• Explosives and Blasting
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• v.24 no.1
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• pp.57-62
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• 2006

The typical blasting method adopted in Pasir Coal Mine is a surface blasting technique with a single free face. It means that there is only one free face, which is usually the ground surface. This kind of blasting method is easy to use but inevitably causes enormous ground vibrations, which, in turn, can affect the stability of the slopes comprising the various boundaries of the open pit mine. In addition, the method also has the problem of lowering the blast efficiency compared to other methods such as bench blasting methods or ones with more than two free faces. In this respect, a project was launched to develop a new blasting method that is suitable for controling the ground vibration and enhancing the blast efficiency. As a part of the project, authors investigated the current blasting method as well as the overall pit developing process in the mine, and established some important guidelines that should be observed during the whole development process. This paper presents the details of the typical blasting pattern and the pit developing method in the mine, and suggests the guidelines determined from the results of the observations.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.3
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• pp.157-168
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• 2011

In order to promote efficiency of upstream and downstream migration of fishes, this study has developed a combined fishway of herring-bone bottom baffle type and brush type fishways. The results obtained are as follows : 1. In a channel with constant incline, the velocity of current generally shows a distinct tendency of acceleration as it goes down the stream. But in the hydraulic experiment of herring-bone bottom baffle type fishway, the velocity reached its maximum only at 0.4m/sec, and it tended to be stable without any acceleration. 2. The velocity in the brush type fishway showed a distinct tendency of acceleration as the discharge increased. But its greatest velocity was only 0.3m/sec, and its velocity change according to the discharge increase was only 0.15m/sec at maximum. 3. The maximum velocity in the combined type fishway was less than half of the blast speed of the poorest swimmer, the juvenile eel with 90mm of body length. So any species of fishes are supposed to be able to migrate upstream from the estuary through this combined type fishway. 4. The field experiment of upstream migration showed that the combined type fishway can promote efficiency of upstream and downstream migration of any species of fishes.

• Explosives and Blasting
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• v.30 no.1
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• pp.52-59
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• 2012

Fragmentation is one factor to affect productivity and economic efficiency of mine. Authors investigate the blasting pattern and improve it step by step while observing the fragmentation results. Final pattern was suggested and the fragmentation improved 24 % compared to traditional pattern, with 50 % is passing rate.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.469-472
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• 2006

Amount used of admixture fare is increasing for concrete economic efficiency and ability security. Security of economic efficiency and ability can expect by use of this admixture fare but is displaying a lot of problems on early age strength hold by hydrate delay relatively. Specially, in the case of construction site, concrete strength can speak that interrelation is high with mold removal of forms time. Therefore, is economical and need examination of plan that can secure robber within 3 days using admixture fare such as fly ash and blast furnace slage differential speech to secure function. In this study, adding liquid admixture within 1% of a binding agent quantity to examine these problem with physical characteristic after hardening ago specially, strength change at standard and air dry curing of observed change in priority. Air dried and water curing total strength enhancement effects appeared by thing which is in case of add test result liquid admixture by below 1% and strength deputy by passage of age could know is not big.

• Explosives and Blasting
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• v.24 no.2
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• pp.51-63
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• 2006

The typical blasting method adopted in Pasir Coal Mine is a surface blasting technique with a single free face. It means that there is only one free face, which is usually the ground surface. This kind of blasting method is easy to use but inevitably causes enormous ground vibrations, which, in turn, can affect the stability of the slopes comprising the various boundaries of the open pit mine. In addition, the method also has the problem of lowering the overall blast efficiency compared to other methods such as bench blasting methods or ones with more than two free faces. In this respect, a project was launched to develop a new blasting method that is suitable for both controling the ground vibration and enhancing the blast efficiency. As a part of the project, we investigated the current blasting method of the mine, and have conducted field measurements of the ground vibrations from 12 biasts. This Paper presents the details of the typical blasting pattern and the Propagation characteristics of the ground vibration from the surface blasting in the mine. Especially, various predictive equations for peak Particle velocities that can be used to estimate the ground vibration level in the mine area were derived from the regression analyses using the measured ground vibration data.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.692-705
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• 2018

Ground vibration is one of the remarkable issues in tunnel blasting. In recent studies, to improve the fragmentation with reduction of ground vibration in tunnel blasting, a vibration-controlled blasting method with artificial cutting slot near the center-cut holes has been suggested. This study examines the effect of the different arrangement of artificial cut-slot on the vibration reduction and fragmentation by performing the full-scaled concrete block blast experiments and the numerical simulations with 3D-DFPA. The results show that the existence of artificial slot contributes to the improvement of vibration reduction, blast fragmentation and the efficiency of the cutting slot blast. It can be explained that the artificial slot play a free surface role and should decrease the burden between the cut holes. Crater volumes of the blasted concrete blocks were measured by 3-dimensional digital image analysis and compared with the ideal standard crater volume which can be calculated by theoretical standard blast design method. As a result, the ratio of burden and hole diameter which should achieve the standard crater in the cut-hole blasting were suggested.

• Journal of the Korea Concrete Institute
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• v.27 no.5
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• pp.559-568
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• 2015

In this study, multi-component blended concrete mix with fly ash and ground granulated blast furnace slag according to 3 level of type of warter reduction agent (type of 0%, 8% and 16%) and 3 level of water-binder ratio (40%, 45% and 50%) was prepared for evaluation of effect of physical characteristics of concrete using multi-component blended binder according to warter reduction efficiency of warter reduction agent. In addition, concrete mix was carried out repetition test of three times in order to secure the reliability. As a result, compressive strength according to type of warter reduction agent was found that difference of strength was about 20% occurred, warter reduction efficiency of warter reduction agent was showed that a great influence on qualities of concrete. Therefore, reflected the effect of warter reduction efficiency of warter reduction agent, prediction model equations of compressive strength for multi-component blended concrete was proposed, it was found that more than 90% of the high correlation.

• Explosives and Blasting
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• v.29 no.2
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• pp.89-99
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• 2011

Recently on Jeju island there has been a lot of development and construction. However random distribution of porous basalt and clinker seam generated from volcanic activities often interrupt and greatly reduce efficiency of blasting necessary for construction. Three test blasts were operated to solve the inefficiency problem and results indicated that a powder factor of 0.40~0.45 $kg/cm^3$ is necessary to increase the efficiency of blasting. Also the blasting scheme should be concerned whether clinker seams exists in excavation levels or not.

• Explosives and Blasting
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• v.30 no.2
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• pp.66-76
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• 2012

Blasting technology aims to maximize digging efficiency as well as minimize vibration and noise. So, it is key point of blasting technology to raise blasting effect as much as possible and reduce vibration and noise and the design of PLHBM that is the tunnel blasting method having such merit was studied in this paper. PLHBM has the excellent blasting efficiency as it drills the empty hole with high caliber of 250~1,000mm at centre cut, contributes to blasting vibration reduction effect much and can be usefully applied to tunnel blasting sites. So it is judged that it enables the development of tunnel blasting method to be advanced one more step by studying and suggesting the design method of PLHBM.

• Tunnel and Underground Space
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• v.24 no.5
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• pp.386-394
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• 2014

Drilling accuracy is known to be one of the most important factors determining blasting efficiency in mining by blast operation. Therefore analysing the causes of drilling error and preparing a countermeasure for minimizing drilling error are very important for blasting efficiency and safety. In this study, causes of drilling error are analyzed with dividing them into controllable factors and uncontrollable factors, and relationship between each cause is also comprehended through field measurement and AHP analysis. Finally, effective measures to help lower the drilling error are proposed with the results from weighting analysis for each factor.