• Water for future
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• v.35 no.5
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• pp.43-50
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• 2002

The Yellow River Basin located in the Northern part of China is well-known not only as the seriously limited water sources but the greatest sediment-carrying stream in the world. The observed annual average sediment concentration in this area is $37.6kg/\textrm{mm}^3$, and 3.1% of the water volume is occupied by sediments. Due to the reason, water development has been extremely limited and it has been appeared as one of the most difficult problems in reservoir development and management. The major obstacle to surface water uses is reservoir sedimentation so that it has been strongly requested to seek the method managing sediment by optimal fashion. To solve this problem, KOWACO (Korea Water Resources Corporation) has developed various methods on the optimal reservoir management schemes including sediment management for the Upper Fenhe Basin Reservoir System at the cooperation project with Chinese. Information Variable Dynamic Programming. which is one of them, was developed for the reservoir sediment management and a set of non-dominated solutions are generated to choose the best alternative in water supply and reservoir sediment objective problem.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1061-1064
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• 2008

A completion of settling process takes a lot of time for dredged materials of high moisture content, such as contaminated sludge, in landfill site. In general, additives (e.g. flocculants) are used for reducing settling time of such colloidal material, which results in the increase of sludge volume, and hence much space is required in landfill site. This study is to suggest alternative method in order to enhance the settling process of cohesive clayey soils. A number of gravitational sedimentation tests as well as electrokinetic experiments were conducted to investigate the variation of initial moisture content on the settling behaviour of clay slurry. Surface settlement, electric current and local voltage gradient were monitored during the experiment, and moisture content and soil pH were measured after the experiment. From the results, the application of electrokinetics was found to be effective in volume reduction (i.e. increase of settling velocity and decrease of final moisture content) by comparison with gravitational settling process.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.301-310
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• 2006

A series of laboratory tests was carried out for analyzing compaction characteristics of hydraulic fill soils(or hydraulically filled soils). Hydraulic fill soils were settled down by the weight of soil particle itself in water and consolidated by the extraction of water from the soil structures. Water content and dry unit weight were observed as the depth of sedimentation and consolidation soil. It was found from the result that the optimum water content $(W_{cpt})$ of the maximum unit weight$(\gamma_{dmax})$ is higher than that of laboratory compaction test(KS F 2312 A method). It was due to difference in compaction energy and compaction effect between two methods. And the maximum dry unit of hydraulic fill soil is smaller than that of laboratory compaction test. Especially in terms of compaction effect, the maximum relative compaction degrees$(R_{cmax})$ of Seamangum dredged sand, river sand and mixed sand, half and half of dredged and river sands, were 85%, 91% and 86%, respectively. It means that the compaction effect can be $85\sim91%$ of the maximum unit weight in laboratory compaction test.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.373-378
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• 2008

The pH & alkalinity adjustment method by lime and carbon dioxide($CO_2$) for corrosion control in water distribution system was investigated to determine the optimum operational condition in lime adding process in water treatment plant(WTP). The mixing time at dissolution tank and sedimentation time at saturator for maintaining optimal turbidity condition of lime supernatant were 60~75 minutes and 75~95 minutes, respectively. There was no difference according to $CO_2$ adding methods such as $CO_2$ saturated water or $CO_2$ gas. But, $CO_2$ saturated water could be convenience at WTP in terms of pH control and quantitative dosing. To minimize generation of calcium carbonate products, the short time interval between adding of lime and $CO_2$ is most important. The lime should be added below 32 mg/l for preventing pH rising and generation of calcium carbonate products at the heating condition.

• Journal of Environmental Science International
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• v.12 no.3
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• pp.281-286
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• 2003

This study was conducted to evaluate the feasibility of ammonia removal by zeolite adsorption in drinking water treatment. In generally, drinking water treatment process is conducted coagulation/flocculation, sedimentation, sand filtration and disinfection. We tested feasibility with two method, one is powdered zeolite dosing to coagulation tank and the other is to substitute granular zeolite for sand of sand filter. In powdered zeolite test, raw water is used tap water with putting of 2 mg/l of NH$_4$$\^$+/-N. Filtration of granular zeolite was conducted with 80 cm of effective column high and 120 m/d of flow rate. At above 100 mg/1 of zeolite dosage, ammonia concentration was decreased below 0.5 mg/l of NH$_4$$\^$+/-N in powdered zeolite test. But, turbidity was increased to 30 NTU by powdered zeolite dosage. That turbidity was scarcely decreased in generally coagulant using condition in drinking water treatment. In granular zeolite test, ammonia was not detected in treated water until 8 days. This result suggest that using of granular zeolite in sand filter could be removal ammonia in winter. But we need regeneration at zeolite filtration for ammonia removal. So, it is to make clear that zeolite regeneration ability was compared KCl with NaCl. The result reveal that KCl was more excellent than NaCl. Optimum regeneration concentration of KCl was revealed 100 mM. Regeneration efficient was not increased at pH range 10∼12.5.

