• Steel and Composite Structures
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• 제50권3호
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• pp.265-280
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• 2024

The collapse behavior observed in single-story beam-column assembly (SSBCA) do not accurately represent the actual overall stress characteristic of multi-story frame structure (MSFS) under column loss scenario owing to ignoring the interaction action among different stories, leading to a disconnection between the anti-collapse behaviors of "components" and "overall structures", that is, the anti-collapse performance of frame structures with two different structural scales has not yet formed a combined force. This paper conducts a numerical and theoretical study to explore the difference of the collapse behaviors of the SSBCA and MSFS, and further to reveal the internal force relationships and boundary constraints at beam ends of models SSBCA and MSFS. Based on the previous experimental tests, the corresponding refined numerical simulation models were established and verified, and comparative analysis on the resistant-collapse performance was carried out, based on the validated modeling methods with considering the actual boundary constraints, and the results illustrates that the collapse behaviors of the SSBCA and MSFS is not a simple multiple relationship. Through numerical simulation and theoretical analysis, the development laws of internal force in each story beam under different boundary constraints was clarified, and the coupling relationship between the bending moment at the most unfavorable section and axial force in the composite beam of different stories of multi story frames with weld cover-plated flange connections was obtained. In addition, considering the effect of the yield performance of adjacent columns on the anti-collapse bearing capacities of the SSBCA and MSFS during the large deformation stages, the calculation formula for the equivalent axial stiffness at the beam ends of each story were provided.

• 한국재난정보학회 논문집
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• 제16권1호
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• pp.1-9
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• 2020

연구목적: 본 연구에서는 수치해석을 통한 역해석기법을 이용 현장변위예측관리기법을 보완하는 안전관리 방안에 대한 연구를 수행하였다. 연구방법: 역해석기법을 이용하여 유한요소해석 기반인 MIDAS GTS/NX 프로그램을 이용 해석을 수행하였다. 붕괴현장의 계측데이터와 변위 경향을 가능한 근접시킨 뒤, 붕괴원인을 추정 후 붕괴방지 공법을 적용하였다. 연구결과: 역해석을 수행하여 얻은 결과물중 하나인 지반정수로 붕괴원인을 추정한 결과 앵커의 자유장 길이 불충분으로 확인 되었고, 붕괴방지 공법으로 앵커의 자유장 길이를 변화시켰으며, 변위가 현저히 감소되는 것을 확인할 수 있었다. 결론: 역해석기법을 현장관리에 참고, 붕괴원인을 추정하고 합리적인 붕괴방지 대책을 제시할 경우 붕괴 사고를 줄이는데 도움이 될 것이다.

• Steel and Composite Structures
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• 제39권4호
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• pp.383-399
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• 2021

In the study, three 1:3-scale unequal span steel-concrete composite substructures with top-seat angle and double web angle connection were designed and identified as specimens GTSDWA-0.6, GTSDWA-1.0, and GTSDWA-1.4. Pseudo-static tests and refined numerical model analysis were conducted to examine the anti-progressive collapse performance of a semi-rigid steel-concrete composite substructure. The results indicated that the failure modes of the three specimens revealed that the fracture occurred in the root of the long leg of the top/seat angle in tension at the connection. With increases in the span ratio of the left and right composite beams, the bearing capacities of the composite substructures decreased, and the corresponding displacement increased. With respect to GTSDWA-0.6 and GTSDWA-1.4, the resistance due to the short composite beam corresponded to 62% and 60%, respectively, and the total resistance provided by the short composite beam exceeded that of the long composite beam. With respect to GTSDWA-1.0, the resistance due to the left and right composite beams was similar. All three specimens underwent the flexure mechanism and flexure-axial mixed mechanism stages. They resisted the external load mainly via the flexure mechanism. Moreover, the addition of stiffeners on both sides of the top and seat angles is advantageous in terms of improving the collapse resistance and ductility of unequal span composite substructures.

