• Structural Engineering and Mechanics
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• 제61권3호
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• pp.419-426
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• 2017

Recently, the transportation of dangerous explosive goods is increasing, which makes vehicle blasting accidents a potential threat for the safety of bridge structures. In addition, blasting accidents happen more easily when earthquake occurs. Excessive dynamic response of bridges under extreme loads may cause local member damage, serviceability issues, or even failure of the whole structure. In this paper, a new explosion-proof and aseismic system is proposed including cable support damping bearing and steel-fiber reinforced concrete based on the existing researches. Then, considering one 40m-span simply supported concrete T-bridge as the prototype, through scale model test and numerical simulation, the dynamic response of the bridge under three conditions including only earthquake, only blast load and the combination of the two extreme loads is obtained and the applicability of this explosion-proof and aseismic system is explored. Results of the study show that this explosion-proof and aseismic system has good adaptability to seism and blast load at different level. The reducing vibration isolation efficiency of cable support damping bearing is pretty high. Increasing cables does not affect the good shock-absorption performance of the original bearing. The new system is good at shock absorption and displacement limitation. It works well in reducing the vertical dynamic response of beam body, and could limit the relative displacement between main girder and capping beam in different orientation so as to solve the problem of beam falling. The study also shows that the enhancement of steel fibers in concrete could significantly improve the blast resistance of main beam. Results of this paper can be used in the process of antiknock design, and provide strong theoretical basis for comprehensive protection and support of girder bridges.

• 한국초전도ㆍ저온공학회논문지
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• 제15권4호
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• pp.53-58
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• 2013

KSTAR in-vessel cryo-pump has been installed in the vacuum vessel top and bottom side with up-down symmetry for the better plasma density control in the D-shape H-mode. The cryogenic helium lines of the in-vessel cryo-pump are located at the vertical positions from the vacuum vessel torus center 2,000 mm. The inductive electrical potential has been optimized to reduce risk of electrical breakdown during plasma disruption. In-vessel cryo-pump consists of three parts of coaxial circular shape components; cryo-panel, thermal shield and particle shield. The cryo-panel is cooled down to below 4.5 K. The cryo-panel and thermal shields were made by Inconel 625 tube for higher mechanical strength. The thermal shields and their cooling tubes were annealed in air environment to improve the thermal radiation emissivity on the surface. Surface of cryo-panel was electro-polished to minimize the thermal radiation heat load. The in-vessel cryo-pump was pre-assembled on a test bed in 180 degree segment base. The leak test was carried out after the thermal shock between room temperature to $LN_2$ one before installing them into vacuum vessel. Two segments were welded together in the vacuum vessel and final leak test was performed after the thermal shock. Commissioning of the in-vessel cryo-pump was carried out using a temporary liquid helium supply system.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.5779-5785
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• 2015

The present study was designed to investigate cholangiocarcinoma (CCA) antibodies in hamster serum. Hamster CCA cell lines were processed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. A candidate biomarker was confirmed by immunoprecipitation and western blot, and was further analyzed using ELISA and sera from normal control hamsters, hamsters with opisthorchiasis and hamsters with various stages of CCA, as well as from CCA patients and healthy individuals. One candidate marker was identified as $HSP90{\alpha}$, as indicated by a high level of anti-$HSP90{\alpha}$ in hamster CCA sera. It was found that the levels of anti-$HSP90{\alpha}$ were specifically elevated in the sera of hamsters with CCA compared with other groups and progressively increased with the clinical stage. At the cut-off point of 0.4850 on the receiver operating characteristic curve, anti-$HSP90{\alpha}$ could discriminate CCA from healthy control groups with a sensitivity of 76.2%, specificity of 71.4% and total accuracy 75.5%. In the present study, we have shown that anti-$HSP90{\alpha}$ may be a potential useful serum biomarker to discriminate CCA cases from healthy persons.

