• 한국분말재료학회지
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• 제10권6호
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• pp.430-435
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• 2003

The phenomenon of electrical explosion of conductors is considered in the context of the changes in the energy and structural states of the metal at the stages of energy delivery and relaxation of the primary products of EEC. It is shown that these changes are related to the forced interaction of an intense energy flux with matter and to the subsequent spontaneous relaxation processes. The characteristics of nano-sized metal powders are also discussed. The preferential gas media during EEC is Ar+$H_2$. An increase in $e/e_s$ (in the range of values studied) leads to a reduction in the metal content. For reactive powders obtained with high metal content, it is necessary to separate the SFAP fractions, which settled on the negative electrode of the electric filter.

• Structural Engineering and Mechanics
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• 제68권2호
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• pp.237-245
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• 2018

This study proposes an empirical formulation to predict the maximum deformation of offshore blast wall structure that is subjected to impact loading caused by hydrocarbon explosion. The blast wall model is assumed to be supported by a simply-supported boundary condition and corrugated panel is modelled. In total, 1,620 cases of LS-DYNA simulations were conducted to predict the maximum deformation of blast wall, and they were then used as input data for the development of the empirical formulation by regression analysis. Stainless steel was employed as materials and the strain rate effect was also taken into account. For the development of empirical formulation, a wide range of parametric studies were conducted by considering the main design parameters for corrugated panel, such as geometric properties (corrugation angle, breadth, height and thickness) and load profiles (peak pressure and time). In the case of the blast profile, idealised triangular shape is assumed. It is expected that the obtained empirical formulation will be useful for structural designers to predict maximum deformation of blast wall installed in offshore topside structures in the early design stage.

• 한국분말재료학회지
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• 제15권4호
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• pp.308-313
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• 2008

Al-Ni alloy nano powders have been produced by the electrical explosion of Ni-plated Al wire. The porous nano particles were prepared by leaching for Al-Ni alloy nano powders in 20wt% NaOH aqueous solution. The structural properties of leached porous nano powder were investigated by nitrogen physisorption, X-ray diffraction (XRD) and transmission Microscope (TEM). The surface areas of the leached powders were increased with amounts of AI in alloys. The pore size distributions of these powders were exhibited maxima at range of pore diameters 3.0 to 3.5 nm from the desorption isotherm. The maximum values of those were decreased with amounts of Al in alloys.

• 한국안전학회지
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• 제19권3호
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• pp.65-69
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• 2004

This study was performed with Hartmann type dust explosion apparatus and Godbert-Greenwald furnace apparatus in order to research the effect of temperature and humidity affecting LEL, minimum ignition temperature of Hydroxy Propyl Methyl Cellulose. The experimental determinations in the range between $20^{\circ}C\;and\;60^{\circ}C$ of temperature was not affected $LEL(180g/m^3)$ but LEL showed $200g/m^3\;and\;250g/m^3\;at\;80^{|circ}C\;and\;100^{\circ}C$. As the change of humidity LEL was $180g/m^3\;for\;50\%,\;200g/m^3\;for\;60\%\;and\;250g/m^3\;for\;70\%$ but dust explosion didn't occur over $80\%$. The ignition temperature of HPMC dust clouds was increased as increasing of humidity. So, the minimum ignition temperatures at $50\%,\;60\%,\;70\%\;80\%$ of humidity was $363^{\circ}C,\;375^{\circ}C,\;397^{\circ}C,\;405^{\circ}C$.

• Geomechanics and Engineering
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• 제17권3호
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• pp.295-305
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• 2019

The bedding plane has a significant influence on the effect of blasting fragmentation and the overall performance of underground mining. This paper explores the effects of fragmentation of the bedding plane and different angles by using the numerical analysis. ANSYS/LS-DYNA code was used for the implementation of the models. The models include a dynamic compressive and tensile failure which is applied to simulate the fractures generated by the explosion. Firstly, the cracks propagation with the non-bedding plane in the coal with two boreholes detonated simultaneously is calculated and the particle velocity and maximum principal stress at different points from the borehole are also discussed. Secondly, different delay times between the two boreholes are calculated to explore its effects on the propagation of the fractures. The results indicate that the coal around the right borehole is broken more fully and the range of the cracks propagation expanded with the delay time increases. The peak particle velocity decreases first and then increases with the distance from the right borehole increasing. Thirdly, different angles between the bedding plane and the centerline of the two boreholes and the transmission coefficient of stress wave at a bedding plane are considered. The results indicated that with the angles increase, the number of the fractures decreases while the transmission coefficient increases.

