<p>We focus on a timetabling problem of university makeup classes and construct a scheduling system based on man-machine interaction which enables to reveal essential and also informal information of the problem domain. In this problem, makeup classes which are requested by the lecturers have to be scheduled to a specified time slot under the hard or soft constraints, e.g., schedules of the lecturers and the students. A constraint based scheduling model is newly introduced and several parameters of the model are settled through the repetition of the solution evaluation by the operators. In order to extract the essential information of the problem domain, formal concept analysis techniques are applied, where the optimized timetable outputted by the computer is analyzed and visualized as logical implication among attributes of the optimization model. Through the numerical experiment with the actual data, the potential of the proposed approach is examined. </p>