• Journal of Ecology and Environment
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• v.41 no.9
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• pp.271-280
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• 2017

Background: Soil microorganisms play key roles in nutrient cycling and are distributed throughout the soil profile. Currently, there is little information about the characteristics of the microbial communities along the soil depth because most studies focus on microorganisms inhabiting the soil surface. To better understand the functions and composition of microbial communities and the biogeochemical factors that shape them at different soil depths, we analyzed microbial activities and bacterial and fungal community composition in soils up to a 120 cm depth at a fallow field located in central Korea. To examine the vertical difference of microbial activities and community composition, ${\beta}$-1,4-glucosidase, cellobiohydrolase, ${\beta}$-1,4-xylosidase, ${\beta}$-1,4-N-acetylglucosaminidase, and acid phosphatase activities were analyzed and barcoded pyrosequencing of 16S rRNA genes (bacteria) and internal transcribed spacer region (fungi) was conducted. Results: The activity of all the soil enzymes analyzed, along with soil C concentration, declined with soil depth. For example, acid phosphatase activity was $125.9({\pm}5.7({\pm}1SE))$, $30.9({\pm}0.9)$, $15.7({\pm}0.6)$, $6.7({\pm}0.9)$, and $3.3({\pm}0.3)nmol\;g^{-1}\;h^{-1}$ at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively. Among the bacterial groups, the abundance of Proteobacteria (38.5, 23.2, 23.3, 26.1, and 17.5% at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively) and Firmicutes (12.8, 11.3, 8.6, 4.3, and 0.4% at 0-15, 15-30, 30-60, 60-90, and 90-120 cm soil depths, respectively) decreased with soil depth. On the other hand, the abundance of Ascomycota (51.2, 48.6, 65.7, 46.1, and 45.7% at 15, 30, 60, 90, and 120 cm depths, respectively), a dominant fungal group at this site, showed no clear trend along the soil profile. Conclusions: Our results show that soil C availability can determine soil enzyme activity at different soil depths and that bacterial communities have a clear trend along the soil depth at this study site. These metagenomics studies, along with other studies on microbial functions, are expected to enhance our understanding on the complexity of soil microbial communities and their relationship with biogeochemical factors.

• Korean Journal of Construction Engineering and Management
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• v.21 no.4
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• pp.38-49
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• 2020

As the quality of life has been improving, people are getting higher interest and higher expectation for safety. However, the accident rate at the construction site is still high. Therefore, it is urgent to secure the safety at the construction work. Due to the nature of the construction industry, construction sites are directly exposed to the external environment. The possibility of accident occurrence is increased due to various factors such as the always variable processes, the diversity of manpower input, the increase in vulnerable class, and the danger of construction equipment..Particularly, the disasters occurring at the small- or medium-sized construction sites (budget ≤ 12 billion KRW) account for 88.9% of the total disasters at construction sites (73.4% for casualty). It was due to the lack of management caused by the absence of supervisors and insufficient safety measures. Moreover, it is difficult for the small- or medium-sized construction sites to apply basic safety measures such as safety education and safety facility installation by themselves in order to prevent disasters because they don't have sufficient safety organizations. It is because they have relatively less safety personnel and poorer technology system than large-sized construction sites. Therefore, in order to reduce accidents in construction, it is necessary to prevent accidents at the small- and medium-sized construction sites. From this point of view, the objectives of this study were to identify the key risk items causing accidents frequently by analyzing the accidents at construction sites and identifying problems associated with safety management, and to secure the safety at the small- and medium-sized construction sites.

• Korean Journal of Poultry Science
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• v.46 no.3
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• pp.173-183
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• 2019

Based on their virulence, the avian influenza viruses (AIVs) are classified into two pathotypes: low pathogenic avian influenza (LPAI) virus and highly pathogenic avian influenza (HPAI) virus. Among the 16 HA subtypes of AIV, only the H5 and H7 subtypes are classified as HPAI. Some AIVs, including H5 and H7 viruses, can infect humans directly. Six H7 subtype isolates from wild birds of the H7N7 (n=4) and H7N1 (n=2) subtypes were characterized in this study. Phylogenetic analysis showed that eight viral genes (HA, NA, PB2, PB1, PA, NP, M, and NS) of the H7 isolates clustered in the Eurasian lineage, the genetic diversity of which is indicated by its division into several sublineages. The Korean H7 isolates had two motifs, PEIPKGR and PELPKGR, at the HA cleavage site, which have been associated with LPAI viruses. Six H7 isolates encoded glutamine (Q) and glycine (G) at positions 226 (H3 numbering) and 228 of HA, suggesting avian-type receptor-binding specificity. None of the Korean H7 isolates had the amino acid substitutions E627K in PB2 and I368V in PB1, which are critical for efficient replication in human cells. The Korean H7 isolates showed no deletions in the NA stalk region and in NS. These results suggest that the Korean H7 isolates from wild birds are different from the H7N9 influenza viruses isolated in China in 2013, which are capable of infecting humans.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.398-405
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• 2022

