• KSBB Journal
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• v.24 no.4
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• pp.353-360
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• 2009

This study was accomplished using Anaerobic/Anoxic/Oxic upflow packed-bed column reactors with fixed media and Loop Reactor with fluidized media instead of Oxic reactor. The objectives of this study was to investigate the characteristics of organics, nitrogen and phosphorus removal from sewage with the HRT. The average removal efficiencies of $BOD_5$ and SS increase as increasing the hydraulic retention time (HRT) until 16 h of the HRT, and they were constant over 16 h of the HRT. The removal efficiency of $BOD_5$ in case of packed-bed reactor and Loop Reactor was about 86.6% and 90.9% respectively at 16 h of the HRT. The removal efficiency of SS in packed-bed reactor and Loop Reactor was about 78.0% and 88.2% respectively at 16 h of the HRT. The average removal efficiencies of $COD_{Cr}$ and $COD_{Mn}$ showed similar trends as those of $BOD_5$ and SS. At the HRT of 16 h, the removal efficiency of $COD_{Cr}$ in case of packed-bed reactor and Loop Reactor was 63.5%, 75.2% and that of $COD_{Mn}$ was 60.7%, 73.6% respectively. The average removal efficiencies of T-N and T-P increase as increasing the HRT. The removal efficiencies of T-N and T-P in Loop Reactor were 33.6% and 54.5% respectively at 16 h of the HRT and T-N and T-P were better removed in Loop Reactor. From this result, it was found that the performance of Loop Reactor was much higher than the performance of packed-bed reactor and the optimum HRT was 16 h.

• Journal of Biomedical Engineering Research
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• v.3 no.1
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• pp.9-16
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• 1982

Removal of urea and vitamin B12 was simulated using two pool models with closed loop dialysis, open loop dialysis, and hemodiafiltrations with predilution and postdilulion. It was found that urea removal was limited by dialyzer clearance, however B12 removal was limited both by the resistance between ECF and ICF and by dialyzer clearance. Open loop dialysis was better than closed loop dialysis in terms of dialysate requirement and removal efficiency. Residual renal function plays an important role in removing vitamin B12. Dialysis frequency more than twice/wide does not have great effect on removal efficiency, but has the effect of reducing the difference between maximum and minimum cancentrations during dialysis period.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.4
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• pp.381-386
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• 1997

The offsetting method using geometric properties of B-spline control polygon is more faster than using of general normal vector in offset processing. But this method itself does not solve the prob¬lems of loop removal in normal offsetting. Generally the distance between neighborhood spans of B-spline control polygon is greater than the offset distance, the loops are occurred in offsetting. For generating of the more precision tool-path in NC machining, the loops of offset must be removed. In this paper, two methods for loop removal are introduced in offsetting of B-spline curve. One is using the intersection of B-spline control span which being occurred of the loop. The other is using two B-spline curve divisions divided from original B-spline curve or its offset curve. After the inter¬section point of loop was searched, the loop being removed to cusp. Also the method for filleting of cusp is inspected to more precision cutting. It is shown that the offsetting using B-spline control polygon is more effective in the sculptured surface machining.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.4
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• pp.361-367
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• 2016

Pollutants removal and disinfection effect of secondary effluent from final settling tank of sewage treatment plant of W city were investigated in Loop Reactor using ordinary granular activated carbon(GAC) and GAC coated with silver nanoparticles. The results showed that the removal efficiency of $COD_{Mn}$, T-N and T-P using GAC with silver nanoparticles were higher than using the ordinary GAC. The removal efficiency of T-P using GAC with silver nanoparticles is 45.4% and that of T-P using ordinary GAC is 30.9% in the same case of the input amount of 20 g/L of GAC. The total califorms is reduced according to increasing input amount of GAC with silver nanoparticles and ordinary GAC. The disinfection efficiency of total coliforms in case of GAC with silver nanoparticles is much higher than that in case of ordinary GAC. For all experiments using the silver nanoparticles, the total coliforms is under 26 cfu/mL and this shows very excellent disinfection effect.

• Journal of Korea Multimedia Society
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• v.9 no.12
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• pp.1700-1708
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• 2006

Since the most program execution time is consumed in a loop structure, extracting parallelism from loop programs is critical for the taster program execution. In this paper, we proposed data dependency removal method for a single loop. The data dependency removal method can be applied to uniform and non-uniform data dependency distance in the single loop. Procedure calls parallelisms with only a single loop structure or procedure call most of other methods are concerned with the uniform code within the uniform data dependency distance. We also propose an algorithm, which can be applied to uniform, non-uniform, and complex data dependency distance among the multiple procedures. We compared our method with conventional methods using CRAY-T3E for the performance evaluation. The results show that the proposed algorithm is effective.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.101-107
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• 2016

This paper investigates the feasibility of applying the jet loop reactor for the neutralization of alkaline wastewater using carbon dioxide ($CO_2$). In this study, pH changes and $CO_2$ removal characteristics were examined by changing influent flow rate of alkaline wastewater (initial pH=10.1) and influent $CO_2$ flow rates. Influent flow rates of alkaline wastewater ($Q_{L,in}$) ranged between 0.9 and 6.6 L/min, and inlet gas flow rate ($Q_{G,in}$) of 1 and 6 L/min in a lab-scale continuous flow jet loop reactor. The outlet pH of wastewater was maintained at 7.2 when the ratio ($Q_{L,in}/Q_{G,in}$) of $Q_{L,in}$ and $Q_{G,in}$ was 1.1. However, the $CO_2$ removal efficiency and the outlet pH of wastewater were increased when $Q_{L,in}/Q_{G,in}$ ratio was higher than 1.1. Throughout the experiments, the maximum $CO_2$ removal efficiency and the outlet pH of wastewater were 98.06% and 8.43 at the condition when $Q_{G,in}$ and $Q_{L,in}$ were 2 L/min and 4 L/min, respectively.

