• Journal of Wetlands Research
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• v.1 no.1
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• pp.29-44
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• 1999

Vegetation structure and distribution of the vascular hydrophytes and hygrophytes, and the growth pattern, standing crop and amounts of nutrient uptake by Salix species were investigated in the upper stream wetlands of the Namgang-Dam, Chinju-city, Gyeongsangnam-do, Korea from April to November in 1997. The flora was composed of 43 hydrophytes and 241 hygrophytes, or total 284 vascular plants. The life forms of the hydrophytes were classified as 27 kinds of emergent plants, 4 floating-leaved plants, 3 free-floating plants, and 9 submersed plants. In the herb layer, the dominant species was Persicaria hyciropiper, and the ranges of the species diversity indices (H'), equitabilities, (J') and community similarity indices (CCs) were 1.59~1.89, 0.87~0.96, and 0.35~0.83, respectively. In the shrub and subtree layers, 17 kinds of Salix species were supposed to the pioneer plants at the early stage of the succession. The number of branches per main stem of Salix species was 5.0. The DBH class-frequency histograms of Salix species were the reverse J type, and the natural regeneration of the Salix community was expected. Basal area of Salix species per square meter was $24.87cm^2$. Volume of Salix species per square meter was $12,008cm^3$ and total phytomass of the Salix species was estimated as 12,894 ton. Biomass distribution of Salix species in the stem, the branch and twig, and the leaf was 64.1%, 28.1%, and 7.8%, respectively. The amounts of nitrogen and phosphorus absorbed by Salix species were 68,022 and 19,823 kg. It was recommended that application and conservation of the wetland and other counterplans are indispensable to reduce the adverse effects of water pollution and to preserve the wetland ecosystem.

• Journal of Ecology and Environment
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• v.29 no.6
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• pp.585-591
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• 2006

We measured the litterfall quantity and investigated the nutrient dynamics in decomposing litter for three years at the LTER sites installed in a deciduous broadleaf natural forest in Mt. Gyebangsan, South Korea. Litterfall production was significantly different among the sampling dates, whereas it was not significantly different among the years. The total annual mean litterfall production for three years was 6,593 kg $ha^{-1}$ $yr^{-1}$ and leaf litter accounted for 82.6% of the litterfall. The leaf litter quantity was highest in Quercus mongolia, followed by leaf of other species, Betula schmidtii, Kaplopanax pictus, Acer pseudo-sieboldianum, etc., which are dominant tree species in the site. The mass loss from the decomposition of leaf litter was fastest in Cortinus controversa (100%), followed by A. preudo-sieboldianum, K. pictus, and B. schmidtii. 100% of litter for C. controversa, 96.1% for A. pseudo-sieboldianum, 92.8% for K. pictus decomposed, while 66.2% of litter for Q. mongolia decayed for 1,003 days. The lower rate of the mass loss in the litter of Q. mongolia may be attributed to the difference in substrate quality, such as lower nutrient concentrations compared with those of other tree species. The concentrations of N, P, and Ca for five litter types increased over time, while the concentrations of K and Mg decreased over time. Compared with the nutrients in the litter of Q. mongolia, the nutrients (N, P, K, Ca, Mg) in the litter of other species, C. controversa, A. pseudo-sieboldianum, and K. pictus, were released more rapidly. The results showed that the mass loss and the nutrient dynamics in the litter are variable depending on the tree species even in the same site conditions.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.152-159
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• 2002

The seasonal variations of nitrifying bacterial population sampled from 3 sites in Moon-Chon reservoir were analyzed by in situ hybridization with fluorescently labeled rRNA-targeted oligonucleotide probes from August 2000 until July 2001. In addition, physico-chemical parameters such as temperature, pH, chi-a and DOC were measured to determine correlations between those factors and the size of nitrifying bacterial populations. Total bacterial numbers varied in the range of $0.8{\sim}1.5{\times}10^6\;cells/ml$ independent of sites and had the maximal values in March at all 3 stations. The ratio of eubacteria to total bacteria ranged from 44.9% to 79.5%, and the ratio of each nitrifying bacteria to eubacterial numbers reached only $1.0{\sim}7.4%$. The variations of ammonia-oxidizing bacteria ranged from $1.1{\times}10^4$ to $3.0{\times}10^4\;cells/ml$ without noticeable peak values whereas those of nitrite-oxidizing bacteria varied in $1.3{\sim}5.7{\times}10^4\;cells/ml$ with the increasing tendency in winter regardless of the sites. Moreover it was observed that the numbers of nitrite-oxidizing bacteria were higher than those of ammonia-oxidizing bacteria. Total bacterial numbers correlated with water temperature (r = 0.355, p<0.05) and DOC (r = 0.58G, p<0.01) positively whereas nitrite-oxidizing bacteria correlated with temperature (r = -0.416, p<0.05) and pH (r = -0.568, p = 0.001) negatively. In addition, DOC represented good correlations with eubacterial numbers (r = 0.448, p<0.01). These results indicate that temperature, DOC and pH might be one of the main factors affecting variations of bacterial populations in the aquatic ecosystem. It was also suggested that FISH method is a useful tool for detection of slow growing nitrifying bacteria.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.216-233
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• 2020

