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전단마찰 및 스트럿-타이 모델을 이용한 철근콘크리트 코벨의 전단강도 예측
윤영묵(Yun Young Mook),김병헌(Kim Byung Hun),이원석(Lee Won Seok),정찬핵(Jeong Chan Haek) 대한토목학회 2007 대한토목학회논문집 A Vol.27 No.2A
철근콘크리트 코벨은 주로 보나 거더를 지지하기 위하여 프리캐스트 콘크리트 구조물의 건설에 널리 사용되고 있으며, 이러한 프리캐스트 콘크리트 구조물이 많이 보급됨에 따라 철근콘크리트 코벨의 설계는 점점 중요시되고 있다. 철근콘크리트 코벨은 주인장 철근의 항복에 의한 파괴, 콘크리트 스트럿의 압축에 의한 파괴, 하중의 기둥면을 따라서 발생하는 전단파괴, 그리고 하중판 아래의 지압파괴 등 여러 가지 형상의 파괴형태를 보이나, 이러한 파괴메카니즘을 예측하여 철근콘크리트 코벨을 설계하는 것은 쉽지 않다. 본 연구에서는 전단마찰 모델에 근거한 ACI 318-05 설계기준과 트러스 모델에 근거한 연화 및 비선형 스트럿-타이 모델 방법의 특정적인 사항을 소개하였고 이들 방법을 이용하여 파괴실험이 수행된 19개의 일반강도 및 고강도 철근콘크리트 코벨의 전단강도를 평가하였다. 또한 평가결과의 비교분석과 각 방법의 장단점 분석을 통하여 해석 및 실무설계 적용 시의 적합성을 검토하였다. The reinforced concrete corbels are used extensively in precast concrete constructions to support primary beams and girders. Because of the prevalence of precast concrete, the design of corbels has become increasingly important. The reinforced concrete corbels tend to fail in several modes. The most common of which are the yielding of main tensile reinforcement, the crushing or splitting of the compression strut, the shearing failure along the column face, and the localized bearing failure under the loading plate. Because of these various failure modes, the rational analysis and design of reinforced concrete corbels are difficult. In this study, the characteristic features of the currently used analysis and design methods of reinforced concrete corbels, i.e, the ACI 318-05 design code implementing the shear-friction model and the softened and nonlinear strut-tie model approaches implementing the truss model, are introduced. In addition, the appropriateness of each model is examined through the strength evaluation of 19 normal and high strength reinforced concrete corbels tested to failure.
단순지지 RC 깊은 보 부정정 스트럿-타이 모델의 하중분배율 : (Ⅱ) 적합성 평가
김병헌(Kim Byung Hun),정찬핵(Jeung Chan Haek),윤영묵(Yun Young Mook) 대한토목학회 2008 대한토목학회논문집 A Vol.28 No.2A
본 논문에서는 전편논문에서 제안한 부정정 스트럿-타이 모델 및 하중분배율 결정식을 ACI 318-05 스트럿-타이 모델 설계기준에 적용하여 파괴실험이 수행된 229개 단순지지 철근콘크리트 깊은 보의 극한강도를 평가하였다. 또한 229개 깊은 보의 극한강도를 실험식, 실험 전단강도모델에 기초한 설계기준, 이론 전단강도모델에 기초한 설계기준, 그리고 현 스트럿-타이모델 설계기준 등으로 평가하고, 그 결과를 본 연구의 방법에 의한 결과와 비교분석하여 본 연구에서 제안한 방법의 적합성을 검증하였다. In this study, the ultimate strengths of 229 simply supported reinforced concrete deep beams tested to shear failure were evaluated by the ACI 318-05's strut-tie model approach implemented with the presented indeterminate strut-tie model and its load distribution ratio. The ultimate strengths of the deep beams were also estimated by the experimental shear equations, design codes that were based on experimental and theoretical shear strength models, and current strut-tie model design codes. The validity of the present strut-tie model and its load distribution ratio was examined through the comparison of the strength analysis results classified according to the prime design variables of the shear span-to-effective depth ratio, flexural reinforcement ratio, and compressive strength of concrete.
