This study aims to empirically investigate effects of motion repetition and external load according to joint motion on discomfort through an experiment. Eighteen college students (female: 9; male: 9) participated in an experiment measuring perceived discomfort using the Borg CR10. Joint(wrist, elbow, shoulder and trunk) motion, its repetition and external load were adopted as independent variables. The results showed that all three independent variables were statistically significant on discomfort. Participants’ sex also significantly affected discomfort obtained in the experiment. While the interactions of joint motion and repetition, and joint motion and external load were not significant at α = 0.05, that of motion repetition and external load was significant. Based on the experimental results, four regression equations by the joints involved were presented, which could be used as a tool for evaluating postural loads by the joints. It may be postulated that based on the results of this study, scoring systems of RULA and REBA, and those of OWAS and REBA underestimates effects of motion repetition and external load, respectively. It is expected that the results of this study will be used as a basic data for developing an observational method properly reflecting the effects of motion repetition and external load.

This study aims to review observational methods for assessing postural loads such as OWAS, RULA and REBA, and to compare them, based on the literature survey. The literature was searched through academic database of ScienceDirect using the key words of observational methods, OWAS, RULA and REBA. The results exhibited that of the thee methods, RULA was cited in the literature and applied to manufacturing industries the most frequently. Although it has been known that RULA is appropriate for assessing upper body postures, it has been applied to healthcare and social work activities, agriculture, forestry, fishing, construction, mining and quarrying, which require unstable lower limb postures. The countries where more number of relevant studies have been carried out were USA, India, Brazil, UK, etc. It was recommended that of the three techniques, RULA may be better for assessing postural loads, because it evaluated postural loads more highly, irrespective of industry, work type and lower limb postures, and its assessment results had higher agreement rate with experts’ assessments than those of OWAS and REBA. It is expected that the results of this study will be used as a guideline for selecting an appropriate observational method.

This study aims to investigate laws and standards(including technical guidelines) related to safety criteria for 22 kitchen machines frequently used in commercial kitchens. The study was based on literature survey, interviews with charge persons in kitchen machines manufacturing companies, cafeteria providing group meals and relevant association, and web surfing. The results showed that there are two types of safety criteria such as legally forced ones by laws and optional ones by national industrial standards or technical guidelines. High pressure safety control act, safety control and business of liquefied petroleum gas act and city gas business act prescribed gas use apparatus safety criteria, rational energy utilization act did those of pressure vessel such large rotary caldron, industrial health and safety act did those of food processing machinery, and electrical appliances safety control act did those of electrical kitchen appliances. Compulsory or optional standards or guidelines related to safety criteria for kitchen machines were presented by 22 kitchen machines. Safety devices shown in the laws, standards and guidelines were also summarized by kitchen machines and their risk factors.

The purpose of this study is to investigate EU, UK and USA’s laws and standards related to safety criteria for commercial kitchen machines. The study was based on literature survey and web surfing. The results revealed that EU has relevant directives by kitchen machines and harmonized standards according to the directives. The directives and harmonized standards are translated into the laws and standards of EU member countries, respectively. The kitchen facility relevant legal systems of UK and USA do not prescribe the safety devices or measures, but only the basic health and safety requirements. The requirements were forcefully implemented through the certificate systems such as CE(Confommite European), UL(Underwriters Laboratories), etc. Only products with CE, UL or NRTL(ationally Recognized Testing Laboratory) certificate marking can be placed on the market of EU and USA, or put into service. For achieving the certificates, all requirements regulated in the relevant standards should be met. The standards of UK and USA were presented by kitchen machines or by standards themselves, respectively. Safety devices required by the standards were also summarized by kitchen machines and their risk factors.

This study aims to investigate test-retest reliability or reproducibility of the paper-pencil test for investigating stereotypes of seven principal controls of passenger cars. The controls include wiper, head light, high beam, door window, ignition key, door key and door lock. Sixty two college-aged students participated in the paper-pencil tests and the tests were conducted twice with an in-between period of 4 weeks. The results showed that the stereotypes of motion-directions for the seven controls by the two paper-pencil tests were the same, and that the percentage agreements between two tests by subjects were ranged from 60.0% to 80.6%. There was a weak linear relationship between averaged rates of responses for the stereotypes of motion-directions for the seven controls and percentage agreements by subjects. Based on these results, it is concluded that the paper-pencil test collects reliable or reproducible data on the stereotypes of motion-directions for passenger cars’ controls within four weeks.

The purposes of this study are to survey stereotypes of control-display relationships for seven principal controls in passenger cars using the paper-pencil and hardware tests, and to examine stereotype strength of the paper-pencil test through comparing the stereotypes for the controls derived by the two methods. Ninety two and 60 college-aged students participated in the paper-pencil test and the real car simulation of the hardware test, respectively. There are dominant motion-directions for all controls in the paper-pencil test, while in the hardware test, there are dominant motion-directions for six controls including head light, high beam, door window, ignition key, door key and door lock controls. The stereotypes of motion-directions for six controls obtained by the paper-pencil test were the same as or similar to those by the hardware test. It was inferred from this that the congruence of the stereotypes by the two methods might be attributed to two simple motion-direction principles of 'clockwise for increase' and 'upward for increase.' Although it is known that the hardware test would be best for obtaining accurate stereotypes between controls and displays, this study implies that if the paper-pencil test is well designed, the paper-pencil test can produce the same results as the hardware test at low cost and without consuming time.

The aims of this study are to investigate stereotypes of motion-direction and real motion-directions for seven principal controls in passenger cars, and to compare the stereotypes and real motion-directions for the controls. The stereotypes were obtained by using questionnaire survey, in which 385 subjects participated. The real motion-direction data were gathered for 64 passenger cars including RVs and SUVs. The results showed that while there are dominant motion-directions for head light, door key and door lock controls, dominant motion-directions are not found for other controls investigated in this study. The stereotypes of motion-directions for seven controls obtained in this study were much different from those of the real data. Furthermore, the stereotypes for wiper, head light and high beam controls based on the questionnaire survey were opposite to the real motion-directions.

In this study, the representative hand shapes for the adult Koreans were analyzed by factor analysis and cluster analyses. The analyses were conducted on the anthropometric data of 58 hand dimensions from 325 subjects having nonhomogeneous demographics. Maximum hand circumference, first phalanx length of index finger, and ratio between the two measures were the independent variables for the cluster analyses. The results of the study showed that Korean hand shapes can be divided into 2 clusters irrespective of their size for each of the male and female group. There were slight differences in component ratio of hand shapes with respect to the occupation and the age, but their differences were not statistically significant. The representative Korean hand shapes and their anthrpometric dimensions could be used to design and establish proper sizing system for various hand operating devices.

This paper was proposed to show the comprehensive review of laws and regulations on the musculoskeletal disorders (MSDs) that are being established and carried out in various countries. Ten countries including USA, Canada, Australia, Japan, and 6 European countries which were regarded as the leaders in the prevention of MSDs were selected for review. Comparative analysis were performed on the laws, regulations, and guidelines of MSDs among different countries. The purpose of this study was to investigate the status of the various efforts of the advanced countries concerning on preventing MSDs and suggest the improvement factors that might be introducible to Korean policies. Some recommendations were made to improve the appropriateness and efficiency of our MSDs prevention policies based on the comprehensive review and comparative analysis. It is expected that the results of this study would be used as valuable information when revising relevant legal system.