• KSBB Journal
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• v.17 no.3
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• pp.241-246
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• 2002

Today, many problems of dye-processing wastewaters were raised due to industry of dyeing and textiles. It is difficult to treat them perfectly because they contain many poorly degradable matters, such as surfactants, ethylene glycol, polyvinyl alcohol, and so on. To improve the performances of conventional physicochemical treatment and activated sludge process, new systems of combining jet-loop reactor (JLR) with physicochemical treatment were developed. Volumetric oxygen transfer coefficient ($k_{L}a$) of JLR was significantly larger than that of air-lift reactor. Also, for the effective treatment of dye-processing wastewater, JLR with active carbon supports (JLRAS) were investigated. Removal efficiency of BOD, $COD_{Mn}$, $COD_{Cr} and color were found as 99, 86, 84, 83%, respectively, when HRT was 8 hrs. And performance of JLRAS was rapidly restored after step change of $COD_{Mn}$ loading late. The optimal coagulant and dosage of second physicochemical treatment after JLRAS were polyferric sulfate and 130 mg/L, respectively, when removal efficiencies of $COD_{Mn} and color were 85 and 73%, respectively. In conclusion, this system enables the reduction of operation cost, and the effective removal of many organics.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2499-2508
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• 2021

Passive containment cooling systems (PCCSs) have been actively studied to improve the inherent safety of nuclear power plants. Hered, we present two concepts, open-loop PCCS (OL-PCCS) and closed-loop PCCS (CL-PCCS), applicable to the PWR with a concrete-type containment. We analyzed the heat-removal performance and flow instability of these PCCS concepts using the GOTHIC code. In both cases, PCCS performance improved when a passive containment cooling heat exchanger (PCCX) was installed in the lower part of the containment building. The OL-PCCS was found to be superior in terms of heat-removal performance. However, in terms of flow instability, the OL-PCCS was more vulnerable than the CL-PCCS. In particular, the possibility of flow instability was higher when the PCCX was installed in the upper part of the containment. Therefore, the installation location of the OL-PCCS should be restricted to minimize flow instability. Conversely, a CL-PCCS can be installed without any positional restriction by adjusting the initial system pressure within the loop, which eliminates flow instability. These results could be used as base data for the thermo-hydraulic evaluation of PCCS in PWR with a large dry concrete-type containment.

• KSBB Journal
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• v.14 no.1
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• pp.119-123
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• 1999

A jet-loop reactor was used for the biological treatment of ethylene glycol(EG) which is a main component of polyester weight-loss wastewater, and is difficult to be removed by physicochemical treatments. Volumetric oxygen coefficient(kLa) of jet-loop reactor was significantly larfgeer that of air-lift reactor. When organic loading rates of synthetic polyester weight-loss wastewater were 2.64 $kgOD_{Mn}/m^3$.day and 3.07 $kgCOD_{Cr}/m^3$.day, the effluent concentrations were measured as 154 $mgCOD_{Mn}/L$ and 156$mgCOD_{Cr}/L$, and removal efficiencies were found as 93%and 93.6%, respectively. The specific removal rate was proportionally increased from 0.25 to 1.60 $kgCOD_{Mn}$-removed/kgMLVSS.day as specific loading rate was increased from 0.25 to 1.72 $kgCOD_{Mn}$/kgMLVSS.day. Also, kinetics constants such as $K_s$, k, $K_d$, and Y were estimated as 89 mg/L, $0.05 hr^{-1}$, 0.1$day^{-1}$ and 0.78 respectively. When the organic loading rates of real polyester weight-loss wastewater were 2.64 $kgOD_{Mn}/m^3$. and 5.24 $kgCOD_{Cr}/m^3$. day, the effluent concentrations were measured as 150 $mgCOD_{Mn}$/L, and 306 $mgCOD_{Cr}$/L, and removal efficiencies were found as 93.2% and 93%, respectively. This study demonstrated that EG in the wastewater could be efficiently removed biologically using a jet-loop reactor.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.8
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• pp.603-610
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• 2009

This research was performed to improve removal efficiency of toluene and methyl ethyl ketone (MEK) using Candida tropicalis, one of the yeast species. An airlift loop bioreactor (ALB) was employed to enhance the capability of mass transfer for toluene and MEK from the gas phase to the liquid, microbial phase. Polymer gel media made from PAC, alginate and PEG was applied for the effective immobilization of the yeast strain on the polymer gel media. The experimental results indicated that the mass transfer coefficient of toluene without polymer gel media was 1.29 $min^{-1}$ at a gas retention time of 15 sec, whereas the KLa value for toluene was increased to 4.07 $min^{-1}$ by adding the media, confirming the enhanced mass transfer of volatile organic compounds between the gas and liquid phases. The removal efficiency of toluene and MEK by using yeast-immobilized polymer gel media in the ALB was greater than 80% at different pollutant loading rates (5, 10, 19 and 37 g/$m^3$/hr for toluene, 4.5, 8.9, 17.8 and 35.1 g/$m^3$/hr for MEK). In addition, an elimination capacity test conducted by changing inlet loading rates stepwise demonstrated that maximum elimination capacities for toluene and MEK were 70.4 and 56.4 g/$m^3$/hr, respectively.