• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• 제28권1호
• /
• pp.57-64
• /
• 2010

Measurements of deflection in load testing of structures are typically obtained with contact instrumentations such as LVDT (Linear-Variable Differential Transformer). LVDT only measure 1-dimensional deformation and in destructive testing is damage to instrumentation, thus prohibiting deflection when the beam is close to failure. Measurements of deflection using non-metric digital cameras are useful for load testing because there are very little cost or beam failure except for cheap targets and measurements in 3-dimensional deflection can obtained rapidly. In this research, deflection of concrete beam was measured using Nikon D80 DSLR camera, and the accuracy was evaluated with comparing the outputs to the LVDT measurements. The results show that the accuracy of terrestrial photogrammetric measurements are ${\pm}$0.5mm, ${\pm}$0.5mm, ${\pm}$0.6mm for each X, Y, Z directions, and the RMSE of comparison to LVDT is ${\pm}$0.57mm.

• Journal of the Korean Society for Precision Engineering
• /
• 제16권10호
• /
• pp.35-44
• /
• 1999

The performance of interrupted cutting operations like milling is consideraly affected by cuter runout. In this study, cutter runout is selected as an important machining parameter for evaluation of machinability in ball-end milling and caused from misalignments of tool and holder, unbalanced mass of parts and tool deflection under machining. To evaluate the machinability due to cutter runout, the rotating accuracy of spindle, cutting force and surface roughness are measured. The rotating characteristics of spindle in each revolution speed were investigated by cutter runout in freeload. The predicted surface form of workpiece by measuring cutter runout data was compared with real surfaces. The results show that measuring runout with high response gap sensor is useful for studying the phenomenon of high-speed machining and the monitor surface form using in-process runout measurements in ball-end milling is possible.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• 제27권6호
• /
• pp.711-721
• /
• 2009

This study proposed digital close-range photogrammetric technique to measure deformation of I-plate-girder bridge. To compare deformation-measurement using the proposed method, a loading tester is used in the same time. As results, deviations of measuring values between the two methods range from 1mm to 2mm, and we could find-out simultaneously deflection and torsion of I-plate girder by repeated load of train. Then this study verified a measuring feasibility of I-plate-girder deformation by the proposed method. This may be alternative method of precise-stability inspection and manpower inspection.

• Tribology and Lubricants
• /
• 제28권5호
• /
• pp.203-211
• /
• 2012

Atomic force microscopy (AFM) has been used as a tool, not only for imaging surfaces, but also for measuring surface forces and mechanical properties at the nano-scale. Force calibration is crucial for quantitatively measuring the forces that act between the AFM probe of a force sensing cantilever and a sample. In this work, the lateral force calibrations of a V-shaped cantilever were performed using the finite element method, multiple pivot loading, and thermal noise methods. As a result, it was shown that the multiple pivot loading method was appropriate for the lateral force calibration of a V-shaped cantilever. Further, through crosschecking of the abovementioned methods, it was concluded that the thermal noise method could be used for determining the lateral spring constants as long as the lateral deflection sensitivity was accurately determined. To obtain the lateral deflection sensitivity from the sticking portion of the friction loop, the contact stiffness should be taken into account.

• Current Optics and Photonics
• /
• 제7권4호
• /
• pp.337-344
• /
• 2023

Three-point bending is the main method for measuring the elastic modulus of a thin plate. Although various displacement transducers may be used to measure the bending, these are single-point measurements, and it is difficult to eliminate the error caused by eccentric load and shear force. Error-correction models for the elastic modulus of quartz glass using digital speckle interferometry are proposed for eccentric load and shear force. First, the positional misalignment between maximum deflection and load is analyzed, and the error caused by eccentric load is corrected. Then, the additional displacement caused by shear force at different positions of the quartz glass plate is explored. The effect of shear deformation is also corrected, by measuring two points. Since digital speckle interferometry has the advantage of full-field measurement, it can simultaneously obtain deflection data for multiple points to realize error correction. Experimental results are presented to demonstrate that the proposed model can effectively correct the measurement error of the elastic modulus.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 한국공작기계학회 1996년도 춘계학술대회 논문집
• /
• pp.183-187
• /
• 1996

On the machine measuring system composed of touch trigger probes, a DNC module, a CMM module, an analysis module and a man-machine interface unit was developed. Measuring accuracy is affected by working accuracy of the on the machine measuring system. The working accuracy of the system is due to geometric errors of th machine tool, servo errors of feed drives and positioning errors of probes. In order to compensate for the measuring errors due to the working accuracy, a calibration module was developed. The measuring automation system was realized with the on the machine measuring system and an IBM-PC on the machine center through a RS-232C. It turns the machining machine (CMM). The system is used for dimensional checking of machined components. initial job setup, part identification, identification of machining errors due to deflection and wear of tools. cutter run out, and calibration of machine tools. A horizontal machining center equipped with FANUC OMC wre used for verification of the system. The validity and reliability of the system. The validity and reliability of the system were confirmed through a series of experiments with gage blocks, ring gages, comparison measurement with a commercial CMM, and so on.

