Here is an image showing the pin diagram of this transistor.
Classification of hFE
The KSC1623-Y transistor can have a current gain of 135 to 270. The gain of the KSC1623 will be in the range from 90 to 600, for the KSC1623-G it will be in the range from 200 to 400, for the KSC1623-L it will be in the range from 300 to 600, for the KSC1623-O it will be in the range from 90 to 180.
Marking
The KSC1623-Y transistor is marked as "C1Y".
Complementary PNP transistor
The complementary PNP transistor to the KSC1623-Y is the KSA812-Y.
Replacement and Equivalent for KSC1623-Y transistor