This part is a kind of semiconductor called 2SK1803.
Function of this product has N-Channel MOSFET Transistor.
Manufacturers : Inchange Semiconductor
Image and pinout :

Some of the text within the PDF file :
INCHANGE Semiconductor isc N-Channel MOSFET Transistor isc Product Specification 2SK1803 DESCRIPTION ·Drain Current –ID=8A@ TC=25℃ ·Drain Source Voltage- : VDSS= 900V(Min) ·Fast Switching Speed APPLICATIONS ·Contactless relay ·Diving circuit for a solenoid ·Driving circuit for a motor ·Control equipment ·Switching power supply ABSOLUTE MAXIMUM RATINGS(Ta=25℃) SYMBOL PARAMETER VALUE UNIT VDSS Drain-Source Voltage (VGS=0) 900 V VGS Gate-Source Voltage ±30 V ID Drain Current-continuous@ TC=25℃ 8 A Ptot Total Dissipation@TC=25℃ 100 W Tj Max. Operating Junction Temperature 150 ℃ Tstg Storage Temperature Range -55~150 ℃ ·THERMAL CHARACTERISTICS SYMBOL PARAMETER Rth j-c Thermal Resistance, Junction to Case MAX UNIT 1.25 ℃/W isc website:www.iscs [ ... ]
2SK1803 PDF Datasheet Download
