• Resources Recycling
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• v.14 no.2
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• pp.28-32
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• 2005

By using thermal decomposition method, the preliminary experiments for recovery of metallic Ga from GaAs scraps produced in the manufacturing of compound semiconductors were carried out in laboratory(200 g/batch) scales. From these results, decomposition appratus with packed tower was constructed in commercial scale(30 kg/batch). The decomposition rate of GaAs increased with raising decomposition temperature, but the yield of Ga decreased over 1000$^{\circ}C. As a result, the optimum decomposition temperature was 1000~1050$^{\circ}C when the pressure of decomposition reactor was 2~2.5${\times}10^{-2} mmHg, and the yield of Ga was about 89 wt.%. The commercial decomposition apparatus was designed with packed tower because the partial pressure of As in vapor state was not reduced even if the temperature of As vapor was decreased. The recovery yield of Ga from GaAs scraps in large scale experiment showed 99%.

• Journal of Environmental Science International
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• v.10 no.4
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• pp.281-286
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• 2001

Wastewater from the pigment industry has high levels of organics and is known as hardly biodegradable. The objective of this study is to evaluate the applicability of aerobic fixed-bed boifilm reactor packed with ceramic support carrier for the pigment wastewater treatment. Orange 2(widely used azo pigment) adsorption experiment onto biofilm and activated sludge, and continuous treatment experiments were performed. In batch adsorption experiment, maximum adsorption quantity of biofilm was at least two times higher than that of activated sludge. In continuous experiment using aerobic fixed-bed biodilm reactor, the influent concentration of COD and Orange 2 were 75~500mg/${\ell}$(0.45~3.00kg COD/$m^3.day), 5~50mg/$\ell$(0.03~0.30kg Orange 2/$m^3$.day), respectively. At a COD loading rate 2.5kg COD/$m^3$.day and Orange 2 loading rate of 0.18kg Orange 2/$m^3$.day, removal efficiency of COD and Orange 2 were over 95%, 97%, respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.327-335
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• 1999

A batch process in which transfer bars are rolled in single bar units involves many problems in terms of quality, yield and threading stability. The endless rolling process is an effective solution to such problems. In this, study, an analysis model is proposed to calculate the distribution of normal stress in endless rolling process. The model was examined by comparing with the result of experiment. A device using the spring is developed for improving the welding quality.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.2
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• pp.124-129
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• 1991

A mass balance method which measures directly both the sorbed pesticide and equilibrium solution concentration was compared with the batch method in a hypothetical experiment to determine the precision of sorption measurement. The mass balance method was shown to improve precision of sorption measurement. The two methods were also tested experimentally on the Wahiawa soil, 0-20, 40-60 and 100-120 cm, and Salinas soil, 0-15 and 115-130 cm. The mass balance method greatly improved precision of sorption measurement on the deep Wahiawa subsoil having the lowest sorption. The coefficient of variation (CV) for $K_d$ measurement was 20.3% for the batch method and 8.4% for the mass balance method. For other soil samples tested, precision of the batch method was relatively high but was still improved by the mass balance method.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1126-1126
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• 2001

The paper presented here is the initial part of a larger study, in which it was determined which quality parameters in cheese powder could already be predicted by NIR at an early stage in the process and which could only be predicted at the final stages of the process. This initial study was performed in order to establish the levels and nature of variation within and between batches such that the subsequent data collection could be tackled optimally. The perspectives evolved into more than was originally planned and revealed some interesting uses of NIR-technology. Cheese powder production starts as a batch process, where waste cheese from other dairies is melted down in a vat. The process then turns into a continual process as the vat is emptied and the melted cheese is then filtered, homogenized, pasteurized and finally spray dried. Between each batch the powder is to a greater or lesser degree a mixture of 2 batches. This paper is divided into 2 aspects, one regarding the optimization of sampling time and the other is a study of process dynamics. Optimizing sampling time This initial study included 9 powder samples from 9 different batches produced during one day. The raw materials for the batches were chosen with the aim of creating a relatively high level of variation in the data. The total of 81 samples were taken out at regular intervals and spectra were collected on a NIR-systems 6500 instrument. The subsequent reduction of the data by PCA to score values shows the power of NIR as a tool to determine not only when samples are representative of a certain batch, but also which batches are stable enough to include in a further study. Studying process dynamics To take this experiment a step further 1 of the 81 samples were sent to the laboratory for further analyses. The samples were chosen on the criteria that they covered the spectral variation in the dataset. These samples were analysed for 4 chemical components and 5 physical attributes, which are essential for describing the quality of the product. The latent structure of the 7 samples, using the chemical and physical variables, is totally comparable to the latent structure of the NIR spectra. This outcome makes it possible to describe the dynamics of one day's production both chemically and physically with relatively little resources. Additionally it raises the question as to whether reference values are needed, as the latent structure of the NIR-spectra appears to be sufficient in providing information on the quality of the product. To be able to use NIR in this way would require defining quality limits in the principal component space as opposed to each of the reference values. The potential of NIR applied in an explorative fashion with batch processes opens a whole new gateway for the use of this technology. This study explains yet again after so many years in the field “why I'm crazy about NIR!”.

