International Conference (After 2000).
 Plenary/Invited Lectures at International Conferences
・Discrete and Computational Geometry at Monte Verita conference, Ascona, Switzerland, 2016
・Latin American Theoretical Informatics Symposium, LATIN2016, Ensenada, Mexico, 2016
・Mathematics Awareness Week in Korea 2015, The Korean Mathematical Society (KMS)
 Annual Meeting, Yonsei, 2015
・Inaugural Lecture, Universitat Politecnica de Catalunya (UPC), Barcelona, 2015.9
・XVI EGC (Encuentros de Geometria Computacional), Universitat Politecnica de Catalunya
 (UPC), Barcelona, 2015.7
・Workshop on geometric puzzles and games, SoCG2014, Kyoto University, 2014
・The 30th Annual Symposium on Computational Geometry,SoCG2014,Kyoto University,
 2014
・ICDMAS 2014,Univ. Thai Chamber of Commerce,2014
・Matematicas en la Residencia-The Mathematical Scienece Institute of Spain,Residencia de
 Estudiantes,Madrid, 2014
・Japan Conference on Discrete and Computational Geometry (JCDCG’2013) , Tokyo, 2013
・GSI’2013 (Geometric Science of Information),Ecole nationale superieure des mines de Paris
・Mexican International Conference on Discrete Mathematics and Computational Geometry,2013
・GTCA2013 (The 5th International Symposium on Graph Theory and Combinatorial
 Algorithms) Inner Mongolia University, 2013
・LAW-AAIM, Dalian Maritime University, 2013
・6th Mathmatics Day,University of Guam,Amer. Math. Soc., 2013
・TJJCCGG 2012, Bangkok (Thailand-Japan Joint Conference on Computational
 Geometry and  Graphs) Bangkok, Thailand
・The Annual meeting of Philippines Math Society, Batangas, Philippines, 2012
・XIV-EGC,Spanish Conference on Computational Geometry, Alcala de Henares,
 Spain, Spanish Math.Soc., 2011
・The 4th International Conf. on Science and Mathematics Education in Developing Countries,
 Zaman University, Cambodian Math. Soc., 2011.
・Thai Mathematics Festival, National Science and Technology Department Agency (NSTDA),
 2011.
・CGGA 2010, Dalian Maritime University, China, 2010.
・Imaginative Science Fest, Russian Acad. of Science, Vladivostok, Russia.
・The 75th Anniversary of Steklov Math. Inst. Russian Academy of Sciences, 2009.
・SVGCGT 2009, at De La Salle University, Math. Soc. of Philippines, 2009.
・General Assembly of European Academy of Sciences, Brussels, Belgium, 2008.
・Pre-ICM International Convention on Mathematical Sciences(ICMS2008),
 University of Delhi,Delhi, India 2008.
・General Assembly of European Academy of Sciences, Brussels, Belgium.
・International Conference on Intuitive Geometry, in Memorial L. Fejes Toth, Renyi Institute of
 Hungarian Academy of Sciences, Budapest, Hungary 2008.
・International Conference on Differential Equations and Topology dedicated to the Centennial
 Pontryagin, Steklov Inst. Moscow, Russia 2008.
・International Conference on Discrete Mathematics and Applications(ICDMA 2008), Bangkok
 Thailand, 2008
・International Conference on Mathematics Education 2007, National Institute of Education,
 Singapore 2007
・Inauguration of Mathematics Community of Ghana (MACOG), KNUST, Kumasi, Ghana 2007 ・Ghanaian Conference on Math Education, MathNED, Accra/Cape Coast/Ghana 2007
・The 10th Anniversary of MATHTED, Manila, Philippines 2006
・International Conference on Imaginative Mathematics, Moscow, Russia 2006
・Conference in Algebra and Combinatorics, Manila, Philippines 2006
・The China-Japan Joint Conference on Discrete Geometry, Combinatorics and Graph Theory,
 Tianjin/Xi'an, China 2005
・The 10th International Congress on Mathematical Education (ICME),Copenhagen,
  Denmark 2004
・The 20th European Workshop on Computational Geometry, Seville, Spain 2004
・Conference on Recent Progress in Mathematics Education, Bandung, Indonesia 2004
・Japan Conference on Discrete and Computational Geometry (JCDCG’2004), Tokyo, 2004
・XVIII Coloquio de Teoria de las Graficas, Combinatoria, y sus Aplicaciones, Agua Calientes,
 Mexico 2003
・Japan Conference on Discrete and Computational Geometry (JCDCG’2002),
 Tokyo, 2002
・Indonesia-Japan, Joint Conference in Combinatorial Geometry and Graph Theory, Bandung,
 Indonesia 2003
・Annual Meeting of the Mathematical Society of Thailand, Hatyai, Thailand 2002
・International Conference on Graph Theory and Discrete Geometry in Honor of Frank Harary,
 Manila, Philippines 2001
・The 9th International Congress on Mathematical Education (ICME), Makuhari, Japan 2000
・Japan Conference on Discrete and Computational Geometry (JCDCG2000), Tokyo, Japan
 2000
・Mathematics and Art, Brisbane, Australia 2000
・The 9th Quadrennial International Conference on Graph Theory, Combinatorics, Algorithms
 and Applications, Kalamazoo, Michigan, USA 2000


International Conferences Organized (After 2000)
・JCDCGG (18th Japan Conference on Discrete and Computational Geometry and Graphs),
 Kyoto, 2015
・JCDCGG (17th Japan Conference on Discrete and Computational Geometry and Graphs),
 Tokyo, 2014
・JCDCGG (16th Japan Conference on Discrete and Computational Geometry and Graphs),
 Tokyo, 2013
・Thai Japan Joint Conference on Computational Geometry and Graph Theory (TJJCCGG
 2012), Bangkok, Thailand, Dec, 2012.
・International Conference on Computational Geometry and Graph Theory (CGGA2010), Dalian
 Maritime University, China, 2010
・Japan Conference on Computational Geometry and Graphs (JCCGG 2009 at Kanazawa).
 JAIST, Kanazawa, 2009.
・China-Japan Joint Conference on Discrete Geometry, Combinatorics and Graph Theory,
 Tianjin/Xian, China 2005
・Japan Conference on Discrete and Computational Geometry (JCDCG2004), Tokyo, 2004
・Indonesia-Japan Joint Conference on Combinatorial Geometry and Graph Theory, Bandung,
 Indonesia 2003
・Japan Conference on Discrete and Computational Geometry (JCDCG2002), Tokyo, 2002
・International Conference on Graph Theory and Discrete Geometry in Honor of Frank Harary,
 Manila, Philippines 2001
・Japan Conference on Discrete and Computational Geometry (JCDCG2000), Tokyo, 2000