sennen ni vs shinken ni

Hello,

What is the difference in language usage of
shinken ni

and

sennen ni

ie.

konkai wa gakkou no benkyou wo shinken ni suru koto ni shimashita.

ryugakku wo shitte nihongono benkyou wo sennen ni suru koto ni shimashita.

Do these make sense?
Thank You

"shinken ni" is an adverb ("seriously" "in earnest").
"sennen suru/shimasu" is a verb ("...ni sennen suru/shimasu" = devote oneself to ...)

So the second sentence needs a bit of correcting:
- Ryuugaku wo shite, nihongo no benkyo ni sennen suru koto ni shimashita.

ryugakku wo shitte nihongono benkyou wo sennen ni suru koto ni shimashita.
It sounds a bit strange.
Maybe, ryugaku wo shite nihongo no benkyou ni sennen suru koto ni shimashita?

shinken ni - seriously/earnestly
真(shin) - real/true
剣(ken) - sword
sennen suru - devote/concentrate
専(sen) - wholly/mainly
念(nen) - attention/wish/feeling/sense