This study set out to review tomb culture in the Gyeongju region during the Bronze Age, and also examine the patterns of dolmens during their end phase. For these purposes, the study analyzed 18 tomb relics from the Bronze Age and nine from the early Iron Age. Gyeongju belongs to the Geomdan-ri cultural zone. Approximately 120 tombs from the Bronze Age have been excavated in the Gyeongju region. There are fewer tombs than dwellings in the region, which is a general characteristic of the Geomdan-ri cultural zone. Although the number of tombs is small, the detailed structure of the dead body is varied. During the Bronze Age, tombs in the Gyeongju region were characterized by more prolific construction of pit tombs, dolmens with boundaries, and stacked stone altars than were the cases in other areas. There is a great possibility that the pit tombs in the Gyeongju region were influenced by their counterparts in the northeastern parts of North Korea, given the spindle whorl artifacts buried at the Dongsan-ri sites. Dolmens with boundaries and stacked stone altars are usually distributed in the Songguk-ri cultural zone, and it is peculiar that instances of these are found in large numbers in the Gyeongju region as part of the Geomdanri cultural zone. Even in the early Iron Age, the building of dolmens with boundaries and stacked stone altars continued in the Gyeongju region under the influence of the Bronze Age. A new group of people moved into the area, and they crafted ring-rimmed pottery and built wooden coffin tombs. In the early Iron Age, new rituals performed in high places also appeared, and were likely to provide venues for memorial services for heavenly gods in town-center areas. The Hwacheon-ri Mt. 251-1 relic and the Jukdong-ri relic are ruins that exhibit the aspect of rituals performed in high places well. In these rituals performed in high places, a stacked stone altar was built with the same form as the dolmens with boundaries, and a similar rock to the cover stone of a dolmen was used. People continued to build and use dolmens with boundaries and stacked stone altars while sustaining the Bronze Age traditions, even into the early Iron Age, because the authority of dolmens was maintained. Some dolmens with boundaries and stacked stone altars, known as being Bronze Age in origin, would have continued to be used in ritual practices until the early Iron Age. Entering the latter half of the second century B.C., wooden coffin tombs began to propagate. This was the time when the southern provinces, including the Gyeongju region, were included in the East Asian network, with the spread of ironware culture and the arrival of artifacts from central China. Around this time, dolmen culture faded into history with a new era beginning in its place.

• Journal of Life Science
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• v.31 no.3
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• pp.330-337
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• 2021

This study was conducted to investigate the potential of Stewartia koreana as oral healthcare materials. The antibacterial activity of ethanol extracts from leaves and branches of S. koreana against oral bacteria was confirmed. The leaf and branch extracts (1 mg/disc) showed antibacterial activity against P. gingivalis only among several tested oral bacteria. The leaf extracts showed higher antibacterial activity, with values similar to those of chlorhexidine, which was used as a positive control. The MIC of the leaf extract against P. gingivalis was 0.4 mg/ml and showed bacteriostatic action. The inhibitory effects of the extract on biofilm formation and on gene expression related to biofilm formation by P. gingivalis were determined by biofilm biomass staining, scanning electron microscopy (SEM), and qRT-PCR analysis. The biofilm production rate and cell growth of P. gingivalis in the cultures treated with 0.2-2.0 mg/ml of S. koreana leaf extracts were significantly decreased in a concentration-dependent manner. The inhibitory effect on the formation of P. gingivalis biofilms at concentrations of 1 mg/ml was confirmed by SEM. The qRT-PCR analysis showed concentration-dependent suppression of the fimA and fimB gene expression associated with fimbriae formation in the cultures treated with 0.2-2.0 mg/ml S. koreana leaf extract. These results support the conclusion that S. koreana leaf extracts can be used as oral healthcare materials derived from natural materials, as demonstrated by the antibacterial action and inhibition of biofilm formation of P. gingivalis.

