• 대한기계학회논문집
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• 제18권3호
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• pp.793-804
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• 1994

Turbulence intensity caused by piston movement was almost as same tendency as the piston speed. The turbulence intensity was increased from 0.39m/s to 0.79m/s when mean piston speed increased from 2.33m/s to 4.67m/s. In this case the maximum turbulence intensity caused by piston speed was decreased about 82 percent near the top dead center at the end of compression stroke. The maximum turbulence intensity was created from 12m/s to 22m/s when inlet flow velocity was increased from 22m/s to 45m/s. Also turbulence intensity caused by inlet flow velocity was linearly increased from 0.97m/s at top dead center at the end of compression stroke. The ratio of turbulence intensity and mean inlet flow velocity was about 3 percent for inlet flow velocity.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 춘계학술대회논문집
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• pp.183-190
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• 2009

The objective of this study is to get simulation data about pulsatile flow around an interior solid body inside a bifurcated tube. All the processes were based on CFD method, with a commercial FVM code, SC/Tetra ver. 6.0 for solving, and with CATIA R16 for generating geometries. The bifurcated tube models were drawn with the bifurcated angle of 45 degrees, considering Murray's law about the diameter ratio. With various locations of the object, the effects of flow on the drag were considered. For the pulsating flow condition, the velocity wave profile was given as the inlet boundary condition. To validate all the result, the simulation was compared with the existing data of the other papers first. Overall flow field of both data were similar, but there was some difference at a zero velocity. Therefore the next simulation was continued with the sine wave profiles where there is no negative flow, and then the data was compared with one of the pulmonary artery velocity where there is negative flow. The final process was to calculate flow variables such as the wall shear stress (WSS) and to compute the drag of the solid object.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.110-112
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• 2003

A numerical simulation of an incompressible cavity flow is conducted using turbulence models. Cavity geometry and flow conditions are based on Cattafesta's experiment. Baldwin-Lomax model and ${\kappa}-{\varpi}$ model are employed. While simulation with Baldwin-Lomax model predicts the oscillatory features of the flow, the use of ${\kappa}-{\varpi}$ model in its original form makes the simulation converge to steady flow. To acquire oscillatory flow solution, Kato-Launder form and Time scale bound are adopted in production term of ${\kappa}-{\varpi}$ model. The strouhal number of the flow oscillations from the simulation results corresponds to 1 st mode in simulation but 2 nd mode in experiments. However mean velocity profile is in good agreement with the experimental data and the fluctuation profile follows the tendency of Cattafesta's results.

• Nuclear Engineering and Technology
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• 제44권7호
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• pp.735-744
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• 2012

In order to quantify the flow distribution characteristics of APR+ reactor, a test was performed on a test facility, ACOP ($\underline{A}$PR+ $\underline{C}$ore Flow & $\underline{P}$ressure Test Facility), having a length scale of 1/5 referring to the prototype plant. The major parameters are core inlet flow and outlet pressure distribution and sectional pressure drops along the major flow path inside reactor vessel. To preserve the flow characteristics of prototype plant, the test facility was designed based on a preservation of major flow path geometry. An Euler number is considered as primary dimensionless parameter, which is conserved with a 1/40.9 of Reynolds number scaling ratio. ACOP simplifies each fuel assembly into a hydraulic simulator having the same axial flow resistance and lateral cross flow characteristics. In order to supply boundary condition to estimate thermal margins of the reactor, the distribution of inlet core flow and core exit pressure were measured in each of 257 fuel assembly simulators. In total, 584 points of static pressure and differential pressures were measured with a limited number of differential pressure transmitters by developing a sequential operation system of valves. In the current study, reactor flow characteristics under the balanced four-cold leg flow conditions at each of the cold legs were quantified, which is a part of the test matrix composing the APR+ flow distribution test program. The final identification of the reactor flow distribution was obtained by ensemble averaging 15 independent test data. The details of the design of the test facility, experiment, and data analysis are included in the current paper.

