• Journal of Fisheries and Marine Sciences Education
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• v.6 no.1
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• pp.58-76
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• 1994

Heat transfer and pressure drop measurements are made on low integral-fin tubes in turbulent water flow condition. The integral-fin tubes investigated in this paper are nominally 19mm in diameter. Eight tubes have been used with trapezoidally shaped integral-fins having fin density from 748 to 1654 fpm and 10, 30 grooves. Plain tube having same diameter as finned tube is also tested for comparison. Experiments are carried out using R-11 as working fluid. The refrigerant condensates at a saturation state of $30^{\circ}C$ on the outside tube surface cooled by coolant. The amount of noncondensable gases present in the test loop is reduced to a negligible value by repeated purging. For a given heat input to the boiler and given cooling water flow rate, all test data are taken on steady state. The heat transfer loop is used for testing single long tubes and cooling water is pumped from a storage tank through filters and flowmeters to the horizontal test section where it is heated by steam condensing on the outside of the tube. The pressure drop across the test section is measured by means of pressure gauge and manometer. Each tube tested is cleaned with sodium dichromate pickling solution and well rinsed with water prior to installation in the test section. The results obtained in this study is as follows : 1. Based on inside diameter and nominal inside area, heat transfer of finned tube is enhanced up to 4 times as that of a plain tube at constant Reynolds number and up to 2 times at constant pumping power. 2. Friction factors are up to 1.6~2.1 times those of plain tube. 3. At a given Reynolds number, Nusselt number decrease with increasing pitch to diameter. 4. The constant pumping power ratio for low integral-fin tubes increase directly with the effective area to the nominal area ratio, and with the effective area diameter ratio.

• Economic and Environmental Geology
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• v.47 no.2
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• pp.107-119
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• 2014

NMC Moland mine, which is classified as a contact replacement or skarn deposit, has been interpreted to have been formed by Daebo igneous activity which intruded into the Joseon Supergroup, because it is quite closely located to Jecheon granite. However, an alternative interpretation was recently suggested that the mine could be related with the hydrothermal fluid originated from Cretaceous granitic rocks, bringing about skarnization and Mo mineralization. Here we present an interpretation on the source granite of the mine based on the gravity exploration: the gravity anomaly, unlike the surface geology, shows that the Muamsa granite could be the related granite of the mine, because its hidden subsurface structure is expected to be more widely extended to surrounding area of the mine and deeper than the Jecheon granite.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.5
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• pp.17-28
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• 2018

Cyclonic-dissolved air flotation(Cyclonic-DAF), an advanced form of pressure flotation, applies a structure that enables the forming of twirling flows. This in turn allows for suspended matter to adhere to microbubbles and float to the surface of a treatment tank during the process of intake water flowing through a float separation tank. This study conducted a lab-scale test and pursued geometrical modeling using computational fluid dynamics(CFD) to establish a pilot scale design. Based on the design parameters found through the above process, a pilot cyclonic-DAF system($10m^3/hr$) for removing algae was created. Upon developing the pilot-scale cyclonic-DAF system, a type of algae coagulant(R-119) was applied as the coagulant to the system for field testing through which the removal rates of chlorophyll-a and cyanobacteria were evaluated. The chlorophyll-a and harmful cyanobacteria of the raw water at region B, the field-test site, were found to be $177.9mg/m^3$ and 652,500cells/mL respectively. Treated waters applied with 60mg/L and 100mg/L of algae coagulant presented removal efficiencies of approximately 95% and 97%, respectively. The cyanobacteria cell number of the treated waters applied with 60mg/L and 100mg/L of algae coagulant both that were equal to or less than 1,000cells/mL and were below attention level criteria for the issuance of algae boundary.

• New & Renewable Energy
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• v.9 no.1
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• pp.6-11
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• 2013

Jeollabuk-do has announced a future plan for the Saemangeum Wind Farm which includes the installation of fourteen wind turbines in a single line, located 500m back from the Saemangeum Seawall. It is anticipated as a positive effect that, for sea breeze blowing toward land, the average wind speed could be accelerated and the wind speed distribution could be uniformized by dint of the seawall, an upstream structure of the turbines. At the same time it is also anticipated as a negative effect that the strength of wind turbulence could be increased due to the flow separation generated at the back end of the seawall. According to the results of the computational fluid dynamics analysis of this paper, it has been observed that, at the 50m zone on the road surface located at the uppermost part of the Saemangeum Seawall, the average wind speed has been accelerated by approximately 6~7% and that wind shear has been decreased by 70%, but this positive effect disappears in the zone situated beyond the 100m from the back end of the seawall. It has also been observed that flow separation exists to a limited extent only below the bottom of the blade-sweeping circle and, furthermore, does not extend very far downstream of the wind. As a conclusion, it can be said that the seawall neither positively nor negatively affects the proposed Saemangeum Seawall Wind Farm layout.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.1
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• pp.55-64
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• 2011

The object of this study was to observe the effects of Scutellariae Radix (SR) aqueous extracts on lipopolysaccharide (LPS)-induced rat acute lung injury. Five different dosages of SR extracts were orally administered once a day for 28 days before LPS treatments, and then 5 hours after lipopolysaccharide treatment, all rats were sacrificed. 8 groups, each of 16 rats per group were used in the present study. Changes on the body weights, lung weights, pulmonary transcapillary albumin transit, arterial gas parameters (pH, $PaO_2$ and $PaCO_2$) bronchoalveolar lavage fluid (BALF) protein, lactate dehydrogenase (LDH) and proinflammatory cytokines tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), interleukin-1${\beta}$ (IL-1${\beta}$) contents, total cell numbers, neutrophil and alveolar macrophage ratios, lung malondialdehyde (MDA), myeloperoxidase (MPO), proinflammatory cytokine TNF-${\alpha}$ and IL-1${\beta}$ contents were observed with histopathology of the lung, changes on luminal surface of alveolus (LSA), thickness of alveolar septum, number of polymorphonuclear neutrophils (PMNs). The results were compared with a potent antioxidant ${\alpha}$-lipoic acid, 60 mg/kg, in which the effects on LPS-induced acute lung injury were already confirmed. The results obtained in this study suggest that over 125 mg/kg of SR extracts showed favorable effects on the LPS-induced acute lung injury, and 250 mg/kg of SR extracts resembling acute respiratory distress syndrome mediated by their antioxidant and anti-inflammatory effects and .as similar to ${\alpha}$-lipoic acid in the present study. Therefore, it is expected that SR will be showed favorable effects on the acute respiratory distress syndrome.

