Thanks for the hint.
I'm a little confused by the notice board that stated "pork bone is boiled at the highest heat for 20 hours..." .
I thought that boiling point stays the same temperature at the same atmospheric pressure. Also, that ramen broth is simmered at the lowest temperature for 20 hours?
Still, what do I know? I'm not a physicist nor Japanese and not a cook. 
Regards,
MTF
nt
