• Journal of the Korean Society of Safety
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• v.39 no.2
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• pp.38-43
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• 2024

Recently, with the expanding market for electronic devices and electric vehicles, secondary battery usage has been on the rise. Lithium-ion batteries are particularly popular due to their fast charging times and lightweight nature compared to other types of batteries. A secondary battery consists of four components: anode, cathode, electrolyte, and separator. Generally, the positive and negative electrode materials of secondary batteries are composed of an active material, a binder, and a conductive material. Acetylene Black (AB) is utilized to enhance conductivity between active material particles or metal dust collectors, preventing the binder from acting as an insulator. However, when recycling waste batteries that have been subject to high usage, there is a risk of fire and explosion accidents, as accurately identifying the characteristics of Acetylene Black dust proves to be challenging. In this study, the lower explosion limit for Acetylene Black dust with an average particle size of 0.042 ㎛ was determined to be 153.64 mg/L using a Hartmann-type dust explosion device. Notably, the dust did not explode at values below 168 mg, rendering the lower explosion limit calculation unfeasible. Analysis of explosion delay times with varying electrode gaps revealed the shortest delay time at 3 mm, with a noticeable increase in delay times for gaps of 4 mm or greater. The findings offer fundamental data for fire and explosion prevention measures in Acetylene Black waste recycling processes via a predictive model for lower explosion limits and ignition delay time.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.11a
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• pp.378-381
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• 2007

지상의 침수와 지하공간의 침수는 많은 부분에서 발생 및 진행 메커니즘이 다르므로, 침수시 요구되는 대응방안 또한 많은 차이를 나타내고 있다. 일반적으로 지하구내의 침수 피해는 지상에 비해 피해 규모가 막대할 뿐만 아니라 복구에도 많은 어려움이 있다. 생명과 재산의 피해를 최소화할 수 있는 적절한 대책이 필요하다. 본 논문에서는 영상처리와 퍼지 제어를 적용해서 지하구내 침수 상황을 감시 ${\cdot}$ 통제하고 안전성을 평가하는 알고리즘과 시스템을 제안한다.

• Journal of the Korean earth science society
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• v.41 no.4
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• pp.391-404
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• 2020

This study identified and examined earth science education department programs in Korea. Major courses provided by 11 universities and their course requirements were analyzed, and the main research results are as follows. First, many basic courses, other major requisite, and elective courses are provided in geology, astronomy, and atmospheric science. oceanography, geophysics, earth environmental science, and natural disaster and energy resources had fewer major requisite courses provided in addition to basic courses, and few elective courses were offered. Second, many courses in science education focused on earth science, while others focused on general science and there were few courses that covered education theory regarding the specific subject. Third, science course application requirements emphasized the understanding of science in general or of earth science specifically. From the above results, additional studies are proposed to reflect on the current state and supplement these programs.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.366-373
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• 2006

In order to reduce the secondary earthquake disaster resulting from the damage of gas facilities it is indispensable to establish an early response system on the basis of damage prediction. In this study the procedure of damage prediction for gas facilities is proposed and applied to the gas supply model area. Model area is divided into several little blocks. The soil condition and the characteristics of facilities were investigated at each block. Using fragility curves of facilities the damage level was analyzed under various seismicities. It is confirmed that the exposure gas pipe line in several blocks is damaged seriously by the collapse of building structures.

• Journal of Radiation Protection and Research
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• v.49 no.2
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• pp.65-67
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• 2024

This review is based on articles published in Japanese Journal of Health Physics on "Radiation-exposed medical care and waste" related to Tokyo Electric Power Company Incorporated (TEPCO)'s Fukushima Daiichi Nuclear Power Station accident. Here, we have considered three original articles; one technical data, one special article, one 50^th anniversary article, one preface, three topics, and two cases of From Japan to the World (J to W). These articles have reported the system and standards that were established after the accident. Moreover, they have summarized rare experiences such as the fumbling response at the time and the evaluation of samples in that disaster. These articles constitute valuable records of the situation.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.27 no.3
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• pp.164-172
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• 2016

Objectives: This study attempted to evaluate the usefulness and direction of development of post-traumatic assessment and interventions based on the opinions of psychiatrics and disaster and trauma-related experts using the Delphi survey technique. Methods: In-depth individual interviews served as the pre-survey and were followed by Delphi primary and secondary surveys. Specialists in child and adolescent mental health, psychological support professionals specialized in disasters and related practitioners with experience of disasters in Korea completed a set of questionnaires and participated in focus group interviews and in-depth individual interviews on post-traumatic assessment and intervention. Results: We found that the following issues have a significant impact on the interventions after disasters: the proper time of the initial interview in the event of a disaster, assessment notices, aged assessment services, mandatory enforcement measures, scale screening and treatment intervention elements, symptoms degree classification, intervention standardization, the use of a levelled program, care unit environment, and operation plan. Conclusion: This study proposed effective mental health intervention measures and has implications for the development of evaluation treatment protocols after disasters.

