• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.981-988
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• 2023

A seismic event caused an accident at the Fukushima Nuclear Power Plant, which further resulted in simultaneous accidents at several units. Consequently, this incident has aroused great interest in the safety of nuclear power plants worldwide. A reasonable safety evaluation of such an external event should appropriately consider the correlation between SSCs (structures, systems, and components) and the probability of failure. However, a probabilistic safety assessment in current nuclear industries is performed conservatively, assuming that the failure correlation between SSCs is independent or completely dependent. This is an extreme assumption; a reasonable risk can be calculated, or risk-based decision-making can be conducted only when the appropriate failure correlation between SSCs is considered. Thus, this study analyzed the effect of the failure correlation of SSCs on the safety of the system to realize rational safety assessment and decision-making. Consequently, the impact on the system differs according to the size of the failure probability of the SSCs and the AND and OR conditions.

• Investigative Magnetic Resonance Imaging
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• v.22 no.4
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• pp.218-228
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• 2018

Purpose: The objective of this study is to determine the effect of physical changes on MR temperature imaging at 7.0T and to examine proton-resonance-frequency related changes of MR phase images and T1 related changes of MR magnitude images, which are obtained for MR thermometry at various magnetic field strengths. Materials and Methods: An MR-compatible capacitive-coupled radio-frequency hyperthermia system was implemented for heating a phantom and swine muscle tissue, which can be used for both 7.0T and 3.0T MRI. To determine the effect of flip angle correction on T1-based MR thermometry, proton resonance frequency, apparent T1, actual flip angle, and T1 images were obtained. For this purpose, three types of imaging sequences are used, namely, T1-weighted fast field echo with variable flip angle method, dual repetition time method, and variable flip angle method with radio-frequency field nonuniformity correction. Results: Signal-to-noise ratio of the proton resonance frequency shift-based temperature images obtained at 7.0T was five-fold higher than that at 3.0T. The T1 value increases with increasing temperature at both 3.0T and 7.0T. However, temperature measurement using apparent T1-based MR thermometry results in bias and error because B1 varies with temperature. After correcting for the effect of B1 changes, our experimental results confirmed that the calculated T1 increases with increasing temperature both at 3.0T and 7.0T. Conclusion: This study suggests that the temperature-induced flip angle variations need to be considered for accurate temperature measurements in T1-based MR thermometry.

• Journal of the Society of Disaster Information
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• v.17 no.2
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• pp.341-350
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• 2021

Purpose: The purpose of this study is to present an analysis method to select priorities for areas where the traffic safety system is applied to reduce pedestrian accidents. Method: Using Kernel density analysis using the coordinate information of the accident point, we performed density analysis of elderly walking accidents and elderly jaywalking accidents, and analysis of the weight of two types of walking accidents. Result: As a result of density analysis of the weight considering elderly jaywalking accidents, it was analyzed that the density of pedestrian traffic accidents for th elderly was higher in Gunsan-si, Jeongeup-si, and Gimje -si compared to Jeonju-si, where the number of elderly pedestrian accidents were high. Conclusion: The analysis results of this study are judged to be possible to use objective indicators for the selection of target sites for the introduction of the traffic safety system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.4
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• pp.251-257
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• 2023

This study entailed an investigation of a tensile stress measurement method for prestressed concrete (PSC) tendons by utilizing external magnetization. The target of this study are PS structures that have been constructed and in use. An optimal external magnetization based elasto-magnetic (EM) sensor was designed using finite element analysis considering various factors, such as coil arrangement and size, that could influence the PS tendons inside the PSC girder. The residual tensile stress resulting from the external magnetization of the girder was then determined. Further, theoretical verification was performed using the numerical and material data used in the finite element analysis for sensor design. The calculated values of strength of magnetization at the target location were matched with the finite element analysis results. Thus, the designed sensor and the feasibility of magnetizing the tendons inside the PSC I-girder using an EM sensor were validated.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_2
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• pp.257-262
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• 2022

