President Bush will use his upcoming trip to South Korea to reaffirm the U.S. commitment to that country's security while seeking improved access for American products in South Korean markets, U.S. officials say.

On the final leg of a trip that also will take him to Japan and China, Bush plans to spend 41/2 hours in Seoul, the South Korean capital. There, he will meet with President Roh Tae-woo and other officials and visit some of the more than 40,000 U.S. troops stationed in the country.Bush departs Wednesday for Tokyo, where he will attend Friday's funeral of Japanese Emperor Hirohito. He will spend two nights in Beijing before flying to Seoul on Monday.

Although U.S. officials are delighted with the political and economic development of South Korea in recent years, there is growing impatience over South Korean barriers to U.S. exports, including beef and fruit.

The result is a trade imbalance in South Korea's favor - about $10 billion last year on total two-way trade of slightly more than $30 billion.

"Korea has free access to U.S. markets. Korea should now open up," said one State Department official, who spoke on condition that he not be identified further.

Another irritant between the two countries is the large U.S. military presence in the capital area. U.S. and South Korean officials have been engaged in discussions designed to ease the frictions.

There is a small but determined radical movement in South Korea, which is driven primarily by anti-Americanism.

South Korea is a far different country today from the one Bush saw in 1982, his last visit there.

The country's unpopular military dictatorship has been replaced by a democratically elected government.