• 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.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.2
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• pp.145-151
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• 2017

As an alternative to conventional explosive methods for demolition of concrete structures and rocks, the use of non-explosive demolition agents can be considered to reduce noise, vibration, and dust emissions during the demolition process. In this study, we conduct finite element analysis for crack initiation and propagation caused by the expansion of non-explosive demolition agents in square concrete structures. The predicted crack patterns are compared with the experimental results in the literature. The minimum values of the required expansion pressure of non-explosive demolition agents are also estimated, which depend upon the arrangement of non-explosive demolition agents and empty holes. Furthermore, we investigate the effect of empty holes on the fragmentation of concrete structures, and discuss the effective arrangement of non-explosive demolition agents and empty holes for fragmentation improvement.

• Explosives and Blasting
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• v.28 no.1
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• pp.19-26
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• 2010

The paper presents a case study of a limestone quarry of the Philippines, where major problems in terms of improper fragmentation, poor wall control, and poor heave of the muck pile were witnessed. The paper highlights the significant role of switching over from diagonal firing pattern to V-type firing pattern, and also of making suitable adjustments in the stemming column length for improved confinement and gas retention. The study revealed that by making aforesaid design modifications in the blast round, marked improvement in blasting results was registered. Looking at the results, it was further contemplated to expand the mesh area in the subsequent blast rounds. The mesh area was incremented from the existing $8.96m^2$ to $12m^2$. The results were meticulously registered in the field, and clearly depicted definite improvements in the blast results in terms of increased P.F., reduced boulder count, reduced FEL cycle time, reduced dozing hours and improved heave.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.121-129
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• 2017

In this study, the quality of recycled aggregate for concrete was investigated as the number of recycled aggregate crushing cycles, grinder and crusher, peeling and crushing. First, the quality of density, absorption ratio and solid content was improved as the separation distance decreased and the number of crushing increased, depending on the number of crushing of recycled aggregate and the distance between mantle and cone cave. The quality of density, absorption ratio and solid content was improved as the wire mesh used in striking plate and the number of hammers increased, depending on the type of striking plate and the number of hammers.

• Explosives and Blasting
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• v.35 no.1
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• pp.18-26
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• 2017

In Analysis of Fragmentation of rock blasted, The photo analysis method has been mainly used and these image acquisitions are mainly obtained by digital image from the front of the crushed rock. However, Image analysis is basically advantage of the image of planar shooting not front shooting but There is no way to take a photograph of huge plane rock slope. Thus, Unavoidably It is resolved by distorting or extending the image filmed at the front as well as adjusting it similar to its angle of plane shooting. Lately, With advancing unmanned aerial vehicle, It can simply image the fragment conditions of blasted rock of a high-definition digital image and Through it, It can acquire the most planar image to angle which accumulate cataclastic rock and also can make image analysis. In this study, It has been confirmed that tolerance value of analysis result of image filmed flatly is markedly lower than the existing front filmed image.

• Explosives and Blasting
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• v.28 no.2
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• pp.28-36
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• 2010

A study about economical blasting methods which can improve fragmentation and save explosive in blasting is in progress. One of the blasting methods is an air decking method making air layers in boreholes. However, it is difficult to apply this method to the boreholes filled with water. In this study, an underwater Air Tube was manufactured and tried to place it at a certain location in a water filled borehole. It was found that the application of underwater air tube in wet boreholes could improve the fragmentation and save 10~15% of the explosives.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.325-331
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• 2010

In the present research paper large scale blasting was conducted on two different firing patterns, namely, straight V type and skewed V type pattern on the same sandstone overburden bench with similar explosives. The post-blast fragmentation assessments were made by use of digital imaging technique. The total cycle time of 10 $m^3$ rope shovels was also recorded in the field. The results reveal improvements in the fragmentation and excavator performance results for the blasts fired on skewed V type pattern. The paper discusses the skewed V firing pattern and the reasons for its superior performance vis-$\grave{a}$-vis the straight V type pattern.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.71-71
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• 2019

