• Economic and Environmental Geology
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• v.30 no.5
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• pp.469-476
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• 1997

In the conventional velocity analysis, the peaks of a semblance panel are picked and the stacking velocities of the peaks are assumed as RMS velocities from which interval velocities are determined. This velocity analysis technique is correct only for horizontal homogeneous layes and incurs error in a layer whose velocity varies laterally. Tediousness of peak picking and error in velocity analysis can be reduced by automatic velocity analysis techniques. An automatic velocity analysis algorithm has been presented in order to improve these problems by considering the stacking velocity from the view point of interval velocity model and by relating the stacking velocity and the interval velocity with the traveltimes. In this paper, we apply the automatic velocity analysis method to simple models having lateral velocity anomaly to verify the effectivenesses and limits of this method. From the results of numerical experiments, we can determine the interval velocites without pickings of the stacking velocities in the one-dimensional velocity analysis and the general patterns of the laterally varying interval velocities appear in the two-dimensional case. However, the interval velocity and the depth of velocity anomaly determined by two-dimensional automatic velocity analysis are somewaht discrepant in those of the theoretical model.

• Journal of ILASS-Korea
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• v.12 no.2
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• pp.79-85
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• 2007

In this study, the effect of jet velocity profile on the thickness and velocity of the liquid sheet formed by two impinging low speed jets was investigated. To predict the distribution of thickness and velocity of liquid sheet theoretically, the jet velocity profile which was measured experimentally was adopted in addition to the constant jet velocity as well as Poiseuille's parabolic profile. For three cases, the distribution of thickness and velocity of liquid sheet was analytically predicted by solving conservation equations including stagnation point. The predicted results were compared with previous experimental results. The jet velocity profile definitely affected the resulting characteristics of liquid sheet. The distribution of thickness and velocity of liquid sheet was more close to the measured results compared with that which was predicted by the assumption of constant jet velocity.

• Journal of ILASS-Korea
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• v.5 no.1
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• pp.41-48
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• 2000

In this research, the velocity distribution of the liquid sheet formed by two impinging jets at low velocities are measured using LDV. The spatial distribution of the sheet velocity as well as the effects of impinging anlge and jet velocity on the sheet velocity are examined. The sheet velocity is highest along the sheet axis and it decreases with the increase of the azimuthal angle. With the increase of the impinging angle, the average sheet velocity is decreased due to the increased impact momentum. The average sheet velocity is proportional to the jet velocity but it is always higher than the jet velocity. This result is against the fact that the sheet velocity can be assumed to be equal to the jet velocity in the previous researches.

• Journal of Acupuncture Research
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• v.21 no.3
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• pp.83-97
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• 2004

Objective : This study was performed to evaluate the effect acupuncture on cerebral blood flow by Transcranial Doppler Ultrasonography(TCD). Methods : Monitoring of TCD was examined in stroke patients before and after acupuncture on seven points of CVA. Mean Velocity, pulsatility index, systolic velocity, diastolic velocity values are analyzed from TCD at middle cerebral artery. Results : The results showed a insignificant(p>0.05: Paired T-test) decrease in mean velocity, pulsatility index, systolic velocity, diastolic velocity, which was measured at normal middle cerebral artery. The results showed a significant($p{\leq}0.05$: Paired T-test) decrease in mean velocity, pulsatility index, systolic velocity, which was measured at injuried middle cerebral artery, except diastolic velocity. Conclusion : These results suggest that acupuncture could have a specific effect on injuried cerebral artery.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.1
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• pp.82-88
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• 2009

The output of the encoder is a digital pulse, which is also easy to be connected to a digital controller. There are various angular velocity detecting methods of M, T, and M/T. Each of them has its own properties. There is a common limitation that the angular velocity detection period is strongly dependent on the destination velocity magnitude in case of ultimate low range. They have ultimately long detection period or cannot even detect angular velocity at near zero velocity. This paper proposes a zero velocity detectable sensor algorithm with the dual encoder system. The sensor algorithm is able to keep detection period moderately at near zero velocity and even detect zero velocity within nominal period. It is useful for detecting velocity in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the algorithm validity.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.728-733
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• 2000

