• Explosives and Blasting
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• v.21 no.2
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• pp.31-42
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• 2003

본 연구는 일반건설현장에서와는 달리 천공경이 $97mm{\Phi}$이상이고 천공장이 21M이상인 상태에서 발파작업이 진행되고 있는 석회석 광산에서 기존의 발파공법과 Air tubes를 이용한 발파공법을 비교하여 기존의 발파로 인한 상부 대괴를 감소시키고 폭약의 사용량을 줄이면서 진동 및 폭음을 최소화하여 보다 경제적인 작업수행을 하기 위해 연구하였다. 한편 에어층(Air deck)을 형성으로 인한 전색장의 길이 감소를 보완하기 위해 라바플러그(Rubber Plug)를 사용하므로 비석의 위험을 최소화 시키고 가스압이 암전체에 충분히 전달할 수 있도록 장치를 만들어 실험하였다. 그 결과 일반발파와 Air tubes를 이용한 발파방법을 비교하여 볼 때 Air tubes를 이용한 발파방법이 폭약을 약 15~30% 절감 할 수 있었으며, 또한 진동은 최대 50%정도의 감소와 폭음에서는 2~5dB 정도로 감소되었다.

• Clinical and Experimental Pediatrics
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• v.46 no.1
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• pp.37-41
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• 2003

Purpose : Although air enema reduction has been known as a good method of diagnosis and treatment of intussusception, it could develop colon perforation. However, there have been few studies about this complication. So we analyzed the risk factors of colon perforation during air enema reduction in patients with intussusception. Methods : We reviewed the charts of 12 colon perforation patients during air enema reduction of intussusception, who were admitted to Gil Medical Center from Jan. 1990 to Dec. 2001. Their age, sex, major symptoms, length of time till hospital visit, types of intussusception, operative findings and pathologic reports were reviewed. Results : Among 657 cases, 596 patients(90.7%) were successfully treated, but 12 patients(1.83%) failed in air enema reduction and had colon perforation. In patients with colon perforation the male to female ratio was 11 : 1, and average age was 5.3 months. The most common symptom at the time of hospital visit was vomiting(91.7%). Cyclic irritability(75.0%), bloody stool(75.0%) and abdominal mass(41.7%) were also noted. The average length of time between symptom onset and hospital visit was 44.7 hours. Types of intussusception were predominantly ileocolic, ileocecal, and ileoileocolic. The site of perforation was most commonly found at the proximal part of intussusception including ascending colon(50%) and transverse colon(50%). Most cases were uncomplicated, and had a single perforation. Pathologic reports showed hemorrhagic necrosis and mesenteric laceration at the site of colon perforation. Complications of colon perforation were tension pneumoperitonium(58.3%), requiring immediate decompression. Conclusion : The chance of colon perforation during air enema reduction increases in cases with small bowel obstruction on simple abdominal x-ray of a patient younger than 6 months, delay in time till hospital visit and higher air pressure during reduction. Therefore more careful investigation is needed in these cases.

• Explosives and Blasting
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• v.22 no.3
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• pp.57-64
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• 2004

There are two major types of underwater blasting at Korea, bridges and harbor construction work. Pier blasting for lay the foundation bridges construction is used dry excavation working (drilling and charging) after pump out water and then fire pump in water that is same as bench blasting. In contrast, underwater blasting for harbor construction and increase of harbor load depth is used to barge with digging equipment that is in oder to drilling on the surface and blasting work(charge, hook-up) under water. Thus, there are need to special concern such as charge method and hook-up method different from tunnel blasting work and bench blasting work. If do not use special concern breaks out dead pressure and mis fire because of there are so many difficult condition such as water pressure, obstruct field of vision. In this study underwater blasting at Busan Harbor Construction have consider with special concern that is plastic pipe charge method used to MegaMITE I and specialized buoy hook- up method make far initial system detonate on the surface used to TLD. The results is designed blast pattern charge per delay effect an inspection of verify between predict velocity and measure velocity. minimized break out mis fire consideration charge method, hook up method. According to result best underwater blasting design is 105mm drilling dia, MeGAMITE II, HiNLL Plus(non electric detonator).

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1996.03a
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• pp.95-106
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• 1996

건물발파해체 설계 및 시공에 있어서 중요한 공정의 하나는 불안정성을 유도하도록 실시하는 건물의 주요 지지부 기둥에 대한 발파이다. 이와 관련된 요소기술로는 기둥단면에 따라 천공패턴을 결정하고 적정장약량을 산정하는 것과 폭파시 파괴된 파편의 비산에 대한 방호기술을 들 수 있다. 비산은 인접건물에 대한 피해와 인명사고들을 유발할 수 있으므로 사전에 철저한 대책이 강구되어야 할 대상이다. (중략)

• Explosives and Blasting
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• v.31 no.2
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• pp.14-24
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• 2013

The most effective way of the rock removing works in the downtown area is to removing rocks by splitting the rock by blasting with small amount of explosives in the hole. However environmental factors not only limit the applications but also increase the forbidden area. As this is a distributed multi-stage blasting method and to reduce vibration by applying the optimized precisioncontrol-blasting method, it is applicable in all situations. The process is to fix the stemming-help plastic sheet to the hole entrance when stemming explosives and insert detonator and explosive primer with same delay time, two or three sets. This method is more efficient in the downtown area where claims and dispute from vibration are expected. This method is easily usable by designing blast pattern even in the area where delay time blasting is difficult after multi-stage explosive stemming due to short length of blast hole (1.2~3.0m) and there is no detonator wire shortage or dead-pressure.

