[16] The technology transfer agreement did not provide for a complete control of manufacturing processes, and construction involved the import of parts.

[18][19] The experimental train was used for trials from 2002, and achieved the South Korean rail speed record of 352.4 km/h (219.0 mph) on December 16, 2004.

[21] In July 2005, the Ministry of Construction and Transportation earmarked ₩80 billion for two 10-car commercial trains for 300 km/h (186.4 mph), destined for planned KTX services on the Jeolla Line from 2008.

Rotem, offering a commercial version of the HSR-350x, was chosen over Alstom as preferred bidder for the ₩300 billion order in December 2005.

[28] On November 25, 2008, the first KTX-II set was revealed to the public in a roll-out ceremony at the Hyundai Rotem factory in Changwon.

[32] The couplers and the surrounding structure form an integral unit, the so-called front ends, which were supplied by German industrial company Voith.

Compared to the KTX-I, window thickness was increased from 29 to 38 mm (1.14 to 1.50 in) by adding a fourth layer, to improve sound insulation and pressurization.

[32] The power electronics in the converters use newly available IGBTs, supplied by American semiconductor manufacturer IXYS Corporation,[36] rather than the originally foreseen[17] but unreliable IGCTs of the HSR-350x.

[10] The VVVF inverters for the motor and converter cooling fans and the air compressor, the constant voltage constant frequency (CVCF) inverters for the cab air-conditioning, the battery charge, the on-board AC supply[8] and the oil pumps are connected to the head end power within the auxiliary unit.

[30] The fourth passenger car houses a snack bar and family compartments with separated facing seats.

[3] Other passenger comfort features include wireless internet access and digital multimedia broadcasts,[8] and business compartments with small tables.

[33][40] After a naming competition held in the next ten days, the KTX-II was officially renamed as KTX-Sancheon (KTX 산천).

[51] Domestic observers expressed fear that the news of the breakdowns will negatively impact Rotem's chances in the competition to supply the Rio–São Paulo project or the US state of California's CHSR project, while Korail argued that the publication of start-up glitches is a result of its policy to make all information public, contrasting it with Chinese makers.

[52] On February 11, 2011, a KTX-Sancheon train[53] bound for Seoul from Busan derailed on a switch in a tunnel 500 m (1,640 ft 5 in) before Gwangmyeong Station,[54] when travelling at around 90 km/h (55.9 mph).