• Journal of Wetlands Research
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• v.18 no.1
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• pp.32-38
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• 2016

The purpose of this study is to investigate the effects of the natural river conservation work and to find remedies for them, targeting Jangsu-cheon with high frequency of use by citizens among the rivers in Incheon Metroplitan City, Korea; for this, this study conducted investigations and analyses of Jangsu-cheon completed in December, 2008. As a result of investigating 3 spots for the water system of Jangsu-cheon over a total of 3 years (2009, 2010, 2014), it was found that benthic macro-invertebrates of a total of 3 phyla, 5 classes, 11 orders, 26 families, 56 species, and 980 specimens were distributed there. When they were analyzed by year, 18 families and 30 species in 2009, right after the natural river conservation work, and 22 families and 37 species in 2010, 2 years after the work, were found, with 7 species increasing in number; after that, as a result of the investigation in 2014, 22 families and 38 species were found, which tells the river has entered the stabilization stage since the recovery in 2010.Therefore, this study could identify: the water environment of the river was improved due to the natural river conservation work for Jangsu-cheon; in addition, Jangsu-cheon showed good ecological environment due to the continuous maintenance of the good wetlands in Incheon Grand Park in the upper area of the river; and the natural river conservation work of Jangsu-cheon created positive effects.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.340-347
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• 2001

Seasonal variation of the elemental and biochemical composition of the suspended particulate matter (SPM) was investigated in terms of quantity and quality of diets for suspension feeders from July 1999 to August 2000 in two coastal bay systems of Gosung and Kangjin Bays in Korea. No clear patterns in the seasonal variations of SPM concentration were found in these two bay systems. The results indicated that the seasonal variation of SPM could not be considered the variation of food available to suspension-feeders. The simultaneous peaks in chlorophyll a and biochemical components in summer indicated that the quantity of the particulate organic matter primarily depended on phytoplankton productivity. However, no correlation between chlorophyll a and biochemical components [particulate protein (PPr), carbohydrate (PCHO) and lipid] were found, indicating that other processes might also contribute to the particulate organic matter in the period when the phytoplankton biomass was low. High C: Chl a and C:N, and carbohydrate peaks during the autumn to spring period suggested that resuspension of surface sediments was a probable process to supply the particulate organic matter. The food material, represented by summing up the total quantity of three biochemical components, was highest in spring with minor peaks during the period from autumn to the next spring, The food index, calculated as the ratio of food material to total SPM, did not generally exceed $6\%$ with short peaks during the year. Therefore, nutritional quality of SPM in the bays are relatively poor than in other more productive coastal waters in the world. Our results confirm that the measurement of a single chemical variable cannot describe fully the nutritive value of the seston available to suspension-feeders as previously proposed, and the biochemical composition of SPM can provide effective information on its origin and nutritive Quality.

• The Korean Journal of Ecology
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• v.24 no.1
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• pp.1-7
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• 2001

