• Safety and Health at Work
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• v.5 no.4
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• pp.222-226
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• 2014

Background: Focusing on the respiratory function for health effect indices, we conducted a cross-sectional study on workers who did and did not handle toner to compare the longitudinal changes. Methods: Among 116 individuals who worked for a Japanese business equipment manufacturer and participated in the study, the analysis included 69 male workers who we were able to follow up for 4 years. We categorized the 40 workers engaged in toner-handling work as the exposed group and the 29 workers not engaged in these tasks as the referent group, and compared their respiratory function test results: peak expiratory flow rate (PEFR), vital capacity (VC), predicted vital capacity (%VC), forced expiratory volume in 1 second ($FEV_1$), and forced expiratory volume in 1 second as a percent of forced vital capacity ($FEV_1%$). Results: The cross-sectional study of the respiratory function test results at the baseline and at the $5^{th}$ year showed no statistically significant differences in PEFR, VC, %VC, $FEV_1$, and $FEV_1%$ between the exposed and referent workers. Also, respiratory function time-course for 4 years was calculated and compared between the groups. No statistically significant differences were shown. Conclusion: Our study does not suggest any toner exposure effects on respiratory function. However, the number of subjects was small in our study; studies of larger populations will be desired in the future.

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.1-10
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• 2012

The Jinwi stream, which is located in the Gyeonggi Province, shows a large variation in water quality from the upper stream to downstream. Therefore the Jinwi stream is suitable for assessing changes to the benthic macroinvertebrate community structure according to saprobity. This study was conducted to find out the applicability of biotic indices for water quality pollution through an analysis of the correlation between water quality and benthic macroinvertebrate indices for the Jinwi stream. Along with the pollution of water, the species composition of Ephemeroptera decreased, while that of Annelida increased. The ecological score for the benthic macroinvertebrate community (ESB) showed more significant correlations than any other biotic index (H', DI, R1, J, EPT and KSI) with the water quality items.

• Journal of Korean Society on Water Environment
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• v.22 no.5
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• pp.784-795
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• 2006

The purpose of this study was to assess biological river water quality by using epilithic diatoms at 40 selected sites in Geum, Youngsan, and Seomjin River systems. The sampling and analyses were performed during three seasons including January, April and June in 2005. Various water quality parameters also were analyzed. We attempted to classify the water quality condition by epilithic diatom indices (DAIpo and TDI) with the results of corresponding analyses of various chemical water quality parameters. A five class system was delivered to describe the water quality condition ranged from "very good" to "very poor." We also proposed a way of classifying water quality condition by combining two diatom indices of DAIpo and TDI. Our results showed that biomass of epilithic diatoms varied not only seasonally but spatially; it was not likely that winter diatoms represent average water quality condition, due to high concentration of nutrients. Water quality status assessed by diatom indices was generally worse than that assessed by BOD, indicating that BOD standard likely underestimates the biological condition of the water body. Importantly, nutrient-based diatom index (TDI) generally overestimated organic matter-based index (DAIpo) at most study sites, indicating that diatoms in studied rivers were likely more affected by nutrients than organic matter. Thus, management strategy to improve river water quality in Korea is suggested to emphasize more on the nutrients than organic matters.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.43-49
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• 2016

Fishways are constructed to provide longitudinal connectivity of streams or rivers where their flow has been altered by in-stream structures such as dams or weirs. Nature-like fishways have an additional function of providing fish habitats. In the study, we estimated the role of a nature-like fishway (length: 700 m, slope: 1/100) for fish habitat by using two dominant species in the Sangju Weir, Nakdong River, to calculate the optimal ecological flow rate using Physical HABitat SIMulation (PHABSIM). To identify the dominant species that used the fishway, we conducted trap monitoring from August to November 2012 at the fishway exit. The dominant species were Zacco platypus and Opsariichthys uncirostric amurensis with a relative abundance of 62.1% and 35.9%, respectively. Optimal habitat suitability indices (HSIs) for Z. platypus and O. u. amurensis were calculated as 0.6-0.8 m/s (water velocity) and 0.2-0.4 m (water depth), and 0.5-0.7 m/s (water velocity) and 0.1-0.3 m (water depth), respectively. The optimal ecological flow rates (OEFs) for Z. platypus and O. u. amurensis were 1.6 and 1.7 cubic meter per second (CMS), respectively. The results of the study can be used in a management plan to increase the habitat function of nature-like fishways in the Sangju Weir. This methodology can be utilized as an appropriate tool that can determine the habitat function of all nature-like fishways.

