• Journal of Periodontal and Implant Science
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• v.35 no.4
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• pp.839-850
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• 2005

The success of an implant is determined by its integration into the tissue surrounding the biomaterial. Surface roughness is considered to influence the behavior of adherent cells. The aim of this in vitro study was to determine the effect of surface roughness on Saos-2 osteoblast-like cells. Titanium disks blasted with 75 ${/mu}m$ aluminum oxide particles and machined titanium disks were prepared. Saos-2 were plated on the disks at a density of 50,000 cells per well in 48-well dishes. After 1 hour, 1 day, 6 days cell numbers were counted. One day, 6 days after plating, alkaline phosphatase(ALPase) activity was determined. Compared to experimental group, the number of cells was significantly higher on control group. The stimulatory effect of surface roughness on ALPase was more pronounced on the experimental group than on control group. These results demonstrate that surface roughness alters proliferation and differentiation of osteoblasts. The results also suggest that implant surface roughness may play a role in determining phenotypic expression of cells.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.264-270
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• 2002

This paper presents roughness effects on flow characteristics and efficiency of multi-stage axial compressor using numerical simulation. which is carried out with a commercially available software, CFX-TASCflow. In this paper, the third of four stages of GE low pressure compressor is considered including me stator and rue rotor. Mixing-plane approach is adopted to model the interface between the stator and the rotor: it is appropriate for steady state simulation. First, a flat plate simulation was performed to validate how exact the numerical simulation predicts the roughness effect for smooth and rough walls. Then GE compressor model was calculated about at each roughness height. Concluding, very small roughness height largely affects the performance of compressor and the increasing rate of loss decrease as roughness height increase.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.52-59
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• 2004

Recently the high speed end-milling processing is demanded the high-precise technique with good surface roughness and rapid time in aircraft, automobile part and molding industry. The working factors of high speed end-milling has an effect on surface roughness of cutting surface. Therefore this study was carried out to analyze the working factors to get the optimum surface roughness by design of experiment. From this study, surface roughness have an much effect according to priority on distance of cut, feed rate, revolution of spindle and depth of cut. By design of experiment, it is effectively represented shape characteristics of surface roughness in high speed end-milling. And determination($R^2$) coefficient of regression equation had a satisfactory reliability of 76.3% and regression equation of surface roughness is made by regression analysis.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.26-31
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• 1998

The effect of tool angles on the surface roughness in face milling is studied. First, the relation between tool angles and rotation angles is identified. Using this relationship, it is obtained that the projection of insert nose shape on cutting profile, which is a part of ellipse. The effect of spindle tilt is also considered for the tool angles. It si shown that tool angles along with nose radius and feed rate have an effect on surface roughness.

• Journal of the Korean Society for Heat Treatment
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• v.22 no.6
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• pp.368-374
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• 2009

Nickel titanium shape memory alloys (NiTi) have been investigated for applications in the biomedical industry. However, little is known about the influences of surface modifications on the propertise of these alloys. The effect of electropolishing and heat treatments was found to exhibit significant surface roughness. Change of phase was B2, r-phase and B19' by heat treatments. In this study, effect of the electropolishing conditions on surface roughness is investigated in Ni-Ti alloys (Nitinol). Variation in phases with heat treatment temperature is investigated for a Ni-Ti alloy by X-ray diffraction and DSC. Characteristic of the microstructure have been observed by SEM. Surface roughness have been measured by AFM. The results clearly show that significant different in surface property to heat treated at $500^{\circ}C$ (R-phase). $TiO_2$ phases preciritated all of the specimens. It is not good effect of surface roughness because made to surface relief. The surface roughness appears to be important in the property of Ni-Ti alloys for biomedical applications.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.3
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• pp.261-270
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• 2006

