• The Journal of Engineering Geology
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• v.32 no.2
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• pp.257-270
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• 2022

This study evaluated the hydraulic factors contributing to the decreasing groundwater levels across Jeju island. Time-series data for groundwater level, precipitation, and groundwater usage and information on land use were acquired, and the correlations among them were analyzed to evaluate the causes of the decreasing groundwater. The effects of precipitation and groundwater usage on the fluctuations of groundwater level were quantified using response surface analysis and sensitivity analysis, and methods for groundwater quantity management by region were proposed. The results showed that the rate of groundwater decrease in the western region was larger than that in the eastern region. For the eastern region, the influence of precipitation was large and the rate of decrease in the groundwater level was relatively small. The geological formation of this part of the island and continuous seawater intrusion suggest that although the absolute amount of groundwater extracted for use was large, the decrease in the groundwater level was not seen to be great due to an increase in pressure by seawater intrusion. Overall, precipitation and groundwater usage had the greatest effect on the amount of groundwater in the western region, and thus their data would be most useful for informing groundwater management, whereas other factors (e.g., sea level and the location of the freshwater-seawater transition zone) must be considered when understanding Jeju's eastern region. As the characteristics of groundwater level fluctuations in the eastern and western regions are distinct, an optimal management plan for each region should be proposed to ensure the efficient management of groundwater quantity.

• Korean Journal of Remote Sensing
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• v.36 no.6_2
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• pp.1523-1535
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• 2020

In order to produce crop information using remote sensing, we use classification and growth monitoring based on crop phenology. Therefore, time-series satellite images with a short period are required. However, there are limitations to acquiring time-series satellite data, so it is necessary to use fusion with other earth observation satellites. Before fusion of various satellite image data, it is necessary to overcome the inherent difference in radiometric characteristics of satellites. This study performed Korea Multi-Purpose Satellite-3 (KOMPSAT-3) cross calibration with Landsat-8 as the first step for fusion. Top of Atmosphere (TOA) Reflectance was compared by applying Spectral Band Adjustment Factor (SBAF) to each satellite using hyperspectral sensor band aggregation. As a result of cross calibration, KOMPSAT-3 and Landsat-8 satellites showed a difference in reflectance of less than 4% in Blue, Green, and Red bands, and 6% in NIR bands. KOMPSAT-3, without on-board calibrator, idicate lower radiometric stability compared to ladnsat-8. In the future, efforts are needed to produce normalized reflectance data through BRDF (Bidirectional reflectance distribution function) correction and SBAF application for spectral characteristics of agricultural land.

• Journal of Korean Society on Water Environment
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• v.39 no.3
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• pp.231-239
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• 2023

Public sewage treatment facilities are a necessary infrastructure for public health that treat sewage generated in cities and basin living areas and discharge it into rivers or seas. Recently, the role of public sewage treatment is receiving attention as a place of use of wastewater-based epidemiology (WBE), which analyzes human specific metabolic emissions or biomarkers present in sewage to investigate the environment to which the population is exposed in the water drain. WBE is mainly applied to investigate legal and water-law drug use or to predict and analyze the lifestyle of local residents. WBE has also been applied to predict and analyze the degree of infectious diseases that are prevalent worldwide, such as COVID-19. Since sewage flowing into public sewage treatment facilities includes living information of the population living in the drainage area, it is easy to collect basic data to predict the confirmation and spread of infectious diseases. Therefore, it is necessary to establish a new role of public sewage treatment facilities as an infrastructure necessary for WBE that can obtain information on the confirmation and spread of infectious diseases other than the traditional role of public sewage treatment. In South Korea, the sewerage supply rate is about 95.5% and the number of public sewage treatment facility is 4,209. This means that the infrastructure of sewerage is fully established. However, to successfully drive for WBE , research on monitoring and big-data analysis is needed.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.3
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• pp.69-80
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• 2012

The purpose of this paper was to study the issues related to converting the graveyards within forests into spaces intended for tree burials by means of planting, given the situation that the graveyards have encroached on land and damaged the environment. For the reason, a field survey was performed to determine the width, length, and distance to the nearest tree of 205 graveyards in the capital area. Through this, it was determined that the domestic lands damaged by graveyards amounted to $862km^2$, including the areas that were deforested to manage the graves. This only confirms that land encroachment by graveyards is a serious issue. The methods for making tree burial sites were examined from the perspective of how to meet public demands given the graveyard's spatial distinctiveness. As a result, this study suggested different methods to establish tree burial sites according to the degree of transformation and the term of its formation. This study also classified the graveyards into three types, and identified the planting methods that harmonized the safe growth of trees and the scenic beauty of memorial places based on the standard. This is in order to plant trees that are shade-tolerant and suitable to the forest line, along with which other tree line was and also, to plant aesthetic trees around the empty space. Through applying the developed methods, this study established and monitored two exemplary sites in Yongin and Boryeng. Aesthetic trees were planted in Yongin site which was located in an open area, aod the shade-tolerant trees were planted in Boryeong, which was located in a forest area. As a result, the image of a garden appeared at Yongin site and the image of a tree colony harmonized with the near forest emerged at Boryeong site. Therefore, it is confirmed that the method of planting according to the distribution status of neighboring trees was effective. As a result of monitoring, mulching wood chips were suitable for sites that were small or easy to approach. This is because the weeds were controlled in Yongin site by mulching. Furthermore, by monitoring the growth of 11 species of vegetation, this study confirmed that low and cover-type vegetations were suitable for tree burial sites. In Boryeong site, the wild cherry trees, which were planted as adult trees, all died, and the tilling of snake's beard, which were planted as cover vegetation, was slow. Therefore, this study found that seedlings were more suitable to plant in forest graveyards than adult trees, which were large and difficult to approach, and it was effective to use the remaining lawn and form a low vegetation after the crown of trees had expanded to such places.

