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The Korean expatriate was at a Wellington art school when he was conscripted in 2007 for 23 months of compulsory military training in the Republic of Korea Armed Forces - one of the largest standing armed forces in the world.
Most of his training was in the Korean Riot Police Squad and any form of artistic expression was banned.
Junior officers were prohibited from using mirrors to stop them interacting with their own reflection, he said.
After conscription, he quickly became anxious to ''paint and express'' again.
As a junior officer, he was given toothpaste and a scrubbing brush to clean the barracks, including the mirror of a senior officer.
''The mirror cleaning time was when the senior officer stepped outside for a cigarette.''
As the officer smoked, he scrawled a self-portrait with toothpaste on the mirror to release the ''urges of expression''.
He washed the mirror down when the senior officer approached because if he had been caught painting, the punishment would have been severe, he said.
The training reinforced his need for expression.
''I learnt what I really wanted to do: art. It was a big epiphany that lasted for 23 months.''
He used the skills gained from the secret art sessions for his Dunedin Fringe Festival work Toothpaste Transcription of Panopticism, a toothpaste transcription he started in the Fringe Fishbowl yesterday.
He will finish transcribing passages from the French philosopher Michel Foucault's book Discipline and Punish today.
Son said the passages were about the panopticon - a type of prison designed by the English philosopher and social theorist Jeremy Bentham in the late 18th century.
The building's design allowed a guard to observe the cells without the inmates' knowledge. . The guard could not watch every cell at once but as the inmates never knew if they were being watched or not, they regulated their behaviour, Mr Son said.
Son will perform other Fringe Festival works at the Blue Oyster Art Project Space in Dowling St until Sunday.