Chaho Jung has published an article titled Patent Damages Determination in Korea, 49 IIC 267-98 (2018). Here is the abstract:
This paper provides a comprehensive introduction to the jurisprudence of patent damages calculation in Korea. It compares Korean patent damages jurisprudence with corresponding foreign systems as far as possible. Further, this paper also summarizes unique and/or important Korean patent damages jurisprudence. Firstly, Sec. 128 of the Korea Patent Act provides three different calculation methods, lost profit, infringer’s profit and reasonable royalty, from which the plaintiff may freely choose any one method. Secondly, para. 2 of Sec. 128 permits the plaintiff to prove lost profit through the number of the infringer’s assigned products, without proving his own reduced sales. Thirdly, under para. 4, the infringer’s profit is presumed to be the plaintiff’s loss. This presumption can be rebutted by the defendant by proving, for example, limited manufacturing capacity of the plaintiff. Therefore, the Korean infringer’s profit method is not effective for the plaintiff whose manufacturing capacity is limited. Fourthly, under para. 5, the plaintiff may request a reasonable royalty, which could have been agreed upon through a hypothetical agreement. The Korean reasonable royalty jurisprudence is not much different from, for example, that of the USA, but the actual average royalty rate decided by the courts is lower than that in the USA.
The article provides an English-language translation of section 128 of the Korean Patent Act (KPA), which sets out the standards for awarding patent damages in seven paragraphs, and provides extensive discussion of the Korean case law (with comparisons, from time to time, with the rules and cases in the U.S., Germany, Japan, and other countries). The author notes, among other things, that in Korea (unlike the U.S., according to some cases) the infringer bears the burden of proving the existence of noninfringing alternatives; reports the number of cases in which Korean courts have awarded lost profits, infringer's profit, reasonable royalties, or "corresponding loss" (similar in concept to the German practice of estimating damages nach freier Überzeugung, see here, though Professor Jung is critical of the manner in which Korean courts exercise this "free discretion"); states that Korean courts, like their German counterparts, strive to award a reasonable royalty based on ex post evidence; and reports that median damages in Korea tend to be low, approximately U.S.$50,000 for the years 2009-15 according to an article by Choi. I will certainly be referring back to this article when the time comes to publish a second edition of my book.