• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1667-1674
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• 2000

A new method is proposed to measure the flow rate in a pipe by multiple measurements of acoustic pressure using a microphone array. It is based on the realization that variation in flow velocity affects the change in wave number. The method minimizes measurement random errors and sensor mismatch errors thereby providing practically realizable flow rate measurement. One of the advantages of the method is that it does not obstruct the flow field and can provide the time-spatial mean flow rate. Numerical simulations and experiments were conducted to verify the utility of this method.

• Transactions of The Korea Fluid Power Systems Society
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• v.3 no.1
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• pp.15-19
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• 2006

In this study, a measurement method of leakage flow-rate for pneumatic driving apparatus is proposed. The existing measurement methods of leakage flow-rate of air need disassemble the test component. Therefore, there is no effective method to measure the leakage flow-rate while operating pneumatic driving apparatus. In this study, the leakage flow-rate is measure from the pressure change in an isothermal chamber that can realize isothermal conditions by stuffing steel wool into it. Therefore, wide range of flow-rate could be measured only from the pressure response and the leakage flow-rate can be measured during operating pneumatic driving apparatus. The effectiveness of the proposed method is proved by experimental results.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.2
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• pp.35-43
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• 1999

The paper describes an approach for measuring delivery flow ripple generated by oil hydraulic axial piston pumps. In order to reduce pressure ripple which cause to undesirable noise. vibration and fatigue in hydraulic systems it is indispensible measure a delivery flow ripple from pumps. Since the flow ripple measurement of flow pumps is independent of the dynamic characteristics of the connected hydraulic circuit the measurement of flow ripple is most suitable for pump fluid-borne noise rating. The measurement of flow ripple with high frequencies from axial piston pumps is made by applying the remote instantaneous flow rate measurement method which is based on the dynamic characteristics between pressure and flow rate in hydraulic pipeline. The measured flow ripple waveforms are influenced by the configuration of V-shaped triangular relief groove in the valve plate. It can be seen that the appropriate relief groove in valve plate reduces the pressure and flow ripple amplitude and frequency spectrum for high harmonics.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.98-102
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• 2007

In this study, a measurement method of leakage flow-rate for pneumatic driving apparatus is proposed. The existing measurement methods of leakage flow-rate of air need disassemble the test component. Therefore, there is no effective method to measure the leakage flow-rate while operating pneumatic driving apparatus. In this study, the leakage flow-rate is measured from the pressure change in an isothermal chamber that can realize isothermal conditions by stuffing the steel wool into it. Therefore, a wide range of flow-rate could be measured only from the pressure response and the leakage flow-rate can be measured during operating pneumatic driving apparatus. The effectiveness of the proposed method is proved by experimental results.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.411-416
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• 1999

The measurement of unsteady flow rate is of vital importance to clarify and improve the dynamic characteristics in pipeline, hydraulic components and system. There is also demand for a real time flow sensor of ability to measure unsteady flow rate with high accuracy and fast response to realize feedback control of flow rate in fluid power systems. In this paper, we propose an approach for estimating unsteady flow rate through a pipeline and components under high pressure condition. In the method, unsteady flow rate is estimated by using hydraulic pipeline dynamics and the measured pressure values at two distant points along the pipeline. The distributed parameter model of hydraulic pipeline is applied with consideration of frequency dependent viscosity friction and unsteady velocity distribution at a cross section of a pipeline. By using the self-checking functions of the method, the validity is investigated by comparison with the measured and estimated pressure waveforms at the halfway section on the pipeline. The results show good agreement between the estimated flow rate waveforms and theroetical those under unsteady laminar flow conditions. the method proposed here is useful in estimating unsteady flow rate through an arbitray cross section in hydraulic pipeline and components without installing an instantaneous flowmeter.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.10
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• pp.414-419
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• 2016

Air flow measurement is a fundamental and important task for testing, adjusting, and balancing of HVAC system. However, it is difficult to carry out in the field due to the large size and weight of the flow meter. In this study, for the purpose of developing a small and portable flow meter, we proposed a different method of static pressure measurement and verified it experimentally. In the proposed method, static pressure difference was measured by inserting a tube inside the chamber before and after the nozzles. The results were compared with measurements according to the ANSI/ASHRAE standard. The results were in good agreement, indicating that the inserted tube method could be used for static pressure measurement of a portable flow meter. The proposed method eliminates the pressure tubes that are attached outside, which results in smaller size and easy handling.

