• The Korean Journal of Zoology
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• v.34 no.2
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• pp.257-264
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• 1991

Studies on the geographical distribution and the seasonal prevalence of chigger mites, with particular reference to L. paflidum, a vector species of tsutsugamushi disease were carried out during the period of July 1989-October 1990. From total 111 field rodents collected during the study period, 4,498 chiggers were obtained and 12 species of 4 genera were identified. L. paflidum, the vector species was the dorninant species, showing 65.6% of the total chiggers. L. scutellare, known as the important vector species of tsutsugamushi disease in Japan was not found in the study area, except Yesan-gun, Chungcheong-namdo where only one specimen was collected. The distribution of chigger mites was clearly localized by species, showing the different dominant species by locality. The population density of L. paflidum was high at two study areas, moderate at one area and very low at six other areas, compared to the other species. The study on seasonal prevalence of L. paflidum population density resulted that they started appearing in September (9.8%), showed the peak in October (45.4%) and November (30.6%), almost disappeared during the period of December-March (1.3-0%), reappeared in April (12.7%) showing a small peak, and again almost disappeared until September. L. palpafe was appeared only in winter and spring (December-April).

• Journal of Korean Society on Water Environment
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• v.28 no.5
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• pp.743-753
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• 2012

The hydrologic models, capable of simulating groundwater recharge for long-term period and effects on it of crops management in the agricultural areas, have been used to compute groundwater recharge in the agricultural fields. Among these models, the Soil and Water Assessment Tool (SWAT) has been widely used because it could interpret hydrologic conditions for the long time considering effects of weather condition, land uses, and soil. However the SWAT model couldn't represent the spatial information of Hydrologic Response Unit (HRU), the SWAT HRU mapping module was developed in 2010. With this capability, it is possible to assume and analyze spatio-temporal groundwater recharge. In this study, groundwater recharge of rate for various crops in the Mandae stream watershed was estimated using SWAT HRU Mapping module, which can simulate spato-temporal recharge rate. As a result of this study, Coefficient of determination ($R^2$) and Nash-Sutcliffe model efficiency (NSE) for flow calibration were 0.80 and 0.72, respectively, and monthly groundwater recharge of Mandae watershed in Haean-myeon was 381.24 mm/year. It was 28% of total precipitation in 2009. Groundwater recharge rate was 73.54 mm/month and 73.58 mm/month for July and August 2009, which is approximately 18 times of groundwater recharge rate for December 2009. The groundwater recharges for each month through the year were varying. The groundwater recharge was smaller in the spring and winter seasons, relatively. So, it is necessary to enforce proper management of groundwater recharge during droughty season. Also, the SWAT HRU Mapping module could show the result of groundwater recharge as a GIS map and analyze spatio-temporal groundwater recharge. So, this method, proposed in this study, would be quite useful to make groundwater management plans at agriculture-dominant watershed.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.757-763
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• 2006

In our previous studies, we have isolated bacteria from BTEX-contaminated sediment, which utilized BTEX as a sole carbon source and $NO_3$-N as an electron acceptor. For the possibility of field application, we have applied co-culture of those isolates in the BTEX-contaminated soil and evaluated their biodegradation efficiencies. To investigate the relationship between the isolates and indigenous microorganism in soil, changes of microbial community structure in soil samples with respect to time were monitored. To examine this, soil samples were artificially contaminated with benzene, toluene, ethylbenzene and o-xylene. BTEX-degrading bacteria such as Pseudomonas stutzeri strain 15(DQ 202712), Klebsiells sp. strain 20(DQ 202715) and Citrobacter sp. strain A(DQ 202713) were injected into the soil samples in the ratio of 2:1:1. Our results showed that the highest BTEX biodegradation efficiency was achieved when both BTEX and $NO_3-N$ existed simultaneously. The change in soil microbial community structure was characterized by PCR-DGGE analysis comparing the relative DGGE band intensities. The band intensities of indigenous microorganisms in the soil were reduced by injecting co-culture of the three isolates. On the contrary, the relative band intensities of the isolates were increased. Among the three isolates, Pseudomonas stutzeri strain 15 rendered the highest band intensity. This indicates that the Pseudomonas stutzeri was the dominant microbial species found in the soil samples.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.151-157
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• 2005

