• The Plant Pathology Journal
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• v.17 no.2
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• pp.67-70
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• 2001

Medicago truncatula is a diploid legume plant related to the forage crop alfalfa. Recently, it has been chosen as a model species for genomic studies due to its small genome, self-fertility, short generation time, and high transformation efficiency. M. truncatula engages in symbiosis with nitrogen-fixing soil bacterium Rhizobium meliloti. M. truncatula mutants that are defective in nodulation and developmental processes have been generated. Some of these mutants exhibited altered phenotypes in symbiotic responses such as root hair deformation, expression of nodulin genes, and calcium spiking. Thus, the genes controlling these traits are likely to encode functions that are required for Nod-factor signal transduction pathways. To facilitate genome analysis and map-based cloning of symbiotic genes, a bacterial artificial chromosome library was constructed. An efficient polymerase chain reaction-based screening of the library was devised to fasten physical mapping of specific genomic regions. As a genomics approach, comparative mapping revealed high levels of macro- and microsynteny between M. truncatula and other legume genomes. Expressed sequence tags and microarray profiles reflecting the genetic and biochemical events associated with the development and environmental interactions of M. truncatula are assembled in the databases. Together, these genomics programs will help enrich our understanding of the legume biology.

• Korean Journal of Remote Sensing
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• v.16 no.4
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• pp.327-338
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• 2000

The forest conditions of North Korea has been a great concern since it was known to be closely related to many environmental problems of the disastrous flooding, soil erosion, and food shortage. To assess the long-term changes of forest area as well as the canopy conditions, several sources of multitemporal satellite data were applied to the study area near Kaesung. KOMPSAT-1 EOC data were overlaid with 1981 topographic map showing the boundaries of forest to assess the deforestation area. Delineation of the cleared forest was performed by both visual interpretation and unsupervised classification. For analyzing the change of forest canopy condition, multiple scenes of Landsat and SPOT data were selected. After preprocessing of the multitemporal satellite data, such as image registration and normalization, the normalized difference vegetation index (NDVI) was derived as a representation of forest canopy conditions. Although the panchromatic EOC data had radiometric limitation to classify diverse cover types, they can be effectively used t detect and delineate the deforested area. The results showed that a large portion of forest land has been cleared for the urban and agricultural uses during the last twenty years. It was also found that the canopy condition of remaining forests has not been improved for the last twenty years. It was also found that the canopy condition of remaining forests has not been improved for the last twenty years. Possible causes of the deforestation and the temporal pattern of canopy conditions are discussed.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.587-596
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• 2011

The interest in hydrological modeling has increased significantly recently due to the necessity of watershed management, specifically in regards to lumped models, which are being prosperously utilized because of their relatively uncomplicated algorithms which require less simulation time. However, lumped models require empirical coefficients for hydrological analyses, which do not take into consideration the heterogeneity of site-specific characteristics. To overcome such obstacles, a distributed model was offered as an alternative and the number of researches related to watershed management and distributed models has been steadily increasing in the recent years. Thus, in this study, the feasibility of a grid-based rainfall-runoff model was reviewed using the flood runoff process in the Han River basin, including the ChungjuDam, HoengseongDam and SoyangDam watersheds. Hydrological parameters based on GIS/RS were extracted from basic GIS data such as DEM, land cover, soil map and rainfall depth. The accuracy of the runoff analysis for the model application was evaluated using EFF, NRMSE and QER. The calculation results showed that there was a good agreement with the observed data. Besides the ungauged spatial characteristics in the SoyangDam watershed, EFF showed a good result of 0.859.

• Journal of Environmental Science International
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• v.31 no.6
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• pp.461-470
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• 2022

When an agricultural soil dam collapses, the extent of inundation and the rate of diffusion vary depending on where the collapse occurs in the dam body. In this study, a dam collapse scenario was established and a two-dimensional numerical model FLO-2D was used to closely examine the inundation pattern of the downstream residential area according to the dam collapse point. The results were presented as a flood risk map showing the changes and patterns of the extent of inundation spread. The flood level and the time to reach the maximum water level vary depending on the point of collapse, and the inundation of the downstream area proceeds rapidly in the order of the midpoint, left point, and right point collapse. In the left collapse point, the submergence appeared about 0.5 hour slower than the middle point, and the right collapse point appeared about 1 hour slower than the middle point. Since the relative damage pattern is different depending on the dam collapse point, insurance and disaster countermeasures will have to be established differently.

