• Journal of the Korean Professional Engineers Association
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• v.23 no.6
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• pp.41-46
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• 1990

First of all, Under given condition such as bit gage of 36mm Drill bit with right class of jack-logs experimental test carried out from two face of Bench, firing of each hole brought 90 degree Angle face and them measured length of Burden and charged ammount of powder as following. (equation omitted) A=Activated Area A=ndi=m S=Peripheral length of Charged. room Ca=Rock Coeffiecency d : di=Hole diameter When constructed subway of Seoul in 1980 the blasting works increased complaint of ground vibration. in order to prevent the damage to structures. Some empirical equations were made as follows on condition with Jackleg Drill (Bit Gage ø 36mm) and within 30 meter distance between blasting site and structures. V=K(D / W)$\^$-n/ N=1.60-1.78 K=48-138 Project one of contineous works to above a determination of empirical equation on the cautious blasting vibration with Crawler Drill(ø 70-75mm) in long distance. V=41(equation omitted) V=124(equation omitted).

• Tunnel and Underground Space
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• v.16 no.5 s.64
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• pp.377-386
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• 2006

In generally blasting pattern design is carried out in-situ borehole blasting test and its analysis. We added the 3D numerical analysis for blast induced vibrations. This paper is case study of 3D numerical analysis in which considered blast induced vibration affected across buildings, and then we design the blasting pattern of tunnel excavation.

• Explosives and Blasting
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• v.23 no.2
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• pp.45-56
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• 2005

In this study, fracture formation and fracture volume by blasting demolition of model reinforced concrete pillars were compared with various vertical load and influence of reinforced steel bar. The more vertical load increased, the more tensile cracks and vertical direction cracks produced. In vertical load of 2.0ton, tensile cracks on vertical direction were predominantly produced. Generally, the more vertical load increased, the more bending deformation of concrete steel bar decreased. As a result, vertical load was influenced fracture formation of concrete and bending deformation of reinforced steel bar. Reinforced steel bar was influenced fracture volume of concrete. According to vertical load and influence of reinforce steel bar by blasting demolition of reinforced concrete pillars, drilling and blasting pattern may be modified.

• Explosives and Blasting
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• v.40 no.2
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• pp.25-34
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• 2022

Recently, there has been an increasing number of cases of improving constructability by using electronic detonators with precise delay time in tunnel blasting sites. This case is a case of conducting test blasting using with non-electric detonator and electronic detonator at the site of 『Seoul Metropolitan Area Express Railroad Route A Private Investment Project Section 00』 that requires careful management of vibration and noise. Although this site was designed with a non-electric detonator, it was attempted to improve the advance rate and control vibration and noise by mixing the non-electric detonator and the electronic detonator due to the decrease in the advance rate. As a result of the blasting, the target value was achieved with an advance rate of about 85% and a maximum measured value of vibration and noise is 0.215cm/sec and 73.22dB(A) which were measured below regulatory standards. As blasting works in downtown areas, it is necessary to designate measurement and management objects to continuously manage vibration and noise.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.891-901
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• 2016

By comparing test blasting data experimented in three layered-structure polymorphic grounds to a geological profile, influence of blast vibration with respect to uncontrollable ground characteristics was analyzed. Inefficient blast have been performed without sufficient verifications or confirmations because insufficiencies with regard to experiments and data of blasting engineering on the layered structures to be irregularly repeated clinker layer consisted of volcanic clastic zones. It is difficult to quantify N values of clinkers within test blasting region because they have diverse ranges, or coverages. An absolute value of attenuation coefficient N in a field, estimated by blasting vibration predictive equation (SRSD), are lesser than criteria of a design instruction, meaning that vibrations caused by blast can spread far away, and the vibrational characteristics of blasting test No.1, indicating relatively small values, inferred by the geological profile, pressures of gas by the explosion may be lost into a widely distributed clinker layers by penetrating holes resulted from blast into vicinity of clinker layers located in bottom of soft rock layers at the moment of blast. As a result, amounts of spalling rocks are decreased by almost half. Also, ranges of primary frequencies in the fields are identified as similar to those of natural frequency of typical structures.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.262-271
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• 2000