A one-dimensional numerical model was developed to simulate vertical profiles of electron acceptors and their reduced species in benthic sediments. The model accounted for microbial degradation of organic matter and subsequent chemical reactions of interest using stoichiometric relationships. Depending on the dominant electron acceptors utilized by microorganisms, the benthic sediments were assumed to be vertically subdivided into six zones: (1) aerobic respiration, (2) denitrification, (3) manganese reduction, (4) iron reduction, (5) sulfate reduction, and (6) methanogenesis. The utilizations of electron acceptors in the biologically mediated oxidation of organic matter were represented by Monod-type expression. The mass balance equations formulated for the reactive transport of organic matter, electron acceptors, and their corresponding reduced species in the sediments were solved utilizing an iterative multistep numerical method. The ability of model to simulate a freshwater sediments system was tested by comparing simulation results against published data obtained from lake sediments. The simulation results reasonably agreed with field measurements for most species, except for ammonia. This result showed that the C/N ratio (106/16) in the sediments is lower than what the Redfield formula prescribes. Since accurate estimates of vertical profiles of electron acceptors and their reduced species are important to determine the mobility and bioavailability of trace metals in the sediments, the model has potential application to assess the stability of selected trace metals in the sediments.

• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.976-986
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• 2018

Knowledge about the gut bacterial communities associated with insects is essential to understand their roles in the physiology of the host. In the present study, the gut bacterial communities of a laboratory-reared insecticide-susceptible (IS), and a field-collected insecticide-resistant (IR) population of a major rice pest, the brown planthopper Nilaparvata lugens, were evaluated. The deep-sequencing analysis of the V3 hypervariable region of the 16S rRNA gene was performed using Illumina and the sequence data were processed using QIIME. The toxicological bioassays showed that compared with the IS population, IR population exhibited 7.9-, 6.7-, 14.8-, and 18.7-fold resistance to acephate, imidacloprid, thiamethoxam, and buprofezin, respectively. The analysis of the alpha diversity indicated a higher bacterial diversity and richness associated with the IR population. The dominant phylum in the IS population was Proteobacteria (99.86%), whereas the IR population consisted of Firmicutes (46.06%), followed by Bacteroidetes (30.8%) and Proteobacteria (15.49%). Morganella, Weissella, and Enterococcus were among the genera shared between the two populations and might form the core bacteria associated with N. lugens. The taxonomic-to-phenotypic mapping revealed the presence of ammonia oxidizers, nitrogen fixers, sulfur oxidizers and reducers, xylan degraders, and aromatic hydrocarbon degraders in the metagenome of N. lugens. Interestingly, the IR population was found to be enriched with bacteria involved in detoxification functions. The results obtained in this study provide a basis for future studies elucidating the roles of the gut bacteria in the insecticide resistance-associated symbiotic relationship and on the design of novel strategies for the management of N. lugens.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.90-95
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• 2009

Sludge pre-treatment utilizing cavitation is one of the commercialized methods at present. Cavitation can be generated by two different methods, sonotrode and hydrodynamic principle, and there has been no direct comparison between the two methods. In this study, solubilization efficiency, changes in sludge size distribution, and the methane production potential after pre-treatment by the two methods were compared. The maximum solubilization efficiency per unit energy input with the two methods was similar, and was 302 mg ${\Delta}SCOD/g$ TS at the energy input of 0.18 kWh/L. Break-up of sludge flocs were dominant during the early period of pre-treatment, while cell disintegration continued through the pre-treatment with the increase in the number of particles with less than 1 ${\mu}m$. BMP test results indicated that the methane potential increased up to 24.3% without differences between the two pre-treatments, and the increase in methane potential did not proportional to energy input. Although the energy efficiency of the two methods was quite similar, hydrodynamic methods might be a better choice for field application considering the operation and maintenance cost, and its potential improvement in energy efficiency.

• Child Health Nursing Research
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• v.7 no.1
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• pp.85-95
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• 2001

The purpose of this study was to reveal what influences the divergent methodological researches have brought the nursing practice in during the past 3 decades. The nursing record sheets ie, the nursing discourses were analyzed to know the knowledges that were recorded, accepted and communicated in nursing practice at pediatric intensive care units, and unclosed the philosophical and methodological position of that knowledges. The texts were 13 sheets, 3 kinds of nursing record(7 24hours flow charts, 4 nursing information record sheets and 2 transfer record sheets) used at 4 hospitals. The unit of analysis was 'word'. First, all words of the sheets were listed up, clustered into categories based on their contents. And then, the larger conceptual themes were drawn to elucidate the effect of the knowledge/power and the philosophical and methodological position of that knowledges. To enhanced the validity of the analysis, the data were analyzed by two researchers. The 'words' were classified into 3 categories; 'general information', 'assessment' and 'inter-vention'. The conceptual themes of the texts were 'the gaze for quantification and objectification' and 'technical/assimilated caring'. This themes reflected the logic positivistic and biomedical view that had dominated at clinical practice. Nursing has endeavored to resist the logic-positivistic knowledge/power and to established the nursing knowledge/power based on multiple philosophies and methodologies, especially phenomenological-interpretative. But the results of this study revealed that such efforts in nursing theory and research couldn't influenced the knowledge of practice. Logic positivism was yet so strong and the biomedical model yet dominated in the clinical practice. It identified that the borrowed theory and the knowledge from the received view gave nursing the power. But they were modalities that reinforced the dominant, medical power. Nursing has investigate the other positions (feminism, Habermas' critical social theory and Foucault's discourse theory). This positions suggest different assumptions but share the common concepts; equality, emancipation and freedom. The important point is how make these concepts the practical for nursing knowledge/power in practice. We must recognize that the praxis at clinical setting take place at the field unlike theoretical praxis. The change of clinical practice is the social, economic and political change.