• 한국수산과학회지
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• 제49권5호
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• pp.594-599
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• 2016

Infection with HIV (Human immunodeficiency virus), over time, develops into acquired immunodeficiency syndrome (AIDS). The development of non-toxic and effective anti-HIV drugs is one of the most promising strategies for the treatment of AIDS. In this study, we investigated the anti-HIV-1 activity of gelatin hydrolysates from Alaska pollack skin. Gelatin hydrolysates were prepared using four enzymes (alcalase, flavourzyme, neutrase, and pronase E). Among these, the pronase E gelatin hydrolysate was found to inhibit HIV-1 infection in the human T cell-line MT4. It exhibited inhibitory activity on HIV-1_IIIB-induced cell lysis, reverse transcriptase activity, and viral p24 production at noncytotoxic concentrations. Moreover, it decreased the activation of matrix metalloproteinase-2 (MMP-2) in vitro. Because HIV infection-induced activation of MMP-2 can accelerate collagen resolution and collapse of the immune system, pronase E gelatin hydrolysate might prevent the activation of MMP-2 in cells, resulting in collagen stabilization and immune cell homeostasis consistent with anti-HIV activation. These results suggest that pronase E gelatin hydrolysate could potentially be incorporated into a novel therapeutic agent for HIV/AIDS patients.

• Composites Research
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• 제19권1호
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• pp.43-48
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• 2006

High performance fiber reinforced cement composites have better performances than traditional cement based materials, therefore, have been expected as new construction applications such as the materials for construction & bridge structure, repair and rehabilitation applications, anti-collapse applications, anti-noise applications etc. However, they have lots of the problems such as material design, fabrication method and structural analysis. Also, the most serious problems of High performance fiber reinforced cement composites have been expensive initial cost, lack of long-term exposure data. As a result, it is needed that the efforts for lowering the initial cost and accumulation of long-term exposure. There has been hardly assessment results of life cycle cost for HPFRCC in construction field, but some papers showed that total life cycle cost could be profitable if the initial cost could be reduced.

• Geomechanics and Engineering
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• 제20권1호
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• pp.43-54
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• 2020

The limit analysis and response surfaces method were combined to investigate the reliability of pressurized tunnel faces subjected to seismic force. The quasi-static method was utilized to introduce seismic force into the tunnel face. A 3D horn failure mechanism of pressurized tunnel faces subjected to seismic force was constructed. The collapse pressure of pressurized tunnel faces was solved by the kinematical approach. The limit state equation of pressurized tunnel faces was obtained according to the collapse pressure and support pressure. And then a reliability model of pressurized tunnel faces was established. The feasibility and superiority of the response surfaces method was verified by comparing with the Monte Carlo method. The influence of the mean of soil parameters and support pressure, variation coefficients, distribution type and correlation of c-φ on the reliability of pressurized tunnel faces was discussed. The reasonable safety factor and support pressure required by pressurized tunnel faces to satisfy 3 safety levels were presented. In addition, the effects of horizontal seismic force, vertical seismic force and correlation of k_h-k_v on the reliability of pressurized tunnel faces were also performed. The method of this work can give a new idea for anti-seismic design of pressurized tunnel faces.

• Advances in Traditional Medicine
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• 제7권5호
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• pp.459-465
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• 2008

The present study was undertaken to investigate the effect of in vivo administration of neem oil intra-peritoneally (i.p.) to mice bearing a progressively growing transplantable T cell lymphoma of spontaneous origin, designated as Daltons lymphoma (DL), on the tumor growth. Mice were administered various doses of neem oil mixed in groundnut oil, which was used as a diluting vehicle or for administration to control DL-bearing mice. Administration of neem oil resulted in an acceleration of tumor growth along with a reduction in the survival time of the tumor-bearing host. Neem oil administered DL-bearing mice showed an augmented apoptosis in splenocytes, bone marrow cells and thymocytes along with an inhibition in the anti-tumor functions of tumor-associated macrophages. Thus this study gives an altogether a novel information that neem oil instead of the popular belief of being anti-tumor and immunoaugmentary may in some tumor-bearing conditions, behave in an opposite way leading to an accelarated tumor progression along with a collapse of the host's anti-tumor machinery. These observations will thus have long lasting clinical significance, suggesting caution in use of neem oil for treatment of cancer.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.365-371
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• 2017

