• Journal of Biosystems Engineering
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• v.39 no.4
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• pp.310-317
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• 2014

Purpose: This study was conducted to analyze the air flow characteristics in a plant factory with different inlet and outlet locations using computational fluid dynamics (CFD). Methods: In this study, the flow was assumed to be a steady-state, incompressible, and three-dimensional turbulent flow. A realizable k-${\varepsilon}$ turbulent model was applied to show more reasonable results than the standard model. A CFD software was used to perform the numerical simulation. For validation of the simulation model, a prototype plant factory ($5,900mm{\times}2,800mm{\times}2,400mm$) was constructed with two inlets (${\Phi}250mm$) and one outlet ($710mm{\times}290mm$), located on the top side wall. For the simulation model, the average air current speed at the inlet was $5.11m{\cdot}s^{-1}$. Five cases were simulated to predict the airflow pattern in the plant factory with different inlet and outlet locations. Results: The root mean square error of measured and simulated air current speeds was 13%. The error was attributed to the assumptions applied to mathematical modelling and to the magnitude of the air current speed measured at the inlet. However, the measured and predicted airflow distributions of the plant factory exhibited similar patterns. When the inlets were located at the center of the side wall, the average air current speed in the plant factory was increased but the spatial uniformity was lowered. In contrast, if the inlets were located on the ceiling, the average air current speed was lowered but the uniformity was improved. Conclusions: Based on the results of this study, it was concluded that the airflow pattern in the plant factory with multilayer cultivation shelves was greatly affected by the locations of the inlet and the outlet.

• Journal of Pharmacopuncture
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• v.16 no.4
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• pp.30-35
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• 2013

Objectives: This study was designed to investigate the effects of Calculus Bovis-Fel Uris-Moschus pharmacopuncture (BUM) on the regional cerebral blood flow (rCBF) and the mean arterial blood pressure (MABP) in normal and cerebral ischemic rats and to investigate a possible pathway involved in the effects of BUM. Methods: The changes in the rCBF and the MABP following BUM into Fengfu (GV16) were determined by using a laser-Doppler flow meter and a pressure transducer, respectively. Results: BUM significantly increased the rCBF and decreased the MABP in normal rats in a dose-dependent manner. The effect on the rCBF was significantly inhibited by pretreatment with methylene blue (0.01 mg/kg, intraperitoneal), an inhibitor of guanylate cyclase, but was not affected by pretreatment with indomethacin (1 mg/kg, intraperitoneal), an inhibitor of cyclooxygenase. The BUM-induced decrease of the MABP was changed neither by methylene blue nor by indomethacin pretreatment. In the cerebral ischemic rats, the rCBF was stably increased upon cerebral reperfusion in the BUM group in contrast to the rapid and marked increase in the control group. Conclusion: This study demonstrated that BUM into Fengbu (GV16) increased the rCBF in a dose-dependent manner in the normal state; furthermore, it improved the stability of the rCBF in the ischemic state upon reperfusion. Also, the effects of BUM on the rCBF were attenuated by inhibition of guanylate cyclase, suggesting that the effects involved the guanylate cyclase pathway.

• Journal of Korean Society on Water Environment
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• v.27 no.4
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• pp.445-460
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• 2011

The objective of this study was to construct and assess the applicability of the EFDC model for Saemangeum Reservoir as a 3D hydrodynamic and water quality modeling tool that is necessary for the effective management of water quality and establishment of conservation measures. The model grids for both reservoir system only and reservoir-ocean system were created using the most recent survey data to compare the effects of different downstream boundary conditions. The model was applied for the simulations of temperature, salinity, water quality variables including chemical oxygen demand (COD), chlorophyll-a (Chl-a), phosphorus and nitrogen species and algal biomass, and validated using the field data obtained in 2008. Although the model reasonably represented the temporal and spatial variations of the state variables in the reservoir with limited boundary forcing data, the salinity level was underestimated in the middle and upstream of the reservoir when the flow data were used at downstream boundaries; Sinsi and Garyuk Gates. In turn, the error caused to increase the bias of water quality simulations, and inaccurate simulation of density flow regime of river inflow during flood events. It is likely because of the loss of momentum of sea water intrusion at downstream boundaries. In contrast to flow boundary conditions, the mixing between sea water and freshwater was well reproduced when open water boundary condition was applied. Thus, it is required to improve the downstream boundary conditions that can accommodate the real operations of the sluice gates.

