• Journal of the Korean Society for Heat Treatment
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• v.18 no.6
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• pp.375-382
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• 2005

This paper presents the results of experimental investigation for the effect of heat conduction on the evaporation cooling of water droplet in the process of heat treatment. The experiments are mainly focused on the surface temperature, the surface roughness and the droplet diameter at aluminum. The range of surface temperature is from $80^{\circ}C$ to $140^{\circ}C$, surface roughness is from $R_a=0.18{\mu}m$ to $R_a=1.36{\mu}m$ and droplet diameter is from 2.4 mm to 3.0 mm. The results show that the total evaporation time is shorter for the larger surface roughness, the time averaged heat flux has maximum value for the larger surface roughness and exist the critical heat flux. The total evaporation time has a big influence on the evaporation region for the smaller droplet size, but the total evaporation time has not influence on the nuclear boiling region.

• Resources Recycling
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• v.29 no.1
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• pp.70-80
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• 2020

This study investigates the effect of flux type and mixing ratio on efficiency in aluminum can scrap recycling using induction furnace. The removal of surface coating layer of aluminum can scrap was possible through heat treatment at about 500 ℃ for about 30 min. The temperature for the melting process was set to be slightly above the melting temperature of the aluminium can scrap. The molten metal treatment was performed with different types of flux and mixing ratio. As a result, The optimum efficiency of Al recovery ratio was revealed when the process was performed with at least 3 wt.% of the flux (Salt and MgCl₂ mixture of ratio 70:30) at 750 ℃. The mechanical property of the recovered Al alloy showed that the tensile strength is about 249 MPa and elongation is about 14 %. This result was found to be similar to the mechanical property of the virgin Al 5083 alloy.

• Asian Journal of Atmospheric Environment
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• v.4 no.1
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• pp.33-41
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• 2010

Because ammonia from livestock production may substantially contribute to environmental pollution, emissions from all possible sources (housing systems, manure storage, manure application, outside grazing) should be reduced. The purpose of this study was to investigate the effect of different bedding materials on ammonia emissions in a cow house. By applying a combination of four treatment types: treatment $1-T_1$ (sawdust (50%)+sawdust pellets (50%)), treatment $2-T_2$ (sawdust (50%)+corn stalk pellets (50%)), treatment $3-T_3$ (sawdust (100%)), and treatment $4-T_4$ (sawdust (50%)+palm kernel meal pellets(50%)) as bedding materials in a cow house, the effects of such treatments on ammonia flux were assessed in approximately one month. The magnitude of ammonia emissions (mg $m^{-2}\;min^{-1}$) varied in the following order: $T_1$(2.226), $T_4$(2.052), $T_2$(1.845), and $T_3$(1.712). The patterns of pH had a decreasing trend for all bedding treatments during the experiment, and there was no significant relationship with ammonia flux. The results reveal that the most important factor influencing ammonia emissions is the physical structure of the bedding types.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.285-292
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• 2018

In the following study, Artificial Neural Network (ANN) is used for prediction of permeate flux decline during oily wastewater treatment by hybrid powdered activated carbon-microfiltration (PAC-MF) process using mullite and mullite-alumina ceramic membranes. Permeate flux is predicted as a function of time and PAC concentration. To optimize the networks performance, different transfer functions and different initial weights and biases have been tested. Totally, more than 850,000 different networks are tested for both membranes. The results showed that 10:6 and 9:20 neural networks work best for mullite and mullite-alumina ceramic membranes in PAC-MF process, respectively. These networks provide low mean squared error and high linearity between target and predicted data (high $R^2$ value). Finally, the results present that ANN provide best results ($R^2$ value equal to 0.99999) for prediction of permeation flux decline during oily wastewater treatment in PAC-MF process by ceramic membranes.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.3
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• pp.155-163
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• 2017

Membrane filtration has become more popular in drinking water treatment recently, since the filtration can control not only particulate matters but also pathogenic microorganisms such as giardia and cryptosporidium very effectively. Pilot-scale ($120m^3/d$ of treatment capacity) and test-bed ($25,000m^3/d$ of treatment capacity) microfiltration experiments were conducted to find optimum operating mode and the critical flux. Optimum operating mode of pilot-test was assessed as inflow 1.0 min, filtration 36.5 min, air backwash 0.9 min, backwash 1.0 min and outflow 1.0 min with 50 LMH ($L/min{\cdot}m3^$) of critical flux. Critical Flux was calculated to be $50L/m^2-h$ (within TMP 0.5 bar) based on the increase formula of the transmembrane pressure difference according to the change of time at Flux 20, 40, 56 and 62 LMH in pilot operation. Chemical cleaning was first acid washed twice, and alkali washing was performed secondarily, and a recovery rate of 95% was obtained in the test-bed plant. The results of operating under these appropriate conditions are as follows. Turbidity of treated water were 0.028, 0.024, 0.026 and 0.028 NTU in spring, summer, autumn and winter time, respectively. Microfiltration has superior treatment capability and performance characteristics in removing suspended solids and colloidal materials, which are the main cause of turbidity and important carrier of metal elements, and it has shown great potential in being an economically substitute to traditional processes (sand filtration).

