• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.3
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• pp.157-170
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• 2002

To examine the structure and distribution of the Keum River plume produced by continuous river discharge we carried out three-dimensional numerical model experiments with or without Coriolis force and tide. When Coriolis force is included but tide is not the model plume forms the clockwise circulation north of southern channel in the developing stage. As the plume expansion progresses the center of circulation moves to the southwest, with fuming the discharging axis of low-salinity water to the southwest from the mouth of southern channel. These results are explained mainly in terms of barotropic geostrophy by surface slope maintained with accumulated low-salinity(buoyant) water in front of the estuary mouth due to of offshore strong salinity front. When the M$_2$ tide is included the model plume extends farther to the northwest, forming large tongue-like salinity distribution. The tidally averaged surface flows of the offshore plume are mainly in geostrophic balance. These changes in plume distribution are explained in terms of low-salinity water advection by tidal excursion and active tidal mixing; the former supplies low salinity water to the north off the estuary mouth and the later increases mean sea level along the plume and surface salinity in northern shallow coastal area. The main features of observed Keum River plume(Lee et al., 1999; Choi et al., 1999), which showed the northwestward deflection of the plume axis and northward deepening of the plume thickness from the estuary mouth region, are well reproduced by the model in which tide is included.

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.98-105
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• 1999

In the present study, buoyant force and its stabilizing effects in an electrostatic field were examined systematically in order to reduce the effect of natural convection with thermal stratification in a horizontal fluid-saturated porous layer. The correlation of ionic mass transport induced by double-diffusive convection in a horizontal porous layer has been derived theoretically. And the theoretical model was examined by electrochemical experiments. The theoretical correlation for mass transport which is satisfying Forchheimer's flow equation and based on the micro-turbulence model is derived as a function of soltual Darcy-Rayleigh number, thermal Darcy-Rayleigh number and Lewis number. In the experiment, the mass transport of copper ions in $CuSO_4-H_2SO_4$ solution is measured by electrochemical technique. By assembling theoretical correlation and experimental results, the mass transport correlation induced by double-diffusive convection is proposed as $$Sh=\frac{0.03054(Rs_D-LeRa_D)^{1/2}}{1-3.8788(Rs_D-LeRa_D)^{-1/10}}$$ The present correlation looks flirty reasonable with comparing experimental results, and very promising for the applications of its prototype into various systems involving heat transfer as well as mass transfer, in order to control the effects of natural convection effectively.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.1
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• pp.95-107
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• 2016

Ground water is one of important parameters in the designs of underpass structures because urban areas are characterized by soil ground which is relatively permeable than rock ground and a high level of ground water due to low elevation. Therefore, it is important properly to predict variations of the ground water when they can affect underpass structures. In this study, a series of numerical analyses are performed to predict the variations of ground water levels considering the degree of surface imperviousness and LID(Low Impact Development) application. In turn the stability of underground structure is assessed using predicted ground water level. The results show that an increase in the impervious surface area decreases the ground water level. The application of permeable pavement as a LID facility increases the ground water level, improving the infiltration capacity of rainfall into the ground. Seasonal variations of the ground water level are also verified in numerical simulation. The results of this study suggest that reasonable designs of underpass structures can be obtained with the suitable prediction and application of the ground water level considering the surface characteristics.