• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.224-231
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• 2009

The improvement of cold start capability is one of the most challenging tasks to be solved for commercialization of fuel cell vehicle. In this study, cold start test and ice blocking test(IBT) of fuel cell stack were carried out under various operating conditions. This fuel cell stack can be thawed from -20$^{\circ}$C within 25s and the voltage change was found to be comprised of 4 steps; the first step is the voltage decrease by overpotential, the second step is the voltage increase by the cell temperature increase, the third step is the voltage decrease by ice blocking, and the last step is the voltage increase by thawing. Bootstrap startup was failed after shutdown at temperature under 40$^{\circ}$C because of much condensed water in the fuel cell. Quantitative estimation of cold start capability have been demonstrated by ice blocking test(IBT). In the results, it was found that cold start capability was improved double every 10$^{\circ}$C from 30$^{\circ}$C to 65$^{\circ}$C and enhanced by 30% at the condition of SR 3/4 compared to SR 1.5/2.0 and enhanced by 20% with dry purge condition compared to with RH 50% purge condition.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.208-215
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• 2009

PEMFC stack power output is needed to be around 100 kW to meet the requirements of automotive application and scaling-up the active area of the stack cells will allow a higher power. In the case of scaling-up the active area of cells, it is difficult to obtain uniform in-plane internal conditions such as temperature, relative humidity and stoichiometry of the feed gas. These ununiformity with the location in the cell would affect both the performance and durability of the stack, so it is important to understand phenomena in the cell for improving them. In this study, the current density, electrochemical resistance and performance distribution measurement was performed to understand the ununiformity in a single cell using in-situ method; (1) Current Density Distribution (CDD) Device and (2) Segmented Cell Fixture. The influence of location of feed gas on the performance of a single cell was experimentally measured and discussed by using a segmented single cell which was composed of 8 compartments. The correlation between the location and performance in a single cell was discussed by these two tools and it was extended between the local characterization and the durability in a MEA by comparing the used cell with a fresh one. It was also studied in terms of electrochemistry by Electrochemical Impedance Spectroscopy.

• Korean Journal of Occupational Health Nursing
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• v.21 no.3
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• pp.192-200
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• 2012

Purpose: The purpose of this study aimed to investigate job stress levels of occupational health managers and whether job stress levels were affected by various factors such as size and types of company and work-related characteristics of occupational health managers. Methods: The study was conducted from May to September 2011 in the chemicals manufacturing factories in Korea and total subjects were 59 occupational health managers. We measured job stress levels of occupational health managers using Korean occupational stress scale (KOSS) questionnaires and the information of company characteristics was obtained using a self-reported questionnaire. Results: The characteristics of company such as type, size and industries and job characteristics of occupational health managers were significant factors in job stress. Job demand, job control, job insecurity, organizational system and occupational environment scores were significantly associated with type, size and industries of company. In multiple regression analyses, we found that job demand was significantly associated with occupational position and type of company, and job insecurity was significantly associated with working hour. Also, we found that lack of reward was significantly associated with education level, speciality, duration of work and hour and type of company. Conclusion: These results indicate that job stress of occupational health managers is significantly associated with work-related characteristics and company's characteristics.

• Safety and Health at Work
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• v.5 no.2
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• pp.60-65
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• 2014

Background: To elucidate the relationship between safety culture maturity and safety performance of a particular company. Methods: To identify the factors that contribute to a safety culture, a survey questionnaire was created based mainly on the studies of $Fern{\acute{a}}ndez-Mu{\tilde{n}}iz$ et al. The survey was randomly distributed to 1000 employees of two oil companies and realized a rate of valid answer of 51%. Minitab 16 software was used and diverse tests, including the descriptive statistical analysis, factor analysis, reliability analysis, mean analysis, and correlation, were used for the analysis of data. Ten factors were extracted using the analysis of factor to represent safety culture and safety performance. Results: The results of this study showed that the managers' commitment, training, incentives, communication, and employee involvement are the priority domains on which it is necessary to stress the effort of improvement, where they had all the descriptive average values lower than 3.0 at the level of Company B. Furthermore, the results also showed that the safety culture influences the safety performance of the company. Therefore, Company A with a good safety culture (the descriptive average values more than 4.0), is more successful than Company B in terms of accident rates. Conclusion: The comparison between the two petrochemical plants of the group Sonatrach confirms these results in which Company A, the managers of which are English and Norwegian, distinguishes itself by the maturity of their safety culture has significantly higher evaluations than the company B, who is constituted of Algerian staff, in terms of safety management practices and safety performance.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.161-161
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.162-162
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.585-586
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• 2005

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2019.05a
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• pp.185-186
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• 2019

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.43-44
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• 2006

Characteristics of hydrogen sensors for realization of transformer diagnosis system was studied, sensors used in this work are commercialized for detecting hydrocarbons or hydrogen gases. Based on the experimental results, the sensing characteristics of A company showed the high value even at the lower concentration of 20ppm, and it showed a saturation tendency with increasing it above 500ppm. In the case of B company, it showed the linear characteristics from 20ppm to 7000ppm. In addition, the output acquired from C company was amplified by external circuits due to its low output, and its adequate operation region was above 500ppm. Therefore, it is likely that these sensors are possible to apply for realization of transformer diagnosis system due to the different sensing characteristics of these sensors.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1511-1515
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• 2004

Machine vision system plays an important role in factory automation. Its many applications are found in automobile manufacturing industries, as an eye for robotic automation system. In this paper, an automobile position measuring vision system(APMVS) applicable to manufacturing line for under body painting of a car is introduced. The APMVS measures position and orientation of the car body to be sealed or painted by the robots. The configuration of the overall robotic sealing/painting system, design and application procedure, and application examples are described.