• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.14-22
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• 1997

The position of propeller fan from duct inlet is one of basic parameters for the design of propeller fan. To investigate the effect of its position on fan characteristics, the inlet flow fields and relative flow angles were measured by a 5-hole pitot tube. The experimental results indicate that the ratio of radial flow introduced from propeller circumference to total inlet flow increases with the increase of propeller distance from duct inlet. When fan operates without duct, the total flow rate and the radial flow ratio are higher than those of any other positions of propeller relative to duct inlet. The radial flow ratio decreases as a flow coefficient and the propeller distance decrease. Therefore the front flow fields can be adjusted in some extent by varying the propeller distance according to a fan loading. The inlet flow angles are decreasing a little as a rotational speed and the propeller distance decrease. In the present case it was judged that the deviation angle of outlet flow became negative owing to a flow separation near a trailing edge.

• Journal of Industrial Convergence
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• v.21 no.9
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• pp.1-9
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• 2023

The purpose of this study is to verify the mediating effect of Learning Flow in the relationship between Growth Mindset and Career Adaptability. Based on 203 response data collected from university students, hypotheses were analyzed using SPSS 26.0 and AMOS 26.0 programs. According to the result of this study, Growth Mindset had a direct positive (+) effect on Learning Flow (𝛽=.403, p<.001), and Learning Flow also had a positive (+) effect on Career Adaptability (𝛽=.393, p<.001). Also, in the relationship between Growth Mindset and Career Adaptability, Learning Flow showed a mediating effect. This means that in order for Growth Mindset to affect Career Adaptability, Learning Flow must be considered as essential. To this end, it suggests that it is important to build a Learning Flow along with cultivating a Growth Mindset.

• Journal of Ocean Engineering and Technology
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• v.23 no.2
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• pp.18-27
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• 2009

This study was conducted to examine the effect of wind on the circulation of seawater in Gamak Bay, which contains numerous farms for fish and shellfish but suffers a significant loss by fisheries nearly annually from harmful algal blooms. In numerical experiments with a simplified bathymetry for Gamak Bay, the wind in summer appeared to more strongly influence the east-westward flow than the south-northward flow. In winter, this trend was nearly similar to the summer but seemed to have a greater effect on the flow at the north-west of the bay than the flow at the south mouth of the bay. On the other hand, in numerical experiments with a realistic bathymetry for Gamak Bay, the wind in summer appeared to more strongly influence the east-westward flow than the south-northward flow. Furthermore, the effect of the wind was stronger at the south mouth of the bay than at the north-west of the bay. In contrast, the wind in winter affected the east-westward flow more strongly and its effect appeared stronger at the north-west of the bay than at the south mouth of the bay. In addition, the effect of the wind tended to increase with distance from the east to the west. Therefore, the tidal currents in Gamak Bay proved to be strongly influenced by the wind, in particular east-westward. However, some measures are urgently required to improve the water quality of the bay, since the south-northward flow turned out to be obstructed by an east-westward shoal located in the middle of the bay.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.4
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• pp.411-417
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• 2009

The thermo-flow field in road tunnel is influenced by some facts such as piston effect of vehicle's move, operation of ventilation facilities, natural wind and buoyancy effect of fire plume. Among those, piston effect is one of primary causes for formation of air flow in road tunnel and has an effect on initial direction of smoke flow in tunnel fire. In this study to analyze the unsteady flow in the tunnel caused by the run of vehicle, the experimental study of vehicle-induced unsteady flow on a reduced-scale model tunnel is presented. While the three types of vehicle shape such as basic type of rectangular shape, diamond-head type and stair-tail type are changed, the pressure and air velocity variations with time are measured. The rising ratio of pressure and velocity are in order of "basic type of rectangular shape > stair-tail type > diamond-head type". The experimental results would be good data for development of a numerical method on the vehicle-induced unsteady tunnel flow.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.3
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• pp.293-299
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• 2015

We analyzed the damage effect on Glass Fibre Reinforced Plastics(GFRP) under air flow by irradiation of continuous wave near-IR laser. Damage process and temporal temperature distribution were demonstrated and material characteristics were observed with laser intensity, surface flow speed and angle. Surface temperature on GFRP rapidly increased with laser intensity, and the damaged pattern was different with flow characteristics. In case of no flow, penetration on GFRP by burning and flame generation after laser irradiation was appeared at once. GFRP was penetrated by the heat generated from resin ignition. In case of laser irradiation under flow, a flame generated after burning extinguished at once by flow and penetration pattern on GFRP were differently shown with flow angle. From the results, we presented the damage process and its mechanism.

