Context :

Aims : The aim of our paper is to investigate the low-amplitude and long-period variations in evolved stars with a precise radial velocity ( RV ) survey .

Methods : The high-resolution , the fiber-fed Bohyunsan Observatory Echelle Spectrograph ( BOES ) was used from 2003 to 2013 for a radial velocity survey of giant stars as part of the exoplanet search program at Bohyunsan Optical Astronomy Observatory ( BOAO ) .

Results : We report the detection of three new planetary companions orbiting the K giants \beta Cnc , \mu Leo , and \beta UMi .
The planetary nature of the radial velocity variations is supported by analyzes of ancillary data .
The HIPPARCOS photometry shows no variations with periods close to those in RV variations and there is no strong correlation between the bisector velocity span ( BVS ) and the radial velocities for each star .
Furthermore , the stars show weak or no core reversal in Ca II H lines indicating that they are inactive stars .
The companion to \beta Cnc has a minimum mass of 7.8 \it M _ { \mathrm { Jup } } in a 605-day orbit with an eccentricity of 0.08 .
The giant \mu Leo is orbited by a companion of minimum mass of 2.4 \it M _ { \mathrm { Jup } } having a period of 357 days and an eccentricity of 0.09 .
The giant \beta UMi is a known barium star and is suspected of harboring a white dwarf or substellar mass companion .
Its companion has a minimum mass of 6.1 \it M _ { \mathrm { Jup } } , a period of 522 days , and an eccentricity e = 0.19 .

Conclusions :