• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.1013-1023
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• 2003

This study was performed to improve water quality of stream by applying hydraulic structures (weir and river bed material) made of porous concrete. The physical and chemical characteristics of porous concrete were measured to estimate application possibility of it in hydraulic structures and it was considered as a proper material for the hydraulic structures. In the results of comparison for the component of matters attached on the hydraulic structures made of porous and ordinary concrete, DW (dry weight) amount attached on porous concrete was 1.6 times higher than that on ordinary concrete under the condition of the same flow rate but influence by flow rate (difference of 10 times) was not shown. Therefore, we could understand that the material of media was more important in DW amount than flow rate. The rate of AFDM (ash free dry mass) to DW also was more at porous concrete than at ordinary concrete. Especially, the high rates of nitrogen and phosphorous in matters attached on porous concrete verify that they were removed by assimilation, adsorption and metabolism of periphyton. The removal percentage of SS, BOD, COD, T-N and T-P by hydraulic structures applying porous concrete compared with ordinary concrete was increased by 34.6%, 36.9%, 33.9%, 18.3% and 21.6%, respectively. Therefore, applying porous concrete to hydraulic structure is expected to contribute to improvement of stream water quality.

• Korean Journal of Environmental Agriculture
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• v.18 no.1
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• pp.18-23
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• 1999

A numerical model of flow velocity in the standing water system is presented. This model(RMA-2), based on the 2-dimensional unsteady momentum and continuity equations, uses finite element techniques to simulate the distribution of velocity over a spatial location of lakes. The present model represents an improvement over existing numerical water quality models in that it can model the unsteady state and can, therefore, cope with time with a spatial location of standing waters such as lakes and large reservoirs. The model thus allows the engineer to do more accurate estimation of water flows and thus water qualities in standing waters where directions and velocities of the flow become more important for the simulation of the water quality than in running waters. Tests for the data collected in the lake "Paldang" indicates that the model works well under limited circumstances. However, to be more accurate estimation of velocity with the present model, accumulation of data for the measurement of velocities and renovation of geometrical conditions of the lake would be needed.

• Journal of Korea Water Resources Association
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• v.40 no.2 s.175
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• pp.183-190
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• 2007

Soil layer in vegetation filter strip is one of the very important factor for reduction of non-point pollutants by physical, chemical and biological reactions of it through infiltration process. This study was carried out to prepare more effective vegetation filter strip through modification of soil layer for river water quality improvement. Therefore, the main aims of this study are to compare and evaluate normal (straighten type) and modified (step type) vegetation filter strip, which make artificially change the soil layer to improve infiltration ability, through bench scale experiments. In the results of this study, vegetation filter strip of step type is much more highly reduction effectiveness of pollutants in surface flow compared with normal vegetation filter strip. In case of below effluent, however, it appeared that the vegetation filter strip modified soil layer showed lower reduction effectiveness of pollutants than the general vegetation filter strip. This result was judged because effluent through the vegetation filter strip of step type passed bigger size of aggregate or sand than the vegetation filter strip of straighten type. If we compare it as a definition of pollutant load to estimate total amount of reduced pollutants by vegetation filter strip, reduced pollutants load by step type showed higher than those by straighten type because below effluent amount relied on total effluent amount was higher at step type (4%) than at straighten type (2%). In conclusion, the vegetation filter strip of step type to improve infiltration effect is much more reduction effectiveness of pollutants than vegetation filter strip of straighten type.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.910-918
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• 2010

