That depends if it’s the D-10-1 or the D-10-2. When I renewed my D-10, I had to show a bank balance of ₩4,500,000 to prove I could support myself over 6 months. I also had to bring updated bank books and account for all transactions over ₩20,000. If you have the D-10-1, you may have to bring documents proving that you have been looking for a job. It’s best to call immigration for updated information.