• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.145-152
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• 1999

This paper presents the principle and experimental results of a non-contact surface roughness measurement by means of screen projected pattern of lase beam reflected from a polished surface. In the reflected laser beam pattern especially from a fine surface like ground or polished one, light intensity varies from the center fo the image to its boundary as the Gaussian distribution. The standard deviation of a light intensity distribution is assumed to be a good non-contact estimator for measuring the surface roughnes, because the light reflectivity is known to be well related with the surface roughness. This method doesn't need to discriminate between the specularly reflected light and the diffusely reflected one, whereas the scattered laser intensity method must do. Nor it needs to adjust the change of light intensity caused by environmental lights or specimen materials. Reflected laser beam pattern narrowly spreads out in the vertical direction to tiny scratches on the polished surface due to abrasives. The deeper the scratch the more the dispersion, which means the rougher surface. The standard deviation of the pattern is nearly in proportion to the surface roughness. Measurement errors by this method are shown to be below 10 percent compared with those obtained by a common contact method. The inclination of measuring unit from the normal axis causes the measurement errors up to 10 percent for an angle of 4 degree. Therefore the proposed method can be used as an on-the-machine quick roughness estimator within 10 percent measurement error.

• Analytical Science and Technology
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• v.22 no.2
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• pp.141-147
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• 2009

A laser induced breakdown spectroscopy (LIBS) measurement was carried out to derive an optimized measurement condition with a high reproducibility and to grow a plasma sphere to 20 mm high under a 600 mtorr vacuum in order to improve an accuracy of measurement. The measurement of the plasma was taken at a 6.0 mm distance, in the direction of a plasma sphere, from a sample. This location belongs to the outer sphere region in the plasma. The calibration curve of 'Ni' and 'Cu' was acquired by the signal intensity ratio and the atomic ratio for the samples, and linear regression of 'Cu' was $R^2$=0.9886, and the linear regression of 'Ni' was $R^2$=0.9988. The accuracy of LIBS was improved pre-existence as the measurement error of 'Ni' was 0.78%.

• The Transactions of the Korea Information Processing Society
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• v.13 no.9
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• pp.468-473
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• 2024

Excavation work in urban areas can induce ground deformation, which may damage nearby infrastructure. Such ground deformation can result in displacement of paving blocks near the construction site. Accurate measurement of these displacements can serve as an indicator for assessing the potential risks associated with ground deformation. This paper proposes a robust and efficient method for paving block displacement measurement using a 3D laser line sensor mounted on an Unmanned Ground Vehicle (UGV). The proposed method consists of two stages: 2D projection based object detection and measurement through the CPLF algorithm. Experimental results demonstrate that the CPLF algorithm is more efficient compared to the PLF algorithm, achieving an error of 1.36 mm and a processing time of 10.76 ms, confirming that the proposed method ensures robust online measurements with high accuracy in real-world environments with various types of paving blocks and environmental factors using a 3D laser line sensor on a UGV.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.50-50
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• 2000

In this paper, a new measuring system is :proposed which can measure the fine 6-DOF displacement of rigid bodies. Its measurement principle is based on detection of laser beam reflected from a specially fabricated mirror that looks like a triangular pyramid having an equilateral cross-sectional shape. The mirror has three lateral reflective surfaces inclined 45$^{\circ}$ to its bottom surface. We call this mirror 3-facet mirror. The 3-facet mirror is mounted on the object whose 6-DOF displacement is to be measured. The measurement is operated by a laser-based optical system composed of a 3-facet mirror, a laser source, three position-sensitive detectors(PSD). In the sensor system, three PSDs are located at three corner points of a triangular formation, which is an equilateral triangular formation tying parallel to the reference plane. The sensitive areas of three PSDs are oriented toward the center point of the triangular formation. The object whose 6-DOF displacement is to be measured is situated at the center with the 3-facet mirror on its top surface. A laser beam is emitted from the laser source located at the upright position and vertically incident on the top of the 3-fatcet mirror. Since each reflective facet faces toward each PSD, the laser beam is reflected at the 3-facet mirror and splits into three sub-beams, each of which is reflected from the three facets and finally arrives at three PSDs, respectively. Since each PSD is a 2-dimensional sensor, we can acquire the information on the 6-DOF displacement of the 3-facet mirror. From this principle, we can get 6-DOF displacement of any object simply by mounting the 3-facet mirror on the object. In this paper, we model the relationship between the 6-DOF displacement of the object and the outputs of three PSDs. And, a series of simulations are performed to demonstrate the effectiveness of the proposed method. The simulation results show that the proposed sensing system can be an effective means of obtaining 3-dimensional position and orientation of arbitrary objects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.44-48
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• 2002

