Barbara Sim A-gi was born in Gwangju, Gyeonggi-do in 1783. She learned the catechism from her brother Sim Nak-hun, and became a Catholic. She performed her Christian duties faithfully as a Catholic. She was so moved by the stories of the Saints, that she made up her mind to dedicate herself to God, as a virgin. So she stayed at home and observed the teaching of the Church, faithfully.
  
  
   Since her brother was arrested in 1801 during the Shinyu Persecution, she expected that she would be arrested also. So she prepared her heart and soul and waited. When the police finally came to take her, she said to her mother, “Mother, don`t be so sad and let me obey the holy will of the Lord." She professed bravely her faith in God to the police. She changed her clothes without any fear, and was taken to Seoul.
  
  
   At the Police Headquarters, Barbara Sim was punished severely to force her to betray God. But she did not yield under any circumstances. Failing to endure the continuous torture she died a martyr in early April, 1801. Barbara Sim was 18 years old.
  
  
   Meanwhile, her brother, who had been arrested earlier, was sent into exile to Muan, Hamgyeong-do. When he heard that his sister Barbara was martyred by being beaten to death he said to the persecutors:
  
   "It is I who taught the catechism to my sister, Barbara. She died a martyr by being beaten to death by the police. She never denied her faith in God."