Stepper Motors : KG.CM Torque : Does it maintain the torque when connected to a rod?
Torque is distance times force.  A torque of 10kgf-cm means that at a radius of 1cm the force exerted in the (tangent) direction of rotation will be 10kgf.  At a radius of 10cm, the force is 10kgf-cm / 10cm = 1kgf.  So at a radius of 30cm, you have 10kgf-cm / 30cm = 0.33kgf.  Note that torque is constant, but the force changes with the radius at which you measure it.  Also, the force is always measured in the direction tangent to the radius you're considering.  

If you're asking about using the threaded rod as a lead screw, then that's different.  You're still converting torque to force, but the conversion will depend on the pitch of the lead screw, and there will be substantial losses to friction.