• Journal of Korean Society of Water and Wastewater
• /
• v.34 no.6
• /
• pp.503-512
• /
• 2020

Identifying the water circulation status is one of the indispensable processes for watershed management in an urban area. Recently, various water circulation models have been developed to simulate the water circulation, but it takes a lot of time and cost to make a water circulation model that could adapt the characteristics of the watershed. This paper aims to develop a water circulation state estimation model that could easily calculate the status of water circulation in an urban watershed by using multiple linear regression analysis. The study watershed is a watershed in Seoul that applied the impermeable area ratio in 1962 and 2000. And, It was divided into 73 watersheds in order to consider changes in water circulation status according to the urban characteristic factors. The input data of the SHER(Similar Hydrologic Element Response) model, a water circulation model, were used as data for the urban characteristic factors of each watershed. A total of seven factors were considered as urban characteristic factors. Those factors included annual precipitation, watershed area, average land-surface slope, impervious surface ratio, coefficient of saturated permeability, hydraulic gradient of groundwater surface, and length of contact line with downstream block. With significance probabilities (or p-values) of 0.05 and below, all five models showed significant results in estimating the water circulation status such as the surface runoff rate and the evapotranspiration rate. The model that was applied all seven urban characteristics factors, can calculate the most similar results such as the existing water circulation model. The water circulation estimation model developed in this study is not only useful to simply estimate the water circulation status of ungauged watersheds but can also provide data for parameter calibration and validation.

• Journal of the Korean GEO-environmental Society
• /
• v.12 no.7
• /
• pp.49-56
• /
• 2011

Recently, the ground injection method using water glass as one of the components of the main resources and the products of the construction has some basic problems for permanent reinforcement of foundation and stopping leakage of water because it has some serious problems such as durability reduction, compression strength reduction and eluviation. This study was to evaluate the environmental impact and durability of the developed friendliness of Natural and Durable Stabilizer(NDS) of inorganic injection and Space Grouting Roket(SGR) with typical water glass type material. Two materials, NDS and SGR, were compared with each other by unconfined compressive strength test, fish poison test, durability test and triaxial permeability test. The results of the durability test indicated that the 28-day strength of the NDS was 1.5 times higher than that of the SGR. The fish poison test proved that the survival rate in the SGR and NDS is 50~70%, and 100%, respectively. Therefore, the NDS has higher survival rate than that of the existing SGR. The NDS will be considered by an environmentally friendly product and moreover it has a few problems for soil and groundwater pollution.

• Journal of the Korean GEO-environmental Society
• /
• v.12 no.11
• /
• pp.51-57
• /
• 2011

The calcium hydroxide($Ca(OH)_{2}$) which is flowed into the deteriorated tunnel by groundwater is reacted with carbon dioxide($CO_{2}$) and the vehicle's exhaust gas ($SO_{3}$). So its by-products are precipitated at the drainage pipe and these cause the drainage clogging. Most by-products are composed of $CaCO_{3}$ with calcite from a chemical experiment. The purpose of this study is mainly focused on comparison of attachment on each material of drainage pipe (teflon-coated steel pipe, silicon-Oil coated pipe, acrylic pipe and PVC pipe). The test was progressed to disembogue the CaO aqueous solution and tunnel outflow into each of the pipes. The experimental results show that the most produced scale pipe is PVC material and the followings are Acrylic pipe, Silicon-Oil coating pipe and Teflon coating pipe. But the long-term test results showed that teflon-coated steel pipe had a problem with durability because soil which was contained in the tunnel outflow occurred detachment of coating and corrosion of the steel pipe.

• Journal of the Korean Geotechnical Society
• /
• v.37 no.1
• /
• pp.29-41
• /
• 2021

Although underground works are essential to use underground spaces in urban areas efficiently, various damages caused by constructions have often occurred, making them major social problems. Since 2018, it is stipulated in the Special Act on Underground Safety Management that appropriate construction methods must be used in the design stage to prevent various damage cases. This Special Act includes establishing an area subject to underground safety impact assessment, analysis of ground and geological status, review of effects caused by changes in groundwater, review of ground safety, and establishment of measures to secure underground safety. This study area consists of various strata in order of landfill, sedimentary silt, sedimentary sand, sedimentary gravel, weathering zone, and foundation rock. Also, the slurry wall, a highly rigid underground continuous wall, was chosen as a construction method to consider high water table distribution and minimize the influence of the surroundings in this area. However, ground subsidence occurred on the road nearby in December 2019 due to the inflow of loosening soil to the construction area. Thus, several types of site investigations were conducted to suggest an appropriate analysis method and to find out loosed ground behavior and its area for the subsided site. As a result, new design soil properties were re-calculated, and the reinforcement measures were proposed through analytical verification.

• Geophysics and Geophysical Exploration
• /
• v.24 no.3
• /
• pp.73-77
• /
• 2021

Induced polarization (IP) is useful for mineral exploration and hydrogeological studies by visualizing the electrochemical reactions at the interface between polarized minerals and groundwater. Frequency-domain IP (FDIP) is not actively applied to field surveys because it takes longer to acquire data, despite its higher data quality than conventional time-domain IP. However, data quality is more important in current mineral exploration as the targets gradually shift to deep or low-grade ore bodies. In addition, the measurement time reduced by automated instrumentation increases the potential for FDIP field applications. Therefore, we demonstrate that FDIP can detect mineral exploration targets by performing geophysical logging in the boreholes of a skarn deposit, in South Korea. Alternating current (AC) resistivity, percent frequency effect (PFE) and metal factor (MF) were calculated from impedance values obtained at two different frequencies. Skarn zones containing magnetite or pyrite showed relatively low AC resistivity, high PFE, and high MF compared to other zones. Therefore, FDIP surveys are considered to be useful for mineral exploration.

