INCHON, SOUTH KOREA -- For years they have come from the countryside to industrial cities like this, young men and women desperate for work and willing to live in barracks-like dormitories or tumbledown takchan, "chicken coops" where factory laborers sleep cheek to jowl.

Working longer hours than laborers anywhere else in the world, they have powered a remarkable economic success story, bringing unexpected prosperity to a nation that was destitute three decades ago. But while the wealth is more evenly distributed than in many developing nations, millions of workers still barely scrape by. Last year alone more than 23,000 were killed or crippled in industrial accidents, according to union officials.

Now, as the authoritarian government that has kept wages low through force and coercion loosens its control, workers are demanding a greater piece of the "economic miracle" in an explosion of rank-and-file strikes, sit-ins and other job actions. Spontaneous, leaderless and apparently beyond any institution's control, the labor stirrings have injected a new uncertainty into South Korea's fragile progress toward democracy.

"I think there's a recognition on just about everyone's part -- the government, the political parties and management -- that basically workers' grievances are justified," a western diplomat said last week. "They reflect genuine, pent-up feelings, and it's a time of reckoning."

But as it tries to steer a course away from sweatshops and repression of unions to the smoother labor relations of a mature industrial economy, South Korea is without pilots, many specialists here say. Many workers view existing unions suspiciously as progovernment, and the government can hardly act as honest broker after years of siding with management.

"It seems that labor disputes stem from a pent-up sense of poverty and frustration," Labor Minister Lee Hun Kee said last week. "Under the government's growth-first policy, there is no denying that not enough attention has been paid to the question of equitable distribution of income and improvement of working conditions."

Since the government of President Chun Doo Hwan stunned the nation six weeks ago by accepting opposition demands for free elections and other reforms, there have been more job actions than in all of 1986, involving tens of thousands of workers. The nation's five major automakers, including the Hyundai plants that build Excels for export to the United States, have been shut down, either by strikes or parts shortages caused by strikes at supplier firms.

Shipbuilders, miners, bus drivers, even pop singers have staged protests or walked out, and small companies have been hit as hard as large. In this port city west of Seoul last week, disputes closed more than 20 small and medium-sized companies, including machine shops and makers of elevator parts, furniture and musical instruments.

"It's like a brush fire," said an organizer here, who asked not to be identified because he said he fears government reprisal. "It will rise up in one place and perhaps die down, but before it dies down another rises up. If it starts in a large company, it spreads to the subsidiary; and if it is settled there, it has already spread to another subsidiary."

Although police have responded with tear gas at a few mines and factories, the disputes have been largely peaceful, the demands moderate and the strikes settled within a few days. Choi Jang Jip, a professor at Korea University, said that restraint distinguishes the movement from past periods of labor strife.

"The scope of worker participation is enormously wide, explosive, eruptive, much more than in past demonstrations," he said in an interview. "But this time, in terms of mode of protest and demands, it's moderate, it's curbed."

So far, the cost to South Korea's economy also has been relatively modest. The government estimated last week that $55 million in exports were lost during a 15-day stretch in late July and early August, hardly a dent in the nation's more than $25 billion in exports during the first seven months of the year.

But a nation as dependent on exports as South Korea, which has prospered against all expert predictions despite its lack of natural resources, is sensitive to any threat of disruption. Newspaper editorialists, officials and businessmen spared no rhetoric last week warning of the dire consequences of continued strikes.

A top aide to President Chun, for example, warned that workers were "asking for too much," adding that "in a sense the free-market, democratic system is in danger." If the disputes degenerate into "chaos and social disorder," he warned, Chun would have to step in.

The aide recalled the strikes of 1980, during the time known as the "Seoul Spring" when many South Koreans thought democracy was at hand after the assassination of President Park Chung Hee. Citing labor strife as a reason, then-general Chun seized power in a coup.

This time, the aide said, Chun plans to step down peacefully, but continued strikes could jeopardize what would be the republic's first change of power through elections.

"I would like to emphasize that President Chun hopes those tough measures will not have to be taken, and he does not want the military to be involved in the political affairs of the country," the aide said.

Some observers said the government and news media have exaggerated the labor disputes to "provoke a fear among the middle class," as Korea University's Choi said.

"For some people in the ruling camp, this labor unrest suits their needs," the western diplomat agreed. "The hard-liners can say, 'This is what happens when you liberalize. The Korean people aren't ready.' "

Still, Choi said not all the rhetoric is calculated.

"It is really true that government authorities and employers are alarmed," he said. "It is very difficult to judge what direction these demonstrations will take."

So far, the strikes have centered on three issues: wages, working conditions and a demand for new democratic unions to supplant the government-controlled associations of the past. The government, which formerly set wage guidelines and discouraged any firm from paying more, has encouraged companies to grant some increases.

South Korea's economic success has increased the nation's per capita gross national product to about $2,500, and many workers enjoy comforts beyond any that their parents could have imagined. But class disparities have increased in recent years, according to several scholars, and the gap between worker income and expectations is perhaps even wider.

In Inchon, where the "chicken coops" and working-class houses seem to tumble upon one another on the hillsides leading to the harbor, and in other industrial towns, the disparities are most evident in textile and electronic plants where many teen-age girls work. Medium-sized companies often maintain relationships with junior high schools in rural areas, and they recruit busloads of 16- and 17-year-old girl students with the promise of a senior high school education.

The girls earn an average of $160 per month, according to Lee Hyun Soo of the Urban Industrial Mission here. They often work 12 hours a day, six days a week, or more.

"A lot of them end up working all but two days a year," Aryeh Neier, vice chairman of the New York-based human rights group Asia Watch, said at the end of a fact-finding trip here last month. "And if they try to organize, they have their heads handed to them."

The girls cannot leave their dormitories without permission, and their foremen, night school teachers and dorm supervisors make up a 24-hour control team, Lee said. Except in electronics firms, where the product requires clean and cool air, the factories are often noisy, dirty and dangerous. There is no minimum wage law, and existing labor standards, such as one limiting 14-to-18-year-olds to eight hours' work per day, are rarely enforced.

The courts, the police and the companies have worked together to bar all but the most docile unions, according to union officials here. When workers have managed to unite, their efforts have usually been defeated by company toughs, often the well-treated company soccer team doubling as promanagement vigilantes, or by arrests of union leaders on the grounds of disturbing the peace, Lee said.

The laws are so restrictive that of the 276 labor actions that took place last year, none was legal, according to Lee Yong Joon, vice president of the Federation of Korean Trade Unions.

Lee, whose federation has been sanctioned by the government, said he is optimistic that the labor problems can be solved because South Korean workers are "sincere, faithful, intelligent and have a good sense of company-loving spirit." But, with no one enjoying the workers' trust enough to mediate the disputes, many here predict that strikes will remain a challenge, not only during the next few months but for any new government that emerges from elections later this year.