Carlos Tevez is enjoying his football in Italy and has every intention of honouring his contract at Juventus.
Ramires is hoping to spend 'much longer' at Chelsea after passing the 200 appearance mark for the club.
Striker Tankulic scored during Dundee's recent 2-0 friendly win over Manchester City while Konrad impressed in central defence.
Both players have agreed two-year deals with the Championship title winners after moving from the regional leagues below the third tier of German football.
Konrad, 24, previously played in the second tier with Karlsruhe while 23-year-old Tankulic has moved from Wolfsburg's second team.
Manager Paul Hartley told the club's official website: "They impressed when we were away in Hungary and in the Manchester City game showed what they can do.
"They are both at a good age and fit into squad we are building. Another two good additions."