• The KSFM Journal of Fluid Machinery
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• v.6 no.1 s.18
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• pp.57-65
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• 2003

The measurement uncertainties of an ultrasonic flowmeter were analyzed to evaluate its applicability to the measurement of the steam generator feedwater flow-rate in a nuclear power plant. The analyses of measurement uncertainties of a reactor power were also performed with the analyses of feedwater flow measurement uncertainties. Two ultrasonic flowmeters based on a cross-correlation technique and a transit time method were used in this study. The ultrasonic flowmeters were installed on a feedwater pipe line of a typical 1000 MWe Korea-standardized nuclear power plant to take the necessary data. The results have shown that the measurement uncertainties of the ultrasonic flowmeters are adequately smaller than those or a venturi meter. The research has also indicated that the measurement uncertainties of the reactor power based on the ultrasonic flowmeter uncertainties are sufficiently bounded by the uncertainty range usually assumed in nuclear safety analyses.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.6
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• pp.576-581
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• 2007

Ultrasonic nonlinearity has been considered as a promising method to evaluate the micro damage of material; however, its magnitude is so small that its measurement is not easy. Especially, when we use contact PZT transducer, if the contacting pressure is not kept in constant during the measurement then there exists extraneous fluctuation in the measured nonlinearity caused by the unstable contact condition, In this paper, we developed a pneumatic control system to keep the contacting pressure of transducer in constant during the measurement and analyzed the effect of contacting pressure to the ultrasonic nonlinearity measurement As a result, we found that the pressure of transducer in our measurement system should be greater than 170 kPa to measure the ultrasonic nonlinear parameter in stable with no dependency on the contacting pressure.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.2071-2078
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• 2009

In this paper, we proposed a non-contact respiration measurement system with ultrasonic proximity sensor. Ultrasonic proximity sensor approach of respiration measurement which respiration signatures and rates can be derived in real-time for long-term monitoring is presented. 240 kHz ultrasonic sensor has been applied for the proposed measurement system. The time of flight of sound wave between the transmitted signal and received signal have been used for a respiration measurement from abdominal area. Respiration rates measured with the ultrasonic proximity sensor were compared with those measured with standard techniques on 5 human subjects. Accurate measurement of respiration rate is shown from the 50 cm measurement distance. The data from the method comparison study is used to confirm the performance of the proposed measurement system. The current version of respiratory rate detection system using ultrasonic can successfully measure respiration rate. The proposed measurement method could be used for monitoring unconscious persons from a relatively close range, avoiding the need to apply electrodes or other sensors in the correct position and to wire the subject to the monitor. Monitoring respiration using ultrasonic sensor offers a promising possibility of non-contact 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 of the measurement and quality of the rate-finding for broadening the potential application areas of this technology.

• Journal of Biosystems Engineering
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• v.28 no.3
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• pp.239-244
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• 2003

The potential use of ultrasonic technique for firmness measurement of apples was evaluated. Mechanical properties(bioyield deformation, bioyield strength, rupture deformation, ultimate strength, and elastic modulus) and ultrasonic parameters (ultrasonic velocity, attenuation coefficient and the first peak frequency) of the apple flesh during the storage time were measured and analyzed. Ultrasonic parameters were determined from the measurement of ultrasonic wave transmission through the apple flesh specimen. Mechanical properties were obtained by universal testing machine. The bioyield strength, rupture strength, elastic modulus, ultrasonic velocity, and the first peak frequency of the apple flesh decreased with the storage time. The bioyield deformation, rupture deformation, and ultrasonic attenuation coefficient increased with the storage time. The correlation analysis between ultrasonic parameters and mechanical properties and the storage time was performed. The high correlations were found between the storage time and the ultrasonic parameters, and these relationships seem to be useful for determining the firmness of the apple flesh.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.8 s.197
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• pp.41-49
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• 2007

