• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.5
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• pp.76-86
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• 2007

For the purpose of ground improvement by means of soil flushing systems. Incorporated technique with prefabricated vertical drains have been used for dewatering from fine-grained soils. The laboratory model tests were performed by using the flushing tracer solutions for silty soils and recorded the tracer concentration changes with the elapsed time and flow rates. A mathematical model for prediction of contaminant transport using the PVD technology has been developed. The clean-up times for the predictions on both soil condition indicate more of a sensitivity to the dispersivity parameter than to the extracted flow rate and vertical velocity parameters. Based on the results of the analyses, numerical analysis indicate that the most important factor to the in-situ soil remediation in prefabricated vertical drain system is the effective diameter of contaminated soil.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.8-14
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• 2004

To investigate the optimal operation factors in appling Soil Flushing Process, which use EDTA and boric acid composite as a flushing reagent, to the Cd(cadmium) and Cr(chromium) contaminated sites, Cd and Cr emediation rate was investigated at various experimental conditions; as EDTA concentration was increased from 0.001M to 0.1M, Cd remediation rate was increased from $73.2\%\;to\;98.5\%$; as boric acid concentration was increased from 0.001M to 0.1M, Cr remediation rate was increased from $59.2\%\;to\;99.0\%$. In the experiments using 0.005M of EDTA and 0.005M of boric acid composite as a flushing reagent at different pH regimes, Cd remediation rate was decreased from $92.4\%\;to;80.9\%$ as the pH was increased from 3 to 7. But Cr remediation rate was more effective ($70.4\%$) at pH 5 compared to the other pHs. Furthermore, at pH 5, Cd and Cr remediation rate was investigated at different molecular ratio of [EDTA]/[Boric aicd]; the optimized [EDTA]/[Boric acid] ratio was 0.01M/0.1M for Cd contaminated site and, as the concentration of boric acid was increased over 0.1M, Cr remediation rate was also increased. So the similar results were shown in the experiments using real contaminated soils which were sampled from a mining and a industrial area.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.4
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• pp.441-451
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• 2014

The flushing is important to maintain good water quality in water main. It is a technique of using water velocity to remove sediments in water distribution system. The variety of water quality problems can occur in a distribution system, so too can a variety of benefits be gained by system flushing. In order to effectively perform the flushing, the contaminants to be removed to set up and it can be solved, it is necessary to ensure the proper flow rate. In this study, the removal of contaminants present in the inner water pipe attached loose deposits such as fine particles of granular activated carbon, sand and iron corrosion product sought to derive flow rates. Thus, the constant observation of using pilot plant scale water distribution plant for the movement of floating characteristics of particles were assessed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.623-628
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• 2011

Micro EDM(Electric Discharge Machining) is one of the most powerful technologies which are capable of fabricating micro-structure without any problems from high cutting force. However, there is a significant defect in the part machining with deep holes or pockets, because debris which are generated by electric discharging may frequently cause a short circuit between an electrode and workpiece material. Vibration flushing can reduce the undesirable phenomena with dynamic flow of EDM fluid in a deep and choked area. In this study, Vibration flushing with solenoid is suggested and the results show that the method can generate a remarkable EDM efficiency with high amplitude at a low frequency in comparison with current vibration flushing methods with high frequency using piezo actuators.

• Membrane Journal
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• v.12 no.1
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• pp.8-20
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• 2002

In this study using $N_2$-back flushing, which wwas not the general back-flushing method of membranes, the discharged wastewater from a paper plant was filtrated by 4 kinds of tubular carbon ceramic ultrafiltration membranes. We could in vestigate effects of $N_2$-back flushing period, transmembrane pressure (TMP)and flow rate and find optimal operating conditions. The $N_2$-back flushing time (BT) was fixed at 40 sec, filtration times (FT) were changed in 4~32 min, TNP in $1.0~3.0kg_f/cm^2$ the flow celocities in 0.53~1.09cm/s. The optimal conditions were discussed in the viewpoints of dimensionless permeate flux ($J/J_0$), toal permeate volume ($V_T$) and resistance of membrane fouling ($R_f$). Optimal back-flushing period was BT/FT=0.167 (FT=8 min ), in which more $V_T$ was obtained than that in BT/FT=0.083 (FT=4 min) which was the most friquent back-flushing condition. Then rising TMP should increase the driving force, and more $V_T$ could be accumulated. And rising flow rate should decrease membrane fouling increase permeate flux, and more $V_T$could be produced. Average rejection rates of pollutants were higher than 95% for turbidity and 45~83% for $COD_{Cr}$, but rejection rates of total dissolved solid (TDS) were lower than 10%.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.541-548
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• 2017

