• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.142-148
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• 2013

Conventional cold isostatic pressing, slip casting, and filter pressing are not completely suitable for fabricating large plates because of disadvantages such as the high cost of equipment and formation of density gradient. These problems could be avoided by employing pressure-vacuum hybrid slip casting (PVHSC). In the PVHSC, the consolidation occurs not only by the compression of the slip in casting room, but also by vacuum sucking of the dispersion medium around the mold. We prepared the alumina bodies by the PVHSC in a static- or stepwise-pressure manner for loading up to 0.5 MPa using an aqueous slip. The green bodies were dried at $30^{\circ}C$ with 40 ~ 80% relative humidity. Under static pressure, casting induced a density gradient in the formed body, resulting in cracking and distortion after the firing. However, the stepwise pressure loading resulted in green bodies with homogeneous density, and the minimization of the appearance of those defects in final products. Desirable drying results were obtained from the cast bodies dried with 80% RH environment humidity. When sintered at $1650^{\circ}C$ for 4 h, the alumina plate made by stepwise-pressure casting reached full density (> 99.7% relative density).

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.127-134
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• 2015

Recently, the external bonding of carbon fiber reinforced polymer (CFRP) sheets has come to be regarded as a very effective method for strengthening of reinforced concrete structures. The behavior of CFRP-strengthened RC structure is mainly governed by the interfacial behavior, which represents the stress transfer and relative slip between concrete and the CFRP sheet. In this study, the effects of bonded length, width and concrete strength on the interfacial behavior are verified and a bond-slip model is proposed. The proposed bond-slip model has nonlinear ascending regions and exponential descending regions, facilitated by modifying the conventional bilinear bond-slip model. Finite element analysis results of interface element implemented with bond-slip model have shown good agreement with the experimental results performed in this study. It is found that the failure load and strain distribution predicted by finite element analysis with the proposed bond-slip are in good agreement with results of experiments.

• Economic and Environmental Geology
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• v.31 no.6
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• pp.547-555
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• 1998

A new trigonometrical method for calculating total slip (T) of faulting is presented. The parameters for the calculations are used rake of fault striation, strike and dip of fault and of index planar structure such as bedding plane. The faults are groupped into three types. The direction of plunging of fault striation is out of a range ${\pm}90^{\circ}$ to the bedding dip direction in $360^{\circ}$ system, which is groupped into the type I. Meanwhile, the case of the direction lies in the above range can be separated into two different types, type II and type III, according to relative largeness of the angles rake of fault striation and i (see text). The type II has smaller rake than angle i and the type III has larger rake than angle i. Here I propose a few equations for calculating not only total slip (T) but strike slip (L) or dip slip (S) of the faulting. The equations are adapted selectively to the types of fault mentioned before. The limitation of the method is that the equations do not fit to polyphase faulting.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.5
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• pp.56-61
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• 2007

In the braking of railway rolling stock, the slip that is the relative velocity between train body and its wheel affects the adhesive force which is connected to the braking force. The coefficient of the adhesive force changes in accordance with the slip and the condition of a rail road. Namely, its value increases upon the maximum on a rail condition, and there it declines conversely while the magnitude of slip keeps rising on. First, this paper introduced a reference slip generator so that can utilize maximum adhesive forces with a disturbance observer for estimating unmeasurable current adhesive forces which is as an input of the generator. And, an adaptive sliding-mode control system has been synthesized for minimizing the error between reference and current slip. Finally the effectiveness of the proposed control system is evaluated by computer simulation.

• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.1132-1141
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• 2019

Steel-concrete-steel (SCS) sandwich structures have important advantages over conventional concrete structures, however, bond-slip between the steel plate and concrete may lead to a loss of composite action, resulting in a reduction of stiffness and fatigue life of SCS sandwich structures. Due to the inaccessibility and invisibility of the interface, the interfacial performance monitoring and debonding detection using traditional measurement methods, such as relative displacement between the steel plate and core concrete, have proved challenging. In this work, two methods using piezoelectric transducers are proposed to detect the bond-slip between steel plate and core concrete during the test of the beam. The first one is acoustic emission (AE) method, which can detect the dynamic process of bond-slip. AE signals can be detected when initial micro cracks form and indicate the damage severity, types and locations. The second is electromechanical impedance (EMI) method, which can be used to evaluate the damage due to bond-slip through comparing with the reference data in static state, even if the bond-slip is invisible and suspends. In this work, the experiment is implemented to demonstrate the bond-slip monitoring using above methods. Experimental results and further analysis show the validity and unique advantage of the proposed methods.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.265-275
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• 2003