The research was based on long-term studies on the major physico-chemical and hydrological factors and zooplankton community dynamics in the Hwang River. We had 341 times survey and collected zooplankton samples in the Hwang River of mid-Nakdong River from 1995 to 2013. We identified 97 zooplankton species, including 77 rotifers, 16 cladocerans, and 4 copepods. The total zooplankton abundance and species diversity were shown distinctive temporal variation (ANOVA, p<0.001). Annual average of zooplankton population density was 58.4±3.2 ind L^-1 (n=341) and the lowest was 17.0±3.8 ind L^-1 (1996, n=20), while the highest was 151.5±32.3 ind L^-1 (2010, n=22). For zooplankton, small rotifer groups(e.g., Keratella sp., Brachionus sp., Trichotria sp.) dominated the study site for 19 years survey. Statistical analysis revealed that there were positive relationships with SiO₂ (p=0.002) and water level (p<0.001) for the high abundance of rotifer community. There were considerable variations both the total cladocerans population and the number of cladocerans' species concerning annual precipitation. Despite the appearance of various zooplankton in the Hwang River, the mean population density remained low. Due to the lateral structures in the Nakdong River, the downstream basin of the Hwang River is inevitably affected. The zooplankton community in our study site is considered to be mainly influenced by external factors that can stably increase and maintain the volume of the water body and internal factors that induce an increase in food sources through the inflow of nutrients into the water body.

• Korean Journal of Environmental Biology
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• v.41 no.2
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• pp.126-137
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• 2023

Paddy fields provide important habitats for biodiversity conservation within the agricultural ecosystem. Their importance is gradually increasing as their ecological value is better understood. Benthic macroinvertebrates dominate paddy fields. They play an essential role in maintaining the biodiversity of paddy ecosystems. This study aimed to analyze characteristics of benthic macroinvertebrate communities and main environmental factors affecting the distribution of golden apple snails (Pomacea canaliculata). Results showed that the diversity index (H') of the benthic macroinvertebrate community was the highest at the Sangju site (St. 12) but the lowest at the Sancheong site (St. 18). Total Dissolved Solids (TDS), salinity, and Electrical Conductivity (EC) values were the highest in Gimhae and Yeongam based on Canonical Correspondence Analysis (CCA). Numbers of P. canaliculata (m-2) were relatively low in Gunsan and Iksan where water temperatures were high. Therefore, changes in geographical characteristics and environmental factors might affect the distribution of P. canaliculata and characteristics of benthic macroinvertebrate communities. Results of this study can be used as primary data for biodiversity conservation and ecosystem service evaluation in agroecosystems.

• Journal of agriculture & life science
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• v.50 no.1
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• pp.73-81
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• 2016

The objectives of this study were to determine the effects of thinning intensity on the changes of vegetation structure in Japanese Evergreen Oak(Quercus acuta Thunb.) stands in Wando-arboretum. The flora were composed of 24 families, 33 genera, and 36species in thinned sites. The dominant layer of control site showed higher number of plant species than that of treatment sites. On the while, the sub-dominant layer, shrub layer, and herbaceous layer treatment sites showed higher number of plant species than control site. According to the analysis of importance value, Q. acuta in the dominant layer, Q. acuta and Camellia japonica in sub-dominant layer, and Camellia japonica in shrub layer showed the highest importance values, respectively. The importance value of Trachelospermum asiaticum was the highest in the herbaceous layer. According to the results, species diversity was higher in descending order of heavy thinning, light thinning, and control. This result could be explained by increased light transmissions from higher thinning intensity than in other treatments. In this context, the results of this study may be useful for selecting appropriate tending methods in terms of forest management and biodiversity conservation.

