제어밸브(Control Valve)동작에서 Fail Safe기능을 설명하고, 정동작(Direct Action)과역동작(Reverse Action)에 대하여 설명하시오.
https://sec-9070.tistory.com/586
https://control.com/textbook/control-valves/actuator-bench-set/
https://www.spiraxsarco.com/learn-about-steam/control-hardware-electric-pneumatic-actuation/control-valve-actuators-and-positioners?sc_lang=en-GB