• Composites Research
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• v.28 no.6
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• pp.356-360
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• 2015

In this paper, the carbon fiber reinforced plastic is processed as the double cantilever beam in order to estimate the fracture behavior of composite and is carried out with the static analysis as the mode I. The specimen sizes are 25 mm, 30 mm, 35 mm and 40 mm. And the material property is used with carbon. As the analysis result of mode I, the adhesive part is detached latest by the small force at the specimen thickness of 25 mm. The largest force is happened at the specimen thickness of 40 mm. The defection of the adhesive interface is shown slowest at the displacement of 9.75 mm at the specimen thickness of 25 mm. And the defection is shown quickest at the displacement of 7.82 mm at the specimen thickness of 40 mm. This defection is due to the fracture of specimen. The result of this study on the defection of the adhesive interface and the reaction force due to this defection is thought to be contributed to the safe structural design of the carbon fiber reinforced plastic.

• Structural Engineering and Mechanics
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• v.73 no.3
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• pp.353-365
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• 2020

In the previous studies, the authors proposed the use of laminated veneer lumber - carbon fiber reinforced polymer (LVL-CFRP) composite beams for structural application. Bond strength of the LVL-to-CFRP interface and flexural strengthening schemes to increase the bending capacity subjected to positive and negative moment were discussed in the previous works. In this article, theoretical models are proposed to predict the moment capacity when the LVL-CFRP beams are subjected to negative moment. Two common failure modes - CFRP fracture and debonding of CFRP are considered. The non-linear model proposed for positive moment is modified for negative moment to determine the section moment capacity. For the debonding based failure, previously developed bond strength model for CFRP-to-LVL interface is implemented. The theoretical models are validated against the experimental results and then use to determine the moment-rotation behaviour and rotational rigidity to compare the efficacy of various strengthening techniques. It is found that combined use of bi- and uni-directional CFRP U-wrap at the joint performs well in terms of both moment capacity and rotational rigidity.

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.815-822
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• 1994

Sessile drop studies of molten Al on single crystal sapphire substrate were conducted to understand the wetting behavior and interfacial reaction at Al/Al2O3 interface. To investigate the wetting mechanism, the variation in contact angle was determined with time. The contact angle obtained in this study decreased exponentially with time. This result means that the driving force for wetting is the reduction in interfacial energy between liquid Al and sapphire caused by the interfacial reaction. The closer examination revealed that the reaction was the dissolution of sapphire by molten Al. Ti has been frequently used to improve wetting on ceramic materials. Therefore, the influence of Ti content on the wetting behaviour was investigated in this work. The equilibrium wetting angles of pure Al, Al-0.3 wt%Ti, and Al-1.0 wt%Ti at 100$0^{\circ}C$ were 63$^{\circ}$, 59$^{\circ}$, and 54$^{\circ}$respectively. The difference is considered as the result of the change in interfacial energy caused by the reaction between Ti and sapphire and the interfacial reaction formed the reaction products of varying stoichiometry (TiO, Ti2O3, TiO2 etc.).

• Carbon letters
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• v.3 no.4
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• pp.192-197
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• 2002

Microstructure plays an important role in controlling the fracture behaviour of carbon-carbon composites and hence their mechanical properties. In the present study effort was made to understand how the different interfaces (fiber/matrix interactions) influence the development of microstructure of the matrix as well as that of carbon fibers as the heat treatment temperature of the carbon-carbon composites is raised. Three different grades of PAN based carbon fibres were selected to offer different surface characteristics. It is observed that in case of high-strength carbon fiber based carbon-carbon composites, not only the matrix microstructure is different but the texture of carbon fiber changes from isotropic to anisotropic after HTT to $2600^{\circ}C$. However, in case of intermediate and high modulus carbon fiber based carbon-carbon composites, the carbon fiber texture remains nearly isotropic at $2600^{\circ}C$ because of relatively weak fiber-matrix interactions.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.1-8
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• 2013

Recently, the automotive technology has developed with electronics and information technology as convergence technology while vehicles had been regarded as machines. Moreover, vehicles are becoming more intelligent and safer devices, assembly of advanced technologies by customers' demand. Even though all of installations of vehicle have attracted as diverting devices, it cause drivers' mistakes like delay of response on traffic condition. Here, we proposed the Field Operational Test (FOT) environment which could be used as driving and road conditions collector(Vehicle motion, Traffic condition, Driver input, Driver state, etc.) for researches about Driver Friendly Intelligent System(SCC, LDWS, etc.), Human Vehicle Interface(Driving Workload, etc.) and Economic Drive Model. Furthermore driving patten and fuel consumption patten of drivers were analyzed by measured data and direction of future research was suggested.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1061-1064
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• 2008