• Fire Science and Engineering
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• v.34 no.1
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• pp.135-141
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• 2020

The first case of Middle East Respiratory Syndrome (MERS) was reported in Korea in 2015, after a Korean man from Bahrain tested positive for the infection. After first eruption, there were numbers of secondary infectees and whole country were frightened. At the time, isolated ambulances were available but few, and there was no specific way to prevent contamination during transfer. Therefore, Seoul National University Hospital and the University of Seoul developed isolation units and air filters. Four years after the MERS outbreak, this study measured the differential pressure inside and outside the small isolation units based on the differential pressure and air flow derived from simulation and testing, and proposed minimum values for virus leakage and internal sealing. A performance evaluation and testing method for the transfer equipment is proposed. The critical function of the small isolated transport equipment was defined and selected as an evaluation item; performance evaluation was carried out by simulating a real-world case. The results provide the proper pressure configuration of positive and negative pressure inside the segregation feeder; the clear criteria for the HEPA filter; and the performance criteria for the segregation feeder and air purifier.

• Journal of the Korea Convergence Society
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• v.12 no.3
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• pp.77-83
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• 2021

The purpose of the study is to evaluate the effect on medical application and convergence for the efficient disaster responses in the massive radiological events by comparison of two types of survey-meters(hand held survey-meter and transportable portal monitor). In the simulated radiation disaster drill, twelve participants randomly wore a personal protective equipments (PPE) with twelve check source. We measured participants to detect five real radioactive sources of the twelve check sources, using two types of survey meters. The primary outcome was the measuring time. The secondary outcome was the sensitivity and specificity of the detection of the real radioactive source. The average time by the hand held survey meter was 231.9 ± 116.6 seconds, and the time by transportable portal monitor was statistically shorter 8.690 ± 1.667 seconds. There was no difference in the sensitivity and specificity between two survey meters. The transportable portal monitor survey meter was considered to have medical application and play an important role in radiological disasters.

• The Journal of the Korea Contents Association
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• v.22 no.8
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• pp.527-541
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• 2022

The purpose of this study is to explore the economic hardship experiences of low-income single-parent families by COVID-19 to find ways to improve after COVID-19. To this end, 10 single parents with children under the secondary school age were recruited through snowball sampling method and in-depth interviews with economic activities, income, expenditure, and economic life. As a result of the study, participants suffered from unemployment and the disappearance of extra income activities in the early stages of COVID-19, additional expenses incurred by children's food and increased utility bills. In addition, it was recognized that COVID-19 has come to be more difficult and unequal to single-parent families of low-income women. It was found that the temporary living difficulties were resolved with disaster support funds, and it was helpful in the short term by spending according to priorities such as overdue monthly rent, food expenses, children's academy expenses, and purchasing home appliances. However, it was recognized that disaster support funds were inappropriate for customized disaster support and long-term and selective support was necessary. In the conclusion, to improve economic problems after COVID-19, it proposed measures to improve social welfare policies and practices

• Journal of the Korean Society of Safety
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• v.38 no.5
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• pp.8-14
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• 2023

Lithium ions can induce the thermal runaway phenomenon and lead to reignition due to electrical, mechanical, and environmental factors such as high temperature, smoke generation, explosions, or flames, which is extremely likely to create safety concerns. Therefore, one of the ways to improve the flame retardancy of the electrolyte is to use a flame-retardant additive. Comparing the associated characteristic value of existing substances with the required experimental value, it was found that these values were either considerably different or were not documented. It is vital to know a substance's combustion characteristic values, flash point, explosion limit, and autoignition temperature (AIT) as well as its combustion characteristics before using it. In this research, the flash point and AIT of materials were measured by mixing a highly volatile and flammable substance, diethyl carbonate (DEC), with flame-retardant dimethyl methylphosphonate (DMMP). The flash point of DEC, which is a pure substance, was 29℃, and that for DMMP was 65℃. Further, the lower explosion limit calculated using the measured flash point of DEC was 1.79 Vol.%, while that for DMMP was 0.79 Vol.%. The AIT was 410℃ and 390℃ for DEC and DMMP, respectively. In particular, since the AIT of DMMP has not been discussed in any previous study, it is necessary to ensure safety through experimental values. In this study, the experimental and regression analysis revealed that the average absolute deviation (ADD) for the flash point of the DEC+DMMP DEC+DMMP system is 0.58 sec and that the flash point tends to increase according to changes in the composition employed. It also revealed that the AAD for the AIT of the mixture was 3.17 sec and that the AIT tended to decrease and then increase based on changes in the composition.