Given that \(x = \frac{y}{2}\), we can evaluate the expression \(\left(\frac{x^{3}}{y^{3}}+\frac{1}{2}\right) \div \left(\frac{1}{2} - \frac{x^{2}}{y^{2}}\right)\) as follows:

First, let's simplify the fractions inside the expression by substituting \(x = \frac{y}{2}\):

\begin{align}

\frac{x^{3}}{y^{3}} &= \frac{\left(\frac{y}{2}\right)^{3}}{y^{3}} = \frac{\frac{y^{3}}{8}}{y^{3}} = \frac{1}{8} \\

\frac{x^{2}}{y^{2}} &= \frac{\left(\frac{y}{2}\right)^{2}}{y^{2}} = \frac{\frac{y^{2}}{4}}{y^{2}} = \frac{1}{4}

\end{align}

Now, we can substitute these simplified fractions into the original expression:

\begin{align}

\left(\frac{x^{3}}{y^{3}}+\frac{1}{2}\right) \div \left(\frac{1}{2} - \frac{x^{2}}{y^{2}}\right) &= \left(\frac{1}{8} + \frac{1}{2}\right) \div \left(\frac{1}{2} - \frac{1}{4}\right) \\

&= \left(\frac{5}{8}\right) \div \left(\frac{1}{4}\right) \\

&= 5/8

\end{align}

So, the value of the expression is 5/8