Human-machine interface technology or hardware ergonomics. This primarily concerns the study of human physical and perceptual characteristics and the application of these data to the design of controls, displays, seating, workstations and related workspace arrangements [7] .

A study of the wood industry in South Africa was conducted in 1994 among 300 foresters in the industry due to inappropriate Leg protectors. An average of ten injuries per day was occurring with an average sick leave of five days per injury. The ergonomic redesign of the instrument (leg protector) showed that no injury or damage has occurred during the day for the foresters and this design lead to annual savings of $ 4 million in the company [8] .

In another study in which the Microsoft conducted in 2004, showed that the use of ergonomic tools through the use of computers has led to a 10 percent reduction in injuries from repetitive movements (RSI) In the amount of $ 700,000 in annual savings [9] . In addition, LEE conducted a study in 2001 at a Korean electric appliance company, which focused on machinery and tools, which were used by workers. At first stage ergonomic risk assessment was done ,then using  simple and low cost ergonomic methods resulted in increased productivity(10% - 30%)and cost savings (approximately $17.01 million). Further, the number of musculoskeletal problems was significantly reduced [3] . The following (Figure 1) shows hardware ergonomics intervention.

According to the above researches, we can conclude on how hardware ergonomics can have a tremendous impact on the quality.

Human-environment interface technology or environmental ergonomics. It concerns the effects of various physical environmental factors, such as illumination, heat, cold, noise and vibration, on human performance, and the application of these data to the design of physical environments for people [7] .

In a number of papers Sanders and McCormick on the effects of noise, vibration and light on human error and bad performance did some research [10] .

In another study Griffin, vibrations at frequencies above than20 Hz, shown that these vibrations can lead to neurological–muscle disorders and will eventually lead to human errors [11] .

Chemicals can cause different effects on performance, for example, organic solvents may lead to changes in the central nervous system which results in the disruption of individual decisions and activities. That was showed by Stollery [12] .

According to the above studies, it is clear that the lack of attention to environment ergonomic can impact on employee performance and, ultimately, leads to a decline in the quality, this is shown graphically by Eklund [1] . As follows (Figure 2).

Human-software interface technology, which is the central focus of cognitive ergonomics. It deals with the way people think, conceptualize, and process information, and the application of these data to software design [7] .

Several studies that have done by Wagenaar, Larson and Wallace Showed that cognitive failure have a large impact on job performance and safety [13] -[15] . In another study, Treat and colleagues concluded that more than 70 percent of accidents are due to human errors [16] . Given that Mr. Allahyari have expressed in his article that cognitive errors can be used as an indicator of information processing capability, which can affect on the performance and activities [17] . So what can be concluded is, the impact of cognitive ergonomics on the quality is obvious.

In another research project in which an Ameritech company was done in America, they redesigned the CRT displays used in the company according to the principles of cognitive ergonomics (the way people think, conceptualize, and process information).the results showed a 600-ms reduction in average call operating time. This reduction in time will lead to savings of $2.94 million annually [18] . The following (Figure 3) shows CRT before and after the changes.

Human-job interface technology or work design ergonomics. It concerns the design of jobs to ensure proper workload and characteristics such as task variety or having different meaningful things to do in one’s work, identity or sense of job wholeness, significance or perceived job meaningfulness, autonomy or control over one's work, and feedback or knowledge of results [7] .

In a study conducted in wood industry in South African, redesigning the Tractor-trailer workstation will result in improved visibility and comfort of operator. The extent of the damage to machine components dropped. This changes in the workstation eventually lead to annual savings $ 65,000 [8] . In another study on the Handling & Stock Keeping system, the company redesigned a workstation ergonomically. The redesign reduced the noise level in the area from 96 db to 78 db, increased production by 10%, dropped rejection from 2.5% to 1%, and paid back the redesign and development costs in approximately 18 months [8] .

At the end of this section, another study is discussed which was done by Choobineh and colleagues in Iranian

Hand-Woven carpet Industry about workstation design. 1439 randomly selected weavers participated in this study. The results showed that prevalence rates of musculoskeletal disorders were high. Finally, a review of the decision was taken to redesign their workstation. After making changes, weavers were questioned on this point, 70 percent said they are very pleased with the new conditions and have better comfort during work with better quality [19] . Before (Figures 4 and 5) and after images of the workstation is shown.

Human-organization interface technology or macro ergonomics. It concerns the interfacing of employees with the over-all organizational design of the work system so as to most effectively utilize both the personnel and technology employed in the system in responding to the organization’s external environment [7] .

Henrick proposed a macro ergonomics model that could be applied to the prevention of occupational injuries [20] . In another paper Henrick has spoken about importance of the macro ergonomics and its impact on productivity [21] . Is determined according to both studies, how macro ergonomics impact on the quality of the work.

In another study Keliner showed, Macro ergonomics has been demonstrated to improve work system performance throughout sub-system areas, including productivity, quality, safety and health, quality of work life, user satisfaction, etc. [22] .

Another study was conducted by Habibi and colleagues, macro ergonomic conditions and its relationship with job satisfaction of employees in a company were analyzed. After reviewing the results of the statistical analysis, showed that there is a direct relationship between job satisfaction and general aspects of macro ergonomics. (r = 0.638 and Pvalue = 0.001) [23] . At the end of this section, Roonay and colleagues study is also discussed. The study was done in L.L. Bean Company, known internationally for the high quality of its clothing products. They have reported on the use of macro ergonomics as an approach and methodology for introducing total quality management (TQM). In two years of study and using macroergonomics methods, the accident rate dropped 70% as well as significantly increased levels of job satisfaction [24] .

Above studies showed how easily, the macro ergonomics principles could affect the quality of work.