• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.5
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• pp.60-71
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• 2008

Through analyzing the specific physicochemical alterations in depth-based soil at reclaimed dredging area, the baseline data were provided for developing the reclaimed dredging area as natural landscape planting sites and ecological-landscape sites based on the soil improvement technology. There was no physical disturbance for 15 to 20 years in Gwangyang Bay reclaimed dredging area after reclamation. Physicochemical examinations of the soil were performed based on the vertical depth. Results of physicochemical analysis such as pH, electric conductivity, total salt contents, silt, clay contents, available phosphorus, calcium, magnesium, sodium, chlorine, and sodium-adsorption ratio showed increasing patterns with the depth while total organic contents, total nitrogen, and sand showed decreasing patterns. Potassium as an exchangeable cation, showed similar distribution patterns between the shallow and deep soil. This result strongly implied that long-term exposure to natural rainfall in reclaimed dredging area altered soil characteristics related to salinity. This research demonstrated that there were no remarkable differences in physicochemical characteristics at soil depth and groundwater table height, suggesting a baseline data for developing reclaimed dredging area. Additional investigation is required for different reclaimed dredging areas. Also, additional monitoring and examination are need on plant communities and time variable alteration in the soil to test the feasibility of reclaimed dredging areas as natural landscape planting sites and ecological-landscape sites.

• Geophysics and Geophysical Exploration
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• v.7 no.1
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• pp.62-69
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• 2004

The objective of this study is to estimate the distribution of a zone disturbed by excavation (EDZ) around tunnels that have been excavated at about 500 m depth in pre-Tertiary hard sedimentary rock. One of the most important tasks is to evaluate changes in the dynamic stability and permeability of the rock around the tunnels, by investigating the properties of the rock after the excavation. We performed resistivity and acoustic tomography using two boreholes, 5 m in length, drilled horizontally from the wall of a tunnel in pre-Tertiary hard conglomerate. By these methods, we detected a low-resistivity and low-velocity zone 1 m in thickness around the wall of the tunnel. The resulting profiles were verified by permeability and evaporation tests performed at the same boreholes. This anomalous zone matched a high-permeability zone caused by open fractures. Next, we performed resistivity monitoring along annular survey lines in a tunnel excavated in pre-Tertiary hard shale by a tunnel-boring machine (TBM). We detected anomalous zones in 2D resistivity profiles surrounding the tunnel. A low-resistivity zone 1 m in thickness was detected around the tunnel when one year had passed after the excavation. However, two years later, the resistivity around the tunnel had increased in a portion, about 30 cm in thickness, of this zone. To investigate this change, we studied the relationship between groundwater flow from the surroundings and evaporation from the wall around the tunnel. These features were verified by the relationship between the resistivity and porosity of rocks obtained by laboratory tests on core samples. Furthermore, the profiles matched well with highly permeable zones detected by permeability and evaporation tests at a horizontal borehole drilled near the survey line. We conclude that the anomalous zones in these profiles indicate the EDZ around the tunnel.

• 한국지구물리탐사학회:학술대회논문집
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• 2001.09a
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• pp.104-121
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• 2001

Recently, the pollution of soil and groundwater becomes a serious social problem, and geophysical exploration methods have been introduced as a remedial investigation method of subsurface. Digital technologies such as personal computer have revolutionized our ability to acquire large volume of data in a short term, and to produce more reliable results for subsurface image. Also, color graphics easily visualizes the survey results in a more understandable manner, and it is widely used for not only characterizing the contaminated subsurface but also monitoring contaminant and remedial process. In this paper, electrical resistivity and electromagnetic (EM) surveys were carried out in order to understand characteristics of waste landfills, and the applicability of geophysical prospecting to site assessment of waste landfill was also tested. According to the result, electrical resistivity and electromagnetic (EM) surveys were effective in estimating distribution of the leachate plume.

• 한국지구물리탐사학회:학술대회논문집
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• 1999.08a
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• pp.1-20
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• 1999

In Japan, geophysical exploration methods have been widely applied to civil engineering and construction fields for a long time. In particular, seismic refraction has long played a significant role in geotechnical site investigations for tunnels, dams and landslides. However, our growing interest on the social and natural environment makes the methods available and its application fields diversify. Digital technologies such as personal computer have revolutionized our ability to acquire large volumes of data rapidly, and to produce more reliable results for subsurface image. Also, color graphics easily visualizes survey results In a more understandable manner, These days geophysical methods are essential to assessing grouting effects, predicting the front of tunnel cutting face, monitoring the movement, pollution and purification process of groundwater. Now three-dimensional exploration techniques have developed for the site characterization in civil engineering and construction needs.

• Tunnel and Underground Space
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• v.30 no.2
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• pp.149-163
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• 2020

This paper presents a logistic regression and GIS based urban ground sink susceptibility assessment using underground facility information considering soil particle loss. In the underground environment, the particle loss due to water flow or groundwater level change leads to the occurrence and expansion of cavities, which directly affect the ground sink. Four different contributory factors were selected according to the two underground facility domains (water pipeline area, sewer pipeline area) and subway line area. The logistic regression method was used to analyze the correlation and to derive the regression equation between the ground sink inventory and the contributory factors. Based on these results, three ground sink susceptibility maps were generated. The results obtained from this study are expected to provide basic data on the area susceptible to ground sink and needed to safety monitoring.

