• Journal of Korean Society of Water and Wastewater
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• v.21 no.2
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• pp.195-201
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• 2007

A submerged flat-sheet membrane separation system integrated with PAC (powdered activated carbon) was used in this research in order to investigate the effects of PAC on the efficiencies of operation and treatment and to evaluate the performance of the system. The experiments were carried out under operating conditions of a filtration rate of 0.38 m/d, water temperature of $20-28^{\circ}C$, and PAC dose of 0 g/L (Run-A) and 20 g/L (Run-B). The influent concentrations of TOC (total organic carbon), $NH_4{^+}-N$ (ammonia nitrogen) and $UV_{254}$ (UV absorbance at 254 nm) were 2.48 mg/L, 1.4 mg/L and 2.53 1/m, respectively. TOC removal of 43.2 and 73.6%, ammonia nitrogen removal of 4.9 and 15.9%, and $UV_{254}$ removal of 20.6 and 31.6% were obtained for Run-A and Run-B, respectively. During an experimental period of 33 days, no change was found in TMP (Run-B), but the TMP in Run-A increased by 5 kPa after 29 days. This research showed that the filtrate quality and the performance efficiency were enhanced when PAC was introduced into the filtration system.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.5
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• pp.410-415
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• 2012

An experimental study is carried out to investigate the near-wake characteristics of a NACA 0018 foil with a flat plate. Two-frame grey-level cross correlation PIV method is used to measure the local flow characteristic around a pitch damping foil to control the vertical motion of high speed crafts in a circulating water channel. The analysis also includes angles of attack 10 and 20 degrees respectively. Reynolds number $Re{\fallingdotseq}3.5{\times}10^4$ based on the chord length(C=100mm) of NACA0018 has been applied during the whole experiments. The distance between the foil and the flat plate is D/C=0.5, 1.0 and 1.5 respectively. The channel effect according as the distance between the foil and the flat plate has a close relation with the velocity distributions around the foil. In the wake of 20-degree of attack, the complex turbulent flow and a thick boundary layer are formed due to the processes of vortex generation and dissipation.

• Membrane Journal
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• v.15 no.3
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• pp.241-246
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• 2005

This study is investigated for the applications of MBR SYSTEM using $ENVIS^{(R)}$ which is a submerged flat membrane for treatment of sewage and wast water. The experiment was practiced on the scene of labor that are sewage facilities of factories $(10\;m^3/day)$ and wast water treatment plant $(30\;m^3/day)$ using equipments made by Pure-Envitech Co., LTD. SS, BOD and COD for the result of removal efficiency at the sewage facilities of factories were $99.7\%,\;97.6\%$, and $96.8\%$, rspectively. SS, BOD and COD for the result of removal efficiency at the waste water treatment plant were $99.6\%,\;95.6\%,\;and\;80.3\%$, respectively.

• Membrane Journal
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• v.24 no.3
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• pp.249-257
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• 2014

This experiment was carried out for a laboratory scale activated sludge bioreactor equipped with submerged flat sheet membrane using the synthetic wastewater. The membrane system for the activated sludge solution of MLSS 5,000 mg/L was operated with constant permeate flux by continuously permeating and periodically 10 minute-permeating/2 minute-resting modes, respectively. The transmembrane pressure was measured as the permeate flux increased from 10 to $25L/m^2{\cdot}hr$ under the constant air flowrate 0.25 L/min. Also, the complete blocking, standard blocking, intermediate blocking, incompressible cake and linear compressible cake fouling models were retrofitted for the experimental data in order to determine the state of the membrane fouling. Because the transmembrane pressure fluctuated as a pulse shape for every period of 10 minute-permeating/2-minute resting mode, the membrane fouling models were separately applied for the maximum and minimum connecting lines. The linear compressible cake fouling model for the activated sludge cakes was the best fitted with the experimental results from the above five models.

• Membrane Journal
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• v.20 no.3
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• pp.241-248
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• 2010

The effect of organic material loadings on nutrient removal characteristics were investigated in sequencing batch reactor, in which a flat sheet type microfiltration membrane with a pore size of $0.4\;{\mu}m$ was submerged. Three organic concentrations of 200 mg/L (Run-1), 400 mg/L (Run-2) and 800 mg/L (Run-3) were carried out continuously to identify their effect on the filtration performance and nutrient removal. The removal efficiencies of T-N and T-P were increased with the increase of COD/N and COD/P. The T-N removal efficiencies of Run-1, Run-2 and Run-3 were 28.1, 32.6 and 90.4%, the average concentrations of T-N in permeate were 32.0, 30.0, and 4.3 mg/L, respectively. The T-P removal efficiencies of Run-1, Run-2 and Run-3 were 13.6, 35.3 and 93.1%, the average concentrations of T-P in permeate were 3.11, 2.33, and 0.25 mg/L, respectively.

