• Proceedings of the KSRS Conference
• /
• 2004.10a
• /
• pp.549-552
• /
• 2004

Since open-cut mining excavates gradually from the top of the mountain, vegetation planting is needed to reduce negative environmental impact on the surrounding environment. Accordingly, this study aimed at performing the environmental monitoring of the open-cut mining ground using the satellite remote sensing technique. As the research technique, in order to grasp the environmental change around the open-cut mining ground, NDVI (normalized difference vegetation index) was calculated, and every year change of the vegetation activity was analyzed. The results of the study showed lower vegetation activity in the open-cut mining ground compared to the surrounding areas and suggested the need for closed monitoring by remote sensing techniques.

• Explosives and Blasting
• /
• v.24 no.2
• /
• pp.75-82
• /
• 2006

Most of limestone mines in Korea have been developed by a open-cut mining method in consideration of a deposited condition of ore, ore recovery, safety, economic efficiency, etc.. But it has produced environmental problems such as dust flying, blasting noise & vibration, and spoil of farmlands due to slope failure of waste rock mass caused by access road construction, fragmentation & crush of rocks, blasting, transportation, and mineral processing. In this study, it has been suggested for measures to reduce mine hazards caused by open- cut mining of limestone nines.

• Tunnel and Underground Space
• /
• v.10 no.1
• /
• pp.80-91
• /
• 2000

Open cut mining of limestone is generally considered to be more advantageous than underground mining in recovery, grade control, economics, and safety, but it causes substantial environmental pollutants such as ground vibration, noise, dust. It also changes ground surface and may destroy vegetation. The Halla limestone mine which lies adjacent to Baikdu mountains range is selected for a model study. To reduce environmental hazards, and to conserve original surface and woods, both open cut and underground mining methods must be adopted. In case of sub-level sloping. a unit block of 87m high, 70m wide, and 100∼l20m long is suggested with an estimated overall recovery of 42%. Some suggestions to reduce the environmental hazards are also included. The followings must be considered in determining the degree of fragmentation; the discontinuity conditions in the rock mass and the charge concentration both at the bottom and column of the hole. In addition to adopting a barrier wall for reducing environmental hazards, the probable production from underground mining is also discussed.

• Explosives and Blasting
• /
• v.29 no.2
• /
• pp.13-31
• /
• 2011

Air deck charge blast methods have been applied to improve the fragmentation in open cut bench blastings for mining developments. However, during large scale bench blasting operations, there exist some problems such as boulder productions due to explosive charge concentration. Especially, in case of lime stone mining, when air deck method is applied, there has been unintentionally concentrated on charging because the inside holes are often broken by erosion and decomposition. In this study, compared with general blasting, air deck blasting has been focused in lime stone mining. In other to maximize its efficiency, inside hole was examined by endoscope in advance and deck charge using air tube was applied to the section in which concentration might be taken place. Blasting efficiency, fragmentation, charging reduction rate, and total working hours (from charging to blasting) were the main object for comparing, and as a result, air deck was more efficient then the general blasting in all aspects except total working hours.

• Geomechanics and Engineering
• /
• v.28 no.3
• /
• pp.299-311
• /
• 2022

Water-resisting key stratum (WKS) between coal seams is an important barrier that prevents water inrush from goaf in roof under multi-seam mining. The occurrence of water inrush can be evaluated effectively by analyzing the fracture of WKS in multi-seam mining. A "long beam" water inrush mechanical model was established using the multi-seam mining of No. 2+3 and No. 8 coal seams in Xiqu Mine as the research basis. The model comprehensively considers the pressure from goaf, the gravity of overburden rock, the gravity of accumulated water, and the constraint conditions. The stress distribution expression of the WKS was obtained under different mining distances in No. 8 coal seam. The criterion of breakage at any point of the WKS was obtained by introducing linear Mohr strength theory. By using the mechanical model, the fracture of the WKS in Xiqu Mine was examined and its breaking position was calculated. And the risk of water inrush was also evaluated. Moreover, breaking process of the WKS was reproduced with Flac3D numerical software, and was analyzed with on-site microseismic monitoring data. The results showed that when the coal face of No. 8 coal seam in Xiqu Mine advances to about 80 m ~ 100 m, the WKS is stretched and broken at the position of 60 m ~ 70 m away from the open-off cut, increasing the risk of water inrush from goaf in roof. This finding matched the result of microseismic analysis, confirming the reliability of the water inrush mechanical model. This study therefore provides a theoretical basis for the prevention of water inrush from goaf in roof in Xiqu Mine. It also provides a method for evaluating and monitoring water inrush from goaf in roof.

• The Korean Journal of Applied Statistics
• /
• v.33 no.3
• /
• pp.321-334
• /
• 2020

The US Federal Reserve (Fed) has decided to cut interest rates. When we look at the expression of the FOMC statements at the time of policy change period we can understand that Fed has been communicating with markets through a change of word selection. However, there is a criticism that the method of analyzing the expression of the decision sentence through the context can be subjective and limited in qualitative analysis. In this paper, we evaluate the signaling effect of FOMC statements based on previous research. We analyze decision making characteristics from the viewpoint of text mining and try to predict future policy trend changes by capturing changes in expressions between statements. For this purpose, a decision tree and neural network models are used. As a result of the analysis, it can be judged that the discrepancy indicators between statements could be used to predict the policy change in the future and that the US Federal Reserve has systematically implemented policy signaling through the policy statements.