1. Poster Chairman of the VS-Games 2011 Conference, Athens, Greece, May 2011

2. General Chairman of the ACM ARTEMIS Workshop in Conjunction with ACM Multimedia, Florence, Italy, October 2010

3. General Chairman of the ACM EVENTANALYSIS Workshop in Conjunction with ACM Petra 2010, Samos, Greece, 2010

4.  2010 Technical Program Committee Member International Conference on Applied Computing, Timisoara, Romania

5. 2010 Technical Program Committee Member IASTED International Conference on Robotics and Applications, Cambridge, Boston, MA, USA.

 6.  2009: Technical Program Committe EURASIP, European Signal Processing Conference, EUSIPCO 2010, Aalborg, Denmark.

 7. 2009: General Chairman of the ACM Workshop in Conjunction with ACM PETRA Pervasive Technologies Related to Assistive Environment,” EVENTANALYSIS2009, Multimedia Event Analysis for Assistive Environments

 8.   2009: General Chairman of the ICST GRIDNETS, 7-9 Sept. Athens Greece.

 9.   2009: Technical Program Committee Member of the Workshop on Artificial Intelligence Approaches for Biometric Template Creation and Multibiometrics Fusion (ArtIBio), 23-25 April, Thessaloniki, 2009.

10.    2009: Technical Program Committee Member IASTED International Conference on Robotics and Applications, Cambridge, Boston, MA, USA.

11.  2009 Technical Program Committee Member Intenational Conference on Applied Computing, Rome, Italy.

12.  2009: Special Session Chairman in the ΙΕΕΕ International Conference on Systems, Signals and Image Processing with title "Computer Vision Algorithms using Intelligent Agents", Chalkida, Greece

13.  2009: Technical Program Committe EURASIP, European Signal Processing Conference, EUSIPCO 2009, Glasgow, Scotland.

14.  2009: Special Session Organizer in the International Conference on Artificial Neural Networks (ICANN) with title "Intelligent Tools and Methods for Multimedia Annotation", Limassol Cyprus 2009

13.  2008: General Chairman of the ACM AREA ("Analysis and Retrieval of Events/Actions and Workflows in Video Streams”) workshop in Conjunction with ACM Multimedia, Vancouver, Canada,

14. 2008: Special Session Organizer of the 10th WSEAS International Conference on Mathematical Methods, Computational Techniques and Intelligent Systems (MAMECTIS '08) with title "Advanced Annotation Tools and Methods", Corfu Greece

15.  2008: Technical Program Committe EURASIP, European Signal Processing Conference, EUSIPCO 2008, Lausanne, Switzerland.

16.  2008: Technical Program Committe International Conference on Pattern Recognition, Orlando, USA

17.  2007: Technical Program Committe European Signal Procesisng Conference, Poznan, EUSIPCO 2007, Poland.

18.  2007: Technical Program Committe IASTED International Conference on Robotics and Applications, Wuerzburg, Germany.

19.  2006: Technical Program Committe "Robotics & Applications", August, Honolulu, Hawaii, USA, 2004.

20.  2006: Special Session Organiser, International Conference on Artificial Neural Networks (ICANN), “Bridging the semantic gap in Multimedia: machine learning approaches” 2006 Athens, Greece

21.  2005: Technical Program Committe, "Robotics & Applications", Cambridge, Boston, MA, USA, 2005.

22.  2004: Technical Program Committe «ΕURASIP, European Signal Processing Conference (EUSIPCO)», Vienna, Austria, September.

23.  2004: Special Session Organiser "Content Understanding & Knowledge Modelling in Multimedia Databases" EURASIP, European Signal Processing Conference (EUSIPCO), Vienna, Austria, September.

24.  2004: Technical Program Committe "Robotics & Applications", August, Honolulu, Hawaii, USA, 2004.

22.  2003: Technical Program Committe, "Robotics & Applications", Saltsburg, Austria

23.  2001, Technical Chairman of "International conference on Very Low Bit Rate Video Coding, VLBV" Αθήνα, Οκτώβριος.

24.  1997: Workshop on Applications and Perspectives of Neural Networks Technology in Greece and the Broader Balkan Area" Athens, February 1997.

25.  1999: Technical Assistance "ΙΕΕΕ International Conference on Computer Vision ICCV’99", Corfou, 1999 Greece