• Membrane Journal
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• v.16 no.4
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• pp.303-312
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• 2006

The asymmetric hybrid membranes of polyethersulfone (PES) and $ZrO_2$ nanoparticles were prepared via new one-step procedure combining simultaneously the phase-inversion method and the sol-gel technique. The optimum contents of $Zr(PrO)_4\;and\;HNO_3$ catalyst were determined by the adsorption experiments of phosphate anion onto the resulting hybrid membranes. The maximum adsorption of phosphate anion is obtained at the conditions of 0.15 mL $Zr(PrO)_4$ addition per 1 mL PES and 30 mL $HNO_3$ addition per 1 mL $Zr(PrO)_4$. Variation of morphology, performance and incorporated $ZrO_2$ amount of the resulting hybrid membranes were discussed and determined using SEM, pure water flux, TGA, ICP, XRD and contact angle measurements. Increasing $Zr(PrO)_4$ addition into casting solution, pure water flux is increased and $ZrO_2$ amount in the hybrid membrane is maximized at the conditions 0.15 mL $Zr(PrO)_4$ addition per 1 mL PES. The prephosphatation of PES-$ZrO_2$ hybrid membrane was studied to modify the surface characteristics of membrane. Ultrafiltration of bovine serum albumin (BSA) solution was performed in a dead-end cell using both a bare (non-phosphated) and a phosphated hybrid membrane. It is revealed that both the permeate flux and BSA rejection were increased as about 40% by prephosphatation of hybrid membrane. These results may be explained on the basis of the increase of membrane hydrophilicity, which was determined from contact angle measurements.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.1
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• pp.23-33
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• 2015

This study was carried out for the purpose of minimizing the area of rapid flow inside the water tank. And the shape of incurrent canal was improved, and then the characteristics of fluid flow occurring inside the water tank was analyzed by using the Computational Fluid Dynamics (CFD) simulation method. better multiple hoe screw nozzle incurrent canal was used instead of conventional drop current canal used for the water tank. And according to the results of analyzing the characteristics of fluid flow, in case a screw blade was installed inside the nozzle, fluid flow was sprayed wide. And wide fluid flow was shown inside the cylindrical water tank too. Besides, a tracer simulation was carried out, in case of installing 1 and 2 multiple hoe screw nozzle incurrent canals at the cubic water tank. As a result, MODAL, MODAL index value was close to 1, in case of installing 2 canals. Therefore, it was possible to obtain the results of being close to the characteristics of plug flow.

• Korean Journal of Food Science and Technology
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• v.53 no.2
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• pp.218-222
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• 2021

This study aimed to investigate bacterial disinfection in drinking water using a water purifier. Water artificially inoculated with Escherichia coli and Listeria monocytogenes at various concentrations was irradiated using ultraviolet (UV)-C at a rate of 3.4 L/min in a water purifier, and the disinfection effects of UV-C were evaluated. Both E. coli and L. monocytogenes were disinfected up to 107 colony-forming units (CFU)/2.8 L by the UV-C irradiation. Additionally, morphological study using fluorescence microscopy in conjunction with live/dead staining revealed that both the bacteria species were disinfected by the UV-C irradiation. Therefore, UV-C in water purifiers can effectively kill high concentrations of bacteria in distilled water. UV irradiation (UV-C: 254 nm wavelength, irradiation dose: 40 mJ/㎠) at a flow rate of 3.4 L/min on drinking water has the potential to sterilize bacteria-contaminated drinking water, at least for 3.2×107 CFU/2.8 L of E. coli and 8.4×107 CFU/2.8 L of L. monocytogenes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.1-10
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• 2021

In this study, a circular pipe can be installed by suction pressure for construction on soft ground with a low-water level. A series of laboratory-scale model tests were conducted in sandy ground to comprehend the suction pressure of the circular pipe in low-water levels. For repeated tests on saturated sandy soil, a container was mounted with three vibration generators on the floor. A repetitive vibration was applied using the vibration system for ground compaction. In the model tests, different diameters and thicknesses on saturated sandy soil with a water depth were considered. The result showed that the suction pressure increased with increasing penetration depth of the circular pipe. Moreover, the suction pressure required to penetrate the pipe decreased with increasing diameter. In the low-water level, the total suction pressure measured at the top lid increased because additional suction pressure is required to lift the water column. On the other hand, this led to a decrease in suction pressure to penetrate the circular pipe because the weight of the water column is applied as a dead load. Therefore, it is necessary to consider the water level to design the required suction pressure accurately.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.4
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• pp.421-428
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• 2005

