# Life-Cycle Oriented Risk Assessment Using a Monte Carlo Simulation
## 2 State of the Art
### Quality Management  
Quality is a concept that compares the characteristics of a product, process, or system against the initial requirements set out for it. This broad definition widens the range of objects to which quality can be assigned [15]. Quality is defined by ISO 9000 as: \"[...] the degree to which a set of inherent characteristics fulfils requirements [16].\" In production and industrial engineering, this concept turned into an applicable quantity of defects that should be recognizable, measurable, and controllable. The focus of a zero-defects strategy is therefore on prevention and avoidance of failures. As [PERSON] [17] emphasized in his 'total quality control', the responsibility for quality is with everyone involved in the creation and production processes, from top-level management to shop floor. This understanding plays a major role in a corporate environment and is highly affected by the company's culture.  
[PERSON] [18] assessed the existing definitions and identified five basic approaches: the transcendental, the product-based, the customer-based, the production-based and the value-based approach. Based on the findings of the analysis he derived eight dimensions of quality, which are applicable for every product: reliability, features, aesthetics, service, performance, conformance, durability, and perception. Often the sustainability is added as an additional term. [PERSON] and [PERSON] [15] define quality assurance as \"[...] all methods preparing and controlling the compliance of processes and products with predetermined quality standards\". Furthermore, \"quality assurance\" represents the monitoring of process outputs to avoid the procrastination of failures and to identify and reject defective parts. Historically, quality assurance can also be seen first as an antecedent and nowadays as the operational part of quality management\" [15]. This can be achieved with multiple methods of measurement and statistics in production. Nonetheless, comprehensive quality assurance can only be achieved by ensuring and gaining internal and external customer requirements and to assess products and processes against these requirements. Therefore, the ongoing change management of these requirements is paramount.  
[PERSON], et al. [19], provide a comprehensive overview of virtual quality gates in manufacturing systems. This method supports the reduction of the total cost of quality while ensuring high transparency about process-product relationships in production. To decrease the total cost of maintaining quality and reduce rework or scrap, it is necessary to consider the complete process chain instead of single and isolated processes. This can only be achieved by understanding the dynamics and interdependencies within the process chain. Furthermore, the \"context of product quality, transparency and understanding of process-product relationships, which describe interactions and the impact of the manufacturing processes on the resulting intermediate product features and vice versa, are of great importance\" [19]. The concept of quality gates is therefore to systematically divide the manufacturing chain into different quality-relevant decision points.