In a low-rise brick building just yards from Tysons Corner's gleaming towers, a group of Korean entrepreneurs toils to improve the American way of life.

Forget setting the burglar alarm and rushing out before it goes off. Matthew B. Chang has devised a digital door lock that recognizes a homeowner's voice.

Still swiping an employee identification card to gain entry at work? Daehoon Kim has developed an identification system around the iris of an eye.

And for those struggling to point and click with a mouse, Jason Song's "eyeball sensor" allows users to move things just by looking at them.

All these ideas -- and the people behind them -- are housed in the Korea Business Development Center, an incubator financed largely by the Korean government that helps Korea-based companies launch and expand in the United States. Many are in the research-and-development phase, flying between laboratories in Seoul and sales operations in the United States. The one-room office allotted each may be tiny, but these innovators cram them with big dreams.

As they make their pitch to anyone who will listen, at trade shows, networking lunches and cocktail receptions, the businesses are battling to compete with multibillion-dollar U.S.-based companies also charged with finding the Next Big Thing.

While outsourcing jobs to foreign lands stirs fierce debate across the dinner table and around the water cooler, the reverse influx has been a quieter but significant trend. Besides their products, overseas companies opening offices in the United States bring new ideas, a handful of jobs and their tax dollars. In Fairfax County alone, officials say they had four Korea-based businesses in 2000. Now they have 51.

"The Korean business community has become increasingly aggressive in general," said Gerald L. Gordon, president of the Fairfax County Economic Development Authority. He cited the Asian economic crisis and a worldwide slump after Sept. 11, 2001. "South Korean businesses started to look elsewhere . . . Europe and the United States. Their technologies are comparable in quality. It was an obvious market for the Korean business."

Several other factors have fueled their entry, according to experts and the newcomers themselves. Because a critical mass of Koreans live in the Washington area -- 66,000, according to the 2000 Census -- churches, groceries and restaurants already have been established to ease the transition. In Korea, many technology companies benefited from government contracts and hope for the same in a security-conscious United States. And the governments of Fairfax County and South Korea exercise business diplomacy; last summer, Fairfax opened an office in Seoul to lure business, while the Korean government has been sponsoring the Tysons Corner development center since late 2000.

On a recent afternoon, a half-dozen executives sat around the incubator's conference room outlining their products and business plans. Some left behind spouses and children to build their business, while others brought over entire families with the intention of staying.

"I wanted to be a successful businessman," Song said. He is president of Miru Enterprise Inc., the eyeball sensor company that also does work in satellite simulations and three-dimensional virtual reality. "In Korea, we have limitations. Here, the circumstances are really good. I don't feel any inconvenience."

Except for the time difference, points out Michael Seo, president of Lufex, which manages a procurement Web site to link contractors with government agencies. His company has been in the United States for seven years, the last four of them in the incubator.

"It's very difficult to communicate," Seo said of his workers in Korea, 13 hours ahead. "You skip sleeping."

As if on cue, a yawning Song concurred, saying he had risen at 3 a.m. to talk to a colleague in Seoul. Besides videoconferencing, the U.S.-based entrepreneurs use instant messaging and Skype, an Internet-based phone service, to communicate with their Korean counterparts. As they navigate the U.S. business landscape, they seek advice and support from the Korea Business Development Center's staff.

The tech-savvy Koreans say they have much to offer harried families in the United States. Chang, manager of LSG Inc., which makes the voice-recognition door lock, said some of his Korean customers do more than use their voices to open their houses. They also leave detailed instructions for family members to hear as soon as they open the door, such as reminders to do homework or start dinner.

"You have so many new and interesting technologies coming out of small Korean companies," said David Callahan, the senior adviser to the center. "This is going to accelerate their pace to become a global company."

The center also helps the companies find U.S. partners and investors. Callahan said the Buy America Act, which encourages the procurement of domestic goods, can be bypassed because the Koreans' innovations constitute unique products.

The companies pay about $300 per month to be in the incubator. Staff members and county officials say the goal is to get the companies out of the incubator within three years. "They grow to a point where they are ready to be out on the road and then we release them into the wild," Gordon said. "That's important to us because that's where the tax base is."

His office bursting with paperwork, equipment and charts of the human eye, Kim, the president of Iritech Inc., said he has started looking for bigger space. Besides using his iris-recognition technology at security checkpoints, he has been working on a product that can scan the iris for signs of drug use, a device he says can save millions of dollars by making drug testing unnecessary for most people.

"Even if we move to a new office, I cannot forget the great help I got here," Kim said. "Everything started here."

Outside his office, the center's general manager, Do-Hyun Woo, listens and smiles. He, too, has goals for Kim, loftier than increasing his square footage: "I think maybe he will be on Nasdaq."

Jason Song hopes his replacement for a computer mouse can make it big in America.

Daehoon Kim's optical security company is one of 51 Korea-based businesses -- up from four in 2000 -- hoping to gain a foothold in Fairfax County.