Text to the right of piecewise equation

Text to the right of piecewise equation

I have the following piecewise functions:
\begin{align*}
K(u) &= \begin{cases}
\frac{1}{2} & -1 \leq u \leq 1 \\
0 & \text{sonst}
\end{cases} \\ \\
K(u) &= \begin{cases}
\frac{3}{4}(1-u^{2}) & -1 \leq u \leq 1 \\
0 & \text{sonst}
\end{cases} \\ \\
K(u) &= \frac{1}{\sqrt{2\pi}}\text{exp}\left(-\frac{1}{2}u^{2} \right) \\ \\
K(u)&= \begin{cases}
\frac{3}{8}(3-5t^{2}) & -1 \leq u \leq 1 \\
0 & \text{sonst}
\end{cases}
\end{align*}
I would like to label each of these functions by placing text to the right
of them, in between the two cases. However, so far I've only managed to
put text on the same line as the cases.
Thanks!