  We have discovered errors in the calculation of some of the Einstein
coefficients in Table 5 and some plots in Figure 3. Due to the errors, the
square-root section of the curves of growth of Fe xxvi Ka and Kb, and Ni xxviii
Ka in Figure 3 were a few times underestimated. We correct Table 5 and re-plot
Figure 3 together with the unaffected curves. The program to calculate the
corrected curves of growth is available at
http://www.hp.phys.titech.ac.jp/kotani/cog/index.html