• Transactions of Materials Processing
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• v.25 no.2
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• pp.116-123
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• 2016

Press-brake bending is used to shape flat and thick plates into a targeted circular configuration without excessive localized thinning or thickening. A brake bending press called 'a knife press bending apparatus' has been widely adopted to manufacture thick, large and long pipe from initially thick plate. Submerged Arc Welded (SAW) pipes are also produced by employing press-brake bending. These pipes are mainly used for oil, natural gas and water pipelines. The principal process variables for press-brake bending can be summarized as stroke of the press-brake knife, the distance between both roll in the lower die, and the feeding length of the plate. Many combinations of these process variables are available, thus various pipe diameters can be realized. In the current study, a series of repetitive numerical simulations by feeding a thick plate with initial thickness of 25.4mm were conducted with the consideration of elastic recovery. Furthermore, an index for SAW pipe production is proposed which can be widely used in industry.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.263-271
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• 2018

The objective of this work was to analyze organic matter removal, nitrification, biomass growth and membrane fouling in a submerged flat-sheet membrane bioreactor, fed with synthetic wastewater, of similar composition to the effluents generated in a fish meal industry. After biomass acclimatization with saline conditions of 12 gNaCl/L and COD/N ratio of 15 in the bioreactor, results showed that the organic matter removal was higher than 90%, for all organic loading rates (0.8, 1, 1.33 and $2gCOD/L{\cdot}d$) and nitrogen loading rates (0.053, 0.067, 0.089 and $0.133gN/L{\cdot}d$) tested during the study. However, nitrification was only carried out with the lowest OLR ($0.8gCOD/L{\cdot}d$) and NLR ($0.053gN/L{\cdot}d$). An excessive concentration of organic matter in the wastewater appears as a limiting factor to this process' operating conditions, where nitrification values of 65% were reached, including nitrogen assimilation to produce biomass. The analysis of membrane fouling showed that the bio-cake formation at the membrane surface is the most impacting mechanism responsible of this phenomenon and it was demonstrated that organic and nitrogen loading rates variations affected membrane fouling rate.

• Membrane Journal
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• v.21 no.3
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• pp.263-269
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• 2011

In the operation of submerged membrane-coupled sequencing batch reactor, the effect of filling step on the removal efficiency and filtration performance were investigated. Two sets of operation modes, the filling step located in the beginning of aerobic step (Mode-1) and the beginning of anoxic step (Mode-2), during 89 days were conducted. There was no wide difference in the COD removal and filtration performance between two sets of operation modes. But in the removal efficiency of nutrients (total nitrogen and total phosphorous), Mode-2 was more effective than Mode-1. In the case of Mode-2, average removal efficiencies of COD, total nitrogen, and total phosphorous were 99.1, 73.3, and 77.3%, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.7 s.238
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• pp.878-885
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• 2005

The water jet impingement cooling is one of the techniques to remove the heat from high heat flux equipments. Local heat transfer of the confined water impinging jet and the effect of nozzle collar to enhance the heat transfer are investigated in the fee surface jet and submerged jet. Boiling is initiated from the farthest downstream and increase of the wall temperature is reduced with developing boiling, forming the flat temperature distributions. The reduction in the nozzle-to-surface distance fur H/W$\le$1 causes significant increases and distribution changes of heat transfer. Developed boiling reduces the differences of heat transfer for various conditions. The nozzle collar is employed at the nozzle exit. The distances from heated surface to nozzle collar, Hc are 0.25W, 0.5W and 1.0W. The liquid film thickness is reduced and the velocity of wall jet increases as decreased spacing of collar to heated surface. Heat transfer is enhanced fur region from the stagnation to x/W$\~$8 in the free surface jet and to x/W$\~$5 in the submerged jet. For nucleate boiling region of further downstream, the heat transfer by the nozzle collar is decreased in submerged jet comparing with higher velocity condition. It is because the increased velocity by collar is de-accelerated downstream.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1452-1457
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• 2004

The water jet impingement cooling is one of the techniques to remove heat from high heat flux equipments. We investigate the local heat transfer of the confined water impinging jet and the effect of nozzle collar to enhance the heat transfer in the free surface jet and submerged jet. Boiling is initiated from the furthest downstream and the wall temperature increase is reduced with developing boiling, forming the flat temperature distributions. The reduction in the nozzle-to-surface distance for $H/W{\leq}1$ causes the significant increases and distribution changes in heat transfer. Developed boiling reduces the differences in heat transfer for various conditions. The nozzle collar is employed at the nozzle exit. The distances from heated surface to guide plate, $H_c$ are 0.25W, 0.5W and 1.0W. The liquid film thickness is reduced and the velocity of wall jet increase as decreased spacing of collar to heated surface. Heat transfer is enhanced for region from the stagnation to $x/W{\sim}8$ in the free surface jet and to $x/W{\sim}5$ in the submerged jet. For nucleate boiling region of further downstream, the heat transfer by the nozzle collar is decreased in submerged jet compare with higher velocity condition. It is because the increased velocity by collar is de-accelerated at downstream.