• Journal of Korea Water Resources Association
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• v.50 no.12
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• pp.837-847
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• 2017

Land Surface Model (LSM) was developed for the Soyang river basin located in Korean Peninsula to clarify the spatio-temporal variability of hydrological weather parameters. Variable Infiltration Capacity (VIC) model was used as a LSM. The spatial resolution of the model was 10 km and the time resolution was 1 day. Based on the daily flow data from 2007 to 2010, the 7 parameters of the model were calibrated using the Isolated Particle Swarm Optimization algorithm and the model was verified using the daily flow data from 2011 to 2014. The model showed a Nash-Sutcliffe Coefficient of 0.90 and a correlation coefficient of 0.95 for both calibration and validation periods. The hydrometeorological variables estimated for the Soyang river basin reflected well the seasonal characteristics of summer rainfall concentration, the change of short and shortwave radiation due to temperature change, the change of surface temperature, the evaporation and vegetation increase in the cover layer, and the corresponding change in total evapotranspiration. The model soil moisture data was compared with in-situ soil moisture data. The slope of the trend line relating the two data was 1.087 and correlation coefficient was 0.723 for the Spring, Summer and Fall season. The result of this study suggests that the LSM can be used as a powerful tool in developing precise and efficient water resources plans by providing accurate understanding on the spatio-temporal variation of hydrometeorological variables.

• Journal of Korean Society of Forest Science
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• v.88 no.1
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• pp.38-46
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• 1999

Canopy structure conductances of a Norway spruce forest in the Solling Hills(Central Germany) and Central Forest Biosphere Reserve(320km to the north-west from Moscow) were derived from LE(latent heat flux) and H(sensible heat flux) fluxes measured(by Eddy correlation technique and energy balance method) and modelled(by one dimensional non-steady-state) SVAT(soil-vegetation-atmosphere-transfer) model(SLODSVAT) using a rearranged Penman-Monteith equation("Big-leaf" approximation) during June 1996. They were compared with canopy stomatal conductances estimated by consecutive intergrating the stomatal conductance of individual needles over the whole canopy("bottom-up" approach) using SLODSVAT model. The result indicate a significant difference between the canopy surface conductances derived from measured and modelled fluxes("top-down" approach) and the stomatal conductances modelled by the SLODSVAT("bottom-up" approach). This difference was influenced by some nonphysiological factors within the forest canopy(e.g. aerodynamic and boundary layer resistances, radiation budget, evapotranspiration from the forest understorey). In general, canopy surface conductances derived from measured and modelled fluxes exceeded canopy stomatal conductance during the whole modelled period, The contribution of the understorey's evapotranspiration to the total forest evapotranspiration was small (up to 5-9% of the total LE flux) and was not depended on total radiation balance of forest canopy. Ignoring contribution of the understorey's evapotranspiration resulted in an overestimation of the canopy surface conductance for a spruce forest up to 2mm/s(about 10-15%).

• Korean Journal of Plant Taxonomy
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• v.38 no.4
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• pp.583-599
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• 2008

Dokdo, small island located in the eastern end of the Korean Peninsula, has been an uninhabited island for long time due to long distance from the land. Moreover, the steep slope of volcanic tuff at Dokdo is well drained for high permeability and Dokdo has few plain areas, swamps and very thin soil layers. In this study, pollen analysis at Dokdo was attempted on the profile of organic sandy soil for the first time in Korea owing to the marine climate environment with high humidity and precipitation including snowfalls in spite of unprofitable condition geologically or geomorphologically. While many historical, political researches have been accumulated for territorial problem of Dokdo with Japan, natural scientific researches with field work are not sufficient, and few paleoecological researches have been done. As a result of pollen analysis, the ratio of the NAP(Non-Arboreal Pollen) and spore was higher than AP(Arboreal Pollen), and the vegetation change existed by showing dramatic decrease of AP at the upper layer. AP was composed of almost Pinus, and a little Alnus, Quercus, Betula, Carpinus, Picea and Ulmus. NAP was composed of Gramineae, Compositae, Chenopodiaceae Cyperaceae, Caryophyllaceae, Liliaceae, Umbelliferae, Artemisia, Lobelia, Rumex, Polygonum. Increase of the NAP such as Gramineae, Artemisia and Chenopodiaceae, they would mostly have been transported from the other areas because agricultural activity is impossible at Dokdo. While one reason of Pinus thunbergii decrease could be regarded as environmental change, the other reason would be lumbering of pine trees by human activity which is adapted to Dokdo environment.

