• Advanced Composite Materials
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• v.18 no.2
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• pp.135-152
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• 2009

Liquid molding processes, such as resin transfer molding, involve resin flow through a porous medium inside a mold cavity. Numerical analysis of resin flow and mold filling is a very useful means for optimization of the manufacturing process. However, the numerical analysis is quite time consuming and requires a great deal of effort, since a separate numerical calculation is needed for every set of material properties, part size and injection conditions. The efforts can be appreciably reduced if similarity solutions are used instead of repeated numerical calculations. In this study, the similarity relations for pressure, resin velocity and flow front propagation are proposed to correlate another desired case from the already obtained numerical result. In other words, the model gives a correlation of flow induced variables between two different cases. The model was verified by comparing results obtained by the similarity relation and by independent numerical simulation.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.51-54
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• 2013

Rotary kiln reactors are frequently equipped with an axial burner with which solid burden material is directly heated. Lifters are commonly used along the length of the system to lift particulate solids and increase the heat transfer between the solid bed and the combustion gas. The material cascading from the lifters undergoes drying and reacting through direct contact with the gas stream. In this study, volume distribution of materials held within lifters was modeled according to the different lifter configuration and appropriate configuration was used for the design purpose. This was applied to the one-dimensional heat balance model of a counter-current flow reactor, which contributes to the increase of the effective contact surface, and thereby enhances the heat transfer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.1971-1981
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• 2002

Two-dimensional solidification analysis during rheology forming process of semi-solid aluminum alloy has been studied. Two-phase flow model to investigate the velocity field and temperature distribution is proposed. The proposed mathematical model is applied to the die shape of the two types. To calculate the velocities and temperature fields during rheology forming process, the each governing equations correspondent to the liquid and solid region are adapted. Therefore, each numerical model considering the solid and liquid coexisting region within the semi-solid material have been developed to predict the defects of rheology forming parts. The Arbitrary Boundary Maker And Cell(ABMAC) method is employed to solve the two-Phase flow model of the Navier-Stokes equation. Theoretical model basis of the two-phase flow model is the mixture rule of solid and liquid phases. This approach is based on using the liquid and solid viscosity. The Liquid viscosity is pure liquid state value, however solid viscosity is considered as a function of the shear rate, solid fraction and power law curves.

• Magazine of the Korean Society of Agricultural Engineers
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• v.9 no.2
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• pp.1301-1305
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• 1967

Ground water flow can be studied with model test. Model test of ground water works are necessary for economic and safe design of the works. Also influence of the ground water flow to the durability and safety of hydraulic structures can be studied with this model. a. Sand model ; Water flow through porous media is the principle of sand model. Darcy's formula is the basic equation, $q=k{\frac{dh}{ds}}^{\circ}. The effect of the ground water flow on the grain system itself is represented with this model only. b. Hele-Shaw model ; In this model use is made of the viscous flow analogy. Viscous fluid such as glycerine flowing through two parallel plates depends on Poiseuille law, $q=-c{\frac{dh}{ds}}$. The analogue can be used vertically and horizontally. c. Heat model ; This is based on the analogy of the Fourier's law for heat conduction and Darcy's law for ground water flow. Especially unsteady problem can be studied with this model. A difficulty of the construction of this model is the isolation, which has to prevent losses of the heat. d. Electirc model ; Ohm's law for electric current is analogous to Darcy's law. Resistance material such as metal foil, graphite block, water with salt added, gelatine with salt added, ete. is connected to electric sources and resistor, and equi-voltage line is detected with galvanometer, $N_aCl$, $CuSo_4$, etc. are used as salt in the model. e. Membrane model ; This model is based on the facts that the deflection of a thin membrane obeys Laplace's equation if there is no load in the direction perpendicular to the membrane, and if the dellection is small.

• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.317-323
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• 2008

In the current study, A model for the flow analysis of fresh and highly flowable concrete has been developed using a particle method, the moving particle semi-implicit (MPS) method. The phenomena on the flow of concrete has been considered as a visco-plastic flow problem, and the basic governing equation of concrete particle dynamics has been based on the Navier-Stokes equation in Lagrangian form and the conservation of mass. In order to formulate a visco-plastic flow constitutive law of fresh concrete, concrete is modeled as a highly viscous material in the state of non-flow and as a visco-plastic material in the state of flow after reaching the yield stress of fresh concrete. A flow test of fresh concrete in the L-box was simulated and the predicted flow was well matched with the experimental result. The developed method was well showed the flow motion of concrete particles because it was formulated to be based on the motion of visco-plastic fluid dynamics.

• Journal of the Korean Geotechnical Society
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• v.26 no.11
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• pp.5-15
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• 2010

Debris flow is defined as water mixture flow with wide range of large size soil particles such as rock, gravel and sand. Localized heavy rain, derived from abnormal weather, results in the debris flow which generally occurs in summer, especially during and after rainy season and typhoon. This study focuses on the characteristics of impact force of the debris flow with different gravels and gravel mixtures by model experiment. Based on measured experiment results, it is found that the impact force derived by debris flow is mot proportional to the amount of dry material mixture, but depends on the particle size distribution of the debris flow.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.116-121
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• 1999

Since the material flow near the die part in CONFORM (Continuous Extrusion Forming) process is similar to that of side-extrusion, the side-extrusion model of tube shaped aluminum profiles was studied for the die design in CONFORM process. In this paper, the effects of process parameters in the side -extrusion through a two-hole die face, such as material flow, height and thickness of the tube, velocities of punch and lengths of bearing land were investigated using UBET program and DEFORM commercial FEM code. The optimum lengths of the bearing lands and punch velocities for obtaining the straight shape products required were determined.

• Journal of Biosystems Engineering
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• v.14 no.1
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• pp.33-40
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• 1989

The flow properties of water added com-cob-mix(CCM) were studied in order to provide basic information for designing its pumping system. For the study, a model system similar to actual situation was constructed. From the experiment, it can be concluded that the flow properties of the water added CCM has close relationship with its moisture content as follows; 1. The pressure drop caused by friction was very low when the moisture content of water added CCM was more than 70%. However, when the moisture content of the material is about 60%, the pressure drop increases up to 10 kPa/m at low pumping speed, and 20 kPa/m at high pumping speed, respectively. 2. The water added CCM having about 65% moisture content showed pseudo-plastic flow characteristics. 3. As the moisture content of the material decreases, the shear stress increases more rapidly than the shear rate does. Finally, below approximately 60% moisture, the shear stress becomes a linear relationship with the shear rate. 4. It was possible to pump the material having the moisture content down to 58% through a pipe having 80 mm diameter by a pump operating at 234 rpm. However, by either increasing the diameter of the pipe or decreasing the pumping speed, it can be possible to pump the material having lower moisture content than 55%.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.364-369
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• 1988

In this study, a model for the simulation of the material flow not only inside a robot cell with flexible handling sequence but also between robot cells is presented. A method for the connection of special simulation programs has been developed and a logic model between a real system and a simulation system is employed.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.5
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• pp.136-148
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• 1995

In this study, a model integration method is pressented as a new method for development of a parametric simulation model. This method enable us to integrate the special simulation models for each production subsystem into a large simulation model. Not only this large simulation model but also each special simulation model for each production subsytem can be used independently. Using this integration method man can reduce the development time and cost for simulation model development. To show the usefulness of this method, a simulation model for a production system with robots is developed by this model integration method. This simulation model is realized by the integration of two special simulation models, one model for a machining subsystem and the other model for a transport subsystem. The modeled production system consists of the robotic cells for machining and a transport subsystem which enable the material flow among the robotic cells. The flow of workpiece in each robotic cell is not fixed. All machines in a robotic cell are only served by robots.