1. 1) Statistics of Ministry of Internal Affairs and Communications, 2000, 2005 (in Japanese).http://www.stat.go.jp/data/kokusei/2000/sokuhou/01.htm,http://www.stat.go.jp/data/kokusei/2005/sokuhou/01.htm
2. 2) Age Distribution of Welding Workers, Data of the Japan Society of Naval Architects and Ocean Engineers, Research Committee of Production (in Japanese).
3. 3) Fujita et al.: Systematization of Shipbuilding Skills and their Knowledge Representation, ICCAS89, (1989), pp.313-321.
4. 4) Tango Y. et al.: Automated Line Heating for Plate Forming by IHI-ALPHA System and its Application to Construction of Actual Vessels, Journal of the Society of Naval Architects of Japan 193, (2003), pp.85-95 (in Japanese).
5. Digital Manufacturing of Pipe Unit Assembly