• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.218-224
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• 2014

Biodegradable conductive composite films of polylactic acid(PLA) were prepared with various amounts of polyaniline(PAni) doped with dodecylbenzenesulphonic acid (DBSA) by solution blending technique to identify their mechanical and electric properties. 15 mol% of DBSA doped PAni was easily obtained by polymerizing of aniline in the presence of APS and DBSA in THF at $0^{\circ}C$. FE SEM characterization showed that PAni were well spread on the PLA domains. The tensile strength of composite film with 15 wt% of PAni was significantly decreased from $565.3kg_f/cm^2$ for PLA film itself to $309.7kg_f/cm^2$. Elongations of all PAni/PLA composite films were also decreased up to 3-6%. Electrical conductivity of $2.9{\times}10^{-3}$ S/cm could be achieved for the composite film containing 15 wt% of PAni-DBSA. Thermal stability of these composite films measured by thermogravimetric analysis(TGA) showed a slight decrease with the amount of PAni in PAni/PLA composite films at temperature lower than $300^{\circ}C$. However, the final weight of char was strongly depended with the amount of PAni in original composite films. Conclusively, PAni/PLA composite films containing more than a 15 wt% of PAni could be used for intercepting electromagnetic and preventing electrostatic applications.

• Journal of the Korean Society of Safety
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• v.31 no.3
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• pp.42-46
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• 2016

In LCD Display or semiconductor manufacturing processes, the anti-static technology of glass substrates and wafers becomes one of the most difficult issues which influence the yield of the semiconductor manufacturing. In order to overcome the problems of wafer surface contamination various issues such as ionization in decompressed vacuum and inactive gas(i.e. $N_2$ gas, Ar gas, etc.) environment should be considered. Soft X ray radiation is adequate in air and $O_2$ gas at atmospheric pressure while UV radiation is effective in $N_2$ gas Ar gas and at reduced pressure. At this point of view, the "vacuum ultraviolet ray ionization" is one of the most suitable methods for static elimination. The vacuum ultraviolet can be categorized according to a short wavelength whose value is from 100nm to 200nm. this is also called as an Extreme Ultraviolet. Most of these vacuum ultraviolet is absorbed in various substances including the air in the atmosphere. It is absorbed substances become to transit or expose the electrons, then the ionization is initially activated. In this study, static eliminator based on the vacuum ultraviolet ray under the above mentioned environment was tested and the results show how the ionization performance based on vacuum ultraviolet ray can be optimized. These vacuum ultraviolet ray performs better in extreme atmosphere than an ordinary atmospheric environment. Neutralization capability, therefore, shows its maximum value at $10^{-1}{\sim}10^{-3}$ Torr pressure level, and than starts degrading as pressure is gradually reduced. Neutralization capability at this peak point is higher than that at reduced pressure about $10^4$ times on the atmospheric pressure and by about $10^3$ times on the inactive gas. The introductions of these technology make it possible to perfectly overcome problems caused by static electricity and to manufacture ULSI devices and LCD with high reliability.

• Journal of the Korean Society of Safety
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• v.34 no.5
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• pp.37-45
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• 2019

The characteristic of fire and explosion related to electrostatic discharge is that it is difficult to reproduce the electrostatic charge and discharge phenomenon in addition to the large human and material damage. Therefore, in order to prevent accidents and disasters related to electrostatic in fire and explosion hazard areas, it is important to manage the level of electrostatic in a safe manner from the perspective of system between industrial facilities and human bodies. Rule 325 of the Occupational Safety and Health Regulations, "Prevention of Fire / Explosion due to Electrostatic", requires the use of grounding, conductive materials, humidification and electrification in order to prevent the risk of disaster caused by static explosion and electrostatic in the production process. In order to comply with these measures, related technologies, standards and systems are needed from the viewpoint of preventive measures related to electrostatic in fire and explosion hazard areas, but in Korea, it is still insufficient. Therefore, technical, institutional and managerial measures are needed as a precautionary measure to improve the level of ESD safety in fire and explosion hazard areas and prevent electrostatic related injury. In Korea, we analyzed the current status and characteristics of electrostatic related disaster by using the statistics of industrial accident and fire statistics of the Ministry of Employment and Labor. We also analyzed the current status and characteristics of electrostatic related disasters in Japan using JNIOSH accidents and disasters investigation cases and JNIOSH fire accident data of Japan Fire Bureau. The purpose of this study is to compare and analyze the current status of electrostatic related accidents and disasters in Korea and Japan in order to improve the safety management of electrostatic in fire and explosion hazard areas. In order to prevent accidents and disasters in the industrial field, The technical, institutional, and managerial measures to manage the level of electrostatic in a safe state were derived from the system point of view.

• Journal of The Korean Association For Science Education
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• v.44 no.1
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• pp.77-86
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• 2024

This study analyzed students' discourse and learning to investigate the impact of using Google Docs in science classes. The researcher, who is also a science teacher, conducted classes for 49 second-year middle school students. The classes included one using Google Docs and another using traditional paper worksheets covering identical content. Students' discourse collected from each class was compared and analyzed using Epistemic Network Analysis (ENA). The findings indicated that in the class using Google Docs, the proportion of discourse related to task was higher compared to the traditional class. More specifically, discourse regarding taking and uploading photos was prominent. However, such discourse did not lead to peer learning as intended by the teacher. An analysis based on achievement levels revealed that the class utilizing Google Docs had a relatively higher proportion of discourse from lower-achieving students. Additionally, differences were observed in the types of utterances and connection structures between the higher and lower-achieving students. The higher-achieving students took a leading role in providing suggestions and explanations, while the lower-achieving students played a role in transcribing them, with this tendency being more pronounced in the class using Google Docs. Lastly, students' changes in perception regarding the cause of static electricity were visualized using ENA. Based on the research findings, this study proposes strategies to enhance collaborative learning using Google Docs, including the use of open-ended problems to allow diverse opinions and outputs, and exploring the potential use of ENA to assess the learning effects of conceptual learning.