• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.209-210
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• 2006

• The Journal of Engineering Geology
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• v.14 no.2
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• pp.147-168
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• 2004

Purpose of this study is to quantitatively characterize the fracture roughness which was measured with a confocal laser scanning microscope. The roughness discrete data measured by confocal laser microscope were analyzed by spectral analysis and fast Fourier transform (FFT).The roughness data by used noise reduction filter were applied for fractal analysis to describe roughness features quantitatively. Artificial fractures created by Brazilian test on granites were used to measure fracture roughness under the confocal laser scanning microscope. Measurements were performed along three scan lines on each fracture surface. 36 scan lines were determined on 12 specimens in total. Features of roughness showed that coarse and medium grained granites tend to more rough features than those of fine grained granites. Continuous analog data of roughness is possible to described as discrete data of measure roughness with a fixed interval under the confocal laser microscope. Results of FFT with the measured data showed the highest values on the second harmonics. Distribution of average amplitude of second harmonics was observed 0.9853 in coarse grained granite, 1.0792 in medium grained granite and 0.6794 in fine grained granite. This indicates that the larger roughness has the higher energy of harmonics as the result of fractal analysis in low frequency zone.

• Science of Emotion and Sensibility
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• v.3 no.2
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• pp.9-15
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• 2000

직물 표면을 문지를 때 느끼는 촉감은 여러 가지 기계적인 자극이 손 끝에 전달되어 느끼게 되므로, 직물의 표면의 특성을 분석하는 것은 매우 중요하다. 그러므로 표면을 덮고 있는 잔털의 양과 숫자를 측정하는 방법을 개발하고 촉감해석에 사용할 수 있도록 하였다. 표면의 거칠기는 비접촉으로 측정하여 잔털의 성질까지 포함된 스펙트럼을 얻었으며 FFT 분석을 통해 직물의 표면 구조의 특징과 상관되는 결과를 확인하였다. KES-F System에서 측정한 Hand Value와 비교 분석한 결과, 표면 거칠기와 잔털량과 잔털수는 객관적인 촉감해석에 중요한 요소로 사용할 수 있었다.

• Journal of the Korean Geotechnical Society
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• v.25 no.4
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• pp.55-68
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• 2009

A new borehole roughness and verticality measurement system (BKS-LRPS) for rock socketed drilled shafts were developed and verified its field application. The stability of BKS-LRPS was verified for several field conditions, which included the effect of measuring unit shaking, the application of water/air calibration factors, and the resistance of high water pressure inside piles. Also, effective measurement distances for various conditions of turbidity were defined in the field by measuring borehole roughness and vertical alignment for 6 drilled shafts. Vertical alignments for all drilled shafts could be measured by BKS-LRPS. However, borehole roughness was not able to be measured due to high turbidity caused by RCD drilling processing. Based on the BKS-LRPS field verification, BKS-LRPS is the first borehole roughness and verticality measurement system applying both in the water and air.

• Tunnel and Underground Space
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• v.26 no.5
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• pp.384-395
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• 2016

Both the roughness measurement tests and the multi-stage shear tests were carried out on the 110 rock joint samples in order to investigate the influences of rock type, joint roughness and normal stress on the shear behaviour of rock joints. Test samples were composed of quartz porphyry, dacite, granite and gneiss, which were classified into three detailed groups according to their JRC values. Roughness parameters of rock joints were analyzed by roughness measurement tests, and shear characteristics were also investigated by multi-stage shear tests. Both peak shear strength and shear stiffness were increased as both joint roughness and normal stress were increased, whereas dilation angles showed lower values at the lower roughness and higher normal stress conditions. Besides, shear characteristics obtained from all tests of four different rock types with different rock strengths showed irrelevant details, therefore the influences of both joint roughness and normal stress on shear behaviors were found to be more considerable than the strength of intact rock. The results obtained from both multi-stage shear tests and direct shear tests were finally compared, where the dilation angles obtained from multi-stage shear tests were found to be valid only for the first normal stress conditions.

