• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.899-902
• /
• 2003

This study was tested for the bending stress analysis of hand spl int for Hemiplegic Patients. Hemiplegia was represented the stroke and the cerebral palsy. Hand splints of four materials was an Orthoplast hand splint, a Polypropylene hand splint, a Yogips hand splint and an Aluminum hand splint. The Stress Analysis system was made by the electronic oscilloscope, strain gage sensors, amplifier, A/D converter, PC with C program. It will be able to using the important data in spl int design. The results of analysis were obtained various different graphes and maximum data in an Orthoplast hand splint, a Polypropylene hand splint, a Yogips hand splint and an Aluminum hand spl int.

• Proceedings of the KSR Conference
• /
• 2006.11b
• /
• pp.1289-1292
• /
• 2006

The demand on a turnout layed on a bridge is rising owing to the increasing number of stations on the viaduct. And also the demand on a turnout with CWR is rising to upgrade running speed of the passing train. A CWR connected with turnout is subjected to additional axial force induced by the actions due to change in temperature, braking and starting force, and bending of the deck. But magnitude and distribution of the axial force in rails of turnout is not clear yet. So, in this study, a field measurement was conducted to know them. The strain gage method was adopted for field test. The FBG sensor for the strain measurement was used to ensure stability of test value and durability of gage for long term. It is expected that we can get data on the axial force in rail connected with turnout with respect to seasonal temperature change by the established field test system.

• Proceedings of the KWS Conference
• /
• 1990.11a
• /
• pp.82-86
• /
• 1990

A new method was investigated to measure the high current in resistance welding processes. A measuring unit was developed by using a strain gage attached on the outer surface of a steel ring. The steel ring was placed around a section of the secondary loop of the welding machine, and was deformed by electro-magnetic forces induced by the high welding current. The circumferential constituent of the ring deformation was then used to obtain a signal voltage proportional to the secondary welding current. The strain gage signal of ring deformation is enough to determine the welding current in resistance spot welding, especially when welded with direct current.

• Journal of the Korean Society for Precision Engineering
• /
• v.10 no.2
• /
• pp.86-94
• /
• 1993

In heavy industries forces which are exceeding the range of available force standard machines have to be measured. Force measuring system using build-up procedure can be applied to measure large forces efficiently. In this study strain gage type force sensors are designed and fabricated, and the build-up force measuring system with 4.5 MN capacity using the developed force sensors is 0.03% or less over the range of 600 kN .approx. 1.5 MN and the force measuring system is less than 0.06% or less over the range of 500 kN .approx. 4.5 MN.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1083-1084
• /
• 2011

• Composites Research
• /
• v.14 no.5
• /
• pp.12-19
• /
• 2001

In aircraft composite structures, structural defects such as matrix cracks, delaminations and fiber breakages are hard to detect if they are breaking out in operating condition. Therefore, to assure the structural integrity, it is desirable to perform the real-time health monitoring of the structures. In this study, a fiber optic sensor was applied to the composite beams to monitor failure and strain in real-time. To detect the failure signal and strain simultaneously, laser diode and ASE broadband source were applied in a single EFPI sensor using wavelength division multiplexer. Short time courier transform and wavelet transform were used to characterize the failure signal and to determine the moment of failure. And the strain measured by AEFPI was compared with the that of strain gage. From the result of the tensile test, strain measured by the AEFPI agreed with the value of electric strain gage and the failure detection system could detect the moment of failure with high sensitivity to recognize the onset of micro-crack failure signal.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.9
• /
• pp.1874-1881
• /
• 2002

Heat dissipation technology using the flow resonant phenomenon is a kind of a new concept in the heat transfer area. A vibration exciter is needed to enhance air flow mixing which has the natural shedding frequency of thermal system. A mechanical vibrating device for the air flow oscillation is introduced, which is driven by a moving coil actuator with a displacement estimator using strain gage. An analytical dynamic model for this mechanical vibration exciter is presented and its validity is checked by the comparison with experimental data. Values of some unknown system parameters in the analytic model are estimated through the system identification approach. Based on this mathematical model, the vibration exciter using strain displacement estimator is developed. During the experimental verification phase, it turns out the high modal resonant characteristics of a vibrating plate are a major barrier against obtaining a high bandwidth vibration exciter.

• Journal of Sensor Science and Technology
• /
• v.9 no.3
• /
• pp.163-170
• /
• 2000

Optical frequency modulated fiber optic interferometric sensor was developed to sense the mechanical quantities, such as displacement, strain, force etc. It has been difficult to distinguish whether the increase of the mechanical quantities or the decrease of the quantities measured by the conventional fiber optic interferometric sensors because their signals only have a sinusoidal wave pattern related to the change of mechanical quantities. In this study, in order to measure the mechanical quantifies with the distinction of the changing direction of the quantities, the fiber of optic Michelson interferometric sensor was simply constructed by the laser light modulated with saw tooth wave pattern. The output signal of the sensor was controlled as the sinusoidal wave. The signal processing was based on the counting of the wave number of the output signal during constant time duration. The strain was determined by the cumulative value of the wave number producted by the gage factor. In order to verify the strain measurement capability of this sensor, the strain increase-decrease test was performed by universal testing machine installed with the aluminum specimen bonded with the fiber optic sensor and electrical strain gage. In the result of the test, the strain from the fiber optic sensor had a good agreement with the values from the electrical strain gage.

• Journal of Industrial Technology
• /
• v.22 no.A
• /
• pp.169-176
• /
• 2002

The purpose of this paper is to investigate for strain measurement of concrete pavement slab at field. The early-age behaviors of concrete pavement were measured using the strain gages. From the static and dynamic wheel loading tests, the outputs from each gages were recorded. The measured data, also, was compared to those from finite element analysis. The static wheel loading tests were performed in twice, and the dynamic wheel loading tests were performed at the speed 10km-50km. The results could be summarized as follows: To embed the strain gage accurately and stably in concrete pavement, a chair and protective box must be used. The protective box must not be affected from the outside vibrating. From the results of early-age stram measurement, it was found that the strain varied at the maximum value of $180{\mu}{\varepsilon}$ From the results of static wheel loading tests, A1, A2 and B gages generally developed a consistent tendency When comparing the results from the measured at field and the calculated by FEM analysis, the data of A1 and B gages were similar to that from theory. The values from the field test were generally higher than that from the theory. From the results of dynamic wheel loading tests, it was known that the measured strain at field became smaller as the truck speed became faster, Indicating the maximum at the range of $12{\sim}13{\mu}{\varepsilon}$.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2003.04a
• /
• pp.388-399
• /
• 2003

Light losses in optical fibers are investigated by a fiber optic OTDR (Optical Time Domain Reflectometry) sensor system to develop fiber optic probes for structural strain measurement. The sensing fibers are manufactured 3 kinds of fibers: one is single mode fiber, and second is multimode fiber, and the third is low-cladding-index fiber. Fiber bending tests are performed to determine the strain sensitivity according to the strain of gage length of optical fibers. In the result of this experiments, the strain sensitivity of the single mode fiber was shown the highest value than others. The fiber optic strain probe was manufactured to verify the feasibility of the structural strain measurement. In this test, the fiber optic strain probe of the OTDR sensor could be easily made by the single mode fiber.