• Geomechanics and Engineering
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• v.30 no.6
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• pp.539-549
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• 2022

Accidental anchor drop can cause disturbances to seabed materials and pose significant threats to the safety and serviceability of submarine structures such as pipelines. In this study, a series of anchor drop tests was carried out to investigate the penetration mechanism of a Hall anchor in sand and clay. A special anchor drop apparatus was designed to model the inflight drop of a Hall anchor. Results indicate that Coriolis acceleration was the primary cause of large horizontal offsets in sand, and earth gravity had negligible impact on the lateral movement of dropped anchors. The indued final horizontal offset was shown to increase with the elevated drop height of an anchor, and the existence of water can slow down the landing velocity of an anchor. It is also observed that water conditions had a significant effect on the influence zone caused by anchors. The vertical influence depth was over 5 m, and the influence radius was more than 3 m if the anchor had a drop height of 25 m in dry sand. In comparison, the vertical influence depth and radius reduced to less than 3 m and 2 m, respectively, when the anchor was released from 10 m height and fell into the seabed with a water depth of 15 m. It is also found that the dynamically penetrating anchors could significantly influence the earth pressure in clay. There is a non-linear increase in the measured penetration depth with kinematic energy, and the resulted maximum earth pressure increased dramatically with an increase in kinematic energy. Results from centrifuge model tests in this study provide useful insights into the penetration mechanism of a dropped anchor, which provides valuable data for design and planning of future submarine structures.

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.485-492
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• 2021

Vision-based autonomous precision landing technology for UAVs requires precise position estimation and landing guidance technology. Also, for safe landing, it must be designed to determine the safety of the landing point against ground obstacles and to guide the landing only when the safety is ensured. In this paper, we proposes vision-based navigation, and algorithms for determining the safety of landing point to perform autonomous precision landings. To perform vision-based navigation, CNN technology is used to detect landing pad and the detection information is used to derive an integrated navigation solution. In addition, design and apply Kalman filters to improve position estimation performance. In order to determine the safety of the landing point, we perform the obstacle detection and position estimation in the same manner, and estimate the speed of the obstacle using LSM. The collision or not with the obstacle is determined based on the CPA calculated by using the estimated state of the obstacle. Finally, we perform flight test to verify the proposed algorithm.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.29-33
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• 2012

This paper is an attempt to give a concise overview of the state-of-the-art in the recent liquid hydrogen safety researches with unwanted event progress. The vessel of liquified hydrogen may fail and liquid hydrogen spilled. The hydrogen will immediately start to evaporate above a pool and make a hydrogen cloud. The cloud will disperse and can produce a vapor cloud explosion. The vessel containing the liquid hydrogen may not be able to cope with the boil-off due to heat influx, especially in case of a fire, and a BLEVE may occur. In equipment where it exists as compressed gas, a leak generates a jet of gas that can self-ignite immediately or after a short delay and produce a jet flame, or in case it ignites at a source a certain distance from the leak (delayed ignition), a flash fire occurs in the open and with confinement a deflagration or even detonation may develop. The up-to-date knowledge in these events, recent progress and future research are discussed in brief.

• Fire Science and Engineering
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• v.23 no.2
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• pp.67-77
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• 2009

The purpose of this study is to deal with fire fighting safety education primarily among the fields of child safety education. So, first of all, this study considered the theoretical background of fire fighting safety education. And this study analyzed the present state and cases of safety accidents in elementary schools. And by focusing on the fire fighting science class for elementary schools which Gyeonggi-do Goyang fire station is executing now, this study analyzed the educational outline, present state, educational goal, and content of fire fighting science class, and conducted the satisfaction survey through questionnaire over the elementary school students participating in fire fighting science class and the fire fighting officers in charge of fire fighting science class. On basis of this research, by developing the new field of fire fighting education and publicity into the program which can diffuse the fire fighting-related chemical experiment based on the science of chemistry and physics in the future and so provide the pleasure and surprise of experiencing directly not only natural fire fighting education and publicity but also learning and the common sense of fire fighting, this study tried to present the alternatives about the measures for activating the fire fighting safety education in elementary schools.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.2
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• pp.43-49
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• 2012