Shear connectors have a finite slip capacity because of the mechanism by which they transfer the shear between UHPFRC and NC elements. At high degree of shear connection, non-linear analysis techniques are required to allow for compressive plasticity and tensile cracking behaviour of the elements. As with all non-linear problems, a closed form solution is difficult to find. A Modified Shooting Method Technique is developed here for non-linear analysis of UHPFRC/concrete composite. The initial effective moment is derived according to the prestressing force. The composite structure is divided into small segments which length is much less than the length of the structure and it can be assumed that the forces and displacements within each segment are constant. An equivalent analysis in composite girders would be to fix the slip strain in each segment and develop a moment curvature relationship for this slip strain in each segment. Additive forces and moment analysis on each section of the segments are analyzed by MSMT. Finally the ultimate slippage of the interface can be evaluated by the MSMT model. This paper presents a nonlinear analysis method for limited slip capacity of UHPFRC-NC interface.

• Journal of Biosystems Engineering
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• v.26 no.5
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• pp.481-486
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• 2001

To increase the production efficiency in dairy industry, proper artificial insemination is the most important operation. For the successful artificial insemination, accurate estrus detection is required. The Korean dairy farmers usually depended on visual observation for estrus detection of cows. Mounting behaviour is one of major inidications observed when cows are at an estrus. A mounting activity detection system for cows using radiotelemetry was developed. This system included a transmitter with a pressure switch, a receiver, a serial communication interface, a personal computer and a computer software. All components and a whole system were tested both in a laboratory and in a farm. The results of this study are as follows: 1. All components including transmitter, receiver and serial interface were operated according to the design specification. 2. A whole system tested with simulated mounting activity of 400 times showed 100% of success rate. 3. In the farm test for 4 days with three cows expecting estrus, one cows experiencing mounting activities showed correct response with this system. However two cows did not show mounting activities because of weak estrus and cold weather during the testing period.

• Structural Engineering and Mechanics
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• v.72 no.3
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• pp.293-304
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• 2019

In this paper, a general model is developed to predict the distribution of interfacial shear and normal stresses of FG beam reinforced by porous FGM plates under mechanical loading. The beam is assumed to be isotropic with a constant Poisson's ratio and power law elastic modulus through the beam thickness. Stress distributions, depending on an inhomogeneity constant, were calculated and presented in graphicals forms. It is shown that both the normal and shear stresses at the interface are influenced by the material and geometry parameters of the composite beam, and it is shown that the inhomogeneities play an important role in the distribution of interfacial stresses. The results presented in the paper can serve as a benchmark for future analyses of functionally graded beams strengthened by imperfect varying properties plates. Numerical comparisons between the existing solutions and the present new solution enable a clear appreciation of the effects of various parameters. The results of this study indicated that the imperfect functionally graded panel strengthening systems are effective in enhancing flexural behavior of the strengthened FGM beams. This research is helpful in understanding the mechanical behaviour of the interface and design of hybrid structures.

• Advances in materials Research
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• v.11 no.3
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• pp.171-190
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• 2022

In this paper, the problem of interfacial stresses in steel cantilever beams strengthened with bonded composite laminates is analyzed using linear elastic theory. The analysis is based on the deformation compatibility approach, where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. The original study in this paper carried out an analytical solution to estimate shear and peel-off stresses, as, interfacial stress analysis concentration under the uniformly distributed load and shear lag deformation. The theoretical prediction is compared with authors solutions from numerous researches. This phenomenon of deformation of the members, which gives probably approach on the study of interface of the reinforced structures, is called "shear lag effect". The resolution in this paper shows that the shear stress and the normal stress are significant and, are concentrated at the end of the composite plate of reinforcement, called "edge effect". A parametric study is carried out to show the effects of the variables of design and the physical properties of materials. This research is helpful for the understanding on mechanical behaviour of the interface and design of such structures.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.2
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• pp.74-84
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• 2016

After installing roundabouts, changes of travel behaviour in the vicinity of roundabouts can cause increasing traffic volumes and unbalanced flow conditions. In that cases, the efficiency of roundabouts as a whole intersections can drop due to the insufficient gap between vehicles in the circulating lanes. The purpose of this study is developing a dynamic signal metering operation method for roundabouts in which a real time Signal Metering operation algorithm is suggested and its performance is tested by using VISSIM COM Interface(Visual Basic Application). The results of the real time Signal Metering operation show that there is a substantial delay improvements when two adjoined approaches are combined together and the flows of metering approach are less than controlling approach. Especially, the total entering flow is around 1,600 vehicle/h gives the delay reduction per vehicle of 70.9~102.2(73.8~77.8%) seconds for four-lane-approach with one-lane roundabouts.