• Journal of the Korean Geotechnical Society
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• v.25 no.7
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• pp.5-10
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• 2009

The ground anchor is not usually used in soft clay and loose sand, because the pullout resistance of anchors can not be guaranteed. However, there is a method to increase the capacity of anchors using electric discharge geotechnical technologies, which are also known as pulse discharge and electric-spark technologies. The pulse-discharge anchor has a bulbed (or underreamed) bond length that is expanded by high voltage electrokinetic pulse energy. 24 anchors were installed in the weathered soil and sandy clay at the Geotechnical Experimentation Site at Sungkyunkwan University in Suwon, Korea. In this study, in order to define a relation between expansion rate of the anchor diameter and ultimate load, anchor load tests were carried out in accordance with testing procedures by AASHTO (AASHTO 1990) and FHWA (Weatheb 1998). And then several anchors were exhumed to measure the diameter of the pulse discharge anchors.

• Explosives and Blasting
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• v.22 no.1
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• pp.15-22
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• 2004

일반적으로 석회석 광산에서의 발파는 ANFO를 사용하여 주로 시행되어지고 있다. Bulk장전 시스템의 도입으로 장약, 발파가 간편하여 효과적으로 발파를 할 수 있고 그 비용도 저렴하다는 장점을 가지고 있다. 그러나 수공에서의 장약이 불가능하고 낮은 위력으로 인해 저항선 및 공간격의 제한이 커서 이에 따르는 발파효율의 저하가 불가피 하였다. 본 연구는 현재 해외에서 일반화되어 사용되고 있는 Bulk EMX(HiMEX)폭약을 국내 현장에 적용함으로 그 적용 방법과 이점을 규명하고자 시행되었다. 대규모 석회석 광산을 대상으로 적정 패턴을 산출하기 위해 기존의 발파 패턴과 비교하여 시험발파를 시행하여 저항선 및 공간격을 산정 하였으며 이를 토대로 해서 성신양회, 현대시멘트 영월사업소와 함께 장기간 시험발파를 실시하고 그 자료를 검증하였다. 그 결과 HiMEX는 초유폭약에 비해 비중이 높아 공당 장약량은 45%정도 증가하나, 1발파 당 생산 물량이 증가하여 5%이상의 장약량 감소효과를 볼 수 있었다. 또한 35∼50%정도의 천공비용이 감소되는 것으로 나타났다.

• Explosives and Blasting
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• v.39 no.3
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• pp.15-23
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• 2021

Ventilation shafts are pathways in mines and tunnels for the removal of dust or smoke during underground space construction and operation. In mines, blasting with long blast holes is preferred for the excavation of a ventilation shaft in the 10~20m long crown pillar section. In this case, the bottom part of the blast hole is completely drilled in order to determine the drilling error, and this causes a problem of lowering the explosive charge and blasting efficiency. It is possible to solve the problem of explosive loading and to increase the blast efficiency by covering the curb of the blasthole by using stemming material. In this study, simulations for the blasting of a ventilation shaft were performed with various stemming lengths and the blasthole diameters(45, 76mm) using AUTODYN 2D SPH(Smooth particle hydrodynamics) analysis technique. Also the optimal bottom stemming column was derived by checking the size of the boulder and burden line according to blasting. Analysis result, blasting efficiency is lessened in case of stemming length less than 30cm and the optimal length of the stemming material should be 30cm or higher to achieve high efficiency of blasting.

• Explosives and Blasting
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• v.32 no.2
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• pp.1-8
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• 2014

In this study, 16 test blastings had been carried out with different spacings, burdens, drilling lengths, and charges per delay for investigating the characteristics of ground vibration propagation, which depends on the delay time. From the tests, it was possible to derive a ground vibration equation. Using the equation, the characteristics of ground vibration could be investigated by analyzing the nomogram and predicting the Peak Particle Velocity (PPV), which are influenced by the delay time and the priming location. The trend of ground vibration change depending on the delay time was analyzed for the standards charges of 0.5, 1.6, 5, and 15 kg, which were suggested in "Blasting design and construction guidelines to road construction" by the Ministry of Land, Infrastructure and Transport. From the study, it would be possible to suggest a favorable vibration control method, which depends on the charge.

• Tunnel and Underground Space
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• v.24 no.1
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• pp.97-109
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• 2014

In order to identify the characteristics of the propagation depending on delay time (20, 25 ms) and priming location (top priming, middle priming, bottom priming), test blasts were carried out a total of 4 times using different spacing, burden, drilling length, charge per delay and was derived the formula to predict blast vibration. This study investigated the characteristics of vibration by analysis of the nomogram and prediction of Peak Particle Velocity (PPV) from delay time and priming location by the formula to predict ground vibration. And it analyzed the trends of vibration increase by standards charge 0.5, 1.6, 5, 15 kg. Standards charge is "Blasting design and construction guidelines to road construction" by the Ministry of Land, Infrastructure and Transport. Depending on the charge in favor of vibration control method is proposed. Thus, when the design was to be used as a variable.