• Title/Summary/Keyword: Static Yield Shear Stress

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Production of Bacterial Cellulose by Gluconacetobacter hansenii PJK Isolated from Rotten Apple

  • Park, Joong-Kon;Park, Youn-Hee;Jung, Jae-Yong
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.8 no.2
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    • pp.83-88
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    • 2003
  • A cellulose-producing strain isolated from rotten apples was identified as Gluconacetobacter hansenii based on its physiological properties and the 16S rDNA complete sequencing method, and specifically named Gluconacetobacter hansenii PJK. The amount of bacterial cellulose (BC) produced by G. hansenii PJK in a shaking incubator was 1.5 times higher than that produced in a static culture. The addition of ethanol to the medium during cultivation enhanced the productivity of bacterial cellulose, plus the supplementation of 1% ethanol into the culture medium made the produced BC aggregate into a big lump and thus protected the bacterial-cellulose-producing G. hansenii PJK cells in the shear stress field from being converted into non-cellulose-producing (Cel) mutants. Cells subcultured three times in a medium containing ethanol retained their ability to produce BC without any loss in the production yield.

자동차용 구조접착접합이음의 응력해석과 강도평가에 관한 연구

  • Yu, Yeong-Chul;Oh, Seung-Kyu;Yi, Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.4
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    • pp.905-915
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    • 1998
  • Static tensile tests using adhesive-bonded single-lap joints of aluminum alloy were conducted to investigate the effect of geometric factor, overlap length, adherend thickness, adhesive thickness and material composition of adherend/adhesive on the strength of adhesive joint. The average applied shear stress at joint fracture decreased with increasing lap length. However increasing the adherend thickness resulted in a higher joint strength. Higher yield strength of adherend and lower elastic modulus of adhesive is advantageous to the adhesive joint. Newly proposed modified joint factor could be well evaluated the influence of lap length, adherend thickness and adhesive thickness on the bond strength for adhesive joints.

Active Tension Control Using an ER Brake Actuator (ER브레이크 작동기를 이용한 능동 장력 제어)

  • Park, S.B.;Kim, G.W.;Cheong, C.C.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.8
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    • pp.102-111
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    • 1996
  • This paper presents a proof-of-concept investigation on an active tension control using an ER (electro-rheological) brake actuator. Firstly, an ERF (electro-rheological fluid) which has an inherent reversible feature from Newtonian fluid to Bingham fluid upon applying an electric field is composed, and its property is tested to obtain intrinsic parameters of the Bingham model. An appropriate size of the ER brake is manufactured on the basis of the Bingham model, and dynamic characteristics of the brake are experimentally identified. After formulating a governing equation of motion of the tension control system, a sliding mode controller is designed to achieve a certain desired level of tension. Both simulation and experimental works are undertaken in order to demonstrate the efficiency and feasibility of the proposed active tension control method.

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Evaluation of Moment Resisting Post-Base Connection Using Multi-directional Connector (다방향 접합철물 삽입형 기둥-기초 접합부 모멘트 저항성능평가)

  • Kim, Keon-Ho;Lee, Sang-Joon
    • Journal of the Korea Furniture Society
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    • v.25 no.4
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    • pp.331-337
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    • 2014
  • The purpose of this paper is to evaluate the moment resistance of glulam post-to-base connections by applying quasi-static cyclic loads. The connectors consisted of inserted plates and drifted pins according to the load direction. The connection types employed in this study were total three including two unidirectional types (H, V) and the multi-directional type (M). The moment resistance of 8 mm-plate M-type is compared to 6 mm plate. Total four types of Post-to-base connection are prepared and tested under pseudo-static reversed cyclic loading. Test results showed that the yield moment of multi-directional connection is about 2 times higher than that uni-directional connections. The ductility ratio of multi-directional connection determined by EEEP was higher that that of uni-directional connection. It was becoming higher as the thickness of plate is increased. The Finite Element Analysis was conducted to estimate the stress distribution behavior of tested connections. Results showed the failure of multi-directional type were caused by the split of pined hole and the shear failure of lifted part of post.

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A novel two-dimensional approach to modelling functionally graded beams resting on a soil medium

  • Chegenizadeh, Amin;Ghadimi, Behzad;Nikraz, Hamid;Simsek, Mesut
    • Structural Engineering and Mechanics
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    • v.51 no.5
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    • pp.727-741
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    • 2014
  • The functionally graded beam (FGB) is investigated in this study on both dynamic and static loading in case of resting on a soil medium rather than on the usual Winkler-Pasternak elastic foundation. The powerful ABAQUS software was used to model the problem applying finite element method. In the present study, two different soil models are taken into account. In the first model, the soil is assumed to be an elastic plane stress medium. In the second soil model, the Drucker-Prager yield criterion, which is one of the most well-known elastic-perfectly plastic constitutive models, is used for modelling the soil medium. The results are shown to evaluate the effects of the different soil models, stiffness values of the elastic soil medium on the normal and shear stress and free vibration properties. A comparison was made to those from the existing literature. Numerical results show that considering real soil as a continuum space affects the results of the bending and the modal properties significantly.

Correlation of Experimental ana Analytical Inelastic Responses of 1:12 Scale Irregular High-Rise RC Buildings (1:12축소 비정형 고층 RC 건물의 비선형거동에 대한 실험과 해석의 상관성)

  • Ko, Dong-Woo;Lee, Han-Seon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.2 s.54
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    • pp.95-104
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    • 2007
  • Three types of high-rise RC building structures having irregularity in the lower two stories were selected as prototypes and were performed nonlinear static analysis by using OpenSees to verify the analysis technique and to investigate the seismic capacity of those buildings. The first one has a symmetrical moment resisting frame (Model 1), the second has an infilled shear wall in the central frame (Model 2), and the third has an infilled shear wall only in one of exterior frames (Model 3). Fiber model, which consists of concrete and reinforcing bar represented from stress-strain relationship, is adapted used for simulate the nonlinearity of members, and MVLEM(Multi vertical linear element model) is used for simulate the behavior of wall. The analytical results are simulate the behavior of piloti stories well, for example, the stiffness and yield farce of piloti stories, the up-lift of wall and the variation of lateral stiffness of column due to the variation of axial forces. Overstrength of Model 2 and Model 3 are about 2 times larger than that of Model 1. The reason of the high oversttrength and ductility of Model 2 and Model 3 is that the conservative design of Model 2 and Model 3, whose beam and column sections are the same as those of Model 1. The ductilities of Model 1 and Model 3 are slightly larger than that of Model 1 and Model 3. Model 1 and Model 3 reached mechanism condition, whereas Model 2 failed to the shear failure of shear wall and the large axial forces in columns due to large overturning moment.