In this paper, we proposed a new ultrasonic distance measurement system with high accuracy and long range. To improve accuracy and enlarge range, the time of flight of ultrasonic is calculated by the period detecting method. In the proposed ultrasonic distance measurement system, the ultrasonic transmitter and receiver are separated but synchronized by RF(Radio frequency) module. The experiment has been implemented from short distance 1m to maximum available distance 30m. And the period detecting method is compared with the conventional threshold level method. Experimental results show the accuracy and range of the distance measurement are improved by this period detecting method.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.149-153
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• 2003

As the fastest growing flowmeter technology, multi-path ultrasonic flow-meters are gaining wider range in petroleum industry for liquid hydrocarbon custody transfer measurement. This paper describes the mult-path ultrasonic flowmeter, URO-Ex1000 the requirements necessary to prove and test in Korea & China. URO-Ex1000 haver a good results with accuracy range, but a little exceed with repeatability.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.12
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• pp.38-43
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• 2013

In this paper, the location measurement method for the reliable location data using ultrasonic sensors is proposed for the dimming control of the LED flat lamp. The measurement errors depending on the reflection angle of the object have to be considered to obtain the reliable location data in the ultrasonic sensors. In the experiment, the cause of the measurement errors depending on reflection angle is analyzed and velocity change of ultrasonic wave depending on reflection angle is measured. And the location measurement method depending on velocity change of ultrasonic wave is proposed. From the results, the average absolute deviation of the x-coordinates was 1.47cm when the location measurement method was considered, and it was closer to the true values than the average absolute deviation of the x-coordinates which was 5.89cm without regard to the reflection angle.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.2
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• pp.138-148
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• 2016

Measurement of elastic constants is crucial for engineering aspects of predicting the behavior of materials under load as well as structural health monitoring of material degradation. Ultrasonic velocity measurement for material properties has been broadly used as a nondestructive evaluation method for material characterization. In particular, pulse-echo method has been extensively utilized as it is not only simple but also effective when only one side of the inspected objects is accessible. However, the conventional technique in this approach measures longitudinal and shear waves individually to obtain their velocities. This produces a set of two data for each measurement. This paper proposes a simultaneous sensing system of longitudinal waves and shear waves for elastic constant measurement. The proposed system senses both these waves simultaneously as a single overlapped signal, which is then analyzed to calculate both the ultrasonic velocities for obtaining elastic constants. Therefore, this system requires just half the number of data to obtain elastic constants compared to the conventional individual measurement. The results of the proposed simultaneous measurement had smaller standard deviations than those in the individual measurement. These results validate that the proposed approach improves the efficiency and reliability of ultrasonic elastic constant measurement by reducing the complexity of the measurement system, its operating procedures, and the number of data.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1109-1114
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• 2003

The initial crack often occurs on the bonded interface and it is the general cause of the interface fracture. It is very significant to establish the measurement method of interfacial crack by applying the ultrasonic technology into the interface of bonded dissimilar materials. In this paper, the interfacial crack length was measured by ultrasonic attenuation coefficient in the Al/Epoxy bonded dissimilar materials of double-cantilever beam(DCB). The energy release rate, G, was obtained by the experimental and Ripling's equation measurement of compliance. The experimental results represent that the relation between interfacial crack length for the ultrasonic attenuation coefficient and energy release rate is increased proportionally. From the experimental results, a measurement method of the interfacial crack length by the ultrasonic attenuation coefficient was proposed and discussed.

• Proceedings of the Korean Nuclear Society Conference
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• 1999.05a
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• pp.124-124
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• 1999

An ultrasonic method is developed for the measurement of the two-phase mixture level in the reactor vessel or steam generator. The ultrasonic method is selected among the several non¬nuelear two-phase mixture level measurement methods through two steps of selection procedure. A commercial ultrasonic level measurement method is modified for application into the high temperature, pressure, and other conditions. The calculation method of the ultrasonic velocity is modified to consider the medium as the homogeneous mixture of air and steam. and to be applied into the high temperature and pressure conditions. The cross-correlation technique is adopted as a detection method to reduce the effects of the attenuation and the dif.JUsed reflection caused by suface fluctuation. The waveguides are developed to reduce the loss of echo and to remove the effects of obstructs. The present experimental study shows that the developed ultrasonic method measures the two-phase mixture level more accurately than the conventional methods do.