• 한국가축번식학회지
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• 제26권4호
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• pp.311-320
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• 2002

The objective of this study was to assess the developmental potential in vitro produced embryos frozen-thawed with the various containers, and also examined expression and localization of heat shock protein 70 at these embryos. For the vitrification, 2-cell, 8-cell and blastocyst stage embryos produced by in vitro fertilization (IVF) and nuclear transfer (NT) were exposed the ethylene glycol 5.5 M freezing solution (EC 5.5) for 30 sec, loaded on each containers such EM grid, straw and cryo-loop, and then immediately plunged into liquid nitrogen. Thawed embryos were serially diluted in sucrose solution, each for 1 min. and cultured in CRI-aa medium. Survival rates of the vitrification production were assessed by re-expanded, hatched blastocysts. There were no differences in the survival rates of IVF using EM grid and cryo-loop. However, survival rates by straw were relatively lower than other containers. The use of cryo-loop resulted in only survival of nuclear transferred embryos (43.7%). Also, there embryos after IVF or NT were analysed by semi-quantitive reverse transcription-polymerase chain reaction (RT- PCR) methods for hsp 70 mRNA expression. Results revealed the expression of hsp 70 mRNh were higher thawed embryos than control embryos. Immunocytochemistry used to localize the hsp 70 protein in embryos. Two and 8-cell embryos derived under control condition was evenly distributed in the cytoplasm but appeared as aggregates in some frozen-thawed embryos. However, in the control, blastocysts displayed aggregate signal while Hsp70 in frozen-thawed blastocysts appeared to be more uniform In distribution. Therefore, this result suggests that the exploiting Hsp 70 in the early embryos may be role for protection of stress condition for increase viability of embryos within IVF, NT and there frozen-thawed embryos.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.671-686
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• 2004

The shock-induced combustion ramjet (shcramjet) is a hypersonic airbreathing propulsion concept which over-comes the drawbacks of the long, massive combustors present in the scramjet by using a standing oblique detonation wave (a coupled shock-combustion front) as a means of nearly instantaneous heat addition. A novel shcramjet combustor design that makes use of wedge-shaped flameholders to avoid detonation wave-wall interactions is proposed and analyzed with computational fluid dynamics (CFD) simulations in this study. The laminar, two-dimensional Navier-Stokes equations coupled with a non-equilibrium hydrogen-air combustion model based on chemical kinetics are used to represent the physical system. The equations are solved with the WARP (window-allocatable resolver for propulsion) CFD code (see: Parent, B. and Sislian, J. P., “The Use of Domain Decomposition in Accelerating the Convergence of Quasihyperbolic Systems”, J. of Comp. Physics, Vol. 179, No. 1,2002, pages 140-169). The solver was validated with experimental results found in the literature. A series of steady-state numerical simulations was conducted using WARP and it was deter-mined by means of thrust potential calculations that this combustor design is a viable one for shcramjet propulsion: assuming a shcramjet flight Mach number of twelve at an altitude of 36,000 m, the geometrical dimensions used for the combustor give rise to an operational range for combustor inlet Mach numbers between six and eight. Different shcramjet flight Mach numbers would require different combustor dimensions and hence a variable geometry system in or-der to be viable.

• 한국가스학회지
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• 제25권1호
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• pp.40-47
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• 2021

본 연구에서는 화재폭발 사고의 원인 규명을 위하여 다양한 시험 장비를 사용하여 유기과산화물의 일종인 터셔리부틸퍼옥시말레이트(TBPM)의 분해 및 폭발 위험성을 조사하였다. 시차주사열량(DSC) 분석결과, TBPM의 순간동력밀도(IPD)는 26,401 kW/ml로서 NFPA 반응성지수(Nr)가 4로 분류되었다. 또한 발열량과 개시온도 측정값을 이용한 폭발전달성(EP)과 충격감도(SS)는 양의 값을 나타내며 위험성이 있는 것으로 예측되었으며, 평가 장비를 활용한 실험적 결과로부터 충격감도와 마찰감도는 각각 4급 및 5급으로 평가되었다. 압력용기시험에서는 USA-PVT No.가 4로 분류되어 자기반응성물질에 해당되는 것으로 나타났다. 연소속도에 대한 조사 결과로부터 TBPM은 167 mm/sec의 연소속도를 나타내며 인화성고체 분류2에 포함되는 것으로 평가되었다.

