The most important role of air defense system is to attack the air target of enemy to defend the important military unit or facilities. In order to attack the target as soon as it is detected, fast and precise fire signal transfer using the fire control stick is very important. However, it was found that firing is not conducted in the test for fire control stick. In order to find the reason of such problem and improve life cycle of fire control stick, the test was conducted and it was found that chattering occurred and this led to malfunction of signal transfer from control stick to fire control unit of air defense system. In order to draw resolution for this problem, two contact plate made of beryllium copper is suggested to add to the control stick to enhance the contact and reduce chattering effect. The four fire switch prototypes were tested for 100,000 times and it showed its reliability of use.

The main milling cutter used for typical arthroplastic surgery robot, ROBODC system is 7.8 mm milling cutter. this cutter was used in case of traditional total knee arthroplasty, but 7.8mm milling cutter is not appropriate for newest surgical technique, MIS(minimally invasive Surgery). Generally, cutting method for MIS is tunnel cutting and cutter of cantilever type and small diameter is must be developed for MIS. Generally, Main problem of cutting system is chattering due to vibration of cutter by rotation and numerical analysis using finite element method was used for identifying chattering problems in this study. shaft length, cutter length, diameter and so on were proposed by axis displacement, stress, strain analysis through numerical analysis.