• Journal of Preventive Medicine and Public Health
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• v.43 no.3
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• pp.205-212
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• 2010

Objectives: The prevalence of work-related musculoskeletal symptoms (WMS) among Korean dairy farmers has not been investigated. The purpose of this study was to assess the prevalence of WMS and to evaluate the relationship between WMS and risk factors. Methods: Self-developed questionnaires including the questionnaire developed by the Korean Occupational Safety and Health agency (KOSHA) were used to investigate WMS among dairy farmers in Gyeonggi Province, Korea. We informed selected dairy farmers about the study and sent the questionnaires by registered mail. They visited a public health center nearby or a branch of public health center on the appointed date and skillful researchers identified or conducted the questionnaires by interview. We analyzed 598 (32.8%) of the 1824 dairy farmers. Multiple logistic regression was implemented to estimate the odds ratios of risk factors. Results: The mean age of the respondents was $50.4{\pm}8.7$ years and the proportion of males was 63.0%. The prevalence of WMS at any site was 33.3%. The prevalence of neck WMS was 2.2%, shoulders 10.0%, arms/elbows 5.0%, hands/wrists/fingers 4.2%, low back 11.5%, and legs/feet 11.7%. The adjusted odds ratio of low back WMS for milking 4 or more hours per day was 4.231 (95% Cl = 1.124 - 15.932) and statistically significant. Low back WMS (2.827, 95% Cl = 1.545 - 5.174) was significantly decreased by education. Conclusions: Low back WMS increased with milking hours and milking 4 or more hours per day was significantly associated with low back WMS. Low back WMS was significantly reduced with education. We hope that there will be increased attention about WMS in dairy farmers and the subject of future investigations.

• International Journal of Safety
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• v.6 no.2
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• pp.1-7
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• 2007

In this study mechanical strength of A53B carbon steel was analyzed using several types of test specimens directly machined from oil recycling pipe experienced a failure due to hydrogen attack in chemical plants. High temperature hydrogen attack (HTHA) is the damage process of grain boundary facets due to a chemical reaction of carbides with hydrogen, thus forming cavities with high pressure methane gas. Driven by the methane gas pressure, the cavities grow on grain boundaries forming intergranular micro cracks. Microscopic optical examination, tensile test, Charpy impact test, hardness measurement, and small punch (SP) test were performed. Carbon content of the hydrogen attacked specimens was dramatically reduced compared with that of standard specification of A53B. Traces of decarburization and micro-cracks were observed by optical and scanning electron microscopy. Charpy impact energy in hydrogen attacked part of the pipe exhibited very low values due to the decarburization and micro fissure formation by HTHA, on the other hand, data tested from the sound part of the pipe showed high and scattered impact energy. Maximum reaction forces and ductility in SP test were decreased at hydrogen attacked part of the pipe compared with sound part of the pipe. Finite element analyses for SP test were performed to estimate tensile properties for untested part of the pipe in tensile test. And fracture toughness was calculated using an equivalent strain concept with SP test and finite element analysis results.

• Journal of the Korean Society of Safety
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• v.29 no.2
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• pp.24-30
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• 2014

There have been controversies over whether explosion hazardous area(EHA) should be classified for facilities which use lighter-than-air gases such as city gas, hydrogen and ammonia. Two view points are confronting each other: an economic piont of view that these gases are lighter than air and disperse rapidly, hence do not form EHA upon release into the atmosphere, and a safety point of view that they are also inflammable gases, hence can form EHA although the extent is limited compared to heavy gases. But various standards such as KS, IEC, API, NFPA do not exclude light gases when classifying EHA and present examples of EHA for light gas facilities. This study calculates EHA using the hypothetical volume in the IEC code where the hole sizes required for the calculation were selected according to various nominal pipe sizes in such a way to conform to the EHA data in the API code and HSL. Then, 25 leakage scenarios were suggested for 5 different pipe sizes and 5 operating pressures that cover typical operating conditions of light gas facilities. The EHA for the minimum leakage scenario(25 mm pipe, 0.01MPa pressure) was found to correspond to a hypothetical volume larger than 0.1 $m^3$(medium-level ventilation). This confirms the validity of classifying EHA for facilities using lighter-than-air gases. Finally, a computer program called HACPL was developed for easy use by light gas facilities that classifies EHA according to operating pressures and pipe sizes.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.858-868
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• 2017

Korea's shipbuilding industry has led the world in the technical area over the last century. Despite this commendable performance, around 2,000 workers experience accidents almost every year with 40 being killed. This raises a question of whether the safety level of our shipbuilding industry, in particular the safety of workers, is actually at the world-class level. Accordingly, this research has analyzed several types of safety training currently provided in the field through investigating statistical data of serious accidents occurring from 2006 to 2015 in the domestic shipbuilding industry, analyzing its occurrence and causes, and conducting a survey targeting employees in the shipbuilding industry. Based on this, it has investigated problems of safety training in the shipbuilding industry and suggested improvements. First, it is essential to create a standard system for safety training in the shipbuilding industry to address problems of different kinds and levels of safety training provided by each shipyard and low quality of training, and operate more organized and systemized training. Second, safety training curriculum specializing in the shipbuilding industry should continue to be developed and standardized based on a standard system for safe training to prevent serious accidents and improve safety awareness of workers. Lastly, both employers and employees should actively provide and participate in safety training to secure safety of workers through preventing serious accidents and ultimately create safety-first culture in workplace.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.403-412
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• 2012

