• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.229-235
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• 2010

In this study, fire resistance performance of high strength concrete specimen with fireproof gypsum board was investigated for possible use in upgrading fire-resistant performance of the existing building and repair of fire damaged structures. Fire test of eight identical high strength concrete columns were carried out for 180 minutes in accordance with ISO-834. The temperature distributions in longitudinal reinforcement and concrete temperature at various depths were recorded. The fireproof performance of gypsum board and explosive spalling of concrete were observed. The specimens with 15 mm thick twoply fireproof gypsum board spalled after gypsum board crumbled regardless of fastening methods. However, when the thickness of fireproof gypsum board was more than 30 mm, it was possible to prevent the explosive spalling and control the rebar temperature. Although the effect of cover thickness could not be compared because the explosive spalling occurred, there seemed to be no difference in insulation efficiency.

• Journal of the Semiconductor & Display Technology
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• v.17 no.1
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• pp.54-61
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• 2018

In this study, two aspects were analyzed about the robot for removal of explosive devices. First, the cost analyses were performed to provide a reasonable solution for the acquirement of the system. It is processed by an engineering estimate method and the process was consisted of two ways : a system development expense and a mass production unit price. In additions, the resultant cost analyses were compared between the cases excluding and including a mines detection system. As results, in the case of the acquirement of the robot system for removal of explosive devices, it is recommended that the performance by improving the mines detection ability should be considered preferentially rather than the cost because the material cost for the mines detection system is negligible compared to the whole system cost. Second, as a way for improving the system performance by the mine detection function, the carbon nanotube (CNT) based sensor technology was studied in terms of sensitivity and simple productivity with presenting its preliminary experimental results. The detection electrodes were formed by a photolithography method using a photosensitive CNT paste. As results, this method was shown as a scalable and expandable technology for the excellent mines detection sensors.

• Explosives and Blasting
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• v.36 no.2
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• pp.10-18
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• 2018

The shaped charge is used in explosive demolition of steel frame structure, but it was often not used because it was limited to use or impossible to supply at domestic and foreign. To solve this problem, we needed a device that could generate matal jets using industrial explosive. In this study, we made a charging container, which metal jets were generated when explosives were detonated. Cutting performance tests were carried out to evaluate the effect of cutting of a charging container on a steel plate of 25mm thickness. In addition, we compared the results between the numerical simulation of penetration process and cutting performance tests and then was evaluated a cutting performance for steel plates of 35mm and 70mm thickness.

• Explosives and Blasting
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• v.38 no.2
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• pp.13-21
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• 2020

The shaped charge was used in explosive demolition of a steel frame structure, but it was often not used because it was limited to use and impossible to supply at domestic and overseas. Existing linear shaped charge did not have sufficient cutting performance to cut steel frame structures with a huge scale and thick steel plate. To solve these problems, we produced a device that could generate metal jets using industrial explosives of high detonation velocity and pressure. In this study, we made a charging container of three types which applicable to explosive demolition of steel frame structures. The experiment of cutting performances was carried out to evaluate the effect of cutting of charging containers on the various thicknesses of the H-beam and steel plate. As a result of the experiment, sufficient cutting performance was confirmed.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.493-500
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• 2013

In this study, it was evaluated the protective performance of the protection material for filed of the army by impact of fragment from the explosion of 155mm artillery shell to propose the improvement items. And it was evaluated the protection materials for structural boby such as corrugated steel plate, concrete block, prevention paint of explosion, aluminum foam and concrete T-wall by impact of fragment of 155mm artillery shells and explosion-induced pressure of C-4 explosive. As a result, protective performance of the existing protective material was superior but reinforcement is necessary for secondary damage because sand is leaking. The protective performance of new protective materials was greater than existing protective materials. And it can be used for protective materials.