• Korean Journal of Remote Sensing
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• v.36 no.6_1
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• pp.1421-1434
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• 2020

The frequency and intensity of heatwaves have been increasing due to climate change. Since urban areas are more severely damaged by heatwaves as they act in combination with the urban heat island phenomenon, every possible preparation for such heat threats is required. Many overseas local governments build heat maps using a variety of spatial information to prepare for and counteract heatwaves, and prepare heatwave measures suitable for each region with different spatial characteristics within a relevant city. Building a heat map is a first and important step to prepare for heatwaves. The cases of heat map construction and thermal environment analysis involve various area distributions from urban units with a large area to local units with a small area. The method of constructing a heat map varies from a method utilizing remote sensing to a method using simulation, but there is no standard for using differentiated spatial information according to spatial scale, so each researcher constructs a heat map and analyzes the thermal environment based on different methods. For the above reason, spatial information standards required for building a heat map according to the analysis scale should be established. To this end, this study examined spatial information, analysis methodology, and final findings related to Korean and oversea analysis studies of heatwaves and urban thermal environments to suggest ways to improve the utilization efficiency of spatial information used to build urban heat maps. As a result of the analysis, it was found that spatial, temporal, and spectral resolutions, as basic resolutions, are necessary to construct a heat map using remote sensing in the use of spatial information. In the use of simulations, it was found that the type of weather data and spatial resolution, which are input condition information for simulation implementation, differ according to the size of analysis target areas. Therefore, when constructing a heat map using remote sensing, spatial, spectral, and temporal resolution should be considered; and in the case of using simulations, the spatial resolution, which is an input condition for simulation implementation, and the conditions of weather information to be inputted, should be considered in advance. As a result of understanding the types of monitoring elements for heatwave analysis, 19 types of elements were identified such as land cover, urban spatial characteristics, buildings, topography, vegetation, and shadows, and it was found that there are differences in the types of the elements by spatial scale. This study is expected to help give direction to relevant studies in terms of the use of spatial information suitable for the size of target areas, and setting monitoring elements, when analyzing heatwaves.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.19-32
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• 2007

In Korea, there have been various methods of estimating groundwater recharge which generally can be subdivided into three types: baseflow separation method by means of groundwater recession curve, water budget analysis based on lumped conceptual model in watershed, and water table fluctuation method (WTF) by using the data from groundwater monitoring wells. However, groundwater recharge rate shows the spatial-temporal variability due to climatic condition, land use and hydrogeological heterogeneity, so these methods have various limits to deal with these characteristics. To overcome these limitations, we present a new method of estimating recharge based on water balance components from the SWAT-MODFLOW which is an integrated surface-ground water model. Groundwater levels in the interest area close to the stream have dynamics similar to stream flow, whereas levels further upslope respond to precipitation with a delay. As these behaviours are related to the physical process of recharge, it is needed to account for the time delay in aquifer recharge once the water exits the soil profile to represent these features. In SWAT, a single linear reservoir storage module with an exponential decay weighting function is used to compute the recharge from soil to aquifer on a given day. However, this module has some limitations expressing recharge variation when the delay time is too long and transient recharge trend does not match to the groundwater table time series, the multi-reservoir storage routing module which represents more realistic time delay through vadose zone is newly suggested in this study. In this module, the parameter related to the delay time should be optimized by checking the correlation between simulated recharge and observed groundwater levels. The final step of this procedure is to compare simulated groundwater table with observed one as well as to compare simulated watershed runoff with observed one. This method is applied to Mihocheon watershed in Korea for the purpose of testing the procedure of proper estimation of spatio-temporal groundwater recharge distribution. As the newly suggested method of estimating recharge has the advantages of effectiveness of watershed model as well as the accuracy of WTF method, the estimated daily recharge rate would be an advanced quantity reflecting the heterogeneity of hydrogeology, climatic condition, land use as well as physical behaviour of water in soil layers and aquifers.