• Korean Journal of Materials Research
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• v.6 no.1
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• pp.3-11
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• 1996

대면적 정전 접합 장치를 고안 및 제작하여 Si과 glass를 정전 접합시켰다. 여러 온도에서 정전 접합 후 접합 면적을 측정하였으며 접합이 이루어진 경우 그 접합 면적이 90%를 넘었다. 접합시 전류를 측정하여 접합 강도와의 관계를 살펴보였다. 잔류 공공을 생성시키는 원인은 재료의 표면 거칠기 차이나 전극의 모양보다는 불순물 입자에 의한 것임이 밝혀졌고 같은 크기의 불순물 입자에 대한 공공의 크기는 접합 온도가 높을수록 감소하였다. 정전 접합에 미치는 불순물의 영향을 공공의 크기 및 불순물 입자의 크기를 측정하여 살펴보았다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.91-97
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• 2013

The input parameters of scattering models for computing the backscattering coefficients of earth terrains are mainly soil moisture and surface roughness. The backscattering coefficients of soil surfaces are more sensitive to surface roughness than soil moisture. In this study, we propose a precise measurement method for roughness parameters and analyze measurement errors. We measured surface roughness using a pin-board profiler(1 m, 0.5 cm interval) and a laser profiler(1 m, 0.25 cm interval). The measurement differences between two profilers in an average sense are 0.097 cm for root-mean-square (RMS) height and 1.828 cm for correlation length. The analysis of the correlation functions and relative errors shows that the laser measurements are more stable than the pin-board measurements. The differences of the calculated backscattering coefficients using a surface scattering model between pin-board and laser profiler measurements are less than 1 dB.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.21-27
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• 2014

The influence of the surface roughness on the natural convection heat transfers of a vertical plate were measured experimently. Mass transfer experiments instead of heat transfer experiment were performed based on the analogy. The piecewise electrodes were adopted to measure the local-average Nusselt number. Prandtl number was 2,014 and height of the plate was 0.154m The test results for a smooth surface showed similar heat transfer rate with the Le Fevre heat transfer correlation for a vertical plate. The Nusselt number increased with the roughness Rz $0.5{\sim}14.1{\mu}m$. The test results were presented by a simple correlation.

• Tunnel and Underground Space
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• v.9 no.4
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• pp.350-363
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• 1999

The precision cyclic shear test system was established to investigate the mechanical characteristics of rough rock joints under cyclic loading conditions. Laboratory cyclic shear tests were conducted for saw-cut joints and artificial rough rock joints using Hwangdeung granite and Yeosan marble. Surface roughness and aperture characteristics of specimens were examined by measuring surface topography using the laser profilometer. Peak shear strength, phase difference during loading and unloading, and anisotropic shear behavior were investigated throughout the cyclic shear test results. These features and their subsequent variations in each loading cycle are significantly dependent upon the second order asperities and the strength of intact rock. It was observed that degradation of asperities for rough rock joints under cyclic shear loading followed the exponential degradation laws of asperity angle and that the mechanism for asperity degradation would be different depending upon the normal stress level, roughness of joint surface and the loading stage.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.409-415
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• 2016

In this study, we test the effects of the surface roughness on the hydro efficiency of double-suction centrifugal pumps ($Q=70.7m^3/min$, H = 87 m). The original surface of the impeller and inner casing were coated, resulting in surface-roughness reductions ranging from $100{\sim}110{\mu}m$ to $0{\sim}0.08{\mu}m$. We conducted experimental studies to measure the efficiency of the pumps and operating-pump electro energy variations with different surface roughness values. The experimental results showed that the efficiency of the pumps increased by about 0.8~1.79% and the electric energy of the operating pump was reduced by around 4.38 ~ 6.08%. These results indicate that the performance of the pumps depend largely on the surface roughness of the impeller and inner casing, and by reducing the surface roughness, we can improve the efficiency of the pump and reduce costs by reducing the electric energy consumption.