• Tunnel and Underground Space
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• v.13 no.6
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• pp.465-475
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• 2003

Groundwater inflow into the caverns constructed in fractured rock mass was simulated by numerical modeling, NAPSAC (DFN, discrete fracture network model) and NAMMU (CPM, continuous porous media model), a finite-element software package for groundwater flow in 3D fractured media developed by AEA Technology, UK. The input parameters for modeling were determined on surface fracture survey, core logging and single hole hydraulic test data. In order to predict the groundwater inflow more accurately, the anisotropic hydraulic conductivity was considered. The anisotropic hydraulic conductivities were calculated from the fracture network properties. With a minor adjustment during model calibration, the numerical modeling is able to reproduce reasonably groundwater inflows into cavern and the travel length and times to the ground surface along the flow paths in the normal, dry and rainy seasons.

• Journal of Radiation Protection and Research
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• v.27 no.1
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• pp.67-75
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• 2002

The groundwater flow and contaminant transport numerical models have been established for understanding the movement of pollutants in surface soil environment. The numerical solutions were compared with the analytic solutions for the verification and the application of the models. The numerical solutions from the groundwater and transport models agreed welt with analytic solutions. Especially, the results of groundwater flow model were validated in one- and two-dimensional heterogeneous media. Therefore, it will represent well the characteristics of the heterogeneous media in the field applications. Also, the phenomena of the pollutant dispersion represented quite well by the advection and the hydrodynamic dispersion in the results of the transport model. The important input factor is the choice of complicated boundary conditions in operating the numerical models. The numerical results are influenced by the choice of the proper boundary conditions.

• Journal of the Korean Graphic Arts Communication Society
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• v.25 no.2
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• pp.29-44
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• 2007

The printing industry is getting more digitalized and integration. It has enabled the interactive information and networking from Pre-Press, Press, to the Post-Press. These are efficient management and the improved process and productivity are getting more important. Such trends improved in the functionality and automation. This paper tries to find out how technology for CIP3/4 -based process may be applied and resolved. Such subject includes the domestic and international cases regarding each manufacturer's CIP3/4 technology types. Another purpose is to emphasize on the needs to establish the environment. Under this environment, it is possible to integrate network in exchangeable form through JDF standard format after CIP3/4. Based on the data from this study, it is expected to collect further substantial data which is related to the domestic printing company's CIP 4 operation. It will be also possible to perform subsequent studies on the proper variables of the market segment. CIP4 stands for "International Cooperation for Integration of Prepress, Press and Post-press, it is an association of around forty international companies, mostly manufacturers of prepress, press and post-press, as well as suppliers and users. In this paper, we studied on the acting application of CIP4 work flow.

• Smart Media Journal
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• v.8 no.4
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• pp.38-45
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• 2019

When there is a spray flow such as from a pesticide nozzle, winds affect the droplet flow of a rotary-wing drone accompanied by a strong wake, with a severe oscillation. Especially, during forwarding flights or when winds come from the side, compare to a simple hovering flight as the droplet is in the effect of aerodynamic drag force, the effect of spraying region becomes even larger. For this reason, the spraying of pesticides using drones may cause a greater risk of scattering or a difference in droplet dispersion between locations, resulting in a decrease in efficiency. Therefore, through proper numerical modeling and its applied simulation, an indication tool is required applicable for the various flight and atmospheric conditions. In this research, we completed both experiment and numerical analysis for the strong downwash from the rotor and flight velocity of the drone by comparing the probability density function of droplet distribution to build a spraying system that can improve the efficiency when spraying droplets in the pesticide spray drone.

• Journal of Korean Society of Water and Wastewater
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• v.13 no.1
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• pp.81-94
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• 1999

