• Tunnel and Underground Space
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• v.22 no.2
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• pp.157-161
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• 2012

ZnO-98% and $Ga_2O_3$-2% powder were consolidated by shock compaction technique, which uses a high performance explosive. The microstructural and electrical characteristics of $ZnOGa_2O_3$ compact with density of 97% and hardness of 220~250 $H_v$ were investigated using SEM (Scanning Electron Microscope) and X-ray diffraction analysis, respectively. In the microstructures of the compact, there were no visible cracks at most of the surface areas, and interparticle bonding between powder particles was confirmed. The broadened peaks were detected due to deformation of crystallited size and high electric resistances were confirmed due to increased grains because of shock energy with a high pressure and high velocity.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.370-372
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• 2003

As there expands the usage of Al-Cu connections to interface aluminum and copper in power distribution systems, efforts to mitigate the mechanical, electrical or electro-chemical degradation are widely spreading. The explosive bending technology, in particular, has been thought as a countermeasure for the degradation. In this paper, electrochemical analysis and optical microscopic observation are carried out in order to compare the corrosion resistivities of the commercial compression type bimetallic sleeve and the explosion type bimetallic sleeve. The results show that the explosive bonding technology can prevent the interfacial corrosion caused by the formation of crevices and pits as well as from galvanic potential difference.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.208-211
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• 2007

Separation Devices have two functions. These two functions are to bond and to separate two bodies. This paper is about separation devices which use explosives to separate their bodies. Explosive bolt is separated with two bodies when the explosives in the body detonated. The good things of explosive bolt are that it has simple operational system and it is made of few parts. But it has side effects; fragment and pyre-shock. To avoid these side effects gas expansion separation(GES) bolt and pressure cartridge actuation separation(PAS) devices are invented. These use pressure to separate their bodies. The pressure is generated when explosives are burned. But the sizes of PAS devices are bigger than explosive bolts. And GES bolt has a mechanically lower bonding ability than that of explosive bolt. When you design separation devices, it is recommended to know operational system and characteristics of separation devices, to design best one.

• Journal of the Korea Institute of Building Construction
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• v.12 no.4
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• pp.442-450
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• 2012

In this study, fire resistance and residual strength were examined after the addition of PF fiber and bonding fireproofing gypsum board to a high strength concrete-model column of 50 MPa grade. At the beginning of the experiment, all the properties of base concrete appeared to satisfy the target range. In terms of the internal temperature record, a trend of slightly high temperature was shown when the fireproofing gypsum board was not bonding, and when the fireproofing gypsum board was bonding, as PF content increased gradually, the temperature was gradually lowered. In terms of the relationship, as time elapsed a low temperature was shown when fiber was mixed, and when the board was bonding, the trend of lower temperature could be confirmed. Meanwhile, in terms of spalling property, a severe explosive fracture was generated at PF 0%, and falling off was prevented as the fiber content was increased; however, discoloration and a multitude of cracks were discovered, and when the board was bonding, the trend in which the exterior became satisfactory when the content was increased emerged. In terms of the residual compressive strength, measuring of strength could not be performed at PF 0% without bonding of board, and the strength was increased as the fiber content was increased; however, there was a decrease in strength of about 30 ~ 40%, and in the case of PF 0% with the bonding of board, the strength could be measured; however, about an 80% decrease in strength was shown, and only about a 10 ~ 20% decline in strength was displayed, as the range of decrease was reduced as the fiber content was increased. Considering all of these factors, it was determined that a more efficient enhancement of fire resistance was obtained when two methods are applied in combination rather than when the PF fiber content and bonding of fireproofing gypsum board are utilized individually.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.2
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• pp.148-155
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• 2003

Japanese low activation terrific steel(JLF) is a good material for the parts of heat exchanger such as blanket and diverter. At first, JLF was developed as a candidate for structural materials in nuclear fusion applications. However, the development of the jointing technique of JLF steel to other materials is important for wide applications of this material to the industry fields. Recently the jointing technologies including diffusion bonding, brazing, roll bonding, explosive bonding and hot iso-static pressing have been studied for the heterogeneous materials of JLF-1 steel(Fe-9Cr-2W-V-Ta) and stainless steel(STS304). Friction welding is one of the most popular welding methods for two different kinds of materials. In this paper, the JLF-1 steel was jointed to SIS304 by friction welding method and the optimal conditions of the friction welding discussed. Acoustic emission was used as a nondestructive technique to evaluate the weld quality in processing.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.5
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• pp.219-223
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• 2014

Pulsed laser ablation in liquid medium was successfully employed to synthesize hydroxyapatite colloidal nanoparticles. The crystalline phase, particle morphology, size distribution and microstructure of the hydroxyapatite nanoparticles were investigated in detail. The obtained hydroxyapatite nanoparticles had spherical shape with sizes ranging from 5 to 20 nm. The laser ablation and the nanoparticle forming process were discussed with explosive ejection mechanism by investigating change of surface morphology on target. The analytical results of XPS, FT-IR and Raman spectroscopy confirms that the stoichiometry and bonding properties of the hydroxyapatite nanoparticles are in good agreement with reported bulk hydroxyapatite materials.