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.704-709
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• 2021

In the flux used in the batch galvanizing process, the effect of the component ratio of NH₄Cl to ZnCl₂ on the microstructure, coating adhesion, and corrosion resistance of Zn-Mg-Al ternary alloy-coated steel is evaluated. Many defects such as cracks and bare spots are formed inside the Zn-Mg-Al coating layer during treatment with the flux composition generally used for Zn coating. Deterioration of the coating property is due to the formation of AlCl_x mixture generated by the reaction of Al element and chloride in the flux. The coatability of the Zn-Mg-Al alloy coating is improved by increasing the content of ZnCl₂ in the flux to reduce the amount of chlorine reacting with Al while maintaining the flux effect and the coating adhesion is improved as the component ratio of NH₄Cl to ZnCl₂ decreases. Zn-Mg-Al alloy-coated steel products treated with the optimized flux composition of NH₄Cl·3ZnCl₂ show superior corrosion resistance compared to Zn-coated steel products, even with a coating weight of 60 %.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.1
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• pp.47-53
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• 2018

This study investigated phosphorus removal from secondary treated effluent using coagulation-membrane separation hybrid treatment to satisfy strict regulation in wastewater treatment. The membrane separation process was used to remove suspended phosphorus particles after coagulation/settlement. Membrane separation with $0.2{\mu}m$ pore size of micro filtration membrane could reduce phosphorus concentration to 0.02 mg P/L after coagulation with 1 mg Al/L dose of polyaluminum chloride (PACl). Regardless of coagulant, the residual concentration of phosphorus decreased as the dose increased from 1.5 to 3.5 mg Al/L, while the target concentration of 0.05 mg P/L or less was achieved at 2.5 mg Al/L for the aluminum sulfate (Alum) and 3.5 mg Al/L for PACl. Moreover, alum showed better membrane flux as make bigger particles than PACl. Alum showed a 40% of flux decrease at 2.5 mg Al/L dose, while PACl indicated a 50% decrease of membrane flux even with a higher dose of 3.5 mg Al/L. Thus, alum was more effective coagulant than PACl considering phosphorus removal and membrane flux as well as its dose. Consequently, the coagulation-membrane separation hybrid treatment could be mitigate regulation on phosphorus removal as unsettleable phosphorus particles were effectively removed by membrane after coagulation.

• Membrane and Water Treatment
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• v.1 no.1
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• pp.83-92
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• 2010

To improve the antifouling characteristics of polypropylene hollow fiber microporous membranes in a submerged membrane-bioreactor for wastewater treatment, the surface-modification was conducted by Ar plasma treatment. Surface hydrophilicity was assessed by water contact angle measurements. The advancing and receding water contact angles reduced after the surface modification, and hysteresis between the advancing and receding water contact angles was enlarged after Ar plasma treatment due to the increased surface roughness after surface plasma treatment. After continuous operation in a submerged membrane-bioreactor for about 55 h, the flux recovery after water cleaning and the flux ratio after fouling were improved by 20.0 and 143.0%, while the reduction of flux was reduced by 28.6% for the surface modified membrane after 1 min Ar plasma treatment, compared to those of the unmodified membrane. Morphological observations showed that the mean membrane pore size after Ar plasma treatment reduced as a result of the deposition of the etched species; after it was used in the submerged membrane-bioreactor, the further decline of the mean membrane pore size was caused by the deposition of foulants. X-ray photoelectron spectroscopy and infrared spectroscopy confirmed that proteins and polysaccharide-like substances were the main foulants in the precipitate.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.175-180
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• 2001

In this study, the minimum heat flux conditions are experimentally investigated for the spray cooling of hot plate. The hot plates are cooled down from the initial temperature of about $900^{\circ}C$, and the local heat flux and surface temperatures are calculated from the measured temperature-time history. The results show that the minimum heat flux point temperatures increase linearly resulting from the propagation of wetting front with the increase of the distance from the stagnation point of spray flow. However, in the wall region, the minimum heat flux point temperature becomes independent of the distance. Also, the experimental results show that the velocity of wetting front increases with the increase of the droplet flow rate.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.92-97
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• 2007

This study aims at investigating the wear behavior of thermally sprayed Ni-based self-flux alloy coatings against different counterparts. Ni-based self-flux alloy powders were flame-sprayed onto a carbon steel substrate and then heat-treated at temperature of $1000^{\circ}C$. Dry sliding wear tests were performed using the sliding speeds of 0.2 and 0.8 m/s and the applied loads of 5 and 20 N. AISI 52100, $Al_2O_3$, $Si_3N_4$ and $ZrO_2$ balls were used as counterpart materials. Wear behavior of Ni-based self-flux alloy coatings against different counterparts were studied using a scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy (EDX). It was revealed that wear behavior of Ni-based self-flux alloy coatings were much influenced by counterpart materials.