Purpose : This study is to supply basal data need to development of First-Aid education program for female college students of non-health department that we surveyed safety awareness practice, First-Aid knowledge, educational requirement and necessity of the female college students of health and non-health department. Methods : This date was collected from September 1th in 2012 until October 5th by 5 person selected of which explain to purpose and method of the writing. We distributed the subject questionnaire of total 410 and analyzed questionnaire 385 only. Results : The results of this study are follows. First, the health group was higher than non-health group in conductive score of safety awareness and score of First-Aid knowledge in female students and there was statistically significant difference. Second, There was significant difference in Economical state, Educational state of the Safety awareness Practice score and First-Aid knowledge score about the general characteristic of the female college students of health department. Third, there wasn't significant difference in most of all item of the Safety awareness Practice score and First-Aid knowledge score about the general characteristic of the female college students of non-health department. Conclusion : Finally, We found that the female college students of health department lower than the female college students of non-health department in First-Aid knowledge level and surveyed that they felt the needs of First-Aid education. Therefore, there are able to need the opening of a course in order to raise the quality of safety awareness and First-Aid knowledge or to needs construction of educational system in continuously.

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1321-1329
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• 2016

To get an insight into the operating characteristics of the passive residual heat removal system of molten salt reactors, a two-phase natural circulation test facility was constructed. The system consists of a boiling loop absorbing the heat from the drain tank, a condensing loop consuming the heat, and a steam drum. A steady-state experiment was carried out, in which the thimble temperature ranged from $450^{\circ}C$ to $700^{\circ}C$ and the system pressure was controlled at levels below 150 kPa. When reaching a steady state, the system was operated under saturated conditions. Some important parameters, including heat power, system resistance, and water level in the steam drum and water tank were investigated. The experimental results showed that the natural circulation system is feasible in removing the decay heat, even though some fluctuations may occur in the operation. The uneven temperature distribution in the water tank may be inevitable because convection occurs on the outside of the condensing tube besides boiling with decreasing the decay power. The instabilities in the natural circulation loop are sensitive to heat flux and system resistance rather than the water level in the steam drum and water tank. RELAP5 code shows reasonable results compared with experimental data.

• Wind and Structures
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• v.29 no.4
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• pp.279-297
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• 2019

Strong winds threaten the safety of vehicles on long-span bridges considerably, which could force traffic authorities to reduce speed limits or even close these bridges to traffic. In order to maintain the safe and economic operation of a bridge, a reasonable evaluation of the driving safety on that bridge is needed. This paper aims at carrying outdriving safety analyses for three types of vehicles on a long-span bridge in crosswinds by considering the aerodynamic interference between the bridge and the vehicles based on the wind-vehicle-bridge coupling vibration analysis. Firstly, CFD numerical simulations along with previously obtained wind tunnel testing results were used to determine the aerodynamic force coefficients of the three types of vehicles on the bridge. Secondly, the dynamic responses of the bridge and the vehicles under crosswinds were simulated, and based on those, the driving safety analyses for the three types of vehicles on the bridge were carried out for both cases considering and not considering the aerodynamic interference between the vehicles and the bridge. Finally, the effect of the aerodynamic interference on the safety of the vehicles was investigated. The results show that the aerodynamic interference between the bridge and the vehicles not only affectsthe accident critical wind speed but also the accident type for all three types of vehicles. Such effects are also different for each of the three types of vehicles being studied.

• Proceedings of the Safety Management and Science Conference
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• 2006.04a
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• pp.421-428
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• 2006

It is an hot issue to reduce vibration for improving quality, reliability and safety in railway vehicles including magnetic levitation, monorail way, surface car etc. This paper aims at literature survey in rolling stocks vibration standards. Firstly, we investigate literature concerned vibration test standards and compare these standards. Secondly, we give some suggestions for future study and developing new test standards.

• Journal of Multimedia Information System
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• v.2 no.3
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• pp.281-286
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• 2015

This article considers Honeywell solutions in the branch of integration of subsystems of industrial safety and security for industrial enterprises with the creation of a unified Human-machine interface for centralized management and control of safety at the plant.

• Journal of the Korea Safety Management & Science
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• v.1 no.1
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• pp.29-39
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• 1999

Human sensibility ergonomics is the technique that qualities man's sensibility, measures and evaluates it Quantitatively and makes man's life comfortable, safe and delightful by applying it to products or environmental projects. This study consider the sensibility factor of Sasang constitutional medicine, five elemental properties, and Biorhythm in terms of human sensibility ergonomics. And this study measure reaction-time dependent on a temperament or a state and evaluate the differences of reaction-times objectively with the comparison and analysis using the ANOVA. We can harness it for job design.