• Journal of the Korean Society of Visualization
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• v.17 no.1
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• pp.19-25
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• 2019

We report a study on the dynamics of the transport of a capsule immersed in a vertical pipe. Techniques to convey objects through liquid flow pipes using a hydraulic mean are used to transport sludge and hazardous materials. For the better understanding of the techniques, we developed a theoretical model to predict the transport speed of a cylindrical capsule in a vertical pipe. The comparison of the model prediction with the experiments shows that our model using the lubrication approximation precisely describes the experimental observations in cases where the gap between the capsule and pipe wall is sufficiently small. Our study suggests parameters to control the falling speed and thus enable an accurate control of the capsule speed in hydraulic transport systems.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.13-20
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• 2012

In this paper, we present the result of an investigation pertaining to the pipe stiffness of buried flexible pipes. Pipe stiffness (PS) formula for the parallel plate loading condition is derived based on the elasticity theory. Vertical and horizontal displacements are also derived. Vertical deflection is always larger than the horizontal deflection because some of energy due to overburden load is stored in the pipe but the difference is negligibly small. In the study, mechanical properties of the flexible pipes produced in the domestic manufacturer are tested and the results are reported in this paper. In addition, pipe stiffness is determined by the parallel plate loading tests and the finite element analysis. The difference between test and analysis is less than 14% although there are significant variations in the mechanical properties of the pipe material. Therefore, it was found that the finite element analysis can be used to predict the pipe stiffness instead of conducting parallel plate loading test.

• Journal of the Korean Society for Advanced Composite Structures
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• v.4 no.3
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• pp.38-44
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• 2013

Glass fiber reinforced plastic (GRP) pipes buried underground are attractive for use in harsh environments, such as for the collection and transmission of liquids which are abrasive and/or corrosive. In this paper, we present the result of investigation pertaining to the structural behavior of GRP flexible pipes buried underground. In the investigation of structural behavior such as a ring deflection, experimental and analytical studies are conducted. In addition, vertical ring deflection is measured by the field test and finite element analysis (FEA) is also conducted to simulate behavior of GRP pipe buried underground. Based on the results from the finite element analyses considering soil-pipe interaction the vertical ring deflection behavior of buried GRP pipe is predicted. In addition, analytical and experimental results are compared and discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.481-489
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• 2010

Experiments on laminar mixed convection in a vertical pipe were performed for the Re range 1,000-3,000, the $Gr_H$ range $10^5-10^8$, the Pr range 2,000-7,000, and aspect ratio range 1-7. Using the analogy concept, heat transfer systems were simulated by mass transfer systems. A cupric acid.copper sulfate electroplating system was adopted as the mass transfer system, and the mass transfer rates were measured. The measured Nu values were far greater than those previously reported because of the large value of pr in this experiment. As the aspect ratio in this study was not sufficiently large for the flow to be fully developed, the test results were similar to those for mixed convection on a vertical plate rather than that inside a long vertical pipe. It was concluded that the behavior of laminar mixed convection of a developing flow in a vertical pipe at a low aspect ratio and low $Gr_H$ is similar to that of laminar mixed convection in the vertical plate. As the aspect ratio and $Gr_H$ increase, the laminar mixed convection phenomena becomes similar to that observed in a fully developed flow in the vertical pipe.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.311-314
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• 2006

This paper concerns about total dynamic analysis of integrated mining system. This system consists of vertical steel pipe, intermediate buffer station, flexible pipe and self-propelled miner. The self-propelled miner and buffer are assumed as rigid-body of 6-dof. Discrete models of vertical steel pipe and flexible pipe are adopted, which are obtained by means of lumped-parameter method. The motion of mining vessel is not considered. Instead, the motion of mining vessel is taken into account in form of various boundary conditions (e.g. forced excitation in slow motion and/or fast oscillation and so on). A terramechanics model of extremely soft cohesive soil is applied to the self-propelled miner. The hydrodynamic forces and moments are included in the dynamic models of vehicle and lifting pipe system. Hinged and fixed constraints are used to define the connections between sub-systems (vertical steel pipe, buffer, flexible pipe, miner). Equations of motion of the coupled model are derived with respect to the each local coordinates system. Four Euler parameters are used to express the orientations of the sub-systems. To solve the equations of motion of the total dynamic model, an incremental-iterative formulation is employed. Newmark-b method is used for time-domain integration. The total dynamic responses of integrated mining system are investigated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.9
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• pp.2916-2923
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• 1996

