• Journal of Korean Society on Water Environment
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• v.29 no.5
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• pp.656-665
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• 2013

This research was conducted to investigate pollutant load unit factor from aquacultural farms. Pollutant load unit factors were investigated on the 13 kinds of fish type, i.e., Trout, Leather Carp, Eel, Carp, Cartfish, Freshwater Eel, Crucian Carp, Colored Carp, Sturgeon, Marsh Snail, Sweetfish, Pond Snail, Eriocheir Sinensis. Water qualities in aquacultural farms were investigated wide range of values by fish type and pollutant items. High BOD and COD values were observed at the Leather Carp (Ponded water system), Cartfish (Ponded water system) and Freshwater Eel (Recirculating System). TOC and DOC values were relatively high at the Freshwater Eel (Recirculating System) and Eriocheir Sinensis (Extensive). Eel (Ponded water system) and Freshwater Eel (Recirculating System) produced high concentrated nutrient pollutants, i.e., T-N, T-P. Pollutant load unit factors are dependent on fish type, aquacultural type, water quality items, etc. If some fishes have similar basic unit values, those could be applied for TMDLs as a group of fish having same pollutant load unit. The water quality concentrations of post treatment facilities' (mainly reservoir tank) effluent were higher than those of fish raising bath because of extracting pollutant from sediment in the reservoir tank. Therefore, it needs to the management and regulations about post treatment facilities.

• Geophysics and Geophysical Exploration
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• v.18 no.3
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• pp.143-153
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• 2015

Polymer flooding for enhancing hydrocarbon production injects into a reservoir polymer solution that is viscous. It is very important to monitor the behavior pattern of the polymer solution in order to evaluate the effectiveness of polymer flooding. To monitor the distribution of polymer solution and thus fluid substitution within the reservoir, we first construct seismic and resistivity rock physics models (RPMs), which are functions of reservoir parameters such as rocks and type of fluid, fluid saturation. For the seismic and resistivity RPMs, responses of seismic and electromagnetic (EM) tomography are numerically simulated as polymer injection, using two dimensional (2D) staggered-grid finite difference elastic modeling and 2.5D finite element EM modeling algorithms, respectively. In constructing RPM for EM tomography, three different reservoir rocks are considered: clean-sand, dispersed shale-sand, and sand-shale lamination rocks. The polymer solution is assumed to have 2 wt% of polymer as normally generated, while water is freshwater or saltwater. Further, neutron logging is also considered to check its sensitivity to polymer flooding. The techniques discussed in the paper are important in monitoring not only hydrocarbon but also geothermal reservoirs.

• Korean Journal of Ecology and Environment
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• v.46 no.3
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• pp.343-359
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• 2013

In order to understand shoreline environment characteristics of Korean reservoirs, the interrelationships between environmental factors of geomorphology, hydrology, water quality and shoreline soil were analyzed, and the reservoir types were classified according to their environmental characteristics in the 35 reservoirs selected by considering the purpose of dam operations and annual water-level fluctuations. Geomorphological and hydrological characteristics of reservoirs were correlated with the altitude and the size scale of reservoirs. The annual range of water level fluctuation showed a wide variation from 1 m to 27 m in the various reservoirs in Korea. The levels of eutrophication of most reservoirs were mesotrophic or eutrophic. From the result of the soil texture analysis, sand contents were high in reservoir shorelines. Range, frequency and duration of water-level fluctuation were distinctive from the primary function of reservoirs. Flood control reservoirs had a wide range with low frequency and waterpower generation reservoirs had a narrow range with high frequency in the water-level fluctuation. According to the result of CART (classification and regression tree) analysis, the water quality of reservoirs was classified by water depth, range of water-level fluctuation and altitude. The result of PCA (principal component analysis) showed that the type of reservoirs was classified by reservoir size, water-level fluctuation, water quality, soil texture and soil organic matter. In conclusion, reservoir size, the water-level fluctuation, water quality and soil characteristics might be major factors in the environment of reservoir shorelines in Korea.

