Smiling and relaxed, representatives of North and South Korea met here today to prepare for high-level talks on unifying their two countries, divided by war and ideology for 35 years.

In an amicable, 72-minute meeting, negotiating teams presented plans for the first high-level talks in nearly eight years of pledged to work seriously for unification.

This first official contact is nearly a year between the Communist North and noncommunist South, produced a general agreement that the respective premiers should meet as soon as possible to discuss the substantive problems of unification.

There were some procedural differences. The South proposed holding the meetings in Geneva while the North suggested alternating between their respective capitals, Seoul and Pyongyang.

The South argued, in a nine-point proposal, for relatively small meetings including premiers, four assistants of vice-ministerial rank and a few staff members from each side. The North proposed that each send 30 assistants.

But the differences were overshadowed by the deliberate displays of friendliness. The meeting opened at 10 a.m. in the deliberate displays of friendliness. The meeting opened at 10 a.m. in the conference room of the neutral nations' supervisory commission at this truce village. The delegations exchanged pleasantries and smiles, talking about the weather and delivering credentials.

The North's chief delegate, Hyon Chunguk, even waxed poetic, saying he hoped problems would disappear just as Pyongyang's "frozen Daedong River melts away as spring approaches."

The session ended with an agreement to meet again on Feb. 19 to work out details of the premiers' conference and a decision to reopen two circuits of the telephone hot line that connects Seoul and Pyongyang.

Sources on both sides said there was general agreement that three or four more meetings would be needed.

It was the first official meeting since last March, when another attempt to launch unification talks foundered. The present effort is regarded as the most serious move toward reconciling the two countries since official talks were held in 1972.

The new talks came about through a North Korean initiative calling for early discussions by premiers after South Korean president Park Chung Hee was assassinated last Oct. 26.

Despite the apparent eagerness of both sides, particularly Pyongyang, to start talking, a number of obstacles would have to be overcome to achieve any significant change in the status of the two Koreas.

In the past, the Communists have insisted that a board, legal unification must be achieved between the two sides before any of the details could be worked out on how they could live together as one country. Seoul has taken a more modest approach, insisting that such arrangements as family reunification and economic cooperation should be worked out before any attempt at political reconciliation.

The North also has insisted that in addition to official talks there should be simultaneous discussions among political parties and social groups from both countries, South Korea has viewed this as a trap tob bring its political dissidents, such as Kim Dae Jung, into the negotiating process, thus weakening its position.

North Korea did not abandon that concept of dual talks when it launched its plan in a series of letters in mid-January, but it seemed to be attaching less importance to the nonofficial side of the talks. The South insists on purely official meetings.

The South's chief representative today, Ambassador-at-large Kim Young Chu, declared his side is willing to strive "sincerely" for a quick conclusion to the working-level talks and an early meeting of the prime ministers.

If the preliminaries are successful, Seoul would be represented by Premier Shin Hyon Hwack and North Korea would send Li Jong Ok.

South Korea proposed that the meetings be closed and that stenographers and tape recorders would be permitted. Joint or separate press briefings would be held after each meeting.

North Korea suggested that meetings could be either closed or open, depending on agreement of both sides, and proposed that separate press briefings be conducted simultaneously.

The delegates agreed that subsequent preparatory meetings will be held at an administrative building on the North Korean side at Panmujom and at the South's Freedom House nearby.