• Journal of Forest and Environmental Science
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• v.32 no.1
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• pp.74-81
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• 2016

Classified into sub-tree of the growth-form, Acer pseudosieboldianum and Carpinus cordata hardly reach the uppermost canopy with limited height growth potentiality in the natural deciduous forest. However, the two species usually dominate lower stories of the forest, playing an important role in overall ecological characteristics in the forest. Based on the vegetation data of 106 $20m{\times}20m$ sample plots in Mt. Jumbong area, this study was carried out to evaluate ecological constitution by several quantitative analysis so as to understand the mechanism of the natural deciduous forest. The results indicated that individuals of A. pseudosieboldianum and C. cordata were absent or few in overstory, but emerged the most dominant species in midstory and understory, providing adequate proof of the ecological importance. The comparison of indices of succession between presented and predicted values in midstory did not make much difference, suggesting that the species composition would not change much and come close to steady state in midstory and understory. The pair combination of species association noted that A. pseudosieboldianum had significant positive association with C. cordata, Quercus mongolica, and Tilia amurensis had significant positive association with A. pseudosieboldianum, A. pictum subsp. mono and Fraxinus mandshurica but negative association with F. rhynchophylla. Being compared with other major canopy tree species in the study forest, the target species of A. pseudosieboldianum and C. cordata had strong regeneration strategies, partially characterized by large number of saplings and pole sized trees and high ratio of live crown, which indicated high shade tolerance to survive in the limited amount of light under the canopy. Even though A. pseudosieboldianum and C. cordata do not reach and occupy the canopy layer mainly due to the inherent growth form, they would have highest competitive potentiality to prosper and dominate in the midstory of the natural deciduous forest.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.1
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• pp.62-69
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• 2008

This study was conducted in order to recommend forest-based wildlife protection areas in Chung-nam Province using several basic habitat conditions. The conditions used in this study were the forest patch size with the potential to keep wildlife animals safe, the distance from water sources, and the availability of food for wildlife. The fractal dimension index was also used to find the edge line dynamics, which can influence on habitat conditions for edge species. The natural conservation management indices including a forest map (indicating the level of forest age), a slope map, and an elevation map were used to find the forest patches with enough space for wildlife to live on. Water resources and their buffer areas were considered as factors to protect the space as an ecological corridor. Deciduous trees and trees mixed with deciduous trees and conifers were chosen to provide wildlife animals their food. In total, 525 forest patches were chosen and recommended for the wildlife protection area. Five of these forest patches were recommended as wildlife protection areas managed by the provincial government. The other 520 forest patches were recommended to protect local wildlife animals and be managed by each county or city. These forest patches were located around the Geum-buk and Geum-nam mountains, and the forest patches are important resources as habitats to keep wildlife in the area. An ecological network consists of these separate forest patches with the ecological integration. A fractal dimension index was used to divide forest patches into several categories in order to find how patches are shaped. The forest patches with longer edges or more irregular shapes have a much higher possibility of being inhabited by various types of edge species. Through comparison of the wildlife protection areas recommended in this study to the current wildlife protection areas, we recognized that the current wildlife protection areas need boundary adjustments in order for wildlife animals to survive by themselves with water sources and food.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.6
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• pp.1007-1016
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• 2021

This study examined the characteristics and seasonal distribution patterns of subtidal marine algal communities along the east coast of Korea, from 2016 to 2017, and recorded the coverage ratio (%) by the algal type. During the study period, 134 marine algae species (16 green, 29 brown, and 89 red) were identified at the survey sites. The maximum number of species was observed at the Nagok site (70 species), and the minimum at the Gisamoon site (50 species). The total average biomass (dry weight) during the survey period was 66.22 g/m², including green algae (2.19 g/m²), brown algae (38.10 g/m²), and red algae (25.94 g/m²). The dominant seaweeds in the vertical distribution based on coverage rates (%) were Sargassum yezoense and Dictyopteris divaricata at the upper, Symphyocladia latiuscula and Undaria pinnatifida at the middle, and Agarum clathratum subsp. yakishiriense and Plocamium telfairiae at the lower sections of the distribution. Richness, evenness, and diversity index, calculated based on the biomass of the abundant species, were estimated to be 6.36, 0.55, and 1.98, respectively, over the entire sea area. Based on the evaluation of the environmental states using community indices, the ecological evaluation index (EEI-c) of subtidal marine algal communities along the east coast of Korea was marked as 'good-moderate'.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.4
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• pp.55-64
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• 2022

