  The medium modification of kaon and antikaon masses, compatible with low
energy KN scattering data, are studied in a chiral SU(3) model. The mutual
interactions with baryons in hot hadronic matter and the effects from the
baryonic Dirac sea on the K(${\rm {\bar K}}$) masses are examined. The
in-medium masses from the chiral SU(3) effective model are compared to those
from chiral perturbation theory. Furthermore, the influence of these in-medium
effects on kaon rapidity distributions and transverse energy spectra as well as
the $K, \bar{K}$ flow pattern in heavy-ion collision experiments at 1.5 to 2
A$\cdot$GeV are investigated within the HSD transport approach. Detailed
predictions on the transverse momentum and rapidity dependence of directed flow
$v_1$ and the elliptic flow $v_2$ are provided for Ni+Ni at 1.93 A$\cdot$GeV
within the various models, that can be used to determine the in-medium $K^\pm$
properties from the experimental side in the near future.