In recent years, riparian buffer system has been known as one of the effective best management practices. However, establishment of riparian buffer system in aspect of plant species and its position in the riparian buffer zone has not been investigated due to lack of efficient evaluation method for the analysis of water quality improvement with established riparian buffer system. To solve this problem, the SWAT-REMM prototype was developed by the researchers in Canada. But, SWAT-REMM model can not consider the $NO_3-N$ load into riparian buffer system through subsurface flow. Thus to solved this problem, Fortran code of SWAT-REMM model was modified. This modified SWAT-REMM system was applied to the Bonggok watershed. Three riparian buffer scenarios, 15 m, 10 m, 5 m width for tree and grass, were made to evaluate the effects of riparian buffer system on water quality improvement. Reduction efficiency of T-N by riparian buffer system of 15 m wide was the greatest (6 ~ 37%, depending on subwatershed characteristics) among 3 scenarios. It indicates that the reduction efficiency of T-N load has increasing-tendency, as buffer width increasing. The results obtained from the analysis showed that wide buffer zones are found to be more effective in reducing non-point pollutant than narrow buffer zones in the riparian buffer zone system. Hence, the SWAT-REMM model could be efficiently used for evaluation and design the most effective riparian buffer systems to reduce pollutant loads to the watershed although many limitations still exist in SWAT-REMM model.

• Korean Journal of Ecology and Environment
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• v.46 no.1
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• pp.116-127
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• 2013

At weekly intervals, we monitored continuous changes in water quality by constructed floating wetland equipped with the four different filter media (sponge, volcanic stone, activated carbon and magnesium hydroxide) in a eutrophic lake from March 2011 to May 2012. We also investigated phyto- and zooplankton communities both in the influent and the effluent water through the floating wetland. Over a 10-month time period, average turbidity (66%), suspended solids (79%) and chlorophyll-a (80%) concentrations were remarkably reduced in the effluent water compared to the influent (P<0.001). The average removal rates of $NO_2-N$ and $NH_3-N$ were 24% and 20%, respectively (P<0.05). The average removal rates of $NO_3-N$ and TN were less than 10% (P>0.05). On the other hand, the average removal rates of $PO_4-P$ and TP were more than 65% (P<0.01). Interestingly, the abundance of phytoplankton in the effluent was decreased about 2.6 times compared to that of the influent, whereas the abundance of zooplankton in the effluent was increased about 3.5 times compared to that of the influent. Overall, particulate matters (SS, Chl-a and TP) and dissolved nutrients ($NO_2-N$, $NH_3-N$ and $PO_4-P$) were particularly reduced at high rates. Therefore, application of our constructed floating wetland in a eutrophic lake improved the water quality and demonstrated a potential for algal bloom mitigation.

• Korean Journal of Ecology and Environment
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• v.39 no.4 s.118
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• pp.481-488
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• 2006

The field scale experiment was performed to examine the performance of the constructed wetland for nonpoint source (NPS) pollution loading reduction. Four sets (0.88 ha each) of wetland and pond system were used. After three growing seasons of the wetland construction, plant coverage increased to about 90% even without plantation from bare soil surfaces at the initial stage. During the start up period of constructed wetlands, lower water levels should be maintained to avoid flooding newly plants, if wetland plants are to start from germinating seeds. The average removal rate of $BOD_5$, TSS, T-N and T-P during the first two years was 5.6%, 46.6%, 45.7%, and 54.8%, respectively. The $BOD_5$ removal rate was low and it might be attributed to the low influent concentration. The early stage of wetland performance demonstrated the effectiveness of water quality improvement and was satisfactory for treating polluted stream waters. From the first-order analysis, T-P was virtually not temperature dependent, and $BOD_5$ and TSS were more temperature dependent than T-N. A pond-wetland system was more effective than a wetland-pond or a wetland alone system in water quality improvement, particularly to reduce T-P. Overall, the wetland system was found to be an adequate alternative for treating a polluted stream water with stable removal efficiency and recommended as a NPS control measures.