The objectives of this study were to assess physical habitat suitability of fish species for different life cycle stages and to suggest appropriate ecological stream flows in a Bokha downstream reach. A dominant species of Zacco platypus was selected as the study fish of which three stages of spawning, juvenile and adult in life cycle were considered into assessment. The stream hydraulic environment was calibrated with HEC-RAS before the PHABSIM simulation. The hydraulics of flow velocity and depth were used to estimate Weighted Usable Area (WUA) by multiplying respective habitat suitability indices with stream area. Overall the WUAs tend to be great in gentle slopes with relatively shallow water depth regions. Maximum WUAs, ie, candidate for ecological flow rates were 1 m³/s, 7 m³/s and 8 m³/s for the respective spawning, juvenile and adult stages of Zacco platypus. Since the ecological flow rates for juvenile and adult stages appeared to be is greater than the abundant flow rate (3.67 m³/s) for the study reach, additional water supply may be needed but should be cautious to avoid the spawning period of Apr through May from the stream water management perspective.

• The Korean Journal of Ecology
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• v.27 no.2
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• pp.99-106
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• 2004

We developed the estimation model for the vegetation developmental processes on the severely burned slope areas after forest fire in the east coastal region, Korea. And we calculated the vegetation indices as a useful parameter for the development of land management technique in the burned area and suggested the changes of the vegetation indices after forest fire. In order to estimate the woody standing biomass in the burned area, allometric equations of the 17 woody species regenerated by sprouter were investigated. According to the our results, twenty year after forest fire need for the development to the normal forest formed by 4 stratum structure, tree, sub-tree, shrub and herb layer. The height of top vegetation layer, basal area and standing biomass of woody species show a tendency to increase linearly, and the ground vegetation coverage and litter layer show a tendency to increase logarithmically after forest fire. Among vegetation indices, Ive and Ivcd show a tendency to increase logarithmically, and Hcl and Hcdl show a tendency to increase linearly after forest fire. The spatial variation of the most vegetation factors was observed in the developmental stages less than the first 5 years which were estimated secondary disaster by soil erosion after forest fire. Among vegetation indices, Ivc and Ivcd were the good indices for the representation of the spatial heterogeneity in the earlier developmental stages, and Hcl and Hcdl were the useful indices for the long-term estimation of the vegetation development after forest fire.

• The Korean Journal of Ecology
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• v.16 no.2
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• pp.209-227
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• 1993

Aquatic insects were collected from 18 sites in the Yongsan River System from August, 1988 to July, 1989. The monthly fluctuation and distributional pattern of the aquatic insects along the environmental factors were investigated. Quantitatively collected aquatic insects were identified, and numbers, standing biomass, dominance indices and diversity indices in each site and month were determined. The aquatic insect faun of the Yongsan River System was composed of 146 species, 82 genera, 38 families in 7 orders including 44 species of mayflies, 32 species of caddisflies, 24 species of stoneflies, 21 species of flies, 16 species of beetles, 6 species of dragonflies and 3 species of dobsonflies. Seasonal occurrence of species were more diversified in winter and spring than in summer. Also, the number of individuals occurred was higher in winter and spring than in summer while it was the highest in upper stream and the lowest in Kwang-ju stream. Component ratio of the number of individuals according to the insect orders was as follows: Mayflies 38.71%, Flies 36.97%, Stoneflies 10.21%, Caddisflies 6.80%, Beetles 2.96%, Dobbsonflies 2.74%, Dragonflies 0.95%. Percentage of standing biomass according to insect orders were as follows: Mayfiles 32.81%, Stoneflies 26.51%, Caddisflies 17.58%, Dobbsonflies 14.84%, Flies 3.74%, Beetles 3.08%, Dragonflies 1.45%, The highest standing biomass occurred in spring and the lowest in summer.