Spacetime Singularities in String and its Low Dimensional Effective
  Theory
  Spacetime singularities are studied in both the $D+d$-dimensional string
theory and its $D$-dimensional effective theory, obtained by the Kaluza-Klein
compactification. It is found that spacetime singularities in the low
dimensional effective theory may or may not remain after lifted to the
$D+d$-dimensional string theory, depending on particular solutions. It is also
found that there exist cases in which spacetime singularities appearing in
high/low dimensional spacetimes do not necessarily happen on the same surfaces.