• Journal of Veterinary Clinics
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• v.22 no.4
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• pp.401-403
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• 2005

A seven-year old female captive Japanese macaque (Macaca fuscata) was mobbed by its cage mates and subsequently died due to trauma. An incidental finding of multiple biliary cystadenoma in the liver is herein reported. Grossly, multiple small cysts were observed throughout the surface of the liver. One particular cyst that measured $1.3\times1.2\times1.0cm$ and contained mucinous fluid was observed in the center of the liver. Microscopically the cysts were lined by biliary epithelium that varied from simple cuboidal to columnar cells. Signs of malignancy and metastasis to other organs were not observed. This is the first report of biliary cystadenoma in Japanese macaque.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.365-371
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• 2019

In this study, the flame temperature distribution of the diffusion flame burner for SiO₂ deposition was analyzed by the computational fluid analysis. This corresponds to the previous step for simulating the SiO₂ preform deposition process for manufacturing optical fibers using environmentally friendly raw materials. In order to model premixed combustion, heat flow, convection, and chemical reactions were considered, and Reynolds-averaged Navier-Stokes equations and k-ω models were used. As a result, the temperature distribution of the flame showed a tendency to increase the distance from the nozzle surface to the maximum temperature when the flow rate of the auxiliary oxygen increased. In addition, it was confirmed that the temperature distribution due to incomplete combustion was large in the combustion reaction with a large equivalence ratio of the mixed gas.

• Journal of the Korean Institute of Gas
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• v.5 no.3 s.15
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• pp.1-8
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• 2001

This study was carried out for the purpose of determination of maintenance period and investigation of weak point due to freeze when the gas heater of KOGAS valve station Is not operated in winter season. 3-dimensional non-linear numerical simulation was conducted in order to predict the time and location which bath water in heater reaches to ice point. FLUENT V 5.0, commercial code, is used for thermal fluid flow analysis. We thought this was problem of heat conduction solving the energy equation and modeled gas heater by using the real geometry and scale for performing the 3-dimensional simulation. It was analyzed complex heat transfer phenomena considering convection due to air on surface, conduction in insulation material, natural convection of liquid in heater and heat loss through the pipe.

• Wind and Structures
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• v.30 no.2
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• pp.165-180
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• 2020

To determine tornadic wind loads, the wind pressure, forces and moments induced by tornadoes on civil structures have been studied. However, in most previous studies, only the individual building of interest was included in the wind field, which may be suitable to simulate the case where a tornado strikes rural areas. The statistical data has indicated that tornadoes induce more significant fatalities and property loss when they attack densely populated areas. To simulate this case, all buildings in the community of interest should be included in the wind field. However, this has been rarely studied. To bridge this research gap, this study will systematically investigate the influence of a community of buildings on tornadic wind fields by modeling all buildings in the community into the wind field (designated as "the Community case under tornadic winds"). For comparison, the case in which only a single building is included in the tornadic wind field (designated as "the Single-building case under tornadic winds") and the case where a community of buildings are included in the equivalent straight-line wind field (designated as "the Community case under straight-line winds") are also simulated. The results demonstrate that the presence of a number of buildings completely destroys the pattern of regular circular strips in the distribution of tangential velocity and pressure on horizontal planes. Above the roof height, the maximum tangential velocity is lower in the Community case under tornadic winds than that in the Single-building case under tornadic winds because of the higher surface friction in the Community case; below the roof height, greater tangential velocity and pressure are observed in the Community case under tornadic wind fields, and more unfavorable conditions are observed in the Community case under tornadic winds than under the equivalent straight-line winds.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.7
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• pp.1031-1038
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• 2002

The pressure sensitive paint (PSP) has recently received a considerable attention in the fields of aerodynamics and fluid mechanics as a new revolutionary optical technique to measure pressure fields on a body surface. In this study, the feasibility and effectiveness of the PSP pressure field measurement technique have been investigated experimentally. Seven different PSP formulations including two porphyrins(PtOEP and PtTFPP) and four polymers(Polystyrene, cellulous acetate butyrate, GP-197 and Silicon-708) were tested to check the performance and characteristics of each combination. The static calibration of each PSP formulation was carried out in a constant-pressure chamber. The PSP technique was applied to an oblique impinging jet flow to measure variation of pressure field on the impinging plate at on oblique jet angle of ${\theta}=60^{\circ}$. Pressure field images were captured by an 12bit intensified CCD(ICCD, $1K{\times}1K$)camera. As a result, the dynamic response of PSP depends on the oxygen permeability of polymer and the photochemical interaction between luminophore and polymer as well as the reaction of luminophore itself. The reaction of luminophore was changed by employing different polymers. In conclusion, Among 7 PSP formulation tested, the combination of PtTFPP and cellulous acetate butyrate show the best performance. In addition, the detail pressure field of an oblique high-speed impinging jet was measured effectively using the PSP technique.