Spencer has a good chance to beat the Korean. I think his record against that kid is 2-0. And both times in straight sets
Looks like they only met once at roland garros last year, but you're right Spencer won that easily.
However, Spencer was coming off a very good clay court season and was in really good condition back then. He's not winning as much right now. And Hyeon Chung has been doing great in Korean futures all year, including winning one just last month. I'd say all the momentum is in the Korean's favor right now. Unless he is just terrible on grass, i bet he wins in straights (no offense to spencer).