• The Korean Journal of Mycology
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• v.42 no.1
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• pp.28-33
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• 2014

Various yeasts from wild flowers of Ulleungdo in Gyeongsangbuk-do and Yokjido in Gyeongsangnam-do, Korea were isolated and identified by comparison of nucleotide sequences for PCR-amplified D1/D2 region of 26S rDNA using BLAST. Forty eight yeast strains of twenty two species and sixty yeast strains of twenty five species were isolated from wild flowers of Ulleungdo and Yokjido, respectively. Only seven species were overlapped from the two different islands areas: Cryptococcus albidus, Cryptococcus laurentii, Metschnikowia reukafii, Pichia scolyti, Rhodotorula glutinis, Rhodotorula graminis and Rhodotorula mucilaginosa. Among forty species from two different islands, other thirty three species were restricted to specific collection site suggesting that each area has distinctive yeast flora.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.41-49
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• 2011

This paper introduces a new search model which can retrieve information instantly and easily about a given search word on Internet and control search spaces diversely. In the existing web searches, because the user has to stop his work, run web browsers, connect to special internet sites, and type the search word by keyboard. it is a long way and not a simple way. Also the search result is too much. The user suffers difficulties of multiple searches for different categories such as dictionary, image, video clips, etc. The software implemented in this paper enables for the user to select search word simply at any documents on the screen and make search started by simply pressing CRTL key and left button of the mouse simultaneously. The software is a mash up style using the Open API which is provided by a web site and can be freely available in any other sites. By calling different Open APIs of several web sites, the mash-up software can integrate search functions of many different sites. We evaluate that the software implemented in this paper will be a good reference of mash-up as one with characteristics of easy and instant search, simple result, diversity of search category, and scalability of search functions.

• Journal of Microbiology and Biotechnology
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• v.27 no.10
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• pp.1753-1762
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• 2017

Sea cucumber (Apostichopus japonicus) is a popular seafood source in Asia, including South Korea, and its consumption has recently increased with recognition of its medicinal properties. However, because raw sea cucumber contains various microbes, its ingestion can cause foodborne illness. Therefore, analysis of the microbiota in the whole body of sea cucumber can extend our understanding of foodborne illness caused by microorganisms and help to better manage products. We collected 40 sea cucumbers from four different sites in August and November, which are known as the maximum production areas in Korea. The microbiota was analyzed by an Illumina MiSeq system, and bacterial amounts were quantified by real-time PCR. The diversity and bacterial amounts in sea cucumber were higher in August than in November. Alpha-, Beta-, and Gammaproteobacteria were common dominant classes in all samples. However, the microbiota composition differed according to sampling time and site. Staphylococcus warneri and Propionibacterium acnes were commonly detected potential pathogens in August and November samples, respectively. The effect of experimental Vibrio parahaemolyticus infection on the indigenous microbiota of sea cucumber was analyzed at different temperatures, revealing clear alterations of Psychrobacter and Moraxella; thus, these shifts can be used as indicators for monitoring infection of sea cucumber. Although further studies are needed to clarify and understand the virulence and mechanisms of the identified pathogens of sea cucumber, our study provides a valuable reference for determining the potential of foodborne illness caused by sea cucumber ingestion and to develop monitoring strategies of products using microbiota information.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.1
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• pp.61-74
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• 2002

The purpose of this study is to propose vegetation management devices through analyzing the actual vegetation, flora, plant community structure and soil chemical concentrations in Weolmi urban nature park, Incheon. The actual vegetation of Weolmi Park in various areas is composed of urbanization area(2 types, 25.9%), landscape planting area(4 types, 16.1%), grass and marsh area(5 types, 7.6%) and mountain forest areal(14 types, 50.4%). The flora is composed of 295 taxa with 80 families, 253 species, 35 varieties and 7 formas, and among them there are 16 naturalized plant families, 39 species, 3 varieties. In reflection of size, the number of the species seems high but most of the them are under influence of human disturbance. Nine survey plots of plant community structure are classified into two groups. One is the semi-natural plant community(Prunus sargentii-Acer palmatum, Quercus accutissma-Prunus sargentii, Quercus serrata-Quercus accutissma-Prunus sargentii, Prunus sargentii, and Zelkova serrata-Prunus sargentii) that migrated finn the planting forest to the natural forest and the other is planting forest(Pinus koraienssis-Pinus thunbergii-Abies holophylla-Chamaectparis obtusa, Prunus sargentii, Pinus thunbergii-Alnus firma, Zelkova serrata). The average pH is 4.65 which means the soil acidity is quite high. The concentration of K, Ca, Mg and base saturation is very low. It seems that the environmental pollutants from Incheon Port and industrial plants near by survey site and long-distance transport of air pollutants from China made the soil condition worse. On the basis of the results above, six vegetation management devices are suggested: 1) removing the hazard plants(Pueraia thunbergiana and Humulus japonica), 2) natural landscape management of the middle and long term, 3) increasing species diversity, 4) Robinia pseudoacacia management, 5) keeping the naturalized plants from being distributed any further inside the mountain forest, 6) improving soil acidification.