• Journal of Aerospace System Engineering
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• v.13 no.4
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• pp.10-17
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• 2019

This study is concerned with a numerical analysis based on the finite element method to describe the effect of midplane delamination in smart laminated composite plate structures. A new finite element model for centrally located delamination and healthy section was developed and coded in Matlab. The transient analysis of delaminated composite plate with integrated Active Fiber Composite (AFC) was investigated in the present article. The formulation of the governing equation was based on the minimum total potential energy approach. The Newmark time integration technique was employed to solve the differential equations. A parametric study on the effects of boundary conditions and AFC patch location, in presence of delamination on the laminated plate were studied.

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.118-118
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• 2008

The phylogenetic diversity of microbial communities in calcareous mats from Spearfish Creek, a freshwater stream located in the Black Hills of South Dakota, was examined using PCR-based 16S rDNA sequence analysis. In this study, two types of calcareous mats were compared: mature mats formed on the natural substrate of rock surfaces and developing mats on an artificial substrate of glass slides. Among 63 unique isolates from a clone library of 16S rRNA genes from mature mat samples, there were 8 phyla of Bacteria represented. The predominant phylum was Proteobacteria (48%), with the $\beta$ subclass being the largest group. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA genes from slide samples collected at intervals for four months showed considerable diversity of the microbial community from the earliest stages of community development. Amplicons isolated from DGGE gels and sequenced indicated that community succession has occurred without increasing microbial diversity. However, light microscopic analysis revealed a significant increase in microbial cell density throughout the community development. Scanning electron microscopy of mat samples provides evidence that diatoms are also important members of calcareous mat communities.

• Journal of Environmental Health Sciences
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• v.41 no.6
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• pp.369-379
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• 2015

Objectives: The lack of reliable information on environmental pollution and health impacts related to asbestos contamination from abandoned mines has drawn attention to the need for a community health study. This study was performed to evaluate asbestos-related health symptoms among residents near abandoned asbestos mines located in the Chungcheong Provinces. In addition, exposure assessment for asbestos is needed although the exposure to asbestos was in the past. Methods: Past exposure to asbestos among inhabitants near abandoned asbestos mines was estimated by using surface sampling of deposited dust in indoor and outdoor residences. A total of 54 participants were divided into two groups with (34 cases) and without (20 controls) diseases related to asbestos. Surface sampling of deposited dust was carried out in indoor and outdoor residences by collecting 105 samples. Deposited dust for sampling was analyzed by polarization microscope (PLM) and scanning electron microscope?energy dispersive x-ray spectrometer (SEM-EDX) to detect asbestos. Subsequently, the elements of the deposited dust with asbestos were analyzed by SEM-EDX to assess the contribution of sources such as abandoned mines, slate and soil. Results: Among the 105 samples, asbestos was detected by PLM in 29 (27.6%) sampling points, and detected by SEM in 56 (48.6%) sampling points. Asbestos in indoor residences was detected by PLM in four sampling points, and by SEM in 12 sampling points. Asbestos detection in indoor residences may be due to ventilation between indoors and outdoors, and indicates long-term exposure. The asbestos detection rate for outdoor residences in the case group was higher than that in the control group. This can be explained as the case group having had higher exposure to asbestos, and there has been continuous exposure to asbestos in the control group as well as the case group. Conclusion: Past residential asbestos exposure may be associated with asbestosis among local residents near abandoned asbestos mines. Odds ratios were calculated for asbestos detection in outdoor residence by logistic regression analysis. Odds ratio between asbestos detection and asbestosis pulmonum was 3.36 (95% CI 0.90-12.53) (p=0.072), adjusting for age, sex, smoking status and work history with multi-variable logistic regression by PLM analysis method.

• Journal of Environmental Impact Assessment
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• v.16 no.2
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• pp.143-156
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• 2007

