• Korean Journal of Microbiology
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• v.45 no.2
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• pp.133-139
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• 2009

A nutrient-concentrating system was operated to retrieve total phosphorus efficiently from a non-point pollution source. Attached bacteria were expected to play an important role in the system. Phosphorous was concentrated by formation of bacterial biofilms on rubberized coconut fiber media of the system. While concentration of total phosphorus (TP) ranged merely 0.12~0.35 mg/L in the stream water, TP levels in pore water and the media were 0.45~0.86 mg/L and 40.91~242.71 mg/kg, respectively. Total bacterial number (TBN) ranged $0.3\sim2.3\times10^6$ cells/ml in stream water, $0.4\sim4.4\times10^6$ cells/ml in pore water and $0.8\sim1.9\times10^9$ cells/g in media. There was a close correlation between TP and TBN. Based on band profiles in DGGE analyses, bacterial communities in the media were different from that in the stream water. Clostridium spp. were abundant in the stream water while Aquabacterium spp. were dominant species in early stages of biofilm formation in the media. The genera predominant in matured biofilms of the media were Clostridium and Enterococcus.

• Korean Journal of Environmental Agriculture
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• v.21 no.3
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• pp.189-196
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• 2002

This study was carried out to evaluate the pollutant removal efficiencies of the advanced drinking water treatment using ozonation process. For raw water, Nakdong River was used. By conducting continuous ozonation experiments, the following results were obtained. Efficiency of water treatment was enhanced with increase in ozone dosage. When ozone dosage of 3 mg/L was used, preozonation ot raw water reduced TDOC, ADOC, A &BDOC and NRDOC as much as 0.6 mg/L, 0.2 mg/L, 0.1 mg/L and 1.0 mg/L, respectively. On the other hand, content of BDOC increased at the level of 0.8 mg/L. Ratio of UV254 absorbance to DOC content by the preozonation with 1, 3 and 5 mg/L dosage were 0.048, 0.044 and 0.037, respectively. In case of postozonation, it were 0.018, 0.015 and 0.012, respectively. When the ratios of consumpted ozone content to 1 mg of initial DOC were 1.5 and 2.3 in preozonation and postozonation treatment, respectively, the highest DOC removal rates of 25% and 32% were obtained by the continuous ozonation.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.59-69
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• 1999

Bacterial population, signal compounds of pollution, bacterial productivity, heterotrophic activity and the activities of extracellular enzymes were analyzed four times from July 1994 to April 1995 at Daejin, Galnam, Pohang, and Ulsan in the coastal area of Bast Sea in order to investigate the state of eutrophication. The population of heavy metal resistant bacteria in Pohang was the highest among all stations. The bacterial populations which could utilize C -P compounds (phosphonate) showed the highest at Pohang that was expected for the industrial and agricultural effluents to inpour. It could be useful as an index of expectation about the influx of industrial sewages and agricultural effluents. The activities of extracellular enzymes for the degradation of organic matter were the highest in the Ulsan Chuyongam, but low in Daejin. These results showed positive relationship with the population of heterotrophic bacteria and bacterial productivity The ratio of poly-P and DNA in Pohang was the highest, and that in Ulsan, Galnam, and Daejin consecutively, corresponding with the distribution of heterotrophic bacteria. In case of the heterotrophic activities, each of the stations gives difference of seasonal variation in heterotrophic activities. Bacterial productivity seemed to be dependent on seasons; the highest in summer and the lowest in fall and winter. These seasonal variations of bacterial productivity seems to be similar with those of heterotrophic bacteria. It is suggested that the state of eutrophication could be evaluated by the criteria of the population sizes and the productivities of microorganisms, the amount of poly-P, heterotrophic activity, the activities of extracellular enzymes, etc.

