To improve the quality of CPR education, we want to assess the validity and reliability of the feedback depth measured by smartphone applications according to the smartphone attachment sites as an educational tool. However, in the prior study, armband method showed overestimated chest compression depth. The reason of the overestimation was analyzed that the weight of the smartphone amplified the inertial force to produce additional linear movement. In this study, we will make new device to fix the smartphone on the arm and on the hand and compare the chest compression depth between CPR manikin and smartphone application.

Inclusion Criteria:

• BLS provider or instructor

Exclusion Criteria:

• one who has physical problem in chest compression