Papers by Author: Byung Il Kim

Abstract: Impact behaviors of Aluminum Honeycombs Sandwich Panel (AHSP) by drop weight test were investigated in this study. Two types of specimens with l/2" and l/4" cell size were tested by two impactors with the weight of 5.25kgf and 11.9kgf respectively. Transient, contact and elastic-plastic analyses were performed by finite element method. Impact behavior of AHSP about impact sites appeared nearly the same in low impact energy, but it was different in high impact energy. Face was the strongest about impact and short-edge was the weakest. The damaged area of AHSP was enlarged with the increase of impactor weight that is corresponding to impact energy. After 3-point bending test, fracture modes of AHSP were analyzed with AE counts, lower face sheet was fractured in the long-edge direction first, and then separation between face sheet and core happened. In the short-edge direction after core wrinkled, lower face sheet was torn, impact behavior by FE analysis were increased localized damage in high velocity because the faster velocity of the impact was, the smaller the stress of core was. Consequently, impactor weight had an effect on widely damaged area, while the impact velocity gave rise to localized damaged area.

Abstract: The crystal structure, surface morphology and preferred orientation of copper electro-deposit were investigated by using sulfate bath with SiO2 suspension and the cathode substrate Au-sputtered. By addition of colloidal silica in copper electrolytic bath and Au pre-coating on substrate, the grains of deposits became fined and uniform and the number of grains were increased. Hardness of copper electrodeposits with colloidal silica increased about 15% in comparison with that of pure copper deposit film. The (111), (200) and (311) planes in the X-ray diffraction patterns were almost swept away, so preferred orientation of copper deposits change from (111) to (110) plane by co-deposit SiO2 and pre-coating the substrate.