• 터널과지하공간
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• 제18권2호
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• pp.118-124
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• 2008

흙막이 구조물에 대한 발파진동 허용기준을 설정하고 10 m 이내 근거리 발파를 실측하여 흙막이 구조물에 전달되는 진동규모를 확인하였다. 또 시험발파 계측데이터로부터 발파작업이 흙막이 구조물과 배면지반에 미치는 영향을 평가하였다. 연구결과 $0.5{\sim}2.0kg$ 범위의 발파작업은 흙막이 구조물과 배면지반에 거의 영향을 미치지 않는 것으로 분석되었으나 발파압력에 의한 암반블록의 이동 영향을 고려하여 최소저항선의 2배 정도를 이격하여 발파할 것을 추천한다.

• 콘크리트학회논문집
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• 제26권6호
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• pp.715-722
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• 2014

본 논문에서는 철근콘크리트 코어 구조물의 내부폭발 효과를 폭발이나 충격해석에 특화되어 있는 하이드로코드인 Ansys Autodyn을 이용하여 조사하였다. 내부폭발의 경우 폭발하중의 반사효과로 인해 더욱 큰 파괴를 일으킬 수 있다. 그러므로, 본 논문에서는 UFC 3-340-02 를 사용하여 내부 폭발현상을 입증하였다. 추가적으로 Autodyn을 사용한 해석에 관하여 UFC에서 예제로 제시하는 폭발하중의 반사에 관한 실험 결과를 비교하여 Autodyn이 내부폭발 효과를 해석하는데 적합함을 증명하였다. 나아가, 초고층빌딩에서 가장 중요한 부분 중의 하나의 코어 구조의 붕괴메커니즘을 Autodyn을 사용하여 해석하였다. 내부폭발이 코어에 충격을 가할 때, 코어는 모서리와 폭발 정면 부분이 대부분 피해를 입었다. 그러므로, 코어 벽체가 피해를 입게 된다면 코어 구조물의 연쇄붕괴가 발생할 수 있다.

• Advances in concrete construction
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• 제5권5호
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• pp.493-512
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• 2017

Blast loads may considerably affect the response of structures. In previous years, before computer analysis programs, the parameters of blast effects were calculated with empirical methods, consequently some researchers had proposed equations to find out the phenomenon. In recent year's computer analysis programs have developed already, so detailed solutions can be made numerically. This paper describes the blasting response of the structures using numerical and empirical methods. For the purpose, a reinforced concrete retaining wall is modelled using ANSYS Workbench software, and the model is imported to ANSYS AUTODYN software to perform explicit analyses. In AUTDYN software, a sum of TNT explosive is defined 5,5 m away from the wall and solution is done. Numerical results are compared with those of obtained from empirical equations. Similar study is also considered for equal explosive which is the 4 m away from the wall. The results are represented by graphics and contour diagrams of such as displacements and pressures. The results showed that distance of explosive away from the wall is highly affected the structural response of it.

• 한국지열·수열에너지학회논문집
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• 제18권3호
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• pp.7-18
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• 2022

Secondary batteries used in electric vehicles have a potential risk of ignition and explosion. Various safety measures are being taken to prevent these risks. A numerical study was performed using a computational fluid dynamics code on the cases where pressure relief vents that can reduce the blast overpressures of batteries were installed in the through-compression test room, short-circuit drop test room, combustion test room, and immersion test room in facilities rleated to battery used in electric vehicles. This study was conducted using the weight of TNT equivalent to the energy release from the battery, where the the thermal runaway energy was set to 324,000 kJ for the capacity of the lithium-ion battery was 90 kWh and the state of charge (SOC) of the battery of 100%. The explosion energy of TNT (△H_TNT) generally has a range of 4,437 to 4,765 kJ/kg, and a value of 4,500 kJ/kg was thus used in this study. The dimensionless explosion efficiency coefficient was defined as 15% assuming the most unfavorable condition, and the TNT equivalent mass was calculated to be 11 kg. The internal explosion generated in a test room shows the very complex propagation behavior of blast waves. The shock wave generated after the explosion creates reflected shock waves on all inner surfaces. If the internally reflected shock waves are not effectively released to the outside, the overpressures inside are increased or maintained due to the continuous reflection and superposition from the inside for a long time. Blast simulations for internal explosion targeting four test rooms with pressure relief vents installed were herein conducted. It was found that that the maximum blast overpressure of 34.69 bar occurred on the rear wall of the immersion test room, and the smallest blast overpressure was calculated to be 3.58 bar on the side wall of the short-circuit drop test room.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 추계학술대회 및 정기총회
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• pp.23-23
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• 2015

Rice blast disease caused by M. oryzae is the most devastating fungal disease in rice. During the infection process, M. oryzae secretes a large number of glycosyl hydrolase (GH) proteins into the apoplast to digest host cell wall and assist fungal ingress into host tissues. In this study, we identified a novel M. oryze arabinofuranosidase B (MoAbfB) which is secreted during fungal infection. Live-cell imaging exhibited that fluorescent labeled MoAbfB was highly accumulated in fungal invasive structures such as appressorium, tips of penetration peg, biotrophic interfacial complex (BIC), as well as invasive hyphal tip. Deletion of MoAbfB mutants extended biotrophic phase followed by enhanced disease severity, whereas, over-expression of OsMoAbfB mutant induced rapid defense responses and enhanced rice resistance to M. oryzae infection. Furthermore, exogenous treatment of MoAbfB protein showed inhibition of fungal infection via priming of defense gene expression. We later found that the extract of MoAbfB degraded rice cell wall fragments could also induce host defense activation, suggesting that not MoAbfB itself but oligosaccharides (OGs) derived from MoAbfB dissolved rice cell wall elicited rice innate immunity.

