When Doowon Koh came from Korea to work with me at the University of
Missouri, I immediately knew that he was an outstanding student. He
was willing to read very difficult papers and always came to meeting
prepared. What was wonderful and somewhat humorous was the contrast
between him and Derrick Hart. If I sent a calculation to Derrick
that was not correct, he would walk into my office and say something
like: "Alex! The calculation is wrong!". Doowon approached such
things very differently. He would usual say: "Professor Iosevich!
How should formula in line 5 on page 7 of your draft be
interprepeted?" What he mean was that line 5 was completely wrong.
My usual reaction was to ask him how he "interprets" that line.
Doowon would inevitably tell me that he "took the liberty of
rephrasing" line 5 and hand me a new draft where everything was
completely correct.
One of the most amazing moments of my interaction with Doowon was on
the day when he defended his thesis. This was the first time he
called me by my first name instead of "Professor Iosevich". Our
collaboration and friendship has continued to this day.