Values in test_coreloss.py Need to be Modified

[haoranli1031]

As the results of: 1) the units of f, B and P have been changed, and 2) the definition of duty ratios for trapezoidal wave has been changed, the assertion values in the test_coreloss.py need to be modified.

To avoid mistakes, @ds9056 let's double check the codes and define the new assertion values for future tests.