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.364-373
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• 2009

We evaluated stream health, based on integrative approaches of qualitative habitat evaluation index (QHEI), chemical water quality and the index of biological integrity (IBI) using fish assemblages in Daejeon Stream during August 2004 - October 2007. The QHEI values in this study averaged 78.2 (n=28, range: 47$\sim$124), indicating "fair" condition based on the criteria of US EPA (1993). The highest value was in the headwater site (S1) that was 112 (good), whereas the value in S3, mid and downstream was SS (fair-poor) that was the lowest owing to a disturbance on the bed and an artificial bank. Concentrations of chemical parameters such as BOD, TP and conductivity increased from the upstream to the downstream due to higher inputs of organic matters and nutrients from the urban area. Conductivity and TP showed a dilution of stream water by rainwater during summer monsoon. Analysis of fish compositions showed that total number of species was 24 and Zacco platypus was predominated (82%). The mean IBI was 17 (range: 12$\sim$30) during four years and the IBI values also decreased from S1 to S4. These results indicated that ecological health was degradated distinctly as the stream goes down through the city-center. We concluded that Daejeon Stream running through the city are influenced by chemical impact such as an influx of domestic sewage as well as the quality of habitat.

• Fire Science and Engineering
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• v.28 no.6
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• pp.52-57
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• 2014

The present study suggests the fundamental method for the prediction time of the fire origin by analyzing the combustion phenomenon of inflammable material in the building structure. The heat release rate (HRR) with time variant is evaluated for the interphone as a inflammable material, which is opted from the fire incidents in the stairwell. the fire dynamics simulator (FDS ver. 6.1) is applied in order to analyze the difference of the smoke inflow time to the downstair from the fire event area with various fire pattern. The results show that the maximum inflow time difference for the case of the interphone made from ABS materials is about 4.93 times with the input conditions of heat flux values and the environment in the FDS for the fixed stairwell which composed of total volume $291.3m^3$, floorage $23.3m^2$ and the height of each floor 2.5 m. This research can be practical information for the application method of simulation scheme with experimental data to the fire Identification.

• Economic and Environmental Geology
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• v.22 no.3
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• pp.253-266
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• 1989

The Cu-Pb-Zn-Ag hydrothermal vein type deposits which comprise the Dongil and Dong-cheogogsan mines occur within the Cretaceous sedimentary rocks in the Euiseong Basin of the southern Korean peninsula. The ore mineralization is contained within three stage(I,II and III) quartz and calcite veins. Ore minerals occur as dominant chalcopyrite, galena, sphalerite, tetrahedrite and Pb, Ag, Sb and Bi-bearing sulfosalts. Stage I ore minerals were deposited between $400^{\circ}C$ and $200^{\circ}C$ from the fluid with moderate salinities(7.0 to 4.5 eq. wt. % NaCl). Evidence of boiling suggests pressure of less than 150 bars during stage I mineralization. This pressure corresponds to maximum depths of 650 m and 1700 m, respectively, assuming lithostatic and hydrostatic loads. The data on mineralogy, temperature and salinity, together with information on the solubility of Cu complex, suggest that Cu deposition is a result of boiling coupled with declining temperature from $350^{\circ}$ to $250^{\circ}C$ or declining log $a_{o_2}$(from -29.8 to -35.9 atm.)and increasing in pH. Pb, Ag, Sb and Bi-bearing sulfosalts were deposited by cooling and dilution at temperature of less than $250^{\circ}C$ from the ore fluid with less than -35.9 atm. of log $a_{o_2}$.

• Korean Journal of Environmental Agriculture
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• v.10 no.1
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• pp.67-75
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• 1991