A numerical analysis of the moving bed heat exchanger of solid particles inside the vertical pipe was performed using finite difference method. Also, the theoretical solutions were obtained for comparison when the wall heat flux or the wall temperature was assumed constant. The comparison showed that their results agreed well each other. The moving bed heat exchanger was classified as countercurrent-flow, parallel-flow, and cross-flow types according to the gas flow direction. For each type, the thermal efficiency of heat exchanger was calculated as a function of non-dimensional parameters such as the characteristic length of heat exchanger, Biot number and the ratio of thermal capacities of gas and solid particles.

• Journal of the Korean Society of Visualization
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• v.22 no.1
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• pp.68-78
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• 2024

The stratification phenomena of still hydrogen (20%) and methane (80%) gas mixture in a vertical urban gas pipe have been investigated by simulating the flows based on a mixture model. The stratification is accompanied with the natural convection by the buoyancy force. The hydrogen volume fraction in the upper sections of the pipe increases with time but the increasing rate gets smaller due to the weaker buoyancy force. The pipe with a smaller diameter exhibits a higher peak of hydrogen concentration. The size of vortices is proportional to the pipe diameter. The slip velocity between hydrogen and methane oscillates with a large amplitude at the earlier stage of stratification and then the amplitude decreases sharply. The slip velocity decreases with the diameter, making the stratification become slower. The length of pipe does not affect the stratification since the pipe is sufficiently long relative to the size of vortices.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.233-238
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• 2014

In case of the slender mass concrete like attached wall, retaining wall and bridge tower, the low heat cement and the control joint are mainly used for thermal cracking control. However, even if these cracking control methods are considered, it is impossible to control thermal cracks perfectly, because the external restraint is largely in these mass concrete. Because these cracks occurring in slender mass concrete members almost penetrate concrete member, the special cracking control is demanded in these mass concretes. The vertical pipe cooling method improving existing pipe cooling method was developed for the active thermal cracking control of slender mass concrete, and applied at the field attached wall. In results, the maximum temperature dropped more than $10^{\circ}C$ by vertical pipe cooling method, and the cracks decreased about more than 50%.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.160-163
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• 2001

In order to develop a nodule conveying system through a flexible pipe out of the deep-seabed manganese nodule miner, an experimental study of the solid-water slurry flow in vertical pipe is performed as the first stage of total experiments. Hydraulic characteristics of the pipe slurry flow such as slip velocity, transport concentration and pressure gradient are investigated for the size of particle, load ratio, and flow rate of water. The higher the load ratio is, the larger the transport concentration and pressure gradient become. The bigger the size of particles is, the larger the pressure gradient becomes. The effectiveness of the flow rate to hydraulic performance is also investigated. This results are to be used for designing crusher and pump, and operating the conveying device.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.5
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• pp.391-397
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• 2002

Pressure drop were experimentally investigated for ice slurry flowing in the acrylic pipes with inner diameter of 24 mm. Ice slurry was made from 6.5% ethylene glycol-water solution, and the pipes is consisted of horizontal, vertical (upward and downward) and $90^{\circ}$ elbow pipe. The ice Packing factor (IPF) and the flow rate of the experiments were varied from 0 to 30% and from 5 to 70kg/min respectively The measured pressure drop in various pipe positions were compared with those for the solution flow (IPF=0). The pressure drop was larder than that for solution flows as the IPF increased when the flow rate was low or very high. Sharp increases in pressure drop were observed for the cases when IPF is more than 70% in horizontal and vertical pipes, whereas the pressure drop increased with the IPF simultaneously in an elbow pipe.