• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.73.2-73.2
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• 2019

The physical origin of low escape fractions of ionizing radiation derived from Lyman-break galaxies (LBGs) at z ~ 3 - 4 is a puzzle in the theory of reionization. We perform idealized disk galaxy simulations to investigate how galactic properties, such as metallicity and gas mass, affect the escape of Lyman continuum (LyC) photons using radiation-hydrodynamic code RAMSES-RT, with strong stellar feedback. We find that the luminosity-weighted escape fraction from a metal-poor (Z=0.002) galaxy embedded in a halo of mass M_h ~ 10¹¹ M_⊙ is 〈f^3D_esc〉 ~ 8%. However, when the gas metallicity is increased to Z=0.02, the escape fraction is significantly reduced to 〈f^3D_esc〉 ~ 1%, as young stars are enshrouded by their birth clouds for a longer period of time. On the other hand, increasing the gas mass by a factor of 5 leads to 〈f^3D_esc〉 ~ 4%, as LyC photons are only moderately absorbed by the thicker disk. Our experiments seem to suggest that high metallicity is primarily responsible for the low escape fractions observed from LBGs, supporting the scenario in which the escape fraction has a negative correlation with halo mass. Indeed, our simulated galaxy with the typical metallicity of LBGs (Z=0.006) shows the relative escape fraction of 8%, consistent with recent observations of galaxies with M₁₅₀₀ = -20.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.4
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• pp.63-71
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• 2012

Recently, because most of buildings in the city become bigger and higher, so various convenient facilities and high-tech management skills are required to prevent potential disasters. Especially, because fires in huge buildings can cause serious damage, technologies and methods that help people quickly and safely to escape from the building is very important to extinguish the fire in initial state and to minimize the damage. This paper suggests a context-aware service system that can provide optimal escape routes to tenants with their smart-phones. The proposed system collects contexts with real time through USN(Ubiquitous Sensor Network) and provides an optimum escape route based on the collected contexts through service users' smart phones. In addition, The system provides not only safe routes from the fire but also valuable information for rescue operations with real time.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.79-85
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• 2017

It is critical that passengers should be given timely and correct escape or evacuation guidance from captain and crews when there are hazardous situations in a ship. Otherwise the consequences could be disastrous as "SEWOL Ferry" the South Korean passenger ship which sank in southern coastal area on 16th April 2014. Due to the captain's delayed evacuation decision and lack of sufficient number of crews to guide passengers' evacuation, the accident recorded many casualties, most of whom were high school students (302 passengers sank down with the ship while 172 rescued). Building a passenger ship with well-designed physical escape routes is one thing and guiding passengers to those escape routes in real disaster situation is another. Passengers get panic and move to a wrong direction, bottleneck makes situation worse, and even crews get panic also - passive static escape route signage and small number of trained crews might not be enough to take care of them. SESS (Smart Escape Support System) is being developed sponsored by South Korea Ministry of Ocean and Fisheries starting from 2016 with 4 years of roadmap. SESS comprises multiple active dynamic signage devices which communicate with real-time escape routing server software via LoRa (Long Range) proprietary wireless network.

• The Journal of the Korea Contents Association
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• v.21 no.10
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• pp.217-226
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• 2021

Based on the theory of use and satisfaction, this study investigated the strength of TikTok usage motives (entertainment, information-seeking, interaction, self-expression, and escape) and the effect of each motive on users' adherence (frequency of use, time of use). investigated. After conducting a survey on TikTok Chinese users and removing insincere answers, 101 survey results were analyzed. The analysis results are as follows: First, the intensity of motivation for using TikTok was in the following order: entertainment-seeking, information-seeking, interaction, self-expression, and escape. Among them, the motives of pursuit of entertainment and escape were higher in females than in males. And the motives of pursuit of entertainment and escape were higher in the case of women than in the case of men. Second, as a result of analyzing the effect on user adhesion, the influence of the users' entertainment pursuit motive, interaction motive, and escape motive was significant for the frequency of use, and the influence of interaction was high. Third, the influence of entertainment-seeking motives and escape motives was found to be significant for use time. This means that users often use TikTok for entertainment, interaction, and escapism, and longer TikTok usage time for entertainment or escapism.

• Fire Science and Engineering
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• v.22 no.3
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• pp.287-292
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• 2008

In this study, the evacuation training were performed in a high school building in Cheong-Ju and compared with the simulation program (Simulex). Also numerical analysis of room fire in school building was conducted by fire model (FDS, CFAST) and evaluated the available safe egress time for the safety assessment. As a result, the 8% of total egress persons were failed to escape at evacuation training and 40% of total egress persons were failed to escape at Simutex simulation. Simutex program was not reflected the real escape conditions, such as evacuation route, refuge place, etc.

