抄録
We proposed the evaluation function of drinking ease, which contains the evaluation of appropriate amount and adjustability, in order to specify the dimension of opening diameter for drinking ease. The result of optimization has shown that the subjects may get the closest beverage amount to the appropriate amount when they drink from the 34.3 mm opening in case of green tea, and the 32.5 mm opening in case of carbonated beverage. We consider that the evaluation function of drinking ease possibly specifies the dimension of opening diameter on drinking ease.