• Smart Structures and Systems
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• v.12 no.3_4
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• pp.363-379
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• 2013

Dynamic displacement of structures is an important index for in-service structural condition and behavior assessment, but accurate measurement of structural displacement for large-scale civil structures such as long-span bridges still remains as a challenging task. In this paper, a vision-based dynamic displacement measurement system with the use of digital image processing technology is developed, which is featured by its distinctive characteristics in non-contact, long-distance, and high-precision structural displacement measurement. The hardware of this system is mainly composed of a high-resolution industrial CCD (charge-coupled-device) digital camera and an extended-range zoom lens. Through continuously tracing and identifying a target on the structure, the structural displacement is derived through cross-correlation analysis between the predefined pattern and the captured digital images with the aid of a pattern matching algorithm. To validate the developed system, MTS tests of sinusoidal motions under different vibration frequencies and amplitudes and shaking table tests with different excitations (the El-Centro earthquake wave and a sinusoidal motion) are carried out. Additionally, in-situ verification experiments are performed to measure the mid-span vertical displacement of the suspension Tsing Ma Bridge in the operational condition and the cable-stayed Stonecutters Bridge during loading tests. The obtained results show that the developed system exhibits an excellent capability in real-time measurement of structural displacement and can serve as a good complement to the traditional sensors.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.58-63
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• 2010

In this paper, we proposed a wearable respiration measurement system with textile capacitive pressure sensor. Belt typed textile capacitive pressure sensor approach of respiration measurement, from which respiration signatures and rates can be derived in real-time for long-term monitoring, are presented. Belt typed textile capacitive pressure sensor has been developed for this measurement system. the distance change of two plates by the pressure of motion has been used for the respiration measurement in chest area. Respiration rates measured with the textile capacitive pressure sensor was compared with standard techniques on 8 human subjects. Accurate measurement of respiration rate with developed sensor system is shown. The data from the method comparison study is used to confirm theoretical estimates of change in capacitance by the distance change. The current version of respiratory rate detection system using textile capacitive pressure sensor can successfully measure respiration rate. It showed upper limit agreement of $3.7997{\times}10^{-7}$ RPM, and lower limit of agreement of $-3.8428{\times}10^{-7}$ RPM in Bland-Altman plot. From all subject, high correlation were shown(p<0.0001). The proposed measurement method could be used to monitor unconscious persons, avoiding the need to apply electrodes to the directly skin or other sensors in the correct position and to wire the subject to the monitor. Monitoring respiration using textile capacitive pressure sensor offers a promising possibility of convenient measurement of respiration rates. Especially, this technology offers a potentially inexpensive implementation that could extend applications to consumer home-healthcare and mobile-healthcare products. Further advances in the sensor design, system design and signal processing can increase the range and quality of the rate-finding, broadening the potential application areas of this technology.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.149-156
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• 2011

This paper reveals a distance estimation algorithm based on multi-code ultrasonic and wireless sensor network. For measuring the distances among the sensor nodes, each ultrasonic transmitter transmits multi-code ultrasonic signal simultaneously. Receivers use cross correlation method to separate the coded signals. The information of measured distances is broadcasted to each sensor node by wireless sensor network. The wireless sensor network measures the distance among the sensor nodes using the received signal strength of the broadcasting. The multi-code ultrasonic have a limitation of measurable distance. And the received signal strength is affected from an environment. This paper measures a distance using ultrasonic and a received signal strength in short range. These measured data are applied to the least square estimation algorithm. By the expansion of the fitting curve, a distance measurement in long range using the received signal strength is compensated. The coupled system reduce the error to an acceptable level.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.471-480
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• 2018

Accurate target coordinate is very important in military operations especially field artillery's ground-to-ground attack and air-force's air-to-ground attack. DOS(or TAS) is used to acquire target coordinates from long distance. DOS is comprised of LRF and goniometer. LRF measures distance between DOS and target. Goniometer is comprised of azimuth and vertical angular sensors, DMC and internal GPS receiver. DOS must set the position and orientation(finding grid north) before measurement step(target coordinate acquisition). To improve accuracy of target coordinate, VRS RTK and reference point method are proposed in DOS setup step. VRS RTK provides accurate location coordinate with small deviations, providing high accuracy and precision in positioning and orientation. As a result, horizontal coordinate(easting and northing) accuracy is improved from 2.68 mil(C.L. = 0.95) mil to 0.58 mil(C.L. = 0.95).