• The Journal of Korean Medicine
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• v.31 no.4
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• pp.178-186
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• 2010

Objectives: This study was to investigate the effect of moxibustion on peripheral blood flow by Doppler ultrasound in post-stroke hemiplegia patients. Methods: Moxibustion was applied on the points of LI4, TE3, TE5 and LI11 on the affected side, and blood flow of the radial artery was measured using the Minimax-Doppler-K device. Blood flow velocity and pulsation index were analyzed before, during, and after moxibustion. Results: The mean value of blood flow velocity in 13 patients showed a tendency of increase during moxibustion, but there was no significant difference in blood flow velocity before and after moxibustion, or pulsation index during and after moxibustion. In addition, among the five patients who showed marked increase tendency on the blood velocity graph, there was significant increase in blood velocity during, and after moxibustion compared with before moxibustion. Conclusions: This study suggests that moxibustion has an effect on peripheral blood flow in stroke patients with hemiplegia. Further validity tests with a larger scale sample are needed for the evidence of its practical use.

• Wind and Structures
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• v.12 no.6
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• pp.541-551
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• 2009

This paper explains how to correctly measure the drag coefficient of a circular cylinder in wind tunnels with large blockage ratios and for the sub-critical to the super-critical flow regimes. When dealing with large blockage ratios, the drag has to be corrected for wall constraints. Different formulations for correcting blockage effect are compared for each flow regime based on drag measurements of smooth circular cylinders performed in a wind tunnel for three different blockage ratios. None of the correction model known in the literature is valid for all the flow regimes. To optimize the correction and reduce the scatter of the results, different correction models should be combined depending on the flow regime. In the sub-critical regime, the best results are obtained using Allen and Vincenti's formula or Maskell's theory with ${\varepsilon}$=0.96. In the super-critical regime, one should prefer using Glauert's formula with G=0.6 or the model of Modi and El-Sherbiny. The change in the formulations appears at the flow transition with a variation of the wake pattern when passing from sub-critical to super-critical flow regimes. This parameter being not considered in the known blockage corrections, these theories are not valid for all the flow regimes.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.2
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• pp.177-184
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• 2013

This study analyzed the hydraulic characteristics of a venturi flume with a circular cone using a 3-D numerical model which uses RANS(Reynolds-Averaged Navier-Stokes Equation) as the governing equation. The venturi flume with the circular cone efficiently measures the discharge in the low-flow to high-flow range and offers the advantage of accurate discharge measurements in the case of a low flow. With no influence of the tail-water depth, the stage-discharge relationship and the flow behaviors were analyzed to verify the numerical simulation results. Additionally, this study reviewed the effect of the tail-water depth on the flow. The stage-discharge relationship resulting from a numerical simulation in the absence of an effect by the tail-water depth showed a maximum margin of error of 4 % in comparison to the result of a hydraulic experiment. The simulation results reproduced the overall flow behaviors observed in the hydraulic experiment well. The flow starts to become influenced by the tail-water depth when the ratio of the tail-water depth to the total head exceeds approximately 0.7. As the ratio increases, the effect on the flow tends to grow dramatically. As shown in this study, a numerical simulation is effective for identifying the stage-discharge relationship of a venturi flume with various types of venturi bodies, including a venturi flume with a circular cone.

• Nuclear Engineering and Technology
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• v.31 no.6
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• pp.618-630
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• 1999

An analytical model that includes the steam condensation effect has been derived and a parametric study has been performed. In addition, a series of experiments were performed and a total of 34 experimental data for the onset of CCFL in nearly horizontal countercurrent two-phase How have been obtained for various flow rates of water. Comparisons of the present CCFL data with slug formation models show that the agreement between the present as well as the existing model and the data is about the same. However, the deviation between the Taitel and Dukler's model predictions and the data is the largest when if j$_{f}$<0.04 m/s. A parametric study of the effect of the steam condensation using the present model shows that, when all local conditions are similar, the model predicted local gas velocities that cause the onset of flooding are slightly lower when condensation occurred. Based on the visual observation and the evaluation of the present work, it has been concluded that the criterion derived for the onset of slug flow can be directly used to predict the onset of inner flooding in nearly horizontal two-phase flow within the experimental ranges of the present work.

• Wind and Structures
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• v.18 no.1
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• pp.69-82
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• 2014

Flow around a small white fir tree was investigated with varying the length of the bottom trunk (hereafter referred to as bottom gap). The velocity fields around the tree, which was placed in a closed-type wind tunnel test section, were quantitatively measured using particle image velocimetry (PIV) technique. Three different flow regions are observed behind the tree due to the bottom gap effect. Each flow region exhibits a different flow structure as a function of the bottom gap ratio. Depending on the gap ratio, the aerodynamic porosity of the tree changes and the different turbulence structure is induced. As the gap ratio increases, the maximum turbulence intensity is increased as well. However, the location of the local maximum turbulence intensity is nearly invariant. These changes in the flow and turbulence structures around a tree due to the bottom gap variation significantly affect the shelter effect of the tree. The wind-speed reduction is increased and the height of the maximum wind-speed reduction is decreased, as the gap ratio decreases.