SEOUL » Moon Tae-Hwa stares at his computer, dizzy and nauseated from the hours of porn he’s viewed online while his wife and children slept. He feels no shame — only a righteous sense of mission.

"I feel like I’m cleaning up dirty things," the devout Christian and family counselor said.

Moon is among the most successful members of the "Nuri Cops" (roughly "net cops"), a squad of nearly 800 volunteers who help government censors by patrolling the Internet for pornography in their spare time.

Unlike most developed nations, pornography is illegal in South Korea, though it remains easy for its tech-savvy population to find. More than 90 percent of South Korea’s homes have high-speed Internet access, and more than 30 million of its 50 million people own smartphones.

"It’s like shoveling snow in a blizzard," Moon conceded.

But while there is no chance the government will wipe out porn, it also shows no sign of giving up the fight. In fact, it has responded to several recent high-profile sex crimes with a fresh crackdown.

More than 6,400 people accused of producing, selling and posting pornography online were arrested over a six-month period ending in late October.

"Obscene materials and harmful information that can be easily accessed on the Internet are singled out as one cause inciting sex crimes," President Lee Myung-bak said in a radio address in September.

Free-speech advocates disagree with the government’s unrelenting stance.

"It’s a reign of terror against sex," Ma Kwang Soo, a Korean literature professor at Seoul’s Yonsei University and author of a book that South Korea banned because of its sexual content. "No country in the world has ever reported that banning porn results in a drop in sex crimes."

Reported sex crimes have risen sharply over the past decade in South Korea, though researchers with the state-run Korean Institute of Criminology have said they believe the biggest reason is that victims have become more willing to report abuse.

The institute said more than 18,000 people were arrested on rape charges in 2010, up from less than 7,000 in 2000. Sex crimes against minors, meanwhile, more than quintupled, from about 180 cases in 2000 to about 1,000 in 2010, according to the Ministry of Gender Equality and Family.

Critics of South Korea’s stance note that when it comes to child pornography, which is banned virtually everywhere, the country’s laws have been relatively soft. Possessing child porn brings a maximum one-year prison sentence, and until recently had been punishable by just a fine.

South Korea has a history of censorship nurtured by decades of military-backed rule that ended only in the late 1980s. It also has a large and active conservative Christian population and a deep-rooted strain of Confucian morality. Yet it has also become one of the world’s most technologically advanced countries.

Censorship of movies, songs and news media has gradually eased since South Korea achieved democracy, but the government blocks foreign websites containing pornography and shuts down those operating within South Korea.

The job seems endless, however, so police turn to the Nuri Cops, who include university students, information technology workers, professors and housewives.

"Police officers can’t look at all the obscene material online, so their role, which is reporting illegal sites that need to be blocked, is very important," senior police officer Lee Byeong-gui said of the volunteers.

Over two weeks in August, the squad reported more than 8,200 cases of online porn during a police-organized contest.

Police say they have recently shut down 37 websites, and another 134 sites are under investigation on porn-related charges. Authorities also deleted many porn materials from other websites, though Moon said much of the porn re-emerged in slightly different form days after being removed.

Some Nuri Cops acknowledge that they are fighting an increasingly difficult battle against a relentless enemy. They’ve also faced complaints from their sometimes baffled spouses and friends, and endured venom from anonymous online porn enthusiasts.

"They’ve called me the enemy of South Korean men," Bae Young Ho, a Nuri Cop who works as a real estate broker, said of his online critics. He said he found about 5,000 malicious messages attacking him in the comments section of an online story about his work.

The volunteers also find the work itself to be disturbing.

"It’s easy to find smut on the Internet, but it’s difficult for me to watch," Moon said in an interview at his Seoul home. "It’s disgusting and it bothers me because the images I see linger in my head for so long."

Moon, who was ranked the top anti-porn monitor in 2010 and second this year, said he and other Nuri Cops keep going because they feel that society benefits from their work.

Opponents of pornography point to several recent horrifying sex crimes as reasons to try to stamp it out.

A man was sentenced to life in prison this year for strangling a woman after a failed rape attempt, then chopping her body into 280 pieces that he hid in plastic bags at his home south of Seoul. The man told investigators he watched pornographic movies while cutting up the victim’s body.

Another man got a life sentence for strangling a 10-year-old girl living in his neighborhood after a failed rape attempt. He was found to have dozens of child porn films in his computer.

South Korean law punishes those who distribute, sell or display obscene materials on the Internet with up to one year in prison. There’s no punishment for watching or possessing cyberporn.

The National Assembly recently passed a law raising — from seven years to 10 years — the maximum sentence for distributing, selling or displaying child pornography for commercial purposes. Legislators also made possessing child pornography punishable by up to a year in prison; previously, the maximum punishment had been a fine of 20 million won (about $18,500).

The prime minister’s office says it will seek to have all movie download sites and smartphones used by minors equipped with anti-porn filtering systems. Anti-porn campaigners also want authorities promote sex-education programs aimed at countering the effects of pornography among children.

Some South Koreans believe the government’s approach should be more nuanced. Lee Bong Han, a former police officer who teaches at Deajeon University, said it’s time for South Korea to legalize less extreme and nonviolent pornography, which he believes can be used in clinics that treat sex problems.

Ma, the professor who advocates for porn legalization, doubts that such changes will come anytime soon. He sparked a national debate in the early 1990s after authorities arrested him and banned his book "Happy Sara," about a female university student exploring her sexual freedom.

"It’s been 20 years since I was arrested … but South Korean culture hasn’t democratized yet," Ma said.

"Happy Sara," he added, is still banned.