• 한국멀티미디어학회논문지
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• 제21권3호
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• pp.400-414
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• 2018

It is required for today's video contents to interact with a viewer in order to provide more personalized experience to viewer(s) than before. In order to do so by providing friendly experience to a viewer from video contents' systemic perspective, understanding and analyzing the situation of the viewer have to be preferentially considered. For this purpose, it is effective to analyze the situation of a viewer by understanding the state of the viewer based on the viewer' s behavior(s) in the process of watching the video contents, and classifying the behavior(s) into the viewer's emotion and state during the flow. The term 'Flow-emotion-state' presented in this study is the state of the viewer to be assumed based on the emotions that occur subsequently in relation to the target video content in a situation which the viewer of the video content is already engaged in the viewing behavior. This Flow-emotion-state of a viewer can be expected to be utilized to identify characteristics of the viewer's Flow-situation by observing and analyzing the gesture and the facial expression that serve as the input modality of the viewer to the video content.

• 공학교육연구
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• 제15권1호
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• pp.3-8
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• 2012

This study present the standard flow chart for civil engineering considering Korean education environment. The flow charts of USA's 20 universities and Korea's 6 universities are investigated. The standard flow chart are proposed based on the standard curriculum of civil engineering and flow charts of USA and Korea though analyzing of prerequisite of each subject. The proposed standard flow chart is expected when used to improve korean universities curriculum.

• 대한기계학회논문집B
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• 제23권11호
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• pp.1390-1398
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• 1999

A numerical analysis for ROT sparger of PWR(Pressurized Water Reactor) is carried out. Computation is performed to investigate the flow characteristics as the change of design factor. As the result of this study, RDT sparger's flow resistance coefficient is K=3.53 at the present design condition if engineering mar&in is considered with 20%, and flow ratio into branch pipe is $Q_s/Q_i=0.41$. Velocity distribution at exit is not uniform because of separation in branch pipe. In the change of inlet flow rate and section area ratio of branch pipe for main pipe, flow resistance coefficient is increased as $Q_s/Q_i$ decreasing, but in the change of branch angle and outlet nozzle diameter of main pipe, flow resistance coefficient is decreased as $Q_s/Q_i$ decreasing. As the change rate of $Q_s/Q_i$ is the larger, the change rate of flow resistance coefficient is the larger. The change rate of pressure loss is the largest change as section area ratio changing. The optimal design condition of sparger is estimated as the outlet nozzle diameter ratio of main pipe is $D_s/D_i=0.333$, the section area ratio is $A_s/A_i=0.2$ and the branch angle is ${\alpha}=55^{\circ}$.

• 설비공학논문집
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• 제4권4호
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• pp.299-305
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• 1992

Saltation occurs in horizontal flow of solid and gas when the carrier gas velocity is small enough to permit enough to settling of the solid particles within the transport line. So we should examine the pneumatic flow system to lessen the unbured carbon in the power plant. In this paper the saltation velocity was studied on the various solid flow rate in the constant pipe diameter and on the various temperatures of the flow gas. The air velocity in the power plant transport lines was also surveyed in order to compare with the saltation velocity. As the solid flow rate increased in the constant diameter, saltation velocity increased and as the temperater of the flow gas inereased in the transport line, saltation velocity also increased.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.215-222
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• 1997

Flow experimental on not to be solid mortar which use Quenched Blast-furnace Slag as a fine aggregate was carried out for basic research data about fundamental study of application possibility of Quenched Blast-furnace Slag as a fine aggregate. It gives following result. The substitution rate is inversely proportional to Flow and C/S-rate same that. The relation with W/C-rate augment appear proportional : in case of C/S-rate, 1:3 increasing degree is a half of sand mortar that. Consequencely, Quenched Blast-furnace Slag motar is a counteraction to Flow in as same water content per unit. But suitable substitution rate and C/S-rate influence a little to the mortar consistency. And that reason, if C/S-rate and substitution rate will be regulated when we mix the mortar with quenched Blast-furnace Slag. that will be economic mixture.

• 유공압시스템학회논문집
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• 제5권4호
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• pp.10-16
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• 2008

In this paper, the authors benchmark a servo valve model for the fuel supply system of Auxiliary Power Unit (APU) in the KHP helicopter. This valve is directly driven with a torque motor, and the size of small gap controlled by a flapper can make change of flow rate under given pressure drop between inlet and outlet. CFD analyses using a commercial code, ANSYS-CFX 10 are performed for the series of three-dimensional models at various openness conditions. The computational results on simplified models show that CFD can play a fine roll in the design of flow path as well as in the estimation of flow force due to its precision and good repeatability. Consequently, the CFD analysis helps valve designers to understand its flow characteristics from the basis of physical fundamentals.