• Tunnel and Underground Space
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• v.16 no.3 s.62
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• pp.195-202
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• 2006

Hydro-environmental impact assessments (HEIA) in tunnel constructions have been performed through various methods including preliminary investigations, field tests, numerical simulations, and monitoring. Specially, it is very important to evaluate quantitatively groundwater inflows into tunnels as well as drawdowns caused by tunnelling. Obvious definitions between porous and fractured rock media in hvdrogeologic properties of study regions must be needed to execute HEIA for rational tunnel construction in fractured bedrocks. In this paper, we propose a HEIA on tunnel constructions in fractured rocks media resulted from various hydrogeologic field tests and numerical models on given regions and determination of systematic order, i.e. the technical road map (TRM) of HEIA. These systematic HEIAs are expected to be usefully applied to base data in tunnel construction in fractured rock media.

• Journal of Korean Society of Forest Science
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• v.108 no.2
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• pp.233-240
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• 2019

The aim of this study was to provide basic data that could identify and help prevent a slow-moving landslide using an analysis of the relationship between below-ground characteristics and water from three slow-moving landslide areas in Pohang, Gyeongsangbuk-do, South Korea. Surface surveys, resistivity, seismic exploration, well logging, and boring surveys were conducted in the three areas. The main direction of discontinuous surface was matched with the slope direction of the three landslides. The results indicatedthat slow-moving landslides might occur in the direction of the slope. Underground water was distributed within the crush zones within the three landslide areas and flowed along the tensile cracks. There was a significant difference (p<0.01) between the mean angle of the tensile cracks and that of the underground waterflow (p=0.8019). These results indicated that the progress of a slow-moving landslide can be forecast by monitoring the location and flow of underground water within a known slow-moving landslide area.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.1057-1069
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• 2020

For most upland crops in Korea, underground water is used to ensure an adequate water supply. Thus, surface water storage tanks are needed to supply surface water from reservoirs or streams. This study discusses the design, manufacture and monitoring of a water storage tank capable of reliably supplying water to crops and preventing the inflow of floating debris. The study was conducted in an apple orchard in Yesan-gun, Chungcheongnam-do in Korea. Based on the water requirements of the crops and size of the orchard, a required flow volume of about 0.6 ㎥·h-1 was determined, along with a surface water storage tank capacity of 1.2 ㎥. Following a comparison with other materials, stainless steel (STS) was used to construct the water tank. The tank was designed to provide 14 hours of irrigation, enabling a small-capacity, cost-efficient tank design to be used. A surface water irrigation test was performed using the surface water storage tank. The average surface water irrigation flow rate was 0.00045 ㎥·m-2·h-1. The water quality test showed that the pH, suspended solids (SS), total nitrogen (TN), and total phosphorus (TP) values satisfied the reference values for agricultural water. The test results showed that the surface water storage tank evaluated in this study allows for crop irrigation when there is a lack of groundwater during droughts.

• Biomedical Science Letters
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• v.27 no.1
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• pp.35-43
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• 2021

Human Sapovirus (HuSaV) is one of the major causes of acute gastroenteritis in humans, and it is used as a molecular diagnostic technique based on polymerase chain reaction (PCR) from humans, food, shellfish, and aquatic environments. In this study, the HuSaV diagnosis technique was used in an aquatic environment where a number of PCR inhibitors are included and pathogens, such as viruses, are estimated to exist at low concentration levels. HuSaV-specific primers are improved to detect 38 strains registered in the National Center for Biotechnology Information (NCBI). The established optimal condition and the composition, including the RT-nested PCR primers and SL® Non-specific reaction inhibitor, were found to have 100 times higher sensitivity based on HuSaV plasmid than the previously reported methods (100 ag based on HuSaV plasmid 1 ng/μL). Through an artificial infection test, the developed method was able to detect at least 1 fg/μL of HuSaV plasmid contaminated with total nucleic acid extracted from groundwater. In addition, RT-nested PCR primer sets for HuSaV detection can react, and a positive control is developed to verify false positives. This study is expected to be used as a HuSaV monitoring method in the future and applied to the safety response to HuSaV from water environments.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1-7
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• 2007

New Zealand is a hydrologically diverse and active country. This paper presents an overview of the major hydrological issues and problems facing New Zealand and provides examples of some the research being undertaken to solve the problems. Fundamental to any environmental decision making is the provision of good quality hydrometric data. Reduced funding for the national hydrometric network has meant a reduction in the number of monitoring sites, the decision on how to redesign the network was made using information on geographic coverage and importance of each site. New Zealand faces a major problem in understanding the impacts of rapid land use change on water quantity and quality. On top of the land use change is overlain the issue of agricultural intensification. The transfer of knowledge about impacts of change at the small watershed scale to much larger, more complex watersheds is one that is attracting considerable research attention. There is a large amount of research currently being undertaken to understand the processes of water and nutrient movement through the vadose zone into groundwater and therefore understanding the time taken for leached nutrients to reach receiving water bodies. The largest water management issue of the past 5 years has been based around fair and equitable water allocation when there is increasing demand for irrigation water. Apart from policy research into market trading for water there has been research into water storage and transfer options and improving irrigation efficiency. The final water management issue discussed concerns the impacts of hydrological extremes (floods and droughts). This is of particular concern with predictions of climate change for New Zealand suggesting increased hydrological extremes. Research work has concentrated on producing predictive models. These have been both detailed inundation models using high quality LIDAR data and also flood models for the whole country based on a newly interpolated grid network of rainfall.