The success of an implant is determined by its integration into the tissue surrounding the biomaterial. Surface roughness is considered to influence the behavior of adherent cells. The aim of this in vitro study was to determine the effect of surface roughness on Saos-2 osteoblast-like cells. Titanium disks, blasted with $75{\mu}m$ aluminum oxide particles and anodic oxidized and machined titanium disks were prepared. Saos-2 were plated on the disks at a density of 50,000 cells per well in 48-well dishes. After 1 hour, 1 day, 6 days cell numbers were counted. One day, 6 days after plating, alkaline phosphatase(ALPase) activity was determined. Compared to experimental groups, the number of cells was significantly higher on control group. The stimulatory effect of surface roughness on ALPase was more pronounced on the experimental groups than on control group. These results demonstrate that surface roughness alters proliferation and differentiation of osteoblasts. The results also suggest that implant surface roughness may play a role in determining phenotypic expression of cells.

• Journal of Mechanical Science and Technology
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• v.20 no.8
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• pp.1266-1274
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• 2006

A numerical study is performed to investigate the effect of inner surface roughness and micro-particles on adiabatic single phase frictional pressure drop in a perfect square micro channel. With the variation of particles sizes (0.1 to $1{\mu}m$) and occupied volume ratio (0.01 to 10%) by particles, the Eulerian multi-phase model is applied to a $100{\mu}m$ hydraulic diameter perfect square micro channel in laminar flow region. Frictional pressure loss is affected significantly by particle size than occupied volume ratio by particles. The particle properties like density and coefficient of restitution are investigated with various particle materials and the density of particle is found as an influential factor. Roughness effect on pressure drop in the micro channel is investigated with the consideration of roughness height, pitch, and distribution. Additionally, the combination effect by particles and surface roughness are simulated. The pressure loss in microchannel with 2.5% relative roughness surface can be increased more than 20% by the addition of $0.5{\mu}m$ diameter particles.

• Tribology and Lubricants
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• v.21 no.1
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• pp.1-7
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• 2005

Effect of Surface roughness on nanoscale adhesion was studied experimentally by using colloidal probe technique. Glass micro balls having the radius of $3.3\~17.4{\mu}m$ were glued at the end of AFM cantilevers to prepare colloidal probes. Adhesion force between the colloidal probe and Si-wafer was measured using pull-off force measuring method. Results showed that the measured adhesion forces are not the function of the radius of the glued balls because the ball surfaces are rough. It is also found that roughness parameters such as $R_a,\;R_q\;and\;R_{max}$ do not have important role on nanoscale adhesion. In order to find the effect of surface roughness on nanoscale adhesion, the bearing areas were extracted from the measured topography of glued balls. After normalizing the measured adhesion force with the bearing area, it was found that the normalized adhesion force kept constant as function of the radius of glued ball.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.40-44
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• 2008

The interfacial adhesion energy between resist and a substrate is very important due to resist pull-off problems during separation of mold from a substrate in nanoimprint process. And effect of substrate surface roughness on interfacial adhesion energy is very important. In this paper, we have treated glass wafer surface using $CF_4$ gas for increase surface roughness and it has tested interfacial adhesion properties of UV resin/glass substrate interfaces by 4 point bending test. The interfacial adhesion energies by bare, 30, 60 and 90 sec surface treatments are 0.62, 1.4, 1.36 and 2 $J/m^2$, respectively. The test results showed quantitative comparisons of interfacial fracture energy (G) effect of glass wafer surface roughness.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1148-1153
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• 2004

Recently the high speed end-milling processing is demanded the high-precise technique with good surface rougj1ness and rapid time in aircraft, automobile part and molding industry. The working factors of high speed end-milling has an effect on surface roughness of cutting surface. Therefore this study was carried out to analyze the working factors to get the optimum surface roughness by design of experiment. From this study, surface roughness have an much effect according to priority on Spindle speed, feed rale, hardness and axial depth of cut By design of experiment, it is effectively represented shape characteristics of surface roughness in high speed end-milling And determination($R^2$) coefficient of regression equation had a satisfactory reliability of 89.7% and regression equation of surface roughness is made by regression analysis.