U.N. Compass: East-West to North-Sooth.

The seventeenth General Assembly of the United Nations opened this week, one year to the day after activist Dag Hammarskjold crashed to his death in an airplane over an African jungle. In the intervening period, the U.N. has moved from the early post-Hammarskjold days of stunned inactivity, through near-mortal crisis, to its present calm state of readiness for the usher in of a new era. For this evolution, Acting Secretary General U. Thant could, but modestly doesn't, take credit. The new Assembly will deal, for the most part, with old problems, the unification of Korea, disarmament, Hungary, the suspension of nuclear testing, China. But these hardy perennials will appear in the new light cast by a shifting emphasis from the historic East-West struggle to the starkly emerging North-South conflict.