• Economic and Environmental Geology
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• v.40 no.4
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• pp.419-443
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• 2007

Recently, the branch-out of foreign companies into domestic markets through M&A and the opened followed by the Free Trade Agreement(FTA) with America have made the environmental site assessments of specific site more necessary. In this study, through case study of conducting actual environmental site assessment by use of a toolbox approach at a large scale of chemical plant with various contaminants located in a coastal area, the problems of guideline of domestic environmental assessment of soil were complemented. And an efficient and economical assessment was achieved. All six steps such as basic investigation, environmental site history survey, sampling and analysis, installation of monitoring wells and hydrogeological survey, and data interpretation were conducted in this study. All results of document survey, geological lineament analysis, field geology survey of surrounding area, geophysical prospecting of the site, hydraulic conductivity, measurement of groundwater flow rate and direction, sampling and analysis at each step were associated and estimated as an integrated tool box approach. As a consequence of this study, toolbox approaches were very useful techniques for contamination level and site characterization of subsurface media. The given conditions to conduct a basic survey for domestic soil environment assessment of site by use of existing documents, as well as interviews with the owner/manager/user of all adjacent properties and thorough review of all practically reviewable records pertaining to the property and surrounding properties within "Guideline for Soil Environment Assessment" radii are very poor. As a result, the application of toolbox approach in the environment site assessment of site is not only more efficient and economical, but also could be very useful assessment to integrate the soil and groundwater contamination.

• Journal of radiological science and technology
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• v.37 no.1
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• pp.15-20
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• 2014

This study was to evaluate clinical feasibility of biodegradable polymeric membrane for interventional procedure in preliminary study. Bio-degradable polymetric membrane was produced into a solution by mixing hyaluronic acid powder with NaOH solution in a heating mantle. Three different concentrations of contrast media (10, 20, and 30 vol%) were added to the produced soluble powder, and vertical agitation was performed for 12 hours at a speed of 100 to 200 rpm at a room temperature. It was freeze dried for 24 hours at a temperature $80^{\circ}C$. Pressure on the freeze dried sample was exerted by a hydraulic press in order to form the freeze dried sample into a membrane. The membrane produced with varying contrast medium concentration was visually examined by a scanning electron microscope and radiographically inspected. Under the visual examination, the higher the concentration of contrast medium, the rougher the surface. Radiographic transparency was similar under all conditions of fluoroscopic radiography, simple radiography, and serial radiography. In conclusion, this preliminary study verified that bio-degradable membrane produced with hyaluronic acid was a material with clinical usability.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.2
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• pp.195-202
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• 2010

The evaluation of organic matters and nutrients removal was investigated for the synthetic wastewater and the high strength of dairy wastewater. Two different systems were performed for this research. System A composing of a single RBC with tapered aeration was fed with the synthetic wastewater for 74 days with 173L/day of influent, 200% of internal return and 100% of sludge return for the period 1 and 2. The feed conditions were maintained 346L/day of influent, 50% of internal return and sludge return for the period 3. The dairy wastewater was introduced to evaluate treatment efficiency for system B composing of dual RBCs and tapered aeration tanks for 50 days of experimental run time, in which hydraulic rates were maintained at the constant ratios of 346L/day, 50% of internal return and 50% of sludge return. The spiral string media made of nylon fibre was attached by Bacillus sp. in RBC for both systems. The specific area of string media was $1.4m^2$/m and biomass was maintained at the concentrations of 23g/m. The synthetic wastewater was supplied by 1,800mg/L of glucose, 500mg/L of $NH_4Cl$, and 500mg/L of $KH_2PO_4$ to system A. The dairy wastewater was supplied to system B from dairy production plant. The average influent concentrations were 1,334mg/L of BOD, 2,014mg/L of CODcr, 160mg/L of T-N, and 12mg/L of T-P in system A. The average influent concentrations of parameters were 1,006 mg/L for BOD, 1,875mg/L for $COD_{cr}$, 51.6mg/L for T-N and 8.9mg/L for T-P in system B. Results indicated that removal efficiencies of BOD and $COD_{cr}$ were more than 90% however, the removal efficiency of T-N was 87%, and that of T-P was 82% for system A. Removal efficiencies were 98.5% of BOD, 91.3% of nitrogen and 89% of phosphorus for system B. The removal efficiencies of organic matters, T-N and T-P were higher in system B than in system A. The effluent quality issued by the stringent national legislations for the discharge of the high strength of dairy products wastewater can be improved using sequential RBCsand tapered aeration reactors rather than a single RBC and tapered aeration reactors with Bacillus sp.

