• Journal of the Korean Ceramic Society
• /
• v.48 no.1
• /
• pp.20-25
• /
• 2011

Since 1980's, many mines have been closed and abandoned due to the exhaustion of deposits and declining prices of international mineral resources. Because of the lack of post management for these abandoned mines, Farm land and rivers were contaminated with heavy metal ions and sludge. We studied on the solidification/stabilization of heavy metal ions, chromium ions and lead ions, using magnesia-phosphate cement. Magnesia binders were used calcined-magnesia and dead-burned magnesia. Test specimens were prepared by mixing magnesia binder with chromium ions and lead ions and activators. We analyzed the hydrates by reaction between magnesiaphosphate cement and each heavy metal ions by XRD and SEM-EDAX, and analyzed the content of heavy metal ions in the eruption water from the specimens for the solidification and stabilization of heavy metal ions by ICP. The results was shown that calcined magnesia binder is effective in stabilization for chromium ions and dead-burned magnesia binder is effective in stabilization for lead ions.

• Journal of Ecology and Environment
• /
• v.29 no.2
• /
• pp.143-149
• /
• 2006

This study was conducted to identify native ectomycorrhizal (ECM) fungi colonizing Pinus densiflora for revegetation of abandoned coal mines in Korea. Seedlings of P. densiflora growing on coal mining spoils of a study site in Samcheok were collected. ECM roots were observed under stereomicroscope and their DNA were extracted from each root tip for a seedling for molecular identification. A PCR primer pair specific to fungi, ITS1F and ITS4, was used to amplify fungal DNA. Restriction enzymes, Alul and Hinfl were used for restriction fragment length polymorphism (RFLP). Combined with RFLP profiles and sequence analysis, total twenty one taxa were identified from the ECM root tips. Basidiomycetous fungi including Thelephoraceae, Pezizales, Laccaria, Pisolithus and Ascomycetous fungi including ericoid mycorrhizal fungi were identified from this study. Results showed that the most frequently found in the study sites was a species in Thelephoraceae. A possible use of ECM fungi identified in this study for the revegetation of abandoned coal mines with P. densiflora was discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.12
• /
• pp.4987-5014
• /
• 2015

The bilinear pairing, also known as Weil pairing or Tate pairing, is widely used in cryptography and its properties help to construct cryptographic schemes for different applications in which the security of the transmitted data is a major concern. In remote login authentication schemes, there are two major requirements: i) proving the identity of a user and the server for legitimacy without exposing their private keys and ii) freedom for a user to choose and change his password (private key) efficiently. Most of the existing methods based on the bilinear property have some security breaches due to the lack of features and the design issues. In this paper, we develop a new scheme using the bilinear property of an elliptic point and the biometric characteristics. Our method provides many features along with three major goals. a) Checking the correctness of the password before sending the authentication message, which prevents the wastage of communication cost; b) Efficient password change phase in which the user is asked to give a new password after checking the correctness of the current password without involving the server; c) User anonymity - enforcing the suitability of our scheme for applications in which a user does not want to disclose his identity. We use BAN logic to ensure the mutual authentication and session key agreement properties. The paper provides informal security analysis to illustrate that our scheme resists all the security attacks. Furthermore, we use the AVISPA tool for formal security verification of our scheme.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2002.09a
• /
• pp.75-80
• /
• 2002

Enormous volumes of mining wastes from the abandoned and closed mines are disposed without a proper treatment at Southeastern part of Kangwon Province. Erosion of these wastes contaminates soil, surface water, and sediments with heavy metals. Objectives of this research were to fractionate heavy metals in the mine waste and to assess the potential S. P. A. G.(Soil Pollution Assesment Guidance) of each metal fraction. Mine wastes analyzed for physical and chemical properties. pH of wastes ranged from 3.3 to 8.0. Contents of total N and loss on ignition matter were in the ranges of 0.2~5.6%, and 0.8~15.3%, respectively. Heavy metals in the wastes were higher in the coal mines than those in the other mine wastes. Total concentrations of metals in the wastes were in the orders of Pb > Zn > Cu > Cd, exceeded the corrective action level of the Soil Environment Conservation Law and higher than the natural abundance levels reported from uncontaminated soils. Relative distribution of heavy metal fractions was residual > organic > reducible > carbonate > adsorbed, reversing the degree of metal bioavailability. Mobile fractions of metals were relatively small compared to the total concentrations. Soil Pollution Assesment Guidance(SPAG) values were ranged from 0.08 to 9.14 based on labile fraction of metal concentrations. SPAG values of labile concentration were lower than those of total concentration.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.09a
• /
• pp.48-58
• /
• 2004

Objectives of this research were to reclaim the coal mine overburdens using the lime waste cake from the soda ash production by stabilizing the overburden slopes, introducing neutralizing the AMD from runoff and leachate in an attempt find the sink to dispose the lime wastes and alleviate the environmental problems caused by the closed coal mines. The pH changes of the runoff and leachate collected in the tanks at the end of the experimental plots, averaged over measurements from April to August, indicated that the runoff pH of the coal overburden was 4.3 but increased significantly to the ranges of 6.7 to 7.1 with treatments of tile calcites and lime wastes. This might be related with the decreases in Fe concentrations in the runoff and leachate from the coal overburdens. The Fe concentrations in tile runoff seemed to increase with the amounts of precipitation. Results demonstrated that the amounts of lime wastes at 25% of the lime requirement were sufficient for neutralizing the acidic coal overburden. Either layering between the coal waste and topsoil or mixing with coal overburdens could be adopted as the lime waste treatment method. The lime wastes from the soda ash production might have a potential to be recycled for the reclamation of the abandoned coal mines to alleviate the environmental problems associated with coal mine waste.

