temper mill). Conclusions are as follows. 1. E.D.T(Electro-discharge texturing)roll is more uniform roughness distribution than shot blasted roll and it's life time is two timees longer than that of shot blasted because it has more sine wave roughness. 2. The higher peak count of surface roughness, the more time is necessary to work roll texturing In shot blasting method, Surface roughness is relating to the grit size,impeller speed and hardness of roll material, But is can't control the peak count. 3. In shot blast texturing, Surface roughness of temper rolled strip which is transfered surface roughness of work roll is more ununiform than that of E.D.T roll 4. E.D.T roll has more uniform than the shot blasted roll and has more peak count than that of shot blasted roll. The surface of painted strip to image clarity is superior to that of shot blasted roll because E.D.T roll has more peak count and smooth surface.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.961-965
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• 2000

This study aims to predict the particle size of blasted rock. For this purpose, Predicted particle sizes were compared with the measured particle sizes at the rock blasting sites, where various blasting patterns which controls the bench height, depth of blasted hole, burden, spacing etc were tested. the difference of mean fragment size between measured and predicted values was 0.11m.

• Journal of Periodontal and Implant Science
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• v.33 no.4
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• pp.717-728
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• 2003

This study was performed to evaluate the difference of the bone-to-implant contact according to the surface roughness of the implants. Two beagles were used in the experiment. Extraction of the all premolars was performed in the mandible. In 3 months of healing, screw-shaped pure titanium machined surface implants (Implantium(R), Dentium Co. Korea), implants blasted with 45${\mu}m$ $TiO_2$ particles, (Implantium(R), Dentium Co. Korea) and implants blasted with 100${\mu}m$ $TiO_2$ particles (Implantium(R), Dentium Co. Korea) in diameter 3.4mm and length 6mm were installed in the edentulous mandible. Each dog was sacrificed at 4, 12 weeks after placement and then nondecalcified specimens were prepared for histologic analysis. The results of this study were as follows. 1. At 4 , 12 weeks after the surgery, bone-to-implant contact in the surface blasted with $TiO_2$ particles was higher than that in the pure titanium machined surface respectively. 2. Osseointegration in the surface blasted with 45${\mu}m$ $TiO_2$ particles was more increased than that in the surface blasted with 100${\mu}m$ $TiO_2$ particles. 3. Bone-to-implant contact was increased with time independent of surface roughness. 4. Bone formation was in the outfolded area more than inside the threads independent of surface roughness. From the above results, we were able t o find the most bone-to-implant contact in 45${\mu}m$ $TiO_2$ blasted implant.

• Journal of Periodontal and Implant Science
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• v.34 no.4
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• pp.699-709
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• 2004

The present study was performed to evaluate histomorphological difference in various surface-treated implants in beagle. Implants($Implantium^{(R)}$, Dentium Co. Korea) with pure titanium machined surface, acid treated surface, and $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acid treated surface were used in this study. All mandibular premolars of $1.5{\sim}2$ year old male beagle dogs were extracted. At 3 months after extraction, the implants(${\Phi}$ 4mm, l 6mm) were installed. The beagle were sacrificed at 1, 3 months after installation and then tissues including implants were prepared for non-decalcified specimens. These specimens were analyzed comparatively under light microscope. The results of this study were as follow 1. Higher rate of osseointegration were showed in the $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acid-treated surface. 2. Increased osseointegration were showed in the $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acidtreated surface with time. 3. Higher maturation of integration were showed in the $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acid-treated surface. In conclusion, surface treatment of $Al_2O_3blasted$ with acid might be considered to shorten healing time and improve success rate as increasing contact of implant and bone.

• 대한치주과학회:학술대회논문집
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• 2005.11a
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• pp.65-65
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• 2005

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.1
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• pp.3-9
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• 2001

The investigation of the fragmentation of blasted rocks is particularly important because it is a measure of the blast efficiency. The degree of fragmentation has a major effect on the efficiency of the loading and crushing operations. Getting such an information on the large pile of blasted rock is not an easy operation. This paper presents the results of case study to evaluate the performance of two types of tunnel blasting: V-cut and burn cut. The digital images of muckpiles were analyzed to produce size distribution and it was compared with those of predictive equations.

• Explosives and Blasting
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• v.37 no.4
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• pp.26-35
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• 2019

In designing a gravity-type anchorage of earth-anchored suspension bridge, the contact friction between a blasted rock mass and the concrete anchorage plays a key role in the stability of the entire anchorage. Therefore, it is vital to understand the shear behavior of the interface between the blasted rock mass and concrete. In this study, a portable 3D LiDAR scanner was utilized to scan the blasted bottom surfaces, and rock surface roughness was quantitatively analyzed from the scanned profiles to apply to 3D FEM modelling. In addition, based on the 3D FEM model, a three-dimensional dynamic fracture process analysis (DFPA-3D) technique was applied to study on the shear behavior of the interface between blasted rock and concrete through direct shear tests, which was analyzed under constant normal load (CNL). The effects of normal stress and the joint roughness on shear failure behavior are also analyzed.

• Corrosion Science and Technology
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• v.6 no.5
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• pp.219-226
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• 2007

Pre-construction primer (PCP), or shopprimer, have been applied to steel plates to control temporary corrosion during ship fabrication. For surface preparation at ship block stage, in common shipyard practices, welding beads, burnt and rusted areas shall be blasted or power tool cleaned and the contamination such as zinc salt shall be removed with blasting or power tool. Whereas, the sound film of PCP needs not to be removed or roughened as the paint having good compatibility with PCP is used for the first coat. In many cases, however, full blasting or sweep blasting on the sound PCP treated block assemblies was requested. There still has been argument about the legitimacy of this practice, thus, it is critical to evaluate the quality of the coating system applied on the sound PCP retained condition, comparing with the one applied on the full blasted or sweep blasted condition. In this study, two different epoxy systems for water ballast tank were applied on the surfaces with sound PCP condition, full blasted condition, and sweep blasted condition. Coating performances such as durability, anti-corrosion, cathodic disbondment resistance were evaluated. The test results clearly indicated that the sound film of PCP needed not to be removed or roughened as the paint having good compatibility with PCP based on inorganic zinc silicate.