A Few Notes on Non-perturbative Parameters in Heavy Quark Expansion

Non-perturbative parameters to the order ${\cal O}({1 \over m_Q})$ in HQET expansion, $\bar{ \Lambda}$, $\lambda_1$ and $\lambda_2$, as well as the masses, $m_b$ and $m_c$, are estimated phenomenologically from $B$ and $D$ meson system spectroscopy. We found relatively large value of $m_b$ and quite small value of $\bar{ \Lambda}$ compared to previous estimates.