• Wind and Structures
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• v.35 no.4
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• pp.255-268
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• 2022

Light-weight or low-damped structures may encounter the unsteady galloping instability that occurs at low reduced wind speeds, where the classical quasi-steady assumption is invalid. Although this unsteady phenomenon has been widely studied for rectangular cross sections with one side perpendicular to the incidence flow, the effect of the mean wind angle of attack has not been paid enough attention yet. With four sectional models of different side ratios and geometric shapes, the presented research focuses on the effect of the wind angle of attack on unsteady galloping instability. In static tests, comparatively strong vortex shedding force was noticed in the middle of the range of flow incidence where the lift coefficient shows a negative slope. In aeroelastic tests with a low Scruton number, the typical unsteady galloping, which is due to an interaction with vortex-induced vibration and results in unrestricted oscillation initiating at the Kármán vortex resonance wind speed, was observed for the wind angles of attack that characterize relatively strong vortex shedding force. In contrast, for the wind angles of attack with relatively weak shedding force, an "atypical" unsteady galloping was found to occur at a reduced wind speed clearly higher than the Kármán-vortex resonance one. These observations are valid for all four wind tunnel models. One of the wind tunnel models (with a bridge deck cross section) was also tested in a turbulent flow with an intensity about 9%, showing only the atypical unsteady galloping. However, the wind angle of attack with the comparatively strong vortex shedding force remains the most unfavorable one with respect to the instability threshold in low Scruton number conditions.

• The Journal of Information Technology
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• v.8 no.2
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• pp.85-91
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• 2005

We studied a pollution mechanism for simulation of contamination environment in industrial concentrated area of around a metropolitan that made to circulated flow in the chamber. In case of the virgin both side of EPDM or Silicon insulator, we confirmed that the pollution to much more than service insulator in the field. Also contamination of initial state of the virgin didn't falling in spite of physical outside factor easily. This study confirmed to that the silicon was too much accumulated pollution contrast to EPDM insulator from scatter(spray) point to regular interval position use the Kaolin contaminant in the chamber. There are effected to the hydrophobicity of polymer insulator due to the pollution. In ceramic insulator, we get to know that pollution is much more at the Post insulator with vertical than with horizontal setup insulator.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.1
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• pp.63-68
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• 2011

Aerodynamic characteristics of a wing during fold motion were investigated in order to understand how variations or changes in such characteristics increase aircraft performance. Numerical simulations were conducted, and the results were obtained using the unsteady vortex lattice method to estimate the lift, drag and the moment coefficient in subsonic flow during fold motion. Parameters such as the fold angle and the fold angular velocity were summarized in detail. Generally, the lift and pitching moment coefficients decreased as the angle increased. In contrast, the coefficients increased as the angular velocity increased.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.189-196
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• 2000

A numerical simulation was conducted to analyze the interaction of flame and vortices. The characteristic scales of flame and vortices were limited in the thin laminar flamelet regime. Within this regime, flame is assumed as discontinuity surface and its motion in flow field was described by G-equation instead of full governing equations. Additional approximations include distribution of line volume sources on flame surface to simulate effect of volume expansion. Contrast to previous calculations, current study employed vortex transport equation to evaluate attenuation and smearing of vortices. Two extreme conditions of frozen vortex and frozen flame were considered to validate the current method. Comparison with direct numerical simulation resulted in satisfactory quantitative agreement with higher computational efficiency which warrants the usefulness of the present model in more complex situation.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.118-123
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• 2004

The combustion characteristics of 0.03MW turbulent methane/oxygen diffusion flames have been investigated to give basic informations for designing industrial oxyfuel combustors. NOx reduction has become one of the most determining factors in the combustor design since 3-5% nitrogen is intrinsically included from the current oxygen producing processes. Flame lengths and NOx concentrations were measured by varying flow velocities with and without installing quarls. Flame stabilities are significantly enhanced by oxyfuel combustion in contrast to air-fuel combustion. Flame length decreases with increasing fuel or oxygen velocity because of the enhancement of turbulent mixing. NOx concentration was reduced with increasing flo velocities. This can be attributed to the entrainment of inert product gases into flame decreasing flame temperature. The installation of quarl on the burners rather increased NOx concentration since the quarl blocked the entrainment above the nozzles.

• YAKHAK HOEJI
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• v.46 no.1
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• pp.6-10
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• 2002

The present study investigated the rheological properties and adjuvant activity of IgG production of ι-Carrageenan prepared using two different methods . incubation at 37.4$^{\circ}C$ after either being heated or not being heated int 6$0^{\circ}C$ for 10 minutes. The carrageenan exhibited plastic flow with thixotropy in both cases, but the viscosity of the sample that had been heated was significantly higher. C57BL/6 mice were then immunized intraperitoneally with either of the carrageenans containing protein antigens. The maximum adjuvant effect was found when using the nonheated carrageenan, especially in term of IgG2a, IgG2b, and IgG3 production. In contrast, IgG1 antibody production was the same far both types of carrageenan. furthermore, when administered oral1y, neither type of carrageenan resulted in the production of any antibodies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.146-149
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• 2004

We have studied a liquid crystal (LC) mode (named locked super homeotropic (LSH)) in which the LCs aligned homeotropically are locked by surrounding walls such as cubic, hexagonal and cylinder. In the device, the vertically aligned LCs tilt down symmetrically around the center of the cell when a voltage is applied and thus it exhibits wide viewing angle. The structure of this LSH mode is suitable for large-sized display panels. since the LCs are locked in micro domains the LCs do not flow to the bottom of the panel by gravity. This mode is applicable to achieve high performance TFT-LCD TV because of high performance characteristics such as high contrast, high brightness, wide-viewing angle.