고사리(Ferns)는 고사리 속(Pteridium spp.)에 속하는 양치식물의 총칭으로서 우리나라에는 22과 70속 272종이 분포되어 있는 것으로 보고되었다. 고사리의 어린 순에는 가식부 100 g 당 칼슘 15.0mg, 칼륨 185.0mg 등이 함유되어 있으며 골다공증, 심혈관질환 등에 효과가 있고 식이섬유로 인해 변비 예방에도 유용한 것으로 알려져 있다. 고사리 뿌리에서 추출한 전분은 중국 및 일본 등지에서 면류나 제과용으로 이용되고 있어 고사리 재배의 부가가치를 향상시킬 수 있는 방안으로 기대되고 있다. 본 연구에서는 고사리 뿌리는 가정용믹서기로 분쇄하는 방법과 고무망치를 사용해 파쇄한 방법에서 식품첨가제로 이용되고 있는 sodium metabisulfite 등 3종의 산화방지제를 사용하여 추출한 전분의 이화학적 특성을 조사하였다. 고사리 전분의 추출 수율은 분쇄하는 방법에서 높은 경향이었고 추출용액 중에서는 sodium metabisulfite 4% 용액에서 분쇄 처리 9.5%와 파쇄 처리 8.3%로 가장 높은 수율을 보였고, ascorbic acid 침지에서는 5.1%와 5.5%로 낮은 수율을 나타냈다. 추출한 전분의 색도값에서는 파쇄하는 처리에서 L 값이 높아지고 a와 b 값은 낮아지는 경향이었고 sodium metabisulfite 4% 용액 침지에서 분쇄와 파쇄 두 방법에서 가장 높은 명도값을 보였다. 고사리 전분의 추출방법별 Ca 함량은 분쇄 처리에 파쇄 처리에서 높아지는 양상을 보였고 파쇄 후 ascorbic acid 4% 용액에서 추출하는 처리에서 0.23%로 가장 높았으며, Mg 함량도 분쇄 처리에 비해 파쇄 처리에서 경미하게 높은 양상을 보였다. 유효태 Fe 함량 또한 파쇄처리에서 높은 경향을 보였고 추출 용액중에서는 ascorbic acid 4% 용액이 0.12%의 높은 함량을 보였다. 고사리 전분의 추출방법별 호화특성에서 최고 점도는 증류수, ascorbic acid 및 sodium carbonate 추출에서는 파쇄하는 방법에서 높아지는 경향이었지만 sodium metabisulfite 추출에서는 감소하는 경향을 보였다. 강하점도는 모든 추출용액에서 분쇄 처리에 비해 파쇄 처리에서 현저하게 증가하는 양상을 보였고 치반점도는 sodium metabisulfite와 ascorbic acid 추출은 파쇄처리에서 83.9 RVU와 53.0RVU로 낮아지는 경향을 보인 반면 sodium carbonate와 증류수 추출에서는 증가하는 양상을 나타냈다. 호화시간은 분쇄 처리가 파쇄 처리에 비해 약간 늘어나는 경향이었고 추출용액 간에는 큰 차이가 없었으며 호화온도는 분쇄처리가 파쇄 처리에 비해 높아지는 결과를 나타냈으며 파쇄한 고사리 뿌리를 증류수를 이용해 추출한 전분에서 가장 낮은 $69.7^{\circ}C$의 호화온도를 보였다.

• Tunnel and Underground Space
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• v.24 no.6
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• pp.440-448
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• 2014

Hydraulic fracturing technique has been applied in various fields in order to improve the recovery of energy resources such as gas, oil and geothermal energy and research about finding out hydraulic fracturing mechanism and application has been steadily proceeded. In this study, for effective hydraulic fracturing, a scale modeling was progressed to simulate similarly with the actual site. In order to analyze the development aspect of surface crack initiation pressure during hydraulic fracturing followed by different conditions, the number of guide holes hydraulic fracturing test was carried out by setting up a hydraulic fracturing test equipment. Also, through the result, we tried to derive reliable results by comparing and analyzing the value of numerical modeling which is obtained based on the physical properties and mechanical properties with 3DEC, a three-dimensional discrete element method program. As a result, it is considered possible to generate effective crack using the guide hole.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.85-89
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• 2019

Cell-free protein synthesis utilizes the translational machinery in a cell extract. Unlike the conventional cell-based expression methods, not being affected by the conditions for cell growth, cell-free protein synthesis enables flexible manipulation of individual factors affecting the efficiency protein biosynthesis. However, the high cost and low stability of the energy sources to regenerate ATP have limited the use of cell-free synthesis for large-scale production of recombinant proteins. One of the approaches to address this problem is to use glucose as an alternative energy source to regenerate ATP through the glucose-metabolizing pathways in a cell extract. In this study, in an attempt to improve the efficiency of ATP regeneration by reinforcing oxidative phosphorylation process, we supplemented with cellular lipids to a glucose-fueled reaction mixture for cell-free protein synthesis. As a result of the lipid supplementation, the productivity of chloramphenicol acetyltransferase in a cell-free synthesis system using glucose increased more than 6 fold compared to when the lipid was not supplemented.