Yun's death was announced by Mayor Steven Fulop Monday on Twitter.
"He was a great co worker and a tireless advocate for the people of #JerseyCity," Fulop said.
"More than that he was a great father, husband, and grandfather. I can speak for the entire JC community that we are devastated."
Yun was elected to the city council in 2013. His current term is set to expire in December 2021.
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