hence ... 后面不需要加主语的!对吧?

hence ... 后面不需要加主语的!对吧?
e.g. I am interested in further study, hence my decision to join the graduate program.
这句话是完全正确的.hence后面不需要一个主语?
什么叫跟前面的主语一致？
那么下面这句话对吗？
It has always been my dream to pursue a PhD degree, hence my decision to apply for the graduate program.
嗯。谢谢！可是上面这句前面的主语是It，不是I，那hence还跟前面的主语一致吗？