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

• Steel and Composite Structures
• /
• v.27 no.3
• /
• pp.337-353
• /
• 2018

In previous weak-axis moment connection tests, brittle fracture always initiated near the edge of the beam flange groove weld due to force flow towards the stiffer column flanges, which is the opposite pattern as strong-axis moment connections. As part of the China NSFC (51278061) study, this paper tested two full-scale novel weak-axis reduced beam section moment connections, including one exterior frame connection specimen SJ-1 under beam end monotonic loading and one interior frame joint specimen SJ-2 under column top cyclic loading. Test results showed that these two specimens were able to satisfy the demands of FEMA-267 (1995) or ANSI/AISC 341-10 (2010) without experiencing brittle fracture. A parametric analysis using the finite element software ABAQUS was carried out to better understand the cyclic performance of the novel weak-axis reduced beam section moment connections, and the influence of the distance between skin plate and reduced beam section, a, the length of the reduced beam section, b, and the cutting depth of the reduced beam section, c, on the cyclic performance was analyzed. It was found that increasing three parametric values reasonably is beneficial to forming beam plastic hinges, and increasing the parameter a is conducive to reducing stress concentration of beam flange groove welds while increasing the parameters b and c can only reduce the peak stress of beam flange groove welds. The rules recommended by FEMA350 (2000) are suitable for designing the proposed weak-axis RBS moment connection, and a proven calculation formulation is given to determine the thickness of skin plate, the key components in the proposed weak-axis connections. Based on the experimental and numerical results, a design procedure for the proposed weak-axis RBS moment connections was developed.

• Journal of the Korean Society for Advanced Composite Structures
• /
• v.3 no.4
• /
• pp.27-37
• /
• 2012

The construction of a moment connection for a rectangular hollow section (RHS) column and a H-shaped beam is difficult because the RHS is a closed section. When a inner diaphragm is used for such a connection, in general, it is installed after cutting the HSS columns, which results in increased construction work. This paper suggests a new fabrication method to overcome such problems: An inner diaphragm is welded to inside a C-shaped section first, and then a column is fabricated by welding two C-shaped sections. This fabrication method is superior to a classic method in terms of constructibility. An experimental and a numerical study using Ansys 9.0 were performed in order to compare the strength of connections with respect to the presence of concrete, the corner shape of diaphragm, and the axis of loading. The experimental results including initial stiffness and ultimate loads are reported and the analytical results including load transfer mechanism, degree of stress concentration, and strain distribution are also reported.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.51-51
• /
• 2011

We have grown nanocrystalline graphite on sapphire substrate by using solid carbon source molecular beam epitaxy. Changes of structure from amorphous carbon to nanocrystalline graphite controlled by the growth temperature have been investigated by Raman spectroscopy. Raman spectra show D, G, and 2D peaks, whose intensities vary on the growth temperature. Atomic force microscopy reveals that the surface is very flat. Sapphire substrates of different cutting direction produce similar results. Simulations suggest that the interaction between carbon and oxygen causes disorders. Electrical transport measurements exhibit a Dirac-like peak, including a carrier type change by an external gate voltage bias.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2006.10a
• /
• pp.125-134
• /
• 2006

Process & mechanism $\blacklozenge$ The process consists from two steps which are laser processing step and separation steop. $\blacklozenge$ The wavelength of laser beam is transmissible wavelength for the wafer. However, inside of Si wafer is processed due to temperature dependence of optical absorption coefficient Advantage & Application $\blacklozenge$ Advantages are high speed dicing, no debris contaminants, completely dry process, etc. $\blacklozenge$ The cutting edges were fine, The lifetime and endurances did not degrade the device characteristics $\blacklozenge$ A separation of a wafer with DAF was introduced as an application for SiP

• Journal of Korean Society of Steel Construction
• /
• v.22 no.5
• /
• pp.477-485
• /
• 2010

