We have studied electric dipole (E1) strength distribution in neutron and p
roton drip line nuclei Be-12(4)8, Be-14(4)10, and O-13(8)5 by large scale s
hell model calculations with the effect of loosely-bound single particle wa
ve functions. Large El strength is found in the low excitation energy regio
n below E-x=3 MeV in both Be-12(4)8 and O-13(8)5, while strong E1 strength
is found only in high excitation energy region above E-x=7 MeV in Be-14(4)1
0. The effect of extended wave functions and the coherence in the transitio
n amplitudes enhance significantly the E1 strength in the low energy region
. A manifestation of melting of the shell magicity at N = 8 and Z = 8 is po
inted out in the systematics of E1 transitions in Be and O isotopes.