The volunteer military system: everything boils down to money

‌70% of South Korea's defense budget is for current maintenance costs. 70%
is the cost of clothing, feeding, and housing existing personnel.
If we want to maintain a large army of 300,000 to 400,000 through a volunteer system,
we would have to significantly increase the ratio of officers and NCOs, rather than having a soldier-centric military like we do now, similar to the US military or the JSDF.
The ratio of officers and NCOs would likely need to be around 40%. In that case, the infrastructure required to train those officers
is nowhere near sufficient under the current state; it will cost a lot of money.
Furthermore, under a volunteer system, both officers and soldiers become professional soldiers.
Their food, clothing, and housing cannot remain at the level of the conscription system. The same goes for salaries;
they would need to be drastically improved. But as for the infrastructure of South Korea's frontline units... well...
All of that requires money and time to build the necessary infrastructure.
A volunteer military system cannot be implemented overnight.