• Fire Science and Engineering
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• v.25 no.3
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• pp.28-41
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• 2011

Regulation of Escape and fire-prevention of Building of South Korea were enacted as a part of building codes in 1962. Since it was enacted, the law has gone through many changes. In this study, evaluated the fire safety of the law about the case of a hotel that the fire risk are expected to be higher whenever it was changed. As a result, the current law has gotten better in tire safety since it was enacted. However, especially it could be confirmed that the evacuation safety is insufficient in the lower level of hotel building. In the case of accommodation, because the occupants become aware of fire lately, they have not enough time to escape. Therefore, this study suggests that it is needed to come up with an effective counterplan about the interior finish materials, fire door and fire compartments that the smoke layer descending time is longer.

• Journal of the Chungcheong Mathematical Society
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• v.16 no.1
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• pp.7-14
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• 2003

Let $P_c(z)=z^n+c$ be a complex polynomial with an integer $n{\geq}2$. We derive a criterion that the critical orbit of $P_c$ escapes to infinity and investigate its applications to the degree-n bifurcation set. The intersection of the degree-n bifurcation set with the real line as well as with a typical symmetric axis is explicitly written as a function of n. A well-defined escape-time algorithm is also included for the improved construction of the degree-n bifurcation set.

• Fire Science and Engineering
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• v.25 no.1
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• pp.13-18
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• 2011

In the disaster prevention design, it is important point to secure escape way at event of fire which makes people away from the fire more quickly and safely. Development of construction techniques leads to build many skyscrapers, and skyscrapers contains various dangers and increase levels of disaster. At basic design stage for skyscrapers, evacuation scenario is considered that occupants are escape using escape stairs and emergency elevators simultaneously at fire, but there is no evacuation program to simulate using escape stairs and emergency elevators at the same time. In this study, evacuation simulation is performed using method of VR which is based on Virtools of 3DVIA Co., and Simulex of IES Co. for safety and effectiveness where occupants are escape using escape stairs and emergency elevators simultaneously at the fire.

• The Korean Journal of Physiology
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• v.29 no.2
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• pp.291-299
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• 1995

Lateral giant (LG)-mediated escape response of crayfish is sensitized by natural traumatic events. Such sensitization has previously been shown to be associated with increased transmission between primary afferents and sensory interneurons at the cholinergic synapse of LG escape reflex circuit. In the present study, it was firstly investigated as to whether transmission is also altered at other synapses of the LG-escape reflex circuit by traumatic shock-induced sensitization. Evidence that traumatic shock also directly affects the excitability of lateral giants is now provided by the finding that traumatic shock produces a significant reduction of the time needed for LG to recruit its contralateral homologue, which is defined as commissural delay. Octopamine, a naturally occurring neuromodulator in the crayfish nerve cord, has also been shown to enhance transmission at the cholinergic synapse between primary afferents and sensory interneurons, and has been conjectured to mediate sensitization. Like traumatic shock, $octopamine\;(10^{-5}-5{\times}10^{-4}\;M)$ also enhanced the efficacy of commissural transmission between lateral giants, as indicated by a significant reduction of commissural delay. This effect was blocked by an octopamine antagonist phentolamine, suggesting a specific action of octopamine on the octopamine receptor present on LGs. These observations suggest that both traumatic shocks and octopamine may cause a rather broad alteration in the excitability of the crayfish nervous system that contributes to the sensitization of the LG escape response.

• Journal of the Korean housing association
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• v.19 no.5
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• pp.103-110
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• 2008

The purpose of this study is to know how visual-field obstruction from fire smoke influences a resident's necessary time to reach fire escape and evacuation movement in a high-rise apartment housing. Generally, fire smoke not only gives visual-field obstruction and breath troubles to residents but interrupts their evacuation behavior. If a fire smoke layer is formed in the core department when evacuee enters at the evacuation staircase until, residents will be made to undergo a range of vision obstacle. In order to set a situation like that, participants wore eye bandage which had been made especially before the experiment. Also as a comparative standard, through no.1442 Japanese construction ministry notices about the building evacuation safety verification method, this study calculated smoke layer's dissent time and evacuation time. Then to compare with the former, the participants without an eye bandage joined a experiment once again. This study has understood how fire smoke effects on one's evacuation delay by analyzing residents' evacuation time to reach the staircase and movement route, however, in this study a toxic gas is not considered because it might threaten participants not to breathe.