• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.97-102
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• 2011

We propose a novel displacement measurement method in the LVDT (Linear Variable Differential Transformer) structure. This proposed algorithm is independent of coil pattern, which may be implemented to PCB, or transformer component, because it is based on the signal-mapping method. we have manufactured several boards which have different coil patterns and our algorithm is ported into TMS320F2812 of TI DSP chipset. The output signal has high accuracy and high stability although PCB coil pattern are coarse.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.368-371
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• 2008

An extensometer system to measure strain and displacement of cylindrical fatigue specimen in a autoclave of high temperature and high pressure environment has been developed by KEPRI. The extensometer reads the displacement caused by fatigue loads at the target length of the specimen installed inside the autoclave. The performance of the extensometer were tested at 15MPa, $315^{\circ}C$ of a operating pressurized water reactor. Two LVDT's of magnet type were connected to the extensometer and used for converting the fatigue displacement to electronic signal. The device is being used for developing environmental fatigue curve of CF8M cast austenitic stainless steel (CASS) in the test condition of low cycle and low strain. This paper introduces the background and results of the development.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.459-465
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• 2013

This paper presents a differential interferometry technique for soil moisture change detection by measuring surface-height variation. COSMO-SkyMed SAR images were used to verify the DInSAR(differential interferometric SAR) technique. The soil penetration depth changes according to soil moisture, that causes phase change of the received signal. The height of soil surface and its displacement can be detected by a radar interferometry technique using phase difference of two received signals. To retrieve displacement variation, one of three SAR images is used as a reference image. Reference image and other two images are processed by the differential interferometry technique in the same area. The soil moisture was measured for the test sites to verify the DInSAR technique. The penetration depth is calculated by using the in-situ measured soil moisture data and it is compared with the displacement values acquired by the DInSAR technique.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1061-1068
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• 2017

A RVDT is a sensor that measures angular displacement and the output signal of RVDT is a DSBSC-AM signal. For this reason, a DSBSC-AM demodulation processor is required to determine the angular displacement from the output signal. In this paper, DADC(Digital Angle to DC) which extracts the angular displacement from the output signal of a RVDT is implemented based-on modified Costas Loop usually used in the demodulation of DSBSC-AM signal by using FPGA. DADC can used with both 4-wire and 5-wire RVDTs and can exactly compensate the phase difference between the input excitation and output signals of a RVDT unlike the conventional analog RVDT signal conditioners which require external components. Since digital signal processing technique that can enhance the linearity is exploited, DADC shows 0.035% linearity error, which is smaller than 0.005% that of a conventional analog signal conditioner. The DADC are tested in an integrated experimental environment which includes a commercial RVDT sensor, ADC and an analog output block.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.3
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• pp.160-166
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• 2016

This study proposes the development and performance evaluation of electronic proportional control valve having an LVDT. The electronic proportional control valve is composed of hydraulic valve, proportional solenoid and controller. LVDT is to reduce the steady state error for the reference input of the controller by the feedback signal to detect the displacement of the spool. Designed LVDT is applied to the common proportional valve. In order to evaluate the performance of the developed valve, the hydraulic test equipment was developed and flow tests were carried out. From experimental results, it was proved that the hysteresis was less than 1% based on the maximum flow rate.

• Journal of Drive and Control
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• v.13 no.2
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• pp.42-50
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• 2016

The conventional technique to measure the hysteresis and the null of servo valves is defined in ISO 10770-1 and based on load flow signal of the servo valve. A new technique based on the transmission line pressures is suggested in this study. The new measuring method was verified through a series of experiments. No hysteresis was observed between the spool displacement and the transmission line pressures, load pressure or each chamber pressure. Some hysteresis was observed between valve input and pressures, which was found to be the same as those of load flow and spool displacement for the valve input. By using the chamber pressures, the hysteresis and the null are easier to measure than the load pressure or differential pressure between those two chamber pressures because the chamber pressures showed sharp edges.

