since you've transitted through Seoul a few times, you should realise 50 minutes is actually plenty of time. if there's a long queue at transit security, just ask if you can be hurried through as you have a short connection.

I've done it with 45 min connections a few times and never had an issue

to be honest, most efficient airports (ICN, HKG, SIN) can manage a 45 min connecting time no problems. I've only found such a short transit time to be an issue in US airports

btw, it's "SEOUL", not soul...