• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.139-149
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• 2001

The effects of the cutting conditions on the surface roughness of workpiece in turning were studied in this paper. The workpieces made of carbon steel SM20C and SM45C were tamed without the support of the tailstock center. Cutting conditions were changed in three or flour steps in each parameter and cutting fluid was used. The surface roughness results of tests were measured and the effects of the cutting conditions were analyzed by the method of analysis of variance. The summary of the experimental research is as follows. The main parameters were cutting speed, fred-rate, depth of cut, and the interactions between speed and fled-rate, speed and depth of cut, and fred and depth of cut. As cutting speed increased, surface roughness showed lower value. The surface roughnesses of feed-rate 0.102 mm/rev and 0.147 mm/rev were better than those of feed-rate 0.05 mm/rev and 0.2 mm/rev.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.2
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• pp.147-153
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• 2014

This study was performed to evaluate the effect of surface roughness on pump performance. To this end this, using commercial codes, ANSYS CFX and BladeGen, we simulated pump performance in terms of efficiency, head and shaft power, both with and without surface roughness. Finally simulation and experiment results were compared for a quantitative analysis. The results of this comparison showed that surface roughness led to an about 7% reduction in pump efficiency.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.3
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• pp.77-82
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• 2014

In this study, we carried out the interrupted cutting of carbon steel for a machine structure (SM45C) with a CVD-coated tool and conducted an ANOVA test and a confidence interval analysis to find factors influence the surface roughness and to obtain a regression equation. We found that factor which mostly affects the surface roughness during interrupted cutting was the feed rate. The cutting speed and depth of the cut only had small effect on the surface roughness. From the result of a multi-regression analysis during an interrupted cutting experiment, we obtained regression equation. Its coefficient of determination was 0.918, indicating that the regression equation was predictable. Compared to continuous cutting, if the feed rate increases, the surface roughness will also increase during interrupted cutting.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.4
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• pp.432-440
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• 2007

In this study, we have investigated the closure behavior of fatigue cracks in SAPH440 steel plates under a mixed-mode I+II loading. A crack image capturing system as a direct measuring method was used to measure the closure levels at a crack tip. The crack closure levels in the fluctuation and stable sections were increased with the increase of the mode mixture ratio. The mode mixture ratio independent fatigue crack propagation rates equation was calculated by considering mixed-mode crack closure levels. The equation was examined according to the application method of crack opening ratio. The fracture surface analysis by C-scan method was also performed in order to investigate the closure mechanism and propagation mode of crack under the mixed-mode I+II loading. The crack closure under the mixed mode I+II is confirmed as a surface roughness closure by the quantitative analysis of fracture surface using the proposed surface roughness parameter.

• Tribology and Lubricants
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• v.27 no.6
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• pp.326-331
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• 2011

The purpose of this paper is to analyze and discuss the effects of surface roughness by comparing the elastohydrodynamic lubrication(EHL) analysis of smooth surface and rough surface as the ball bearing. In order to do this, The average flow model is adapted for the interaction of the flow rheology of lubricant and surface roughness. The average Reynolds equation and the related flow factor which describes the coupled effects of surface roughness and flow rheology, the viscosity-pressure and density-pressure relations equations, the elastic deformation equation, and the force balance equation are solved simultaneously. The results show that effects of surface roughness on the film thickness and pressre distribution should be considered especially in EHL contact problems.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.57-68
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• 1999

This paper summarizes the results of a study which uses the recently developed Optical Profile Microscopy technique (Dove and Frost, 1996) as the basis for investigating the role of geomembrane surface roughness on the shear mechanism of geomembrane/geotextile interfaces. The alternative roughness parameters which consider the direction of shearing are described. These directional parameters are compared with the existing roughness parameters, and the relationship between these directional and non-directional parameters are investigated. Then, the relationship between interface shear strength and surface roughness quantified at the interface is investigated. The results show that interface friction can be quantitatively related to the surface roughness of the geomembrane. The peak and residual interface strengths increase dramatically through the use of textured geomembranes as opposed to smooth geomembranes. For the smooth geomembranes, the sliding of the geotextile is the main shear mechanism. For the textured geomembranes, the peak interface strength is mainly mobilized through the micro-texture of the geomembrane, however, the residual interface strength is primarily attributed to macro scale surface roughness which pulls out and breaks the filaments from the geotextile. The results of this study can be extended to the other interfaces such as joints in rock mass, and also can be used to provide a quantitative framework that can lead to a significantly improved basis for the selection and design of geotextiles and geomembranes in direct contact.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6B
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• pp.345-354
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• 2012