In this study, shaking table tests were conducted to estimate dynamic interface properties between geosynthetics such as geomembrane, geotextile and geosynthetic clay liner. Accelerations of both shaking table and upper box, and relative displacements between geosynthetics under dynamic loading were measured. Also, the influence of normal stress, frequency of excitation and dry/wet conditions were investigated through the analyses of test results. from the test results, it was found that there is a limited acceleration below which dynamic farce can be transmitted between geosynthetics without the loss of horizontal acceleration. Dynamic interface friction angle between geosynthetics could be calculated through the limited acceleration. Relative displacements induced along geosynthetic interfaces under dynamic loading were not consistent depending on the type of interface and test conditions. The maximum slip displacements between geosynthetics are normalized and normalized slip equations were developed for each interface. By using the normalized slip equation, maximum slip displacements for the geosynthetic interface could be predicted for the given base acceleration and frequency of excitation.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.917-922
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• 2002

This paper deals with the estimation of the maximum crack widths considering bond-slip relationships based on experimental data that were tensed by axial force. It is certificated that the concrete stress condition clearly affects the bond-slip relationship. The proposed method utilizes the conventional crack and bond-slip theories as well as the characteristics of deformed reinforcement and size effects. An analytical equation for the estimation of the maximum flexural crack width is formulated as a function of minimum crack length and the coefficient of bond stress effect. The validity, accuracy and efficiency of the proposed method are established by comparing the analytical results with the experimental data and the major specifications (e.g., ACI, CEB-FIP Model code, Turocode 2, JSCE, etc.). The analytical results presented in this paper indicate that the proposed method can be effectively estimated the maximum flexural crack width of reinforced concrete.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.866-867
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• 2006

This work will report a highly textured ${\beta}-Si_3N_4$ ceramic by aqueous slip casting in a magnetic field and subsequent pressureless sintering, Effects of the sintering aids, polymer dispersant, pH and stirring time on the stability of the $Si_3N_4$ slurries were studied. The textured ${\beta}-Si_3N_4$ with 97 % relative density could be obtained by slip casting in a magnetic field of 12 T and subsequent sintering at $1800^{\circ}C$ for 1 h. The textured microstructure is featured by the alignment of c-axis of ${\beta}-Si_3N_4$ crystals perpendicular to the magnetic field, and the Lotgering orientation factor, f, is determined to be 0.8.

• Composites Research
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• v.24 no.3
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• pp.17-24
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• 2011

The EAM simulation of nanoindentation was performed to investigate misfit dislocation slip in the Ag/Cu. The film layer, whose thickness in the range of 2-5nm, was indented by a spherical indenter with the N$\'{o}$se-Hoover thermostat condition. The simulation shows that the indentation position relative to misfit dislocation (MFD) has the effect on the dislocation, glide up or cross slip, for Ag film layer thickness less than 4 nm. Elastic energy variation during MFDs slip was revealed to be a key factor for the softening of Ag/Cu. The critical film layer thickness was evaluated for each case of Ag/Cu according to the spline extrapolation technique.

• Journal of Biomedical Engineering Research
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• v.21 no.3 s.61
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• pp.295-301
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• 2000

It is known that among many factors, relative micromotion at bone/implant interfaces can hinder bone ingrowth into surface pores of an implant. Loading conditions, mechanical properties of spinal materials, friction coefficients at the interfaces and geometry of spinal segments would affect the relative micromotion and spinal stability. A finite clement model of the human lumbar spine segments (L4-L5) was constructed to investigate the mechanical sensitivity at the interfaces between bone and cage. Relative micromotion. Posterior axial displacement. bone stress, cage stress and friction force were predicted in changes of friction coefficients, loading conditions. bone density and age-related material/geometric properties of the spinal segments. Relative micromotion (slip distance in a static loading means relative micromotion in routine activity) at the interfaces increased significantly as the mechanical properties of cancellous bone, annulus fibers or/and ligaments decrease or/and as the friction coefficient at the interfaces decreases. The contact normal force at the interfaces decreased as cancellous bone density decreases or/and as the friction coefficient increases A significant increase of slip distance at anterior annulus occurred with an addition of torsion to compressive preload. Relative micromotion decreased with an increase of disc area. In conclusion. relative micromotion, stress response. Posterior axial displacement and contact normal force are sensitive to the friction coefficient of the interfaces, bone density, loading conditions and age-related geometric/material changes.