• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.67-75
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• 2016

In this paper, a pressure-time history curve of blast load and Conwep model are presented, and a simplified blast load formula is suggested. Generally, a blast load are applied as a pressure-time history curve, and it is calculated by blast load formula such as Conwep model. The Conwep model which is used in most of the blast analysis is quiet difficult to calculate because of its complex process. Therefore, a simplified formula is proposed to calculate blast load by simple rational expressions and to make a simplified pressure-time history curve. In this process, a curve fitting method was used to find the simple rational expressions. The calculation results of the simplified formula have an error of less than 1% in comparison with the Conwep model. And, blast analyses using finite elements method are accomplished with the Conwep model and simplified formula for verification.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.227-235
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• 2018

In this study, we developed a relational formula for observing high - resolution rainfall using vehicle rain sensor. The vehicle rain sensor consists of eight channels. Each channel generates a sensor signal by detecting the amount of rainfall on the windshield of the vehicle when rainfall occurs. The higher the rainfall, the lower the sensor signal is. Using these characteristics of the sensor signal generated by the rain sensor, we developed a relational expression. In order to generate specific rainfall, an artificial rainfall generator was constructed and the change of the sensor signal according to the variation of the rainfall amount in the artificial rainfall generator was analyzed. Among them, the optimal sensor channel which reflects various rainfall amounts through the sensitivity analysis was selected. The sensor signal was generated in 5 minutes using the selected channel and the representative values of the generated 5 - minute sensor signals were set as the average, 25th, 50th, and 75th quartiles. The calculated rainfall values were applied to the actual rainfall data using the constructed relational equation and the calculated rainfall amount was compared with the rainfall values observed at the rainfall station. Although the reliability of the relational expression was somewhat lower than that of the data of the verification result data, it was judged that the experimental data of the residual range was insufficient. The rainfall value was calculated by applying the developed relation to the actual rainfall, and compared with the rainfall value generated by the ground rainfall observation instrument observed at the same time to verify the reliability. As a result, the rain sensor showed a fine rainfall of less than 0.5 mm And the average observation error was 0.36mm.

• Tunnel and Underground Space
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• v.17 no.6
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• pp.484-492
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• 2007

The blasting vibration prediction in the country is mainly carried out by using the scaled distance method. But, this method needs a real-scale test blasting. The blasting vibration prediction has been performed using the data measured at borehole blasting for the purpose of a geological investigation before beginning a construction of a tunnel. In this prediction method, it is difficult to reflect the propagation characteristics of ground vibration generated from a real-scale blasting. propagation. This paper presents a new method for estimating blasting vibration by using superposed data of single hole blasting waveform with a delay time.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.10a
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• pp.510-512
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• 2008

• Journal of Korea Water Resources Association
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• v.42 no.10
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• pp.867-876
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• 2009

In this study, the stage-discharge relation curve made in 2006 is selected with standard curves to seize the hydraulic and geometric characteristics for the temporal variation of the river bed. The relationships among the standard stage-discharge relation curve and the existing stage-discharge relation curves, water level, cross sectional area, and flow velocity are analyzed. Jeokpogyo and Jindong which are the key station of Nakdong river are chosen for the study, with respect to the current river bed to convert the existing stage-discharge curves. The relationships for conversion of previous data, between water level and flow velocity are got. Also the relation equation between water level and cross sectional area and water level, flow velocity are derived. These conversion relationships shows good agreement between observed values and estimated values. It will be very useful to convert past hydraulic quantitations to current one.

• Tunnel and Underground Space
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• v.18 no.6
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• pp.418-426
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• 2008

A surface blasting method with a single tree face is currently used in Pasir Coal Mine in Indonesia. The single free face 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 this regard, we decided to make a specific blasting guideline for the control of found vibrations to ensure the safety of the pit slopes and waste dumps of the mine. Firstly, we derived a prediction equation for the ground vibration levels that could be occurred during blasting in the pits. Then, we set the allowable levels of ground vibrations for the pit slopes and waste dumps as peak particle velocities of 120mm/s and 60mm/s, respectively. From the prediction equation and allowable levels, safe scaled distances were established for field use. The blast design equations for the pit slopes and waste dumps were $D_s{\geq}5\;and\;D_S{\geq}10$ respectively. We also provide several standard blasting patterns for the hole depths of $3.3{sim}8.8m$.

• Geotechnical Engineering
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• v.11 no.3
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• pp.55-68
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• 1995

This paper is the analysis of the relationship between RQD and decay constant, blasting vi bration constant of cube root scaling and square root scaling, through experimental blast ins test in subway construction for excavation of shaft hole by bottom blasting. The magnitude of particle velocity is largely effected by the distance from blasting source, the maximum charge per delay and the properties of ground. In order to verify the effects of ground properties on blast-induced vibration, the relation-ship between magnitude of blasting vibration and Rock Quality Disignation which stands for joint property was studied. The results of test are verified that blasting vibration constant "K" and the absolute value("n") of decay constant relatively increse as RQD increased. According to the result, it can be predict the particle velocity by the blast -induced vibration in bottom blasting pattern.om blasting pattern.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.731-738
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• 2001

The conventional techniques for the prediction of natural frequency are often used to estimate the floor vibration. However. the predicted frequency differs significantly from the measured one since the predicted equation is not able to proper1y treat various material type. Transformation of slab section is necessary to predict natural frequency of composite deck plate, and this effort is complicated due to the various shape of each deck plate. In this study, a new simplified methodology to transform slab section is proposed, which treats effective depth as the distance from the top of a concrete topping to neutral axis of each deck plate. Finally proposed equation with fairly reasonable result compared to the measured values is obtained. based on the modification of vibration equation from LRFD theory. This efforts enhance errors in predicting frequency up to 15％.

• Journal of Radiation Protection and Research
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• v.22 no.1
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• pp.47-58
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• 1997

The conversion coefficients of effective dose per unit air kerma and equivalent dose per unit fluence were calculated by MCNP4A code for antero-posterior(AP) and postero- anterior(PA) incidence of broad, unidirectional beams of photons into anthropomorphic MIRD phantom. Calculations have been performed for 20 monoenergetic photons of energy ranging from 0.03 to 10 MeV. The conversion coefficients showed a good agreement with the corresponding values given in the draft publication of joint task group of ICRP and ICRU within 10%. The deviations may arise from the differences of geometry in the MIRD phantom and the ADAM/EVE phantoms, and the differences in the codes and cross-section data used. Inclusion of a specific oesophagus model results in effective dose slightly different(5% at most) from the effective doses obtained by adopting the equivalent doses for the thymus or pancreas. Deletion of the ULI from the remainder organ appeared not to be significant for the cases of photon dosimetry covered in this study.

• Explosives and Blasting
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• v.17 no.2
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• pp.36-44
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• 1999

A study was made on the design of the prediction model concerning blasting vibration in a constraction site, Namgu, Daegu City. The geology in this area consists of hornfels of shale and mud underlain by quartize, of which the main strike of the geological structure is NW direction. Measurements were carried out on the top of the wall concrete water storage tank, which is burried in the ground earth. The attenuation due to the vertical wall of the concrete structure may be experted because of spherical divergency at the bottom corner of the wall by the Huygens principle. For design of blasting prediction model, thus among scaled distance(SD) may be preferable to use in the regression model, since they represents most likely the average ground condition. Judging from the regression results, the cube root method may be more suitable for this area. The SD values for the maximum allowable vibration velocity of 0.5 cm/s, in this area are 22.5, 28.0 and 30.6 for the significance level of 50%, 95% and 99%, respectively.