• Journal of the Korean Electrochemical Society
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• v.8 no.1
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• pp.47-54
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• 2005

This article covers the fundamentals of stress-induced diffusion, focusing on the theoretical model for hydrogen transport through self-stressed electrode. First, the relationship between hydrogen diffusion and macroscopic deformation of the electrode specimen was briefly introduced, and then it was classified into the diffusion-elastic and elasto-diffusive phenomena. Next, the transport equation for the flux of hydrogen caused simultaneously by both the concentration gradient and the stress gradient was theoretically derived. Finally, stress-induced diffusion was discussed on the basis of the numerical solutions to the derived transport equation under the permeable and impermeable boundary conditions.

• Kyungpook Mathematical Journal
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• v.58 no.3
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• pp.533-546
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• 2018

The object of this work is to study the existence of solutions for a class of p(x)-Kirchhoff type problem under no-flux boundary conditions with dependence on the gradient. We establish our results by using the degree theory for operators of ($S_+$) type in the framework of variable exponent Sobolev spaces.

• Progress in Superconductivity and Cryogenics
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• v.24 no.3
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• pp.7-11
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• 2022

We are conducting research and development of magnetic filters for magnetic separation targeting paramagnetic materials. In order to develop a new magnetic filter with a large magnetic gradient, stainless fiber (SUS430, 120 mm × 3 mm) with a triangular cross section was sintered with a high void ratio (~ 70%) and the magnetic filter (20 mm × 2 mm) was created. When this magnetic filter was used to perform magnetic separation of hematite (particle size 50 ㎛) under a maximum magnetic flux density of 1.49 T, high separation rates were obtained.

• Proceedings of the Korean Magnestics Society Conference
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• 1993.11a
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• pp.26-27
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• 1993

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.58-58
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• 2001

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.86-86
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• 2022

While estuarine dams can develop freshwater resources and block the salt intrusion, they can result in increased sediment deposition in the estuary. The mechanism of increased sediment deposition in an estuary with an estuary dam is not well understood. To fill this knowledge gap, 7 ADCP measurements of flow and suspended sediment concentration (SSC) were collected along-channel in an estuary with an estuarine dam over a neap-spring cycle. Flow and SSC were used to calculate the sediment flux and sediment flux gradients. The results indicated that the cumulative sediment fluxes at all stations were directed landward. The along-channel sediment flux gradient was negative, which indicated deposition along the channel. The landward mean-flow fluxes were dominant in the deep portion of the channel near the estuary mouth, whereas landward correlation fluxes were dominant in the shallow portion of the channel near the estuarine dam. The tides were the dominant forcing driving the sediment fluxes throughout the estuary.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.221-226
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• 1999

A data assimilation system for a 1-dimensional mixed layer model has been constructed using the adjoint method. The classical adjoint method does not work well for the mixed layer variabilities due to the occurrence of spikes in the gradient of the cost function. To solve this problem, the two techniques of scaling the cost function and optimization in the frequency space are used. As a result, the heat flux can be reliably estimated with an accuracy of 8Wm$^{-2}$ rms error in the identical twin experiments. We then applied this system to the tropical Pacific TOGA-TAO buoy data. The air-sea heat flux as well as the mixed layer variability were estimated in close approximation to the buoy data, particularly on time scales longer than the seasonal one.

• Journal of the Korean Mathematical Society
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• v.50 no.1
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• pp.81-93
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• 2013

We consider a distributed optimal flux control problem: finding the potential of which gradient approximates the target vector field under an elliptic constraint. Introducing the Lagrange multiplier and a change of variables the Euler-Lagrange equation turns into a coupled equation of an elliptic equation and a reaction diffusion equation. The change of variables reduces iteration steps dramatically when the Gauss-Seidel iteration is considered as a solution method. For the elliptic equation solver we consider the Cell Boundary Element (CBE) method, which is the finite element type flux preserving methods.

• Journal of computational fluids engineering
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• v.11 no.1 s.32
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• pp.36-42
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• 2006

The existing numerical approximations of convection flux, especially the spatial higher-order difference schemes, in unstructured cell-centered finite volume methods are examined in detail with each other and evaluated with respect to the accuracy through their application to a 2-D benchmark problem. Six higher-order schemes are examined, which include two second-order upwind schemes, two central difference schemes and two hybrid schemes. It is found that the 2nd-order upwind scheme by Mathur and Murthy(1997) and the central difference scheme by Demirdzic and Muzaferija(1995) have more accurate prediction performance than the other higher-order schemes used in unstructured cell-centered finite volume methods.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.2
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• pp.69-75
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• 2004

In this paper, we propose the shape of extremely small thrust VCM for application of the Nanoindenter, which enables control of very small force and displacement. We performed optimization of the VCM shape using conjugated gradient method. And the purposes of optimization are the minimization of the permanent magnet size for the efficient systems, minimization of deviation of flux density from the air gap for operate on regular thrust and a linearization of thrust for a good control characteristic. The finite element method is used for characteristic analysis. The node moving method is used to redundant changes of design variables. As a result, the VCM produces a yew small force by the difference of flux density of lower part from higher one. Also, in a wide range of current (0［A］-1［A］), the VCM produces linear driving thrust by saturating the magnetic circuit path and operate on regular thrust by minimizing deviation of flux density of the air gap.