Complex sentence: Ko returned to Malaysia to work as a Consultant Cardiothoracic Surgeon in Penang General Hospital in 2001 and worked there until 2004, when he moved to Ipoh to work in KPJ Specialist Hospital and has been there since then.
Split into simpler sentences: Ko returned to Malaysia to work as a Consultant Cardiothoracic Surgeon in Penang General Hospital in 2001 and worked there until 2004. He then moved to Ipoh to work in KPJ Specialist Hospital and has been there since then.