• Title, Summary, Keyword: safety distance

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Effect of one way reinforced concrete slab characteristics on structural response under blast loading

  • Kee, Jung Hun;Park, Jong Yil;Seong, Joo Hyun
    • Advances in concrete construction
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    • v.8 no.4
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    • pp.277-283
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    • 2019
  • In evaluating explosion-protection capacity, safety distance is broadly accepted as the distance at which detonation of a given explosive causes acceptable structural damage. Safety distance can be calculated based on structural response under blast loading and damage criteria. For the applicability of the safety distance, the minimum required stand-off distance should be given when the explosive size is assumed. However, because of the nature of structures, structural details and material characteristics differ, which requires sensitivity analysis of the safety distance. This study examines the safety-distance sensitivity from structural and material property variations. For the safety-distance calculation, a blast analysis module based on the Kingery and Bulmash formula, a structural response module based on a Single Degree of Freedom model, and damage criteria based on a support rotation angle were prepared. Sensitivity analysis was conducted for the Reinforced Concrete one-way slab with different thicknesses, reinforcement ratios, reinforcement yield strengths, and concrete compressive strengths. It was shown that slab thickness has the most significant influence on both inertial force and flexure resistance, but the compressive strength of the concrete is not relevant.

Establishment of Guardrail Distance for Safety of Reinforced Earth Retaining Wall by Vehide Collision (차량충돌에 대한 보강토 옹벽 안전성 확보를 위한 가드레일 설치거리)

  • Park, Kwon;Hong, Ki-Nam;Ahn, Kwang-Kuk
    • Journal of the Korean Society of Safety
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    • v.24 no.5
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    • pp.57-62
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    • 2009
  • In this study, the numerical analyses regarding the distance between the guardrail and the reinforced earth wall as parameter were performed to determine the safe distance of guardrail installed on reinforced earth wall from the reinforced earth wall. The analyses were fulfilled by increasing the distance between the guardrail and reinforced earth wall from 150mm to 750mm. The computer program used in this research is LS-DYNA, which is very' popular in analysis of vehicle collision. Ford single unit truck in NCAC was employed as the model of vehicle and the velocity of vehicle collision was 80km/hr. As a results of analyses, the safety of guardrail was secured regardless of the distance between the guardrail and block of reinforced earth wall. However, to secure the safety of block of reinforced earth wall the distance between the guardrail and block of reinforced earth wall should be over 600mm.

An Investigation on Actual Condition and the Influence of Safety on Elementary School Road by Types of Urban Spatial Structure (도시공간구조 유형별 초등학교 통학로 실태 및 안전도 영향규명 연구)

  • Kim, Tae-Ho;Kim, Seung-Hyun;Lee, Soo-Il
    • Journal of the Korean Society of Safety
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    • v.28 no.5
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    • pp.71-77
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    • 2013
  • This Study aims at investigating actual condition on attending school road of children and analyzing empirically the characteristics of cognition and the influence of safety on school road. This study findings are as follows : 1) Walking alone to go to school is the highest rates among Commuting Mode, and Commuting distance to school is nearly doubles than range of school zone(300 m). 2) Among characteristics of urban spatial structure affecting on influence classify safety of school road, 'Commuting Distance' has been drawn to most influential variable. Especially, there are 4 types classified by commuting distance and it became obvious that the longer the distance, the lower the safety score(under 127 m=76.9 points, Over 451 m=58.3 points). 3) As a result of investigating the influence of Safety on attending school road, Vehicle commuting speed urder 127 m as internal of school zone, and Walking and crossing convenience over 451 m as external of school zone have a lot of influence on safety cognition on school road. Therefore Safety on school road should be considering the commuting distance to school among surrounding characteristics, needed for improvement plan and program based on real safety cognition of children.