Dissolved air flotation (OAF) is a solid-liquid separation system that uses fine bubbles rising from bottom to remove particles in water. In this study, we investigated the effect of L/W (L; Length, W; Width) on the hydro-dynamic behavior in DAF system using CFD (Computational Fluid Dynamics) and ADV (Acoustic Doppler Velocimetry) technique. The factual full-scale DAF system, L/W ratio of 1:1, was selected and various L/W ratio (2:1, 3:1, 4:1 and 5:1) conditions were simulated with CFD. For modelling, 2-phase (gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using an Eulerian-Eulerian approach based on the assumption that very small particle is applied in the DAF system. Also, for verification of CFD simulation results, we measured the factual velocity at some points in the full-scale DAF system with ADV technique. Both the simulation and the measurement results were in good accordance with each other. As the results of this study, we concluded that L/W ratio and outlet geometry play important role for flow pattern and fine bubble distribution in the flotation zone. In the ratio of 1:1, the dead zone is less than those in other cases. On the other hands, in the ration of 3:1, the fine bubbles were more evenly distributed.

• Journal of computational fluids engineering
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• v.21 no.4
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• pp.40-45
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• 2016

The numerical simulation has been performed to predict the performance of the fire suppression system for cabin of shipboard enclosure. The present study aims ultimately at finding the optimal parametric conditions of the mist-injecting nozzles using the CFD methods. The open numerical code was used for the present simulation named as FDS (Fire Dynamics Simulator). Application has been done to predict the interaction between water mist and fire plume. In this study, the passenger cabin was chosen as simulation space. The computational domains for simulation in the passenger cabin were determined following the fire scenario of IMO rules. The full scale of the flow field is $W{\times}L{\times}H=4{\times}3{\times}2.4m^3$ with a dead zone of $W{\times}L{\times}H=1.22{\times}1.1{\times}2.4m^3$. The water mist nozzle is installed in ceiling center of 2.3 m height from the floor, and there are six mattresses and four cushions in the simulation space. The combination patterns of orifices to the main nozzle and the position to install nozzles were chosen as the simulation parameters for design applications. From the present numerical results, the centered-located nozzles having evenly combined orifices were shown as the best performance of fire suppression.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.11
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• pp.607-618
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• 2015

This study was conducted to suggest hydraulic modification for improving evenness of inlet flow distribution into side stream type low-pressure MF (microfiltration) module using CFD (computational fluid dynamics) simulation and PIV (particle image velocimetry) techniques. From the results of CFD simulation for various typed inlet structure, it was investigated that installing internal orifice baffle in inlet the distribution channel could improve the evenness of inlet flow distribution over about 40%. Also, from the results of PIV measurements which were carried out for verifying the CFD simulation, it was observed that the momentum of the water body coming from the opposite side of the inlet was relatively larger. This momentum would generate strong shear force in the near of inlet side wall. On the other hands, occurrence of dead zone and eddy flow was confirmed in the opposite side.

• Journal of Korean Society on Water Environment
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• v.20 no.1
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• pp.48-54
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• 2004

Two methods, a Ceriodaphnia algal uptake suppression test (CAUST) and a new toxicity test based on temperature control (TTBTC) which are based on feeding behaviour and temperature control, respectively, were developed and compared for the adoption as the better methodology for short-term toxicity screening. As previously published by Lee et aI., (1997), the CAUST method is based on the feeding behaviour of C. dubia and requires as little as 1 hour of contact time between C. dubia neonates and toxicant. However, even though CAUST requires only 1 hour of contact time, this method still take many hours for the preparation and measurement. Before the test starts, neonate digestive tracts were cleared by feeding yeast to the daphnids, Neonates were then exposed to toxicant, followed by addition of Scenedesmus subspiatus into the bioassay vessels. Daphnids were examined under the bright-field microscope with the presence of algae (indicated by a green colored digestive tract) or the absence of algae. Uptake indicated no toxic effect, whereas, absence of uptake indicated toxic inhibition. Unlike CAUST, the newly developed method (TTBTC) is based on just temperature control for the toxicity test of C. dubia. Initially, neonates are exposed to toxicants while the temperature of water bath containing media increased to $35.5^{\circ}C$. After 1.25 hour of contact time, the number of the daphnids, either live (no toxic effect) or dead (toxic effect), is counted without the aid of any instrument. In both methods, median effective concentrations ($EC_{50}$ values) were computed based on the results over a range of dosed toxicant concentrations. It showed that TTBTC was as sensitive as the standard 48-hour acute bioassay and CAUST. TTBTC and CAUST were much more sensitive than the I-hour I.Q. test and 30-minute Microtox. This study indicates that TTBTC is an easier and more rapid toxicity test than the standard 48-hour acute bioassay and even CAUST.

