Thank you very much, @chris .
I checked the reference of EPW and confirmed radiation values are not for the hour indicated.
But it may be mistake to use the sun position of 11:30 at 11:00.
This is in conflict with this reference:
Field: Direct Normal Radiation
This is the Direct Normal Radiation in Wh/m2. (Amount of solar radiation in Wh/m2 received directly from the solar disk on a surface perpendicular to the sun’s rays, during the number of minutes preceding the time indicated.) If the field is “missing ( 9999)” or invalid (<0), it is set to 0. Counts of such missing values are totaled and presented at the end of the runperiod.
Ladybug looks like using a sun position that is 30 minutes ahead of the displayed time.
But, shouldn’t it use the time 30 minutes before? (10:30 for 11:00)