Analysis of Safety Distance and Maximum Permissible Power of Resonant Wireless Power Transfer Systems with Regard to Magnetic Field Exposure

  • Park, Young-Min;Byun, Jin-Kyu
    • Journal of Magnetics
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    • v.20 no.4
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    • pp.450-459
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    • 2015
  • In this paper, the safety distances and maximum permissible power (MPP) of resonant wireless power transfer systems are defined and derived with regard to human exposure to electromagnetic field (EMF). The definition is based on the calculated induced current density and electric field in the standard human model located between the transmitting and receiving coil. In order to avoid the adverse health effects such as stimulation of nerve tissues, the induced current and electric field must not exceed the basic restriction values specified in EMF safety guidelines. The different combinations of diameters of the coils and the distance between the two coils are investigated and their effects are analyzed. Two versions of EMF safety guidelines (ICNIRP 1998 and ICNIRP 2010) are used as bases for safety distance calculation and the difference between the two guidelines are discussed.

Hazard Distance from Hydrogen Accidents (수소가스사고의 피해범위)

  • Jo, Young-Do
    • Journal of the Korean Institute of Gas
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    • v.16 no.1
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    • pp.15-21
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    • 2012
  • An analysis was completed of the hazards distance of hydrogen accidents such as jet release, jet fire, and vapor cloud explosion(VCE) of hydrogen gas, and simplified equations have been proposed to predict the hazard distances to set up safety distance by the gas dispersion, fire, and explosion following hydrogen gas release. For a small release rate of hydrogen gas, such as from a pine-hole, the hazard distance from jet dispersion is longer than that from jet fire. The hazard distance is directly proportional to the pressure raised to a half power and to the diameter of hole and up to several tens meters. For a large release rate, such as from full bore rupture of a pipeline or a large hole of storage vessel, the hazard distance from a large jet fire is longer than that from unconfined vapor cloud explosion. The hazard distance from the fire may be up to several hundred meters. Hydrogen filling station in urban area is difficult to compliance with the safety distance criterion, if the accident scenario of large hydrogen gas release is basis for setting up the safety distance, which is minimum separation distance between the station and building. Therefore, the accident of large hydrogen gas release must be prevented by using safety devices and the safety distance may be set based on the small release rate of hydrogen gas. But if there are any possibility of large release, populated building, such as school, hospital etc, should be separated several hundred meters.

A Empirical Study on Influence of Safety on Elementary School Road Considering Commuting Distance & Mode Type (통학거리 및 수단특성을 반영한 초등학교 안전도 영향관계 실증연구)

  • Kim, Tae Ho;Kim, Seung Hyun;Lee, Soo Il
    • Journal of the Korean Society of Safety
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    • v.30 no.6
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    • pp.139-147
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    • 2015
  • This study deals with actual commuting distance and influence of risk factors depending on commuting distance and mode in order to reestablish actual commuting zone of primary school students. Data mining analysis(CHAID) was applied for this reestablishment using survey results from 6,927 primary school students in Seoul Metro. Six risk factors; convenience level of commuting path condition, convenience level of road crossing condition, vehicle speed on commuting path, segregation level between commuter and vehicle, congestion level of commuting path, and public security level and two mode; walking and cycle are considered in the analysis. As the results of CHAID analysis, commuting distance was divided into four zones; Internal Zone(0.491km under), External Zone(0.492 ~ 1.492km, 1.493 ~ 2.699km), Commutable Zone(2.70km over), and awareness level on safety is declined as commuting distance is increased. The risk factor affecting on safety is recognized differently by students depending on commuting distance and mode. For students commuting by walking, vehicle speed on commuting path and convenience level of commuting path condition are recognized as the prime risk factor within Internal Zone and Commutable Zone, respectively. For students commuting by cycle, convenience level of road crossing condition and vehicle speed on commuting path are recognized as the prime risk factor within Commutable Zone. Analysis results show that improved plan and program for commuting path for primary school students are required considering actual commuting distance and method.