• Journal of Korea Water Resources Association
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• v.40 no.9
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• pp.735-742
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• 2007

In this study, a methodology which is based on segments and minimum outsets to estimate the reliability of a real water distribution system efficiently and accurately is suggested. The current reliability assessment models based on minimum cutset consider a pipe as only area impacted by a pipe failure which incurs underestimation of pipe failure impact. In contrary, the suggested methodology adopts "segment" and "unintended isolation" with the hydraulic pressure failure area to define the actual service interruption area in a water distribution system due to a pipe failure, which is different from the Previous reliability estimating methodologies. In addition, a minimum cutset is defined as a single segment incurring abnormal operating conditions and the success mode approach is used to account for the probability of multiple failure combinations of minimum outsets. The model considers numbers and locations of on-off valves when the service interruption area is defined. Once the methodology is applied to a real water distribution system, it is possible to define actual service interruption areas and using the defined areas, the reliability of the water distribution system is estimated reliably, compared with the previous reliability assessment methodologies.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.126-139
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• 1994

Best-estimate thermal-hydraulic codes, CATHARE2 V1.2 and RELAP5/MOD3, hate been assessed against the BETHSY 6.2 tc six-inch cold leg break loss-of-coolant accident (LOCA) test. Main objective is to analyze the overall capabilities of the two codes on physical phenomena of concern during the small break LOCA i.e. two-phase critical flow, depressurization, core water level de-pression, loop seal clearing, liquid holdup, etc. The calculation results show that the too codes predict well both in the occurrences and trends of major two-phase flow phenomena observed. Especially, the CATHARE2 calculations show better agreements with the experimental data. However, the two codes, in common, show some deviations in the predictions of loop seal clearing, collapsed core water level after the loop seal clearing, and accumulator injection behaviors. The discrepancies found from the comprision with the experimental data are larger in the RELAP5 results than in the CATHARE2. To analyze the deviations of the two code predictions in detail, several sensitivity calculations have been performed. In addition to the change of two-phase discharge coefficients for the break junction, fine nodalization and some corrections of the interphase drag term are made. For CATHARE2, the change of interphase drag force improves the mass distribution in the primary side. And the prediction of SG pressure is improved by the modification of boundary conditions. For RELAP5, any single input change doesn't improve the whole result and it is found that the interphase drag model has still large uncertainties.

• Korean Journal of Remote Sensing
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• v.36 no.2_1
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• pp.103-119
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• 2020

Recently, the rapid redeposition and erosion of rivers artificially created by climate change and the Four Rivers Restoration Project is questionable. According to the revised law in Korea, the river management agency will periodically carry out bed changes surveys. However, there are technical limitations in contrast to the trend of increasing spatial coverage, density and narrowing of intervals. National organizations are interest in developing innovative bed changessurvey techniquesfor efficiency. Core of bathymetry survey is to measure the depth of rivers under a variety of river conditions, but that is relatively more risky, time-consuming and expensive compared to conventional ground surveys. To overcome the limitations of traditional technology, echo sounder, which has been mainly used for ocean depth surveying, has been applied to rivers. However, due to various technical limitations, it is still difficult to periodically investigate a wide range of areas. Therefore, technique using the remote sensing has been spotlighted as an alternative, especially showing the possibility of depth measurement using spectral characteristics. In this study, we develop and examine a technique that can measure depth of water using reflectance from spectral characteristics. As a result of applying the technique proposed in thisstudy, it was confirmed that the measured depth and the correlation and error corresponding to 0.986 and 0.053 m were measured in the depth range within 0.95 m. In the future, this study could be applied to the measurement of spatial depth if it is applied to the hyperspectral sensor mounted on the drone.

