SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Earnings per share (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings per share
Common Stock underlying issued and outstanding stock options	16,033	78,322	22,041	88,347
Common stock issuable upon the conversion of convertible preferred shares		232,445		232,445
Diluted EPS calculated under the treasury stock method	16,033	310,767	22,041	320,792
Net Income	$ (3,868,568)	$ (3,641,597)	$ (2,877,596)	$ 3,974,858
Preferred stock dividend requirements	(58,111)	(58,111)	(116,222)	(116,222)
Net income (loss) applicable to common shareholders	$ (3,926,679)	$ (3,699,708)	$ (2,993,818)	$ 3,858,636
Average common shares outstanding	29,937,159	32,945,821	29,937,159	33,105,637
Average common and common equivalent shares outstanding - assuming dilution	30,169,604	33,256,588	30,169,604	33,426,429
Basic earnings (loss) per share	$ (0.13)	$ (0.11)	$ (0.10)	$ 0.12
Diluted earnings (loss) per share	$ (0.13)	$ (0.11)	$ (0.10)	$ 0.12