• Journal of Environmental Science International
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• v.25 no.9
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• pp.1233-1239
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• 2016

This study aimed to evaluate changes in the TN and TP removal efficiencies, depending on whether or not a settling process is applied, in a sequencing batch reactor (SBR) process with a membrane bioreactor (MBR). Nutrient removal was considered in terms of developing an advanced water treatment system for ships in accordance with water quality standards set forth by 227(64). For these purposes, the TN and TP concentrations in the inflow and outflow water were measured to calculate the TN and TP removal efficiencies, depending on whether or not a settling process was used. Water discharged from a bathroom, which was constructed for the experiment, was used as the raw water. The experiment that included a settling process was conducted twice, and the operating conditions were: aeration for 90 min, settling for 30 min, agitation for 15 min, and settling for 15 min for one experiment; and aeration for 150 min, settling for 45 min, agitation for 15 min, and settling for 15 min in the other. Operating conditions for the experiment that did not include a settling process were: aeration for 180 min and agitation for 60 min. The concentration of the mixed liquor suspended solids (MLSS) in the reactor was 3,500 mg/L, while the aeration rate was 121 L/min and the water production rate was 1.5 L/min. For the two experiments where a settling process was applied, the average TN removal efficiencies were 44.39% and 41.05%, and the average TP removal efficiencies were 47.85% and 46.04%. For the experiment in which a settling process was not applied, the average TN removal efficiency was 65.51%, and the average TP removal efficiency was 52.51%. Although the final nutrient levels did not satisfy the water quality standards of MEPC 227(64), the TN and TP removal efficiencies were higher when a settling process was not applied.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.429-437
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• 2007

This study aims to develop a sulfur-using denitrification process which is possible a renovation to advanced treatment plant submerging a simple module in activated sludge aeration tank. At first, the impact factor of sulfur-using denitrification was appreciated by the batch test. Secondly, reflecting a dissolved oxygen effect of sulfur-using denitrification that was confirmed by the batch test, in a continuous nitrification/sulfur-using denitrification, high-rate nitrogen removal reaction was induced at optimum condition controlling DO concentration according to phases. Also, inside and outside of sulfur-using denitrification module was covered with microfilter and the module was considered as an alternative of clarifier. Result of batch test for sulfur-using denitrification, $NO_2{^-}N$ was lower for consumption of alkalinity and sulfur than that of $NO_3{^-}-N$. These results revealed the accordance of theoretical prediction. In continuous nitrification/sulfur-using denitrification experiment, actual wastewater was used as a influent, and influent nitrogen loading rates were increased 0.04, 0.07, 0.11, $0.14kg\;N/m^3-day$ by changing hydraulic retention times. At this time, nitrogen loading rates of packed sulfur were increased 0.23, 0.46, 0.69, $0.93kg\;N/m^3-day$. As a result, nitrification efficiency was about 100% and denitrification efficiency was 93, 81, 79, 72%. Accordingly, nitrogen removal was a high-rate. Also the module of sulfur-using denitrification covered with microfilter did not make a fouling phenomena according to increased flux. And the module was achieved effluent suspended solids of below 10 mg/L without a clarifier. In conclusion, it is possible a renovation to advanced treatment plant submerging a simple module packed sulfur in activated sludge aeration tank of traditional facilities. And the plant used the module packed sulfur is expected as a effective facilities of high-rate and the smallest.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.2
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• pp.113-122
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• 2007