• Korean Journal of Animal Reproduction
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• v.3 no.1
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• pp.36-40
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• 1979

This experiment was conducted to separate X-and Y-bearing spermatozoa of boar semen. The ratio of X-and Y-bearing spermatozoa to total spermatozoa included in ejaculated semen obtained from 4 boars raising at the College of Agriculture, Seoul National University and treated by the sedimentory or electrophoretic technique was estimated. For the electrophoresis, the semen specimen was placed into the co, pp.r loop electrodes in 30cc of glass tube at room temperature for 30 minutes and in order to sedimentary separation, the semen was sedimented in 5$^{\circ}C$ water for 50 minutes. The sperm fluorescent stainning technique was performed by the method of Bhattacharya etal (1976). The results obtained were as follows; 1. Average rate of B-body bearing spermatozoa in normal boar semen was 45.15${\pm}$4.20%, and no significant difference was observed between 1st (44.88${\pm}$6.41%) and 2nd (42.75${\pm}$4.17%) fraction of fractionally collected semen. 2. Spermatozoa were separated into several different fractions by sedimentation. B-body a, pp.arances from the top and bottom fraction were 53.70% and 33.43%, respectively. There were highly significant difference between the top and bottom fractions. 3. The swine spermatozoa were separated into X-and Y-bearing spermatozos by electrophoresis without interferring the sperm motility. The rates of B-body bearing spermatozoa attracted on the anode and cathode were 60.4% and 21.8%, respectively. Highly significant difference betwee two fractions was also observed.

• 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 Veterinary Service
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• v.21 no.4
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• pp.391-400
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• 1998

In order to survey the prevalence of intestinal parasites in dogs, 304 fecal samples were taken from dogs in Taejon city, The prevalence and identification of intestinal parasites were determined by the fecal examinations using sheather's floating technique and sedimentation methods and then Cryptosporidium oocysts were identified by kinyoun's modified acid fast stainning method. The results were obtained as follows ; 1. Parasite eggs and oocysts were detected in 105 samples (34.5%) from 304 cases of dog feces. 2. The 11 kinds of eggs and oocysts were isolated from the feces of dog. Those were Ancylostoma caninum (12.1%, 37 dogs), Trichuris vulpis (11.5%, 35 dogs), Toxocara canis (10.2%, 31 dogs), Isospora sp (7.2%, 22 dogs), Cryptosporidium sp (3.6%, 11 dogs), Toxascaris leonine (1.9%, 6 dogs), Strongyloides sp (1.9%, 6 dogs), Taenia sp (0.6%, 2 dogs), Diphylidium caninum (0.3%, 1 dog), Spirometra sp (0.3%, 1 dog) and Clonorchis sinensis (0.3%, 1 dog). 3. It was mixed infection such as single, double, triple and quadruple, 64.8%, 25.7%, 8.6% and 0.9%, respectively. 4. In indiviually-raised 4095, the infectious late of T canis (11.4%), A Caninum(13.2%), Cryptosporidium sp (6.1%), T leontna (2.6%) were higher than those of group raised dogs. But the infectious rate of T vulpis (12.1%) in group raised dogs was higher than that of individually-raised dogs. 5. Adults of Demodex and Sarcoptes which have been found in this survey are excluded in this report.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.175.1-175.1
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• 2011

A rotating activated bacillus contactor (RABC) process with a series of aerobic reactors was tested in pilot scale to treat digested liquid from an anaerobic digester treating swine wastewater and sewage sludge. The influent (digested liquid) for the RABC process showed C/N ratios less than 2 as a typical feature of effluent from anaerobic digesters. The pilot process, which consists of three 3 RABC reactors, four aerobic tanks and a sedimentation tank, was operated for 210 days with a hydraulic retention time of 20 days without pH and temperature control. Since the Bacillus-enriched aerobic reactors shows high efficiencies of nitrogen removal at low DO levels less than 1.0 mg/L, they were operated at reduced aeration intensities. With relatively low concentrations of organics in comparison with nitrogen concentrations, the RABC process tested in this study showed stable and high nitrogen and organics removal efficiencies over 80%. The nitrogen removal process tested in this study was proven to be an effective and operation-cost saving (lower aeration) method to remove nitrogen without adding external carbon sources to meet the optimum C/N ratio.

• Journal of Korea Water Resources Association
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• v.34 no.3
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• pp.199-207
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• 2001

Due to the nationwide development, sediment yield has to be estimated to design the sedimentation basin which is used to minimize the effects of construction or disturbing the natural soil condition. But there is no proved equation for the estimation of sediment yield in Korea. Therefore, applicability and the limitation of RUSLE (revised universal sediment loss equation) sediment yield equation is examined for the construction sites, where the rainfall and sediment data are available. General mistakes in estimation of the RUSLE parameters are also discussed. It is found that RUSLE could be applied in Korea as long as the sediment delivery ratio was considered. Appropriate estimation method of sediment delivery ratio are also proposed.