• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.5
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• pp.36-41
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• 2008

Multi-ply sheet forming has many advantages including the possibility of using wide range of materials in a given structure, lowering production cost, making higher grammage products and so on. But, incorrect structure of sheet makes flow resistance higher so that it shows poor dewatering in press section. One of major factors that affect sheet structure and dewatering property is fines content in each layer. We, therefore, examined the press dewatering of multi-ply sheet that has the different fines content in each layer and the effect of fines distribution on physical properties of sheet to find a technology for optimum utilization of raw materials. In case of two layered sheet, the sheet which was composed of layers with the different flow resistance showed higher dewatering rate than one which has the same flow resistance. And the more difference in fines content for layers existed, the more dewatering occurred. For three layered sheets, dewatering is mainly dependent on fines content of bottom layer. Strength properties were affected by dewatering degree and multi-ply sheet structure.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.188-191
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• 1993

Silicon flow sensor which can detect the magnitude and direction of two dimensional air flow was designed and fabricated by CMOS process and bulk micromachining technique. The flow sensor consists of three-layered dielectric diaphragm a heater at the center of the diaphragm and four thermopiles surrounding the heater at each side of diaphragm as sensing elements. This diaphragm structure contributes to improve the sensitivity due to excellent thermal isolation property of dielectric materials and its tiny thickness. The flow sensor has good axial symmetry to sense 2-D air flow with the optimized sensing position in the given structure. Measured sensitivity of our sensor is $18.7mV/(m/s)^{1/2}$.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.2
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• pp.197-215
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• 2015

Modeling water flow in variably saturated, porous media is important in many branches of science and engineering. Highly nonlinear relationships between water content and hydraulic conductivity and soil-water pressure result in very steep wetting fronts causing numerical problems. These include poor efficiency when modeling water infiltration into very dry porous media, and numerical oscillation near a steep wetting front. A one-dimensional finite element formulation is developed for the numerical simulation of variably saturated flow systems. First order backward Euler implicit and second order Crank-Nicolson time discretization schemes are adopted as a solution strategy in this formulation based on Picard and Newton iterative techniques. Five examples are used to investigate the numerical performance of two approaches and the different factors are highlighted that can affect their convergence and efficiency. The first test case deals with sharp moisture front that infiltrates into the soil column. It shows the capability of providing a mass-conservative behavior. Saturated conditions are not developed in the second test case. Involving of dry initial condition and steep wetting front are the main numerical complexity of the third test example. Fourth test case is a rapid infiltration of water from the surface, followed by a period of redistribution of the water due to the dynamic boundary condition. The last one-dimensional test case involves flow into a layered soil with variable initial conditions. The numerical results indicate that the Crank-Nicolson scheme is inefficient compared to fully implicit backward Euler scheme for the layered soil problem but offers same accuracy for the other homogeneous soil cases.

• 한국가시화정보학회:학술대회논문집
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• 2003.11a
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• pp.75-78
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• 2003

An interfacial instability has recently been observed for the DC- and AC-powered electroosmotic flows of the two miscible electrolyte layers having different concentrations in microchannels. It is rather contrary to our common belief that the flow inside a microchannel is generally stable due to the dominant role of the viscous damping. In this work, we visualized the electroosmotic flow inside a T-channel to validate the numerical predictions. It is clearly shown that the strong vortices (which characterize the interface shapes) are generated at the interface of the two fluids, as was predicted in the numerical analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1321-1329
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• 1989

본 논문에서는 성층화된 용액ㅇ네 수평방향으로 온도구배가 가해지는 경우에 있어서 두 부력인자의 상대적 크기에 따라 나타나는 유동형태와 그에 따른 온도, 농도 분포 및 열전달특성을 수치적으로 연구하고자 한다.

• Journal of Korea Soil Environment Society
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• v.2 no.3
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• pp.59-67
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• 1997

To investigate the effects of organic matter and soil depth on soil water flow in a multi-layered soil, the saturated hydraulic conductivities(Ksat) were measured from the single- and multi-layered soil columns, that the soils were mixed with the oven-dried cow manure compost(CMC) at 4 different ratios such as 0, 2, 4, and 6% on a weight basis. The measured hydraulic conductivities(Ksat) were compared with theoretical hydraulic conductivity (Keff calculated by Jury's equation of effective hydraulic conductivity. In the single layered soil column saturated hydraulic conductivities(Ksat) were significantly decreased with increasing the application rate of compost. In the multi-layered the soil columns Ksat was also decreased with increasing rate of compost and soil depth. Calculated Keff showed the similar results of Ksat as obtained from the measured Ksat, whereas steadily increased with increasing soil depth. Therefore, modification of Jury's equation should be required to adapt theoretical Keff for Held application.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.87-92
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• 2016

The importance of heat dissipation for the electric device modules along the thickness direction is increasing. Two types of two-layered materials, metal-metal bonding and dielectric-metal bonding, have been fabricated by roll bonding process and a thermal diffusivity of the specimens was measured along the thickness direction. The thermal diffusivity of specimens with metal-metal bonding measured by light flash analysis (LFA) showed a same value independent on the direction of heat flow. However, the thermal diffusivity of specimens with dielectric-metal bonding showed a big difference of 17.5% when the direction of heat flow changed oppositely in the LFA process. The measured thermal diffusivity of specimens when the heat flows from metal to dielectric direction showed smaller value of 17.5% compared to the value when the heat flow from dielectric to metal direction. The difference in thermal diffusivity of specimens with dielectric-metal bonding dependence on direction of heat flow is due to the electron-phonon resistance that occurred transfer process of electron energy to phonon energy near the interface.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.225-226
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• 2009

• Proceedings of the Korean Fiber Society Conference
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• 2001.04a
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• pp.217-220
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• 2001

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.332-342
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• 2010

A model has been developed to investigate in-river sediment and phosphorus dynamics. This advective-dispersive model is coupled with hydrodynamics and sediment transport submodels to simulate suspended sediment, total dissolved phosphorus, total phosphorus, and particulate phosphorus concentrations under unsteady flow conditions. It emphasizes sediment and phosphorus dynamics in unsteady flow conditions, in which the study differs from many previous solute transport studies, conducted in relatively steady flow conditions. The diffusion wave approaximation was employed for unsteady flow simulations. The first-order adsorption and linear adsorption isotherm model was used on the basis of the three-layered riverbed submodel with riverbed sediment exchange and erosion/deposition processes. Various numerical methods were tested to select a method that had minimal numerical dispersion under unsteady flow conditions. The responses of the model to the change of model parameter values were tested as well.