In South Korea, the old order changeth. But in yielding place to new Roh regime, will things really change?

A new era is about to open in South Korea - or is it? Does the approaching changeover from Chun Doo Hwan to Roh Tae Woo mean democracy is truly dawning? Or will authoritarian military rule continue in a disguised form?

The answer depends on which South Koreans you talk to. In the Dec. 16 election, nearly two-thirds of the electorate voted against Mr. Roh - which indicates a decisive majority did not trust his promise to establish a government that would truly respond to the popular will.

Some of those voters are bitter, blaming defeat on the opposition's inability to agree on a single candidate. Some blame defeat on the government's massive use of campaign funds.

``Even after Roh comes in, I think the fight between democracy and military rule will continue,'' says a middle-class housewife.

But others are willing to give Roh, who takes office as President Feb. 25, the benefit of the doubt. ``I voted for Kim Dae Jung,'' says a veteran journalist, ``but I'm so mad at him now. Kim Dae Jung and Kim Young Sam [the two leading opposition candidates] handed the election to Roh on a silver platter because they couldn't get together. I'm willing at least to see what Roh can do.''

Neither Kim has roused the public to demonstrate in a massive way against alleged election frauds. (Roh gained 36.6 percent, Kim Young Sam 28 percent, and Kim Dae Jung 27 percent. A third Kim, Kim Jong Pil, won 8 percent.)

This is largely because Roh has been extremely circumspect, acknowledging that he won by a plurality and not a majority, and seeking reconciliation with the defeated candidates. He has promised to give the voters a chance to rule on whether he should continue as President once the Seoul Olympics are concluded next October.

More important, he is trying to distance himself as much as possible from the existing government run by President Chun. It is a delicate operation, since Mr. Chun has said he will exercise the full powers of the presidency up to the very moment he hands over the reins to his successor on Feb. 25. Chun still controls the armed forces and the government bureaucracy and has a powerful voice within the ruling Democratic Justice Party.

Roh and Chun are Korean Military Academy classmates and Roh played a key role in the coup of Dec. 12, l979, that brought Chun to power. But Roh did not run for office on the seven-year record of the Chun government. Instead, he emphasized that he had ``big ears,'' that he would listen to the people, that he would run a govenment that was not only effective, but democratic. In contrast to the imperious Chun, Roh has the pleasant bedside manner of the doctor he once wanted to be.

Roh has continued his statements of democratic intent into the post-election period and buttressed them with concrete actions. Within the ruling Democratic Justice Party, he has given preference to those with civilian rather than military backgrounds. He has been searching for a prime minister who might give a fresh, civilian look to his administration.

He had a rather public tiff with President Chun's staff over procedures for the inauguration Feb. 25. Chun reportedly wanted a joint hail-and-farewell ceremony in which Chun would make a speech as well as Roh. Roh turned him down, suggesting rather that leading social and economic organizations invite Chun to a thank-you dinner Feb. 24. Roh is said to want to keep the inauguration ceremony simple, without any of the ostentatious display so prized by the outgoing President.

Much of the public's discontent with the Chun regime focuses on charges of corruption in high places.

One early test of Roh's determination to break with the past may come when and if Chun's younger brother, Chun Kyong Hwan, former head of the nationwide Saemaul Movement for Rural Uplift, is investigated for alleged misappropriation of government funds meant for the movement.

The younger Chun wants to run for the National Assembly, a move Roh has resisted, saying norelative of high officials should be allowed to be candidates in legislative elections. There are reports Roh has promised Chun he would keep official muckrakers from reaching into the president's family.

Even the police is subject to the current mood. Recently 35 junior officers, graduates of the first class of the National Police Academy, made the rounds of newspaper offices with a declaration of ``police neutrality'' as a ``prerequisite for the realization of true democracy.'' Senior police officers were reported to be shocked by this action.

One problem Western and Korean observers foresee is that Roh may be unable to meet all the expectations he has roused. He must make a clean break with the past, but he also stands for stability, a consideration important not only to businessmen profiting from the country's phenomenal economic growth, but to an increasingly affluent middle class.

The opposition, though defeated, stands poised to take advantage of any evidence of public disillusionment once the new goverment is installed.