In this paper, we demonstrated the simultaneous measurment of triple parameters such as strain, temperature, and vibration using single FBG/EFPI hybrid sensor. The FBG/EFPI sensor system for the strain and temperature measurement and the EFPI sensor system for the the vibration measurement were combined by a wavelength division multiplexer. The optical source of FBG/ EFPI sensor system is a wavelength-swept fiber laser(WSFL) and that of an EFPI sensor system is a laser diode. We performed the simultaneous measurement of thermal strain, temperature, and vibration of a aluminum beam placed in a thermal chamber and validated the efficiency of the constructed measurment system.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.823-825
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• 2003

A sensor system was designed to measure real time vibro displacement of civil structure. The He-Ne laser is used for the displacement measuring method, because it guarantees short time stabilization, long time output power stability. Also, it guarantees simple maintenances and repairs under actual using condition. The line CCD image sensor(Tcd-142d) is used to detect the displacement of Ne-Ne laser responding to the vibro of civil structure. For accurate measurement and comparison, CDP-50 is used. Usually CDF-50 (Strain type displacement device) is used for the standard correction device of optical measurement equipments. The data processing part is consists of Optical sensor part, Wireless data transmission device, DAQp-1200, and LapView program. The displacement data of vibro from optical sensor part inputted to wireless data transmission device and then transmitted to DAQp-1200 in main control room. DAQp-1200 performs A/D conversion for the receiving data. After that the converted data inputted to computer system using LapView program for user display. The significance of this paper is to develope a convenient, accurate and lost saving real time displacement measurement system for the civil structure.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.287-293
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• 2018

This paper presents a satellite relative navigation strategy for formation flying, which chooses an appropriate navigation algorithm according to the operating environment. Not only global positioning system (GPS) measurements, but laser measurements can also be utilized to determine the relative positions of satellites. Laser data is used solely or together with GPS measurements. Numerical simulations were conducted to compare the relative navigation algorithm using only laser data and laser data combined with GPS data. If an accurate direction of laser pointing is estimated, the relative position of satellites can be determined using only laser measurements. If not, the combined algorithm has better performance, and is irrelevant to the precision of the relative angle data between two satellites in spherical coordinates. Within 10 km relative distance between satellites, relative navigation using double difference GPS data makes more precise relative position estimation results. If the simulation results are applied to the relative navigation strategy, the proper algorithm can be chosen, and the relative position of satellites can be estimated precisely in changing mission environments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.113-115
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• 2010

In this study, ZnO films have been grown on PES(polyethersu]fone) substrate by PLD(pulsed laser deposition) and characterized as a change of laser density and substrate temperature. Growing conditions were changed with substrate temperatures ranging from 50 to $200^{\circ}C$ and laser densities ranging from $0.2\sim0.4 J/cm^2$. Optical and structural properties were measured by XRD, SEM, AFM, PL measurement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.227-228
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• 2016

Terrestrial laser scanning (TLS) technology is being applied to various fields such as the soil volume calculation and the displacement measurement of terrain, tunnels and dams. This study develops a 3D terrain processing platform for automated earth work using a terrestrial laser scanning data as the software prototype. The developed software provides cells with geo-technical information for planning work to an integrated system.

• Journal of Welding and Joining
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• v.17 no.3
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• pp.26-35
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• 1999

On the laser weld production line, a slight alteration of the welding condition changes the bead size and the strength of the weldment. The measurement system is produced by using three photo-diodes for detection of the plasma and spatter signal in $CO_2$ laser welding. The relationship between the sensor signals of plasma or spatter and the bead shape, and the mechanism of the plasma and spatter were analyzed for the bead size estimation. The penetration depth and the bead width were estimated using the multiple regression analysis.