• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.2
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• pp.21-26
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• 2005

From on the machining center cutting work of 5534, the characteristics such as spindle speed and feed speed fir the third point height, average spacing of roughness peaks, bearing ratio, center line average, ten point height. experiments is roughness for sampling length determine to measuring length of cutting feed speed 200, 400, 600, 800mm/min and spindle speed 800, 1000, 1200, 1400rpm. Third point height is spindle speed with most suitable cutting condition 1000rpm. Third point height is feed speed with most suitable cutting condition 400mm/min. Average spacing of roughness peaks are spindle speed with most suitable cutting condition feed speed increased to average spacing of roughness Peaks are increased. Spindle speed increased to average spacing of roughness peaks are decreased. Bearing ratio is spindle speed with feed speed increased to bearing ratio decreased. Center line average is spindle speed with most suitable cutting condition at 1200rpm feed speed with most suitable cutting condition at 200mm/min to cutting foe roughness suddenly decreased. Ten point height is spindle speed with most suitable cutting condition 1200rpm at ten point height cutting face roughness to decreased and feed speed with most suitable cutting condition 800mm/min at ten point height cutting face roughness to decreased.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.2
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• pp.68-74
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• 2013

In this paper, an average surface roughness, $R_a$, was measured by optical measurement and its mathematical model according to spindle speed and feedrate was obtained by least square method. Also, its result is compared and investigated with real measured average surface roughness. The optical measurement of surface roughness is performed by CLSM(confocal laser scanning microscope) and the captured HEI(height encoded image) data is used as an original data for the generation of average surface roughness and its mathematical plane or contour surface of surface roughness. Using this polynomial model with two independent variables, the behavior of an average surface roughness is investigated and analyzed with an experimental modeling of least square algorithm. And it can be used for the prediction of $R_a$ in different condition of machining.

• Tribology and Lubricants
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• v.29 no.1
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• pp.27-32
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• 2013

This study examined the effects of surface roughness in the mixed lubrication regime of smooth and rough surfaces for roller bearings. The average flow model was adopted for interaction between the flow rheology of the lubricant and the surface roughness. The average Reynolds equation and related flow factor that describes the coupled effects of surface roughness and flow rheology, the viscosity-pressure and density-pressure equations, the elastic deformation equation, and the force balance equation were solved simultaneously. The results showed that the effects of surface roughness on the film thickness and pressure distribution should be considered, especially in elastohydrodynamic lubrication contact problems.

• Journal of Technologic Dentistry
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• v.37 no.4
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• pp.205-212
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• 2015

Purpose: The objective of this study was to compare the surface roughness according to polishing process in conventional laboratory techniques used for polishing three different acrylic denture base resins. Materials and methods: Specimen preparation and surface polishing procedures were conducted to manufacturer's recommendation with three heat-polymerized denture base resins. Surface roughness and gloss were measured by a contact type tester and a LED gloss checker using thickness 2 mm and diameter 10 mm. There were five specimens for each acrylic resin material and polishing procedures. Mean average surface roughness (Ra) values of each specimen group were analyzed using a one-way ANOVA analysis of variance and Scheffe's post hoc test. Surfaces after surface roughness and gloss testing according to each polishing process were evaluated under a stereoscopic microscope. Results: The highest mean average surface roughness was measured($Ra=2.43{\pm}0.47$) for surfaces finished with a denture tungsten carbide bur in Triplex. The lowest surface roughness values ($Ra=0.11{\pm}0.07$) were determined in Vertex polished with a lathe. In addition, all materials revealed that surface roughness determined highly in HP1 and HP2 than other procedures. All correlation between surface roughness and gloss showed highly with three heat-polymerized resins. Specially, topmost correlation revealed than other material in Triplex. Significant differences in mean average surface roughness were found between polishing process used high speed lathe and low speed hand-piece. Conclusion: Laboratory polishing used to high speed was found to produce the smoothest surface of heat-polymerized denture base acrylic resin. Therefore, we recommended that high polishing process need to get smooth surface.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.240-246
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• 2000

