• Journal of the Korean GEO-environmental Society
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• v.10 no.1
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• pp.43-48
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• 2009

This study was performed to investigate the characteristics of nutrient removal by Sequencing Batch Reactor (SBR) system, which could achieve high removal efficiencies of nitrogen and phosphorus and make it possible convenient management and operation. In this study, dissolved oxygen (DO), chemical oxygen demand (COD), nitrogen, and phosphorus in SBR system were examined by variation of anoxic-oxic phase repetition in order to optimize an operational method. The 1~4 times of anoxic-oxic phases (Run 1~4) were repeated during 1 cycle operation period. As the repetition frequency increased, it was more difficult to maintain DO condition enough for denitrification. The SBR system showed high COD removal efficiency more than 91% regardless of operational condition. About 68% of nitrogen removal rate was obtained in conditions of 2 or 3 times repetition of anoxic phases, in which NOx-N among discharged total nitrogen account for more than 99%. Approximately 40% of phosphorus was eliminated in the conditions of 1~3 times of anoxic phase repetition.

• KSBB Journal
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• v.26 no.4
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• pp.311-316
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• 2011

We investigated the optimal surface aeration rate during bioethanol production from the hydrolysate of seaweed Sargassum sagamianum using Pichia stipitis. It was observed that, when the working volume was 880 mL in 2.5-L lab-fermentor, the surface aeration rates of 30 to 100 mL/min were the optimal values for bioethanol production, in which this surface aeration rate corresponded to less than 0.05 (1/min) as the oxygen transfer rate coefficient ($k_La$). In addition, during repeated-batch operation was carried out, we examined whether those surface aeration rates were the optimal for bioethanol production. It was also observed that the surface aeration rates of 30 to 100 mL/min in the working volume of 880 mL were the optimal values in terms of the cumulative bioethanol producrion and bioethanol yield. On the basis of the oxygen transfer rate coefficient it is probable that those surface aeration rates will be applied to the large-scale bioethanol production from the hydrolysate of seaweed Sargassum sagamianum.

• Fisheries and Aquatic Sciences
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• v.14 no.3
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• pp.230-233
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• 2011

To determine the cost-effectiveness of converting fish waste into liquid fertilizer, this study analyzed the production of 3 L of liquid fertilizer from the fermentation of fish waste. The total product cost of the fertilizer was calculated to be $165.26 for a one-batch operation. If the seed culture was repeated five times, the total product cost could be reduced to $36.39/L. According to this analysis, the reutilization of fish waste as liquid fertilizer was not particularly economically attractive at present, and plant-scale production would be necessary for commercialization. This is the first cost-effectiveness analysis of the bioconversion of fish waste into liquid fertilizer.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.1
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• pp.96-104
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• 2013

Study of human-robot Interaction gets more and more attention to expand the robot application for tasks difficult by robot alone. Developed countries are preparing for a new market by introducing the concept of 'Co-Robot' model of human-robot Interaction. Our research of direct teaching is a way to instruct robot's trajectory by human's handling of its end device. This method is more intuitive than other existing methods. The benefit of this approach includes easy and fast teaching even by non-professional workers. And it can enhance utilization of robots in small and medium-sized enterprises for small quantity batch production. In this study, we developed the algorithms for creating accurate trajectory from repeated inaccurate direct teaching and GUI for the direct teaching. We also propose the basic framework for direct teaching.

• KSBB Journal
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• v.14 no.2
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• pp.230-234
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• 1999

To improve the crossflow untrafiltration flux, we applied periodic oscillations in transmembrane pressure gradient in order to promote fluid turbulence by inducing repeated compression and relaxation of the cake/gel layer. The oscillatory forms used were square-, sine-, triangle-wave, and pumping interruption. The permeate flux profiles were mathematically simulated and compared with the experimental data. The result showed the periodic pumping interruption most effectively improved the overall flux by up to about 32%. Enough pumping off-time, at least on the order of tens of seconds, was needed to allow the solutes in the layer to diffuse back to the bulk phase. It was better to start the oscillations earlier before the layer was fully established. The square-wave oscillation yielded about 11% increase, which was particularly pronounced in the later part of the filtration. Either the amplitude or the period of the oscillations resulted little influence on flux.actate ester, and lactate ester produced in esterification reaction was distilled simultaneously with hydrolysis reaction into lactic acid. When the yields of lactic acid recovered by batch reactive distillations with various alcohols were compared, the yield of lactic acid was increased as the volatility of lactate ester was increased. In this batch reactive distillation, because the mixtures condensed in partial condensor were flown to reboiler through distillation column, the recovery yield of lactic acid was affected by operation temperature of partial condensor. Hydrolysis reaction into lactic acid in distillation column rarelyoccurred because of short retention time of lactate ester and water. Lactate ester was reacted into lactic acid in reboiler.

• Journal of Radiation Protection and Research
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• v.24 no.2
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• pp.73-86
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• 1999

The ion-exchange method for the purification of primary coolant has been used broadly in PWR(pressurized water reactor)-type nuclear power plants due to its high decontamination efficiency, simple system, and easy operation. However, its non-selective removal of metal and non-radionuclides shortens its life, resulting in the generation of a large amount of waste ion-exchange resin. In this study, the feasibility of electrodeionization (EDI) was investigated for the purification of primary cooling water using synthetic solutions under various experimental conditions as an alternative method for the ion exchange. The results shows that as the feed flow-rate increased, the removal efficiency increased and the power consumption decreased. The removal rate was observed as a 1000 decontamination factor(DF) at a nearly constant level. For the synthetic solution of 3 ppm TDS (Total Dissolved Solid), the power consumption was 40.3 mWh/L at 2.0 L/min of feed flow rate. The higher removal rate of metal species and lower power consumption were obtained with greater resin volume per diluting compartment. However, the flow rate of the EDI process decreased with the elapsed time because of the hydrodynamic resistivity of resin itself and resin fouling by suspended solids. Thus, the ion-exchange resin was replaced by an ion-conducting spacer in order to overcome the drawback. The system equipped with the ion-conducting spacer resolved the problem of the decreasing flow rate but showed a lower efficiency in terms of the power consumption, the removal rate of metal species and current efficiency. In the repeated batch operation, it was found that the removal efficiency of metal species was stably maintained at DF 1000.