Hello, @김성찬 and All,
Here is a method, using regular expression syntax :
Open the Replace dialog ( Ctrl + F )
SEARCH ^\R|(\R)(?!\R)
REPLACE ?1\x20
Tick the Wrap around option, if necessary
Select the Regular expression search mode
Click on the Replace All button
Voila !
Notes :
The search regex tries to match, either :
True empty lines ( part ^\R ), which are deleted during replacement
EOL char(s), stored in group 1 ( as embedded in parentheses ) ONLY IF not followed with others EOL character(s) ( part (\R)(?!\R) )
In replacement, when group1 exists ( second alternative ) we replace the line-break with a space char
Best Regards
guy038