• Applied Biological Chemistry
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• v.36 no.6
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• pp.488-494
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• 1993

A photosynthetic bacterium strain P17 having high growth rate and assimilating ability of organic acids was isolated from several soil samples, which was identified as Rhodospirillum rubrum. Cultural conditions of the strain P17 were examined for the production of starter culture used in the treatment of organic waste water. The addition of organic acids mixture as carbon source containing 0.2% Na-acetate, 0.1% Na-propionate and 0.2% Na-lactate and 0.1% of yeast extract as growth factor stimulated the cell growth. The maximal cell production was obtained at $30^{\circ}C$, pH 7.0, 2,500 lux of illumination and $50{\sim}100\;rpm$ of agitation. Under the optimal conditions of batch and fed-batch culture systems in a Jar fermentor, 5.17 g/l and 7.93 g/l of cells were obtained after S days of cultivation, respectively. In continuous culture system, the cell productivity was 0.206 g/l/h at a dilution rate of 0.21 $h^{-1}$. When R. rubrum P17 was cultivated in a soybean curd waste water, initial COD level(3,240 mg/l) of the waste water was reduced to 250 mg/l after 4 days of cultivation.

• Korean Journal of Agricultural Science
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• v.32 no.2
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• pp.233-241
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• 2005

The objective of this study was to investigate the effect of odor removal such as $NH_3$, volatile organic acid (VOA) during the pig manure composting using of the Pyroligneous acid liquor (PAL). The odor removal efficiencies were evaluated throughout the dilution rates (${\times}0$, ${\times}100$, ${\times}300$) of PAL. The results of the study are as followings. $NH_3$ content in all treatments (volume 10L) was approximately 8 mg/kg in compost piles on the first day. In the case of control treatment, it was increased by 46 mg/kg within 10 days and was not detected after 25 days. In contrast, those levels in PA-100 and PA-300 treatments were similar values at 38 mg/kg within 6 days and decreased after 15 days. And GC. equipment was used to analyze the volatile organic acids (acetic acid, butyric acid, isobutyric acid, isovaleric aicd, 2,3-methylbutyric aicd, and propionic acid). The concentration of acetic acid and butyric acid were the higher than other VOAs during the initial composting day and sharply declined after 15 days. The VOAs in the control treatment were detected until 40 days, but PA-100 and PA-300 treatments were not measured after 15 days. The PA-100 in all treatments was the most effective treatment for $NH_3$ gas and VOAs reduction during composting. In addition, these studies for the odor reduction in compost manufacture process would have to research on more effective methods for the PAL utilization in agro-biological aspects.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.192-198
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• 2001

The Kyongan Stream and the inlet part of Paltang Reservoir are under significant influence of the effluent of sewage wastewater treatment plant (SWTP) and untreated domestic wastewater (DOW). The fertility of wastewater was evaluated through bioassay using natural phytoplankton population diluted in five levels. The concentrations of $NH_4$, SRP and SRSi were positively correlated with the biomass of phytoplankton. P concentration showed stronger correlation (r = 0.959, p<0.001)than other nutrients. Compared with the initial concentrations, $NH_4$ concentrations in samples from SWTP and DOW decreased 96% and 7%, respectively during the cultivation, and those of SRSi decreased 97% and 60%. However, $NO_3$ concentrations in samples neither showed any particular change nor any increase. Chl-a concentration ranged between $20\;{\mu}g/l$ and $125\;{\mu}g/l$, which maximum value increased up to 83 times. Estimated from the relationship between chl-a and SRP, the P concentration that can maintain the biomass of algae under mesotrophic state (<25\;{mu}g$\;chl-a/l$) was $83\;{mu}g\; P/l$. The volume of flow to maintain this level solely by natural dilution was about $16{\sim}25$ times of in flowing volume in the stream. However, it is not feasible to tap water of such quantity. Therefore, it is imperative to build an advanced sewage wastewater treatment facility that can reduce $NH_4$ and SRP concentrations that promote the growth of phytoplankton in discharged water.