• Environmental and Resource Economics Review
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• v.23 no.4
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• pp.719-746
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• 2014

This study attempts to estimate the value of the water quality improvement by deriving the equilibrium price of the water pollutant emission permit for the imaginary water pollutant emission trading market. It is reasonable to say that there is already an implicit social agreement for the unit value of water pollutant, when the government set the Total Water Pollutant Loading System for the major river basin as a part of the Comprehensive Measures for Water Management, particularly for the Nakdong River Basin. Therefore, we can derive the unit value of water pollutant emission, which is already implied in the pollution allowance for each city or county by the Total Water Pollutant Loading System. Once estimated, it will be useful to the economic assessment of the water quality related projects. An imaginary water pollutant emission trading system for the Nakdong River Basin, where Total Water Pollutant Loading System is already effective, is constructed for the estimation of the equilibrium price of water pollutant permit. By estimating marginal abatement cost curve or each city or county, we can compute the equilibrium price of the permit and then it is regarded as the economic value of the water pollutant. The marginal net benefit function results from the relationship between the emission and the benefit, and then the equilibrium price of permit comes from constructing the excess demand function of the permit by using the total allowable permit of the local government entity. The equilibrium price of the permit would be estimated to be $1,409.3won/kg{\cdot}BOD$. This is within reasonable boundary compared for the permit price compared to foreign example. This permit price would be applied to calculate for the economic value of the water quality pollutants, and also be expected to use directly for the B/C analysis of the business involved with water quality change.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.40-48
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• 2010

Saemangeum reclaimed area is needed to construct much green zone to make high-quality multi-functional land such as tide embankment, lake dike, industrial complex, environmental spaces, etc. However, growth of plants is somewhat difficult because a salinity of Saemangeum soil is very high and a soil fertility, water content of soil are low. Therefore, it is essential to initial desalination of soil and continuous management for planting base. It is recommended that a group of grassland to raise the efficiency of covering should be made in the first stage and a forest by improvement of vegetation should be made in the mid and long term stage. It is recommended that the construction of vegetation base should be made with a regular thickness of soil of good quality in multi-functional area such as a shrub and wood. In case of construction of a windbreak forest, it is necessary to make a wood base of suitable depth using soil brought from another place or filling of soil. Also, it is necessary to keep a maintenance of woods in early stage. Saemangeum reclaimed land will be brand-named worldwide tourist attractions due to construction of much green zone having high quality multi-functional facilities.

• Food Science of Animal Resources
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• v.41 no.4
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• pp.636-649
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• 2021

The aim of this study was to evaluate the effect of three different strains of lactic acid bacteria (LAB) starter cultures: Pediococcus pentosaceus (KC-13100) (PP), Lactobacillus plantarum (KCTC-21004) (LP1), and L. plantarum (KCTC-13093) (LP2) on the physicochemical and microbiological characteristics, and sensory quality of dry fermented sausages after 21 days of drying and ripening period. Treatments added with PP and LP2 strains showed a significant higher (p<0.05) LAB and total plat counts, and water activity (a_w) of all three treatments was below 0.85 after the completion of the ripening process. A significant variation (p<0.05) in pH values of treatments was exhibited due to the difference in acidification capacity of the LAB strains: LP2PP>LP2. Substantial variations (p<0.05) in shear force values were detected amongst three batches (LP2>LP1>PP). In sensory attributes, PP treated samples had significantly higher (p<0.05) color and overall acceptability scores. The current findings proved how important the optimal assortment of starter culture. Inoculation with PP produced importantly beneficial effects on sensory quality improvement of dry fermented sausage.

• Korean journal of food and cookery science
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• v.31 no.6
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• pp.696-702
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• 2015

Rice dumpling shells were prepared with different levels of hydrocolloids, such as hydroxypropyl methyl cellulose (HPMC), and potato starch. After steaming, the physical, sensory, and cooking properties of the shells were measured. Increasing the amount of potato starch decreased the pasting temperature and increased the peak viscosity. With the addition of hydrocolloids, water absorption and cooking loss for the rice dumpling shells decreased significantly. For the textural properties, the rice dumpling shells with hydrocolloids showed lower hardness and higher springiness than the control, and especially, 10% potato starch and 3% HPMC addition (P10H3) improved the texture of the rice dumpling shells the most. The sensory results seemed to be affected more by the addition of potato starch than HPMC, and over 15% addition of potato starch significantly decreased the quality of the rice dumpling shells. By addition of adequate amount of hydrocolloids (3% HPMC and 10% potato starch), the sensory quality of rice dumpling shells can be effectively improved.