• Korean Journal of Remote Sensing
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• v.30 no.4
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• pp.525-536
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• 2014

In this study, a method to assess and monitor hydrological drought using remote sensing was investigated for use in regions with limited observation data, and was applied to the Upper Namhangang basin in South Korea, which was seriously affected by the 2008-2009 drought. Drought information may be obtained more easily from meteorological data based on water balance than hydrological data that are hard to estimate. Air temperature data at 2 m above ground level (AGL) were estimated using remotely sensed data, evapotranspiration was estimated from the air temperature, and the correlations between precipitation minus evapotranspiration (P-PET) and streamflow percentiles were examined. Land Surface Temperature data with $1{\times}1km$ spatial resolution as well as Atmospheric Profile data with $5{\times}5km$ spatial resolution from MODIS sensor on board Aqua satellite were used to estimate monthly maximum and minimum air temperature in South Korea. Evapotranspiration was estimated from the maximum and minimum air temperature using the Hargreaves method and the estimates were compared to existing data of the University of Montana based on Penman-Monteith method showing smaller coefficient of determination values but smaller error values. Precipitation was obtained from TRMM monthly rainfall data, and the correlations of 1-, 3-, 6-, and 12-month P-PET percentiles with streamflow percentiles were analyzed for the Upper Namhan-gang basin in South Korea. The 1-month P-PET percentile during JJA (r = 0.89, tau = 0.71) and SON (r = 0.63, tau = 0.47) in the Upper Namhan-gang basin are highly correlated with the streamflow percentile with 95% confidence level. Since the effect of precipitation in the basin is especially high, the correlation between evapotranspiration percentile and streamflow percentile is positive. These results indicate that remote sensing-based P-PET estimates can be used for the assessment and monitoring of hydrological drought. The high spatial resolution estimates can be used in the decision-making process to minimize the adverse impacts of hydrological drought and to establish differentiated measures coping with drought.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.4
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• pp.401-409
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• 2003

Recently, the development of underground structures is to be inevitably necessary due to the increase in population and traffic volume that has caused to the limit of urban land use and the heavy traffic jams. Therefore, underground structures such as subway, underground shopping centers, lifeline facilities and so on, have been increasingly constructed, On the other hand, several social problems have occurred during construction, i.e., ground subsidence, noise, and vibration. Therefore, safer and more beneficial methods for underground construction are on the demand. In this research, N.T.R.(New Tubular Roof) method has been modified and utilized for solving those problems and overcoming the difficulties connected with the bored tunnel construction of large underground openings in unfavorable ground, often under the water table, and with overburdens that are too shallow to solve problems of stability using traditional methods. The N.T.R. method has been modified to suit for Korean geotechnical conditions, and was made up for the weak points-the water leakage from walls and tops, the maintenance and the lack of stability-of the conventional methods. This paper dealt with the features and the applicability of N.T.R. Method based on the results from numerical analysis and data from in-situ monitoring system.

• Ecology and Resilient Infrastructure
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• v.3 no.1
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• pp.62-69
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• 2016

Narrow-mouth frog (Kaloula borealis) is the only amphibian species of genus Kaloula living in South Korea. They are designated and managed as endangered class II wildlife by the Ministry of Environment, Korea. Therefore, there is a desperate need of a habitat restoration study to prevent the extinction of narrow-mouth frog. This study is primarily for the purpose of presenting the direction and practical applications to restore damaged narrow-mouth frog habitats or to suggest alternative habitat options. The habitat suitability index (HSI) of narrow-mouth frog was applied to the research area in Mokpo City of Jeollanam-do Province, in order to present a new narrow-mouth frog habitat. We analyzed the research area based on historical contexts, ecological environment, ecology, and habitat requirements. The research area was divided into the core, buffer, and transition zones according to UNESCO MAB (Man and Biosphere) to establish local land-use plans. As for the foundation of the plan, we divided the habitat composition of the core, where narrow-mouth frog live in, into wetland (spawning area), grassland (shelter and feeding grounds), and forestland (feeding ground). We had a comparative analysis of habitat suitability in pre and post planning of narrow-mouth frog habitat restoration. For the validation study of habitat restoration plans, the future research should be on the composition of test-bed, continuous monitoring, and scientific habitat maintenance.

• Journal of the Korean association of regional geographers
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• v.18 no.4
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• pp.473-493
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• 2012

Malaria infection is sensitively influenced by regional meteorological conditions along with global climate change. Remote sensing techniques have become an important tool for extraction of climatic and environmental factors, including rainfall, temperature, surface water, soil moisture, and land use, which are directly linked to the habitat qualities of malaria mosquitoes. Improvement of sensor fidelity with higher spatial and spectral resolution, new multinational sensor development, and decreased data cost have nurtured diverse remote sensing applications in malaria research. In 1984, eradication of endemic malaria was declared in Korea, but reemergence of malaria was reported in mid-1990s. Considering constant changes in malaria cases since 2000, the epidemiological management of the disease needs careful monitoring. Geographically, northmost counties neighboring North Korea have been ranked high in the number of malaria cases. High infection rates in these areas drew special attention and led to a hypothesis that malaria dispersion in these border counties might be caused by north-origin, malaria-bearing adult mosquitoes. Habitat conditions of malaria mosquitoes are important parameters for prediction of the vector abundance. However, it should be realized that malaria infection and transmission is a complex mechanism, where non-environmental factors, including human behavior, demographic structure, landscape structure, and spatial relationships between human residence and the vector habitats, are also significant considerations in the framework of medical geography.