The main objective of this study is evaluating experimentally roughness coefficients of the Korean riparian vegetations based on the n-VR analysis to suggest the practical guideline for Manning's roughness coefficients for the channel design. Hydraulic experiments were conducted for Phragmites japonica Steud., Miscanthus sacchariflorus (Maxim.) Benth., and Phragmites communis Trin. under both submerged and un-submerged conditions, and the n-VR relationships are developed for each grass. Three vegetations tested in this study can be considered as same group showing similar roughness characteristics, though these grasses are strongly affected by vegetation stiffness. Vegetation roughness are also affected by the growth state of plants according to experimental results of Phragmites communis Trin.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.2
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• pp.11-18
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• 2008

Surface roughness is an important factor to evaluate machined parts in precision machining. This is the major measure of surface quality. This research sets up experiments to select the factors which affect surface roughness in the machining of inclined planes of aluminum. The levels of the selected experimental factors are chosen to evaluate the relationship between the surface roughness of the machined parts and machining parameters. This is to find out the optimal machining condition in the inclined planes. The objective of this research is to improve the surface roughness of the machined products by using the ANOVA analysis. The factors for the experiments are cutting speed, feed rate, cutting depth, and cutting width. The experimental levels of the factors are two for the cutting depth and width. For the cutting speed and feed rate, their levels are three because they are more sensitive for the surface roughness than the other two. The inclined planes are machined by 5-axis machining equipment.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.1
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• pp.55-63
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• 2021

The roughness of the road is an important factor directly connected to the ride comfort, and is an evaluation item for functional evaluation and pavement quality management of the road. In this study, data on the road surface were acquired using the latest 3D geospatial information construction technology of ground LiDAR, drone photogrammetry, and drone LiDAR, and the accuracy and roughness of each method were analyzed. As a result of the accuracy evaluation, the average accuracy of terrestrial LiDAR were 0.039m, 0.042m, 0.039m RMSE in X, Y, Z direction, and drone photogrammetry and drone LiDAR represent 0.072~0.076m, 0.060~0.068m RMSE, respectively. In addition, for the roughness analysis, the longitudinal and lateral slopes of the target section were extracted from the 3D geospatial information constructed by each method, and the design values were compared. As a result of roughness analysis, the ground LiDAR showed the same slope as the design value, and the drone photogrammetry and drone LiDAR showed a slight difference from the design value. Research is needed to improve the accuracy of drone photogrammetry and drone LiDAR in measurement fields such as road roughness analysis. If the usability through improved accuracy can be presented in the future, the time required for acquisition can be greatly reduced by utilizing drone photogrammetry and drone LiDAR, so it will be possible to improve related work efficiency.

• The Journal of Advanced Prosthodontics
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• v.7 no.3
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• pp.199-206
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• 2015

PURPOSE. The present study investigated the influences of various gypsum materials on the precision of fit of CAD/CAM-fabricated prostheses and analyzed their correlation with surface roughness. MATERIALS AND METHODS. The master model of the mandibular right first molar was replicated, and four experimental groups based on two types of Type IV stone (GC Fujirock EP, Die keen) and two types of scannable stone (Aesthetic-Basegold, Everest Rock) were created to include a total of 40 specimens, 10 in each group. The surface roughness of the working models for the respective experimental groups was measured. Once the zirconia cores had been fabricated, the marginal and internal fits were measured with a digital microscope using the silicone replica technique. The mean and standard deviation of the respective points of measurement were computed and analyzed through the one-way ANOVA and Tukey's HSD test. The correlation between surface roughness and the precision of fit of the zirconia core was analyzed using the Pearson correlation analysis (${\alpha}$=.05). RESULTS. The zirconia cores fabricated from the scannable stone working models exhibited a superior precision of fit as compared to those fabricated from the Type IV stone working models. The correlation analysis results showed a clear positive correlation between surface roughness and the precision of fit of zirconia cores in all of the experimental groups (P<.05). CONCLUSION. The results confirmed that the surface roughness of dental working models has a decisive influence on the precision of fit of zirconia cores.