• 이베로아메리카
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• 제23권2호
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• pp.273-307
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• 2021

The covid 19 pandemic led to an economic collapse and multiple impacts upon Argentina's labour dynamics. As well as in other parts of the region, falls in employment rates (both due to an increase in unemployment and significant withdrawals from the labour force) were combined with wage reductions for those who were able to keep their jobs. Thus, two important processes for the labour market complimented each other: a structural shock associated with a tasks automation as a reorganisation and substitution of factors, with a cyclical recession caused by the pandemic. The international experience shows the amplifying impact the latter has on the former, generating long-term consequences mainly in routine-intensive jobs. However, the knowledge-intensive services sector appears to be the most capable of cushioning the recessionary shock (both in terms of wages and labour absorption), even with nuances within the sector depending on the extent of the shutdown measures and its capability to switch to remote work. Finally, the task approach is decisive in capturing the ability to adapt both the cyclical and structural processes, absorbing a large part of the explanatory potential that sectoral classifications tend to bring about.

• 대한치과기공학회지
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• 제46권2호
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• pp.21-27
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• 2024

Purpose: This study aimed to analyze the stress distribution and deformation in implant abutments made from titanium (Ti-6Al-4V), zirconia, and polyetheretherketone (PEEK), including their screws and fixtures, under various loading conditions using finite element analysis (FEA). Methods: Three-dimensional models of the mandible with implant abutments were created using Siemens NX software (NX10.0.0.24, Siemens). FEA was conducted using Abaqus to simulate occlusal loads and assess stress distribution and deformation. Material properties such as Young's modulus and Poisson's ratio were assigned to each component based on literature and experimental data. Results: The FEA results revealed distinct stress distribution patterns among the materials. Titanium alloy abutments exhibited the highest stress resistance and the most uniform stress distribution, making them highly suitable for long-term stability. Zirconia abutments showed strong mechanical properties with higher stress concentration, indicating potential vulnerability to fracture despite their aesthetic advantages. PEEK abutments demonstrated the least stress resistance and higher deformation compared to other abutment materials, but offered superior shock absorption, though they posed a higher risk of mechanical failure under high load conditions. Conclusion: The study emphasizes the importance of selecting appropriate materials for dental implants. Titanium offers durability and uniform stress distribution, making it highly suitable for long-term stability. Zirconia provides aesthetic benefits but has a higher risk of fracture compared to titanium. PEEK excels in shock absorption but has a higher risk of mechanical failure compared to both titanium and zirconia. These insights can guide improved implant designs and material choices for various clinical needs.

• 미생물학회지
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• 제34권3호
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• pp.154-161
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• 1998

