• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.125-126
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• 2009

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.28-30
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• 2000

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.623-624
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• 2007

• Proceedings of the Korean Society of Laser Processing Conference
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• 2001.11a
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• pp.55-59
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• 2001

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.164-165
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• 1999

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.210-211
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• 2002

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.9-18
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• 2008

Curling is caused by the difference in the temperature and humidity by the depth of the slab in Jointed Plain Concrete Pavement. Slab curvature shape and size change due to curling exert a profound influence on the internal stress and roughness of the pavement, affecting structural and functional performance of the pavement. Direct measurement of the slab curvature entails many problems. Many measuring instruments have to be installed at the early-stage of the pavement construction, and the behavior of the slab curvature needs to be measured accurately from the early-stage. Moreover, the cost and technical difficulty are very formidable to measure the slab curvature. This study develops a measurement method for slab curvature in jointed concrete pavement at any given time by applying Power Spectrum Density Analysis and Inverse Fast Fourier Transformation to the profile data, that can be easily obtained at the construction field site. The effectiveness of this developed method is verified by measuring the profile data of the test road of jointed concrete pavement at an inland central expressway by the hour and by examining the result of extracting the slab curvature shape from this profile data. Additionally, the profile data of CRCP(Continuously Reinforced Concrete Pavement) sections on the same expressway were obtained and analyzed at the same time. The validity of the method developed for the slab curvature shape extraction is verified by comparing the result from the analysis of the profile data of CRCP sections with that from the analysis of the prof1Ie data of jointed concrete pavement sections.

• Journal of the Korean Solar Energy Society
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• v.30 no.4
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• pp.79-85
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• 2010

The uncertainty in WindCube LIDAR measurements, which are specific to wind profiling at less than 200m above ground levelin wind resource assessments, was analyzed focusing on the error caused by its volume sampling principle. A two-month SODAR measurement campaign conducted in an urban environment was adopted as the reference wind profile assuming that various atmospheric boundary layer shapes had been captured. The measurement error of LIDAR at a height z was defined as the difference in the wind speeds between the SODAR reference data, which was assumed to be a virtually true value, and the numerically averaged wind speed for a sampling volume height interval of $z{\pm}12.5m$. The pattern of uncertainty in the measurement was found to have a maximum in the lower part of the atmospheric boundary layer and decreased with increasing height. It was also found that the relative standard deviations of the wind speed error ratios were 6.98, 2.70 and 1.12% at the heights of 50, 100 and 150m above ground level, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.7 s.166
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• pp.1129-1138
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• 1999

[$Moir\acute{e}$] technique is now being extensively investigated as a fast non-contact means of three-dimensional profile measurement especially for reverse engineering. One problem with $moir\acute{e}$ technique is so called $2\pi$-ambiguity problem that limits the maximum step height difference between two neighboring sampling points to be less than half the equivalent wavelength of $moir\acute{e}$ fringes. In this investigation, a new two-wavelength scheme of projection $moir\acute{e}$ topography is proposed and tested to cope with the $2\pi$-ambiguity problem. Experimental results are discussed to assess the new method in measuring large objects with high step discontinuities.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.48-52
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• 2001

In this paper presents an accurate AFM used that is free from the Z-directional distortion of a servo actuator is described. Two mathematical correction methods by the in-situ self-calibrationare employed in this AFM. One is the method by the integration, and the other is the method by inverse function of the calibration curve. The in situ self-calibration method by the integration, the derivative of the calibration curve function of the PZT actuator is calculated from the profile measurement data sets which are obtained by repeating measurements after a small Z-directional shift. Input displacement at each sampling point is approximately estimated first by using a straight calibration line. The derivative is integrated with reference to the approximate input to obtain the approximate calibration curve. Then the approximation of the input value of each sampling point is improved using the obtained calibration curve. Next the integral of the derivative is improved using the newly estimated input values. As a result of repeating these improving process, the calibration curve converges to the correct one, and the distortion of the AFM image can be corrected. In the in situ self-calibration through evaluating the inverse function of the calibration curve, the profile measurement data sets were used during the data processing technique. Principles and experimental results of the two methods are presented.