tree trunk, main part, talent, capability
幹 centers on the core structural part that supports everything else: a tree trunk, the main part of something, or a person's fundamental talent and capability.
幹 combines 干 (which may suggest a pestle or shield) with a phonetic element on the left (originally 倝 or similar), historically associated with the core or trunk of something. The modern form keeps the left side as 十 over 日, but the exact historical development of the left component is uncertain.
The left side looks like a sturdy structure (十 over 日), and the right side 干 resembles a strong trunk. Together they form the main supporting part: a tree trunk or the core talent of a person.
For カン, imagine a can of talent: the can (カン) holds all your capability, just like a trunk holds the tree together.
Shinkansen; bullet train
management; (executive) staff; leaders; leadership; top brass; upper echelons
executive secretary; coordinator; organizer; person in charge of making arrangements
tree trunk; bole
mainstay; nucleus; key
foundation; root; basis; core; fundamentals
main line; trunk line
chief editor; managing editor
Tōkaidō Shinkansen
San'yō Shinkansen
Tōhoku Shinkansen
brain stem
Jōetsu Shinkansen
stem (non-inflecting part of a word); word stem
mini-shinkansen
Linear Chūō Shinkansen
lymph duct; lymphatic duct
senior executive staff; upper management
lower brainstem
Chūō Shinkansen