• The Journal of Engineering Geology
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• v.12 no.1
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• pp.75-88
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• 2002

When unsymmetrical surcharge is worked on polluted soft soils, large plastic shearing deformation such as settlements, lateral displacement, upheavals and shearing failure occured in the soils and they have often done considerable damages to the soils and structures. Accordingly, this study conducts laboratory pilots test to investigate the determination method of lateral flow pressure of polluted soft soils by comparing it to existing equations. The model test is performed that a model stock device is made and polluted soils are filled in a container which fires the soils. Then the displacement is observed as surcharge load is increased by regular intervals at untrained condition. The result shows that test the lateral flow pressure is adequately calculated by the equation (P=K$_{0}$YH) and the maximum value of lateral flow pressure Is found near 0.3H of layer thickness(H) and is higher to ground surface than synthesis pattern, Poulos distribution pattern and soft clay soils(CL, CH) which is not polluted.

• Asian Journal of Turfgrass Science
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• v.11 no.3
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• pp.193-203
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• 1997

This study was carried out to investigate the phytosociological method for analyzing vegetation composition, which would be one of the major keys of land use in Sinchun stream side-bed. The obtained results were as follows As the result of survey, following flora were observed. Most of plants composed of Graminea,Compositae, Leguminosae and Poligonaceae, 23, 17, 13 arid 9 species, respectively. In upper stream side-bed, E crus-galli var. caudata and Phragmites communis were well growed,which were effective for cleansing water. Otherwise both Polygonum species and Rumex were profused in Mid-stream side-bed and Down-stream side-bed, these plants were well growed in polluted stream. Key words: Phytosociological, Polluted stream, Sinchun stream side-bed, Taegu city.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.67-72
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• 2004

Many port states such as New Zealand, the USA, Australia and Canada have strict regulations to prevent ships which arrive in their port from discharging polluted ballast water which contain harmful aquatic organism and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason, they perceived that the ballast exchange in deep sea is the most effective method, together with submitting the ballast management plan which contains the effective exchange method, ballast system and safety consideration. In this study, we pursued both nautical engineering analysis and optimization of algorithm in order to generate the sequence of stability and rapidity. Heuristic Algorithm was chosen on the basis of optimality and applicability to a sequential exchange problem. We have built an optimized algorithm, for automatic exchange of ballast water, by redefining core elements of the $A^\ast$ algorithm, such as node, operator and evaluation function. Final version of the optimized algorithm has been applied to existing bulk carrier and the performance of the algorithm has been verified successfully.

• Journal of the Korean Chemical Society
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• v.57 no.2
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• pp.272-278
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• 2013

Extract of ginger has been evaluated as a green inhibitor for the corrosion of steel in sulfide polluted NaCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Potentiodynamic polarization measurements showed that this extract acts as a mixed type inhibitor but mainly inhibits the cathodic reaction. The inhibition efficiency was found to increase with inhibitor concentration reaching to approximately 83.9% using 250 ppm of ginger. Nyquist plots show a single capacitive loop in uninhibited and inhibited solutions. From EFM the causality factors are very close to theoretical values which indicate that the measured data are of good quality. The adsorption process of the studied extract on steel surface obeys Temkin adsorption isotherm. The results obtained from the different electrochemical techniques were in good agreement which prove the validity of these tools in measurement of corrosion rate. Ginger extract has no effect on Escherichia Coli and can be applied safely on waste water treatment plants.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.225-230
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• 2003

Many port states such as New Zealand, the USA, Australia and Canada have strict regulations to prevent ships which arrive in their port from discharging polluted ballast water which contain harmful aquatic organisms and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason, they perceived that the ballast exchange in deep sea is the most effective method, together with submitting the ballast management plan which contains the effective exchange method, ballast system and safety consideration. In this study, we make an effort to develop optimum ballast water exchange management and in result of that, it provide more convenient and stable process for preparing ballast water management plan.

• Journal of Ocean Engineering and Technology
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• v.18 no.4 s.59
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• pp.65-70
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• 2004

Many port states, such as New Zealand, U.S.A., Australia, and Canada, have strict regulations to prevent arriving ships from discharging polluted ballast water that contains harmful aquatic organisms and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason, ballast exchange in deep sea is perceived as the most effective method of emptying ballast water. The ballast management plan contains the effective exchange method, ballast system, and safety considerations. In this study, we pursued both nautical engineering analysis and optimization of the algorithm, in order to generate the sequence of stability and rapidity. A heuristic algorithm was chosen on the basis of optimality and applicability to a sequential exchange problem. We have built an optimized algorithm for the automatic exchange of ballast water, by redefining core elements of the A$\ast$ algorithm, such as node, operator, and evaluation function. The final version of the optimized algorithm has been applied to existing bulk carrier, and the performance of the algorithm has been successfully verified.

