  A quantum group analysis is applied to the Sine-Gordon model (or may be its
version) in a strong-coupling regime. Infinitely many bound states are found
together with the corresponding S-matrices. These new solutions of the
Yang-Baxter eqations are related to some reducible representations of the
quantum $sl(2)$ algebra resembling the Kac-Moody algebra representations in the
Wess-Zumino-Witten-Novikov conformal field theory.