• Journal of Environmental Impact Assessment
• /
• v.30 no.4
• /
• pp.215-224
• /
• 2021

In this study, to investigate the effect of stabilization of Pb-contaminated soil near a smelter site for the reduction of environmental risk of Pb leaching, commercial stabilizers were amended with the Pb-contaminated soil and evaluated leaching characteristics of Pb in soil by TCLP and SPLP leaching test. Also, performing sequential extraction procedure speciation of Pb in the amended soil was investigated. Limestone, AC-2 (Amron), Metafix (Peroxychem) that possess stabilization performance towards heavy metal in soil and mass production is available were selected as candidates. AC-2 contained a CaCO₃ and MgO crystalline phase, while Metafix had a Fe₇S₈ crystalline phase, according to XRD studies. Pb content in SPLP extract was lower than the South Korean drinking water standard for Pb in groundwater at 4% AC-2 and Metafix treatment soil, and TCLP-based stabilization effectiveness was more than 90%. The findings of the sequential extraction method of soil treated with Metafix revealed that fractions 1 and 2 of Pb, which correspond to relatively high mobility and bioavailable fractions, were lowered, while the residual fraction (fraction 5) was raised. As a consequence, the order of performance for Pb stabilization in polluted soil was Metafix>AC-2>limestone.

• Geophysics and Geophysical Exploration
• /
• v.24 no.4
• /
• pp.202-208
• /
• 2021

Induced polarization (IP) was first published in a Korean academic journal in 1973, and it was soon applied to coal and metal ore exploration. Then, in universities and research institutes, IP modeling studies using the finite element approach and experimental studies on IP responses for artificial samples were conducted. In the mid-1980s, the spectral IP (SIP) measurement module was introduced to Korea, and physical scale modeling and inversion approaches were developed. Due to the decline of the mineral resource industry, this method was not actively applied. However, the SIP method was not applied In the 1990s, IP exploration was applied in the investigation of hydrothermal deposits of sulfide minerals and bentonite mineralization zones, as well as to areas where the groundwater was contaminated by intruding seawater. In the 2000s, three-dimensional inversion of the IP approach was developed, and high-precision geophysical exploration was required to secure domestic and overseas mineral resources, so SIP experiments on rock samples and approaches for field exploration were developed. The SIP approach was proven useful for the exploration of metal deposits containing sulfide minerals by applying it to explore the mineralization zone of gold-silver deposits in the Haenam region. The IP method is considered to be effective in exploring critical minerals (lithium, cobalt, and nickel) in high-tech industries. It also is expected to be useful for environmental and geotechnical investigations.

• Economic and Environmental Geology
• /
• v.54 no.6
• /
• pp.659-670
• /
• 2021

In this study, we analyzed changes in policies after the Korean New Deal Policy in 2020, metaverse and 6th generation communication technology. In the research and development of geoscience and mineral resources, we emphasized on the connection between smart cities and digital twins by focusing on the linkage of the real world and geo-information. Further, we examined trends in developing digital twins after the Korean New Deal Policy in 2020 that focused on three-dimensional visualization technology, the first stage in implementing digital twins, and real-time monitoring technology of underground information, the second implementing stage. As results of this study, we emphasized on the efforts to provide accurate underground information based on geology, groundwater and geo-environment and to analyze and predict near-real-time levels of available underground information to the industry, local governments and the central governments. Research and development that integrate the fields of geology, environment, and information is required to lead national digital twin policies and smart city policies owing to the acceleration of the digital economy in Korea and globally during the post-Corona era.

• Tunnel and Underground Space
• /
• v.32 no.2
• /
• pp.107-119
• /
• 2022

Excavation-Disturbed Zone (EDZ) is an important design factor in constructing final disposal facilities for spent nuclear fuel, since EDZ affects mechanical stability including a spacing between disposal holes, and the hydraulic properties within EDZ plays a significant role in estimating in-flow rate of groundwater as well as a subsequent corrosion rate of a canister. Thus, it is highly required to characterize in-situ EDZ with precision and control the EDZ occurrence while excavating disposal facilities and constructing relevant underground research facilities. In this report, we not only reviewed EDZ-related researches carried out in the ONKALO facility of Finland but also examined appropriate methods for field inspection and quality control of EDZ occurrence. From the review, GPR can be the most efficient method for in-situ characterization of EDZ since it does not demand drilling a borehole that may disturb a surrounding environment of caverns. And the EDZ occurrence was dominant at a cavern floor and it ranged from 0 to 70 cm. These can provide useful information in developing necessary EDZ-related regulations for domestic disposal facilities.

• Journal of the Korean Geotechnical Society
• /
• v.38 no.10
• /
• pp.49-60
• /
• 2022

Underground urbanization appears to be a promising solution in response to the shortage of construction sites in the above-ground space. In this context, an accurate evaluation of a construction site ensures the long-term performance of geosystems. This study characterizes potential sites for complex plants built in underground space using geophysical methods (i.e., seismic refraction exploration and electrical resistivity survey) and in situ tests (i.e., standard penetration tests (SPTs) and downhole tests). SPTs are conducted in nine boreholes BH-1-BH-9 to estimate the groundwater level and vertical distribution of geological structures. The seismic refraction method enables us to obtain the elastic wave velocity and thickness of each soil layer for each cross-sectional area. An electrical resistivity survey conducted using the dipole array method provides the electrical resistivity profiles of the cross-sectional area. Data obtained using geophysical techniques are used to assess the classification of the soil layer and bedrock, particularly the fracture zone. This study suggests that geotechnical information using in situ tests and geophysical methods are useful references to design an underground complex plant construction.