SHORT-TERM BORROWINGS (Details) ₩ in Thousands, ¥ in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 CNY (¥)	Sep. 30, 2020 KRW (₩)	Dec. 31, 2019 USD ($)
Short-Term Borrowings [Abstract]
Short-term borrowings	$ 28,327		$ 28,327				$ 13,753
Interest expense related to short-term borrowings	272	$ 205	611	$ 538
Line of Credit Due on January 23, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				5,057
Maximum borrowing capacity | ¥					¥ 50,000
Annual interest rate			5.22%
Line of credit due date			Jan. 23, 2020
Line of Credit Due on February 21, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				1,433
Maximum borrowing capacity | ¥					20,000
Annual interest rate			5.66%
Line of credit due date			Feb. 21, 2020
Line of Credit Due on January 18, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				1,433
Maximum borrowing capacity | ¥					20,000
Annual interest rate			5.66%
Line of credit due date			Jan. 19, 2020
Line of Credit Due on January 22, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				717
Maximum borrowing capacity | ¥					20,000
Annual interest rate			5.66%
Line of credit due date			Jan. 22, 2020
Line of Credit Due on February 14, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				717
Maximum borrowing capacity | ¥					20,000
Annual interest rate			5.66%
Line of credit due date			Feb. 14, 2020
Line of Credit Due on March 25, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				3,250
Maximum borrowing capacity | ¥					50,000
Annual interest rate			4.94%
Line of credit due date			Mar. 24, 2020
Line of Credit Due on April 17, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	0		$ 0				1,146
Maximum borrowing capacity | ¥					50,000
Annual interest rate			5.66%
Line of credit due date			Apr. 02, 2020
Line of Credit Due on April 1, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	4,404		$ 4,404				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			4.70%
Line of credit due date			Apr. 01, 2021
Line of Credit Due on June 27, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,321		$ 1,321				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			4.25%
Line of credit due date			Jun. 27, 2021
Line of Credit Due on April 29, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	820		$ 820				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			2.80%
Line of credit due date			Apr. 29, 2021
Line of Credit Due on June 27, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,079		$ 2,079				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			2.70%
Line of credit due date			Jun. 27, 2021
Line of Credit Due on April 12, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,468		$ 1,468				0
Maximum borrowing capacity | ¥					20,000
Annual interest rate			4.65%
Line of credit due date			Apr. 12, 2021
Line of Credit Due on May 24, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,468		$ 1,468				0
Maximum borrowing capacity | ¥					20,000
Annual interest rate			3.65%
Line of credit due date			May 24, 2021
Line of Credit Due on May 27, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,466		$ 2,466				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			4.68%
Line of credit due date			May 27, 2021
Line of Credit Due on June 27, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,321		$ 1,321				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			4.68%
Line of credit due date			Jun. 27, 2021
Line of Credit Due on May 28, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,441		$ 2,441				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			3.48%
Line of credit due date			May 28, 2021
Line of Credit Due on June 7, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,521		$ 1,521				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			3.50%
Line of credit due date			Jun. 07, 2021
Line of Credit Due on June 16, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,837		$ 1,837				0
Maximum borrowing capacity | ¥					70,000
Annual interest rate			3.50%
Line of credit due date			Jun. 16, 2021
Line of Credit Due on December 17, 2020 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,496		$ 2,496				0
Maximum borrowing capacity | ¥					30,000
Annual interest rate			4.35%
Line of credit due date			Dec. 17, 2020
Line of Credit Due on August 10, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	1,321		$ 1,321				0
Maximum borrowing capacity | ¥					80,000
Annual interest rate			3.85%
Line of credit due date			Aug. 10, 2021
Line of Credit Due on August 25, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	2,936		$ 2,936				0
Maximum borrowing capacity | ¥					¥ 80,000
Annual interest rate			3.85%
Line of credit due date			Aug. 25, 2021
Line of Credit Due on July 11, 2021 [Member]
Short-Term Borrowings [Abstract]
Short-term borrowings	$ 428		$ 428				$ 0
Maximum borrowing capacity | ₩						₩ 500,000
Annual interest rate			3.99%
Line of credit due date			Jul. 11, 2021