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.103-113
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• 1995

To estimate buffer capacity and sensitivity of forest ecosystem to acid rain in Taejon, ionic components of throughfall, stemflow, soil leachate, and open rain in Pinus rigida and Quercus variabilis forest were analysed. The spatial sensitivity based on parent rock and forest type was given by IDRISI of GIS which created imagery conversion from soil and vegetation map. Parent rocks and soils were classified into acidic, sedimentary, metamorphic rock and then subdivided based on $SiO_2$ content. Average pH of vegetation leachate was higher in throughfall but lower in stemflow than open rain and higher in Quercus variabilis forest than in Pinus rigida forest. The flow of $SO{_4}^{2-}$, $NO_3{^-}$ and $Cl^-$ through vegetation leaching(throughfall plus stemflow) into soil were 7.2, 4.3, and 2.5 times, respectively, higher in Pinus rigida forest and 4.4, 2, and 2.5 times, respectively, higher in Quercus variabilis forest than in open field. But the concentration of exchangeable cations was 4.1 times higher in Pinus rigida forest and 4.6 times higher in Quercus variabilis forest than in open field. Average pH of soil leachate was lower than that of throughfall, but higher than that of stemflow. The concentration of exchangeable canons and $Al^{3+}$ in soil leachate were more in Pinus rigida forest than in Quercus variabilis forest and increase signficantly with the increase of acidic deposits. Pinus forest had more deposition and canopy interception of acidic pollutants and more nutrient loss than Quercus forest, and Quercus forest had more cation exchange and proton consumption and than consequently had less nutrient loss and better buffer capacity than Pinus forest. The 69% of forest soils was distributed on acidic rock, 25% of it on metamorphic rock, and 6% of it on intermediate and basic rock. Acidic rock residuals which had low very canon exchange capacity and high sensitivity to acid rain occupied a half of total forest land in Taejon area. Therefore forests in Taejon showed high vulnerability to acid rain and will receive much more stress with the increase of acid rain precursors.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.301-312
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• 2013

Landslides are caused by complex interaction among a large number of interrelated factors such as topography, geology, forest and soils. In this study, a comparative study was carried out using fuzzy relationship method and artificial neural network to evaluate landslide susceptibility. For landslide susceptibility mapping, maps of the landslide occurrence locations, slope angle, aspect, curvature, lithology, soil drainage, soil depth, soil texture, forest type, forest age, forest diameter and forest density were constructed from the spatial data sets. In fuzzy relation analysis, the membership values for each category of thematic layers have been determined using the cosine amplitude method. Then the integration of different thematic layers to produce landslide susceptibility map was performed by Cartesian product operation. In artificial neural network analysis, the relative weight values for causative factors were determined by back propagation algorithm. Landslide susceptibility maps prepared by two approaches were validated by ROC(Receiver Operating Characteristic) curve and AUC(Area Under the Curve). Based on the validation results, both approaches show excellent performance to predict the landslide susceptibility but the performance of the artificial neural network was superior in this study area.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.3
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• pp.29-35
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• 2010

Soil organic carbon (SOC), being a help to forest formation and control of carbon dioxide in the air, is found to be an important factor by which global warming is influenced. Excavating the samples by whole area is very inefficient method to discovering the distribution of SOC. So, the development of suitable model for expecting the relative amount of the SOC makes better use of expecting the SOC. In the present study, a model based on a decision tree algorithm is introduced to estimate the amount of SOC along with accessing influencing factors such as altitude, aspect, slope and type of trees. The model was applied to a real site and validated by 10-fold cross validation using two softwares, See 5 and Weka. From the results given by See 5, it can be concluded that the amount of SOC in surface layers is highly related to the type of trees, while it is, in middle depth layers, dominated by both type of trees and altitude. The estimation accuracy was rated as 70.8% in surface layers and 64.7% in middle depth layers. A similar result was, in surface layers, given by Weka, but aspect was, in middle depth layers, found to be a meaningful factor along with types of trees and altitude. The estimation accuracy was rated as 68.87% and 60.65% in surface and middle depth layers. The introduced model is, from the tests, conceived to be useful to estimation of SOC amount and its application to SOC map production for wide areas.

