Note 13. Segment, Geographic, Product and Significant Customer Information

The Company has one operating segment, which is the sale, design, manufacture, marketing and support of optical critical dimension and thin film systems. The following tables summarize total net revenues and long-lived assets (excluding intangible assets) attributed to significant countries (in thousands):

	Three Months Ended				Six Months Ended
	June 30, 2018		July 1, 2017		June 30, 2018		July 1, 2017
Total net revenues:
South Korea	$	30,980	$	31,500	$	68,798	$	50,119
Japan		15,017		9,267		28,396		12,620
United States		7,392		8,297		14,130		21,870
China		28,333		7,330		36,375		14,017
Taiwan		1,974		4,878		3,034		16,711
Singapore		2,380		963		14,535		2,454
Other		2,528		2,192		5,649		5,950
Total net revenues	$	88,604	$	64,427	$	170,917	$	123,741

	June 30, 2018		December 30, 2017
Long-lived tangible assets:
United States	$	41,851	$	43,427
International		1,199		1,383
Total long-lived tangible assets	$	43,050	$	44,810

With respect to customer concentration, Samsung Electronics Co. Ltd., Yangtze Memory Technologies Co. Ltd., Intel Corporation, and Toshiba Corporation each accounted for more than 10% of total sales for the three months ended June 30, 2018, and Samsung Electronics Co. Ltd., SK Hynix, Toshiba Corporation, Yangtze Memory Technologies CO. Ltd., Micron Technology, Inc., and Intel Corporation each accounted for more than 10% of total sales for the six months ended June 30, 2018. Samsung Electronics Co. Ltd., SK Hynix, and Toshiba Corporation each accounted for more than 10% of total sales for the three months ended July 1, 2017, and Samsung Electronics Co. Ltd., SK Hynix, Taiwan Semiconductor Manufacturing Company Limited, and Intel Corporation each accounted for more than 10% of total sales for the six months ended July 1, 2017.

With respect to accounts receivable concentration, Toshiba Corporation, Yangtze Memory Technologies Co. Ltd., Intel Corporation, and Samsung Electronics Co. Ltd. each accounted for more than 10% of total accounts receivable as of June 30, 2018. Samsung Electronics Co. Ltd., Micron Technology, Inc., and Toshiba Corporation each accounted for more than 10% of total accounts receivable as of December 30, 2017.