The MTT assay is one of superior evaluation methods widely used to analyze the viability of metabolically active cell. It can be used to determine the percentage of viable sperm through measurement of the reduction of MTT granules at mitochondria in sperm tail. The purpose of this study is to determine the optimal condition of a simple and easy MTT assay to validate boar sperm viability and compare the accuracy of this test with microscopic examination. The MTT reduction rate for sperm viability were analyzed in microtiter plates (96 well) from 1 hr to 5 hr incubation periods at using spectrophotometer (microplate reader) at 550 nm wavelength. The remainder of semen sample was simultaneously examined to compare the correlation of accuracy between MTT assay and other sperm parameters. Those sperm parameters were included the motility, survival rates, membrane integrity, mitochondria activity and acrosome integrity. The OD values of MTT assay (MTT reduction rates) did not greatly change at 1 hr to 5 hr incubation periods in different proportion of live and freeze-killed sperms (dead sperm). The MTT reduction rates or survival rates were decreased according to the different concentration of live and dead sperm. The linear regression at 1 hr and 4 hr incubation periods in sperm MTT assay was y=291.55x-72.176 and y= 180.64x-44.569, respectively. There are high correlation between 1 hr and 4 hr incubation periods (p<0.001). The results of MTT assay and other sperm parameters has a positive correlation (p<0.01 or 0.05). The correlation coefficients for MTT assay was 0.88115 for motility, 0.89868 for survival rates, 0.91722 for membrane integrity and 0.77372 for acrosome integrity, respectively. In conclusion, the MTT assay can be used as a reliable and efficient evaluation method for boar sperm viability. It can be use practical means to evaluate the quality of boar sperm by a fast, inexpensive and easy method.

In this study, actual status of safety management for the objects of 173 university, government research institution, and corporate affiliated research center was carried out through questionnaires. For unexpected accident status according to kinds, scale, and types of laboratories, frequency analysis using cross analysis and multiple replies analysis was used. The result of this study is judged to be used for laboratory safety education prevention programs, laboratory environment improvement, investment or improvement of laboratories through the actual safety management status of laboratories such as vulnerable works for generation of unexpected sudden accidents according to kind, scale, and type of laboratories, period of occurrence, prevention education, necessity for preliminary test, and cause of laboratory accidents.

Recently, there are many research of musculoskeletal disorders in manufacturing industry because of increasing interest of that disorders, but the research is still lacking in the small business and service industry. So we researched relationship between working characteristics and subjective symptoms associated with musculoskeletal disorders by get information of 145 hairdresser about working hour, work record, position and working pattern. The results of this research show that there are many musculoskeletal disorders of hairdressers' neck, shoulder, arm, knee and also close relationship between working characteristics and subjective symptoms associated with musculoskeletal disorders. Besides, some parts of subjective symptoms have an effect on other parts of body. This information contributes to future reference and a precautionary measure about musculoskeletal disorders for hairdressers.