• Journal of the Korean Geographical Society
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• v.39 no.6 s.105
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• pp.873-887
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• 2004

We examined research trends in geomorphology and hydrogeography in America based on papers presented at the annual meetings of the Association of American Geographers(AAG) and papers published in two AAG journals between 2002 and 2004. Among the 437 papers in geomorphology, $40\%$ of the papers concerned fluvial geomorphology, followed by environmental geomorphology and glacial and periglacial geomorphology concern. Among the 452 papers in hydrogeography, about $20\%$ of the papers focused on water, law and institutional aspects, followed by hydrogeomorphology and hydrologic modeling. Twenty one papers examining geomorphology and hydeogeography were published in two AAG journals, and fluvial geomorpholoy was the dominant theme. GIS was used for $29\%$ papers in geomorphology and $35\%$ of papers in hydrogeography($35\%$), suggesting that other methods, including geostatistics, field survey, and qualitative methods, are employed as well. This methodological diversification seems to be associated with solving such complex environmental problems as integrated watershed management and implies that geomorphologists and hydrogeographers are expanding their traditional territories and are making close connections with human-environment geographers and human geographers. Geomorphologists and hydrogeographers are likely to continue examining the causes of and solving environmental problems that humans are currently facing and might face in the future.

• Korean Journal of Environment and Ecology
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• v.26 no.1
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• pp.1-10
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• 2012

The habitats characteristics of Polypodium vulgare L. in Ulleung-do were investigated to compile basic data for conservation and restoration. Natural habitats were located at altitudes of 410~748m with inclinations of $12{\sim}80^{\circ}$. Sixty six vascular plants were identified from 10 quadrats in 4 habitats. Dominant species among the woody plants, based on importance value, were Acer pictum subsp. mono(49.52%) in the tree (T1) layer, Sorbus amurensis(28.99%) in the subtree (T2) and Schizophragma hydrangeoides(51.99%), Ligustrum foliosum(8.82%), Fagus engleriana(7.25%) in the shrub (S) layer. Importance value for members of the herb (H) layer were as follows: Polypodium vulgare 23.23%; Maianthemum dilatatum 9.65%; Phryma leptostachya var. asiatica 9.23%; Dryopteris crassirhizoma 8.40%; Carex shimidzensis 6.75% and Dystaenia takesimana 5.42%. The importance value of the last five species were high, so they were at affinity with Polypodium vulgare in their habitats. Species diversity was 1.18, and dominance and evenness were found to be 0.11 and 0.84, respectively. The soil types were sandy loam. Average field capacity was 30.42%, and the organic matter and pH were 17.95%, and 4.70. Correlation coefficients based on environmental factors, vegetation and soil analysis were showed that positive correlations between species diversity and species richness, whereas between species diversity and dominance, coverage of Polypodium vulgare and species richness were showed negative correlations.

• Korean journal of applied entomology
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• v.40 no.3
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• pp.211-217
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• 2001

Field survey for Orius spp., predacious natural enemies of thrips pests, on several plants by beating or sweeping method revealed that O. sauteri, O. strigicollis, O. minutus, and O. nagaii habituated in open fields or in greenhouses of Korea. Among them, O. sauteri was the most dominant species at all areas (83.0~92.5%), followed by O. strigicollis and O. minutus. Especially, O. sauteri exclusively dominated on the economically important crops such as soybean, red pepper, and watermelon. On the other hand, O. strigicallis and O. nagaii occurred mainly on ornamental plants including chrysanthemum and rose and on rice, respectively, during summer-autumn season. The seasonal occurrence varied depending on the plant. Initial population of Orius spp. was first observed on white clover in late May, followed by on soybean, red pepper, an buck wheat in early June, indcating that movement of Orius spp. relates to the flowering time of the plant. Peak of Orius spp. abundance was found first in July and secondly in August or September. On white clover and buck wheat the first peak of abundance was one week earlier than on soybean and red pepper. Therefore, we suppose that wild plants such as white clover can serve as a reservoir for Orius spp. after overwintering.