• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.1
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• pp.97-109
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• 2004

The disposal of stormwater is one of the major problems in urban water management. One method of reducing peak runoff rates and other detrimental impacts of stormwater is detention storage. Detention ponds as a water quality control alternatives have been investigated by a number of researchers. Recognizing multiple roles such as flood peak attenuation, pollution removal and aesthetic enhancement, the design and management of detentions ponds deserve more research. The purpose of this research is to establish design criteria wet detention ponds to improve water quality. Water quality in detention pond discharge might be improve with physical, chemical and biological alterations. Physical alteration was focused in this study. There are several methods for estimating the suspended solid control capability of wet detention ponds. Existing models of suspended solids removal are based on sedimentation and gravity settling theory. The pollutant trap efficiency of pond is a function of several interrelating factors. Detention time is the most important factor, because it determine gravity settling quantities of pollutants. Desirable modification of physical factors for improvement of water quality in wet detention ponds are volume ratio, area ratio, length to width ratio, depth, out let location, bottom soil type. In order to apply design procedure in actual site, Namak new town development area was selected.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.4
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• pp.350-352
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• 1988

This study was carried out to know the influence of turbidity of submerged water on photosynthetic rate of rice plant after water submerging treatment. Rice plants were transplanted in the pot at maximum tillering stage and they were sumberged for 3days at meiotic stage, 20days after transplanting, in the plastic container which had the clear and turbid water temperature adjusted around 24 to $25^{\circ}C$. Photosynthetic rate at 6 hours recovery after submergence was 41.5 to 54.2% compared to the control, but in the case of cultivar 'Nagdongbyeo', it was rapidly increased by 97.3 to 104.6% in the clear water and by 68.6 to 77.5% in the turbid water at 2 to 4 days recovery after submergence. Photosynthetic rates per plants at 6 hours to 4 days recovery after submergence were 128.3 to 245.5 $C_2$ mg.hr.$^{-1}$, in 'Samgamgbyeo' and 71.1 to 162.4 $CO_2$, mgㆍhr.$^{-1}$ in 'Nagdongbyeo' Photosynthetic rate to respiration ratio of rice plant recovery after submergence was lower compared to control plant and it was lower in 'Nagdongbyeo' than that in 'Samgangbyeo'.ngbyeo' than that in 'Samgangbyeo'.gangbyeo'.pos;.

• Nuclear Engineering and Technology
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• v.40 no.7
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• pp.561-570
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• 2008

When reactivity insertion such as refueling occurs in CANDU reactors, the power and the water levels are tilted in the upper outer zone of the LZCS (Liquid Zone Control System) and fluctuate unstably for a certain period of time (1-5 days). The instability described above is observed in most CANDU reactors in service around the world, but its root cause is unidentified and no solutions to this problem have been established. Therefore, this study attempted to prove experimentally and analytically that the root cause lies in the hold-up of light water on the top of the TSP (Tube Support Plate) due to the mismatch between net volumetric flow rate of light water and helium crossing the narrowed porous TSP installed within the LZCS compartment. Our method was to perform a hydrodynamic simulation of in/outflow of light water and helium. Two solutions for the aforementioned instability of LZCS are suggested. One is to regulate the compartment for both inflowing helium gas and outflowing light water; the other is to enlarge the flow paths of helium and light water within TSP. The former may be applicable to nuclear reactors in service and the latter to those planned for construction.

• Environmental Engineering Research
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• v.22 no.2
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• pp.210-215
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• 2017

Produced water is the largest wastestream of oil and gas exploration. It consists of various organic and inorganic compounds that hinder its beneficial use. This study compared the treatment of produced water in a batch suspended and biofilm activated sludge process. The biofilm carrier material was made from Gardenia Carinata shell. COD, $NH_4{^+}-N$ and $NO_3-N$ removal was monitored in both the suspended (control) and floating carrier bioreactors. The results show a rapid reduction of produced water constituents in the floating carrier bioreactor. COD, $NH_4{^+}-N$ and $NO_3-N$ removal was in the range of 99%, 98% and 97% for the floating carrier bioreactor whereas it was 88%, 84% and 83% for the control bioreactor. The rapid reduction of COD, $NH_4{^+}-N$ and $NO_3-N$ clearly indicate that the floating carrier materials served as an attached growth medium for microorganisms, improved the breakdown of produced water constituents and reduced inhibition of microbial metabolic activities.

• Journal of Korean Port Research
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• v.12 no.1
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• pp.95-104
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• 1998

Water pollution in a semi-enclosed sea area such as a bay due to stagnancy of water has been a serious water environmental problem. Recently, some kinds of new methods to activate the tidal exchange between an inner bay and an outer sea area by control of a tidal residual current have been proposed. However, these methods have several problems, that is, I). deterioration in a natural view due to building of huge structures, II). increase of risk of navigation in case of a submerged structure, III). limition of sea area where a tidal current can be controlled and IV). difficulty in removing those structures in case of occurrence of an unexpected impact on water environment. In this paper, a new method is proposed, which can solve all the above problems, to purify water quality in a semi-enclosed bay by creation and control of a pattern of a tidal residual current. The tidal residual current is controlled by unsymmetric structures, which change the properties of resistance according to the direction of flow, arranged on the sea bottom. In this study, several numerical and hydraulic experiments of tidal current and particle-tracking for various arrangements of bottom roughness in a semi-enclosed model bay were carried out. As a result of experiments, it becomes clear that it is possible to generate a new tidal residual current and to activate a tidal exchange by only operation of bottom roughness arrangement.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.6
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• pp.693-699
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• 2009

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.669-670
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.695-697
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.1128-1129
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.956-957
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• 2005