With the shortage of labor force in small and medium-size industries, the Korean Employment Permit System (EPS) continues to bring migrant workers. However, the question remains of the health and safety management of their migrant workers. Considering that a significant part of safety and health problems are caused by migrant workers due to a lack of information on identifying risk and inexperience in the field. Telephone interviews were conducted to investigate the migrant workers' perspectives on workplace safety practices. The survey focused on workers' accident histories, understanding of safety practices, and responding to industrial accidents. A total of 66 accidents occurred among 30 participants. 10 accidents were not reported to the employer (company), which the foreign workers judged to be minor injuries that should not be reported as accidents. 80.0% of the participants expressed dissatisfaction with the PPE they were using. Among various reasons lack of understanding due to language barriers, lack of awareness of the importance of safety, communication difficulties were major reasons for the caused accidents and potential health issues. It is necessary to improve the safety and health support system by providing practical support through specialized educational institutes with experts in the field. A legal framework and a proper safety management system need to be maintained. This study suggests changing the current policy to improve the health and safety of migrant workers by, establishing specialized educational institutes with locally grown foreign experts in the field.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.213-216
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• 2022

There has been an increase in video surveillance for public safety and security, which increases the video data, leading to analysis, and storage issues. Furthermore, most surveillance videos contain an empty frame of hours of video footage; thus, extracting useful information is crucial. The prominent framework used in surveillance for efficient storage and analysis is video synopsis. However, the existing video synopsis procedure is not applicable for creating an abnormal object-based synopsis. Therefore, we proposed a lightweight synopsis methodology that initially detects and extracts abnormal foreground objects and their respective backgrounds, which is stitched to construct a synopsis.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.73-74
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• 2023

본 논문은 교량 안전에 관련하여 CNN과 LSTM을 결합한 모델을 사용해 콘크리트 균열을 미리 에측한다. 이미지 데이터는 CNN을 통해 처리되고, 시계열 데이러는 LSTM을 통해 처리가 된다. 훈련된 모델을 사용해 새로운 이미지와 시계열 데이터에 대한 균열 예측을 수행한다.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.6
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• pp.569-576
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• 2021

Radar is a ground defense system that detects enemy aircraft and receives power from a mobile power supply in an emergency. Serious problems may occur if the equipment is damaged by impact during transportation for use. The US military standard MIL-STD-810H contains information on environmental tests such as shock and vibration applied to munitions. Therefore, in this study, the transient analysis of ANSYS 19.2 was performed using the impact data specified in MIL-STD-810H as an input value. Through this, the maximum stress generated in the impact environment of the mobile power supply container was derived, and the safety margin was calculated to confirm the reliability of the container.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.2
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• pp.61-74
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• 2021

Agriculture is most closely related to weather, and the government pursues stable food production by weather research. However, abnormal weather conditions have occurred frequently around the world in recent years, and stable food production has been threatened. Among them, heavy snow in winter tends to increase in frequency and size, which causes serious damage to greenhouses. Therefore, it is imperative to build a system reflecting various demands to reduce the damage to agricultural facilities caused by heavy snow. A business model can realize this as a way of commercialization, however, no suitable model has been presented to date. Therefore, this study aims to design a representative business model that can establish a safety system by distributing a greenhouse disaster prevention warning system for heavy snow to farms.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.47-53
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• 2019

Safety accidents at industrial sites can occur anytime, anywhere. Recently, research on the industrial safety management system based on the IoT has been actively conducted. However, most of the studies are studies of actions after safety accidents or simply monitoring. In this paper, the safety equipment was introduced before safety accidents occurred, and the subjects could be managed not only by workers but also by visitors. Also, it implements a system to prevent the accident by detecting the user's motion and situation periodically before a safety accident occurs. The implemented system is a system that attaches the device for safety management to the hard hat and can identify the safety situation by using the Bluetooth beacon device attached to the user's smartphone and the industrial site.