In this study, uranium migration experiments have been performed using a natural groundwater and a granite core with natural fractures in a glove-box constructed to simulate an appropriate subsurface environment. Groundwater flow experiments using the non-sorbing anionic tracer Br were carried out to analyze the flow properties of groundwater through the fracture of the granite core. The result of the uranium migration experiment showed a breakthrough curve similar to that of the non-sorting Br. This result may imply that uranium migrates as anionic complexes through the rock fracture since uranium can form carbonate complexes at a given groundwater condition. The distribution coefficient $K_d$ of the uranium between the groundwater and the fracture filling material was obtained as low as 2.7 mL/g from a batch sorption experiment. This result agrees well with the result from the migration experiment, showing a faster elution of the uranium through the rock fracture. In order to analyze retardation properties of the uranium through the rock fracture, the retardation factor $R_d({\sim}16.2)$ was obtained by using the $K_d$ obtained from the batch sorption experiment and it was compared with the $R_d({\sim}14.3)$ obtained by using the result from the uranium migration experiment. The values obtained from the both experiments were very similar to each other. This reveals that the retardation of the uranium is mainly occurred by the fracture filling material when the uranium migrates through the fracture of a granite core.

• KSBB Journal
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• v.19 no.3
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• pp.236-240
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• 2004

Korean wastewaters have higher nitrogen concentrations than typical wastewaters of other countries. Most treatment processes such as activated sludge processes will need to supplement extra carbon sources for a complete removal of remaining nitrogen after the initial wastewater treatment, Because of these difficult matters, we have searched wastewater treatment methods that require no additional carbon sources. Wastewater treatment by microalgae in photobioreactors, using a green eukaryotic microalgae, Chlorella kessleri, showed a promising results and thus was selected to study further. This system is not intended to replace the conventional system but is to assist the existing biological treatment systems as a supplemental nitrogen removal process. Thus the secondary treated livestock wastewater was tested. Column type photobioreactors developed in our laboratory were used. When aerated with 5% CO$_2$ balanced with air at 1 vvm and illuminated at 100 ${\mu}$mol/㎡/s under 25$^{\circ}C$ and PH 7-8 by CO$_2$ buffering effect, the maximum nitrogen removal rate was 2.6 mg/L/hr. The results confirmed a possibility of microalgal wastewater treatment system as a secondary system to remove extra nitrogen sources. Based on these experimental results, the size of the optimal microalgal wastewater system was calculated. For the wastewater whose initial nitrogen concentration of 150 mg/L, the optimal batch system was found to be a 2 stage system with a combined retention time of 4.6 day. From the continuous experiments, nitrogen removal rates were examined under different dilution rates and 2 stage system was also found to be the optimal system. The combined retention time for the continuous system was 3.5 days. It is expected that conventional biological wastewater treatment systems followed by microalgal systems would reliably decrease the nitrogen concentration below the government criteria even for the livestock wastewater with low C/N ratio.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.687-694
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• 2005

Lab-scale experiments have been carried out to investigate the effect of F/R ratio of ASBR (Anaerobic Sequencing Batch Reactor) process on the removal of the organic matters in ammonia stripped swine wastewater. Three ASBR inoculated with sludge mixed with granular sludge of UASB (Upflow Anaerobic Sludge Blanket) and anaerobic digested sludge of municipal wastewater treatment plant were operated. Ammonia stripped swine wastewater was used as influent. Prior to conducting the experiments with varied conditions, the effect of increasing organic loading rate from 2.34 to $5.79gTCOD_{Cr}/L$-day at a fixed F/R ratio of 0.1 on the organic removal efficiency has been studied during start-up period. As the result of the experiment, under the condition of varied organic loadings, less than $4.14gTCOD_{Cr}/L$-day, the removed efficiency $TCOD_{Cr}$ of the ASBR process is 83% resulted from the mean value of effluent $TCOD_{Cr}$, 9,125 mg/L during the start-up period. Then ASBRs were operated with F/R ratio of 0.024, 0.303 and 0.91 respectively. Organic loading rate was increased from 4.56 to $15.43gTCOD_{Cr}/L$-day to investigate the effects of F/R ratio and organic loading rate on the organic removal efficiency. As the result of the experiment, less than $6.23gTCOD_{Cr}/L$/L-day, F/R ratio haven't an effect on the organic removal efficiency and the mean removal efficiency of TSS, $TCOD_{Cr}$ and $SCOD_{Cr}$ was about 80%, 86% and 78% at the all of F/R ratio. But as organic loading rate was increased from 8.54 to $12.04gTCOD_{Cr}/L$-day at the F/R ratio of 0.024, the removal efficiency of $SCOD_{Cr}$ decreased from 71% to 63%. The range of decreased removal efficiency of $SCOD_{Cr}$ at the F/R ratio of 0.024 was much more higher than at the F/R ratio of 0.303, 0.91. Thus, as organic loading rate was increased, ASBRs were operated with high F/R ratio to obtain high removal efficiency.