The integral wrt y is best tackled by using the power series for sine and substituting y3 for the argument:
sin(y3)=y3-(y3)3/3!+(y3)5/5!-...=n=1Σn=∞(-1)n-1y6n-3/(2n-1)!
On integration we get n=1Σn=∞(-1)n-1y6n-2/[(6n-2)(2n-1)!] to which we apply the limits.