• Elastomers and Composites
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• v.40 no.2
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• pp.104-111
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• 2005

Virgin fluororubber(FKM) that is one of the highly-functionalized and expensive special rubber, and recycled FKM that is crushed by high temperature shear-crushing technique from recycled FKM were blended with the various mixing ratio to rubber blends. The cure characteristics and physical properties of these blended rubber compounds were investigated with various contents of recycled FKM and physical properties fur heat and fuels were also measured. Recycled FKM which is prepared by high temperature shear-crushing technique were blended to virgin FKM with the range of $0{\sim}50$ phr. The physical properties indicated that the rubber blend of recycled FKM with 30 phr turned out to be the best compound showing good dispersibility, heat resistance and fuel resistance and inexpensive in price.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.820-828
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• 2003

Recent research has indicated that the current ACI shear provision provides unconservative predictions for large slender beams and beams with low level of longitudinal reinforcement, and conservative results for deep beams. To modify some problems of ACI shear provision, ultimate shear strength equation considering size effect and arch action to compute shear strength in high-strength concrete beams without stirrups is presented in this research. Three basic equations, namely size reduction factor, rho factor, and arch action factor, are derived from crack band model of fracture mechanics, analysis of previous some shear equations for longitudinal reinforcement ratio, and concrete strut described as linear prism in strut-tie model deep beams. Constants of basic equations are determined using statistical analysis of previous shear testing data. To verify proposed shear equation for each variable, effective depth, longitudinal reinforcement ratio, concrete compressive strength and shear span-to-depth ratio, about 300 experimental data are used and proposed shear equation is compared with ACI 318-99 code, CEB-FIP Model code, Kim &Park's equation and Zsutty's equation. The proposed shear equation is not only simpler than other shear equations, it is but also shown to be economical predictions and reasonable safety margin. Hence proposed shear strength equation is expected to be applied to practical shear design.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.1
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• pp.57-67
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• 1997

The objective of present paper is to investigate elasto-plastic behaviour and estimate the resistance capacity of a beam-shear wall structural system against earthquake ground accleration exciations. Pushover analysis is adopted to estimate inttiate and post stiffnesses and yielding point for inelastic response analysis in LPM (Lumped Parameter Mass) model, and modified Clough model is used as the hysteresis rule of each story. Three earthquake waves are used in the analysis but their peak ground accelerations are changed to be 0.12g, 0.24g. It is assumed that the earthquakes act in the longigtudianl direction of a 25 Story apartment building which consists of two some unit plan. The distribution of story ratio and ductility ratio are estimated and discussed within Korean, Japanese code and UBC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.4
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• pp.838-845
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• 2009

The inelastic response characteristics of the standard school buildings depending on selection of hysteresis models are reviewed. Three earthquake records of El-centre, Santa-Monica, Taft and three artificial earthquake records in accordance with Korea standard are used and the inelastic response characteristics such as story shear force, story drift ratio, story displacement, hinge distribution state are reviewed with various hysteresis models. As results, story shear force is increased by maximum 60% according to hysteresis model. And Story drift ratio is increased by maximum 42% according to hysteresis model. And The result with clough model shows the maximum hinge distribution state.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.21-29
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• 2014

This paper deals with the bonding characteristic of grouted joint connections of monopile support structures for offshore wind power facilities. For the integration of pile connection of wind power supporting structure, fiber reinforced high performance cementeous grout was developed and the ultimate compressive strength of it is 125MPa and the direct tensile strength is 7.5 MPa at 7 days. To assess the bond strength of grout filled in pile connection, small scaled direct bond tests under axially loaded was performed and analyzed according the existing guidelines. The fiber volume fraction (0%, 0.5% and 0.9%), aspect ratio of fiber (60 and 80) and the ratio of height to spacing of shear key (0.013 and 0.056) were adopted as the experimental variables. From the test results, the maximum bond strength among the all specimens was 30.8MPa and the bond strength of grouted connection was affected by the ratio of height to spacing of shear key than the fiber volume fraction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.647-653
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• 1997

