We also had short-term deposits in banks of
W
79 billion,
W
79 billion and
W
743 billion (US$625 million), respectively, as of December 31, 2019, 2020 and 2021. Our primary use of cash has been to fund capital expenditures related to the expansion and improvement of our production capacity with respect to existing and newly developed products, including the construction and
ramping-up
of new, or in certain cases, expansion or conversion of existing, fabrication facilities and production lines and the acquisition of new equipment. We also use cash flows from operations for our working capital requirements and servicing our debt payments. We expect our cash requirements for 2022 to be primarily for capital expenditures and repayment of maturing debt.
As of December 31, 2019, we had current assets of
W
10,248 billion and current liabilities of
W
10,985 billion, resulting in a working capital deficit of
W
737 billion. As of December 31, 2020, we had current assets of
W
11,099 billion and current liabilities of
W
11,007 billion, resulting in a working capital surplus of
W
92 billion. As of December 31, 2021, we had current assets of
W
13,187 billion (US$11,095 million) and current liabilities of
W
13,995 billion (US$11,774 million), resulting in a working capital deficit of
W
808 billion (US$679 million). The working capital surplus as of December 31, 2020, compared to a working capital deficit as of December 31, 2019, was primarily attributable to a
W
1,615 billion decrease in other accounts payable, which mainly reflected a decrease in the outstanding balance of enterprise procurement cards (a type of corporate credit card used for paying for utilities and certain other goods and services) at December 31, 2020 compared to December 31, 2019 as a result of our accounts payable management activities during 2020, and a
W
882 billion increase in cash and cash equivalents mainly as a result of general increase in our cash levels in light of corresponding increases in our revenue and profitability as well as our response to increased uncertainties in the financial markets and our business environment, the effects of which were partially offset by a
W
1,218 billion increase in our current financial liabilities, which mainly reflected an increase in the current portion of long-term financial liabilities payable as of the end of 2020 compared to the end of 2019, and a
W
1,161 billion increase in our trade accounts and notes payable mainly as a result of extensions to applicable payment terms with certain outside vendors. The working capital deficit as of December 31, 2021, compared to a working capital surplus as of December 31, 2020, was primarily attributable to a
W
1,035 billion increase in trade accounts and notes payable mainly due to increases in purchases of raw materials and components in 2021 compared to 2020 in anticipation of stronger demand for our products in light of the increased levels of working remotely, home schooling and social distancing caused by the
COVID-19
pandemic, a
W
875 billion increase in our current financial liabilities, which mainly reflected an increase in the current portion of long-term liabilities payable as of the end of 2021 compared to the end of 2020, and a
W
676 billion decrease in cash and cash equivalents due to a decrease in demand deposits, the effects of which were partially offset by a
W
1,180 billion increase in inventory as a result of inventory stocking in light of supply chain uncertainties in part due to the
COVID-19
pandemic as discussed above and a
W
1,057 billion increase in net trade accounts and notes receivable, which was mainly caused by increases in our revenue and sales of trade accounts and receivable in 2021.
Our management constantly monitors our working capital, and we have historically been able to satisfy our cash requirements from cash flows from operations and debt financing. We believe that we have sufficient sources of working capital, including in the form of debt financing, for at least the next 12 months following the date of this annual report. In 2021, we issued domestic bonds in the aggregate principal amount of
W
500 billion (US$421 million), and we entered into a number of short-term and long-term facility loan agreements, from which we have drawn down the full aggregate principal amount of US$518 million (
W
614 billion) as of December 31, 2021 in short-term loans and
W
500 billion (US$421 million) and US$680 million (
W
806 billion) in long-term loans, in each case as of December 31, 2021, primarily to fund our capital expenditures and refinance our existing borrowings maturing in 2021.
Our ability to satisfy our cash requirements from cash flows from operations and financing activities will be affected by our ability to maintain and improve our margins and, in the case of external financing, market conditions, which in turn may be affected by various factors outside of our control. Therefore, we
re-evaluate
our capital requirements regularly in light of our cash flows from operations, the progress of our expansion plans and market conditions. To the extent that we do not generate sufficient cash flows from our operations to meet our capital requirements, we may rely on other financing activities, such as external borrowings and securities offerings, including the issuance of equity, equity-linked and other debt securities.