How did the emporer yangdi change china?

Yangdi extended this transportation system in 610, beginning the Grand Canal network that was later used to supply the capital and northern border armies with food from the south. He strengthened China’s northern border by rebuilding, at great expense, the Great Wall separating China from Inner Asia. Yangdi further strained his dwindling resources by spending lavish sums on palace construction and ornamentation, stocking his private park with mature trees carried on specially constructed carts from distant forests. Finally, he embarked on a series of foreign adventures, extending the Chinese empire south to present-day Vietnam and north into Inner Asia.

They made a checks and balance system to equal power within the branches. the "check" meant that one branch would watch one branch and "balance" them if they were too powerful. if you want more info on this, i would just google checks and balance system.