About 60 contestants spent 90 minutes sitting in a public park in Seoul without talking, sleeping, eating, or using any electronic devices during the event - under the slogan of "Relax Your Brain".
The "space-out" competition was launched by local activists in 2014.
Today's event - organised by Seoul city council - drew more than 1,500 online applicants who vied for the available places in the competition.
"Let our brain - never free from information overload from a smartphone, TV or computer - relax! Let's enjoy just thinking nothing!" the council said in a statement.
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Participants are also not allowed to look at their watches or move around too much. The person measured as having the most stable heart rate is adjudged the winner.
Today the honours went to a famous local rapper.
"I was so exhausted physically and mentally while preparing an album, so I just wanted to relax for a while," said Shin Hyo-Seob, aka Crush.
"This event is highly recommended for those who have migraines or complicated thoughts," the 28-year-old said, holding his glass trophy.
The country's smartphone users spend an average of four hours a day tweeting, chatting or playing games, with about 15 per cent showing symptoms of addiction, according to state data.