• Journal of Wetlands Research
• /
• v.21 no.spc
• /
• pp.1-8
• /
• 2019

River works for water utilization have substantially altered the natural flow regime, and it has resulted in deformation of healthy river ecosystems. In Korea, river restoration projects have conducted actively since 1990's. Major purposes of the river restoration are the rehabilitation of modified river channel, improvement of water quality, and creation of aquatic habitats as well as recreational spaces using natural material for river work. However, there have been little interests about the restoration of flow regime which influences to most aspects of river ecosystems. The restoration of natural flow regime has received much attention in preservation of aquatic ecosystems. It should be needed to explore the relationship between flow regime and river ecosystems, and the restoring flow regime is essential. This paper introduce the concept of environmental flow through the interrelation between flow regime and river ecosystem. It provides rolls of flow regime and addresses the method of establishing target flow regime using the RVA(Range of Variability Approach) that suggested by Richter et al.(1997) through analysis of altered flow pattern case of Han river basin.

• Journal of Korean Society on Water Environment
• /
• v.29 no.1
• /
• pp.97-106
• /
• 2013

The temporal and spatial variations of water quality in a stratified reservoir are fully dependent on the characteristics of inflow loading from its watershed and the transport regimes of pollutants after entering the reservoir. Because of the meteorological and hydrological conditions in Korea, the pollutants loading to reservoirs are mostly occur during rainfall events. Therefore it is important to understand the characteristics of pollutants loading from upstream rivers and their spatial propagation through the stratified reservoir during the rainfall events. The objectives of this study were to characterize the water quality variations in upstream rivers of Imha Reservoir during a rainfall event, and the transport and spatial variations of pollutants in the reservoir through extensive field monitoring and laboratory analysis. The results showed that the event mean concentration (EMC) of SS, BOD, $COD_{Mn}$, T-N, T-P, $PO_4-P$ are 8.6 ~ 362.1, 2.5 ~ 5.1, 1.5 ~ 5.1, 1.1 ~ 1.9, 8.3 ~ 57.1, 5.6 ~ 25.7 times greater than the mean concentrations of these parameters during non-rainfall period. The turbidity and SS data showed good linear correlations, but the relationships between flow and SS showed large variations because of hysteresis effect during rising and falling periods of the flood. The ratio of POC to TOC were 12.6 ~ 14.7% during the non-rainfall periods, but increased up to 28.2 ~ 41.7% during the flood event. The turbid flood flow formed underflow and interflow after entering the reservoir, and delivered a great amount of non-point pollutants such as labile and refractory organic matters and nutrients to the metalimnion layer of reservoir, which is just above the thermocline. Spatially, the lateral variations of most water quality parameters were marginal but the vertical variations were significant.

• International Journal of Fluid Machinery and Systems
• /
• v.4 no.2
• /
• pp.255-261
• /
• 2011

Recently, as global-scale problems, such as global warming and energy depletion, have attracted attention, the importance of future environmental preservation has been emphasized worldwide, and various measures have been proposed and implemented. This study focuses on water hammer pumps that can effectively use the water hammer phenomenon and allow fluid transport without drive sources, such as electric motors. An understanding of operating conditions of water hammer pumps and an evaluation of their basic hydrodynamic characteristics are significant for determining whether they can be widely used as an energy-saving device in the future. However, conventional studies have not described the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps. As a first stage for the understanding of water hammer pump performance in comparison to the characteristics of typical turbo pumps, the previous study focused on understanding the basic hydrodynamic characteristics of water hammer pumps and experimentally examined how the hydrodynamic characteristics were affected by the inner diameters of the drive and lift pipes and the angle of the drive pipe. This paper suggests the effect of the air volume in the air chamber that affects the hydrodynamic characteristics and operating conditions of the water hammer pump.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2002.05a
• /
• pp.101-106
• /
• 2002

In the Refrigeration and air conditioning industrial circles, refrigerator is demands a high degree of efficiency due to the Environmental Preservation Law. Many researchers are working on factors to improve the efficiency of the refrigerator In this paper, a study of the factors on the decrease of electric power consumption, several experiments are performed to improve the fluid flow in the refrigerator machine room. As a results, average temperatures of compressor and condenser are reduced 3.1$^{\circ}C$, 2.$0^{\circ}C$. The consuming electric power rate is reduced 0.7kWh/month.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.13 no.6
• /
• pp.133-144
• /
• 2010

