I only have secondhand knowledge (my brother worked at Samsung HQ for almost two years after grad school & a post-doc), but Samsung managers are often corrupt and treat their employees like trash. Foreigners have it a little better, they're allowed to go home at relatively more normal hours, but if you're from Korea and Korean, you do whatever the boss tells you or they retaliate hard since there are plenty of starry-eyed hardworking Koreans ready to take your place to work for the biggest company in & the pride of Korea. My brother wasn't completely immune either, they stiffed him on bonus pay by 50% on a max bonus year & lowballed him compared to all other foreigners by almost 2x compensation for similar credentials (our suspicion is because he's Korean - they refused to give him a reason. When he tried to go higher through a former Samsung VP relative of ours, who got a high ranking HR person to investigate, he got warned by his HR manager with an implicit threat), and he was a hotshot who finished his chemistry PhD at 25 at a top 25 US program who had his choice of jobs/academic positions. He ended up making it through by making a deal with his boss to leave him alone and my brother would avoid exposing corruption/bad decision making & getting him sacked (boss refused to teach or lend any resource for learning technical Korean chemistry terminology because his experience in American graduate school had him learning it on his own - it was explicit retaliation against western academia), and my brother still hated his life there (thought about suicide almost every day there); his first reaction setting foot on US soil again was "I love the taste of freedom!".

Whenever someone in HQ tells you to do something, you do it, and if not, you get punished, whether that's through decreased compensation or they fire you. You can be the engineer that tells managers that you can't draw parallel lines that intersect (metaphorically speaking), but they don't want to hear it unless the competitor proves them wrong with sales results - they are notorious for not innovating, but copying competitors. Samsung runs on waterfall from top to bottom. Oh, and if they tell you to do something early in the morning, you jump.

Samsung also tends to mainly promote Koreans - if you're not Korean and want to get ahead, you'd best look elsewhere because you're not likely to accomplish it. I hear this also applies to their American divisions as well, but I do not know anyone who has worked for them here. The family who owns the company has had some history with corruption in Korea as well, so this isn't too surprising.

More on the cultural side, Koreans can be very rude by western standards - it also is demanding on expectations. You're often expected to dress a certain way (this part is no different from most of the world, but disregarding norms is probably more harshly regarded in Korean culture than most), as well as join bosses & other co-workers going out to drink and doing karaoke at night. Deferring to father-like/older figures is built into the language with even how one addresses another, and that bleeds into how companies operate (& people treat each other - even being one month older can come into play unless you have leverage of some sorts). There are also built in opinions on processes, from parenting to schooling to work. Koreans tend to also be quite xenophobic/racist, even against Koreans who cannot speak Korean (maybe even moreso towards Koreans who cannot speak the language). Society sort of disowns those who are not immersed in the culture. Non-Asian foreigners are special, but they are excluded from much of anything of consequence (probably to avoid stirring the pot with other nations).

There's probably a lot more I'm missing here, but tl;dr if you aren't an extremely mentally tough person, working for a Korean company in Korea can crush you thoroughly. It is a different world, and people who do so from western society are left without a support base.