• Structural Engineering and Mechanics
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• 제51권1호
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• pp.141-162
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• 2014

The paper focuses on the dynamic response of a blast-invested glass-steel curtain wall supported by single-way pretensioned cables. In order to mitigate the critical components of the façade from severe structural damage, an innovative system able to absorb and dissipate part of the blast-induced stresses in the critical façade components is proposed. To improve the blast reliability of the studied glazing system, specifically, rigid-plastic and elastoplastic devices are introduced at the base and at the top of the vertical bearing cables. Several combinations and mechanical calibrations of these devices are numerically investigated and the most structurally and economically advantageous solution is identified. In conclusion, a simple analytical formulation totally derived from energetic considerations is also suggested for a preliminary estimation of the maximum dynamic effects in single-way cable-supported façades subjected to high-level blast loads.

• Structural Engineering and Mechanics
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• 제75권5호
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• pp.607-620
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• 2020

A numerical study is carried out to assess the dynamic response and damage level of one- and two-way reinforced concrete (RC) panels subjected to explosive loads by using finite element LS-DYNA software. The precision of the numerical models is validated with the previous experimental test. The calibrated models are used to conduct a series of parametric studies to evaluate the effects of panel wall dimensions, concrete strength, and steel reinforcement ratio on the blast-resistant capacity of the panel under various magnitudes of blast load. The results are used to develop pressure-impulse (P-I) diagrams corresponding to the damage levels defined according to UFC-3-340-02 manual. Empirical equations are proposed to easily construct the P-I diagrams of RC panels that can be efficiently used to assess its safety level against blast loads.

• 콘크리트학회논문집
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• 제19권2호
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• pp.241-250
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• 2007

폭발하중을 받는 콘크리트 구조물을 섬유 복합재 등의 보강 재료를 사용하여 보강하는 경우에는 강성 증가와 함께 적절한 연성을 확보할 수 있어야 한다. 그러나, 폭발하중을 받는 구조물의 설계 및 해석에 일반적으로 사용되는 기존의 근사적이며 단순화 모델은 보강 재료에 대한 효과를 정확히 반영할 수 없을 뿐 아니라 해석 결과의 정확성 및 신뢰성에 문제가 제기되어왔다. 또한, 동적 하중에 대한 콘크리트와 철근의 응답은 정적 하중에 대한 응답과 상이하기 때문에 기존의 정적, 준정적하에서 정의된 재료물성값들을 폭발하중에 대한 응답 계산에 사용하는 것은 부적절하다. 따라서, 본 연구에서는 명시적(explicit) 해석 프로그램인 LS-DYNA를 사용하여 매우 빠른 재하속도를 갖는 폭발하중에 대하여 강도 증진 및 변형률 속도 효과가 반영된 재료 모델을 포함하고 있는 정밀 HFPB(high fidelity physics based) 유한요소해석 기법을 제시하였다. 제시된 해석적 기법을 통하여 탄소섬유 복합재와 유리섬유 복합재를 사용하여 보강된 콘크리트 벽체의 폭발하중에 대한 거동을 해석하였으며, 이를 보강하지 않은 벽체의 해석 결과와 비교함으로써 보강 성능 분석을 실시하였다. 해석 결과 보강에 따른 최대 처짐이 약 $26{\sim}28%$ 감소하는 보강 성능을 확인하였으며, 제안된 해석 기법이 보강 재료와 보강 기법의 유효성을 평가하는데 효과적으로 적용할 수 있을 것으로 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.269-272
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• 2008

매우 짧은 시간동안 큰 압력을 유발하는 폭발하중은 지형적인 조건 및 대기조건, 장약량과 구조물의 위치 및 형상에 따라 상이하게 발생된다. 그러므로 본 연구에서는 콘크리트 구조물에 작용하는 정밀한 폭발하중의 전파해석을 위해, Arbitrary Lagrangian-Eulerian기법을 적용한 대기 및 폭발물의 모델을 통해 복합적인 폭발파를 구현하고 구조물의 동적재료 특성을 고려하여 대기-구조물의 통합모델 해석기법을 제안하였다. 또한 대기-구조물의 통합모델 해석기법의 검증을 위하여 폭발하중을 받는 철근콘크리트 구조물의 폭발실험결과와 비교함으로써 제안된 해석기법의 타당성을 검증하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.220-223
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• 2008

A test facility to measure the performance of a KM(Kick Motor) is constructed, and prediction of blast wave propagation over the facility is performed to check if the safety of test personnel in MCC(Main Control Center) can be guaranteed even for the most severe explosion. Assuming that the initial explosion energy is contained in a sphere under the pressure of 500, 1000, 1500 psi, respectively, the radius of the sphere is determined for each pressure to set the mass of contained explosion gas to 35 kg. The material properties of explosion gas are set to be the ones of KM propellant combustion gas under normal condition. To reduce the effort and time required for a complex three-dimensional modeling, the flowfield is approximated to axismmetry. Calculations are performed for all three initial pressure conditions, and the analysis of the result is given for 1500 psi which is expected to be the worst case. The maximum pressure is 3.5 psig while the minimum pressure is -1.2 psig on the outer wall of MCC, and the maximum pressure difference between the inner and outer walls of protection wall amounts to 3.0 psi.