The objective of this planning proposal is to rehabilitate the urban stream which has been ecologically disturbed in the urban process. The experimental stream, Su-am stream located in Anyang City is typical urban stream in adjacent land use and the spatial condition. The stream in the watershed context, is the second tributary of Han River, in the Anyangcheon watershed. The Characteristics of the stream reach were analyzed by the river corridor survey. In the conceptual phase, Rehabilitation Programs were established based on the hydrological, ecological and spatial characteristics of the stream. Spatial zoning concept according to the characteristics of the stream and adjacent land use, was suggested 4 types of zoning; ecological preservation zone, natural landscape zone, neighborhood water-friendly zone and CBD water-friendly zone. Implementation Practices can be summarized as follow: For The longitudinal river continuum, some In-stream practices were suggested and implemented; such as channel alignment, step & pool, pool & riffle and low-flow channel bank. For latitudinal continuum and intimate spatial relationship between Sam-duk Park & Su-am stream, gentle sloped bank was planned and implemented. After stream improvement & ecological Implementation, follow-up monitoring and adaptive management programs will be a meaningful process for ecological rehabilitation.

• Journal of Environmental Science International
• /
• v.10 no.1
• /
• pp.65-71
• /
• 2001

HRP(high rate pond) which had kept the manufactured clay of 3cm-thickness as benthic clay in reactor and the 6 flat-blade turbine as impeller for agitation was named HRASP(high rate algae stabilization pond). And the experiment for treatment of artificial synthesis wastewater containing COD :300mg/$\ell$, NH$_3$-N : 300mg/$\ell$, T-P : 9mg/$\ell$ as nutrients was been performed successfully. This reactor was been operated under conditions : 24hrs.-irradiation and water temperature, $25^{\circ}C$ and pH 7 and agitation velocity, 15, 30, 45rpm and the effect of agitation velocity on algal bioaccumulation of nutrients was been studied with view point of fluid dynamics. The next followings could be obtained as results. 1. The agitation with a turbine impeller blade in HRASP makes clay particle indicate superior suspension effect by means of forming of excellent curl/shear flow in reactor. 2. The excessive suspension of clay particle which is created at 45rpm as rotation velocity of impeller blade of turbine disturbs the light penetration and algal photosynthesis reaction. 3. Efficiencies for removal of nutrients come out as COD : 93.9%~94.3%, ($NH_3-N + NO_3-N$) : 81.9%~99.0%, T-P : 46.8%~53.6%. 4. Kuo values of $K_1$for algal growth come out seperately as 15rpm : $1.876{\times}10^{-2}, 30rpm : 4.618{\times}10^{-3}$. 5. Kuo values of $K_2$for removal of N, P come out seperately as 15rpm : $8.403{\times}10^{-1}$ and $1.397{\times}10^{-1}$, 30rpm : $4.823{\times}10^{-1} and 2.052{\times}10^{-1}$. 6. It can be guessed easily that the excessive agitation can inhibit the algal and bacterial symbiotic reaction if it is considered that micro organism\` sense to preservation of life is relied on natural function of metabolism. Therefore the studies for this matter should be followed continuously.

• Journal of Korean Society on Water Environment
• /
• v.36 no.2
• /
• pp.125-136
• /
• 2020