An in-process estimation of the ground surface roughness is a bottle-neck and an essential field in conventional grinding operation. We defined the dimensionless average roughness factor (D.A.R.F) that exhibits a roughness characteristics of ground surface. The D.A.R.F was composed easily of the absolute average and the standard deviation values which were the analytic parameters of the acoustic emission (AE) signal generated during the machining process. The theoretical equation between the surface roughness and the D.A.R.F has been derived from the linear regressive analysis and verified its availability through the experimentation on the surface grinding machine.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.2
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• pp.147-153
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• 1999

An in-process extraction method of the ground surface roughness is a bottle-neck and essential field in conventional machining process. We define the D.A.R.F(Dimensionless Average Roughness Factor) that has a roughness characteristic of ground surface. D.A.R.F include the absolute average and the standard deviation values which are the analytic parameters of the AE(Acoustic Emission) signal generated during the grinding operation. The theoretical equation between the surface roughness and the D.A.R.F has been derived from the linear regressive analysis and verified its availability through the experimentation on the surface grinding machine.

• Journal of Korean Society of Forest Science
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• v.112 no.3
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• pp.374-381
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• 2023

The travel time of flash floods along mountain streams is mainly governed by reach-average velocity, rather than by the point velocity of the locations of interest. Reach-average velocity is influenced by various factors such as stream geometry, streambed materials, and the hydraulic roughness of streams. In this study, the reach-average velocity in mountain streams was measured for storm periods using rhodamine dye tracing. The point cloud data obtained from a LiDAR survey was used to extract the average hydraulic roughness height, such as R_a, R_max, and R_z. The size distribution of the streambed materials (D₅₀, D₈₄) was also considered in the estimation of the roughness height. The field experiments revealed that the reach-average velocities had a significant relationship with flow discharges (v = 0.5499Q^0.6165 ), with an R² value of 0.77. The root mean square error in the roughness height of the R_a-based estimation (0.45) was lower than those of the other estimations (0.47-1.04). Among the parameters for roughness height estimation, the R_a -based roughness height was the most reliable and suitable for developing the reach-average velocity equation for estimating the travel time of flood waves in mountain streams.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.2
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• pp.23-30
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• 2008

As a basic machining process, turning is a widely used machining process in which a single-point cutting tool removes material from the surface of a rotating material. A common method of evaluating machining performance is to measure the surface roughness. In a turning operation, it is important to select cutting conditions for achieving high cutting performance. As a rule, cutting conditions can be classified into feed rate, depth of cut and insert radius. While cutting process even though cutting conditions are optimized, the average roughness can be deterioration due to wear of the cutting tool edge. In this study, the aim is to maintain the average roughness even though the cutting condition is irregularly changing within the predictable range due to the working environment. First, the surface roughness model influenced by cutting conditions is constructed based on the experimental results in a turning operation, Second, applying the sliding mode control theory to the turning operation model which is composed of the surface roughness model and the motor transfer function, the surface roughness is closed to the desired value. Finally, the effectiveness of this approach is demonstrated through the computer simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.9
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• pp.1491-1497
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• 1997

The purpose of this research is to improve the surface roughness of cast-iron pipe porduced by the centrifugal casting. A twin-fluid atomizer of mold-wash slurry is designed for this project. New atomizer is equipped with the existing manufacturing facility to produce pipes. Cast-iron pipes (.cent.125*L3000mm) are produced and the surface roughnesses of those are analysed by UBM. The average surface roughness of new products is 6.7.mu.m while the old products of sand-resin coating method have 17.0.mu.m of average surface roughness. The surface roughness of cast-iron pipe is improved very much than before.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.115-119
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• 1996

An estimation of surface roughness value is a very important and difficult issue in grinding process. The definition of the D.A.R.F(Dimensionless Average Roughness Factor) has been made including the absolute average and tile standard deviation that are the parameters of the AE(Acoustic Emission) sign. The theoretical equation of the surface roughness applying the D.A.R.F has been derived from the regressive analysis and specified with respect to the availability through the experimental approach on the machine.