Hi --
You may have already thought of this, but I would suggest using a littleBits Arduino module to act as a "bridge" between the sensors, MIDI OUT, and the microKorg. You'll need a simple 5-pin DIN MIDI OUT interface for the Arduino. Fortunately, the electronics are very simple -- the Arduino serial port through digital pin D1 is good enough for MIDI OUT.
My site has the design of a MIDI interface for Arduino:
http://sandsoftwaresound.net/5-pin-midi-interface-arduino/
You won't need the MIDI IN side, just the MIDI OUT. Then, you will need to write an Arduino sketch to convert the incoming sensor signals to MIDI messages. Arduino has a good MIDI library, but for output, the library is not absolutely necessary.
Essentially, you're building your own programmable MIDI controller -- far more flexible than "store-bought" controllers. I used an Arduino to build a drawbar controller, for example:
http://sandsoftwaresound.net/arduino/arduino-dangershield-drawbars/
Hope this helps you to get started!
-- pj