Various monitoring sensors are used to predict and detect structural damage. Smart sensors, such as glass-fiber sensors, PZT, and MEMS, among others, have replaced traditional sensors. They are now being used in many areas. This study aims to predict the damage by measuring the PZT voltage attached on the specimen by the applied impact load. In the experiment to detect damages in beam connection, simple $H-400{\times}200{\times}8{\times}13$ beams were spliced with bolts. The results of FFT between PZT sensor and accelrometer were compared to measure the sensitivity of the PZT sensor. The damage to the beam was presumed by loosening the bolt, and then the damage measurement was accompanied. Secondly, a steel $PL600{\times}65{\times}5.8$ plate beam was fabricated for the purpose of experimenting on damage measurement. Impact loading test on three different locations was carried out. Damage width varied between 6~42mm on both sides by cutting, using a steel saw. The ratio of frequencies before and after the damage was computed to quantify the damage level by using FFT, and the change in mode pattern with the increased damage was investigated to measure the damage.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.766-777
• /
• 2008

Currently in increasing number of urban tunnels with small overburden are excavated according to the principle of the New Austrian Tunneling Method (NATM). Successful design, construction and maintenance of NATM tunnel demands prediction, control and monitoring of ground displacement and support stress high accuracy. A magnetic anisotropy sensor is used for nondestructive measurement of stress on surfaces of a ferromagnetic material, such as steel. The sensor is built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of a ferromagnetic material is measured in a nondestructive manner, which then can be translated into the absolute values of stresses existing on the surface of the material. This technique was applied to measure stresses of H-beams, used as tunnel support structures, to confirm expected measurement accuracy with reading error of about 10 to 20 MPa, which was confirmed by monitoring strains released during cutting tests The results show that this method could be one of the promising technologies for non-destructive stress measurement for safe construction and maintenance of underground rock structures encountered in civil and mining engineering.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.03a
• /
• pp.1392-1397
• /
• 2010

Currently in increasing number of urban tunnels with small overburden are excavated according to the principle of the New Austrian Tunneling Method(NATM). Successful design, construction and maintenance of NATM tunnel demands prediction, control and monitoring of ground displacement and support stress high accuracy. A magnetic anisotropy sensor is used for non-destructive measurement of stress on surfaces of a ferromagnetic material, such as steel. The sensor is built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of a ferromagnetic material is measured in a non-destructive manner, which then can be translated into the absolute values of stresses existing on the surface of the material. This technique was applied to measure stresses of H-beams, used as tunnel support structures, to confirm expected measurement accuracy with reading error of about 10 to 20MPa, which was confirmed by monitoring strains released during cutting tests The results show that this method could be one of the promising technologies for non-destructive stress measurement for safe construction and maintenance of underground rock structures encountered in civil and mining engineering.

• Journal of Animal Science and Technology
• /
• v.45 no.4
• /
• pp.577-584
• /
• 2003

Three dietary treatments were compared over two years to determine the effects of dietary protein levels and feeding patterns on velvet production in red deer (Cervus elaphus). The LL group received a 13% protein diet whereas the HH group received a 19% protein diet. The LH group switched from the low to high protein diet at the time of antler casting. Significant relationships were found between velvet production and the girth and length of main beam (p<0.01), daily growth rate of velvet (p<0.01), body weight at cutting time (p<0.05 in 1998 and p<0.01 in 1999), date of casting (p<0.01), and body weight and velvet production of the previous year (p<0.05 in 1998 and p<0.01 in 1999). Different levels of protein in diets in this study did not show statistically significant different effects in general. The girth of velvet, summed for top, middle and bottom of the main beam, tended to be thickest in HH for two years and thinnest in LL for 1998 and in LH for 1999. The main beam tended to be longest in HH at 46.3cm in 1998 and 45.2cm in 1999 and shortest in LH at 39.9cm in 1998 and 41.5cm in 1999. Velvet fresh weight tended to be highest in HH at 2,600$\pm$1,000g in 1998 and 3,038$\pm$867g in 1999 and lowest in LH at 2,287$\pm$826g in 1998 and 2,739$\pm$1,079g in 1999. Daily growth rate of velvet antler tended to be greatest in HH (43$\pm$16g/day in 1998 and 51$\pm$14g/day in 1999) and least in LH (38$\pm$15g/day in 1998 and 45$\pm$18g/day in 1999).