To establish the index of aging stage for cold storage beef tenderloin, shear force value(SFV), Mg-ATPase activity, myofibrillar fragmentation index(MFI), myofibrillar fragmentation ratio(MFR) and appearance of 30KD(30KD) were measured as the parameters for the indices of aging stage. Aging index of air-packed beef tenderloin stored for 14 days at 3$^{\circ}C$ were useful in the order of SFV(r=-0.893)>MFR (r=0.863) >30KD(r=0.853)>MFI(r=0.814)>Mg-ATPase activity(г=0.804). Vacuum-packed beef tenderloin stored for 28 days at 3$^{\circ}C$ were useful in the order of MFR(r=0.880)>30KD(r=0.836). In case of the correlation between aging indices of air-packed beef tenderloin, MFR had relation with SFV, Mg-ATPase activity, MFI and 30KD. In case of the correlation between aging indices of vacuum-packed beef ten- derloin, MFR had relations with 30KD.

• Journal of the Korean Geotechnical Society
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• v.28 no.3
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• pp.45-54
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• 2012

Various geosynthetics are widely applied to civil structures and waste landfill site for reinforcement and water resistance. The use of geosynthetics inevitably involves the coupled behaviors of different materials which include large displacement and strain-softening behaviors, etc. In this study, the effect of chemical element in the leachate on the interface shear strength under the cyclic loading condition was analyzed. The Multi-purpose Interface Apparatus (M-PIA) has been modified and cyclic direct shear tests have been performed. The submerging period of each specimen is 200 days. Additionally, the Field-Emission Scanning Electronic Microscopy (FIB) analysis has been also performed to induce the reason of the variation of disturbance function and verify the hypothesis on the decay-proof ability of geosynthetics. Consequently, the charateristics of chemical degradation of geosynthetic-soil interface are verified and the variation of the disturbance function is mainly caused by the different type of soil mineral decay, based on the FIB results.

• Journal of the Korean GEO-environmental Society
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• v.14 no.2
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• pp.51-55
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• 2013

Among various construction methods, deep soil stabilization by chemical method have been widely used in order to improve soft ground. Dynamic variables using ground(such as sand, weathered granite soil and rock) -structure interaction design affected by dynamic load and cyclic load were studied a lot. However, there is something yet to learn about earthquake resistant design regarding reinforced ground by grout. Therefore, in this study using RC test, the correlation between shear strain and shear modulus with change of water content and injection rate in normal portland cement and clay was compared and analyzed by using Ramberg-Osgood model normalization As the result, dynamic coefficient was considerably affected by water content and grout injection rate.

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.505-517
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• 2004

This paper presented equations on the stress evaluation of steel frame pier connections that were composed of a box beam and a circular column. The existing equations, which transformed the circular column into an equivalent box column had some problems; they underestimated a shear lag stress as the joint angle decreased, and overestimated a shear stress as the joint angel increased. Therefore, FE analyses were performed with various parameters, such as joint angle(${\alpha}$), span length-width ratio(L/B), and circular column-to-box beam stiffness ratio(${\alpha}$), and new equations on stress evaluation were proposed based on FE analyses. Furthermore, material and geometric nonlinear analyses were performed to estimate ultimate strength and to confirm the validity of the proposed equations.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.1
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• pp.1-8
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• 2009

In order to evaluate the effect of shear wave velocity of a seismic control point on site response analysis, one-dimensional equivalent linear site response analysis were performed on the model soil profile based on the results of a detailed site investigation of sedimentary layers at Incheon and Busan. The results of the analysis show that an increase of shear wave velocity on the seismic control point (base rock) results in an increase of acceleration in the soil layers. This was mainly due to an unclear definition of the seismic control point. For this reason, the Korean Seismic Design Standard requires a specific definition of the seismic control point, including spatial conditions and soil properties, similar to the MCE (Maximum Considered Earthquake) in FEMA 369.