• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.450-456
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• 2010

This study was conducted in order to design a piston, part of a shock absorber, and the findings after examining the features of the velocity distribution and the static pressure distribution of oil on a low-velocity piston are as follow. The compression speed of oil passing through an 0.9 mm orifice was 0.0156~0.0642 m/s, and the velocity vector of the velocity distribution and the static pressure distribution had a greater tendency to rotate when the velocity increased. In case of the velocity vector of the velocity distribution and the static pressure distribution with an 0.8mm orifice, the speed changed secondarily, the second pressure-drop was observed and as for the distribution of the streamline around the orifice, a vortex was produced around the center. As for the velocity distribution of oil passing from the compression cylinder to the compact pipe, the velocity was greater in orifice of small diameter. Also, the greater the pressure difference was between the compression cylinder and the compact cylinder, the greater the force it was upon the piston.

• 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.

• Journal of Environmental Science International
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• v.28 no.6
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• pp.535-544
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• 2019

We computed parameters that affect velocity distribution by applying Chiu's two-dimensional velocity distribution equation based on the theory of entropy probability and acoustic doppler current profiler (ADCP) of Jungmun-stream, Akgeun-stream, and Yeonoe-stream among the nine streams in Jeju Province between July 2011 and June 2015. In addition, velocity and flow were calculated using a surface image velocimeter to evaluate the parameters estimated in the velocity observation section of the streams. The mean error rate of flow based on ADCP velocity data was 16.01% with flow calculated using the conventional depth-averaged velocity conversion factor (0.85), 6.02% with flow calculated using the surface velocity and mean velocity regression factor, and 4.58% with flow calculated using Chiu's two-dimensional velocity distribution equation. If surface velocity by a non-contact velocimeter is calculated as mean velocity, the error rate increases for large streams in the inland areas of Korea. Therefore, flow can be calculated precisely by utilizing the velocity distribution equation that accounts for stream flow characteristics and velocity distribution, instead of the conventional depth-averaged conversion factor (0.85).

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.441-450
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• 2004

The velocity distribution of gas molecules from the experimental results was confirmed as the same with the Maxwell-Boltzmann's theoretical results within the experimental error. This study is on the realization of the Maxwell-Boltzmann's velocity distribution of gas molecules by the molecular dynamics(MD) method. The Maxwell-Boltzmann's velocity distribution of gas molecules is extremely important to confirm the equilibrium state because the properties of a thermodynamic system shall be obtained from the system's equilibrium configuration in the MD method. This study is the first trial in the successive researches to calculate the properties of a thermodynamic system by the computer simulations. We confirmed that the maxwell-boltzmann's velocity distribution is developed in some transient time after starting a simulation and dependent on the size of a system. Also it is found that the velocity distribution has no relation with an initial configuration of gas molecules.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1560-1565
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• 2007

In this study, Chiu's velocity distribution equation recently developed from the probability and entropy concepts is used to establish a linkage between the mean velocity obtained from the Manning's equation and the corresponding velocity distribution in a channel cross section. The linkage to be established enables computing the velocity distribution along with the mean velocity, from simple hydraulic data such as Manning's n, hydraulic radius and channel slope irrespective of including sediment or not.

• 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 the Korean Society for Railway
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• v.10 no.3 s.40
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• pp.343-349
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• 2007

The flow velocity distribution at inlet and exit of a DPF was measured using a Pitot tube and 2-D positioning equipment. An adaptor which was designed for accessing the Pitot tube probe into inlet of the DPF was fabricated with inlet flange of the DPF. The Pitot tube which was mounted in the 2-D positioning machine could access to the inlet of the DPF through the rectangular window of the adaptor. Automation of the velocity measurement at the inlet and exit of the DPF was effectively achieved and measuring time was reduced drastically. The flow velocity distribution at the inlet of the DPF showed parabola shape with maximum velocity near to the center of the DPF, as expected. The velocity distribution at the exit of the DPF showed crown shape, that is, the flow velocity distribution near to the center of the DPF is lower than that at surrounded peripheral region of the DPF.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.93-100
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• 2007

The flow velocity distribution at inlet and exit of Diesel Particulate Filter(DPF) by fabricating L-shape connector with the DPF was measured using a Pitot-tube and 2-D transverse machine. An adaptor designed for making the Pitot tube probe access to the inlet and exit of the DPF was connected with the inlet and exit flange of the DPF, respectively. The Pitot tube which was mounted in the 2-D positioning machine could access to the inlet and exit of the DPF through the rectangular window of the adaptor. The L-shape connector in the DPF inlet has a flow guide which is a perforated steel pipe. The flow velocity distribution at the inlet of the DPF showed a chaotic velocity distribution which is different from that with a diffuser type connector. The velocity distribution at the exit of the DPF showed a crown shape which is similar to that of the diffuser type connector. The velocity distribution at the exit of DPF showed different patterns according to the air flow rate.

• 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.