This study was carried out to examine the recovery of forest ecosystem by changes of soil chemical properties and soil microorganism at the burned areas of coniferous (Mt. Chocdae) and broad leaved forest (Samsinbong in Mt. Chiri). In the soil chemical properties of the burned area of Samsinbong, pH was 5.8, and contents of organic matter, total nitrogen, available P₂O/sub 5/, exchangeable K/sup ＋/, exchangeable Ca/sup ＋＋/ and exchangeable Mg/sup ＋＋/ were 7.42%, 0.73%, 28.5 ㎎/㎏, 1.3 me/100g, 13.3 me/100g and 2.2 me/100g, respectively. But they showed a tendency to decrease with time. In the soil chemical properties of the burned area of Mt. Chocdae, pH was 5.3, and contents of organic matter, total nitrogen, available P2O5, exchangeable K/sup ＋/, exchangeabe Ca/sup ＋＋/ and Exchangeable Mg/sup ＋＋/ were 6.42%, 0.25%, 24.4 ㎎/㎏, 0.7 me/100g, 3.7 me/100g and 2.1 me/100g, respectively, and they also showed a tendency to decrease with time. In contrast, they were not changed with time at the unburned areas. At the burned area of Samsinbong, soil microorganism showed to order of fungi (69×10⁴ CFU), actinomycetes (523×10⁴ CFU) and aerobic bacteria (291×10⁴ CFU), and at the unburned area, showed to order of actinomycetes (745×10⁴ CFU), fungi (594×10⁴ CFUU), and aerobic bacteria (160×10/sup 4/ CFU). At the burned area of Mt. Chocdae, soil microorganism showed to order of fungi (676×10⁴ CFU), actinomycetes (434×10⁴ CFU) and aerobic bacteria (350×10⁴ CFU), and at the unburned area, showed to order of fungi (461 ×10⁴ CFU), aerobic bacteria (328×10⁴ CFU) and actinomycetes (319×10⁴ CFU). Soil microorganisms of the aerobic bacteria, actinomycetes and fungi appeared at the burned areas were much more abundant than unburned areas. The aerobic bacteria appeared at the coniferous forest were also much more than the broad-leaved forest. The actinomycetes and fungi appeared at the broad-leaved forest were much more abundant than the coniferous forest.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.6
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• pp.98-109
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• 2011

Habitat restoration initiative is an important factor for the on-site preservation of butterflies. A new habitat necessitates the investigation of the ecology of the butterfly, the landscape of the habitat, the work process, and a cost analysis. In this study, these factors were analyzed through1) re-consideration of the secured results from three years of field work, and 2) a habitat area estimation conducted according to the presence or absence of larvae and adults via a Parnassius bremeri Bremer survey. The investigation of the natural habitat, done for both larvae and adult butterflies found in South Korea, suggested that multiple patches with a minimum size exceeding $300m^2$ and with an average size of about $1,600m^2$were required for survival of this butterfly. Therefore, more than five patches should be considered for butterfly habitat and patches should have similarity to the present habitat environment with transplantation plans for diet plants and honeydew plants. In addition, to activate the migration of the butterfly, cutting down trees that are obstacles to migration, minimizing the distance between patches and the addition of a stepping patch are also required. A patch connectivity analysis showed that patches should be located within 300m of neighboring patches, as the migration of the butterfly will fail if it is more than 600m. Additionally, more than $10,000m^2$ for a single patch or a patch network composed more than five patches over $1,600m^2$ in size were recommended, with a total patch size of $8,000m^2$. Additionally, neighboring multiple patch networks are more desirable than a single habitat in the event a cyclic habitat pattern arises. In this study, we suggest a habitat restoration and optimal prerequisites for a butterfly habitat. It is expected that this research will lead to the creation of a good model for the restoration of butterfly species.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.4
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• pp.23-34
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• 2017

This study focused on a planned site located in Gosangol Village in Daegu Metropolitan City that aims to build an urban agricultural park combining urban agriculture and urban park for the sustainable realization of urban agriculture. Accordingly, this study has significance in two perspectives: firstly, suggesting development strategies to be considered when building an urban agricultural park as a theme park, and secondly, presenting guidelines for spatial programs and facilities to be introduced for actual applications. The results are as follows. Firstly, building an urban agricultural park fills a role as a local community space prompted by the demand-oriented evolution of urban parks, and agricultural behaviors to be incorporated in the theme. In this context, 'building an urban agricultural space focusing on sustainability', 'constructing green space systems focusing on agricultural landscape', and 'structuring leisure spaces for communications in the community' are presented as development strategies. Secondly, key functions that an urban agricultural park should have include production and trade of agricultural products on the production side, soil preservation, resource cycling and green space provision on the environmental side, leisure and experience, community vitalization, education, and social security on the social and cultural side, and entertainment functions, ecological functions, and protective functions as urban park functionality. Thirdly, key facilities needed when building an urban agricultural park include urban agricultural facilities other than park management facilities, landscape facilities, recreational facilities, sports facilities, educational facilities, and convenient facilities, and family gardens as the key facility of the urban agricultural park should be scaled in consideration of various purposes and behaviors of their use. This study has a limitation that the subject site was limited to a specific area but has significance in that it presented a planning model for the spatial structuring of park-type urban agriculture.