• Journal of Korean Society on Water Environment
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• v.34 no.5
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• pp.462-469
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• 2018

There are differences in method and cycle of flow rate survey depending on purpose of the operating department. To verify and use results of flow data according to the purpose, flow data of the directly measured and tele monitoring system were compared to verify validity. Flow measurement in the Ministry of Environment is aimed at setting up a standard flow of target water quality for water quality management and securing flow data of low and normal water level seasons for water quality evaluation. In this study, correlation analysis result ($R^2$) of same time zone data by direct measurement and tele monitoring system (TMS) at Seombon D point, a unit watershed of Seomjin river, for six years ('10 ~ '15) according to implementation of Total Daily Maximum Load (TDML) was wading 0.716, boating 0.962 and on bridge 0.943, and effectiveness of measurement method was verified by characteristics of flow duration as a season of dry and low-water; normal and high water are appropriate for wading, boating, and on bridge respectively. Results revealed it is reasonable to use directly measured results using the wading and boating method for low water level and dry seasons, and TMS data for rainy seasons. It can be used important data for future policy decisions.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.3
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• pp.8-13
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• 2008

The paper proposes a model-based measurement of unsteady flow rate by using distributed parameter pipeline model and the measured pressure values at two distant points along the pipeline. The distributed parameter model of hydraulic pipeline is applied with consideration of frequency dependent viscosity friction and unsteady velocity distribution at a cross section of a pipeline. By using the self-diagnostics functions of the measurement method, the validity is investigated by comparison with the measured and estimated pressure and flow rate wave forms at the halfway section on the pipeline. The results show good agreement between the estimated flow rate wave forms and theoretical those under unsteady laminar flow conditions. The method proposed here is useful in estimating unsteady flow rate through an arbitrary cross section in hydraulic pipeline and components without installing an instantaneous flowmeter.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.109-113
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• 2007

Micro-PIV is a well-known method for measurement of two- dimensional, two-component velocity in the microfluidic devices. Lots of the micro fluidic devices generate three-dimensional flow and 3D measurement of velocity is helpful to understand the physics of micro flow phenomena. In this study, we developed new micro 3D measurement method by applying 2-frame PTV in stereoscopic micro system. In this study, we did the validation study of SMPTV by using the simulated flow model to verify the accuracy and the feasibility of measurement and compared with SMPIV method. The results showed that SMPTV provides better spatial resolution and measurement accuracy than SMPIV method.

• Journal of Biosystems Engineering
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• v.23 no.5
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• pp.481-490
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• 1998

A computer vision system to measure low flow rate of solid particles was developed and tested to examine its performance with various sized 7 kinds of seeds, perilla, mung bean, paddy, small red bean, black soybean, Cuba bean and small potato tuber. The test was performed for two types of particle flow, continuous and discontinuous. For the continuous flow tested with perilla, mung bean and paddy, the tests resulted correlation coefficients for the flow rates measured by the computer vision and direct method about 0.98. Average errors of the computer vision measurement were in a range of 6∼9%. For the discontinuous flow tested with small red bean, black soybean, Cuba bean and small potato tuber, the tests resulted correlation coefficients for the flow rates measured by the computer vision and direct method 0.98∼0.99. Average errors of the computer vision measurement were in a range of 5∼10%. Performance of the computer vision system was compared with that of the conventional optical sensor to count particles in discontinuous flow. The comparison was done with black soybean, Cuba bean and small potato tuber, and resulted that the computer vision has much better performance than the optical sensor in a sense of precision of the measurement.