• The Journal of Engineering Geology
• /
• 제19권2호
• /
• pp.191-203
• /
• 2009

The effect of stabilizing piles on cut slopes is checked and the behavior of slope soil and piles are observed throughout the year by field measurements on the large-scale cut slopes. First of all, the behavior of the slope soil was measured by inclinometers during slope modification. Landslides occurred in this area due to the soil cutting for slope modification. The horizontal deformations of slope soil are gradually increased and rapidly decreased at depth of sliding surface. As the result of measuring deformation, the depth of sliding surface below the ground surface can be known. Based on the measuring the depth of the sliding surface, some earth retention system including stabilizing piles were designed and constructed in this slope. To check the stability of the reinforced slope using stabilizing piles, an instrumentation system was installed. As the result of instrumentation, the maximum deflection of piles is measured at the pile head. It is noted that the piles deform like deflection on a cantilever beam. The maximum bending stress of piles is measured at the soil layer. The pile above the soil layer is subjected to lateral earth pressure due to driving force of the slope, while pile below soil layer is subjected to subgrade reaction against pile deflection. The deflection of piles is increased during cutting slope in front of piles for the construction of soil nailing. As a result of research, the effect and applicability of stabilizing piles in large-scale cut slopes could be confirmed sufficiently.

• Coupled systems mechanics
• /
• 제4권4호
• /
• pp.279-295
• /
• 2015

The article presents a theoretical-experimental approach developed for modeling the coefficient of sliding friction in the dynamic system tool-workpiece in slide diamond burnishing of low-alloy unhardened steels. The experimental setup, implemented on conventional lathe, includes a specially designed device, with a straight cantilever beam as body. The beam is simultaneously loaded by bending (from transverse slide friction force) and compression (from longitudinal burnishing force), which is a reason for geometrical nonlinearity. A method, based on the idea of separation of the variables (time and metric) before establishing the differential equation of motion, has been applied for dynamic modeling of the beam elastic curve. Between the longitudinal (burnishing force) and transverse (slide friction force) forces exists a correlation defined by Coulomb's law of sliding friction. On this basis, an analytical relationship between the beam deflection and the sought friction coefficient has been obtained. In order to measure the deflection of the beam, strain gauges connected in a "full bridge" type of circuit are used. A flexible adhesive is selected, which provides an opportunity for dynamic measurements through the constructed measuring system. The signal is proportional to the beam deflection and is fed to the analog input of USB DAQ board, from where the signal enters in a purposely created virtual instrument which is developed by means of Labview. The basic characteristic of the virtual instrument is the ability to record and visualize in a real time the measured deflection. The signal sampling frequency is chosen in accordance with Nyquist-Shannon sampling theorem. In order to obtain a regression model of the friction coefficient with the participation of the diamond burnishing process parameters, an experimental design with 55 experimental points is synthesized. A regression analysis and analysis of variance have been carried out. The influence of the factors on the friction coefficient is established using sections of the hyper-surface of the friction coefficient model with the hyper-planes.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• 제5권3호
• /
• pp.22-30
• /
• 1996

In order to compensate for out-of-straightness of shafts, an automatic straightening process composed of an automatic measuring module, an automatic control unit and operating softwares was developed with a hydraulic press. The out-of-sraightness of each shaft was measured automatically in the measuring stage. An optimal pressure point was determined to minimize TIR value of the shaft according to press count of 3-points bending process. In the geometric adaptive control procedure, punch stroke and springback of the shaft were predicted by an observer using on-line measured values of press force and deflection amount I each press count. An automatic straightening machine was realized with the measuring module, the GAC module, PLD, IBM-PC and the operating software on the hydraulic press. the validity of the proposed straightening process was confirmed through a series of experiments with cam shafts.

• Journal of the Korean Society for Precision Engineering
• /
• 제25권7호
• /
• pp.87-94
• /
• 2008

The displacement sensor using optical pickup head is presented. The measuring principle of optical pickup head in focusing direction is adopted to measure displacement. The preliminary tests were carried out to verify the feasibility of the optical pickup head as a displacement sensor and optical pickup head showed about $8\;{\mu}m$ measuring range and 10nm resolution. The methodology to expand measuring range is proposed and proved its validity. The proposed displacement sensors are applied to AFM(Atomic Force Microscope) probe head to measure the deflection of micro-cantilever.