The luminosity function (LF) and present day mass function(PDMF) for main sequence (MS) stars in the Praesepe and Hyades clusters are derived, showing the Wielen Dip which occurs at Mv = 9m in the LF. This dip is about 2 mag fainter than the case for the Pleiades cluster whose Wielen Dip position is consistent with that for the solar neighborhood field stars. The Wielen Dips of these clusters are reproduced by using a bimodal initial mass function (IMF).

• Lee See-Woo(Department of Astronomy, Seoul National University)
• Sung Hwankyung(Department of Astronomy, Seoul National University/Research Institute for Basic Sciencesm Seoul National University)
• Cho Dong-Hwan(Department of Astronomy, Seoul National University)