• Structural Engineering and Mechanics
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• 제87권3호
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• pp.273-282
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• 2023

Concrete construction, one of the oldest building practices, is commonly used in all parts of the world. Concrete is the primary building material for both residential and commercial constructions. The challenge of protecting the buildings, hence nation, against the attack of terrorism has raised the importance to explore the understanding of building materials against the explosion. In this research, a security check-post (reinforced concrete frame filled with plain cement concrete) has been chosen to study the behavior of structural elements under blast loading. Eight nitroglycerines-based dynamite blasts with varying amounts of explosive charge, up to 17 kg weight has been carried out at various scale distances. Pressure and acceleration time history records are measured using blast measuring instruments. Security check post after being exposed by explosive loading are photographed to view cracking/failure patterns on the structural elements. It is noted that with the increase of quantity of explosive, the dimensions of spalling and crack patterns increase on the front panels. Simple empirical analyses are conducted using ConWep and other design manuals such as UFC 3-340-02 (2008) and AASTP-1 (2010) for the purpose of comparison of blast parameters with the experimental records. The results of experimental workings are also compared with earlier researchers to check the compatibility of developed equations. It is believed that the current study presents the simple and preliminary procedure for calculating the air blast and ground shock parameters on the structures exposed to blast explosion.

• Korean Chemical Engineering Research
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• 제60권2호
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• pp.229-236
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• 2022

동일 분체특성의 분진이 평균입경, 농도, 분진조건(부유 또는 퇴적) 변화에 따른 화재폭발 위험성을 조사하였다. 이를 위해 20L분진폭발시험장치, 열중량분석장치, 연소속도시험장치(UN시험법)를 사용하였다. 4종 분진(Sugar, Mg, Al, Zr)의 입경이 서로 다른 8개 분진 시료에 대하여 부유 분진의 폭발특성과 화염전파속도(FPV), 그리고 퇴적분진의 화염확산속도(FSV)를 조사하였다. 부유 분진 조건에서 Mg 및 Al 분진은 입경이 감소하면 폭발 위험성이 증가하였지만, Sugar는 입경 변화에 따른 폭발 위험성의 영향이 거의 나타나지 않았다. 부유 분진의 화염전파속도(FPV)는 마이크로 범위에서의 입경 변화보다 마이크로에서 나노로 입경이 감소하면 크게 증가하였다. 퇴적층의 화염확산속도(FSV)는 수평면(기울기 0°)보다 경사면(기울기 30°)에서 증가하는 경향을 나타냈으며, 경사면(기울기 30°) 퇴적층 조건에서는 상방 전파가 하방 전파보다 높게 나타났다.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제2권2호
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• pp.123-133
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• 1998

As the results of investigation, the noise level was between 60 dB and 80 dB in the area of explosion. The residents living within 1 Km would feel uncomfortable. However, hearing loss is not happened by this range. The maximum range that the human can hear is 20,000 Hz and the maximum range that the dog can hear is between 20 Hz and 40,000 Hz. The auditory range for humans to be uncomfortable toward noise is between 1,000 Hz and 2,000 Hz. As the result of this experiment, the auditory range of dog is more wide than of a human. The change of hair cells in the Corti's organ occurred when the dog was exposed to 1,000 Hz at 100 dB for 1 month. Therefore, the structure change of the ear could happen by hearing loss because of noise, but the structure change of hair cells is the worst symptom by hearing loss because of noise.

• Nuclear Engineering and Technology
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• 제36권3호
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• pp.276-284
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• 2004

This paper presents the results of the TEXAS-V computer code simulations of FARO L-14, L-28, and L-33. The old break-up model and new break-up model are tested to compare the respective simulations of each. As these experimental data sets cover a wide range of ambient pressures, sub-cooling of the water pool, and the melt jet diameters, the results of the simulations will be beneficial in assessing the TEXAS-V code's capability to predict the steam explosion phenomena in a prototypical reactor case. The current model was found to have some deficiencies, and the modules for the fragmentation, the equation of state, and the interfacial area for each flow regime in TEXAS-V were improved for the simulation of FARO L28 and FARO L-33.

• 전기학회논문지
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• 제59권7호
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• pp.1272-1275
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• 2010

The Cu powder was prepared in distilled water. It has a wide range of size distribution. The submicron-sized particles in the Cu powder were removed by using continuous type centrifugal separator. The average particle size after classification was approximately 50nm. The XRD analysis showed that pure Cu phase and oxide phase ($Cu_2O$)weremixedinthepowderpreparedbythismethod.