• Korean journal of applied entomology
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• v.53 no.2
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• pp.193-197
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• 2014

Transgenic crops that produce insecticidal toxins have a great potential for controlling target pest insects, but there is a growing concern about unintended influences on non-target species. In the present study, the preferences and performance of non-target green peach aphid, Myzus persicae (Sulzer), on transgenic cabbages (Brassica oleracea) that produce Bt toxin (Cry1Ac1) and untransformed control plants were investigated as a part of risk assessment. In a free-choice situation, the number of nymphs larviposited by 10 winged adults over 3 days was $21.9{\pm}1.8$ and $22.5{\pm}2.2$ on transgenic and the control plants, respectively, indicating that the aphids did not discriminate between the two types of plants. In a performance assay, the development time (D) and intrinsic rate of increase (rm) of wingless aphids reared on transgenic and control plants were also similar (D, $5.8{\pm}0.2$ and $5.9{\pm}0.1$ (days) and rm, $0.7{\pm}0.1$ and $0.8{\pm}0.1$, for transgenic and control plants, respectively). These results suggest that M. persicae is not significantly affected by transgenic Bt cabbage.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.3
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• pp.151-157
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• 2015

Recent laboratory studies have documented that mixotrophic dinoflagellates Dinophysis spp. and heterotrophic dinoflagellate Oxyphysis oxytoxoides share a common prey, i.e. the mixotrophic ciliate Mesodinium rubrum. Nonetheless, very little is known about the population dynamics and species interactions among these protists in natural environments. To investigate the interactions between the dinoflagellate predators and their ciliate prey in the field, we took the samples twice a day from 26 July to 28 August, 2011 at a fixed station in Masan Bay and analyzed their abundances. During this study, salinity was highly variable, ranging from 5 to 28, due to the periodic input of rainfalls to the sampling station. Water temperature was on average $26.5^{\circ}C$ until 20 August and thereafter was about $21^{\circ}C$ by the end of the sampling period. The ciliate M. rubrum occurred persistently throughout the sampling period, ranging from 13 to $492\;cells\;mL^{-1}$. Cell densities of D. acuminata and O. oxytoxoides ranged from undetectable level to $19,833\;cells\;L^{-1}$ and from undetectable level to $100,333\;cells\;L^{-1}$, respectively. The high abundance of D. acuminata mostly followed the blooming of the ciliate M. rubrum, but it often did not peak even during heavy blooms of the prey, probably due to sensitivity to large salinity fluctuation and also presumably overlapped grazing by other mixotrophic dinoflagellates. The abundance of O. oxytoxoides was detected only when water temperature was lower than $24^{\circ}C$, indicating that water temperature is an important environmental factor to control the population dynamics of the dinoflagellate species.

• Korean Journal of Ecology and Environment
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• v.38 no.3 s.113
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• pp.322-333
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• 2005