• Economic and Environmental Geology
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• v.34 no.4
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• pp.385-394
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• 2001

There are serious damage of people and properties every year due to landslides that are occurred by heavy rain. Because these phenomena repeat and the heavy rain is not an atmospheric anomaly, the counter plan becomes necessary. The study area, Ulsan, is one of the seven metropolitan, and largest cities of Korea and has many large facilities such as petrochemical complex and factories of automobile and shipbuilding. So it is necessary assess the landslide hazard potential. In the study. the three steps of landslide hazard assessment techniques such as susceptibility, possibility, and risk were performed to the study area using GIS. For the analyses, the topographic, geologic, soil, forest, meteorological, and population and facility spatial database were constructed. Landslide susceptibility representing how susceptible to a given area was assessed by overlay of the slope, aspect, curvature of topography from the topographic DB, type, material, drainage and effective thickness of soil from the soil DB, lype age, diameter and density from forest DB and land use. Then landslide possibility representing how possible to landslide was assessed by overlay of the susceptibility and rainfall frequency map, Finally, landslide risk representing how dangerous to people and facility was assessed by overlay of the possibil. ity and the population and facility density maps The assessment results can be used to urban and land use plan for landslide hazard prevention.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.1
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• pp.11-20
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• 2010

The distributed rainfall-runoff model which is developed in the country requires a lot of time and effort to generate input data. Also, it takes a lot of time to calculate discharge by numerical analysis based on kinematic wave theory in runoff process. Therefore, most river basins using the distributed model are of limited scale, such as small river basins. However, recently, the necessity of integrated watershed management has been increasing due to change of watershed management concept and discharge calculation of whole river basin, including upstream and downstream of dam. Thus, in this study, the feasibility of the GIS based physical distributed rainfall-runoff model, K-DRUM(K-water hydrologic & hydraulic Distributed RUnoff Model) which has been developed by own technology was reviewed in the flood discharge process for the Geum River basin, including Yongdam and Daecheong Dam Watersheds. GIS hydrological parameters were extracted from basic GIS data such as DEM, land cover and soil map, and used as input data of the model. Problems in running time and inaccuracy setting using the existing trial and error method were solved by applying an auto calibration method in setting initial soil moisture conditions. The accuracy of discharge analysis for application of the method was evaluated using VER, QER and Total Error in case of the typhoon 'Ewiniar' event. and the calculation results shows a good agreement with observed data.

• Journal of Korea Water Resources Association
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• v.38 no.5 s.154
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• pp.391-399
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• 2005

The purpose of this study is to evaluate hydrological impact by the land cover change of typhoon damage. For the typhoon RUSA (rainfall 1,402 mm) occurred in 2002 (August $31\;{\sim}$ September 1), satellite images of Landsat 7 ETM+ of September 29, 2000 and Landsat 5 TM of September 11, 2002 were selected, and each land cover was classified for Namdae-cheon watershed $192.7km^2$ located in the middle-eastern part of Korea Peninsula. SCS unit hydrograph for watershed runoff and Muskingum for streamflow routing of WMS HEC-1 was adopted. 30m resolution DEM & hydrological soil group using 1:50,000 soil map were prepared. The model was calibrated using three available data of storm events of 1985 to 1988 based on 1985 land cover condition. To predict the streamflow change by damaged land cover condition, rainfall of 50 years to 500 years frequency were generated using 2nd quantile of Huff method. The damaged land cover condition treated as bare soil surface increased streamflow of $50.1\;m^3/sec$ for 50 years rainfall frequency and $67.6\;m^3/sec$ for 500 years rainfall frequency based on AMC-I condition. There may be some speedy treatment by the government for the next coming typhoon damage.