Sejung Lee Partner
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  • TEL 82 2 6003 7079
  • FAX 82 2 6003 7029
  • E-MAIL
Sejung Lee is a partner at Yoon & Yang LLC. Her main practice areas include intellectual property and antitrust and competition.
Ms. Lee advises clients in connection with intellectual property matters, including patent, trade secrets, industrial technology, copyrights, trademarks, design rights, unfair competition, and related litigation. Furthermore, she advises on antitrust and competition issues such as abuse of market dominance and unfair trade practices. In particular, she is experienced in antitrust regulations related to intellectual property.


  • 2007-present Yoon & Yang LLC
  • 2013-14 Finnegan LLP Reston, VA


  • 2013 Boston College Law School, LL.M.
  • 2011 Seoul National University, Graduate School of Law, LL.D.
  • 2007 Judicial Research and Training Institute
  • 2005 Seoul National University, Graduate School of Law, LL.M.
  • 2000 Seoul National University, College of Law, LL.B.

Representative Matters

  • Advised and represented SK Innovation in the United States and Korea in connection with trade secret and patent disputes with LG Chem concerning rechargeable batteries
  • Advised Qualcomm (a standard essential patent holder) on administrative litigation concerning the Korea Fair Trade Commission’s investigation into Qualcomm’s licensing practices and the chip industry
  • Advised shipping company in connection with repairs of defects in LNG carrier cargos and represented the shipping company in foreign arbitration in connection with investigations into alleged violation of the Industrial Technology Protection Act, advised on approvals and reporting of national key technology exports, and domestic litigation
  • Advised leading steel company on compliance and assessment of dispute risks relating to intellectual property
  • Advised SK Hynix in t trade secret infringement lawsuit relating to NAND flash memory filed in the US and Japan
  • Represented SK Innovation in the case seeking adjudication on patent infringement dispute regarding lithium ion rechargeable battery membranes
  • Advised domestic semiconductor company on overseas intellectual property dispute risks, including compliance issues such as preservation and management of documents
  • Advised and represented three major television networks in the case seeking prohibition of simultaneous retransmission of programs (copyrighted works) against major cable networks
  • Represented OTO Melara in domestic litigation as well as arbitration in Paris in connection with trade secret infringement relating to gunfire manufacturing technology
  • Represented and advised Korean and foreign film companies in seeking injunction against webs storage device operators for copyright infringement and compensation for damages
  • Represented an internet portal service company in connection with its liability for copyright infringement by its users
  • Represented a German company against allegations of patent infringement concerning automatic waste collection facilities
  • Represented a pharmaceutical company in Korea Fair Trade’s investigations into alleged unfair trade practices


  • Trade Mark Star, MIP IP Stars (2020-2022)
  • 40 Under 40, Asian Legal Business (ALB) (2016)


  • Korea Chapter, Trade Secrets, Chambers Global Practice Guides (Co-author, Chambers and Partners, 2020, 2021, 2022, 2023)
  • Korea Chapter, Copyright, Chambers Global Practice Guides (Co-author, Chambers and Partners, 2021, 2022, 2023)
  • Neutralization Of Technical Protection Measures, Law & Technology Vol. 5 No. 1, pp.153~pp.160 (Center for Technology and Law, Seoul National University, 2009)
  • A Study on the Principle of Change of Circumstances, LL.M. Thesis (Seoul National University, 2005)