Do the math: 150,000 + troops along a 1400 KM border. Isn't that about one tropper every 30 feet? Someone check my math....
That computation was posted a couple days ago. It came to 1.07 per 100 meters.
Your math is just about right, but that is as the crow flys. North Korea has moutains and makes the linear battlefield asymetric.
If you layed a line across the border and contoured it with the changes in elevation, it would be about 2 or 3 times the size. Many of the grades on their moutains are in excess of 45'
Nearly all of the MSRs in DPRK run NS, and the troops should they come South from Chicom, would be channeled pretty severely.
If DPRK wanted to stop the CHICOMS they could. They practice as part of their everyday warfare technics the use of Chem agents. This is widely known by the world including the CHICOMS