• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.343-343
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• 2002

This study examines the influence of long-range transport of dust particles and air pollutants on both local/regional DMS oxidation chemistry and the distribution of sulfur compounds at Jeju Island (33.17$^{\circ}$ N. 126.10$^{\circ}$ E) during the Asian dust-storm(ADS) period in April 2001. The atmospheric concentrations of these sulfur species were measured at a ground station on Jeju Island. Korea as Part of the ACE-Asia intensive operation. Three ADS events were observed during the periods of 10-12, 13-14. and 25-26 April. respectively. The concentrations of DMS and CS$_2$ were higher during the ADS period than during the non-Asian-dust-storm (NADS) period. Conversely. a difference in SO$_2$ levels during the ADS period was not distinguishable from those during the NADS period. The diurnal variation pattern of DMS observed was largely different from that in the remote marine boundary layer. DMS loss by NO$_3$ in the atmospheric boundary layer was dominant due to significantly high NOx levels influenced by the long-range transport of pollutants from East Asia to Jeju Island The DMS maximum during the ADS period was observed in the late afternoon. The oceanic fluxes of DMS during the ADS and NADS periods were estimated to be 5.7$\pm$2.3 and 2.9 (+2.8/-1.5) mole m$^{-2}$ day$^{-1}$ . respectively. The contribution of oxidized DMS to SO$_2$ levels at Jeju Island during the study period was found to be insignificant.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.654-660
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• 2003

To evaluate the biological diversity of fish pathogenic streptococci, 35 strains isolated from diseased olive flounder (Paralichtys olivaceus), were analyzed using a random amplified polymorphic DNA (RAPD) technique with the oligonucleotide commercial primer 6 (Amersham Biosciences). Api 20 Strep test, drug resistance and artificial infection were carried out for further characterization of the isolates. RAPD fingerprints showed similar pattern in 25 strains (about $71.4\%$ of 35 isolates) and these strains were designed as RA group 1. Similarities greater than $44\%$ were obtained when the Dice coefficient was applied among the isolates of RA 1. On the other hand, the reference Streptococcus iniae showed a similar RAPD profile to the isolates with similarity levels of $40-93.3\%.$ Rh I was suggested to be the dominant group isolated from olive flounder suffering from streptococcosis. However, the isolates of Rh 1 group were not classified into the same species by the Api 20 Strep identification system. There was no peculiarity in drug resistance patterns of Rh I group isolates against 7 antibacterial agents. However, only 3 of 25 isolates $(0.12\%)$ showed oxytetracycline (OTC) resistance and OTC might be a useful chemotherapeutic agent in controlling the streptococcosis by strains of RA I group in olive flounder. Fish injected intraperitoneally with $10^5$ CFU of an isolate of Rh I and RA III group showed $60\%\;and\;50\%$ accumulative mortality for 20 days, respectively ($20\%$ in control or Rh II). However luther comparative studies about differences in virulence between isolates are needed.

• YAKHAK HOEJI
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• v.39 no.3
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• pp.276-282
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• 1995

Compared to the first and second-generation cephalosporins, the third-generation cephalosporins are remarkably stable against hydrolysis by the $\beta$-lactamases produced by aerobic gram-negative bacilli, such as Enterobacteriaceae. Among these bacteria, the most prevalent plasmid-encoded $\beta$-lactamase is TEM-1 $\beta$-lactamase belonging to class A or group 2b. This enzyme is produced constitutively and is principally active against peniciflins and old cephalosporins rather than third-generafion cephalosporins, carbapenems and mmobactams. However, new TEM type $\beta$-lactamases including TEM-9 and TEM-12 evolved through point mutations in a gene encoding $\beta$-lactamase have been discovered from patients during chemotherapy. These $\beta$-lactamases are known to be capable of hydrolyzing most of the third-generatim cephalosporins. To study the prevalence of $\beta$-lactamases from clinical isolates collected in Korea. the minimal inhibitory concentratims(MICs) of several third-generation cephalosporins against 628 clinical isolates were determined by agar dilution methods, and $\beta$-lactamas-producing bacteria were isolated by use of cefinase disc. By polymerase chain reaction (PCR) method, clinical isolates harboring a gene for TEM type $\beta$-lactamase were identified among the $\beta$-lactamase producing strains. Twentiy three percent of the clinical isolates was resistant to the thirdgeneration cephalosporins, and more than 90% of resistant cells produced various $\beta$-lactamases. TFM type $\beta$-lactamases were dominant in gram-negative bacilli, such as Escherichia coli, Klebsiella pneumoniae, Enterobacter species. These results suggest the necessity of the development of new cephalosporins which are stable against $\beta$-lactamases like TEM.

