• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.25-28
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• 2005

The optical fiber is known for the proper sensor which can accomplish the structural health monitoring, Fiber Bragg Grating sensors are being studied more than any other fiber optic sensors due to good multiplexing capabilities. But because the signal stability of FBG sensors can be influenced by the strain gradient, it needs to analyze signal of FBG sensors. Particularly acoording to strain gradient induced by structural geometry or cracks, the spectrum peak of the FBG sensor signal can be split easily. In this paper, the spectrum analysis of the FBG sensor signal was performed and the region of embedment of FBG sensors was determined in $H_2$ pressure vessel by numerical method.

• Journal of Sensor Science and Technology
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• v.22 no.3
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• pp.227-232
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• 2013

In this research, fiber-optic pressure sensors were fabricated with rugate-structured porous silicon (RPS) diaphragms coated with PMMA (Polymethyl-Methacrylate). The reflectance spectrum of the PMMA/RPS diaphragm was almost the same as that of uncoated RPS diaphragm. However the mechanical strength of the PMMA/RPS diaphragm increased more than that of the uncoated diaphragm. As a result, the fiber-optic sensor fabricated with PMMA/RPS diaphragm could successfully detect more high pressure difference without diaphragm damage than the highest detectable pressure difference of the sensor with normal RPS diaphragm. The response data of the fiber-optic sensor recorded as a function of pressure difference were fitted by theoretical curves. During this process, elastic moduli of the used PMMA/RPS diaphragms were obtained numerically. The dynamic response properties of the fiber-optic sensor were also investigated under continuous variation of the pressure difference conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.470-474
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• 2001

This paper describes the fabrication and characteristics of CrN thin-film type pressure sensors, in which the sensing elements were deposited on SuS. 630 diaphragm by DC reactive magnetron sputtering in an argon-nitride atmosphere(Ar-(10%)N$_2$). The optimized condition of CrN thin-film sensing elements was thickness range of 3500$\AA$ and annealing condition(300$\^{C}$, 3 hr) in Ar-10%N$_2$ deposition atmosphere. Under optimum conditions, the CrN thin-films for strain gauges is obtained a high resistivity, ρ=1147.65 $\mu$Ωcm, a low temperature coefficient of resistance, TCR=186ppm/$\^{C}$ and a high temporal stability with a good longitudinal, 11.17. The output sensitivity of fabricated CrN thin-film type pressure sensors is 2.36 mV/V, 4∼20nA and the maximum non-linearity is 0.4%FS and hysteresis is less than 0.2%FS.

• 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.27 no.6
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• pp.397-402
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• 2018

Proper seat design is critical to the safety, comfort, and ergonomics of automotive driver's seats. To ensure effective seat design, quantitative methods should be used to evaluate the characteristics of automotive seats. This paper presents a system that is capable of simultaneously monitoring body pressure distribution and surface deformation in a textile material. In this study, a textile-based capacitive sensor was used to detect the body pressure distribution in an automotive seat. In addition, a strain gauge sensor was used to detect the degree of curvature deformation due to high-pressure points. The textile-based capacitive sensor was fabricated from the conductive fabric and a polyurethane insulator with a high signal-to-noise ratio. The strain gauge sensor was attached on the guiding film to maximize the effect of its deformation due to bending. Ten pressure sensors were placed symmetrically in the hip area and six strain gauge sensors were distributed on both sides of the seat cushion. A readout circuit monitored the absolute and relative values from the sensors in realtime, and the results were displayed as a color map. Moreover, we verified the proposed system for quantifying the body pressure and fabric deformation by studying 18 participants who performed three predefined postures. The proposed system showed desirable results and is expected to improve seat safety and comfort when applied to the design of various seat types. Moreover, the proposed system will provide analytical criteria in the design and durability testing of automotive seats.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.9
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• pp.695-705
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• 2014

