When Han-geul was first invented, it was named 'Hoon
Min Jung Um(훈민정음)' by King Sejong. It means "The
true sound(letters) to be used to teach people".
However, the noble people at that time did not welcome the
advent of Han-geul, and since they were imbued with the view
that China is the center of the world, they kept an attitude
of despising Han-geul compared to Chinese characters and writings.
Therefore, Chinese characters and writings were called 'Jinseo(진서)-meaning
true letters' whereas Han-geul was often called 'Unmun(언문)'
And there are some views that Han-geul was called
'Amkul(암클)' because it was mainly used by
women, or 'Ahatkul(아했글)' because it was only for the use of
children who did not learned Chinese characters. However,
we cannot confirm whether the names were actually used because
there is no clear record of use of the names 'Amkul' or 'Ahatkul'.
During the civilization period, names like 'Jung Um(정음)',
'Gook Mun(국문)' were often used due to the high valuation
of Han-geul, letters native to Korea, as people began to cherish
national spirit. Joo Shi Kyung seems to be the first who named
Korean letters 'Han-geul'. Joo Shi Kyung devoted himself to
educating and studying Korean language and letters with great
affection for them. He began to use terms such as 'Han Nara
Gul(한나라글), Han Nara Mal(한나라말), Han Mal(한말)', and he changed
the names of 'Bae Dal Mal Gul Mot Um(배달말글 몯음)' or 'Chosun
O Kangsup Won(조선어 강습원)' to 'Han-geul Mo(한글모)', 'Han-geul Bae
Got(한글배곧)', and he also wrote 'Han-geul Pul Iee(한글풀이)' for
the children's magazine 'Aidle Boy(아이들보이)'(1913. 9) The name
'Han-geul' was generalized since then.