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.57-65
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• 2014

Spatial and temporal distributions of zooplankton were measured in an oligotrophic pumped storage-type hydroelectric reservoir which was composed of two reservoirs exchanging water daily, with water going up at night and going down during the day. Repetitive diel disturbance of the water column can be a unique feature of this reservoir system. Chl-${\alpha}$ concentration was highest in the early winter season. Phytoplankton density was lower in summer monsoon due to high flushing rate on rainy days. The zooplankton density was higher in the smaller upper reservoir possibly due to lower fish density in the upper reservoir. In the seasonal variation a time gap was observed between the phytoplankton bloom and the zooplankton bloom (particularly a rotifer, Keratella cochlearis). It is likely to that Keratella production is partially supported by heterotrophic food sources than phytoplankton. The dominance of a mixotrophic dinoflagellate (Peridinium bipes f. ocultatum) might have complicated the trophic relationship between phytoplankton and zooplankton. Our results provide some ecological information of zooplankton community in a highly disturbed alpine reservoir ecosystem relying on mostly allochthonous organic matter.

• Journal of Power System Engineering
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• v.4 no.3
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• pp.55-61
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• 2000

In this study, a new design of an one-body type of an unbalanced-fixed- displacement type vane pump combined with an induction type electric motor was suggested. By the application of the new design scheme, it was possible to reduce the number of parts of the pump system and to cut down the volume of power package than that of already-used products. The case in this study enabled efficient heat transfer and electricity insulation of hydraulic fluid. Thus oil moves through the inside of the package for cooling and returns to the reservoir. Because of this design, it was difficult to measure the shaft-input torque. Therefore the package overall efficiency in the paper was evaluated with a ratio of hydraulic power and electric power.

• Journal of Technologic Dentistry
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• v.23 no.2
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• pp.151-160
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• 2002

The purpose of this study was to evaluate the influence of sprue joint form on castability in dental prosthetics. The researcher carried out experimental study according to the type was divided by sprue joint form. Therefore type A was made thicken than sprue diameter of type B and type C was made it conversely. The results were as follows: 1. In the order of castability, type C(87.8%) was first and then type A(87.0%) and type B(79.2%) was last. However there was no significant difference statistically. 2. If reservior was located at the correct position and in sufficient size, internal shrinkage porosity in the casting bodies were not generated in the type of all. 3. At the reservoir, internal shrinkage porosity was generated first in type A, followed by type Band type C in the order named. Although it gives no impact on casting body, porosity seems to appear the least when it's produced in the form of type C.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.8
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• pp.146-154
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• 1997

Solenoid-folw control type ABS is used with a 'dump and reapply' pressure control arrangement instead of using 2/2 (normal open/close) solenoid valves in convensional systems(sol. -sol. control type), a flow control valve is used which replaces the (no) inlet valve. The flow control valve controls fluid flow providing a nearly constant reapply rate( .theta. ) after the dump plase of ABS operation. In this study, to investigate a characteristics of brake pressure by PWM control, test rig was consisted of ABS hydraulic modulator, digital controller, pneumatic power supply and brake master cylinder. For comparison with experi- mental results, system modelling and computer simulation were performed. As a result, experiment results showed fairly agreement with the simulation. Also, it is shown that the pressure gradient (tan .theta. ) is affected by pressure, frequency, duty ratio and expressed with an exponential funtion.

• Korean Journal of Environmental Agriculture
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• v.28 no.2
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• pp.125-130
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• 2009

The aim of this study was to investigate whether differences in the distribution of soil invertebrates among different vegetation types (forest, reservoir, and crop land types) in rural area. A total of 18 orders and 137 species were collected by pitfall traps. Species numbers were the lowest (33 species) at the Chamaecyparis obtusa plantation (St. 6). On the forest sites, the individual number of Hymenoptera was the most abundant, and Acari and Coleoptera was the relatively more abundant than the other sites. On the reservoir sites (Salix chaenomeloides community), the individual number of Collembola was the most abundant, and Diptera was the relatively more abundant than the other sites. On the crop land sites, the individual numbers of Collembola, Hymenoptera, and Araneae were the relatively more abundant than the other orders. The density of Araneae was higher in the reservoir and crop land sites than in the forest sites. From a point of view of biodiversity, although the diversity index(H') was the highest in the mixed broad-leaved forest type (St. 2) with Quercus serrata and Q. acutissima, and the lowest in the upland levee of crop land(St. 11), there was no significant difference among the habitat or vegetation types. According to the community analysis, the soil invertebrates could be divided into 4 groups, the mixed broad-leaved forest type (A group), the plantation or pure forest type (B group), the reservoir type (C group), and the crop land type (D group).

