SUNG practiced at Kim & Chang for 13 years since 2004, focusing on regulatory matters for financial institutions, mergers and acquisitions for financial institutions or domestic and foreign private equity funds, and public company-related matters such as tender offers and shareholder meetings. For about five years since 2017, he served as Head of Legal Department and Head of Policy Division at Hyundai Capital, Hyundai Card, and Hyundai Commercial, being responsible for tasks of inhouse counsels, external affairs, works related to information security, etc. With his experience as both a law firm and in-house counsel, he has the expertise and ability to understand the client's perspective.