• Journal of KSNVE
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• v.8 no.4
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• pp.632-642
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• 1998

A method based on finite element discretization is developed for optimizing the polarization profile of PVDF film to create the modal transducer for specific modes. Using this concept, one can design the modal transducer in two-dimensional structure having arbitrary geometry and boundary conditions. As a practical means for implementing this polarization profile without repoling the PVDF film the polarization profile is approximated by optimizing electrode patterns, lamination angles, and poling directions of the multi-layered PVDF transducer. This corresponds to the approximation of a continuous function using discrete values. The electrode pattern of each PVDF layer is optimized by deciding the electrode of each finite element to be used or not. Genetic algorithm, suitable for discrete problems, is used as an optimization scheme. For the optimization of each layers lamination angle, the continuous lamination angle is encoded into discrete value using binary 5 bit string. For the experimental demonstration, a modal sensor for first and second modes of cantilevered composite plate is designed using two layers of PVDF films. The actuator is designed based on the criterion of minimizing the system energy in the control modes under a given initial condition. Experimental results show that the signals from residual modes are successfully reduced using the optimized multi-layered PVDF sensor. Using discrete LQG control law, the modal peaks of first and second modes are reduced in the amount of 12 dB and 4 dB, resepctively.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.3 s.309
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• pp.41-50
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• 2006

This paper presents a novel ultrasonic sensor system to overcome limited distance detection range that can be measured only more than 30cm by single ultrasonic transducer. This is accomplished by separation of receiving capacitive ultrasonic transducer from transmitting capacitive ultrasonic transducer. And hardwares and software of the system are described in detail. The system makes very close range as well as long range detect by wireless precisely. Frequency of trigger pulse is 10Hz, but it is very low frequency for transmitting data in wireless module. Therefore, for triggering between receiver and transmitter, an algorithm for mixing and distinguishing trigger pulse from carrier pulse by software is proposed. The system is designed by common microprocessor 8051. The performance of the proposed method has been assessed through two types. The first, transmitting and receiving transducer are put on both sides. And then, distance of two point is measured as far as 0mm. Secondly, transmitting transducer send out ultrasonic pulse and measure the time of flight(TOF) until a first echo from an object detected by the detached receiving transducer. The distance between the detached transducers and a reflecting object is measured as far as 7cm. Images of measured ultrasonic waves and TOF for two methods presented to prove effectiveness of results.

• Journal of Sensor Science and Technology
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• v.11 no.3
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• pp.171-182
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• 2002

The differential electromagnetic transducer for IME(implantable middle ear) system, which have two small permanent magnets glued with the same pole facing each other in the coil, has high vibration efficiency and does not influenced by external magnetic field. In this paper, using finite element method, highly efficient structure of the transducer was proposed and vibration force of the transducer was calculated by electromagnetic theory. And the necessary vibration force of transducer to transmit the sound signal to inner ear when the transducer is attached at stapes was calculated and the design parameters of the transducer were investigated. Using the parameters, the differential electromagnetic transducer was manufactured in small size to implant in confined human middle ear. And it was examined by unloaded and loaded vibration experiment using temporal bone sampled from cadaver.

• Journal of Sensor Science and Technology
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• v.15 no.4
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• pp.251-256
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• 2006

This paper describes the flexible force sensor using fiber Bragg grating (FBG) and silicone rubber for the tactile sensation to detect the distributed normal force. The newly designed FBG flexible force has simple structure and can be easily multiplexed with simple wiring compared with the other electric mechanical sensors. We designed the flexible silicone rubber transducer and found the optimum embedding position of FBG in the transducer using the finite element analysis. This flexible force sensor has good performance and is immunity to the electromagnetic field compared with any other kinds of small force sensors for tactile sensation.