• Korean Journal of Veterinary Service
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• v.26 no.2
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• pp.135-144
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• 2003

Fowl typhoid is a septicemic disease of turkeys and chickens. The antigen is Salmonella(S) gallinarum, which cross-reacts with S pullorum because of common antigen. The organism is maintained in the ovary of carrier birds and transmitted vertically in the york. It is also transmitted horizontally through feces and broken eggs. The symptoms are weakness, drowsiness, wing drooping, hyperexcitability, paresis and diarrhea. In the many cases, the birds are found dead in the morning before any symptoms have been noticed. this experiment was carried out to investigate the characteristics of S gallanarum and scrutinized about the control systems. 1. Fowl typhoid was came about in the winter than the other seasons. The average of mortality was 46.3%. And it was came about not only adult poultry but also chicks. 2. S gallinarum was isolated from liver and spleen in infected chickens. Total isolated strains were 60. 3. The organisms were all extinct at 60$^{\circ}C$, 30mins. 4. A survival rate was higher in underground water than a secondary distilled water. It was detected in underground water until 30 days. 5. When being exposed to the solar light, it became extinct almost within 24 hours. 6. It was survived in a refrigerator until 12 months. 7. It was extinct among 5 mins in 0.1% phenol and 2% formalin. 8. When the cultured organism fluid was inoculated in SD-rat abdominal cavity, rat died within 24 hours. 9. Pullorum-typhoid related program must disciplines in order to destroy the fowl typhoid, and breeding system must be converted to cage system.

• Journal of Pharmacopuncture
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• v.17 no.3
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• pp.7-15
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• 2014

Objectives: The present study investigated the toxic properties of petroleum ether extract of Wattakaka (W.) volubilis in Wistar female rats. Methods: An in vitro brine shrimp lethality bioassay was studied in A. Salina nauplii, and the lethality concentrations were assessed for petroleum ether extract of W. volubilis. A water soluble portion of the test extract was used in different concentrations from $100-1000{\mu}g/mL$ of 1 mg/mL stock solution. A 24-hours incubation with a 1-mL aliquot in 50 mL of aerated sea water was considered to calculate the percentage rate of dead nauplii with test extract administration against a potassium-dichromate positive control. The acute and the sub-acute toxicities of petroleum ether extract of W. volubilis were evaluated orally by using gavage in female Wistar rats. Food and water intake, body weight, general behavioral changes and mortality of animals were noted. Toxicity or death was evaluated following the administration of petroleum ether extract for 28 consecutive days in the female rats. Serum biochemical parameters, such as alanine aminotransferase (ALT), alkaline phosphatase (ALP), bilirubin, total cholesterol, triglyceride, total protein, glucose, urea, creatinine, sodium, potassium and ${\alpha}$-amylase levels, were measured in the toxicity evaluations. Pathological changes in isolated organs, such as the liver, kidneys, and pancreas, were also examined using hematoxylin and eosin dye fixation after the end of the test extract's administration. Results: The results of the brine-shrimp assay indicate that the evaluated concentrations of petroleum ether extract of W. volubilis were found to be non-toxic. In the acute and the sub-acute toxicity evaluations, no significant differences were observed between the control animals and the animals treated with extract of W. volubilis. No abnormal histological changes were observed in any of the animal groups treated with petroleum ether extract of W. volubilis. Conclusion: These results suggest that petroleum ether extract of W. volubilis has a non-toxic effect in Wistar female rats.