• Explosives and Blasting
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• v.25 no.1
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• pp.45-52
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• 2007

When emulsion explosives(1kg/cartridge) are loaded into a long vertical borehole at open blasting site, they undergo an Impact corresponding to 117.6J of shock energy. After shocking. the crystallization of emulsion nay happen immediately. Furthermore, it nay cause a desensitization, arising from increase in the density of emulsion explosive by the breakage of sensitizer. In this paper, some experimental work was performed using PVC pipe equipment(50mm diameter and 12m lengths) to investigate the effects of loading impart of emulsion explosive. It is shown that detonation energy decreases up to 26% of the normal state value and this effect is less than 3% of the total performance of emulsion explosives in borehole blasting.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.6
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• pp.322-330
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• 2020

This study deals with underwater explosion (UNDEX) characteristics of various non-explosive underwater shock sources for the development of non-explosive underwater shock testing devices. UNDEX can neutralize ships' structure and the equipment onboard causing serious damage to combat and survivability. The shock proof performance of naval ships has been for a long time studied through simulations, but full-scale Live Fire Test and Evaluation (LFT&E) using real explosives have been limited due to the high risk and cost. For this reason, many researches have been tried to develop full scale ship shock tests without using actual explosives. In this study, experiments were conducted to find the characteristics of the underwater shock waves from actual explosive and non-explosive shock sources such as the airbag inflators and Vaporizing Foil Actuator (VFA). In order to derive the empirical equation for the maximum pressure value of the underwater shock wave generated by the non-explosive impact source, repeated experiments were conducted according to the number and distance. In addition, a Shock Response Spectrum (SRS) technique, which is a frequency-based function, was used to compare the response of floating bodies generated by underwater shock waves from each explosion source. In order to compare the magnitude of the underwater shock waves generated by each explosion source, Keel Shock Factor (KSF), which is a measure for estimating the amount of shock experienced by a naval ship from an underwater explosionan, was used.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.3
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• pp.56-61
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• 2002

The hexanitrohexaazaisowurtzitane(HNIW) is a polycyclic caged nitramine oxidizer. For most existing weapons systems, the most critical ingredient in explosive and propellant applications is the oxidizer, HNIW, with its increase in performance output and energy capabilities for future in explosive and propellant systems. Two new polyacylhexaazaisowurtzitanes were synthesized. Pentaacetylhexaaza-isowurtzitane(PAIW) or pentaacetylformylhexaazaisowurtzitane(PAFIW) can be a precursor in the preparation of HNIW, recently developed highly energetic material.

• Laser Solutions
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• v.4 no.2
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• pp.39-45
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• 2001

This paper introduces a cleaning process for removing submicron-sized particles from NiP hard disk substrates by the liquid-assisted laser cleaning technique. Measurements of cleaning Performance and time-resolved optical diagnostics are Performed to analyze the physical mechanism of contaminant removal. The results reveal that nanosecond laser pulses are effective for removing the contaminants regardless of the wavelength and that a thermal mechanism involving explosive vaporization of liquid dominates the cleaning process.

• Journal of Biosystems Engineering
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• v.34 no.6
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• pp.404-410
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• 2009

This study was carried out to develop a self-propelled type explosive subsoiler for improving the root zone soil conditions in orchard and other forest fields. Prototype was designed to be able to inject air and other soil improving material such as lime into soil at the same time, and thus improve the air permeability and drainage of orchard soils to promote the root growth of tree for high quality fruit production. Soil penetration device of explosive subsoiler is composed of air hammer, penetration rob and air injection nozzle. To support the soil penetration device of explosive subsoiler to penetrate vertically, modified Scott-Russel mechanism was used. Timing control device for simultaneous injection of soil improving material with air was attached to the out side wall of air cylinder and as the cylinder move, the soil improving material was injected into soil at the same time. Turning radius of prototype was 2.2-2.3 m with good mobility in sloped land. It took approximately 1 minute for lime injection system to reach the optimum pressure of 9.9 kg/$cm^2$, average 10-20 seconds were required to rupture soil with the depth of 50 cm and 2-3 seconds were required for explosion, so all in all about 1 minute and 20 seconds were required for one cycle of explosion. Maximum soil rupture depth and diameter were 50 cm and 3-4 m respectively depending on the soil type and soil moisture content. For final design of explosive subsoiler inclination angle of lime hopper was increased from 60 degree to 70 degree and the shape of hopper was changed from rectangular cone to circular cone to solve the clogging problem of lime at out let. Agitating system operated by compressed air was attached to the metering device of the prototype, thus more than 90 cc of lime was discharged per cycle from metering device without clogging problems.