마부작침이 · 마부작침을
perseverance; grinding an axe into a needle
Example
마부작침의 자세로 꾸준히 연습하면 꼭 성공할 거예요.
If you practice steadily with an axe-to-needle attitude, you'll succeed.
Word parts
마 grind+부 axe+작 make+침 needle
Literally 'grind an axe to make a needle': patience achieves the impossible.