A theoretical study on gas-liquid two-phase flow flushing systemnitrogen gas to the oil used for existing flushing equipment was conducted on the basis of ISO code so as to improve performance of existing high-temperature oil flushing equipment used in ocean plant facility drying field. For study, we analyzed process simulation results mixed fluid mixing ratio, temperature, Reynolds number and liquid hold up affectcleaning performance after designing oil-nitrogen gas mixture flushing system process. As a result, as the volume flow rate of mixed fluid increases with the tube diameter the volume fraction of the gas phase constant, the liquid fraction difference value at the inlet and outlet of horizontal hydraulic piping increases. It was found that the phase distribution between oil and nitrogen gas bubbles varies depending on the position the pipe lengthdirection. This change in phase distribution is expected to have a significant impact on the clean performance of an oil-nitrogen gas mixture flushing system.

• Journal of Soil and Groundwater Environment
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• v.21 no.5
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• pp.1-7
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• 2016

The removal of non-aqueous phase liquids (NAPLs) from groundwater using pure water, via pump and treat, is quite ineffective due to their low solubility and hydrophobicity. Therefore, the objectives of pilot tests were to select potentially suitable surfactants that solubilize tetrachloroethylene (PCE) and trichloroethylene (TCE) present as contaminants and to evaluate the optimal range of process parameters that can increase the removal efficiency in surfactant-enhanced soil flushing (SESF). Used experimental method for surfactant selection was batch experiments. The surfactant solution parameters for SESF pilot tests were surfactant solution concentration, surfactant solution pH, and the flow rate of surfactant solution in the SESF pilot system. Based on the batch experiments for surfactant selection, DOSL (an anionic surfactant) was selected as a suitable surfactant that solubilizes PCE and TCE present as contaminants. The highest recovery (95%) of the contaminants was obtained using a DOSL surfactant in the batch experiments. The pilot test results revealed that the optimum conditions were achieved with a surfactant solution concentration of 4% (v/v), a surfactant solution pH of 7.5, and a flow rate of 30 L/min of surfactant solution (Lee and Woo, 2015). The maximum removal of contaminants (89%) was obtained when optimum conditions were simultaneously met in pilot-scale SESF operations. These results confirm the viability of SESF for treating PCE and TCE-contaminated groundwater.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.473-477
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• 2000

The experimental study of die-sinking electrical discharge machining(EDM) was conducted for Cold Die Alloy Steel of SKD-11 with rotary electrode according to the peak current of 11A, 15A and 19A, and the duty factor of 0.24, 0.45. dielectric fluid flow through the electrode inside according to the change of electrode internal diameter during the EDM working. Material removal rate(MRR) was increased with flushing & rotation of electrode at the condition for the peak current of 15A, 19a but the MRR is decreased at the flushing only. The more surface roughness was obtained for the case of the flushing & rotation under the peak current of 19A.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.343-350
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• 2003

The range of applications of artificial neural networks(Am) in many branches of geotechnical engineering is growing rapidly. This study was undertaken to develop an analysis model representing ultrasonically enhanced soil flushing by the use of ANN. Input data for the model-development were obtained by laboratory study, and used for training and verification. Analyses involved various ranges of momentum, loaming rate, activation function, hidden layer, and nodes. Results of the analyses were used to obtain the optimum conditions for establishing and verifying the model. The coefficient of correlation between the measured and the predicted data using the developed model was relatively high. It shows potential application of ANN to ultrasonically enhanced soil flushing which is not easy to build up a mathematical model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.4
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• pp.295-302
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• 2002

PAHs (polycyclic aromatic hydrocarbons) deposited in soil are one of serious problems against sustainable land use. In this paper, chemical soil flushing in a packed sandy soil matrix using a natural surfactant, $\beta$-cyclodextrin (CD) was studied via a fluorescence spectroscopy and a dye labelling. The contaminants are lipophilic ring compounds- phenanthrene and naphthalene. Sand type and flushing intensity (rate and concentration) are chosen as important investigation variables. The removal efficiencies were proportional to flow rate, concentration, temperature of the flushing solution and voidity of the sand column. Initial sorption of the surfactant onto the soil matrix was found to be a key step while flow shear was more crucial in the latter steps. The residual portion of the surfactant, which was most likely to be due to the initial sorption, would not be so influential on this type of soil washing for long times. These results will be useful in future for pilot scale in situ washing and for establishing better soil washing strategy.