• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.741-747
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• 2022

Fatigue lowers an individual's ability and makes it difficult to perform work. As fatigue accumulates, concentration decreases and thus the possibility of causing a safety accident increases. Awareness of fatigue is subjective, but it is necessary to quantitatively measure the level of fatigue in the actual field. In previous studies, it was proposed to measure the level of fatigue by expert judgment by adding objective indicators such as bio-signal analysis to subjective evaluations such as multidisciplinary fatigue scales. However this method is difficult to evaluate fatigue in real time in daily life. This paper is a study on the fatigue classification model that determines the fatigue level of workers in real time using speech data recorded in the field. Machine learning models such as logistic classification, support vector machine, and random forest are trained using speech data collected in the field. The performance evaluation showed good performance with accuracy of 0.677 to 0.758, of which logistic classification showed the best performance. From the experimental results, it can be seen that it is possible to classify the fatigue level using speech signals.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.750-754
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• 2014

Quantitative risk analysis has been performed for a pervaporation process for production of high test peroxide. Potential main accidents are explosion and fire caused by a decomposition reaction. As the target process has a laboratory scale, the consequence is considered to belong to Category 3. An event tree has been developed as a model for occurrence of a decomposition reaction in the target process. The probability functions of the accident causes have been established based on the frequency data of similar events. Using the constructed model, the failure rate has been calculated. The result indicates that additional safety devices are required in order to achieve an acceptable risk level, i.e. an accident frequency less than $10^{-4}/yr$. Therefore, a layer of protection analysis has been applied. As a result, it is suggested to introduce inherently safer design to avoid catalytic reaction, a safety instrumented function to prevent overheating, and a relief system that prevents explosion even if a decomposition reaction occurs. The proposed method is expected to contribute to developing safety management systems for various chemical processes including concentration of hydrogen peroxide.

• Journal of the Korean Institute of Gas
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• v.17 no.2
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• pp.28-35
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• 2013

The number of large and complex buildings is growing and they are usually concentrated in metropolitan cities. There is a possibility in such buildings that a small accident can expand to a massive disaster since their scale and complexity. To deal with this issue, a research on gas sensors which can detect multiple gases and early-warning systems has been conducted. Proper criteria or standards are necessary for effective application and operation of such sensor-based disaster monitoring system. In this study, we have proposed the alarm criteria of concentration of hazardous gases for the detection and the alarm release. For each alarm level, systematic disaster response plans consist of responsive actions and information delivery have been prepared. These disaster monitoring criteria can help the detection of hazardous gas-related disaster in the early stage of accident and the provision of appropriate emergency responses.

• Safety and Health at Work
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• v.11 no.1
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• pp.61-70
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• 2020

Background: This study aims to assess whether the TSI PortaCount (Model 8020) is a measuring instrument comparable with the flame photometer. This would provide an indication for the suitability of the PortaCount for determining the workplace protection factor for particulate filtering facepiece respirators. Methods: The PortaCount (with and without the N95-Companion^TM) was compared with a stationary flame photometer from Moores (Wallisdown) Ltd (Type 1100), which is a measuring instrument used in the procedure for determining the total inward leakage of the particulate filtering facepiece respirator in the European Standard. Penetration levels of sodium chloride aerosol through sample respirators of two brands (A and B) were determined by the two measuring systems under laboratory conditions. For each brand, thirty-six measurements were conducted. The samples were split into groups according to their protection level, conditioning before testing, and aerosol concentration. The relationship between the gauged data from two measuring systems was determined. In addition, the particle size distribution inside the respirator and outside the respirator was documented. Linear regression analysis was used to calculate the association between the PortaCount (with and without the N95-Companion^TM) and the flame photometer. Results: A linear relationship was found between the raw data scaled with the PortaCount (without N95-Companion^TM) and the data detected by the flame photometer (R² = 0.9704) under all test conditions. The distribution of particle size was found to be the same inside and outside the respirator in almost all cases. Conclusion: Based on the obtained data, the PortaCount may be applicable for the determination of workplace protection factor.

• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.42-47
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• 2011

Going underwater is supposed to begin with the history of human beings. At first it was confined to relatively shallow level, less than several meters by holding breath. Recently, deep level diving has been necessary for such purpose as construction, maritime salvage, military operations, research and sports by using SCUBA(self-contained underwater breathing apparatus) equipment. As one goes down into water, the pressure on the diver is increased due to water pressure with depth, usually 1 atm for each 10 m water level. In deep water, mixed gas or nitrox(EAN, enriched air nitrox) could be applied for the divers lest they should get disease due to high pressure. Of these, the former is usually composed of oxygen and inert gas like helium or hydrogen, the latter contains higher oxygen content than that in normal air in which the oxygen concentration is designated by the character "EAN" followed by vol. % of oxygen, for example, "EAN 40" contains 40% of oxygen. In this case, a victim was found at the 39 m below the sea surface breathing air and nitrox in cylinder wrongly marked as EAN 36, which was analyzed to contain 63% of oxygen by GC/TCD. The cause of death could not be exactly related with the oxygen content in the nitrox cylinder, because the accurate depth for the victim to dive was not known, even though the victim was just found at the depth of 39 m. However, the wrongly marked nitrox could be believed to be the main cause of the death at the depth unless there happened any other accident except that during diving.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.6
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• pp.746-753
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• 2012

