  Fission fragment yield evaluations are one of the important nuclear data
studies. Fission accompanies various physical observables such as prompt
fission neutron, prompt fission gamma, and delayed-neutrons. When evaluating
fission fragment yields, a study including correlations among those observables
is essentially required. However, fission fragment yield data in the past JENDL
libraries have been made by focusing only on experimental fragment yields,
decay heats, and delayed neutron yields, and they have not been expanded into a
wider range of fission observables. This is because the evaluation method
adopted in the JENDL libraries could not study fission fragment yields and
particle emissions from fragments simultaneously. To solve this problem, a
calculation system with CCONE code is newly developed to estimate not only
independent and cumulative fission fragment yields but also prompt fission
neutron, prompt fission gamma, decay heats, and delayed-neutrons
simultaneously. This system enables us to study a correlation between various
fission observables. To determine lots of parameters in this system
efficiently, a Gaussian process and a least square fitting are adopted. We
tested the calculation system through a thermal neutron-induced fission on
$^{235}$U. In this paper, we demonstrate the performance of the parameter
search method and show that experimental fission fragment yield data and other
observables resulting from fission are reproduced well by the new calculation
system.
