In accordance with the principle of freedom of contract, the undertaking is free to set the conditions of the transaction. However, if a market-dominant undertaking uses his market power of the primary market to set trading conditions that unfairly hinder competition in the aftermarket, where the market is closely related to the main products he sells, such as machinery and repair service, it can be judged as abuse. If an market dominant undertaking in the primary market discriminates against ISO in the aftermarket, the act should be judged by considering factors such as whether intellectual property rights are exercised, management needs, and cost differences. Otherwise, it is necessary to judge the unjustness under the MRFTA whether the non-preferred undertaking is excluded from competition or whether such discrimination is intended to maintain its monopoly as well as degree of robustness in the aftermarket (including switching costs)