Jo Ji-Hoon is a 19 year old right-handed pitcher for the Hanwha Eagles, not turning 20 until April of 2014. The Eagles brought him up earlier in the season and had him throwing out of the bullpen before giving him his first start in the past week.
Jo is listed at just over 6 feet tall, and 200 pounds, though he didn't seem to be heavy to me. Either way, he is unlikely to add weight, so adding velocity seems unlikely, though it is always tricky to tell.
I saw him work out of then pen, getting up to 89 MPH, which even for the KBO, is below average top end velocity. With that said, he had really good numbers in the KBO minor leagues, and at 19, even for a really bad team, to get a start (not to mention his success in the bullpen before the start) shows that he seems to have some advanced feel for pitching.
Mechanically, he swings his arm pretty far back, but he comes forward in a pretty traditional manner. He doesn't provide the deception that many of the pitchers in the KBO might have, but they don't look as hard to repeat, other than quite a long stride, as many pitchers' mechanics.
Ji-Hoon proved to be difficult to classify. He topped out at 143 KMH, which is about 89 MPH, throwing one pitch that hard. The slowest pitch he threw was a curveball around 73 MPH, not having the traditionally slow curve.
The easiest way to break down his pitches is by three simple classifications, fastball, curveball, and changeup. The biggest challenge was differing from the fastball and changeup which was tough. There were some pitches in the 80-83 MPH range that didn't really drop like you would expect a changeup. I tried my best, just by watching the pitches. This way of classifying him has his fastball averaging about 85.9 MPH, between 82-89 MPH (133-143 KMH), thrown 59 % of the time.
The changeup averaged about 79.6 MPH, 75-84 MPH (121-135 KMH), thrown 19 % of the time. The curve averaged 79.4 MPH, 73-78 MPH (117-126 KMH), thrown 22 % of the time.
However, this is an overly simplistic way of looking at how Jo threw the ball, as it doesn't appreciate the different things he was doing with his pitches. I think you can identify seven different pitches Ji-Hoon was throwing if you break his fastballs into three parts. He was throwing the straight 4-seam fastball, but he also threw a lot of sinkers, with pretty good locations at the bottom of the zone and some movement. You could also explain his slower fastballs by looking by calling it a 2-seamer, as some of them tailed inside to righties. It wasn't a good pitch, but it might help explain what was going on rather than just really inconsistent velocity (which could be true since he is again, just 19).
Some of his harder curves did look like sliders, so you could break that pitch in two if you needed to. The traditional curveball had really nice break to it (I thought it was his best pitch) and he could throw it for strikes, while the pitches that looked like sliders to me didn't sweep or go horizontal much, but they had a different vertical break, a lot like the slider that you see a lot of Korean and Japanese pitchers throw.
He also seemed to alternate from a traditional changeup and a forkball, this based just by observation on movement. The change breaks more arm side and is less sudden, while the forkball spikes in the dirt. He seemed to have both.
Anecdotally, he seemed to work fastball heavy early and then went really breaking ball/off-speed heavy later in the game. Here is a graph of his pitch velocities (by KMH instead of MPH) sorted by pitch count, the first pitch being the far left, and the last pitch being the far right (I manually logged the velocities based on the broadcast, so there are a few missing that weren't shown for whatever reason):