This study aims at a proposal of the plan that can improve raw water quality by an experimental study using influent water of Nak-dong river, which has been used as raw water for drinking in U-city, through the establishment of the submerged biofilter process PILOT PLANT of media packing channel method. From the analysis of removal efficiency for each water quality item of the collected sample, following results are obtained. First of all, the removal rate of suspended material, BOD, COD, T-N, TOC, turbidity, and $NH_3$ -N appear 82%, 78%, 42%, 15%, 57%, 43%, 54%, and 55% respectively and it is known that the submerged biofilter process of media packing channel method takes effects on water quality improvement from the above analysis results of water treatment efficiency. And the analyzed results for water temperature, residence time, and activities of microorganism, which can be the factors affect on water quality improvement, are as follows. 1) The removal rate variation of SS, BOD, and COD attendant on water temperature change is examined and it is known that the removal rate increases at $13^{\circ}C$ or above. 2) The removal rate of SS, BOD, and COD attendant on residence time is most active in the range of 0~18hr, 0~1.8hr, 0~2.7hr respectively, so it is found that the removal rate becomes smaller after 2.7hr. 3) From the examination of microorganism activity with the abundance of normal bacteria, it is found that the floating bacteria decrease as the flow distance from raw water inflow point of PILOT PLANT increases, and the adhesive bacteria have no concern with the flow distance. And it its known that the biomass of fine algae decreases as the flow distance from the raw water inflow point of PILOT PLANT increases from the examination with Chl-a.

• Journal of Energy Engineering
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• v.21 no.4
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• pp.419-426
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• 2012

A transient, three-dimensional, two-phase flow analysis code, CUPID, has been developed in KAERI. In this work, we performed a preliminary analysis using the CUPID code to investigate the thermal-hydraulic behavior of the moderator in the Calandria vessel of a CANDU reactor. At first, we validated the CUPID code using the three experiments that were performed at Stern Laboratories Inc. To avoid the complexity to generate computational mesh around the Calandria tube bundles, a porous media approach was applied for the region. The pressure drop in the porous media zone was modeled by an empirical correlation. The results of the calculations showed that the CUPID code can predict the mixed flow pattern of forced and natural convection inside the Calandria vessel very well. Thereafter, the analysis was extended to a two-phase flow condition. Also, the local maximum temperature in the Calandria vessel was plotted as a function of the injection flow rate, which may be utilized to predict the local subcooling margin.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.223-232
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• 2018

Bird screen meshes are installed at the air inlet and outlet ducts of spent fuel storage casks to inhibit the intrusion of debris from the external environment. The presence of these screens introduces an additional resistance to air flow through the ducts. In this study, a porous media model was developed to simplify the bird screen meshes. CFD analyses were used to derive and verify the flow resistance factors for the porous media model. Thermal analyses were carried out for concrete storage cask using the porous media model. Thermal tests were performed for concrete casks with bird screen meshes. The measured temperatures were compared with the analysis results for the porous model. The analysis results agreed well with the test results. The analysis temperatures were slightly higher than the test temperatures. Therefore, the reliability and conservatism of the analysis results for the porous model have been verified.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.1
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• pp.73-79
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• 2009

The hydraulic conductivity of porous media is the most important property in soil characteristics. The hydraulic conductivity is determined by outdoor and indoor methods. Indoor methods normally use soil columns for flow test. Assumption of the column test is that fluid one-dimensionally flows through the column. However, fluids may flow toward the wall of the column, resulting in "boundary flow". This study investigated the effect of boundary flow on the hydraulic conductivity by using a permeameter excluding boundary flow. The results showed that the hydraulic conductivity excluding boundary flow was much smaller than the hydraulic conductivity employing the conventional determination method. This study also investigated the effects of particle size and surfactant on the hydraulic conductivity. As the particle size increased, the hydraulic conductivity was increased. The hydraulic conductivity was reduced by increasing surfactant concentration. The result showed that the viscosity of fluid significantly affected the determination of hydraulic conductivity.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.87-90
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• 2003

In Resin transfer molding (RTM), composite parts are produced by impregnation of a dry reinforcement with liquid matrix resin. Permeability is a key issue in this process. For thin parts, the resin flow in the thickness direction can be neglected. Therefore thin parts are considered as two-dimensional composites. However the resin flow through the thickness is important to thicker parts and we have to consider out-of-plane permeability. This work discusses a method to measure out-of-plane permeability. The flow rate and pressure drop across the porous media were measured. Also one dimensional form of Darcy's law is applied to calculate the out-of-plane permeability of various preforms. The flow is injected uniformly into layers of the preform. And a circular fiber mat with 6cm diameter was cut and flattened from cylindrical mandrel.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.91-98
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• 2004

This paper presented results of the laboratory tests conducted to investigate ultrasonically enhanced flow rate using specially designed and fabricated equipment. Influencing factor, ${\alpha}_i$ was verified to investigate the effect of ultrasound on soil matrix and flowing liquid. The test conditions involve soil types, temperature and ultrasonic energy. The test results indicate that ultrasound enhances the flow rate significantly. The degree of enhancement and the values of influencing factors, however, vary with test conditions.