Total phosphorus (TP) and suspended solids (SS) were measured in the discharge waters from 5 drainage basins of Lake Yongdam, from April, 2002 till March, 2004. The responses of SS and TP to rainfall were analyzed and their loadings into Lake Yongdam were calculated. The inflowing rivers into Lake Yongdam were the Juja River, the Jeongja River, the Jinan River, the Geum River and the Guryang River. Among these rivers Jinan River showed the highest TP that fluctuated very much according to the flow rate. TP and the flow rates (Q) of each river showed positive correlations with empirical relationsip of $TP\;=\;6.32Q^{0.30}$ for the Juia River, $TP\;=\;8.58Q^{0.49}$ for the Jeongia River, $TP\;=\;307.92Q^{0.10}$, for the Jinan River, $TP\;=\;17.91Q^{0.47}$, for the Geum River, $TP\;=\;20.11Q^{0.53}$ for Guryang River. In April 2002 ${\sim}$ March 2003, phosphorus loadings from the Juja River, the Jeongja River, the Jinan River, the Geum River and the Guryang River were calculated to be 3,677, 11,430, 36,412, 89,651, and 42,226 kgP ${\cdot}$ $yr^{-1}$ respectively. And the specific loadings from the Juja River, the Jeongia River, the Jinan River, the Geum River and the Guryang River were calculated to be 0.3, 2.9, 13.6, 9.3, and 13.0 kgP ${\cdot}$ $km^{-2}$ ${\cdot}$ $yr^{-1}$ respectively. In April 2002 ${\sim}$ March 2004, the suspended particles loading from the Juja River, the Jeongia River, the Jinan River, the Geum River and the Guryang River were 673, 1,232, 4,232, 30,902, 80,202 ton ${\cdot}$ $yr^{-1}$ respectively. The Guryang River showed the largest contribution of SS loading.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.336-343
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• 2003

Two types of statistical models, simple and multivariate log linear models, were studied for continuity simulation and trend analysis of water qualities in incoming flows to Lake Paldang. Water quality is a function of one independent variable (flow) in the simple log linear model, and of three different variables (flow, time, and seasonal cycle) in multivariate model. The independent variables act as surrogate variables of water quality in both models. The model coefficients were determined by the monthly data. The water qualities included 5-day Biochemical Oxygen Demand ($BOD_5$), Total Nitrogen (TN), and Total Phosphorus (TP) measured from 1995 to 2000 in the South and the North branches of Han River and the Kyoungan Stream. The results indicated that the multivariate model provided better agreements with field measurements than the simple one in a31 attempted cases. Flow dependency, seasonality, and temporal trends of water quality were tested on the determined coefficients of the multivariate model. The test of flow dependency indicated that BOD concentrations decreased as the water flow increased. In TN and TP concentrations, however, there were no discernible flow effects. From the temporal trend analyses, the following results were obtained: 1) no trends on BOD at all three upstreams, 2) increase on TN at the South Branch and the Kyoungan Stream, 3)decrease on TN at the North Branch,4) no trends on TP at the North and the South Branches and 5) increase on TP at the Kyoungan Stream by 3 to 8% per years. The seasonality test showed that there were significant seasonal variations in all three water qualities at three incoming flows.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.235-241
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• 2003

The effect of ultraviolet (UV) radiation on the characteristics of algae-derived dissolved organic matter (DOM) was examined by comparing the biodegradability and DOM fraction distribution of algal DOM before and after UV exposure. Algal DOM from two axenic cultures of Microcystis aeruginosa and Oscillatoria agardhii were irradiated for 24 h at a UV intensity of 42 W/$m^2$. A complete degradation of algal DOM during the UV exposure did not occur, remaining at constant concentrations of dissolved organic carbon(DOC). After UV exposure, however, microbial degradations were reduced by 17% in M. aeruginosa and 53% in O. agardhii, respectively, and decomposition rates also were two times lower in UV exposed algal DOM. In addition, the chemical compositions of algal DOM altered substantially after UV radiation exposure. The proportions of hydrophilic bases (HiB; protein-like DOM) decreased considerably in both algal DOM sources after UV exposure (16.8% and 20.0% of DOM, respectively), whereas those of hydrophilic acids (HiA; carboxylic acids-like DOM) increased as much as the decrease of the HiB fraction. Capillary ion electrophoresis (CE) analysis showed that several carboxylic acids increased significantly after UV exposure, further confirming an increase in HiA fractions. The results of this study clearly indicate that algal DOM can be changed in its chemical composition as well as biodegradability without complete degradation by UV radiation.