• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.1
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• pp.9-20
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• 1985

Generally the stiffened plate in the ship structure is subjected to not only axial load but shear load. With respect to those combined loads buckling analysis in necessary. In this paper, buckling strength is analyzed by using Finite Element Method when the stiffened plate with hole is under loading conditions mentioned above. To obtain the higher buckling strength, we need some reinforcement. The methods of reinforcement are attaching doubler around hole and stiffeners in the arbitrary directions For the sake of convenience those arbitrary directions were selected paralleled($0^{\circ}C$), vertical($90^{\circ}C$)and oblique($45^{\circ}C$) to the edge. Two kinds of method mentioned above are investigated, it is clarified that which of the two is more effective reinforcement. From the viewpoint of buckling strength, following conclusions were obtained. When external load direction is unknown, doubler reinforcement is more effective than those of parallel and vertical stiffener. And oblique stiffener reinforcement is more effective than that of doubler when external load direction is know.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.4
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• pp.31-37
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• 2002

Recently a simplified design procedure as well as load transfer model for seismic steel moment connections with welded straight haunch have been proposed by Lee and Uang. Cyclic seismic testing was conducted to verify the proposed design procedure and to develop the details that will prevent the cracking at the haunch tip, where stress concentration was the highest. All the specimens thus designed effectively pushed plastic hinging away from the haunch tip and were able to develop satisfactory plastic rotation capacity of 0.04 radian with no fracture. A sloped edge combined with drilling a hole near the haunch tip or a pair of stiffeners(partially or fully) extended from the beam web successfully prevented the crack initiation at the haunch tip. The strut action of the haunch web, which had been predicted from the previous analytical study, was also experimentally identified through the strain gage readings.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.383-390
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• 2020

Wedge locks have been widely used for spaceborne electronics for mounting or removal of a printed circuit board (PCB) during integration, test and maintenance process. However, it can basically provide a mechanical constraint on the edge of the board. Thus, securing a fatigue life of solder joint for electronic package by limiting board deflection becomes difficult as the board size increases. Previously, additional stiffeners have been applied to reduce the board deflection, but the mass and volume increases of electronics are unavoidable. To overcome the aforementioned limitation, we proposed an application of multi-layered PCB sheet with viscoelastic adhesive tapes to implement high-damping capability on the board. Thus, it is more advantageous in securing the fatigue life of package under launch environment compared with the previous approach. The basic characteristics of the PCB with the multi-layered sheet was investigated through free-vibration tests at various temperatures. The effectiveness of the proposed design was validated through launch vibration test at qualification level and fatigue life prediction of electronic package based on the test results.