Rebirth in the Dragon Kingdom: The Strongest Blade

The youngest and top chief engineer of a military research institute in his previous life was unexpectedly reborn in the Dragon Kingdom, which is similar to Earth.
The history and culture here are no different from his previous life, but the military technology is far behind his understanding.
In this life, he was born into a distinguished family.
However, he chose the most difficult path: to become the nation's sharpest blade.
He volunteered to go to the most arduous border defense unit, where he underwent life-and-death trials on the blood-and-fire border battlefield.
Join the Dragon Kingdom's most mysterious unit—"Hidden Dragon." Every member here is a war machine capable of taking on a hundred enemies single-handedly: proficient in all-terrain warfare, able to operate all military vehicles, fluent in multiple languages, and skilled in electronic warfare and hacking... Each one is an army in themselves.
He is the inheritor of technology, the guardian of the border, and the soul of the hidden dragon who tears through the darkness for the country in the night.