Kg (kilogram) is not a unit of weight. It is a mass. The conversion between kg and Newton depends on the force of gravity. On Earth, you can divide the number of Newtons by 9.8. For Kilonewton, the...
Kn (kilonewton) is a measure of force, not of mass like the kilogram. Near the Earth's surface, each Kilogram has a weight of 9.82 Newton (0.00982 kilonewton), so one Kilonewton is is the weight...