SK Group Chairman Chey Tae-won and his former wife, Roh Soh-yeong, failed to reach an agreement in a court mediation session for the division of their assets Monday, putting the high-profile divorce settlement case back to trial proceedings. The two sides had entered mediation for the asset division after the Supreme Court remanded the case to the Seoul High Court last October, while confirming the divorce. They have remained far apart on whether Chey's SK Inc. stocks should be included in the