Zhang Heng (78- 139) was born in Hirako. Han nationality, a native of Xi 'e, Nanyang (now Shiqiao, Nanyang City, Henan Province) [1], one of the five saints in Nanyang, and Sima Xiangru, Yang Xiong and Ban Gu are also called the four masters of Han Fu. China was a great astronomer, mathematician, inventor, geographer and writer in the Eastern Han Dynasty. He successively served as Langzhong, Taishiling, Shizhong and Hejian. In his later years, he became the minister of history of the DPRK due to illness. Yu Yonghe died in the fourth year (139) at the age of 62. In the Northern Song Dynasty, it was named Bo Er of Xi.

In astronomy, Zhang Heng has written Lingxian and Hunyi Illustration. In mathematics, there is a theory of calculation, and literary works are represented by Erjing Fu and Guitian. There is Zhang Hengji (14) in the capital city of Sui Shu, which has been lost for a long time. Zhang Qian, an Amin, compiled the Collection of Zhang He's Bamboo Slips, which was included in the Records of Han, Wei and Six Dynasties 130.

Zhang Heng made outstanding contributions to the development of astronomy, mechanical technology and seismology in China, and invented the armillary sphere and seismograph. He was one of the representatives of the theory of armillary sphere in the middle Eastern Han Dynasty. Later generations praised it as "Musheng" [2] (Kesheng). Because of his outstanding contribution, the United Nations Astronomical Organization named a crater on the back of the moon as "Zhangheng Crater" and the asteroid 1802 in the solar system as "Zhangheng Star". Later, in memory of Zhang Heng, Zhang Heng Museum was built in Nanyang.