• Journal of Soil and Groundwater Environment
• /
• v.23 no.1
• /
• pp.63-73
• /
• 2018

Rice is a staple food source in Asian countries. In paddy field, rice plant can take up toxic elements through its roots from contaminated soils, and its leaves and grain can absorb the toxic elements deposited on the soil surface. A totla of 40 soil and polished rice samples were collected around four abandoned metal mines in Korea and analyzed for As, Cd, Cu, Pb and Zn by atomic absorption spectrophotometer (AAS). The average contents of As, Cd, Cu, Pb and Zn in rice grain grown on the contaminated soils were 0.247, 0.174, 4.694, 0.804 and 16.78 mg/kg, respectively. These levels are higher than worldwide average concentrations. Assuming the rice consumption of 169 g/day by overall households in Korea, the estimated daily intakes from the rices were found to be 33, 48, and 63% for As, Cd, and Pb, respectively, of the acceptable daily intake (ADI) suggested by the FAO/WHO Joint Food Additive and Contaminants Committee.

• Progress in Superconductivity and Cryogenics
• /
• v.18 no.1
• /
• pp.28-32
• /
• 2016

There are a few thousand abandoned metal mines in South Korea. The abandoned mines cause several environmental problems including releasing acid mine drainage (AMD), which contain a very high acidity and heavy metal ions such as Fe, Cu, Cd, Pb, and As. Iron oxides can be formed from the AMD by increasing the solution pH and inducing precipitation. Current study focused on the formation of iron oxide in an AMD and used the oxide for adsorption of heavy metals. The heavy metal adsorbed iron oxide was separated with a superconducting magnet. The duration of iron oxide formation affected on the type of mineral and the degree of magnetization. The removal rate of heavy metal by the adsorption process with the formed iron oxide was highly dependent on the type of iron oxide and the solution pH. A high gradient magnetic separation (HGMS) system successfully separated the iron oxide and harmful heavy metals.

• Earthquakes and Structures
• /
• v.11 no.6
• /
• pp.1143-1164
• /
• 2016

Time Delay of Arrival (TDOA) estimation methods based on correlation function analysis play an important role in the micro-seismic event monitoring. It makes full use of the similarity in the recorded signals that are from the same source. However, those methods are subjected to the noise effect, particularly when the global similarity of the signals is low. This paper proposes a new approach for micro-seismic monitoring based on cross wavelet transform. The cross wavelet transform is utilized to analyse the measured signals under micro-seismic events, and the cross wavelet power spectrum is used to measure the similarity of two signals in a multi-scale dimension and subsequently identify TDOA. The offset time instant associated with the maximum cross wavelet transform spectrum power is identified as TDOA, and then the location of micro-seismic event can be identified. Individual and statistical identification tests are performed with measurement data from an in-field mine. Experimental studies demonstrate that the proposed approach significantly improves the robustness and accuracy of micro-seismic source locating in mines compared to several existing methods, such as the cross-correlation, multi-correlation, STA/LTA and Kurtosis methods.

• Journal of Soil and Groundwater Environment
• /
• v.15 no.3
• /
• pp.27-33
• /
• 2010

The purpose of this study was in search of native plant species showing metal-resistant property and excessively accumulating heavy metals in metal-contaminated soil or abandoned mines as well as in evaluation of applicability of phytoremediation. In the study area, species showing excessively accumulating heavy metals were a shepherd´s purse, pampas grass, a Korean lettuce, a Hwansam vine, the Korean persicary, a foxtail, a goosefoot, and a water pepper. The first screened plant species in Sambo mine were as shepherd's purse, Korean lettuce and pampas grass Among them the shepherd´s purse can be excluded because it is a seasonal plant and has lower removal capacity for heavy metals. The Korean lettuce was also excluded because of having lower removal capacity for heavy metals. Pampas grass is a highly bionic plant species constantly growing from spring. However it has weak points such as little accumulation capacity for zinc as well as small values of an accumulation factor and a translocation factor. Another problem is regarded as removal of roots after the clean up if pampas grass is applied to a farmland. In Sanyang mine, wormwood and Sorijaengi were considered as adaptable species.

• Geomechanics and Engineering
• /
• v.1 no.2
• /
• pp.143-154
• /
• 2009

Many factors influence occurrences of rock burst in coal mines, such as mining methods, control methods of the coal roof, lithological characteristics of the roof and floor, tectonic stress, groundwater and so on. Among those factors, lithological characteristics in the roof are the intrinsic controlling factors that affect rock burst during coal mining. Tangshan colliery is one of the coal mines that have suffered seriously from rock bursts in China. In this paper, based on the investigating the lithological characteristics of coal roofs and occurrence of rock bursts in Tangshan colliery, a numerical method is used to study the influence of roof lithological characteristics on rock burst potential. The results show that the lithological characteristics in the roof have an important impact on the distributions of stresses and elastic strain energy in coal seams and their surrounding rocks. Occurrences of rock bursts in this colliery have a close correlation with the thick-bedded, medium- to fine-grained sandstones in the roof. Such strata can easily cause severe stress concentration and accumulate enough energy to trigger rock bursts in the working face during mining operations.