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.5 s.112
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• pp.69-82
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• 2005

These studies were carried out (1) to investigate the growth characteristics of Sedum album L. in the field, (2) to propose a suitable shallow peen roof system for this plant, and (3) to evaluate plant growth in the proposed system over the long term. The growth characteristics, such as morphological properties, growth habit, shade tolerance, and flowering, were surveyed. In experimental shallow green-roof systems, the effects of drainage type, substrate type, and soil depth on plant growth were investigated. Then drought tolerance was investigated. After planting Sedum album L. in the proposed system survival rate, cover, and resistance to insects, heal and cold were evaluated for about 2 years. The results of these studies are summarized below. 1. In the field, the aboveground part of Sedum album L. did not die back during the winter. Plant height was 4$\sim$7 cm. Roots were distributed to a depth of 5$\sim$7 cm. Sedum album L. is a compact ground-cover plant that spreads vigorously. Shading condition of less than $30\%$ of full sunlight didn't cause any trouble, but shading conditions above $87\%$ made the shape of the shoots and leaves abnormal. The plant bloomed from June to August and had a rather large compound umbel of white, star-shaped flowers. 2. Two systems, a drainage-blend-10 cm soil depth and a reservoir$\cdot$drainage-blend-15 cm soil depth, performed best in terms of cover, fresh weight, and dry weight. The first has an advantage for green roofs because it is lighter than the latter. 3. In drainage-blend-10 m soil depth and modified reservoir · drainage-blend-10 cm soil depth system no plants died for about 4 months after stopping the irrigation. The visual quality of the latter system was above 5 for 4 months and that of the former was under 5 after 2 months. In the field, however, the drought tolerance of Sedum album L. grown in the former would be enough to withstand the dry season. Considering the urban ecosystem and the importance of healthy growth the modified reservoir $\cdot$ drainage-blend-10 cm soil depth system was finally recommended. This system was composed of a 4 cm thick drainage layer and drain outlets placed at a height of 2.5 cm. 4. In the proposed system, the survival rate was $100\%$, and there was no injury induced by insects and heat. The leaf density decreased a little in winter. Cover increased throughout the year. Sedum album L. was planted with a cover of 72$cm^{2}$ on 3 April 2003; on 16 June 2003 and 15 June 2004, cover was $132.66\pm$5.87 $cm^{2}$(1.8 times) and $886.98\pm$63.51 $cm^{2}$(12.3 times), respectively.

• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.213-226
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• 2004

The present study was conducted to analyze the pattern of eutrophication of Korean reservoir with Chl. a concentration and morpho-physical parameters, and to valuate water quality characteristics of the classified types. The collected data from 486 reservoirs were classified as four types, with the Chl- a concentration (25 ${\mu}g\;L^{-1}$) and the ratio of water storage/surface area (mean depth, 7.5 m). According to OECD criteria and trophic state index based on Chl-a concentration, 34.3 and 72.8% of selected reservoirs appeared to be eutrophic, respectively. Characteristics of TYPE ll reservoirs generally showed high Chl-a concentration, relatively old age, small DA/LA ratio, short Hydraulic retention time, large paddy field and field to watershed ratio, and high pollutant loading compared to other types of reservoirs. The difference of TP concentration was greater than that of TN concentration in reservoir water among classified four types. Based on TN/TP ratio (by weight), phosphorus was limiting nutrient in all types and more closely related with Chl- a concentration than nitrogen. Significant decrease of Chl- a concentration with increase of TN/TP ratio observed only in reservoirs with Chl-a concentration > 25${\mu}g\;L^{-1}$. Although drainage area is believed to be a factor that is related to the generation load of pollutants in the watershed, it did not show any significant relationship with water quality parameters. Morphometric characteristics such as depth and age of reservoir as well as type of land use patterns in the watershed was among important parameters for the assessment of water quality characteristics in Korean reservoirs.