Purpose: This study is conducted to evaluate the job stressors for dental technicians in Ulsan city. Methods: The Korean standard job stressors assessment tool developed by Korea Occupational Safety and Health Agency (KOSHA) was used to compare the survey result with Korean reference value. The questionnaire on the social, demographic and job characteristics of dental technicians was also used to find the factors affecting to job stressors by using multiple linear regression analysis. Results: A total of 155 questionnaire was collected from 2010 to 2011. Among the eight fields of stressors, the physical environment (men 50.0, women; 58.3) and job demands (men 57.1, women 57.1) were higher than the median value of the Korean Workers. By multiple linear regression analysis, the significant factors to the physical environment were the satisfaction degree of indoor odor, number of employee, duty and working hours. In terms of the job demand, duty, working hours, age, and the satisfaction to the efficiency of space utilization were significantly associated to the score of job demand. Conclusion: Based on these results, it is necessary to manage appropriate workload, control indoor odor and design an efficient work space for prevention of job stress of dental technicians.

• Journal of the Korean Society of Safety
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• v.18 no.4
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• pp.169-175
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• 2003

In this paper, and estimation method for estimating the states of underwater vehicle systems with external unknown disturbance is proposed. First, the dynamics of underwater vehicle are induced by Taylor series expansion in the vertical plane and horizontal plane, respectively. For constructing the system model, the external efforts, i.e., the sea surface disturbances, the current, wave and etc., are regarded as external unknown disturbances. Thus the disturbance is added as external input into state-space form of underwater vehicle system. To estimate the state of systems with unknown disturbance, a disturbance observer which does not effected the external unknown input is proposed, and the existence condition for the observer is given. Finally, the effectiveness of the proposed disturbance observer for robust control of underwater vehicle systems is verified by using numerical simulation.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.32-38
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• 2023

In a chemical plant, while supplying corrosive fluid to a storage tank with a pump, an accident occurred where the corrosive fluid leaked through the upper exhaust vent because the level indicator was not accurately determined. There are various causes of leakage accidents, but we focused on the sticking of the level indicator of the level gauge, which is the direct cause. As a result of the analysis, the level indicator used in the workplace where the accident occurred was randomly replaced, and in the summer when the accident occurred, the tubular type level gauge was found to be more likely to stick than other types because thermal expansion easily occurs. In addition, there were difficulties in reviewing the proper installation because the installation standards for measuring instruments installed in storage tanks were not clear in Korea. Therefore, in this study, based on accident cases and overseas standards, we are going to find out about precautions when installing storage tank instrumentation.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.343-347
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• 2011

Precise traveling and tillage operation using an autonomous tractor is difficult with the data from the Geographic Information System(GIS) because it does not include the data of the width and inclination of the field to work. The minimum turing radius of the tractor could be different from the value presented by the tractor maker due to the moisture content of the field soil or operators' skill. Two programs were developed to process data obtained with the tillage path measuring system: one for recognizing coordinates of the 4 field corners, and the other for recognizing the minimum turning radius of the tractor.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.18-25
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• 2013

It may occur health hazards or death by suffocation or acute poisoning in case of oxygen deficiency in ambient or exposure to harmful gas. As a part of accident prevention, we studied the change of activity and lethal dose by changing the concentration of several hazardous gas with inhalation exposure chamber and laboratory animals. We investigated the lethality and motility change during either the 4 hrs whole body exposure to oxygen, nitrogen, toluene, $H_2S$, CO and 48 recovery. As results, it is estimated that 5% oxygen concentration as lethal concentration and 5.5% as $LC_{50}$ (rat, 4 hrs) with statistics for dose-response. The results of lethality in oxygen deficient condition (approximately 6%), the lethalities were 40%, 20% with 20 ppm $H_2S$, 600 ppm CO respectively, and was not increased the lethality with 8% CO. Thus, it was confirmed that the $H_2S$, CO had influence to lethal dose, while toluene had low fluence.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.1
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• pp.36-44
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• 2005

A push pull hood system is frequently applied to control contaminants evaporated from an open surface tank in recent years. Efficiency of push pull hood system is affected by various parameters, such as cross draft, vessel shapes, size of tanks surface, liquid temperature, and so on. Among these, velocity of cross draft might be one of the most influencing factor for determining the ventilation efficiency. To take account of the effect of cross draft velocities over 0.38m/s, a flow adjustment of ${\pm}$20% should be considered into the push and +20% into the pull flow system Although there are many studies about the efficiency evaluation of push pull hood system based on CFDs(Computational Fluid Dynamics) and experiments, there have been no reports regarding the influence of velocities and direction of cross-draft on push-pull hood efficiency. This study was conducted to investigate the influence of cross draft direction and velocities on the capture efficiency of the push-pull ventilation system. Smoke visualization method was used along with mock-up of push-pull hood systems to verify the ventilation efficiency by experiments. When the cross-draft blew from the same origins of the push flows, the efficiency of the system was in it's high value, but it was decreased significantly when the cross-draft came from the opposite side of push flows Moreover, the efficiency of the system dramatically decreased when the cross-draft of open surface tank was faster than 0.4m/s.