• Journal of Ecology and Environment
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• v.43 no.4
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• pp.461-468
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• 2019

Background: This study aimed to identify NO₃^--N sources using the stable isotope δ¹⁵N in Chydorus sphaericus (OF Müller), to investigate hydrological characteristics and nutrient states in artificial wetlands near the Nakdong River. Chydorus sphaericus is dominant in wetlands where aquatic plants are abundant, occurring in high density, and is sensitive to wetland water pollution, making it suitable for identification of NO₃^--N sources. Results: NO₃^--N sources for each wetland were strongly dependent on hydrological characteristics. Wetlands with sewage or rainfall/groundwater as their main sources had high levels of NO₃^--N, whereas wetlands with surface water as their main input had comparatively lower levels. Since wetlands with sewage and rainfall/groundwater as their main water sources were mostly detention ponds, their inputs from tributaries or the main river stream were limited and nutrients such as NO₃^--N easily become concentrated. Changes in NO₃^--N levels at each wetland were closely associated with δ¹⁵N of C. sphaericus. Interestingly, regression analysis also showed positive correlation between δ¹⁵N of C. sphaericus and NO₃^--N level. Conclusions: We conclude that the nitrate stable isotope (δ¹⁵N) of C. sphaericus can be used to elucidate the hydrological characteristics of riverine wetlands. This information is important for maintenance and conservation of artificial wetlands at the Nakdong River.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.5
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• pp.885-891
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• 1996

Various problems in fermented fish products have been a major obstacle to manufacture the product in large scale, which is mainly concerned with the food safety. In this review, salt-fermented anchovy was selected to elucidate the characteristics of microorganisms involved in fermentation; thereby, it is suggested for research areas to achieve the quality improvement of tile product. Different microorganisms were involved in fermentation of anchovy. Dominant species were reported to be Bacillus sp., Pseudomonas sp., and Micrococcus sp., other microorganisms were Vibro sp., Clostridim sp., Serratia sp., Achromobacter sp., Streptococcus sp., Breuibacterium sp., Halobacterium sp., Flavobacterium sp., Corynebacterium sp., Acinetobacter sp., Sarcina sp., Staphylococcus sp., Torulopsis sp., and Saccharomyces sp. To standardize the quality of fermented fish products, screening and isolation of promising microorganisms should be carried out to develop different types of products; at the same time, proper sanitation control should be employed to keep the commercial value of the product by prolonging the shelf life.

• Korean Journal of Environment and Ecology
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• v.21 no.5
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• pp.442-448
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• 2007

This study was carried out to assess the improved aspects of ecological conditions in a small stream, where eco-technological restorations such as gabion-crib mattress arrangement and soil-arresting wicker fence work had already been made up to stabilize the physically and ecologically damaged streambank. Six metrics by diatoms including species richness, Shannon diversity, saprobic index by DAIpo, percent sensitive diatoms, percent of Achnanthes minutissima, dominant index were analysed to assess the ecological integrity of small stream. By generalizing the changed values of six metrics on the stream flow from upper point(ST.1) to lower point(ST.3), it was found that the effect value of ecological condition improvement went up to as much as 33.9% on the average. The results suggested that eco-technological restoration treatment applied to this study is considerably effective for preserving the ecological integrity of small stream.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.10
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• pp.888-893
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• 2016