ROK military helicopters are frequently exposed to the hazard situations due to the characteristic of operation. Especially, helicopter accident may lead to critical damage of human and structure. Accordingly, pilots have to train the autorotation procedures and learn the skill to prevent hard landing. In this paper, the behavior of skid gear subject to the helicopter autorotation was conducted by using numerical method. The computer simulation approach by using finite element method was employed to accomplish this goal. Additionally, the behavior of skid gear was evaluated for the different landing conditions. In conclusion, the maximum stress concentration was occurred at the attached area of skid cross-tube to the fuselage. Also, it was revealed that the most proper attitude was level landing to prevent hard landing.

• Journal of the Korean Institute of Gas
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• v.7 no.4 s.21
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• pp.14-19
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• 2003

Generally the accident by gas explosion in the working place is occurred at the condition of non-uniform mixture rather than uniform one. This study could predict the explosion phenomenon of non-uniform mixture with model explosion chamber which realize various practical conditions As a result, the mixing level of gas in the chamber depends on discharge area and velocity when there is gas discharge in certain space. In addition, as non-uniform increases, explosion pressure and its increasing rate decrease. However, firing risk after the explosion flame by infrared heat increase due to the increase of residence time of flame.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.3
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• pp.76-85
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• 2022

Work situational awareness test (WSAT) has been utilized to estimate the fatigue risk of workers who worked with time pressure or latent accident risks at their work environment. Thus researchers decided to use WSAT to estimate fatigue risk of cabin crews of an airline in Korea and to analyze empirically how such risk might have an effect on cabin crew's safety behavior. This was because there had not been enough research on accessing cabin crews' fatigue and analyzing its risk for the flight safety. In addition, the mediation effect of cabin crew's planning was also analyzed through Sobel-test by researchers among external factors such as lack of concentration, attention deficit, distraction and safety behavior. According to empirical analysis, it was found attention deficit and distraction of cabin crews due to fatigue during the flight had a significant negative effect on their planning. Planning was also proven to have mediation effect to cabin crew's safety behavior.

• International Journal of Advanced Culture Technology
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• v.11 no.3
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• pp.346-357
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• 2023

The purpose of this study is to suggest improvement plans for prevention regulations by reflecting the toxicity, fire and explosion effects of hazardous materials factories and surrounding areas using an off-site consequence assessment program. Regarding the effects of the hydrogen cyanide leak accident, which is the 1st petroleum of the 4th class flammable liquid, Areal Locations of Hazardous Atmospheres (ALOHA) program was used to compare and analyze the extent of damage effects for toxicity, overpressure, and radiation. As a result, the toxicity was analyzed to exceed 5km in the area with Acute exposure guideline level (AEGL)-2 concentration or higher, the overpressure was 103m in the range of 1 psi or more, and the radiant heat was analyzed to be 724m in the range of 2kw/m² or more. Toxicity and radiation affected the area outside the hazardous material storage area, but the overpressure was limited to the inside of the hazardous material storage area. Therefore, we propose to improve the safety management of hazardous materials by conducting a risk assessment for hazardous materials and reflecting the results in internal and external emergency response plans to prepare prevention regulations.

• Journal of Environmental Health Sciences
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• v.34 no.4
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• pp.279-284
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• 2008

This paper aims to provide basic data for work environment control, prevention of worker exposure to asbestos and improvement of air quality to protect workers ‘health after measuring the level of airborne asbestos and workers' exposure in a shipbuilding repair businesses. For this study, a total of 27 samples were collected from 27 workers who had been exposed to asbestos during engine, piping, boiler and other manufacturing processes in 'A' Shipbuilding Repair Company in Gyeongnam. This research was conducted from Oct. 1 to 30, 2007 and had the following results: The target group (27 workers) consisted of all men with an average age of 35.9 years and 6.6 years of work on average. Among them, fifteen 15 (55.6%) were smokers. In terms of their duties at work, there were 12 plumbing repair engineers (44.4%), 8 boiler repair engineers (29.6%) and 7 engine engineers (25.9%). The geometric mean concentration of airborne asbestos was 0.004 f/cc. A total of 4 samples exceeded the exposure limit. In particular, three exceeded the legal limit by more than double, which means that some workers have been highly exposed to asbestos. In terms of the concentration of asbestos fibres by work process, plumbing repair was the highest (0.0071 f/cc($0.001{\sim}0.57\;f/cc$)) while boiler was the lowest (0.0015 f/cc($0.001{\sim}0.007\;f/cc$)). Based on this study, proper action needs to be taken as soon as possible to protect workers from the threat of asbestos.