• Magazine of the Korean Society of Agricultural Engineers
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• v.14 no.1
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• pp.2557-2569
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• 1972

Hydraulic computations to determine the elevation of canal bottom and mater surface for box type concrete culverts are discussed. Velocity and cross sectional area of flow are computed from Manning's formula. Aad then head loss and velocity head are considered to determine the elevation of bottom and water surface. For stress analysis, 13.5 ton live load and earth pressure are considered. Also longitudinal stress of box culverts is checked.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.7
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• pp.924-929
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• 2000

This paper addresses a new technique of measuring the mean flow velocity over the cross sectional area of the pipe using sound field reconstruction. When fluid flows in the pipe and two plane waves propagate oppositely through the medium, the flow velocity causes the change of wave number of the plane waves. The wave number of the positive going plane wave decreases and that of negative going one increases in comparison to static medium in the pipe. Theoretical backgrounds of this method are introduced in detail and the measurement of mean flow velocity using the sound field reconstruction is not affected by velocity profile upstream of microphones.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.243-246
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• 2000

This paper addresses a new technique of measuring the mean flow velocity not only over the cross sectional area but also along the pipe by exploiting the acoustic plane waves in the pipe. When fluid flows in the pipe and two plane waves propagate oppositely through the medium in it, the flow velocity causes a change of the wave number of the plane waves. The wave number of the positive going plane wave decreases but oppositely that of negative going one increases in comparison to no flow of the medium in the pipe. Theoretical backgrounds of this method are in details discussed and measurement results of the mean flow velocity are illustrated to reveal the feasibility and effectiveness of the suggested technique.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.49-59
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• 2008

The effects of design parameters on the pellet transport rate in the ejector system which is widely used in the production processes of automotive parts were investigated experimentally. The primary nozzle geometry, the area ratio (R) of nozzle exit cross-sectional area to mixing chamber cross-sectional area and the distance (S) from primary nozzle exit to mixing chamber entrance were considered as the design parameters. The area ratios of the primary nozzle were varied from R=0.10 to R=0.25, 0.30, 0.40 and 0.55. The primary nozzle was positioned at the non-dimensional distance (S/D) of 1.30, 1.87, 2.44, 3.00 and 3.75, normalized using the mixing chamber diameter (D). The design parameters were determined to run with high efficiency by measuring the pellets transport rate. The geometry and the area ratio (R) of the primary nozzle had an effect on the pellet transport rate of the ejector system, and the area ratio of R=0.3 was carefully selected after taking the minimum fluidization velocity and transport rate of applied pellets into account. The higher pellet transport rate with the variation of the distance (S/D) was observed at S/D of 2.44.

• Journal of Korean Society of Forest Science
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• v.113 no.3
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• pp.339-348
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• 2024

Debris flow is a typical type of mountainous sediment disaster that can cause widespread damage to both lives and property, making it essential to understand its behavioral characteristics for effective prevention. In this study, pre- and post-event Light Detection And Ranging(LiDAR) data from the Dosan-ri area in Bonghyeon-myeon, Yeongju-si, Gyeongsangbuk-do, Republic of Korea where debris flows occurred in 2023, were used to calculate the actual affected area and terrain change volume caused by the debris flow. These calculated values were then compared with those derived from the numeric simulation model, Morpho2DH, based on field surveys and laboratory investigation data. Additionally, the model's applicability was assessed by conducting cross-sectional elevation analyses based on the extent of the affected area and comparisons of the results. The findings indicate that the debris flow affected area and terrain change volume estimated by the Morpho2DH model were approximately 152% and 178% higher, respectively, compared to the LiDAR-based results. Pearson correlation analysis of the cross-sectional elevation changes showed a positive correlation, with Pearson Correlation Coefficients(PCC) of at least 0.65

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3056-3061
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• 2007

The technology of AC solenoid valves is now considered as a core technology in the fields of the production line of semi-conductor chips and the micro fluid chips for medical applications. And AC solenoid valves, which operate by compressed air, are characterized by high speed response, great repeatability and that the pressure on the cross sectional area of poppet is kept constant regardless of the fluctuation of the pressure exerted on the ports. In this study, AC solenoid valves that posses the high-speed responsibility and the high rate of flow have designed and analyzed through the law of equivalent magnetic circuit and Finite Element Method (FEM) respectively. In case of poppet, Flow field characteristic was analyzed by the variation of poppet and it was able to display flow field by changing the location of the poppet. Also, we verified possibility of the design through the static and dynamic pressure and the 3D distribution curve of the force by working the front poppet.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.169.2-169.2
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• 2010

Recently, the massive offshore bridges in a ship passage have been constructed on the sea. Therefore, the ship impact protection for the bridge-piers are installed to consider the possibility of vessel collision danger. Due to the ship impact protection, the flow-field characteristics are changed in comparison with the condition without the ship impact protection. Especially, the fluid velocity between the pier and the ship impact protection is possible to increase due to the contraction of the cross sectional area of flow. In this study, the tidal energy magnitude around the ship impact protection of Incheon bridge is assessed by simulating the flow-field by using FLOW-3D software.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.04a
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• pp.235-244
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• 1997

The empirical factor and reaction force based on published data were involved to investigate compressible flows through sudden enlargement and sudden contraction passages. Analytical solutions of engineering interest were obtained from one-dimensional steady compressible gas dynamic equations. The effects of compressibility, cross-sectional area ratio, and inlet Mach number on the air flows were discussed with regards to the total pressure loss and flow choking. The present results provide available information necessary ta design the compressible pipe flow systems.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.345-348
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• 2006

In sheet metal forming process using press and draw die some defect can be made because of the high pressure of air pocket between draw die and the product. The purpose of this study is to develop a program to decide an optimal combination of air vent hole size and number to prevent those defect on product. The air inside air pocket is considered as ideal gas and the compression and expansion is assumed as isentropic process. The mass flow is computed in two flow condition: unchocked and chocked condition. The present computation obtains required cross-sectional area of air vent hole for not exceeding the user specified pressure such as the pressure for yielding strength of the product or the pressure for unchocked flow. To validate the program the present results are compared with the results of other researchers and commercial CFD code.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.44-47
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• 2004

Vortexing might occur during draining from tanks which reduces the rate of outflow. This phenomenon has practical relevance in the fuel feed system in space vehicles and rockets. Due to environmental disturbances rotational motion can be generated in the liquid-propellant tank, which in turn can affect the rate of outflow to the engines. The phenomenon is initialized by rotating the fluid In the experimental tank. The dip quickly develops into a vortex with an air core, which extends to the bottom port, reducing the effective cross-sectional area of the drain outlet and consequently the flow rate. Flow characteristics are investigated using SPIV(Stereoscopic Particle Image Velocimetry) method.