Jung, Jae Cheon,Kim, Haek Yun The Korean Society of Systems Engineering 2020 시스템엔지니어링학술지 Vol.16 No.1
This paper aims to develop an optimized inventory management method for safety critical Instrument and Control (I&C) components. In this regard, the paper focuses on estimating the consumption rate of I&C components using demand forecasting methods. The target component for this paper is the Foxboro SPEC-200 controller. This component was chosen because it has highest consumption rate among the safety critical I&C components in Korean OPR-1000 NPPs. Three analytical methods were chosen in order to develop the demand forecasting methods; Poisson, Generalized Linear Model (GLM) and Bootstrapping. The results show that the GLM gives better accuracy than the other analytical methods. This is because the GLM considers the maintenance level of the component by discriminating between corrective and preventive.
Song Yeon-Hwa,Park Se-Ah,Yun Su-Jin,Yang Hye-Jin,Yoon A-Young,Kim Haek-Won 한국발생생물학회 2011 발생과 생식 Vol.15 No.4
Human eyelid adipose-derived stem cells (hEAs) and amniotic mesenchymal stem cells (hAMs) are very valuable sources for the cell therapeutics. Both types of cells have a great proliferating ability in vitro and a multipotency to differentiate into adipocytes, osteoblasts and chondrocytes. In the present study, we evaluated their stem cell characteristics after long-time cryopreservation for 6, 12 and 24 months. When frozen-thawed cells were cultivated in vitro, their cumulative cell number and doubling time were similar to freshly prepared cells. Also they expressed stem cell-related genes of SCF, NANOG, OCT4, and TERT, ectoderm-related genes of NCAM and FGF5, mesoderm/endoderm-related genes of CK18 and VIM, and immune-related genes of HLA-ABC and 2M. Following differentiation culture in appropriate culture media for 2-3 weeks, both types of cells exhibited well differentiation into adipocyte, osteoblast, and chondrocyte, as revealed by adipogenic, osteogenic or chondrogenic-specific staining and related genes, respectively. In conclusion, even after long-term storage hEAs and hAMs could maintain their stem cell characteristics, suggesting that they might be suitable for clinical application based on stem cell therapy.
Design and Manufacture of Robotic Exoskeleton Hands Using 3-D Printer
Jong-Hun Choe,Seong-Hyeon Jo,Suk-Hyun Seo,Won-Hoe Kim,Ji-Eum Hyun,Hong-Kyu Lee,Yun-Haek Kim,Se-Ho Park 한국공학교육학회 2014 공학교육연구 Vol.17 No.4
Robotic exoskeletons are kind of wearable robots enabling operators to amplify the force. There are several possible applications in plenty of options: to put very heavy products into right positions for assemblies, to rescue people from natural disasters, and to work for medical rehabilitation etc. In this study, the exoskeleton hands were designed and fabricated using 3-D printer. It would be the good case of application of 3-D printer to design and fabricate the exoskeleton hands.
Design and Manufacture of Robotic Exoskeleton Hands Using 3-D Printer
Choe, Jong-Hun,Jo, Seong-Hyeon,Seo, Suk-Hyun,Kim, Won-Hoe,Hyun, Ji-Eum,Lee, Hong-Kyu,Kim, Yun-Haek,Park, Se-Ho Korean Society for Engineering Education 2014 공학교육연구 Vol.17 No.4
Robotic exoskeletons are kind of wearable robots enabling operators to amplify the force. There are several possible applications in plenty of options: to put very heavy products into right positions for assemblies, to rescue people from natural disasters, and to work for medical rehabilitation etc. In this study, the exoskeleton hands were designed and fabricated using 3-D printer. It would be the good case of application of 3-D printer to design and fabricate the exoskeleton hands.