• Membrane and Water Treatment
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• v.10 no.4
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• pp.259-264
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• 2019

Cost effective clay adsorptive microfiltration membranes were synthesized to remove Cr (III) from high polluted water. Raw and calcined bentonite were mixed in order to decrease the shrinkage and also increase the porosity; then, 20 wt% of carbonate was added and the samples, named B (without carbonate) and B-Ca20 (with 20 wt% calcium carbonate) were uniaxially pressed and after sufficient drying, fired at $1100^{\circ}C$ for 3 hours. Then, physical and mechanical properties of the samples, their phase analyses and microstructure and also their ability for Cr(III) removal from high polluted water (including 1000 ppm Cr (III) ions) were studied. Results showed that the addition of calcium carbonate lead the porosity to increase to 33.5% while contrary to organic pore formers like starch, due to the formation of wollastonite, the mechanical strength not only didn't collapse but also improved to 36.77 MPa. Besides, sample B-Ca20, due to the presence of wollastonite and anorthite, could remove 99.97% of Cr (III) ions. Hence, a very economic and cost effective combination of membrane filtration and adsorption technology was achieved for water treatment which made microfiltration membranes act even better than nanofiltration ones without using any adsorptive nano particles.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.1
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• pp.44-55
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• 1998

Imgok creek is the most severly polluted one out of the streams which have been being polluted by acid drainages from the abandoned coal mines in the Gangdong-Myeon area, the central part of the so called Gangreung coal field. Imgok creek is being mainly polluted by the drainage from Youngdong coal mine, which supplies such pollutants as Mg, Fe, Al, Si, Ca, Mn, and SO$_4$as major dissolved components and Cr, Co, Ni, Cu, Zn, Rb, Sr, Cd, Pb, and U as minor dissolved components. After the influx, the pollutants migrate mainly as dissolved solid, rather than as suspended solids along Imgok creek. The suspended solids in Imgok creek are very rich in Fe and Al, indicating that they mainly consist of the precipitates of present and past from the polluted water. Most of the dissolved components in the stream waters of Imgok creek removed from the aqueous phase by precipitation and dilution before reaching the East Sea, so that water quality of the downstreams of Imgok creek is very similar to that of unpolluted tributaries. It suggests that Imgok creek itself is now being severly polluted by the acid drainages from the abandoned coal mines, but the East Sea is relatively safe from the same pollution. The estuary and sea waters around the Goonseon estuary, which accepts Imgok creek water, certainly show no significant difference in chemical compositions from the mean oceanic water. The bottom sediments at the sampling sites of the sea waters also show no significant trend of their component variation, especially the variations of Fe, SO$_4$ and Al concentrations. These facts again supper that the acid mine drainage is not considerablly polluting the East Sea. However, the tributaries supplying the fresh water to the Imgok creek will be certainly polluted by the acid mine drainage as time passes and pollutants will have more chance to migrate in significant amount to the downstream area, which all can be a real threats to the East Sea on the pollution possibility. Therefore, it is suggested that urgently required are not only water quality and environmental improvement of the severely polluted Imgok creek but also preparation of the measures on the possible future pollution of the East Sea by the acid drainage from the abandoned coal mines in the area, while the East Sea is still not much affected by the pollution of the same kind.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.4
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• pp.304-307
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• 1993

An experiment was conducted to evaluate the effects of silicate and potassium application on the yield of rice irrigated with polluted water and ground water. 1. The most important component affecting plant growth in polluted water was $NH_4-N$. 2. Rice grain yield was increased by silicate and potassium application, and yield increase of silicate and potassium was higher than that of single application of silicate and potassium. 3. The ratios of $SiO_2$/T-N and $K_2O$/T-N in shoot of rirc plant increased with silicate and potassium application, but the absorption of nitrogen by rice plant was decreased. 4. Lodging index was increased by the application of polluted water, and the application of silicate and potassium reduced the lodging.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.747-753
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• 2010

A series of experiments with a laboratory scale ultrasound treatment system for MTBE polluted groundwater was performed to increase the efficiency of MTBE degradation in groundwater. This study evaluated several factors to increase the efficiency of MTBE treatment for artificial and natural groundwater. The treated volume of groundwater, ultrasound frequency and power, and pollutant concentrations have been changed to evaluate its effects on the degradation efficiency of MTBE in batch and continuous flow reactor. For the specific experimental conditions on this paper, MTBE degradations are more efficient at 580 kHz than those at 1 MHz. The efficiency of MTBE degradation is proportional to the intensity of ultrasound power per unit volume of MTBE polluted groundwater. The concentration of ions in groundwater does not much affect the efficiency of MTBE degradation. The $1^{st}$ order degradation constant of MTBE for different power per unit volume at 580 kHz shows linear relationship at same concentration. The $1^{st}$ order degradation constant for 0.1 mM MTBE solution is higher than that for 1 mM MTBE solution. These experimental results could be helpful to seek optimal conditions for relatively large volume of polluted groundwater treatment.