Hi,
This all depends on your ASE. What is your ASE default charset? Get the output of sp_helpsort.
If your ASE default charset isn't some type that can hold Korean double byte characters the ASE will save them as ??? and if you look at the binary you will usually see A0 in the beginning. For other tools to see the characters correctly you need to specify the client character in the connection string.
If your ASE charset is a utf8 default then the other tool you are using to see them has a different default character set so you need for the other client to specify a client charset to view them correctly in isql you would add -Jutf8 in the connection string.
Thanks,
Dawn