The QUAL-II E Model was applied to predict the water quality of the Mankyong drainage System, and lead to following conclusion. 1. The difference between computed and measured BOD at the M-3 (Bakgugeong) station was within 10%, indicating that the application of the QUAL-IIE Model for the prediction of water quality was satisfactory thus far. 2. The application of the model states that the discharge of concentrated pollutants at the M-1 station on the Jeonju stream, located 41Km upstream from the estuary, causes the worst problems. The sluice which extends residence time and enlarges watery surface improves water quality by a Self-purification process at the M-3 station, 28km upstream from the estuary. 3. The accuracy of the model diminished when this model was applied on the estuary downstream of the sluice. Hence, the application of the model on the estuary needs to be used with caution. 4. Among the conputed water quality parameters, BOD is the worst problem. At the M-3 station, BOD is computed to be 26.6 mg/1 in 1996, 30.7 mg/1 in 2,001, 33.0 mg/l in 2006, and 37.5 mg/1 in 2011. When preventive measures against water pollution are not properly exercised, severe problems in irrigation and water resources are expected. This study will be of used in the selection of irrigation water intake points, the criteria of effluent treatment, the management of water resources, and the establishment of water quality managemont policy.

• Journal of Conservation Science
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• v.32 no.4
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• pp.521-534
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• 2016

Ancient tombs are typically comprised of confined rooms, which have different spatial characteristics than the external environment because they are covered by heavy layers of soil. In this study, we examined the thermal energy flow from the outside to inside of Songsan-ri tomb No. 6. External heat flows slowly to the inside because of heavy soil layer, and the presence of several rooms and entrances. For this reason, it takes about two months for the air temperature to travel from the outside to the inside of the tomb. Interestingly, the gradational inflow of thermal energy from outside the tomb leads to delicate horizontal and vertical variations in the wall temperature. These micro-environmental differences occur in the inner tomb every year, so we can expect them to cause condensation with regularity. In addition, we show that the previously installed forced circulation air conditioning system risks fatal damage to the mural wall painting. The results of this research suggest an optimal air conditioning system and optimized space planning to conserve Songsan-ri tomb No. 6 and its mural painting.

• Journal of Radiation Protection and Research
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• v.32 no.2
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• pp.79-88
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• 2007

When an accident occurs at nuclear power plant and radionuclide material is released to the area around the plant, public evacuation is considered as a measure to protect the safety of the residents nearby. This study draws factors required to estimate evacuation time and make estimation of the time to evacuate all residents from the EPZ of Wolsong site in consideration of traffic condition in the neighborhood and on the basis of field data around the site for each factor. The traffic capacity and the traffic volume by season were investigated for the traffic analysis and simulation within EPZ of Wolsong site. As a result, the background traffic volume by season were established. To estimate TGT(Trip Generation Time), the questionnaire surveys were carried out for resident and transient. The TSIS code was applied to traffic analysis in the events of daytime/night and normal/adverse weather under normal day/summer peak traffic condition. The results showed that the evacuation time required for total vehicles to move out from EPZ took generally from 118 to 150 minutes. The evacuation time took longer maximum 17 minutes at night than daytime during summer peak traffic.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.1-10
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• 2000

An experimental study regarding the effect of emulsions on RO is presented. Heavy oil was added to the sea water and the distilled water separately and treated for 30 minutes by a homogenizer to make emulsions. For the case of the sea water without heavy oil the permeate decreased from the beginning of the experiment. Chloride and conductivity increased with time, due to the fouling occurring as the suspended solids in the sea water accumulated on the membrane surface. Rejection rate of salt was 99.6~99.7%. As for the sea water containing heavy oil, the permeate decreased slowly from the beginning of the experiment. This result was the same for the case of the sea water only. However. chloride and conductivity increased significantly when heavy oil was added. In the second experiment with sea water containing heavy oil, the operation time of RO was reduced considerably. With addition of oil, the chloride increased greatly, while the permeate reduced comparatively. In the experiment where emulsion of $0.3{\sim}0.8mg/{\ell}$ was supplied to RO. oil concentration was about 10ppb in the permeate at the end of the experiment. In case of the distilled water containing heavy oil. the conductivity increased. However. the permeate reduced to 30% compared to the case of the sea water containing heavy oil. The case of sea water containing heavy oil showed an opposite result, but the effect of the addition of oil on RO was significant. Oil caused fouling of the RO and the contamination of the whole system, and as the result the system could not be operated properly. As a result the membrane capacity, the amount and water quality of permeate deteriorated significantly.