• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.188-192
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• 2018

Surgery to increase cerebral blood flow is one of the treatment methods of cerebral infarction. However, invasive methods, such as surgery, may result in postoperative complications or side effects. In order to supplement this invasive method, non-invasive devices have been introduced that use human blood pressure to pressurize the extremities to increase cerebral blood flow. However, the problem of poor speed and accuracy was raised. In this paper, the perfusion index of each arm was measured by applying pressure to both arms using Blood Oxygen Level Sensor to improve the accuracy of measurement and measurement time. The pressure applied to the arm by 75% of the moment when it falls to the leg and the pressure calculated by using the pressure value obtained from the arm. Like the existing blood pressure measuring cerebral blood flow increasing device, the blood flow can be increased by more than 20% and the measurement time can be shortened, so that it can be selectively used for the patient with cerebral infarction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.8
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• pp.1083-1089
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• 2018

Surgery to increase cerebral blood flow is one of the treatment methods of cerebral infarction. In order to supplement this invasive method, non-invasive devices have been introduced that use human blood pressure to pressurize the extremities to increase cerebral blood flow. However, the problem of poor speed and accuracy was raised. In this paper, the perfusion index of each arm is measured by applying pressure to both arms using Blood Oxygen Level Sensor to improve the accuracy of measurement and measurement time. The pressure applied to the arm is calculated by using the pressure value obtained from the arm. Like the existing blood pressure measuring cerebral blood flow increasing device, the blood flow can be increased by more than 20% and the measurement time can be shortened, so that it can be selectively used for the patient with cerebral infarction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.912-921
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• 1999

Shear stress acting on the arterial wall by blood flow is an important hemodynamic factor influencing blocking of blood vessel by thickening of an arterial wall. In order to study the effects of wall elasticity on the wall shear rate distribution in an artery-divergent graft anastomosis, a rigid and a elastic model are manufactured. These models are placed in a pulsatile flow loop, which can generate the desired flow waveform. Flow visualization method using a photochromic dye is used to measure the wall shear rate distribution. The accuracy of measuring technique is verified by comparing the measured wall shear rate in the straight portion of a model with the theoretical solution. Measured wall shear rates depend on the wall elasticity and flow waveform. The mean and maximum shear rate in the elastic model are lower than those in rigid model, and the decreases are more significant near the end of a divergent tube. The reduction of mean and maximum of wall shear rate in an elastic model are up to 17 percent.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.61-67
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• 2008

In this papar, the flow meter system for pulverized coal is developed for the pulverizer-burner system of the boiler or the blast furnace. The sensor of the system a lied the capacitance with a pair of electrode on the outer wall of the electric insulator pipe. The circuit is designed for the measurement of the granule flow density combining as a measuring electrode and a reference. In order to measure granule-flow density, the calibration curve between the weight measured from loadcell and the voltage from the circuit is created. It is verified that the flow meter system has reliability and accuracy using on-line test.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2
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• pp.5-15
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• 1995

An application of the cross correlation technique by adopting ultrasonic waves for water pipe flow measuring purpose is studied. It is a non-intrusive flow metering method by determining the time of the flight of the flow turbulent noise and its non-obstructing mechanism enables to reduce process energy loss due to the flowmeter obstruction. A digital signal processor for the purpose of the real time Fourier transform was employed for the fast time calculation of the flow velocity. The overall accuracy was found as about $1\%$ for flow velocities from 0.25 m/s up to 16 m/s and for the pipe inside diameters from 50mm to 248mm. The cross correlation technique can be used for the tap water utility including most common liquid flows.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.154-160
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• 2003

Multi-path ultrasonic flowrate measuring technology is being received much attentions from a variety of industrial fields to exactly measure the flowmeter. Multi-path ultrasonic flowmeter has much advantage since it has no moving parts and not occurred pressure loss. It offers good accuracy, repeatability, linearity and Tum-down ratio can measure over 1:50. The present study investigates flowrate integration errors using weighting factors. A theoretical flow model uses power law to describe a fully developed velocity profiles and wall roughness changes. The methods of weighting factor simulate three configurations of measuring location of gaussian, chebyshev and tailor method. The obtained results show that many chord arrangements are not affected for wall roughness changes and can measure accurate flowrate.

• Journal of Korean Society of Transportation
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• v.28 no.3
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• pp.157-167
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• 2010

Density is the most important congestion indicator among the three fundamental flow variables, flow, speed and density. Measuring density in the field has two different ways, direct and indirect. Taking photos with wide views is one of direct ways, which is not widely used because of its cost and lacking of proper positions. Another direct density measuring method using two point detectors has been introduced with the concept of instantaneous density, average density and measurement interval. The relationship between accuracy and measurement interval has been investigated using the SIMULATION data produced by Paramics Application Programming Interface function. We analyze the affect of segment density accuracy by sensing gap each road condition such as sensing segment length, lane and LOS after gathering data by Paramics Application Programming Interface.

• Advances in concrete construction
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• v.13 no.5
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• pp.395-410
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• 2022

This study collected the results of material tests and full-scale pumping tests using 127 types of concrete mixtures with compressive strength ranging from 24 to 200 MPa. The results of 242 material tests showed high correlations between the viscosity of the lubricating layer and concrete, between the slump and the yield stress of concrete, between the water-binder ratio and the viscosity of lubricating layer, and between the time required to reach 500 mm of slump flow and concrete viscosity. Based on these correlations, pumpability was predicted using 101 pumping test conditions, and their accuracy was compared to the actual test results. When the rheological properties of concrete and the lubricating layer were directly measured, the prediction result showed the highest accuracy. A high accuracy can be achieved when the measured viscosity of the lubricating layer, a key determinant of concrete pumpability, is reflected in the prediction of pumpability. When measuring rheological properties is difficult, the slump test can be used to quantitatively predict the pumpability despite the lower accuracy than those of other prediction methods.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.5
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• pp.415-423
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• 2002

An experimental study using a psychrometric calorimeter was conducted to investigate the temperature and pressure mea surement errors permitted for determining cooling capacity of an air conditioner. First, the instrument calibration was made in accordance with the related test methods and guidelines in order to accurately evaluate basic performance (cooling capacity and airs flow rate). Secondly, a parametric study was performed to examine the effect of measurement error involved if temperature and pressure measuring instruments on the cooling capacity calculation. From the results, it was found that the degree of accuracy for both temperature and pressure measurements played an important role on the error occurring in the determination of cooling capacity and needed to be maintained within a certain value to guarantee required accuracy of cooling capacity.

• Journal of Biomedical Engineering Research
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• v.10 no.1
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• pp.25-32
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• 1989

In this study, Rheoencephalography( REG ) was designed and constructed. Using the cons- tructed instrument cerebral blood flow(CBF) of left and right brain, CBF change by posture, and reproducibility were studied. Followings are important results. Relative CBF could be measured noninvasively and continuously. Since reproducibility of the constructed REG was found to be quite high (4%), the accuracy of the instrument itself was proved. REG can be easily applied for testing the effect of drugs for the patients with cerebral vessel diseases since it is quite sensitive to the relative changes of CBF. Various cerebral diseases can be diagnosed by analyzing the REG waveforms. The area of restricted cerebral blood vessels can be located by arranging the electrode configuration. Comparative studies with the standard techinques of measuring CBF are needed to verify the accuracy of REG. Further studies on optimal electrode configuration and various artifacts are also necessary.