This study has researched the management status and the pollution level of water, soil, stream sediments of 11 abandoned coal mines out of a total of 12 within Obong-Dam area except Bukyung mine, which was submerged when constructing Obong-Dam, and selected areas which are in needs to have pollution control facilities in the first place. From the results of examination on the runoff at the waste rock pile and mineheads, the runoff from Sueun mine (pH, Fe, Al), Samwon mine (pH, Al), Wangdo mine (pH, Al), Mose mine (pH, Fe, Al) and Daeryeong mine (pH) exceeded the permissible discharge standards of the water quality, but the water at merging point with Obong-Dam after joined with Doma branch satisfied both Water Quality Standards and Drinking Water Quality Standards. In regard to groundwater contamination, it is found that areas where exceeded the Drinking Water Quality Standards are Wangdo mine (pH), Jangjae mine (pH, Zn), Daeryeong mine (pH) whereas all areas satisfied Soil Contamination Warning Standards of Soil Environmental Conservation Law. When comparing a research result on underwater sediments of branches of abandoned mines to the EPA Guidelines for classification of great lakes harbor sediments, Dongguk Gaerim (Fe), Jungwon mine (Fe), Daebo mine (Mn), Samwon mine (Mn) and Daeryeong mine (Mn) showed mid-level of contamination, whereas Sueun (Fe, Mn), Daebo mine (Fe), Woosung mine (Fe, Mn), Wangdo mine (Fe, Mn), Mose mine (Fe) and Daeryeong mine (Fe) showed high-level of contamination. In addition, contamination levels of underwater sediments in Wangsan and Doma branch where abandoned mine's branches merge together, Wangsan branch showed no contamination at all whereas Doma branch shows mid-level of contamination which reflect the Doma branch is affected by waste rock pile and minehead runoff of the abandoned mines in the Doma branch area. It is concluded that Mose mine and Sueun mine required treatment of acid mine drainage. and Wangdo, Jungwon, and Samwon mines were in need of mine tailing and erosion control work. The Samwon mine additionally required a control system for closed minehead runoff. Although the Samwon mine reached a high concentration of Al, Mn $Ca^{2+}$, $SO{_4}^{2-}$ in the runoff, the levels decreased after it was combined with a tributary. It has been concluded that after further monitoring of the cause of pollution, a preventive measure system may be needed to be built.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.291-300
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• 2013

The potential mineral resources in North Korea are magnesite, limestone, coal, graphite, iron, gold, silver, lead, and zinc. North Korea is mainly exporting coal and iron to China(70%) and EU countries. Gold ore reserves(or resources) in North Korea are about 2,000 tons and annual production is 2 tons based on metal. Major gold mines are Sooan, Holdong, and Daeyoodong mines and six smelters are operating. Fe ore reserves (or resources) are 4.3 billion tons and annual production is about 5 million tons based on 63.5% Fe. Major iron mines are Moosan, Leewon, Eunryul, Shinwon, and Jaeryong and 7 smelters are operating. Pb and Zn ore reserves(or resources) are Pb 470,000 tons and Zn 15 million tons, and annual productions are about Pb 26,000 tons and Zn 50,000 tons based on metal respectively. Major Pb-Zn mines are Gumdock and Seongcheon mines. Magnesite ore reserves(or resources) are 2.8 billion tons (95% MgO) and annual production is about 150,000 tons. Major magnesite mines are Ryongyang, Daeheung Youth and Ssangryong mines, and 5 magnesium refractory factories are operating. Apatite ore reserves(or resources) are 340 million tons(30% $P_2O_5$) and annual production is about 300,000 tons(crude ore). Major apatite mines are Daedaeri, Dongam and Poongnyen mines. Coal is established as an important strategic fuel mineral resources and is a major energy source in North Korea. Coal ore reserves(or resources) are 18.6 billion tons and annual production is about 20 million tons. The main coal fields is located in southern Pyongan and the Jigdong mine is the biggest in North Korea.

• Explosives and Blasting
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• v.42 no.2
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• pp.29-41
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• 2024

The increasing demand for metallic minerals due to global growth and the continued exploitation of near-surface minerals requires safe and efficient ways to mine ores present in deep mines. In deep mines, stresses concentrated around the cavity increase, which can lead to problems such as induced seismicity and rockbursts. In addition, the transfer of energy from blasting to deeply located faults can cause fault slip, which can lead to earthquakes, and controlling these events is key to deep mining methods. In this technical report, we will introduce the Underhand Closed Bench (UCB) mining method, which can control possible accidents and increase productivity when mining in deep mines.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.183-193
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• 2006

