1. Normal Accidents: Living with High-Risk Technologies Minho Jeung Trinity Team 12/06/2005

2. Contents 1. Introduction 2. Normal Accident Theory 3. Three Mile Island 4. Policy Recommendations 5. Conclusion 2/11

3. Modern people manage to get along one way or others meeting with an accident. People forget accident immediately and adapt themselves the dangerous environment People do not have any solution to address the problem Tightly coupled technology system makes people not avoid an accident Accidents are neither abnormal nor deviatory. Accidents are normal events for complex system. 3/11 1. Introduction

4. The accidents caused by component failures The accidents are caused by interactive complexity in the presence of tight coupled system. Modern systems can tolerate the impact of the fault of a single component. Normal accidents are not caused by the failure of component but the interaction of components. 4/11 2. Normal Accident Theory This picture is referenced by Introduction Accidents Analysis, Yu-Hsing Huang, CSELAB, University of Linkoping

5. Tightly coupled interactions: These are represented to those that do not tolerate delay. They have invariant sequences and small slack. Loosely coupled interactions: These have the opposite characteristics. The interactions are linear or complex. The linear means simple system. The other is complex. Thus, Perrow made the following framework to classify systems according to these definitions. 5/11 2. Normal Accident Theory

6. Systemic elements led to major accidents, not the actions of the operators themselves Systemic elements led to major accidents, not the actions of the operators themselves The combination of interactive complexity and tight coupling of the high risk systems The combination of interactive complexity and tight coupling of the high risk systems 6/11 3. Three Mile Island This picture is referenced by http://www.libraries.psu.edu/tmi/images/tmi.jpg

7. 7/11 3. Three Mile Island This picture is referenced by http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/tmi-2.gif

8. Perrow made a set of policy recommendations, which are targeted at specific systems. The three policies are: abandon, restrict, tolerate and improve. Plotted various systems on the chart, and then draws curves to split them into three categories. 8/11 4. Policy Recommendations

9. 5. Conclusion Tightly coupled system can cause catastrophic accidents. Tightly coupled system can cause catastrophic accidents. The system is made loosed or the system has some redundancy. The system is made loosed or the system has some redundancy. 9/11 ► Lessons Learned

10. ► How we apply Normal Accident Theory to Studio? 10/11 5. Conclusion The VR engine can be used in various fields of industry It will be tightly coupled with the legacy system Design the system to have redundancy.

11. Thank you