• Korean Journal of Environment and Ecology
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• v.16 no.4
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• pp.457-464
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• 2003

A valley forest in Sangbuun area at Jirisan National Park was studied to investigate forest structure in relation to altitude and part of the slope. Forty-eight quadrats were set up in the valley forest along altitude of 726m to 1,090m and part of the slope, and vegetation analysis for the woody species in the tree and subtree layers were carried out. With increasing elevation belt, mean DBH, height and basal area of the trees in the tree layer increased while their density decreased. This trends may be caused by the disturbance which was relatively severe in the low elevation area. As elevation increased, the importance percentages of Fraxinus rhynchophylla, Quercus variabilis and Quercus mongolica increased while those of Styyax japonicus, Carpinus laxiflora and Pinus densiflora decreased. The importance percentages of Quercus variabilis and Pinus densiflora increased as going from lower part to upper part of the slope. However, the opposite trend was found for the importance percentages of Acer mono and Corlus heterophylla var. thunbergii. Number of species and species diversity decreased as increasing elevation and going from lower part to upper part of the slope. According to importance percentage and cluster analysis, the valley forest was classified into three forest communities of Quercus serrata-broad-leaved tree species community in lower part of the slope at low elevation belt, middle elevation belt and middle and upper parts of the slope at high elevation belt, Pinus dnsiflora-Quercus serrata community in middle and upper parts at low elevation belt, and Quercus mongolica-broad-leaved tree species community in lower part of the slope at high elevation belt and top area.

• Korean Journal of Environment and Ecology
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• v.10 no.1
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• pp.66-75
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• 1996

To propose basic information for national resource management and planting disign, plant community structure of evergreen broad-leaved forest was investigated. Fifty-two plots(each size 300m$^{2}$) were set up at Ch'omch'alsan area of Chindo, Korea. TWINSPAN and DCA methods were used for classification and ordination analysis. Fifty-two plots were divided into seven groups, which were Quercus variabilis-Carpinus tschonoskii community, Q. glauca community, Castanepsis cuspidata var. sieboldii-Q. stenophylla community, Castanopsis cuspidata var. sieboldii-Camelia japonica community, Q. acuta-Camelia japonica community, Carpinus coreaca-Q spp. community, C. coreana community. Pinus densiflora almost have been selected. Carpinus tschomoskii, Q. variabillis and Q. serrata were to be succeeded by Castanea cuspidata var. sieboldii, Q. stenophylla, Q. acuta and Neolitsea sericea in canopy layer. And Neolitsea sericea, Q. glauca and Camellia japonica was showed high importance values in fertile soil condition. Future restoration plan was necessary for a tourist resort or national forest in warm temperate region. And evergreen broad-leaved plants shall be planted in considering of environmental condition at warm temperate and industrial complex area.

• Journal of Korean Society of Forest Science
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• v.99 no.4
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• pp.534-545
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• 2010

To examine 1) rainfall pattern (i.e., type and intensity) regulating surface erosion on hillslopes in postwildfire area and 2) its effect on variation in sediment yield along the gradient of severity wildfire regimes and elapsed years, we surveyed the amount of sediment yield with respect to daily or net-effective rainfall in 9 plots in eastern coastal region, Republic of Korea. Before field investigation, all plots classified into three groups: low-, mixed- and high-severity wildfire regimes (3 plots in each group). We found that, with decreasing wildfire regimes and increasing elapsed years, the rainfall type regulating surface erosion changed from daily rainfall to net-effective rainfall (considering rainfall continuity) and its intensity increased continuously. In general, wildfires can destroy the stabilized forest floors, and thus rainfall interception by vegetation and litter layer should be reduced. Wildfires can also decrease soil pores in forest floors, and thus infiltration rates of soil are reduced. These two processes lead to frequent occurrence of overland flows required to surface erosion, and sediment yields in post-wildfire areas should increase linearly with increasing rainfall events. With the decreasing severity wildfire regimes and the increasing elapsed years, these processes should be stabilized, and therefore their sediment yields also decreased. Our findings on variations in sediment yields caused by the wildfire regimes and the elapsed years suggest understanding of hydrogeomorphic and ecologic diversities in post-wildfire areas, and these should be carefully examined for both watershed management and disaster prevention.

