Jang's invention of the water clock saw its infusion throughout the country, however, these were very costly. Development of the sundial provided a cheaper and more manageable alternative. Jang, Ichun, Kimjo, and other scientists made Korea's first sundial, the "Angbu-ilgu" (앙부일구/), which meant "pot-shaped sun clock staring at the sky". "Angbu-ilgu" was bronze in composition, and consisted of a bowl marked with 13 meters to indicate time and 4 legs jointed by a cross at the base. Seven lines crossed the 13 meters in different curves to compensate for the seasonal changes of the course of the sun. "Angbu-ilgu" and other variants, such as the "Hyeonju Ilgu" (현주일구/) and the "Cheonpyeong Ilgu" (천평일구/), were implemented in strategic spots, such as the town's main streets with heavy traffic, so that the people could be well informed of the time. To compensate for the high illiteracy rate among the commoners, 12 shapes of the Chinese zodiac were engraved in juxtaposition with the meters. No sundials from the Joseon Dynasty made during King Sejong's reign still exist today; none are known to have survived past the Japanese invasions of Korea (1592–1598) (임진왜란).