South Koreans in US get into campaign back home. They do everything but cast ballots in their homeland's presidential election

On the eve of the presidential election in South Korea, last-minute stumping was going on among supporters of the main candidates - in the United States. On the third floor of a smoked-glass office building in ``Koreatown'' here, Dae Yang Kang was manning phones and stuffing envelopes in hopes of getting local Koreans to call home in support of opposition candidate Kim Dae Jung.

A few days earlier, supporters of ruling-party candidate Roh Tae Woo raised several thousand dollars at a roast beef dinner here. Eleventh-hour canvassing was also being done for Kim Young Sam, another main contender.

This is politicking in absentia - Korean-style. While the expatriates of many countries often closely follow events in their homelands, few appear to have generated as much interest in recent years as have Korean-Americans in regard to tomorrow's hotly-contested presidential election in their native South Korea.

One factor adding to the intensity of interest in tomorrow's vote is the fact that it is the first direct presidential election in the country in 16 years. It could usher in a radical change in government or a period of instability, or both.

Many of the estimated 1 million Koreans in this country have emigrated to the United States in just the past couple of decades. They remain as closely tied to the politics of their homeland as they do to their new country. Many maintain close personal and business links with the motherland.

``There is a lot of interest and much concern,'' says Tom Byun, editor of the Korea Times, Los Angeles. ``The Korean-American people have a lot of relations and family and business connections.''

``They have been very much hooked into the politics of their homeland,'' says Michael Robinson, a Korean specialist at the University of Southern California.

``They have been very politically active - more so with Korea than with American ethnic politics,'' Mr. Robinson adds.

Although Koreans in this country cannot vote by absentee ballot, their impact on the election is not entirely symbolic. By sending tens of thousands of letters and making scores of phone calls to friends back home, as well as by raising money, Korean specialists say they can at least play an indirect role in the campaign.

Moreover, many of those who emigrated to this country are well educated and have become successful in business.

``Their opinions carry a lot of influence in Korea,'' says Dr. Choi Sung-Il, head of the Korean Institute for Human Rights, which was established by Kim Dae Jung in Washington in 1983.

At least four of the seven original candidates (two have dropped out in recent days) have support committees in the United States.

Kim Dae Jung, who was once in exile in the US, maintains one of the most extensive networks. He has groups in Washington D.C.; New York; Chicago; and San Francisco - all cities with large Korean-American populations.

Here in Los Angeles, which has the largest Korean concentration in the country (350,000), a local branch of the Korean Institute for Human Rights serves as Mr. Kim's spear carrier. Its small, third-floor office exudes the disheveled feel of a campaign headquarters: candidate posters on the wall, sheaves of speeches and news clippings on a table, volunteers fielding phone calls.

Workers urge local people to call or write friends back home in support of Kim Dae Jung. The office also acts as a clearinghouse for his ideas on human rights, economic policies, and other issues - both among Koreans here and abroad.

On one wall is a sheet of paper identifying bank account numbers in Seoul where people here can make direct contributions.

Some $20,000 was raised last week, says Dae Yang Kang.

A similar network has sprung up for Kim Young Sam. Several hundred supporters turned out for kimbap (a seaweed and rice delicacy) and speeches at a rally in Queens, N.Y., last month. His workers have also been lobbying members of Congress and trying to garner support among academics, some of whom have written policy papers for Mr. Kim.

The campaigning in America ``can have a kind of morale-boosting effect,'' says Kwan Yim, a professor and head of the Institute of Korean Affairs in New York.

``Quite a number of our people have also gone back to Korea to campaign with friends and relatives in their hometowns,'' says Professor Kwan.

At least $25,000 has been raised by New York supporters of a third candidate, Kim Jong Pil, over the course of the campaign, according to organizers there.

The ruling party's Mr. Roh, meanwhile, maintains committees in at least two cities - Washington, D.C., and Los Angeles. The group here was just formed last week to ``show people there are supporters of Roh in the United States,'' says Daniel Cho, a lawyer and one of the organizers.

Many of the groups have taken out advertisements in support of their candidates in the Korean-language press, which has remained largely neutral on the election.

In contrast to the strife accompanying the campaign in South Korea, the politicking here has remained spirited but civil. For example, When Kim Young Sam's supporters rallied in Queens backers of Kim Dae Jung, following customary Korean political etiquette, sent a floral wreath.

``There has not been a lot of acrimony like in Korea,'' says Dr. Choi.