Several metalliferous and coal mines, including Seojin and Okdong located at the Kangwon province, were abandoned or closed since 1989 due to the mining industry promotion policy and thus disposed an enormous amount of mining wastes without a proper treatment facilities, resulting in water and soil pollution in the downstream areas. However, no quantitative assessment was made on soil and water pollution by the transport of mining wastes such as acid mine drainage, mine tailing, and rocky waste. In this research, total and fractional concentrations of heavy metals in mining wastes were analyzed and accordingly the degree of water and soil pollutions in the stream area were quantitatively assessed employing the several pollution indices. Concentrations of Ni, Cd, and Pb in soils near the abandoned coal mine areas were 1,240.0, 25.0 and 1,093.0 mg/kg, respectively, and these concentrations were higher than those in soils near the closed metalliferous mine areas. Also Cu concentrations in soils near the tailing dams were about 1967 mg/kg, which is considered as very polluted level. Results demonstrated that soil at the abandoned mine areas were highly contaminated by AMO, tailing, and effluents of the mining wastes. Therefore, a prompt countermeasure on the mining waste treatment and remediation of the codntaminated water and soil should be made to the abandoned or closed metalliferous and coal mines located at the abandoned mine area.

• Economic and Environmental Geology
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• v.31 no.6
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• pp.499-508
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• 1998

The Imgok Creek is located in the Gangreung coal field, which has been known that sulfides are more abundant than other coal fields in Korea, and it has been severly contaminated by acid mine drainage (AMD) discharging from the abandoned coal mines, such as the Youngdong, the Dongduk and the Waryong coal mines. The purposes of this study are to synthetically assess the contamination of natural water, stream sediment and cultivated soils, and to provide the basic data for AMD treatment. Geochemical samples were collected in December, 1996 (dry season) and April, 1997 (after three day's rainfall). TDS of the Youngdong mine water was remarkably higher than those of other mine waters. In the Imgok Creek, concentrations of most elements, except Fe decreased with distance by dilution caused by the inflow of uncontaminated tributaries. From the results of NAMDI and $I_{geo}$ calculation, the Youngdong coal mine was the main contamination source of the study area. Groundwater pollution was not yet confirmed in this study and the paddy and farm land soils were also not yet contaminated by mining activity based on the pollution index ranging from 0.27 to 0.47.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.6
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• pp.670-674
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• 2005

The respiratory quinone profile was used as a tool for the study on microbial community structure in the mine tailings of abandoned mines over the depth. For the study, the area of Jingok mine located in Bongwha, Korea has been selected. The distributions of Cd, Cu, Pb, Al, Fe and Mn showed the following common patterns; the highest values in the upper part of mine failings (0-20 cm), rapid decrease with increasing depth. The dominant quinone species of the mine tailings were UQ-9 followed by UQ-10, suggesting that microbes had contributed to heavy metal degradation. The quinone contents in mine tailings ranged from 5.0 to 24.9 nmol/kg. The microbial diversity in the upper part of mine tailings (0-40 cm) was higher than that of lower part of mine tailings (100-120 cm).

• Journal of Soil and Groundwater Environment
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• v.10 no.5
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• pp.25-36
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• 2005

Several metalliferous and coal mines, including Myungjin, Seojin and Okdong located at the upper watershed of Okdong stream, were abandoned or closed since 1988 due to the mining industry promotion policy. Thus these disposed an enormous amount of mining wastes without a proper treatment facilities, resulting in water pollution in the downstream areas. Acid mine drainage (AMD) and waste water effluents from the closed coal mines were very strongly acidic showing pH ranges of 2.7 to 4.5 and had a high level of Total Dissolved Solids (TDS) showing the ranges of 1,030 to 1,947 mg/L. Also heavy metal concentrations in these samples such as Fe, Cu, Cd and anion such as sulfate were very high. Concentrations of water soluble heavy metals in the Okdong streams were in the orders of Fe>Al>Mn>Zn>Cu>Pb>Cd, indicating Fe from the AMD and waste water effluents contributed greatly to the quality of water and soil in the lower watershed of Okdong stream. Copper concentrations in the effluents from the tile drainage of mine tailings dams were highest during the raining season. Water Pollution Index (WPI) of the surface water at the upper stream of Okdong river where AMD of the abandoned coal mines was flowed into main stream were in the ranges of 16.3 to 47.1. On the other hand, those at the mid stream where effluents from tailings dams and coal mines flowed into main stream were in the WPI ranges of 10.6 to 19.5. However, those at the lower stream were ranged from 10.6 to 14.9. These results indicated that mining wastes such as AMD and effluents from the closed mines were the major source to water pollution at the Okdong stream areas.