Dear Woojin Park, which radius you mean, either the radius of interaction or the radius of the solvent molecules ? My Regards

https://pymolwiki.org/index.php/Solvent_radius

https://doi.org/10.1021/j100696a037

https://www.researchgate.net/post/How-can-I-calculate-the-INTERACTION-RADIUS-R0-of-a-polymer-when-I-know-the-Hansen-solubility-parameters-dD-dP-and-dH-of-the-polymer

Dear Woojin Park . See the following useful link: https://pymolwiki.org/index.php/Solvent_radius#:~:text=The%20default%20solvent%20radius%20is%201.4%20Angstroms.

Kindly see also the following useful RG link: Article Solvated radius of ions in nonaqueous solvents

The radius of a solvated ion is not the solvent radius but a kind of ionic radius, of the SOLUTE, not of the solvent. Using the molecular volume of the solvent molecule, an approximate radius may be calculated. Obviously, this is only a rather rough approximation.

https://www.amazon.com/Organic-Solvents-Properties-Purification-Techniques/dp/0471084670

https://iopscience.iop.org/article/10.1088/1742-6596/1445/1/012025/meta

I wander if I live in a parallel world... Some answer are completely out of context...

Sorry for my bad mood.