• Journal of the Korean Society for Precision Engineering
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• v.10 no.1
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• pp.28-33
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• 1993

Measurements errors due to sound velocity effect on vibrating gas densimeters were described. Nitrogen was used to calibrate the densimeter, and oxygen was employed to determine a coefficient for the compensation of sound velocity effect. Sound velocity effects were shown with methane at temperatures of 7.97, 19.93 and 39.57 .deg. C, and pressures up to 3.6 Mpa. A relative error of about 1% was introduced when the nitrogen calibrated densimeter was used to measure densities of pure methane. A method of sound velocity effect compensation was able to reduce the error down to 0.1%.

• 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.

• Journal of the Korea Concrete Institute
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• v.11 no.3
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• pp.161-170
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• 1999

The KLCC Petronas Tower 2, one of the world tallest twin reinforced concrete towers constructed in Kuala Lumpur, Malysia, was instrumented during construction for the measurement of vertical time-dependent deformation of columns and corewall. Field measurements were made by means of vibrating wire strain gauges at the corewall, tower and bustle perimeter columns at selected floor levels of the building. Parallel to this observation, laboratory tests were performed on concrete cylinders made in the field in order to obtain the variations of concrete compressive strengths, elastic moduli, strains of creep and shrinkage with time. Monitored vertical deformations are in a good agreement with the prediction based on actual construction sequence and concrete properties from laboratory tests, as well as the analytical results reflected in actual column compensation of the building.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.182-190
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• 2004

This paper presents reconstruction analysis of vehicle trajectory using records of a developed black box, and results of validation tests. For reconstruction of vehicle trajectory, the black box records the longitudinal and lateral accelerations and yaw-rate of vehicle during a pre-defined time period before and after the accident. One 2-axis accelerometer is used for measuring accelerations, and one vibrating structure type gyroscope is used for measuring yaw-rate of vehicle. The vehicle's planar trajectory can be reconstructed by integrating twice accelerations along longitudinal and lateral directions with yaw-rate values. However, there may be many kinds of errors in sensor measurements. The causes of errors are as follows: mis-alignment, low frequency offset drift, high frequency noise, and projecting 3-dimensional motion into 2-dimensional motion. Therefore, some procedures are taken for error compensation. In order to evaluate the reliability and the accuracy of trajectory reconstruction results, the black box was mounted on a passenger car. The vehicle was driven and tested along various specified lanes. Through the tests, the accuracy and usefulness of the reconstruction analysis have been validated.

• Smart Structures and Systems
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• v.6 no.2
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• pp.167-182
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• 2010

An adaptronic strut for machine tools with parallel kinematics for compensation of the influence of geometric errors is introduced. Implemented within the strut is a piezoelectric sensor-actuator unit separated in function. In the first part of this contribution, the functional principle of the strut is presented. For use of one piezoelectric transducer as both, sensor and actuator as so-called self-sensing actuator, the acquisition of the sensing signal while actuating simultaneously using electrical bridge circuits as well as filter properties are examined. In the second part the control concept developed for the adaptronic strut is presented. A co-simulation model of the strut for simulating the controlled multi-body behavior of the strut is set-up. The control design for the strut as a stand-alone system is tested under various external loads. Finally, the strut is implemented into a model of the complete machine tool and the influence of the controlled strut onto the behavior of the machine tool is examined.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.3
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• pp.250-257
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• 2001

SRM drives generate large vibration and acoustic noise because it is rotated by step pulse mmf and switching commutation mechanism. The main vibration source of SRM drive is generated by rapidly variation of radial force when phase winding current is extinguished for commutation action. So the rapidly variation of radial force is repressed firstly to reduce vibrating force of SRM drive. This paper suggests an SRM excitation scheme using unidirect-short compensation winding to reduce vibration of the motor. The motor is excited by a two stage commutation method during commutation period. This paper suggests an SRM excitation scheme using unidirect-short compensation winding to reduce vibration of the motor. The motor is excited by a tow stage commutation method during commutation period. This reduction effect of vibration is verified with the result obtained in the test of prototype machine.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1218-1223
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• 2007

A surface micro machined angular rate sensor utilizing a vibrating MEMS structure on a silicon has been developed. These tuning fork angular rate sensors are extremely rugged, inherently balanced, and easy to fabricate. The device is fabricated using a temperature compensation method based on automatic gain control technique. A linearity of approximately 0.6%, limited by the on-chip electronics has been obtained with this new sensor. Tests of the sensor demonstrate that its performance is equivalent to that required for implementation of a yaw control system. Vehicle handling and safety are substantially improved using the sensor to implement yaw control.

• Journal of the Korean Society of Visualization
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• v.17 no.3
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• pp.66-69
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• 2019

An image compensating algorithm with high-vibration movement is proposed, using optical flow and the Kalman Filter. The temporal motion vector field is calculated by Optical flow and suspicious vectors are removed or adjusted by the Gaussian interpolation method. The high-vibrated vector filled is stabilized by the Kalman filter. Lastly, compensated images are obtained by affine transformation. This proposed algorithm gives good compensated video images on high-vibration situations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.397-402
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• 2003

The FM demodulation method for a bulk homodyne laser interferometer is presented. The Doppler frequency that represents the surface velocity of a vibrating object is obtained by using the bulk homodyne laser interferometer, and converted to the voltage signal by using the proposed analogue FM demodulation circuit. The DC offsets of the interferent signals that are obtained from the bulk homodyne interferometer are eliminated by using a simple subtraction. The new method for compensation of the asymmetry of each channels is presented. The light power variation of the interferometer is normalized by using the Auto Gain Controller(AGC). The proposed FM demodulation algorithm is proved by the theoretical method, and validated by the experimental results. In experiments, the proposed FM demodulation algorithm is compared with the conventional demodulation methods.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.55-57
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• 1999

SRM Drives generate large vibration and acoustic noise because it is rotated by step pulse mmf and switching commutation mechanism. The main vibration source of SRM Drive is generated by rapidly variation of radial force when phase winding current is extinguished for commutation action. So the rapidly variation of radial force is repressed firstly to reduce vibrating force of SRM Drive. This paper suggests the vibration reduction method that SRM Drive with unidirect-short compensation winding is excited by a two stage commutation method at commutation period. This reduction effect of vibration is verified with the result obtained in the test of prototype machine.