• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.117-128
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• 2010

The water qualities of Namdae-stream, Yeongok-stream and Sacheon-stream were examined, by using physicochemical factors, trophic status and epilithic diatoms from May 2008 to February 2009. The physicochemical water qualities of three streams were, except for some construction areas and sites of downstream, generally good, having less concentration than BOD of $2\;mg\;L^{-1}$. As for the sites of downstream, there were ongoing pollution such as graduation of nutrients in Namdae-stream and Sacheon-stream, due to salinity of seawater and topographical feature of the closed estuary. The examination of trophic status of Namdae-stream showed mesotrophic status in all the sites. Also, eutrophication was in progress as from the upstream to the downstream of Yeongok-stream, and Sacheon-stream showed eutrophic status in all its sites. As a result of the biological water quality assessment, Namdae-stream, excluding the downstream site, came out to be $\beta\sim\alpha$-oligosaprobic, and biological water quality was good, having TDI less than 50. Some construction sites and downstream site of Namdae-stream are $\beta$-mesosaprobic, and with the TDI over 70, the biological water quality assessment came out to be polluted. Yeongok-stream is $\beta\sim\alpha$-oligosaprobic, and its biological water quality is good, having TDI less than 40. Sacheon-stream, excluding the upstream site on May 2008 and February 2009, is $\beta\sim\alpha$-mesosaprobic, and its TDI over 70 shows that it has been polluted. The correlation analysis showed a high correlation in both DAlpo and TDI. Also, biological assessment of water quality (DAIpo, TDI) showed higher correlation with TSI rather than BOD.

• Korean Journal of Environmental Agriculture
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• v.2 no.1
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• pp.24-29
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• 1983

The effects of temperature on the uptake of $^{137}Cs$ from seawater and on the retention after its uptake by the clam Cycling sinensis was investigated under laboratory conditions. The clams exhibited a greater bioaccumulation of $^{137}Cs$ in $25^{\circ}C$-acclimated animals than those acclimated at $15^{\circ}C$. The viscera of the clams reached the highest bioconcentration factor after 14 days uptake from seawater, but the tissue distribution pattern of $^{137}Cs$ was little influenced, if any, by the uptake temperature. The uptake rate slightly decreased with an increase of temperature in order of $10^{\circ}C$. The radionuclide accumulated in clams was released again in a radionuclide-free seawater according to a two-exponential compartment model. A temperature increase of $10^{\circ}C$ reduced the biological half-life of the long-lived component with a factor of about two, whereas it caused no change in the short-lived component.

• Clean Technology
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• v.14 no.1
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• pp.7-13
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• 2008

RPSA (Rapid Pressure Swing Adsorption) is a cyclic process which can be used to separate gas mixtures by adsorption method. Oxygen which is separated from air is used to the medical oxygen generator and biological wastewater treatment process. RPSA uses only one adsorption bed, so it is very simple to operate compared to conventional PSA process. In this work experimental parameters were examined with RPSA setup and parameters for the oxygen separation from air were obtained.

• Korean Journal of Environmental Biology
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• v.17 no.2
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• pp.129-138
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• 1999

Chlorinated aromatic compounds are one of the largest groups of environmental pollutants as a result of world-wide distribution by using them as herbicides, insecticides, fungicides, solvents, hydraulic and heat transfer fluids, plasticizers, and intermediates for chemical synthesis. Because of their toxicity, persistence, and bioaccumulation, the compounds contaminated ubiquitously in the biosphere has attracted public concerns in terms of serious influences to wild lives and a human being, such as carcinogenicity, mutagenicity, and disturbance in endocrine systems. The biological recalcitrance of the compounds is caused by the number, type, and position of the chlorine substituents as well as by their aromatic structures. In general, the carbon-halogen bonds increase the recalcitrance by increasing electronegativity of the substituent, so that the dechlorination of the compounds is focused as an important mechanism for biodegradation of chlorinated aromatics, along with the cleavage of aromatic rings. The removal of the chlorine substituents has been known as a key step for degradation of chlorinated aromatic compounds under aerobic condition. This can occur as an initial step via oxygenolytic, reductive, and hydrolytic mechanisms. The studies on the biochemistry and genetics about microbial dechlorination give us the potential informations for microbial degradation of xenobiotics contaminated in natural microcosms. Such investigations might provide biotechnological approaches to solve the environmental contamination, such as designing effective bioremediation systems using genetically engineered microorganisms.

• Korean Journal of Organic Agriculture
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• v.27 no.1
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• pp.65-76
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• 2019

Bacillus genus are found abundantly in various sites and their secondary metabolites were used as potential agents in agriculture, notably plant growth promoting and bio-control. The objective of this study was to develop the culture conditions of GH1-13 strain including higher cell growth, stable endospore-forming and enhancement of potential agents which are related with plant growth promoting and phytopathogen suppression. The optimal carbon and nitrogen sources were determined by glucose and soy bean flour, respectively, then resulted in $7.5{\times}10^9cells/mL$, $6.8{\times}10^9\;endospore\;cells/mL$ and sporulation yield of 90% after 30 h cultivation in 500 L submerged fermenter at $37^{\circ}C$, pH 7.0. Cells and cell-free supernatant of GH1-13 strains showed the potent antifungal activity against phytopathogenic fungi of Colletotrichum gloeosporioides. It was also confirmed that indole-3-acetic acid (IAA) production of GH1-13 strain was greatly increased by addition of 0.3% tryptophan.