Safety Distance Visualization Tool for LTE-Based UAV Positioning in Urban Areas (도심 지역 LTE 측위 기반 무인항공기 안전거리 생성 알고리즘 연구 및 시각화 도구 개발)

  • Lee, Halim;Kang, Taewon;Seo, Jiwon
    • The Journal of Advanced Navigation Technology
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    • v.23 no.5
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    • pp.408-414
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    • 2019
  • We developed a surveillance tool for collision avoidance of unmanned aerial vehicles (UAVs) in urban areas. In our tool, users can visualize the safety distance on the actual 3D map of urban area. The estimated positions of UAVs are assumed to be obtained based on the long-term evolution (LTE) signals. The safety distance is defined to include two or more signals with bias. The safety distance calculation method used in this paper enables simulation similar to the actual urban areas where signals are frequently biased due to multipath. In the simulation, the parameters were set based on the measured values, and the change of the safety distance according to the number of faulty signals was simulated. As a result, increasing the number of faulty signals led to a longer safety distance as expected.

Improvement of Damage Range Calculation for First Response to Chemical Accidents (화학사고의 일차 대응을 위한 피해영향범위 산정 개선 방안)

  • Lee, Deok Jae;Ahn, Jae-Hyun;Song, Chang Geun
    • Journal of the Korean Society of Safety
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    • v.32 no.2
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    • pp.59-65
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    • 2017
  • Calculation of the damage impact of chemical accidents is an important element in site, and the initial isolation distance and the protective action distances are significant factors in coping the chemical accident. In this study, three major cities that represent each Province were selected, and the safety distances were calculated considering regional climate conditions. The results were compared with the prescribed values in Emergency Response Guidebook. It is concluded that the regional meteorological conditions such as temperature, vapour pressure, relative humidity, wind speed, and cloud cover should be reflected in estimating the initial isolation distance and the protective action distance.

A Methodology for Determination of the Safety Distance in Chemical Plants using CFD Modeling (CFD 모델링을 이용한 화학공장의 안전거리 산정 방법론에 관한 연구)

  • Baek, Ju-Hong;Lee, Hyang-Jig;Jang, Chang Bong
    • Journal of the Korean Society of Safety
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    • v.31 no.3
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    • pp.162-167
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    • 2016
  • As the simple empirical and phenomenological model applied to the analysis of leakage and explosion of chemical substances does not regard numerous variables, such as positional density of installations and equipment, turbulence, atmospheric conditions, obstacles, and wind effects, there is a significant gap between actual accident consequence and computation. Therefore, the risk management of a chemical plant based on such a computation surely has low reliability. Since a process plant is required to have outcomes more similar to the actual outcomes to secure highly reliable safety, this study was designed to apply the CFD (computational fluid dynamics) simulation technique to analyze a virtual prediction under numerous variables of leakages and explosions very similarly to reality, in order to review the computation technique of the practical safety distance at a process plant.

A Development of Intelligent Decision System by Safely Distance of GAS Storage Tank (가스 저장탱크 안전거리의 지적 결정 시스템 개발)

  • Leem Sa-Hwan;Huh Yong-Jeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.4
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    • pp.721-726
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    • 2006
  • This paper is on intelligent decision system by safety distance of gas storage tank(IDSG). The safety distance fixed up by law is used to prevent from the injury by explosion of storage tank on the spot. However, it is not easy for a layman to decide a proper safety distance considering the size, shape and place of the storage tank. Therefore, this thesis shows the user-friendly intelligent decision system which a layman can decide the Bas related law, the size, shape and place of the storage tank by the intelligent decision, and it is to make assurance doubly sure for safety supervision on the spot. Also, the paper can make the data for the damage influence distance of overpressure by the explosion of the storage tank calculated by the scaling law of Hopkinson with the fixed distance by law, and safety range can be grasped with the graphic which is printed by the PHAST(Process Hazard Analysis Software Tool) model using this data.

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