The thesis is based on the research work performed between the years 1995 and 2001 at the Work Science Laboratory of the Department of Process Engineering, University of Oulu. Part of the research was done at the Finnish Laboratory of Applied Ergonomics.
I am extremely grateful to my supervisor Professor Seppo Väyrynen. Without his encouragement and support during the years of research, this thesis would never have been completed.
I would also like to thank the other co-writers of the papers: Nina Nevala-Puranen, Ari Häikiö, Kari Kisko, Hannu Virokannas, Vesa Tornberg, Eeva Kangas, Jarkko Hyysalo, Anu Oikarinen and Ulla Hiltunen. I wish to thank my colleagues from the Work Science Laboratory, the Finnish Laboratory of Applied Ergonomics and also other collegues in Oulu University, with whom I have worked during these years, for the pleasant working atmosphere and for help in the organising and conducting the substudies needed for the papers. Thanks also to the subjects who have participated in the substudies.
I would like to thank Docent Kaija Leena Saarela and Docent Kari Häkkinen for reviewing the thesis and for their critical and constructive comments on the thesis. For the linguistic review of the English manuscript I wish to thank Sirkka-Liisa Leinonen.
The writing of the thesis summary was financially supported by the Finnish Work Environment Fund, during the substudies financial support was gained from the Academy of Finland, Tauno Tönning Foundation, the Work Science Laboratory, the Finnish Laboratory of Applied Ergonomics and the Ministry of Labor in Finland, all of which are gratefully acknowledged.
Finally, my warmest thanks are due to my husband Markku, my son Ville and my daughter Jenni. Their support has given me the power to accomplish this research work. I would also like to thank my parents, brother and sister and friends for their support during all these years.
Oulu, March 2001 Heli Kirvesoja