In this study, we identified the major pollution-zones of the mainstream and its tributaries of Gongneung stream and investigated their pollution sources based on water quality, flowrate and pollution-load data of the stream having the characteristics of the urban-rural complex to examine the effect of the tributaries on the water quality changes in the mainstream. The water quality and flowrate data were collected for 10 months (2018 ~ 2019) at 3 points of mainstream and ten tributaries. Water quality index (WQI), load duration curve (LDC), discharge load density (DLD)and delivery ratios for each tributary were obtained so as to investigate the pollution characteristics and some of the information visualized on GIS. The main pollution-zone in the Gongneung stream was in the middle and lower streams, and the tributaries that may affect the pollution of the area were JS, JY, SL and SM. JS and SL had low WQI levels (34.7/37.5) and DLD (kg/d/㎢) of BOD and T-P were relatively high in JY (99.2/6.00) and SL (60.0/2.07). BOD and T-P delivery ratios in JS were high (0.94/0.83), suggesting that JS had significant influence on the water quality of the main pollution-zone in the Gongneung stream. Meanwhile, SM having a high T-P delivery ratio (0.97) was found to be more affected by the non-point source due to the higher LDC excess rate (%) in the low flow compared to high flow. This study provides basic data on the water quality and pollution characteristics of the Gongneung stream, and the analysis results are expected to be used as examples for identifying the main pollution-zone and tributaries of stream and their pollution sources.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.13 no.3
• /
• pp.198-205
• /
• 2010

The purpose of this study is to investigate the characteristics of the grain size distribution and organic matters to understand the current status of the tidal flat sediment for efficient management of Suncheon Bay. We investigated the characteristics of the surface sediments in the mouth area of the Suncheon Bay at fifteen stations in April and July, 2009. Specific conclusions were as follows. The sediments in the most part of tidal flat was shown as muddy facies(clay and silt contents was more than 90%), whereas in the tidal river affected by water flow from the Dongstream was shown as sandy facies. The analyzed values of the tidal flat sediment were in the range of $1.9{\sim}3.8{\phi}$(mean $2.5{\phi}$) for sorting, and -1.5~3.2(mean -0.3) for skewness, and 1.5~14.1(mean 3.9) for kurtosis. So we knew that the tidal flat sediments in the Suncheon Bay was mainly composed by fine-grained sediment. Erosion was happened in the tidal river, whereas sedimentation was occurred in the tidal flat. The most of organic matters was derived from the Dongstream. Total organic matters shown as ignition loss was 5.75%, COD and $H_2S$ values were lower than the eutrophication level(COD; 20.0 mg/g dry, $H_2S$; 0.2 mg S/g dry). From our research the tidal flat of the Suncheon Bay is relatively fine, but a part of the flat was exceed the environmental standard. So we have to establish effective countermeasures to reduce the organic matters and nutrients derived from stream for environmental preservation of the Suncheon bay and conduct scientifically sustainable monitering for streams flowing into Suncheon Bay and tidal flat.

• Ecology and Resilient Infrastructure
• /
• v.10 no.4
• /
• pp.250-257
• /
• 2023

Tree in river have environmental functions such as ecosystem preservation and flood control functions that protect the riverbank. On the other hand, excessive tree development can have the negative effect of fixing the sand bar and reducing the cross-sectional area. Nays2D simulation results performing two flow conditions (average dam operation discharge and two-year frequency discharge) and four tree density conditions (current, zero, low, high tree density) used as input data for PHABSIM to calculate WUA (Weighted Usable Area). The results show that riverbed changes occur more significantly in the zero tree density than presence of trees, which could have a positive impact on the biological habitat environment of Zacco platypus.

• Journal of Wetlands Research
• /
• v.22 no.4
• /
• pp.225-238
• /
• 2020

The agricultural landscape is considered an important space to provide service functions, but the reality is that environmental and ecological problems are being reported in the creation of a facility horticulture complex. Therefore, this study was conducted to contribute to sustainable agriculture by creating a more eco-friendly facility horticultural complex. The elements of planning for eco-friendly development of the facility horticultural complex were derived from literature and expert surveys. The master plan and the bird's-eye view were then applied to the Saemangeum area by applying the planning elements. After analyzing the method of selecting and deploying input elements for improving functions, it was suggested that low-flow areas, wetlands, artificial storage facilities, green spaces, and waterways should be placed in harmony with the landscape and that the building-to-land ratio should be applied at 55%. The final design was prepared by applying the ecological service function improvement plan proposed by experts. The final bird's-eye view also reflected water purification facilities, connection of wetlands to waterways, packing of pitchers, and connection of green areas. The results of the research are expected to be used as basic data for policy and budget allocation for the eco-friendly creation of horticulture facilities and contribute to sustainable agriculture by contributing to national biodiversity and environmental preservation.