South Korea's uphill struggle to democracy. S. Korean elections are nearing, but uncertainty prevails. No one is sure how four key actors - the military, students, labor, and candidates - will interact in shaping the new democracy.

Forty-two million South Koreans are learning that there are no shortcuts on the road to political and economic democracy. Last week, government leader Roh Tae Woo was in Washington and Tokyo to explain how, after 26 years of essentially military dictatorship, his country is preparing for a transition to democratic rule through presidential and parliamentary elections.

In sports, preparations for the Seoul Olympics are nearly complete, though the games are still 12 months away. Invitations went out to Olympic committees around the world last week, and international athletes who have tested the sparkling facilities pronounce them excellent.

But in politics, South Korea's first democratic presidential election in 16 years is less than 100 days away, yet no one knows whether there will be two candidates, or three, or four.

No one can be certain that the military will not intervene, either to stop the elections or to prevent a successful candidate from taking office.

No one knows how the newly articulate Korean workers' demand for an equal voice in national affairs will affect the course of the elections or the growth of the economy.

No one can be sure whether the students - who were so active in antidictatorship protests in June - will manage to make common cause with the workers, as they fervently hope.

These four factors (the candidates, the military, the emergent workers, and the students), plus other social forces (such as the religious leaders and the middle class), intersect with one another in ways that make predictions extraordinarily difficult. South Korea is in a fluid, transitional state, in which political, economic, and social forces act and react upon each other as democracy struggles to be born. The candidates

So far, Mr. Roh is the only avowed candidate, running under the banner of the ruling Democratic Justice Party (DJP). Roh's declaration June 29 advocating democratization and direct presidential elections precipitated the transitional phase South Korea is going through today, and he has been much lauded for his courage and for his decision to break with the authoritarianism of the past. But as the campaign progresses, he must cope with the handicap of being identified with the unpopular seven-year authoritarian rule of retiring President Chun Doo Hwan.

The opposition Reunification Democratic Party has not yet decided whether to choose charismatic Kim Dae Jung or more fervent, conservative Kim Young Sam as its candidate. If both run, the party will split, giving Roh a good chance of winning the presidential sweepstakes.

A third (or fourth) candidate is Kim Jong Pil, usually known as J.P.- a former military officer, one of the leaders of Park Chung Hee's military coup in May 1961. J.P. is expected to announce the formation of a new party Sept. 28, along with his own candidacy. Since many of his potential constituents are supporters of Roh's, J.P.'s announcement could hurt the government party. The military

Rumors of a military coup multiplied toward the end of August and early in September, when labor troubles, precipitated by Roh's June 29 declaration, were at their peak. Since then these rumors have subsided, but there is little question that many key officers are suspicious of Kim Dae Jung and worry that his victory might take South Korea on a leftist adventure.

Both President Chun and Roh have said that the military will accept the results of a fair and free presidential election, whoever is elected, including Kim Dae Jung. But sources in contact with top generals say no decision has been made one way or the other. The generals hope Roh will win, and there will be know problem with them if he does. The workers

``Management and the unions,'' said a labor leader in the industrial city of Ulsan, ``are like two trains hurtling toward each other. Nobody is coming in between to try to avert a head-on collision.''

Until Roh's June declaration, most recognized unions were considered stooges of the government. Now union after union is either being created from scratch, or changing from toadying to management to asserting blue-collar rights.

But existing laws hamper labor unions, keeping them from playing a full role in society. Unions may not engage in political activity, nor may they take advice from outside forces, for fear they may be subverted by communist propaganda.

Workers tend to support Kim Dae Jung, but the ruling party hopes to win some of them over by being seen to be helping labor unions, not opposing them. But the DJP is not of one mind on this issue, and Roh could lose worker votes if the government continues a zigzag course that at times seems to support unions, and at times to regard them as potential or active enemies. The students

The heroes of the June movement to oppose dictatorship and demand democracy seem less relevant today, when the job is to build democracy rather than to demand it.

Radical students feel that Roh's June declaration cheated them of the revolution they were seeking, and they would now try to bring it about with the help of militant workers. But the two are not natural allies. Many students come from privileged white-collar families, who supported them so long as the call was for political democracy. The middle class is much more uneasy about a movement that demands a political role for labor and an equal status within Korean society.

For their part, many workers are cautious about making common cause with students. Married workers have families to support and cannot go around demonstrating at the drop of a hat. They do have political goals, many of them say. But unless totally frustrated by the government, they prefer to wage the struggle on their own.

South Korea's political and economic picture remains cloudy. The sun shines fitfully, if at all. But the will to build the framework of democracy is alive and well in the body politic. Informed Koreans say the presidential election, important as it is, only opens the door to a process that will take years to come to fruition.