The purpose of this study was to estimate shear bond strength according to difference in Targis surface treatment and storage condition. 140 non-carious extracted human molars and Targis D210(Ivoclar, Liechtenstein) were used in the present study and were divided into 7 experimental groups respectively according to surface treatment of Targis. Group 1 ; No treatment, Group 2 ; $50{\mu}m$ aluminium oxide blasting, Group 3 ; 4% HF etching for 3 minutes, Group 4 ; 4% HF etching after blasting, Group 5 ; silane treatment after blasting, Group 6 ; silane treatment after 4% HF etching, Group 7 ; silane treatment after blasting and 4% HF etching. In Each group, one half of 20 specimens was stored in distilled water at $37^{\circ}C$ for 24 hours and the other half was stored at atmosphere for 24 hours respectively. Dentin surface was etched with 10% $H_3PO_4$ for 15 seconds and luting cement(Variolink II, Vivadent, Liechtenstein) was applied by manufacturer's recommendation. Shear bond strength for each group was then measured. To examine the failure patterns after shear bond test and to observe the change after surface treatment of Targis. Specimens were fabricated and observed under the SEM. Statistical analysis was performed by One Way ANOVA test and t-test. The results were as follows ; 1. The shear bond strength of the groups stored in water significantly lower than that of groups stored at atmosphere (P<0.05). 2. There was no significant difference in shear bond strength in groups stored in water (P>0.05). 3. The shear bond strength without surface treatment of Targis were lowest among all experimental groups in atmosphere condition(P<0.05). 4. There was no significant difference in bond strength between groups using the silane or not(P>0.05). 5. The groups treated by blasting, hydrofluoric acid and silane sequentially showed highest bond strength than that of other groups in atmosphere condition, but there was no significant difference(P>0.05). 6 The proportions of the specimens showing the mixed fracture failure were 20% in HF etching group and blasting + HF group, 40% in blasting + HF + silane group in atmosphere condition. All the specimens stored in water showed adhesive fracture failure.

• Corrosion Science and Technology
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• v.10 no.3
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• pp.80-86
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• 2011

Welding was widely used in shipbuilding industries as a joining method. In present study, the effects of welding fume contaminated on steel surface on corrosion protection were examined by water ballast simulation test and condensation chamber test. Pull-off adhesion test, blistering test and cathodic disbondment test were carried out to evaluate the effects of residual welding fume. Consequently, it was clearly indicated that the residual welding fume didn't affect the corrosion protection of epoxy coated on steel when surface was treated by light sweep blasting to heavy sweep blasting which was applied in this study.

• Journal of the Korean GEO-environmental Society
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• v.16 no.9
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• pp.23-32
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• 2015

This study examined blast testing measurement data which had been obtained from 97 field sites in Korea to investigate the comprehensive characteristics of rock blasting-induced vibration focusing on the effect of excavation types (tunnel, bench) and rock types. The measurement data was from the testing sites mostly in Kangwon province and Kyungsang province and rock types were granite, gneiss, limestone, sand stone, and shale in the order of number of data. The study indicated that the blasting-induced vibration velocity was affected by the excavation types (tunnel, bench) and bench blasting induced higher velocity than tunnel blasting. In addition, the vibration velocity was also highly affected by the rock types and therefore, it can be concluded that rock types should be considered in the future to estimate a blasting-induced vibration velocity. Furthermore, the pre-existing criteria was compared with the results of this study and the comparison indicated that there was a discernable difference except for tunnel blasting results based on the square root scaling and therefore, further studies and interests, which include the effects of rock strength, joint characteristics, geological formation, excavation type, power type, measurement equipment and method, might be necessarily in relation to the estimation of blasting-induced vibration velocity in rock mass.

• Explosives and Blasting
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• v.41 no.3
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• pp.26-37
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• 2023

In order to determine the amount of explosives that can minimize the vibration generated during tunnel construction using the blasting method, it is necessary to derive the blasting vibration coefficients, K and n, by analyzing the vibration records of trial blasting in the field or under similar conditions. In this study, we aimed to develop a technique that can derive reasonable K and n when trial blasting cannot be performed. To this end, we collected full-scale trial blast data and studied how to predict the blast vibration coefficient (K, n) according to the type of explosive, center cut blasting method, rock origin and type, and rock grade using deep learning (DL). In addition, the correction value between full-scale and borehole trial blasting results was calculated to compensate for the limitations of the borehole trial blasting results and to carry out a design that aligns more closely with reality. In this study, when comparing the available explosive amount according to the borehole trial blasting result equation, the predictions from deep learning (DL) exceed 50%, and the result with the correction value is similar to other blast vibration estimation equations or about 20% more, enabling more economical design.

• Explosives and Blasting
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• v.23 no.1
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• pp.31-39
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• 2005

This study is based on the reseach about conte. track$(Dugso\~wonju)$ double line electric railway tunnel. Authors conducted test blasting to examine the effect of blasting pollution. To be conducted safe and effective work by using this result studies sailable substitution excavation method. No-vibration section generates continuously the vibration of breaker working to go abreast necessarily secondary fragmentation working and according to judging that application is actually difficult in case of the condition of study site, the period of construction, the cost of construction, the efficiency of construction, pre-heavy caliber horizontally boring working + line drilling method + vibration control secondary blasting method excavation working is possible from level within blast vibration standard.