• Journal of Environmental Impact Assessment
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• v.30 no.1
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• pp.35-48
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• 2021

In this study, the assessment of field applicability of in-situ remediation of nitrate-contaminated groundwater located in Yesan-gun was performed. Zero-valent iron/bio composite media injected PRB (Permeable Reactive Barrier) and monitoring well were installed in the contaminated groundwater site and monitored main remediation indicators during the PRB operation. Nitrate, nitrite, ammonia, Fe ion, TOC, and turbidity were analyzed and the diversity and population of microorganism in the PRB installed site were investigated for the verification of effect of injected PRB. In the study site where is an agricultural area, a river flows from west to east that forms a river boundary and the southern area has an impermeable sector. It was found that nitrate flows into the river, which is similar as groundwater flow. Simulation result for the fate of nitrate in groundwater showed steady state of nitrate arrived after 3~5 years passed. However, it is just to consider current conditions with no additional input of contaminant source, if additional input of contaminant source occurs contamination dispersion and time for steady state are expected to be increased. The monitoring results showed that Fe ion, TOC and turbidity in groundwater were not clearly changed in concentration after PRB installation, which indicates adaptability of the injected PRB for remediation of groundwater with no additional harmful effect to water quality. The concentration of nitrate maintained less than 5mg/L until 42 days after PRB installation and recovered its initial concentration after 84 days passed and showed termination of reactivity of injected zero-valent iron/bio composite media for removal nitrate. Nitrite and ammonia ions found after installation of PRB indicates reductive removal of nitrate. And the outstanding increase of microorganism diversity and population of Betaproteobacteria Class which includes denitrification microorganism explains biologically reductive removal of nitrate in injected PRB.

• Korean Journal of Ecology and Environment
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• v.54 no.1
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• pp.24-38
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• 2021

Microhabitat In the upper stream is created by various environment variables such as the bottom substrate and the physicochemical factors, and may influence the distribution of benthic macroinvertebrates. We investigated the bottom substrate and environmental variables influencing the distribution of benthic macroinvertebrate in 26 stream-type waterways established at upper reaches of Geum River. During study period, total 85 families, 160 species, 9305 individuals of benthic macroinvertebrates were recorded. The stream-type waterways, where the bottom substrates consist mainly of pebble (16~64 mm) and cobble (64~256 mm) or with rapid water velocity (more than 0.2 m/s) and high dissolved oxygen (more than 120%), were supported by high species diversity of benthic macroinvertebrate. Hierological cluster analysis and the nonparametric multidimensional scale (NMDS) divided 26 stream-type waterways into a total of three clusters. In Cluster 1, the invertebrate species, such as Branchiura sowerbyi, Cloeon dipterum, Ischnura asiatica, Paracercion calamorum, and Radix auricularia, closely related to aquatic macrophytes, and Chironomidae spp., Limnodrilus gotoi, and Tanypodinae sp. were abundant in waterways, with high coverage of silt and clay as well as high turbidity and total nitrogen. The benthic macroinvertebrate species (Cheumatopsyche brevilineata, Drunella ishiyamana, Dugesia japonica, Ephemera orientalis, Gumaga KUa, Macrostemum radiatum, Potamanthus formosus, Semisulcospira libertine, Stenelmis vulgaris, and Teloganopsis punctisetae) included in Cluster 2 were dominated in sites with high cover rates of pebble and gravel. Cluster 3 was predominantly covered by the Cobbles, was supported by Simulium sp. Such a clear distinction in the study sites means that each stream-type waterways is governed by a clear habitat environment. In the case of some sites with low species diversity, improvement measures are required to restore nature, such as improving the function of inflows and outflows, creating meandering channel, and inducing the settlement of littoral vegetation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.853-865
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• 2022

