Finished a bit out of the medals but ran a decent turn 175 victory with Korea. The whole "rerolling is easy" vibe some posts have is not the case here, as I was shuffled lousy sea maps at least half the time and was given decent maps with nearby mountain starts maybe 5% of my tries? 3 or 4 of 50 or so? About half the rolls with Start Bias, about half without.
Tried the 3 or 4 decent maps that had mountains. Twice tried the hybrid Liberty/Tradition approach, and I think it doesn't suit Korea so well [unless you have, say, a coastal mountain Petra start

], particularly if there are no cultural CS nearby. You get early happiness issues, if you try for a fast 4 cities your neighbors tend to get DOW-style POed, and I couldn't keep from stalling in policies in the middle of the Tradition tree. Inhibited growth enough to hurt superfast science acquisition.
The turn 175 Korea victory was a 4 city Tradition to Rationalism policy path, with only 2 mountain cities. Cities were on a relatively crowded continent, but there were 2 keys: Managed to get a 2nd city mediocre Petra (not an ideal Petra city but OK) and a city next to Mt. Kailash for faith. Faith for GS (and 1 GE for the Hubble) was incredibly useful. The Petra allowed my 2nd city to build some key wonders and be the secondary spaceship builder. Went freedom as there was no coal and had good cashflow. Did it without building a factory. Was selling everything I owned to scrape up the last few bucks for the last spaceship part.
Basically, I think if I could have had a slightly less crowded continent [for a 5th city and/or more workable hexes for my 4 cities], or more than 2 mountain cities, I could have finished in the 160's. Korea definitely rocks the science game. I think Tradition/Freedom can be superpowerful for them.
Haven't seen the results yet, but congrats to Klaskeren on his excellent finish. Yes, an ideal map in so many ways, but you still have to play it very well to get such a great time.