Hydrogen has potential for preventive and therapeutic applications as an antioxidant. However, micro- and macroparticles of hydrogen in water disappear easily over time. In order to eliminate reactive oxygen species (ROS) related with the aging process, we used functional water containing nanoparticle hydrogen. Nanoparticle hydrogen does not disappear easily and collapse under water after long periods of time. We used murine embryonic fibroblasts that were isolated from 12.5-day embryos of C57BL/6 mice. We investigated the ability of nanoparticle hydrogen in water to suppress hydroxyurea-induced ROS production, cytotoxicity, and the accumulation of ${\beta}-galactosidase$ (an indicator of aging), and promote cell proliferation. The accumulation of ${\beta}-galactosidase$ in the cytoplasm and the appearance of abnormal nuclei were inhibited by daily treatment of cells with hydrogen water. When the aging process was accelerated by hydroxyurea-induced oxidative stress, the effect of hydrogen water was even more remarkable. Thus, this study showed the antioxidant and anti-senescence effects of hydrogen water. Nanoparticle hydrogen water is potentially a potent anti-aging agent.

• Earthquakes and Structures
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• 제16권5호
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• pp.575-588
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• 2019

Seismic design method based on bearing capacity has been widely adopted in building codes around the world, however, damage and collapse state of structure under strong earthquake can not be reflected accurately. This paper aims to present a deformation-based seismic design method based on the research of RC component deformation index limit, which combines with the feature of Chinese building codes. In the proposed method, building performance is divided into five levels and components are classified into three types according to their importance. Five specific design approaches, namely, "Elastic Design", "Unyielding Design", "Limit Design", "Minimum Section Design" and "Deformation Assessment", are defined and used in different scenarios to prove whether the seismic performance objectives are attained. For the components which exhibit ductile failure, deformation of components under strong earthquake are obtained quantitatively in order to identify the damage state of the components. For the components which present brittle shear failure, their performance is guaranteed by bearing capacity. As a case study, seismic design of an extremely irregular twin-tower high rise building was carried out according to the proposed method. The results evidenced that the damage and anti-collapse ability of structure were estimated and controlled by both deformation and bearing capacity.

• 한국인터넷방송통신학회논문지
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• 제20권5호
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• pp.113-120
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• 2020

건설공사에 있어 산업재해라고 불리는 안전사고는 사고 발생시에는 많은 인명 피해와 재산상의 피해, 사회적으로도 큰 물의를 일으키고 있어 건설공사의 공신력 저하의 원인이 되고 있다. 최근 들어 초고층, 대심도, 다양한 용도의 복합건축물이 시공이 많아짐에 따라 건설현장의 안전사고의 위험은 계속 증가 될 수 있다. 특히, 철근콘크리트 건축물중 가장 많이 시공되는 아파트 공사는 세대구성 부분은 층별로 보가 없는 벽식 구조로 설계와 시공이 되고 저층부에서는 기둥과 보가 있는 라멘 구조로 되어 있다. 그에 따라 상부 하중을 견디기 위한 전이보 또는 전이 스라브가 라멘구조 상부에 설치되므로, 콘크리트 타설 시공시 가설재로 설치되는 시스템 동바리는 타설작업 및 양생시 붕괴 사고가 언제든 발생될 수 있다. 본 연구의 목적은 IT 융합 기술을 적용하여 콘크리트 타설시 시스템 동바리 붕괴가 발생치 않도록 하는 것을 연구 목적으로 하고 있으며, 시공 중 발생 될 수 있는 많은 변수를 각각의 사례별로 적용하여 시스템 동바리 안정성을 확인 하고 전도방지 예측 시스템의 모델을 제안 하고자 한다.