Lee Chang-june can be miles from his 12-year-old son but still know when he plays a smartphone game. With the press of an app he can see his son's phone activity, disable apps or totally shut down the smartphone.
The app, "Smart Sheriff," was funded by the South Korean government primarily to block access to pornography and other offensive content online. But its features go well beyond that.
Smart Sheriff and at least 14 other apps allow parents to monitor how long their kids use their smartphones, how many times they use apps and which websites they visit. Some send a child's location data to parents and issue an alert when a child searches keywords such as "suicide," "pregnancy" and "bully" or receives messages with those words.
In South Korea, the apps have been downloaded at least 480,000 times.
The number will likely go up. Last month, South Korea's Korea Communications Commission, which has sweeping powers covering the telecommunications industry, required telecoms companies and parents to ensure Smart Sheriff or one of the other monitoring apps is installed when anyone aged 18 years or under gets a new smartphone. The measure doesn't apply to old smartphones but most schools sent out letters to parents encouraging them to install the software anyway.
Many countries have safety filtering tools for the Internet but it is rare to enforce them by law. Japan enacted a law in 2009 but unlike South Korea it allows parents to opt out.
South Korea's new system is by no means impervious. For one, it can only be fully applied to Android phones not Apple Inc. phones. But cybersecurity experts and Internet advocacy groups argue the monitoring infringes too far on privacy and free speech. Some warn it will produce a generation inured to intrusive surveillance.
"It is the same as installing a surveillance camera in teenagers' smartphones," said Kim Kha Yeun, a general counsel at Open Net Korea, a non-profit organization that is appealing the regulator's ordinance to South Korea's constitutional Court. "We are going to raise people who are accustomed to surveillance."
South Korea, one of the Asia's richest nations, is crisscrossed by cheap fast Internet and smartphone use is ubiquitous. Many Koreans get their first smartphone when they are young. Eight out of 10 South Koreans aged 18 and below own a smartphone, according to government data. Some 72 per cent of elementary school students owned a smartphone in 2013, a jump from 20 per cent in 2011.
How technology is affecting the young has become a national obsession. The government and parent groups have pushed numerous initiatives to limit device and Internet use as well as prevent excessive gaming. Many parents welcome the ability to peer inside their children's online world.
Lee, who worked in the online game industry for nearly a decade, said that having a control over his son's smartphone has been positive and increased dialogue in the family. His son plays a mobile game about two hours on weekends. If he wants to play a mobile game outside those hours, he comes up to dad and talks about why.
"What is important is that parents and children talk to each other and try to build consensus. He is only in a sixth grade but he wants to have his privacy," Lee said. "I told him: We are installing this and father will know which app you use," he said. "I see it as positive in helping nurture his habit of self-control."
Legal experts, however, say South Korea's telecoms regulator has taken the sweeping step of legalizing the broad collection of personal, sensitive data that belongs to teenagers without any public consultation or consideration of the possible consequences.
"South Korea underestimated the chilling effect," said Kang Jeong-Soo, director at Institute for the Digital Society.
Cyber security experts also warn that the apps could be misused and installed on phones without the owner's knowledge.
"It could be an official spying app," said Ryu Jong-myeong, CEO at SoTIS, a cyber security company.
To get around the regulations, some students say they will wait until they turn 19 to get a new phone.
"I'd rather not buy a phone," said Paik Hyunsuk, 17. "It's violation of students' privacy and oppressing freedom."
Cho Jaehyun, a senior year high school student, had to install a parental control app when he was in middle school. But he said he was lucky that his parents agreed to uninstall the app when he entered high school.
"We don't always use the smartphone for something bad," said Cho, 17. "Because I could use my phone freely without control, I got interested in developing iPhone games."
Not all parents are on board either.
Park Choel-hee, father of a 10-year-old daughter, said South Korea resorts too much to regulation and makes "senseless" choices about what content is offensive.
"A few officials arbitrarily determine which websites are harmful and unilaterally shut them off. They rob the rights of Internet users. It is no different from the Great Fire Wall of China."
Park, who gave his daughter his second phone so she didn't have to release her personal information to mobile carriers, said he feels "uncomfortable" that his child is growing up in a society of prying eyes.
"Children will not have an ability to think for themselves," he said.