SOUTH KOREA; PRESIDENT CHUN'S 3-YEAR-OLD RULE SETTLES IN TO A LIMITED DEMOCRACY

The current visit to the United States of South Korean Foreign Minister Lee Bum Suk underscores the Reagan administration's support for the three-year-old regime in Seoul.

Mr. Lee's 10-day trip will include talks with President Reagan and Secretary of Defense Caspar Weinberger about increased US military sales credits and about joint Washington-Seoul foreign policy initiatives. The visit follows that of Secretary of State George Shultz to South Korea in February.

Despite some anti-American sentiment - mainly from university students - during the past year, the relations between Washington and Seoul have been basically friendly. This reflects in part the respect which President Chun Doo Hwan's government has earned from both friendly and some unfriendly nations since its turbulent and harsh beginnings three years ago. The Chun regime now seems to fit South Korea like a comfortably worn-in pair of shoes.

This is not to say Mr. Chun's rule is without its critics.

But the majority of the South Korean people appear to have settled for limited democracy in exchange for domestic stability, an improved human-rights record, greater international prestige, and the promise of economic growth.

President Chun has introduced a series of liberal reforms that have brought some highly visible improvements to the daily lives of the ordinary people. In 1981, presidential and general elections were held. Although many former politicians, especially from the opposition parties, were banned from running, the authorities did not interfere with balloting or vote counting, and socialists won representation - two seats - in parliament for the first time since 1961.

Since then, the midnight to 4 a.m. curfew that had been in force for most of the previous 36 years has been lifted. And controls on foreign travel have been eased, so that most Koreans except those with criminal or politically suspect backgrounds can obtain passports. Also, uniforms and short haircuts for schoolchildren are no longer compulsory, several thousand prisoners - including more than 300 involved in political cases - have been released or had sentences reduced in a series of amnesties, and a ban on political activity has been lifted for 250 of 567 former politicians.

Leading dissident Kim Dae Jung, condemned to death in 1980 by a military court for instigating the Kwangju uprising, had his sentence commuted first to life imprisonment, then to 20 years' confinement. Finally, he was released last January to go to the United States for medical treatment.

But Kim remains unrepentant and bitterly opposed to the Chun regime. In an interview with Newsweek shortly after his arrival in the US, he claimed that the human-rights situation was worse under President Chun than it had been under the former dictatorial rule of Park Chung Hee.

Kim said torture of political prisoners had increased, restrictions on press freedom were much more severe, labor rights had been sharply curtailed, and surveillance of and oppressive measures against students and faculty members had been strengthened. The former presidential contender agreed there had been some positive changes, but he dismissed them as ''superficial, cosmetic changes that serve to hide the structural repression.''

To many politically aware Koreans, including some of his former followers, Kim Dae Jung is a ''has-been'' with no real chance of rallying support. But a small core of dissenters would agree wholeheartedly with his assessment, and even many pro-government Koreans and impartial foreign observers think Kim's criticisms have some validity.

It is no secret that university campuses are heavily infiltrated by plainclothes police and that students staging anti-government campus demonstrations are arrested and sometimes imprisoned. It is also widely acknowledged that the Korean press is strictly governed by ''self-censorship'' - the ''voluntary exertion of utmost discretion,'' as a journalist described it. Editors are required to adhere to government guidelines.

Free unions are banned in the public sector and in certain key industries. Existing unions are generally ineffective, and some meetings concerned with trade unionism have been prevented by the police. (A major factor in the success of Korea's government-promoted export policies has been a skilled work force, prepared to work long hours for low salaries and with few rights.)

On the other hand, the government has tried to stop police torture, especially after a recently publicized case in which a prominent businessman died after being beaten in police interrogation.

Nevertheless, ''There continue to be frequent claims that persons accused in politically sensitive cases are routinely tortured, both psychologically and physically, in initial interrogation by police and later when the investigating agency is building its case,'' according to the US State Department's 1982 report on human rights. The report was issued in February. According to the Korean National Council of Churches, there are still 300 to 400 political prisoners in Korea.

Opposition politics are what Koh Jung Hoon, leader of the New Socialist Party of Korea, calls ''an orchestrated show.'' Mr. Koh says the military told him they would allow his party to exist because ''they wanted a bridge to right-wing socialist groups in Europe and the rest of the world.''

Acceptance of this purely token role is justified by reference to recent economic difficulties, the political situation vis-a-vis North Korea, and an awareness that survival on any terms is better than political death.

