• Journal of Korean Society on Water Environment
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• v.29 no.6
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• pp.847-851
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• 2013

This study describes the results of an investigation conducted in order to characterize the quantity and quality of individual gray water streams. The highest pollutants concentrations were found in gray water originating from kitchen and laundry with $BOD_5$ concentrations in the order of several hundreds $mgl^{-1}$. In contrast to this, bathroom was regarded as a major contributor of Escherichia coli. Laundry gray water has higher pH, sodium, sulfate, anionic surfactants. Individual gray water types had different contribution to the overall daily discharge and relative pollutants loads. Kitchen, although accounting for only 13% of the total volume, was identified as a major source of microorganisms with Total coliforms, Escherichia coli, Fecal streptococcus taking up 82%, 74% and 54% of their relative daily load, respectively. The laundry gray water, although being responsible for 36% of the total daily discharge, was established as a significant contributor of sodium, sulfate, anionic surfactants and TOC (70%, 72%, 84% and 52%, respectively). But the laundry gray water was a minor source of microorganisms. Bathroom was found to be a major gray water producer, making up 51% of the flow, but constituted less than 50% of the relative daily load in most cases.

• Journal of Environmental Science International
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• v.11 no.4
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• pp.355-360
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• 2002

This study was to analyze the right of wrong of gray-water treatment by applying BPBE electrode cell to the effluence water in the terminal disposal plant of sewage. The results were as follows : The best result was obtained with applied voltage 40V and detention time 6 minutes for the BPBE electrode cell which has the graphite-plate in main electro-de, packing coconut activated carbon. The elimination rate of COD of Al-plate was higher than that of graphite-plate in main electrode. The result of electrolysis for 3 hour in parallel circuit showed the using possibility of gray-water according to each elimination rate : COD 59%, T-N 69 %, T-P 69%. The BPBE electrode cell with the Al-plate in main electrode made the best effect for the elimination of algae in lake water and algae were not occurred in electrolytic water.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.5
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• pp.261-273
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• 2022

In this study, we collect water control valves that have had accidents due to existing cracks, etc. are collected, and propose investigation items for strengthening the valve structural safety evaluation through a series of analyzes from valve specifications to physicochemical properties are proposed. The results of this study are as follows. First, there was a large variation in the thickness of the body or flange of the valves to be investigated, which is considered to be very important factor, because it may affect the safety of the valve body against internal pressure and the flange connected with the bolt nut. Second, 60% of the valves under investigation had many voids in the valve body and flange, etc. and the decrease in thickness due to corrosion was relatively large on the inner surface in contact with water rather than the outer surface. It is judged that the investigation of depth included voids is very important factor. Third, all valves to be investigated are made of gray cast iron foam, and therefore it is judged that there is no major problem in chemical composition. It is judged that the chemical composition should be investigated. Fourth, as a physical investigation item, the analysis of metal morphology structure seems to be a very important factor for nodular cast iron from rather than a gray cast iron foam water valve with a flake structure. As it was found to be 46.7~68.8% of the standard recommended by KS, it could have a direct effect on damage such as cracks, and therefore it is judged that the evaluation of tensile strength is very important in evaluating the safety of the valve.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.2
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• pp.196-206
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• 2000

Methanogenesis and denitrification in an upflow sludge baffled filter (UBF) reactor were studied using glucose as a fermentative substrate. Experiments were carried out to investigate how to reduce ammonification by changing alkalinity and $COD/NO_3-N$ ratio. Characteristics of granular sludges were examined by specifics methanogenic activity(SMA) and specific denitrification rate(SDR) tests. Microstructures of granules were examined using a scanning electron microscopy(SEM). It was found that COD was removed efficiently owing to the diverse microorganisms. In nitrate conversion, not only $COD/NO_3-N$ ratio but also influent alkalinity played important role in the ratio of denitrification and ammonification of nitrate. This reactor achieved over 95% COD and 99% nitrate removal efficiencies when influent contained 4000 mgCOD/L and $700mgNO_3-N/L$ at the hydraulic retention time of 24 hours. As $COD/NO_3-N$ ratio decreased, granular methanogenic activities using acetate and butyrate as substrates increased while activities using propionate and glucose decreased. There were three types in granules according to the surface color; gray, yellowish gray, and black. Gray or yellowish gray-colored granules were composed two layers, which were composed of black inner side and gray or yellowish gray surface substances. SEM illustrated that both were rod-type and cocci-type microorganisms resembling Methanothrix sp. and Methanococci sp. This study showed that by controlling the influent alkalinity and $COD/NO_3-N$ ratio, ammonification and denitrification could be manipulated.

• Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.78-82
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• 2000

The influence of daily water temperature changes on chemiluminescent (CL) response of phagocytes, plasma glucose level and mortality in cultured gray mullet (Mugil cephalus) was investigated. Among three experimental temperature groups, the fish in group I and group II were maintained constantly at $27^{\circ}C$ and $29^{\circ}C$, respectively, and those in group III were suffered daily elevation of water temperature from $27^{\circ}C$ to $29^{\circ}C$ for 5 hours, then restored again to $27^{\circ}C$. After 1 week of maintaining at each experimental tank, the fish in group III showed significantly lower CL peak value (p < 0.01) and higher plasma glucose levels (p < 0.05) than those in group I and group II. The cumulative mortality of group III was $86.9\%$ within 3 days after being subjected to acute handling stress. On the other hand, the cumulative mortalities of group I and group II were $12.5\%$ and $19.2\%$, respectively. In conclusion, gray mullet farms, especially, in the vicinity of thermoelectric power plants should avoid stressing the fish during periods of high water temperature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.5
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• pp.628-636
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• 1999

This work describes the low-resolution spectral modeling of the water vapor, carbon dioxide and their mixtures by applying the weighted-sum-of-gray-gas-gases model (WSGGM) to each narrow band. Proper modeling scheme of gray gas absorption coefficients vs temperature relation is suggested. Comparison between the modeled emissivity calculated from this relation and the 'true' emissivity obtained from the high temperature statistical narrow band parameters is made for a few typical narrow bands. Low resolution spectral intensities from one-dimensional layers are also obtained and examined for uniform, parabolic and boundary layer type temperature profiles using the obtained WSGGM's with several gray gases. The results are compared with the narrow band spectral intensities obtained by a narrow band model-based code with Curtis-Godson approximation. Good agreement is found between them. Data bases including optimized modeling parameters and total and low-resolution spectral weighting factors are developed for water vapor, carbon dioxide and their mixtures. This model and obtained data bases, available from the authors' Internet site, can be appropriately applied to any radiative transfer equation solver.

• Mycobiology
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• v.41 no.3
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• pp.164-166
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• 2013

A Bacillus sp. BS061 significantly reduced disease incidence of gray mold and powdery mildew. To identify the active principle, the culture filtrate was partitioned between butanol and water. The antifungal activity against B. cinerea was evident in the butanol-soluble portion, and active substances were identified as cyclic lipopeptides, iturin A series, by nuclear magnetic resonance spectrometry (NMR) and mass analysis. Interestingly, antifungal activity against powdery mildew was observed in the water-soluble portion, suggesting that cyclic lipopeptides have no responsibility to suppress powdery mildew. This finding reveals that biocontrol agents of Bacillus origin suppress gray mold and powdery mildew through the secretion of different bioactive substances.

• Korean Journal of Remote Sensing
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• v.31 no.4
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• pp.337-346
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• 2015

Water body extraction based on backscatter information is an essential process to analyze floodaffected areas from Synthetic Aperture Radar (SAR) image. Water body in SAR image tends to have low backscatter values due to homogeneous surface of water, while non-water body has higher backscatter values than water body. Non-water body, however, may also have low backscatter values in high resolution SAR image such as Kompsat-5 image, depending on surface characteristic of the ground. The objective of this paper is to present a method to increase backscatter contrast between water body and non-water body and also to remove efficiently misclassified pixels beyond true water body area. We create an entropy image using a Gray Level Co-occurrence Matrix (GLCM) and classify the entropy image into water body and non-water body pixels by thresholding of the entropy image. In order to reduce the effect of threshold value, we also propose Water Body Texture Index (WBTI), which measures simultaneously the occurrence of repeated water body pixel pair and the uniformity of water body in the binary entropy image. The proposed method produced high overall accuracy of 99.00% and Kappa coefficient of 90.38% in water body extraction using Kompsat-5 image. The accuracy analysis indicates that the proposed WBTI method is less affected by the choice of threshold value and successfully maintains high overall accuracy and Kappa coefficient in wide threshold range.

• Solar Energy
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• v.15 no.3
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• pp.91-103
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• 1995

Non-gray radiation with convection in the entrance region of a smooth tube is numerically investigated. The fluid is a mixture of carbon dioxide, water vapor, and nitrogen to simulate combustion products of propane. The flow is assumed to be laminar and hydrodynamically and thermally developing. The P-1 approximation is used to simplify the radiative transfer equation and the exponential wide band model is adapted to model the spectral absorption coefficients of non-gray gas mixture. The bulk mean temperature and Nusselt number variation along the tube axis are shown for several inlet and wall temperature pairs to show the effect of temperature on the heat transfer characteristics. Nusselt numbers for simultaneously developing flow are compared to those for thermally developing flow. In addition, the effect of the mole fraction of the non-gray gases on convective and radiative Nusselt numbers is investigated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.3
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• pp.237-243
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• 1990

For the improvement of the traditional pots which is using purple spirals for fishing webfoot octopus, Octopus Ocellatus GRAY, some experiments are carried out on the color preference in water tank and also operated practical experiment with PVC pots at sea for the comparison on the basis of the above water tank experiment. The results obtained are as follows: 1. The colors which webfoot octopus prefer in water tank or at sea are gray, red and green in order. 2. The catching efficiency of the pots with small spout(dia. 40mm) is better than that of large spout(dia. 50mm). 3. The results of fishing efficiency between PVC pots and purple spirals are shown almost same tendency.