• Journal of Life Science
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• v.21 no.8
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• pp.1156-1162
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• 2011

Equine coital exanthema caused by equine herpesvirus type 3 (EHV-3) is a venereal disease which seriously drops horse reproduction rates. Here, we isolated EHV-3 from infected horses and investigated their biological characteristics. Initial cytopathic effects such as rounding of cells were detected 48 hours post infection of the virus into RK-13 cells. The infected cells were going to detach from the surface of culture flasks 72 hours post infection. The type of isolated viruses from swabbed samples was EHV-3 by PCR analysis. Glycoprotein G (gG) of isolated EHV-3 has a 99.25 percent similarity rate to that of EHV-3 334/74 control strain. The isolated EHV-3 was named Georo strain. Georo strain consisted of four major proteins including 145 kD, 60 kD, 45 kD and 40 kD, as shown by SDS-PAGE analysis. We hope the newly isolated Georo strain of EHV-3 can be used for studying various aspects of Korean equine coital exanthema.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.740-747
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• 2015

This research was performed to evaluate the feasibility of in situ soil flushing for TPH-contaminated soil remediation. It was conducted in batch test as fundamental research for in situ soil flushing. The 30% of initial TPH concentration was removed by shaking only in batch test. The removal efficiency of TPH in case of groundwater as surfactant dilution solution was approximate 2~6% lower than that of distilled water. Mixing ratio of soil to surfactant solution did not practically effect on the TPH removal efficiency. In the experiment of using single or mixed surfactant solution with 0.1~4.0 wt%, Tween-80, SWA-1503, SWA-1503+SDS showed averagely over 80%. It was determined that the optimum surfactant concentration was 0.1 wt% because there was no significant difference between concentrations of 0.1~4.0 wt%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.882-895
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• 1997

Changes in the benthic communities have been studied to investigate the environmental effects before and after the construction of Shihwa Dike in the West coast of Korea. It is suggested that sequential changes in macrofaunal assemblages progressed in two sucressional directions. In the Shihwa lake under the influence of organic enrichment. First, the appearance of 'azoic tone' or 'grossly polluted zone' developed in the area of less than 6 m in depth resulted from the severe dissolved oxygen depletion due to the eutrophication from the increased organic loading. Second, the 'polluted zone' characterized by the proliferation of the opportunistic species in organically enriched area, was found in the vicinity of the industrial discharges and nearby fluvial inputs. This benthic community succession in the Shihwa lake seemed to be caused by the various ecological events such as an eutrophication in this organically enriched environment after construction of the dike and other physico-chemical parameters like salinity and dissolved oxygen in the bottom water, which may be influenced by the irregular surface water discharge and dilution by outer seawater inflow through the water gate of the dike. On the other hand, the benthic communities in the outside of the dike showed that the species richness was more than doubled and the abundance increased almost seven times more than that before the dike construction. This may be a typical characteristics of the initial phase in benthic eutrophication, suggesting that an increased organic input area may have been reponsible for this faunal change in the study area.

• The Korean Journal of Pesticide Science
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• v.15 no.3
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• pp.317-322
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• 2011

A comparative experiment was conducted to investigate the persistence of chlorfenapyr residue and its biological activity to two spotted spider mite, Tetranychus urticae, after treatment of chlorfenapyr suspension concentrate (10% SC) on paprika plants at recommended (2000 times dilution) and double dosage. Biological half-lives of chlorpfenapyr were estimated as 8 and 5 days in leaves and fruits of paprika plants, respectively. While initial deposits of chlorfenapyr residues in leaves at recommended and double dosages were 22.22 and 37.75 ${\mu}g\;g^{-1}$ at the time of application, its residue decreased to 1.56 ${\mu}g\;g^{-1}$ and 3.62 ${\mu}g\;g^{-1}$ at 29 days after treatment, respectively. Residual biological activity of chlorfenapyr SC to T. urticae at recommended dosage lasted for 7 or 15 days on the basis of 24 or 48-hrs mortality test assayed with feeding on excised leaf chlorfenapyr-treated. The control efficacy to the mite showed a good agreement with the persistence of chlorfenapyr residues in leaves.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.117-127
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• 2008