In this study, the solution plasma process was utilized with the aim of degrading synthetic dyes in water at atmospheric pressure. The experiments were conducted in a batch-type reactor consisting of a symmetric wire-wire electrode configuration with rhodamine B (RhB) as the target synthetic dye. The effects of the plasma treatment time and initial dye concentration on the RhB degradation were investigated by monitoring the change in absorbance of RhB solutions. The RhB solutions turned lighter in color and finally colorless with prolonged plasma treatment time, indicating the destruction of dye molecules. The RhB solutions were found to have degraded, following the first-order kinetic process. However, for high initial RhB concentrations, another kinetic process or factor seems to play a dominant role at the initial degradation stage. The fitted first-order rate constant decreased as the initial concentration increased. This result suggests that the degradation behavior and kinetic process of the RhB solution strongly depends on its initial concentration. The RhB degradation is considered to be due to a combination of factors, including the formation of chemically oxidative species, as well as the emission of intense UV radiation and high-energy electrons from the plasma. We believe that the solution plasma process may prove to be an effective and environment-friendly method for the degradation or remediation of synthetic dye in wastewater.

• Korean Journal of Environment and Ecology
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• v.7 no.2
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• pp.241-251
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• 1994

Use impacts on environmental deteriorations were studied on the four major trails and a campsite of Tokyuksan National Park in 1993. The entire width, bare width, maximum depth and slope of trail as the trail condition were significantly greater on the more heavily used trail. Percentages of rock-exposed, deepening, root-exposed points as the deterioration types of trail which were surveyed at the total of 106 points were higher and trail conditions were significantly different from those of non-deteriorated points. On the Paekryon trail, the damaged area more severe than Class 4 reaches about 910$m^2$/km and the use impact and deterioration on campsites were accelerated. The dominant trees of the the upper and lower layer in trail edge vegetation could be Quercus serrata and Acer pseudo-sieboldianum for Paekryon trail, Q. mongolica and Tripterigium regelii for the other trails. A. pseudo-sieboldianum, Q. serrata, Rhus trichocarpa, Fraxinus sieboldiana, Lespedeza maximowiczii, Symplocos chinensis for Pilosa were classified for tolerant species to use impacts.

• Journal of Wetlands Research
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• v.21 no.4
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• pp.298-304
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• 2019

In this paper, the analytical method to derive wind fragility for urban street tree in Korea was shown. Monte Carlo Simulation method was used to determine the probability of failure for urban street tree. This probability result was used to determine wind fragility parameters for four types of tree based on the study of street tree species in urban area in Daegu, Korea. Wind fragility for street tree was presented in terms of median capacity and standard deviation of the natural logarithm of the capacity. Results showed that the dominant factor affecting the probability of failure of tree under wind load was their diameter. Moreover, amongst the four types of tree chosen, the tree with height 7m and diameter 35cm had the lowest probability of failure under wind loading, whereas the tree with height 8m and diameter 30cm could resist the least wind loading. The median failure wind speed for urban street tree with height 7m were 43.8m/s and 50.6m/s for diameter 30cm and 35cm, respectively. Also, for tree with height 8m, their median failure wind speeds were 38.7m/s and 45.4m/s for tree with diameter 30cm and 35cm, respectively.

• Journal of Korea Water Resources Association
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• v.44 no.6
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• pp.487-495
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• 2011

The sampling and measuring methods of root fiber quantity which greatly governs the stability evaluation of a vegetated levee revetment are proposed by this study and the erosion characteristics related to root fiber quantity are analysed by the experiments. The Phragmites Japonica Steud confirmed the dominant species in a vegetated levee revetment and the Zoysinagrass are selected as the experimental vegetations. The characteristics of erosion depth and erosion rate are analysed according to the root fiber quantity and their corresponding regression equations are suggested. The erosion depth and erosion rate highly decrease with root fiber quantity by experimental results which results in great increasing the erosion resistance of a vegetated levee revetment. The corresponding regression equations for both vegetations of the Phragmites Japonica Steud and the Zoysinagrass are suggested with high determination coefficients. The erosion resistance of the Zoysinagrass is better than that of the Phragmites Japonica Steud.