• Journal of Korea Multimedia Society
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• v.5 no.2
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• pp.215-221
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• 2002

In high speed optical disc devices, the vibration caused by unbalanced displacement leads the focus and tracking servo systems to be unstable, and increases the data search time. In this paper, we propose a new scheme to solve the unbalanced displacement problem. The proposed method detects the unbalanced rate by differential amplifying optical power received at photo diode and converts it into an electrical signal. controlling the speed of spindle motor, according to the detected unbalanced rate, makes it possible to improve the performance of tracking and data searching tasks. Also, we analyze the dynamic characteristics of focus and tracking servo systems in high speed mode and provide the firmware and hardware architecture that the proposed method can be installed as an add-on- module in the existing system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2283-2291
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• 2000

The neural network method is applied to automatically measure the crack opening load under random loading. The crack opening results obtained are compared with the visual measured results. Fatigue crack growth under random loading is predicted using the crack opening data measured by the neural network method, and the prediction results are compared with experimental ones. It is found that the neural network method can be successfully applied to consistently measure the crack opening load under random loading and also gives some results different from the results by visual measurement.

• Journal of Sensor Science and Technology
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• v.19 no.5
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• pp.361-368
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• 2010

ACROSS device, which is composed of an implantable microphone, a signal processor, and a vibrating transducer, is a fullyimplantable middle ear hearing device(F-IMEHD) for the recovery of patients with hearing loss. And since a microphone is implanted under skin and tissue at the temporal bones, the amplitude of the sound wave is attenuated by absorption and scattering. And the vibrating transducer attached to the ossicular chain caused also the different displacement from characteristic of the stapes. For the gain control of auditory signals, most of implantable hearing devices with the digital audio signal processor still apply to fitting rules of conventional hearing aid without regard to the effect of the implanted microphone and the vibrating transducer. So it should be taken into account the effect of the implantable microphone and the vibrating transducer to use the conventional audio fitting rule. The aim of this study was to measure gain characteristics caused by the implanted microphone and the vibrating transducer attached to the ossicle chains for the gain compensation of ACROSS device. Differential floating mass transducers (DFMT) of ACROSS device were clipped on four cadaver temporal bones. And after placing the DFMT on them, displacements of the ossicle chain with the DFMT operated by 1 $mA_{peak}$ current was measured using laser Doppler vibrometer. And the sensitivity of microphones under the sampled pig skin and the skin of 3 rat back were measured by stimulus of pure tones in frequency from 0.1 to 8.9 kHz. And we confirmed that the microphone implanted under skin showed poorer frequency response in the acoustic high-frequency band than it in the low- to mid- frequency band, and the resonant frequency of the stapes vibration was changed by attaching the DFMT on the incus, the displacement of the DFMT driven with 1 $mA_{rms}$ was higher by the amount of about 20 dB than that of cadaver's stapes driven by the sound presssure of 94 dB SPL in resonance frequency range.

• Korean Journal of Remote Sensing
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• v.34 no.1
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• pp.17-24
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• 2018

Grounding line of a glacier or ice shelf where ice bottom meets the ocean is sensitive to changes in the polar environment. Recent rapid changes of grounding lines have been observed especially in southwestern Antarctica due to global warming. In this study, ERS-1/2 and Sentinel-1A Synthetic Aperture Radar (SAR) image were interferometrically acquired in 1996 and 2015, respectively, to monitor the movement of the grounding line in the western part of Ronne Ice Shelf near the Antarctic peninsula. Double-Differential Interferometric SAR (DDInSAR) technique was applied to remove gravitational flow signal to detect grounding line from the interferometric phase due to the vertical displacement of the tide. The result showed that ERS-1/2 grounding lines are almost consistent with those from Rignot et al. (2011) which used the similar dataset, confirming the credibility of the data processing. The comparison of ERS-1/2 and Sentinle-1A DDInSAR images showed a grounding line retreat of $1.0{\pm}0.1km$ from 1996 to 2015. It is also proved that the grounding lines based on the 2004 MODIS Mosaic of Antarctica (MOA) images and digital elevation model searching for ice plain near coastal area (Scambos et al., 2017), is not accurate enough especially where there is a ice plain with no tidal motion.