In this paper, two types of techniques for the prediction of radiated sound pressure due to vibration of a structure are investigated. The prediction performance using wave-number sensing technique is compared to that of conventional prediction method, such as Rayleigh's integral method, for the prediction of far-field radiated sound pressure. For a coupled plate, wave-number components are predicted by the vibration response of plate and the prediction performance of far-field sound is verified. In addition, the applicability of distributed sensors that are not allowable to Rayleigh's integral method is considered and these can replace point sensors. Experimental implementation verified the prediction accuracy of far-field sound radiation by the wave-number sensing technique. Prediction results from the technique are as good as those of Rayleigh's integral method and with distributed sensors, more reduced computation time is expected. To predict the radiated sound by the efficient configuration of structural sensors, composed(synthesized) mode considering sound power contribution is determined and from this size and location of sensors are chosen. Four types of sensor configuration are suggested, simulated and compared.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.1
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• pp.84-91
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• 2020

The APR1400 reactor stud holes can be stuck due to high temperatures, high pressure, prolonged engagement, and load changes according to pressure changes in the reactor. Threaded surfaces of a stud hole should be cleaned for the sealing of pressure in reactor vessel by removing any foreign materials which may exist in the stud holes. Human workers can access to the stud hole for the cleaning of stud holes manually, but the radiation exposure of human workers is increased. Robot is an effective way to work in hazardous area. So we introduced robot for the cleaning of stud holes. Localization of mobile robots is generally based on odometry, but with increased mileage, position errors can be accumulated. In order to eliminate cumulative error and to ensure stability of its driving, laser sensors and new control algorithm were utilized. The distance between the robot and the wall was measured by laser sensors, and the control algorithm was implemented so as to travel the desired trajectory by using the measured values from sensors. The performance of driving and hole sensing were verified through field application, and mobile robot was confirmed to be applicable to the APR 1400 NPP.

• Journal of Ocean Engineering and Technology
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• v.24 no.6
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• pp.30-33
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• 2010

This study presents the effect of filling ratio on sloshing impact pressure. The experiment was done with three filling ratios of 20%, 70%, and 95% of the tank height. The input of the motion was regular excitation. The total number of sensors in use were 53. They were installed on tank top and tank wall. The maximum pressures and the average of one third highest impact pressures for the whole pressure sensors were investigated. The result shows clearly the location of sensors which are exposed to the high impact pressures for different filling ratios. The characteristics of the impact patterns for three filling ratios were also examined.

• Journal of Sensor Science and Technology
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• v.33 no.3
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• pp.173-178
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• 2024

Development of pressure sensors for harsh environments with high pressure, humidity, and temperature is essential for many applications in the aerospace, marine, and automobile industries. However, existing materials such as polymers, adhesives, and semiconductors are not suitable for these conditions and require materials that are less sensitive to the external environment. This study proposed a pressure sensor that could withstand harsh environments and had high durability and precision. The sensor comprised a piezoresistor pattern and an insulating film directly formed on a stainless-steel membrane. To achieve the highest sensitivity, a pattern design method was proposed that considered the stress distribution in a circular membrane using finite element analysis. The manufacturing process involved depositing and etching a dielectric insulating film and metal piezoresistive material, resulting in a device with high linearity and slight hysteresis in the range of a maximum of 40 atm. The simplicity and effectiveness of this sensor render it a promising candidate for various applications in extreme environments.

• Wind and Structures
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• v.8 no.3
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• pp.179-196
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• 2005

This paper describes the application of a wireless data acquisition system to monitor wind pressures and velocities with absolute pressure sensors and an anemometer. The system was developed for future deployment, as part of a research effort currently underway to instrument coastal homes in Florida to monitor roof wind pressures during hurricanes. The proposed wireless system will replace the current system that involves a large amount of hardwired connections from the sensors to the data processing unit that requires labor intensive wiring and preparation of the home. The paper describes comparison studies and field tests to assess the performance of the system. The new system offers the advantages of light hardware, ease of installation, capacity for 48 hours of continuous data acquisition, good frequency and amplitude responses, and a relatively simple maintenance. However, the tests also show that the shape of the shell that has been previously used to protect the sensors might interfere with the proper measurement of the pressures.