• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.150-153
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• 2003

Longitudinal strains({$varepsilon}_x$) of the core and skin layers in glass fiber reinforced plastic(GFRP) cross-ply composite laminates have been studied using the embedded optical fiber sensor of totally-reflected extrinsic Fabry-Perot interferometer(TR-EFPI). Foil-type strain gauges bonded on both the upper and lower surfaces were used for the measurement of the surface strains. Both TR-EFPI sensor and strain gauge bonded on the specimen surface showed excellent agreement within -0.0086 ~ +0.0302% strain. It was shown that values of {$varepsilon}_x$ in the interior of the surface layer and the core layer measured by embedded TR-EFPI sensor was significantly higher than that of the specimen surface measured by strain gauges. The experimental results were ascertained with finite element analysis. Embedded TR-EFPI optical fiber sensor could measure accurately the internal strains which were different from the surface.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.108-116
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• 2014

The proper stress history measurement should be conducted in order to examine the accurate cause of fatigue cracks or the fatigue safety in the steel bridge. Only one strain gauge is generally installed in the field for the stress history examination because of the field circumstances, economic feasibility, workability, and so on. However, this method may not consider the actual size of the specific structure, the gauge length, and the affect of stress concentration in the welded joint. In addition, it is difficult to apply for the stress analysis. Therefore, this study suggests improvements that are a great number of gauge installations, the gauge location adjustment, and the use of the minimum length gauge. It is drived the correlative equation of strain for the distance between the welding toe and the strain gauge installation, and compare correlative equation with equation of IIW. Also, this study could estimate the remaining life and fatigue damage of bridge in service by selecting the suitable stress category. In conclusion, it is possible to understand the member which is high in the fatigue cracks, and the quantitative relations between the welding toe and the strain gauge installation distances. The proposed approach in this study can make an more accurate fatigue damage and a remaining life prediction so that the improved method should be applied in measuring the strain of bridges from now on.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1382-1390
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• 1995

Electronic Speckle Pattern Interferometry (ESPI) with a CW laser, a video system and an image processor was utilized to measure the in-plane displacement. Unlike traditional strain gauges or Moire method. ESPI method measure the in-plane displacement on real time with out any surface preparation on surface attachment. The specimen has a crack of 10*0.1 mm in the middle of plate and strain gauge was also attached on that surface to compare with ESPI method. This study reveled the ESPI method to measure the displacement and distribution of strain in the specimen. It was shown in tensile tests that the measurement by ESPI method was comparable with strain gauge.

• Journal of the Korean Society for Nondestructive Testing
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• v.10 no.1
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• pp.65-72
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• 1990

Comparison of acoustic emission, ultrasonic testing and crack gauge in 3-point bending testing have been studied. As the results, COD is indirectly assumed by strain gauge rate and grid pitch width when crack gauge grid is out. Acoustic emission is qualitatively able to measure crack growth by total count but ultrasonic testing has a difficulty in measuring it because of echo height fluctuation according to the change and pressure of UT. probe.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.9
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• pp.72-80
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• 2019

In this task, the tool dynamometer design and manufacture, and the Ansys S/W structural analysis program for tool attachment that satisfies the cutting force measurement requirements of the tool dynamometer system are used to determine the cutting force generated by metal cutting using 3-axis static structural analysis and the LabVIEW system. The cutting power in a cutting process using a milling tool for processing metals provides useful information for understanding the processing, optimization, tool status monitoring, and tool design. Thus, various methods of measuring cutting power have been proposed. The device consists of a strain-gauge-based sensor fitted to a new design force sensing element, which is then placed in a force reduction. The force-sensing element is designed as a symmetrical cross beam with four arms of a rectangular parallel line. Furthermore, data duplication is eliminated by the appropriate setting the strain gauge attachment position and the construction of a suitable Wheatstone full-bridge circuit. This device is intended for use with rotating spindles such as milling tools. Verification and machining tests were performed to determine the static and dynamic characteristics of the tool dynamometer. The verification tests were performed by analyzing the difference between strain data measured by weight and that derived by theoretical calculations. Processing test was performed by attaching a tool dynamometer to the MCT to analyze data generated by the measuring equipment during machining. To maintain high productivity and precision, the system monitors and suppresses process disturbances such as chatter vibration, imbalances, overload, collision, forced vibration due to tool failure, and excessive tool wear; additionally, a tool dynamometer with a high signal-to-noise ratio is provided.