• Korean Journal of Plant Taxonomy
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• v.36 no.1
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• pp.61-89
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• 2006

Algific talus slopes are local cold micro-environmental habitats where cool air escapes through vents and fissures of talus layer, and ice forms in summer. To access the phytogeographical significance and to develop the conservation strategy on vegetation of the algific talus, plant species composition on seven algific talus in South Korea was investigated. As a results, phytogeographically significant northern elements such as Cystopteris fragilis (L.) Bernh., Diplazium sibiricum (Turcz. ex Kunze) Sa.Kurata, Polypodium virginianum L., Vaccinium vitis-idaea L. and Hackelia deflexa (Wahlenb.) Opiz were distributed in these algific talus slopes (below $N37^{\circ}43^{\prime}$). In addition, subalpine species such as Woodsia subcordata Turcz, Rosa suavis willd., Clematis fusca var. coreana ($H.L{\acute{e}}v.$ & Vaniot) Nakai, Calamagrostis langsdorfii (Link) Trin. and Carex vaginata var. petersii (C.A.Mey.) Akiyama were also distributed as typical relictual species of these algific talus (less than alt. 400m). The algific talus slopes in Korean peninsular can be regarded as the insular refugia that northern plant species advanced southward during the latest glacial age have been isolated and adapted in some local microhabitats. Because the algific talus slopes as paleorefugia are very important in terms of phytogeography as well as meteorology ans geology, developments of strategies for in situ and ex situ conservation on these small isolated and threatened populations associated with the algific talus urgently needed.

• Journal of Convergence for Information Technology
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• v.10 no.12
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• pp.201-207
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• 2020

In this study, the practicality of unmanned aerial vehicle photography information was identified. Therefore, a total of four consecutive surveys were conducted on the field-level survey areas among the areas subject to photography using unmanned aerial vehicles, and the changes in crop conditions were analyzed using pictures of unmanned aerial vehicles taken during each survey. It is appropriate to collect and utilize photographic information by directly taking pictures of the survey area according to the time of the on-site survey using unmanned aerial vehicles in the field layer, which is an area where many changes in topography, crop vegetation, and crop types are expected. And it turned out that it was appropriate to utilize satellite images in consideration of economic and efficient aspects in relatively unchanged rice paddies and facilities. If the survey area is well equipped with systems for crop cultivation, deep learning can be utilized in real time by utilizing libraries after obtaining photographic data for a certain area using unmanned aircraft in the future. Through this process, it is believed that it can be used to analyze the overall crop and shipment volume by identifying the crop status and surveying the quantity per unit area.

• Ecology and Resilient Infrastructure
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• v.9 no.4
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• pp.228-236
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• 2022

Riverbank revetments are installed to increase the stability, while preventing scouring, and utilize the rivers; their construction is prioritized to secure dimensional safety that can withstand flooding. Existing revetment technologies employ use of rocks, gabions, and concrete. However, stone and gabions are easily erosion and destroyed by extensive flooding. Though the materials used in concrete technology possess strength and stability, the strong base adversely affects the aquatic ecosystem as components leach and remain in water for a long time. This serves as an environmental and ecological issue as vegetation does not grow on the concrete surface. This study introduces multi-layer porous riverbank revetment technology using biopolymer materials extracted from castor oil. Results obtained from this study suggest that this technology provides greater dimensional stability as compared to existing technologies. Moreover. it does not release toxic substances into the rivers. Multiple experiments conducted to review the application of this technology to diverse river environments confirm that stability is achieved at a flow velocity of 8.0 m/s and maximum tractive force of 67.25 kg_f/m² (659.05 N/m²).

• The Journal of Engineering Geology
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• v.33 no.1
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• pp.69-83
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• 2023

Forest fires increase the risk of subsequent soil erosion and mass movement in burned areas, even under rainfall conditions below landslide alert thresholds, by destroying plants and vegetation and causing changes to soil properties. These effects of forest fires can alter runoff in burned areas by altering soil composition, component minerals, soil water repellency, soil mass stability, and soil fabric. Heat from forest fires not only burns shallow organic matter and plants but also spreads below the surface, affecting soil constituents including minerals. This study analyzed X-ray diffraction and physical properties of topsoil and subsoil obtained from both burned and non-burned areas to identify the composition and distribution of clay minerals in the soil. Small amounts of mullite, analcite, and hematite were identified in burned soils. Vermiculite and mixed-layer illite/vermiculite (I/V) were found in topsoil samples from burned areas but not in those from non-burned areas. These findings show changes in soil mineral composition caused by forest fires. Expansive clay minerals increase the volume of soil during rainfall, degrading the structural stability of slopes. Clay minerals generated in soil in burned areas are therefore likely to affect the long-term stability of slopes in mountainous areas.