Jang Yeong-sil

Hello! My name is Jang Yeong-sil. I was born in Korea during the Joseon Dynasty, a long, long time ago in the late 1300s. My family was not wealthy or powerful; in fact, we were part of the lowest social class, called the cheonmin. This meant that most people expected me to have a simple life without many opportunities. But I had a secret passion: I loved figuring out how things worked! I would spend hours watching water flow, observing the stars in the night sky, and thinking about how to build tools to make life easier for everyone. Even though my beginnings were humble, my mind was always buzzing with ideas.

My reputation as a clever problem-solver grew, and eventually, word of my skills reached the royal palace. In 1421, the great King Sejong heard about me. King Sejong was a wonderful ruler who believed that a person’s talent was more important than their social class. He invited me to work for him at the palace in the capital city, which was then called Hanseong and is now known as Seoul! It was the greatest honor of my life. In 1423, the King sent me on a special trip to China to study their advanced astronomical instruments. I learned so much and came back filled with exciting ideas for my own country.

With King Sejong’s support, I got to work creating amazing things. One of my proudest creations, completed in 1434, was the Jagyeokru, an incredible water clock. It didn't just tell time—it had little figures that would pop out and strike bells and gongs to announce the hour! That same year, I also designed a special sundial called the Angbuilgu, shaped like a bowl so that anyone, even people who couldn't read, could easily tell the time. Later, in 1441, I invented the world's first standardized rain gauge, the Cheugugi. This simple tool helped farmers know how much rain had fallen, which was very important for growing crops. I wanted my inventions to help all the people of Korea.

My time in the palace was full of discovery, but it didn't last forever. In 1442, an accident happened involving a royal carriage I had overseen, and I was sadly dismissed from my position. After that, the records of my life disappear, so no one knows what happened to me. But even though my personal story has a mysterious ending, my inventions lived on! The tools I created helped my country advance in science and technology for many years. Today, I am remembered as one of Korea’s greatest inventors, a person who rose from a humble background to change the world with curiosity and hard work. My story shows that it doesn't matter where you come from; what matters is the size of your ideas and the passion you have for making them real.