K. Yokoyama*, T. Onda, S. Kashiwakura and T. Nagasaka :“Evaluation of Environmental Burden and Economic Impact with “Landfill Mining Activity” Based on the Waste Input-Output Model” Sohn International Symposium on Advanced Processing of Metals and Materials: Principles, Technologies and Industrial Practice , San Diego, USA（2006年8月28-31日）[As a Keynote speaker]
H. Osuga*, K. Yokoyama, K. Nakajima and T. Nagasaka:“Material Flow Analysis of Aluminum Dross and Environmental Assessment for Its Treatment” The 7th International Conference on EcoBalance, Epocal Tsukuba（2006年11月14-16日）(Poster Presentation) (Outstanding Poster Award)
K. Yokoyama and T. Nagasaka : “The Case Study of National-scale Material Flow Assessment－the Japan Experience ” CTCI foundation Environmental & Energy International Conference[96年度環境與能源國際研討會] , Taipei, Taiwan （2007年1月16-18日）[As a Keynote speaker, Invited]