• Research in Plant Disease
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• v.28 no.4
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• pp.195-203
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• 2022

Zea mays, known as maize or corn, is a major staple crop and an important source of energy for humans and animals, thus ensuring global food security. Approximately 9.4% of the loss of total annual corn production is caused by pathogens including fungi, bacteria, and viruses, resulting in economic losses. Although the use of fungicides is one of the most common strategies to control corn diseases, the frequent use of fungicides causes various health problems in humans and animals. In order to overcome this problem, an eco-friendly control strategy has recently emerged as an alternative way. One such eco-friendly control strategy is the use of beneficial microorganisms in the control of plant pathogens. The beneficial microorganisms can control the plant pathogens in various ways, such as spatial competition with plant pathogens, inhibition of fungal or bacterial growth via the production of secondary metabolites or antibiotics, and direct attack to plant pathogens via enzyme activity. Here, we reviewed microorganisms as biocontrol agents against corn diseases.

• Korean Journal of Microbiology
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• v.42 no.4
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• pp.286-293
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• 2006

Three hundred thirty two bacterial colonies which were able to degrade crude oil were isolated from soil samples that were contaminated with oil in Daejon area. Among them, one bacterial strain was selected for this study based on its low surface tension ability, and this selected bacterial strain was identified as Pseudomonas sp. G314 through physiological-biochemical tests and analysis of its 16S rRNA sequence. Pseudomonas sp. G314 showed a high resistance to antibiotics such as ampicillin, chloramphenicol, spectinomycin, and streptomycin, and heavy metals such as Li, Cr, and Mn. It was found that the optimal pH and temperature for biosurfactant production of Pseudomonas sp. G314 were pH 7.0 and $30^{\circ}C$, respectively. After seven hours of inoculated, the biosurfactant activity reached the maximum, and surface tension of the culture broth was decreased from 72 to 25 dyne/cm. The crude biosurfactant was obtained from the culture broth by acid precipitation, followed by solvent extraction, evaporation and then freeze drying. The CMC (critical micelle concentration) value of the crude biosurfactant was 20 mg/L.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.49-55
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• 2008

White Spot Syndrome Virus (WSSV) is one of the most virulent viral agents in the penaeid shrimp culture industry. In this study, WSSV in a Fenneropenaeus chinensis shrimp farm and an adjacent seawater were concentrated using a membrane filtration and quantified using the quantitative real-time PCR (QRT-PCR) method with newly designed primers and Taqman probe. Sensitivity of primers and probe was proven by WSSV standard curve assay in QRT-PCR. In order to demonstrate the relationship between WSSV and environmental parameters, physicochemical and biological parameters of the farm and influent seawaters were monitored from June to September, 2007. The abundance of WSSV ranged 3,814-121,546 copies per 1 liter of seawater, which was correlated with fecal enterococci ($r^2=0.9$, p=0.02), chlorophyll ${\alpha}$ ($r^2=0.8$, p=0.03) and $BOD_5$ ($r^2=0.8$, p=0.07). Subsequently, it is concluded that the QRT-PCR method using Taqman probe established in this study was efficient to clarify the quantification of WSSV in seawaters. Statistical analyses of environmental parameters obtained in this study also showed that the abundance of WSSV was correlated with several biological parameters rather than physicochemical parameters.

• Research in Plant Disease
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• v.27 no.4
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• pp.129-136
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• 2021

Rice is responsible for the stable crop of 3 billion people worldwide, about half of Asian depends on it, and rice is grown in more than 100 countries. Rice diseases can lead to devastating economic loss by decreasing yield production, disturbing a stable food supply and demand chain. The most commonly used method to control rice disease is chemical control. However, misuse of chemical control can cause environmental pollution, residual toxicity, and the emergence of chemical-resistant pathogens, the deterioration of soil quality, and the destruction of biodiversity. In order to control rice diseases, research on alternative biocontrol is actively pursued including microorganism-oriented biocontrol agents. Microbial agents control plant disease through competition with and antibiotic effects and parasitism against plant pathogens. Microorganisms isolated from the rice rhizosphere are studied comprehensively as biocontrol agents against rice pathogens. Bacillus sp., Pseudomonas sp., and Trichoderma sp. were reported to control rice diseases, such as blast, sheath blight, bacterial leaf blight, brown spot, and bakanae diseases. Here we reviewed the microorganisms that are studied as biocontrol agents against rice diseases.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.121-123
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• 1999

Bio-Aerosol Concentrator Inlets were made to collect particles of which size was $2\mu\textrm{m}$ as aerodynamic diameter or larger. The Concentrator Inlets were designed by using virtual impactors, because the virtual impactors are known for high efficiency. In a virtual impactor, the intake air is typically divided into two streams with the major and the minor flow. In this work, several types of the acceleration nozzles and collection probes were designed. Subsequently, the results were evaluated experimentally. It was found that if controled properly, the velocity can improve substantially the aerosol concentration performance. The diameter of acceleration nozzle and type of collection probe were varied to obtain the optimum design. Subsequently, the different designs were compared respectively and the best design among them was identified. It is expected that this new finding can help improve design of future Aerosol Concentrator for high concentration rate.