We have measured the single event effect (SEE) of candidate memory chips for a Langmuir probe, one of the secondary payloads of STSAT-2 (Science and Technology Satellite-2). The measurements were performed using the cyclotron proton accelerator at Korea Institute of Radiological and Medical Sciences. An ion chamber detector was used for the calibration of the flux of the proton beam. SEU (single event upset) cross-sections for 3 different kinds of memory chips were derived according to the incident proton energy. The SEU rate at the STSAT-2 orbit environment was estimated from the SEU cross-section and the modeled particle flux. The program memory chip for the flight model was selected from the candidates.