Green algae are important primary producers in aquatic ecosystem, and they are sensitive test species in bioassay. Green algae are broadly used to assess the adverse effects of various chemicals by measuring the inhibition of metabolism, reproduction and survival. In this study, we extensively gathered domestic and foreign toxicity test methods conducted using green algae, which are distributed in Korean water environment. Selected eight domestic green algae were Chlamydomonas reinhardtii, Desmodesmus subspicatus (=Scenedesmus subspicatus), Scenedesmus abundans, Scenedesmus acutus, Scenedesmus quadricauda, Podohedriella falcata (=Ankistrodesmus falcatus), Pseudokirchneriella subcapitata (=Selenastrum capricornutum), and Chlorella vulgaris. Forty four test methods were collected from the standard test ones, government reports, SCI papers and Korean research papers. P. subcapitata and D. subspicatus are the most common test species recommended by the standard test methods. Initial cell density and dilution water were the main differences among the test methods we collected. We proposed the suitable ecotoxicity test methods based on domestic green algae in Korea. This study could be a fundamental basis to establish the ecotoxicity test methods by green algae distributed in Korea.

• Journal of Environmental Science International
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• v.22 no.7
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• pp.787-799
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• 2013

The aim of this study was to investigate the accumulation of metallic elements and the control effect of marine pollution caused by ocean dumping in the sediments at a waste disposal area in the Yellow Sea. In July 2009, concentrations of organic matter and metallic elements (Al, Fe, As, Cd, Cr, Co, Hg, Ni, Mn, Pb, and Zn) were measured in surface sediments at the site. The ignition loss (IL) in the surface sediments showed a mean value of 15.4%, about 1.5 times higher than the mean value of the sediments in the coastal areas of Korea. The chemical oxygen demand (COD) at some disposal sites exceeded 20 mg $O_2/g{\cdot}dry$, which signifies the initial concentration of marine sediment pollutants in Japan. The disposal sites contain higher concentrations of Cr, Cu and Zn than the sediments of bays and estuaries that might be contaminated. The magnitude of both metal enrichment factors (EF) and adverse biological effects suggest that pollution with Cr and Ni occurred due to the dumping of waste in the study area. In addition, the geoaccumulation index (Igeo) showed that the surface sediments were moderately contaminated. By the mid-2000s, when the amount of waste dumped at this site was the highest, the concentration of metallic elements was higher than ever recorded. On the other hand, in 2008-09, the need for environmental management was relatively low compare with the peak. As a result, the quality of marine sediment has been enhanced, considering the effect of waste reduction and natural dilution in the disposal area.

• Journal of the Korean Institute of Gas
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• v.19 no.4
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• pp.22-28
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• 2015

In order to keep the competitiveness of LPG fuel for transportation fuel, the difference in fuel consumption with gasoline and cost for an aftertreatment system should be reduced with continuous development of technology for LPG engine. In the present study, spray-guided type direct injection combustion system, whose configuration is composed of direct injector in the vicinity of spark plug, was employed to realize stable lean combustion. A certain level of nitrogen oxides($NO_x$) emits due to a locally rich mixture regions in the stratified mixture. With the application of EGR system for the reduction of $NO_x$, 15% of $NO_x$ reduction was achieved whereas fuel consumption and hydrocarbon emission increased. By the application of EGR, the combustion speed reduced especially appeared at initial flame development period and peak heat release rates and increasing rates for heat release rate decreased as EGR rate increased due to the dilution effect of intake air.