In this research, the velocity distribution of the liquid sheet formed by two impinging jets at low velocities are measured using LDV. The spatial distribution of the sheet velocity as well as the effects of impinging angle and jet velocity are examined. The sheet velocity is the highest along the sheet axis and it decreases with the increase of the azimuthal angle. With the increase of the impinging angle, however, the difference of sheet velocity on the liquid sheet is decreased. The average sheet velocity is proportional to the jet velocity but it is always higher than the jet velocity as against the fact that the sheet velocity can be assumed to be equal to the jet velocity in the previous researches.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.855-859
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• 2007

It is essential to obtain accurate and highly reliable streamflow data for water resources planning, evaluation and management as well as design of hydraulic structures. A new discharge estimation method, which is named 'non-dimensional velocity distribution and index-velocity method,' was proposed in this research. This method showed very close channel discharges which were calculated with the exiting velocity-area method. When velocity-area method is used to estimate channel discharge, it is required to observe point velocities at every desired point and vertical using a current meter like Price-AA. However 'non-dimensional velocity distribution and index-velocity method' is used, it become optional to observe point velocities at every desired point and vertical. But this method can not be applied for the cases of very complex and strongly asymmetric channel cross-sections because non-dimensional velocity distribution by entropy concept may be quite biased from that of natural rivers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3C
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• pp.295-301
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• 2010

In this paper, we propose a new mouthpiece model for the electronic wind instrument using a propeller and linear analysis for fast tracking wind velocity blown. This method is a modification of the velocity anemometer for fast tracking wind velocity by the propeller's angular velocity (speed of revolution). In the case of velocity anemometer, wind velocity is calculated using the property that wind velocity is in proportion to the propeller's angular velocity. However, wind velocity and angular velocity of the propeller are not in one-one correspondence because wind velocity takes some transitional time for the expected wind velocity to be calculated from angular velocity. To resolve this problem, we propose a method for finding the impulse response of the system which can be considered as a linear system, and for estimating the wind velocity by deconvolving the propeller's angular velocity with the impulse response. To experiment and to prove the validity of the proposed system, we designed a mouthpiece model which consists of a motor, a propeller and an encoder. The result of estimated wind velocity in this method showed that this system is about eightfold faster than the method by the conventional velocity anemometer.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.1
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• pp.85-91
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• 2017

To develop a pressurized chemical looping combustor, effect of pressure on minimum fluidization velocity and transition velocity to fast fluidization was investigated in a two-interconnected pressurized fluidized bed system using oxygen carrier particle. The minimum fluidization velocity was measured by bed pressure drop measurement with variation of gas velocity. The measured minimum fluidization velocity decreased as the pressure increased. The transition velocity to fast fluidization was measured by emptying time method and decreased as the pressure increased. Gas velocity in the fuel reactor should be greater than the minimum fluidization velocity and gas velocity in the air reactor should be greater than the transition velocity to fast fluidization to ensure proper operation of two interconnected fluidized bed system.

• Proceedings of the KSRS Conference
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• v.2
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• pp.672-675
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• 2006

The geostrophic current component is estimated from the sea surface velocity observed by the long-range High-Frequency Ocean Radar (HF radar) system in the upstream of the Kuroshio, by comparing with geostrophic velocity determined from along-track T/P and Jason-1 altimetry data. However, the sea surface velocity of the HF radar (HF velocity) contains not only the geostrophic current but also the ageostrophic current such as tidal current and wind-driven Ekman current. Tidal current component is first extracted by the harmonic analysis of the time series of the HF velocity. Then, the Ekman current is further estimated from daily wind data of IFREMER by applying the least-square method to the residual difference between the HF velocity and the altimetry geostrophic velocity. As a result, the Ekman current in the HF velocity is estimated as 1.32 % of the wind speed and as rotated 45$^{\circ}$ clockwise to the wind direction. These parameters are found almost common in the Kuroshio area and in the Open Ocean. After these corrections, the geostrophic velocity component in the HF velocity agrees well with the altimetry geostrophic velocity.