• Journal of Sensor Science and Technology
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• v.16 no.4
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• pp.263-269
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• 2007

Although variable resistance displacement transducer is widely applied for its technical simplicity, electrical point contact limits measurement resolution (precision). The present study introduced roller shaped structure for electrical line contact. Proto-type transducer was developed and measurement characteristics were compared with a commercialized product. When the displacement was varied with steps of 5 mm, 1 mm, and down to 0.1 mm, the correlation coefficient between resistance and displacement decreased lower than 0.9 in the commercialized product while the proto-type transducer maintained values higher than 0.99. Therefore, the measurement resolution was enhanced by approximately 10 times. Since manufacturing also seemed easier, the present results would enable more accurate and less expensive manufacturing of variable resistance displacement transducer.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.4
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• pp.424-431
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• 2008

Recently, it is required that acoustic transducers for underwater detection and communication sensor have wide bandwidth and low operating frequency. In this research, the new acoustic transducer is proposed. This transducer is tonpilz type, and made of 1-3 piezoelectric composites as a driving parts. The developed transducer is evaluated the TVR(transmission voltage response) and RVS(receiving voltage sensitivity) characteristics around $4{\sim}14\;kHz$ frequency range and is compared to conventional tonpilz transducer made of solid piezoelectric ceramics as a driving parts. The resonance frequency of the developed transducer is decreased by 30% and the -3 dB bandwidth is increased by 90%, compared to conventional transducer with same dimensions. The value of TVR is decreased by 9 dB and The value of RVS is the same at resonance frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.983-986
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• 2007

In this paper, we addressed the IEEE 1451.x that can organize a sensor network for efficient measurement system. IEEE 1451 provides standard interface, specification and Object model for example Network Capable Application Processor(NCAP), Transducer Electronic Data Sheet(TEDS), Smart Transducer Interface Module (STIM) and so on. Especially IEEE 1451.2 defines the TEDS Formats and STIM. The TEDS makes transducer to be used independently from device. NCAP makes the component of measurement system to be handled as an object. Therefore each function block constructs system by using Add-on. IEEE 1451.x can be expend the system with Add-on and Plug-and-Play by using smart sensor and connected with current network. We expect that this method can provide the efficiency and convenience when using the measurement system.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.394-399
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• 2001

For the piezoelectric vibrator, PZT, in a general transmit-receive sensor using the ultrasonic flowmeter, the characteristics of frequency response relating to the backing materials were analyzed with the Mason equivalent circuit for design and the sensitivity of fabricated transducer relating to the matching materials was measured and discussed. The results those were measured in water for the transmit-receive characteristics of each transducer can be applied to the flowmeter sensor.

• The Journal of the Acoustical Society of Korea
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• v.31 no.8
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• pp.569-579
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• 2012

Typical Tonpilz type underwater acoustic transducers making use of piezoelectric ceramics detect the magnitude of an acoustic pressure, a scalar quantity, and convert this pressure into a proportional output voltage. The scalar sensor has no directional sensitivity. In this paper, we have proposed a new vector sensor based on the Tonpilz transducer structure, which is sensitive to both the magnitude and the azimuthal direction of an acoustic wave. Validity of this new design has been confirmed with analytic equations and finite element analyses.

• Journal of Sensor Science and Technology
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• v.30 no.1
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• pp.25-29
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• 2021

In this study, we successfully developed a highly reliable ultrasonic sediment sensor to detect the sediment levels in sewer pipes in harsh environments. The ultrasonic transducer employed in the ultrasonic sediment sensor was designed so as to possess a simple structure. The developed sensor was carefully optimized by simulating the electromechanical characteristics, radiated sound wave pressures, and directivity via finite element analysis. It was also designed to possess a simple mounting structure minimizing the flow disturbance in a 400-mm sewer pipe; additionally, eight ultrasonic transducers were arranged in a four-channel mode, allowing for measurement of the sediment height in five easy steps. Through experimental evaluations, we verified the performance of the ultrasonic sediment-level sensor and its industrial applicability. The results suggested that although the precision value was notably low at 15 mm, the sediment detection performance was adequate; therefore, the developed sensor can potentially be used in industrial applications.