Shioda did not "take over" his fathers dojo. The original Yoshinkan Aikido dojo was financed by a business men and they placed Shioda in charge, hence the title of Kancho. The name Yoshinkan was the same name his father used for his kendo and judo school. The shin, as translated by the Yoshinkai Foundation is "spirit", or House to cultivate the spirit.
This is all documented at Aikido Journal/AikiNews as well as in the prologue of Total Aikido where Shioda Yasuhisa says "to cultivate mind and spirit" as the translation.