There was an incident where a soldier died from a beating because he didn't vote for a specific candidate.

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"The Jeong Yeon-gwan Beating Death Incident"
This occurred during the 1987 presidential election, a three-way race between Roh Tae-woo, Kim Young-sam, and Kim Dae-jung.
In the military, there were overt instructions to vote for Roh Tae-woo, who was the ruling party candidate and a former military man.
It is said that at every polling station, they could check who everyone voted for, much like in North Korea.
(Since the 1987 election was the first time the president was elected through a direct vote, the atmosphere was chaotic; although Chun Doo-hwan had stepped down, it was still the era of military rule, and especially in the military, it was a time when you simply had to follow orders without question...)
Despite the pressure to vote for Roh Tae-woo, Corporal Jeong Yeon-gwan voted for candidate Kim Dae-jung according to his convictions,
and he was beaten by a group and died simply because he voted for Kim Dae-jung.
The military naturally lied to the bereaved family, claiming he died during training,
and it was only in 2004 that the Truth and Reconciliation Commission officially recognized it as a death caused by a beating.