• Journal of Korea Water Resources Association
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• v.38 no.7 s.156
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• pp.545-554
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• 2005

The detailed interdisciplinary surveys were conducted on the pattern of habitat use of dominant fishes during the spawning and adult stage. The hydraulic parameters of the depth and velocity, discharge, substrate cover streams, and distribution of fish in the Yeonggang, WiCheon, HoeCheon, GeochangwiCheon, CheongdoCheon, DanjangCheon (the Nakdong River Basin) were measured. The Habitat Suitability Criteria was developed for the two fish species (Zacco Platypus and Zacco Temmincki) and life stages(spawning and adult), habitat conditions (depth, velocity and covet). The Physical Habitat Simulation of the Instream Flow Incremental Methodology was applied to calculate for optimal flow and the ecological flow recommendation was proposed by choosing the largest one in the optimal flow. The ecological flow recommendation was $5.0\;m^3/s{\sim}10.0\;m^3/s$ (e.g., $6.5\;m^3/s$ in the NaeseongCheon). Also, the ecological flow recommendations were compared with the existing ecological flow and flow duration analysis.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.5
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• pp.491-499
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• 2008

It is really urgent to develop wastewater treatment system which is economically efficient, occupies small area for buildup, can be easily operated, discharges small amount of sludge due to the more strict water quality standard, the expensive water and energy cost and so on. This study on treatment of wastewater including nonbiodegadable materials using white-rot fungus biofilm were designed to investigate the submerged type of biofilm, hydraulic retention times, recycle rates, and module turning times. Removal efficiencies of fully exposed biofilm type in atmosphere are similar to submerged biofilm of aeration type. The optimum conditions of white-rot fungus biofilm of fully exposed type in atmosphere are HRT 3$\sim$4 hr, recycle rate 6$\sim$10 Q, module turning times 0.5$\sim$2 times/min. At this time, removal efficiencies of organics were COD$_{Cr}$ 65.0$\sim$69.9%, NBDCOD 70.4$\sim$72.7%, BOD$_5$ 88.8$\sim$90.1%, SS 84.2$\sim$90.4%. Moreover average effluent concentration of BOD$_5$(8.9 mg/L) satisfied water quality standard of heavy water(BOD$_5$ less than 10 mg/L) but concentration of NBDCOD(29.6 mg/L) was higher than water quality standard of heavy water(NBDCOD less than 20 mg/L).

• Korean Journal of Environmental Biology
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• v.36 no.1
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• pp.90-97
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• 2018

This study assessed the effect of ozone to control pathogenic bacteria in inlet water flowing to flounder farms, establishing operational parameters of ozonation at seawater conditions. Hydraulic retention time in a reaction pipeline after ozonation was fixed at 3 minutes in a flow through system. Concentrations of total residual oxidant (TRO) by ozonation were measured according to different ozonation intensities. The oxidant reduction potential (ORP), which is indirect but enables real-time measurement, was measured in relation to TRO values. TRO values were $0.01{\pm}0.01mg\;L^{-1}$ at an ORP range of 320-410 mV, $0.07{\pm}0.02mg\;L^{-1}$ at 600 mV, and $0.16{\pm}0.03mg\;L^{-1}$ at 700 mV. A heterotrophic marine bacteria colony was reduced by 80.6-97.9%, showing the suppression effect of ozonation on total bacteria in inlet water. At an ORP range of 400-500 mV, colonies of heterotrophic marine bacteria, Vibrio spp., and gram negative bacteria were significantly reduced in outlet water from a culture tank with ongrowing flounder (230 g) at a stocking density of $8kg\;m^{-2}$. Especially, Vibrio spp. and gram negative bacteria were seldom found at 400-500 mV. The daily feeding rate was from over 0.7% to total body weight at 300-500 mV, showing better performance than that in the control. The pathogenic bacteria entering the flounder farm were effectively removed when the ORP range to 400 mV or less.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.434-441
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• 2009

The effect of varying sulfate concentration on continuous fermentative hydrogen production was studied using enriched mixed microflora in continuously fed reactor. Glucose was used as a model substrate for carbohydrates, and hydraulic retention time (HRT) was maintained at 1, 0.5, 0.25 day, respectively. Sulfate concentration was 0${\sim}$20,000 mg/L and the operating pH was maintained at 5.5. The experimental results indicate that hydrogen production is not affected by high sulfate concentration and shorter HRT of 0.25 day enhance hydrogen production. At HRT 1, 0.5, 0.25 day, the hydrogen production rate and hydrogen yield were 2.6, 4.6, 9.4 L/day, and 2.0, 1.8, 1.6 mol $H_2$/mol glucose, respectively. Residual sulfate content was 96${\sim}$98, 95${\sim}$97, and 94${\sim}$97% at HRT 1, 0.5, 0.25 day which show that no sulfate reduction occurred in the reactor during the experiments. Results of Fluorescence In Situ Hybridization (FISH) may indicate the presence of HPB (hydrogen producing bacteria) under all experimental conditions. However, SRB (sulfate reducing bacteria) were not found.