In this study, from August to October 2019, we conducted a survey of the spatial distribution and dominant species of macrobenthos on the rocky intertidal zones of 38 specified islands distributed along the southern coast of Korea. On the basis of observation made using 50 × 50 cm quadrats, we identified a total of 80 species, among which, Mollusca were the most abundant fauna, with 54 species that accounted for 67.4% of the total, followed by Crustacea with 15 species (18.7%). The recorded numbers of Cnidaria, Porifera, and Echinodermata species ranged from 1 to 6. In terms of the regional patterns of species richness, specified islands in Yeosu were found to be the most species rich, supporting 61 species, whereas islands in Hadong, Namhae, and Chujado were found to have a similar level of species richness, ranging from 42 to 46 species. Islands in Boseong and Goheung were home to the fewest species, with only 29 species being recorded. At the sampling station scale, we noted a considerable difference in faunal richness, ranging from 6 (St. 6) to 33 (St. 20) species. Among the recorded species, Echinolittorina radiata was identified as the dominant species on 15 specified islands, with the next most abundant species being Tetraclita japonica, considered an indicator species of climate change, which was recorded on 11 islands. In terms of frequency, E. radiata, found on 36 islands, was identified as the most frequently occurring species, followed by Reishia clavigera (30 islands), Mytilisepta virgata (29), Nerita japonica (28), Ligia. exotica (27), and Littorina brevicula (26). Of the 80 species identified, 9, 4, and 2 species of Mollusca, Crustacea, and Cnidaria, respectively, are classified as Marine fauna of accepted foreign export, whereas 50 are Red List species, 44 are species of Least Concern, 3 are Data Deficient species, and 1 species was not evaluated. However, during the survey, we found no Near Threatened or Not Applicable species. On the basis of the findings of this survey, it would appear that the abundance and richness of macrobenthic fauna inhabiting the rocky intertidal zones of specified islands along the southern coast of Korea differ according to different habitat conditions, particularly with respect to the duration of exposure and the extent and properties of the substrata. The findings of this study will provide baseline data for future monitoring and management of specified islands in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.4
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• pp.222-233
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• 2022

The heading responses of rice varieties that originated from South Korea, North Korea, and northern China were examined under the temperature and day-length conditions of 13 major rice production areas in North Korea. Kenjiandao3 and Nongdae3 originated from China, Olbyeo1, Olbyeo2 and Sonbong9 from North Korea, and Joun from South Korea demonstrated the earliest heading stage depending on the regional environment. Out of 40 rice varieties, 34 reached the heading stage within the regional safe marginal heading date (SMHD) under Haeju and Sariwon environmental conditions, while 16 to 17 varieties reached the heading stage under Wonsan, Changjon, Supung, and Yongyon environmental conditions. Some middle and mid-late maturing varieties that originated from South Korea reached the heading stage within the SMHD under the temperature and day-length conditions of Kaesong, Haeju, Sariwon, Nampo, and Pyongyang that are located in the west-southern plain. The majority of early maturing varieties, but not the middle or mid-late ones, reached the heading stage within the SMHD under the environmental conditions of Singye, Anju, Kusong, and Sinuiju. Only a few early maturing varieties demonstrated the heading stage within the SMHD under Yongyon, Changjon, and Wonsan environments. The number of days to heading was highly positively correlated among all regions; however, it was not consistent among the rice varieties. The 40 rice varieties that had been tested were classified into seven groups according to their heading responses to the temperature and day-length variations of the 13 regional conditions at 65% similarity level in cluster analysis.

• Korean Journal of School Psychology
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• v.16 no.3
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• pp.433-451
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• 2019

This study aimed to develop and validate the Classroom Problem Behavior Scale - Elementary School Version (CPBS-E) measure which is unique to classroom problem behavior exhibited by Korean elementary school students. The focus was on developing a universal screening instrument designed to identify and provide intervention to students who are at-risk for severe social-emotional and behavioral problems. Items were initially drawn from the literature, interviews with elementary school teachers, common office discipline referral measures used in U.S. elementary schools, penalty point systems used in Korean schools, 'Green Mileage', and the Inventory of Emotional and Behavioral Traits. The content validity of the initially developed items was assessed by six classroom and subject teachers, which resulted in the development of a preliminary scale consisting of 63 two-dimensional items (i.e., Within Classroom Problem Behavior and Outside of Classroom Problem Behavior), each of which consisted of 3 to 4 factors. The Within Classroom Problem Behavior dimension consisted of 4 subscales (not being prepared for class, class disruption, aggression, and withdrawn) and the Outside of Classroom Problem Behavior dimension consisted of 3 subscales (rule-violation, aggression, and withdrawn). The CPBS-E was pilot tested on a sample of 154 elementary school students, which resulted in reducing the scale to 23 items. Following the scale revision, the CPBS-E was validated on a sample population of 209 elementary school students. The validation results indicated that the two-dimensional CPBS-E scale of classroom problem behavior was a reliable and valid measure. The test-retest reliability was stable at above .80 in most of the subscales. The CPBS-E measure demonstrated high internal consistency of .76-.94. In examining the criterion validity, the scale's correlation with the Teacher Observation of Classroom Adaptation-Checklist (TOCA-C) was high and the aggression and withdrawn subscales of the CPBS-E demonstrated high correlations with externalization and internalization, respectively, of the Child Behavior Checklist - Teacher Report Form CBCL-TRF). In addition, the factor structure of the CPBS-E scale was examined using the structural equation model and found to be acceptable. The results are discussed in relation to implications, contributions to the field, and limitations.