Nevertheless, the National Assembly, though considered politically weak, has become a genuine forum for opposition views and for criticism, sometimes strong, of government policies and actions.

Transfer of power, scheduled for 1988, is fast becoming the most interesting political issue. Few people expect President Chun to break his often-repeated promise to step down when his seven-year term of office expires.

The question is rather how the transfer will be effected and to whom.The main opposition Democratic Korea Party (DKP) has already complained to the National Assembly that it has no chance of taking power under the present system. Such discontent is likely to become increasingly vocal.

But as Chun will automatically qualify for the position of special adviser to the next president, many believe the ''show'' will continue to be ''orchestrated.''

The military, though keeping a low profile except in relation to national security, is still considered to be ''the power behind the throne,'' and the republic's 400 generals would not tolerate civilian unrest which might cause North Korea to misread the signals and embark on a military adventure.

Mr. Chun's foreign policy has been outward-looking and successful. The disapproval that resounded around the world when he first seized power, backed by the armed forces, gradually turned to congratulations as domestic stability was restored, promised liberalizations were realized, and detailed peace overtures were made to North Korea.

Relations with the US are on a ''high'' following last year's centenary of Korean-American friendship. On a visit to Seoul this spring US Secretary of State George Shultz confirmed the US commitment to Korea, and America's ''quiet diplomacy'' policy has taken much of the credit for the freeing of Kim Dae Jung and the improved human-rights record.

Relations with Japan, always volatile, have improved dramatically following a visit by Japanese Prime Minister Yasuhiro Nakasone in January - the first official visit to Seoul by a Japanese leader since World War II - which led to agreement on a $4 billion Japanese loan to Korea.

Chun's proposal for a 12-member Pacific community, his visits to the five members of the Association of Southeast Asian Nations and four African nations, and a declared intent to improve relations with nonhostile left-wing countries have helped counter anti-Chun propaganda from North Korea. Relations with the Soviet Union appear to be warming up slightly. Several Soviet delegations showed up in Seoul last year for meetings of international organizations, the first such visits in almost three decades.

Although Chun's direct approaches to the communist North Korean regime have been rejected out of hand, South Korea's international image has improved immeasurably - witness the choice of Seoul for the 1986 Asian games and the 1988 Olympic games. Meanwhile misdemeanors by North Korean diplomats - incurring charges of rape in New York and bribery in Finland - have helped South Korea's cause, as has the recent defection to the south of a North Korean pilot.

The political and domestic stability that South Koreans are now enjoying has been helped considerably by an improving economic situation. Given the world economic difficulties and hangover effects of recent recession, Korea's economy performed well in 1982, with a real growth in gross national product (GNP) of 5. 4 percent, and the Korean government is forecasting a 7.5 percent growth for 1983.

Korea's 1983 economic management plan underlines the need to consolidate the price stability achieved over the last two years and foresees a return to export-oriented growth without the inflation problems that beset the nation's economy in the 1970s. The plan expects the growth of the money supply to be kept to 18 percent, compared with a 28 percent growth in 1982, the fiscal deficit to decline from $2 billion in 1982 to $1.4 billion, and the current-account deficit to be reduced from about $2.5 billion in 1982 to $2 billion in 1983.

Kim Woo Choong, president of the giant conglomerate Daewoo Group, which has led South Korea's exports over the past five years, reflected the optimism felt by Korean government economists and industrialists. ''We have a well-educated and skilled work force now. . . . I am confident that from now on Korea will take off (economically), if we have no political problems,'' he said in an interview.

An April US Embassy report commented that, as usual, the Korean government's expectations were ''optimistic but not unachievable.'' The report said that both the growth and inflation targets Korea has set for 1983 ''will probably be difficult to attain'' and offered a more conservative estimate of 6 to 6.5 percent real growth in GNP.

To achieve the government's projected increase in the GNP growth rate, exports will have to increase by about 10 percent this year, according to an economic observer. Exports of goods and services grew by only 5 percent last year in real terms. In the first two months of this year exports dropped by 8.5 percent in value from 1982 levels.

But by mid-March this year Korea's exports were beginning to pick up again, due, according to government economists, to the beginnings of a recovery in the US, Korea's largest market.

On the whole, most Korean and foreign economic observers are cautiously optimistic about Korea's future economic prowess. Many share the view of President Chun's chief economic adviser, Kim Jae Ik, that ''relatively (speaking), Korea's performance stands out in an overall bad environment. . . . But there is room for growth even in recession, and if world trade increases even a little - we're in business!''