• The Journal of Advanced Prosthodontics
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• v.5 no.3
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• pp.312-318
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• 2013

PURPOSE. The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. MATERIALS AND METHODS. A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment completely disappeared. In the second group, only nodules detectable to the naked eye were removed. The third group employed screw-retained design and specimens were generated by computer-aided design/computer-aided manufacturing system (n=10). Four strain gauges were fixed on the measurement model mesially and distally to the implants. The strains developed in each strain gauge were recorded during fixation of specimens. To compare the difference among groups, repeated measures 2-factor analysis was performed at a level of significance of ${\alpha}$=.05. RESULTS. The absolute strain values were measured to analyze the magnitude of strain. The mean absolute strain value ranged from 29.53 to 412.94 ${\mu}m/m$ at the different strain gauge locations. According to the result of overall comparison, the cement-retained prosthesis groups exhibited significant difference. No significant difference was detected between milled screw-retained prostheses group and cement-retained prosthesis groups. CONCLUSION. Within the limitations of the study, it was concluded that the cement-retained designs do not always exhibit lower levels of stress than screw-retained designs. The internal adjustment of a cement-retained implant restoration is essential to achieve passive fit.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.6
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• pp.529-535
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• 2016

This study focuses on the comparison of measured data from 6-DOF motion sensor and strain gauge installed in the IBRV ARAON during 2015 summer voyage in the Arctic. Procedures to calculate the global ice load from MotionPak II inertial measurement system and the local load from stain gauge system are discussed. The ship's speed and peak load are determined in the concept of an ice collision "event". It is found that the peak values in the global ice calculated form whole ship motion analysis fall in the range of 1.5~3 times of the local ice load based in strain gauge measurement.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.6
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• pp.489-494
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• 2014

Estimation of correct ice load under various operating conditions is important during the design and the operation stages of an icebreaker. Normal operating conditions are expected from the official field ice trials and also from general ice transit action. In this paper ice load for the Korean icebreaking research vessel, ARAON, under normal operating condition, is discussed. Published ice load data from full-scale sea trials of six icebreakers were analysed to derive an empirical ice load prediction formula. The IBRV ARAON had sea ice trials during 2010 and 2012 summer season. Strain gauge signal were recorded during her icebreaking voyage and the measured strain data were converted to the equivalent hull stress values. The effect of ARAON's speed in ice and the hull stresses are investigated. By comparing the empirical formula and ice load calculation based von measured data, it is recommended to use the empirical ice load estimation formula for the initial design stage.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.13-22
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• 2002

This paper presents characteristics of CrOx thin-film Strain gauge pressure sensors, which were deposited on SUS630 diaphragm by DC reactive magnetron sputtering in an argon-Oxide atmosphere(Ar-(10%)$O_2$). The optimized condition of CrOx thin-film strain gauges were thicknessrange of 2500$\AA$ and annealing condition ($350^{\circ}C$, 3 hr) in Ar-10 %$O_2$deposition atmosphere. Under optimum conditions, the CrOx thin-films for strain gauge is obtained a high resistivity, $\rho$=156.7$\mu$$\Omega$cm, a low temperature coefficiect of resistance, TCR=-86 ppm/$^{\circ}C$ and a high temporal stability with a good longitudinal, 15. The output sensitivity of pressure sensor obtained is 2.46㎷/V and the maximum non-linearity is 0.3%FS and hysteresis is less than 0.2%FS. The output characteristics of pressure transmitter obtained is 4~20㎃ and total accuracy is less than $\pm$0.5%FS. In those conclusions, CrOx thin film pressure sensors is quite satisfactory for many applications in industrial electronics.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.303-308
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• 2004

This paper descibes on the characteristics of Ta-N(tantalum nitride) ceramic thin-film strain gauges which were deposited on Si substrates by DC reactive magnetron sputtering in an argon-nitrogen atmosphere (Ar-$(4{\sim}16%)N_{2}$) for high-temperature applications. These films were annealed in $2{\times}10^{-6}$ Torr vacuum furnace at the range of $500{\sim}1000^{\circ}C$. Optimum deposition atmosphere and annealing temperature were determined at $900^{\circ}C$ for 1 hr. in 8% $N_{2}$ gas flow ratio. Under optimum formation conditions, the Ta-N thin-film for strain gauges was obtained a high-resistivity of $768.93{\mu}{\Omega}{\cdot}cm$, a low temperature coefficient of resistance (TCR) of -84 ppm/$^{\circ}C$ and a good longitudinal gauge factor (GF) of 4.12.