자연미생물, KP964에 luxAB 유전자를 주입하여 발광기능을 부여함으로써 그들의 발광정도가 스트레스에 대한 적응, 생존 및 활성도를 나타내는 색인이 될 수 있는가, 그리고 특히 non-culturable but viable(NCBV) 상태로 존재하는 미생물의 활성에 대한 정보를 제공할 수 있는가를 알아보았다. 영양결핍조건 하에서 그들의 총 세균수, 배양가능세균(colony-forming-unit; CFU)수, viable cell 수, 그리고 발광정도(relative light unit; RLU)의 변화를 조사하였다. 형광현미경으로 확인된 총 수는 변화가 없었으며, 첨가된 yeast extract에 의해 성장하는 viable cell 수는 완만하게 감소하였으나 CFU 수는 급격히 줄어들어 37일 째 이후에는 탐지한계 이하로 감소하였다. RLU의 경우, 처음 7일의 영양결핍동안 0.016%까지 감소하였으며, 그 이후에는 탐지한계수준 이하로 검출되었다. 아울러 스트레스를 받는 4시간 동안 CFU수와 RLU의 관계를 알아보기 위하여 발광 KP964 균주에게 독성유해물질, acid shock, osmotic shocks를 접촉시킨 후 시간별로 CFU와 RLU를 측정한 결과, KP964 CFU 당 RLU는 9.1-26% 까지 감소하였다. 이는 스트레스의 종류에 따라 접촉시간이 길수록 CFU 당 나오는 빛의 양이 줄어듬을 보인 것이다. 이러한 결과는 영양결핍조건 시 RLU의 감소율이 CFU의 감소율보다 더 크며 영양결핍 이외의 다른 스트레스 조건 하에서도 RLU의 감소율과 CFU의 감소율의 연관성을 찾을 수 없음을 보이므로, 발하는 빛의 정량만으로는 NCBV 상태는 물론 배양가능한 세균의 양이나 활성을 나타내지 못하는 듯 하였다. 그러나 스트레스를 받은 KP964의 활성 정도와 잠재발광능력과의 관계는 좋은 연관성을 보여주었다. 즉, p-xylene, hypo-osmotic stress, 또는 영양결핍에 노출된 세균으로부터 각 스트레스를 제거하였을 시 나타나는 발광증가 유형을 조사하였는데, 증가가 시작하기까지의 lag period는 각각 32, 26, 22분으로 나타났다. 즉 미생물에 강력한 스트레스로 작용한 경우일수록 lag time이 길고, 또한 발광의 증가율이 느리며 도달하는 최대 RLU값도 낮음이 관찰되었다. 따라서 스트레스 하의 세균으로부터 직접적인 RLU의 측정보다는 이들이 스트레스 조건으로부터 재성장 또는 소생되는 과정에서의 잠재 발광능력의 분석이 자연세균의 적응, 활성 및 생존의 정도를 나타내주었다.

• 생명과학회지
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• 제19권5호
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• pp.598-606
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• 2009

본 연구는 저산소증에서 반하가 대뇌신경세포에 미치는 영향을 알아보기 위하여 $E_18$의 배양 흰쥐 대뇌신경세포를 반하로 전처리한 후, LDH assay와 tryphan blue 염색으로 세포 생존율을 측정하였고, $H_2DCF-DA$, JC-1 염색으로 MMP, ROS 및 RNS 변화를 조사하였다. 이에 반하는 저산소증으로 유발된 대뇌신경세포를 2.5 ${\mu}g/ml$까지 농도의존적으로 세포 생존률을 증가시켰으며, 시간에 따른 생존율을 살펴보면 저산소증 유발 후 1 시간에는 별 차이를 보이지 않았지만 3 일, 5 일 후에는 각각 10.2%, 17.8%로 매우 유의한 증가를 보였다. 저산소증에서 반하가 MMP에 미치는 영향을 보기 위해 저산소증 유발직전과 유발 후 1 일, 3 일, 5 일에 JC-1으로 염색하고 미토콘드리아의 염색강도를 측정한 결과 적색형광은 실험군에서 전반적으로 대조군에 비하여 강하게 염색되는 미토콘드리아의 비율을 증가시킨 반면 녹색형광은 대조군과 뚜렷한 차이를 보이지 않았다. 즉 반하가 저산소증으로 유발된 MMP의 소실을 감소시킴을 알 수 있다. 또한 반하는 전반적으로 $H_2DCF-DA$에 염색되는 세포 비율을 현저하게 낮추는 것으로 나타나 저산소증으로 유발된 ROS 및 RNS의 생성을 유의성 있게 감소시켰다. 따라서 반하는 저산소증에서 ROS의 생성을 억제하고 MMP의 소실을 막아 세포의 에너지고갈을 방지함으로서 신경세포를 보호하는 것으로 이해된다.