• Journal of Sensor Science and Technology
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• v.31 no.4
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• pp.266-270
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• 2022

Owing to the rising volume of seaborne trade, oil spills damage the marine environment for over 250 yearly. Thus, various analysis methods such as the Fourier-transform infrared (FTIR), Raman spectroscope, and gas chromatography are used to monitor oil spills at sea, but these methods are expensive. Recently, to reduce operational costs, an underwater fluorometer was adopted. However, this approach is not ideal for the remote sensing of oil spills because the device gets submerged in the sea. In this study, we have designed and developed a monitoring system that uses ultraviolet fluorescence to detect spilled oil or water from a distance, as well as proposed an analyzing method defining based on water Raman signal and QF535. Each fluorescence spectrum of water, oil (crude oil), and Bunker A was obtained using the system, and was calculated and analyzed from the spectrum individually. Based on the results of the analysis, we could successfully identity water and oil at a long distance.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.65-67
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• 2002

Resin Transfer Molding(RTM) is increasingly used for producing fiber reinforced polymer composites, the resin has to flow a long distance to impregnate the dry fibers. The measure for the resistance of the fiber preform to the resin flow is the permeability of the fiber preform. Permeability is a key issue in the design of molds and processes and in flow modeling. In this study, permeability measurement for braided preform is presented and compared with the permeability calculated numerically. Experimental techniques being used to measure the permeability are also discussed. Measurement is conducted in radial flow test under constant pressure.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.3-15
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• 2006

To determine the optimum ventilation systems during long tunnel excavation, the velocity vector profile and the contaminant's distribution at working place are studied using 2-D, 3-D numerical analysis. The main results can be summarized as follow; In case of long tunnels, blower-exhaust-mixture types which enable to use soft blast ducts is most appropriate in terms of ventilation and economical efficiency. Of the same ventilation types, ventilation efficiency has a difference according to blast ducts and the distance between fan and working place. The 3-D numerical result shows that arranging blower and exhaust ducts in the right and left corners of the tunnel respectively is effective to discharge contaminant. The result of the real measurement shows that CO concentration can be reduced to below 50 ppm, which is regulation value, as 16-minutes fan operation goes on.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1690-1698
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• 2018

Recent advances in ICT technology have transformed many of our daily lives and attracted a lot of attention to personal health. Heart beat measurement that reflects cardiac activities has been used in various fields such as exercise evaluation and psychological state evaluation for a long time, but its utilization method is limited due to its differentiation from clinical electrocardiogram. Therefore, in this study, we could observe the change of the measured signal according to the change of the distance and the position of the measuring electrodes which are non-standard electrode configuration. Based on the electric dipole model of the heart, correlation with clinical electrocardiogram could be confirmed by synthesizing multiple surface potentials measured with a shorter electrode distance than standard one. From the electromagnetic point of view, the distance between the measuring electrodes corresponds to the distance that the electric potential by the cardiac electric dipole moves, and the electric potential measured at the body surface is proportional to the moving distance of the electric potential. Therefore, it is preferable to make the distance between electrodes as long as possible, and to position the measuring electrode close to the ventricle rather than the atrium. In addition, it was found that standard electrocardiographic waveforms could be synthesized by using arithmetic sum of multiple measuring electrodes due to the relationship of electrical dipole vectors, which is obtained by dividing and positioning a plurality of measuring electrodes on a reference electrode line, such as Lead-I, Lead-II direction. Also, we obtained a significant Pearson correlation coefficient ($r=0.9113{\pm}0.0169$) as a result of synthetic experiments on four subjects.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.695-698
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• 2009

Three-dimensional (3D) shape recognition and distance recognition methods utilizing monocular camera systems have been required for field of virtual-reality, computer graphics, measurement technology and robot technology. There have been many studies regarding 3D shape and distance recognition based on geometric and optical information, and it is now possible to accurately measure the geometric information of an object at short range distances. However, these methods cannot currently be applied to long range objects. In the field of virtual-reality, all visual objects must be presented at widely varying ranges, even though some objects will be hazed over. In order to achieve distance recognition from a landscape image, we focused on the use of aerial perspective to simulate a type of depth perception and investigated the relationship between distance and color perception. The applicability of our proposed method was demonstrated in experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.484-487
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• 2000

This study is for assessing a reliability of diagnostic device through comparing diagnostic results to ACDB strength. The dielectric diagnosis using IRC (isothermal relaxation current) measurement was carried on service-aged cables. From this study, there was little correlation between dielectric diagnosis and ACBD strength in long distance cables. But the correlation between them showed in short distance below 200 m. Therefore, it is desirable to diagnose the URD cables in short distance.