• 한국안전학회지
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• 제20권2호
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• pp.84-90
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• 2005

This study is to use results of the experiment on the influence to the strength by mixing powders of wasted tires into regular remicon within a range of little effectiveness in durability, applicability, economic aspect, and workability, to put it to practical use and to apply as basic data from a view of recycling wasted tires as construction materials. And the concrete, which was mixed with 10mm particles with ratio of $0.5\%\;and\;1.0\%$ respectively at 270 of mixing strength, was reduced by $27\%$ in compressive strength compared to normal concrete, whereas concrete mixed with other than 10mm particles showed lower decrease ratio compared to the former by reducing only $1.0\%\~1.5\%$. it is found that as strength increases, the less in quantity of aggregate and the more increase in quantity of cement. When considered to the above result, it is estimated that concrete mixed with wasted tire particles could be better used in conditions of compressive force rather than tensile force, and could also be used for structures with flexural strengths as well. In conclusion, higher strengths could be made using waste tire mix.

• Steel and Composite Structures
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• 제22권2호
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• pp.217-234
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• 2016

In order to investigate mechanical properties and load-bearing capacity of T-shaped Concrete-Filled Square Steel Tubular (TCFST) composite columns under eccentric axial load, three T-shaped composite columns were tested under eccentric compression. Experimental results show that failure mode of the columns under eccentric compression was bending buckling of the whole specimen, and mono column performs flexural buckling. Specimens behaved good ductility and load-bearing capacity. Nonlinear finite element analysis was also employed in this investigation. The failure mode, the load-displacement curve and the ultimate bearing capacity of the finite element analysis are in good agreement with the experimental ones. Based on eccentric compression test and parametric finite element analysis, the calculation formula for the equivalent slenderness ratio was proposed and the bearing capacity of TCFST composite columns under eccentric compression was calculated. Results of theoretical calculation, parametric finite element analysis and eccentric compression experiment accord well with each other, which indicates that the theoretical calculation method of the bearing capacity is advisable.

• 한국응용과학기술학회지
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• 제22권2호
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• pp.116-122
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• 2005

Room temperature cure type of acryl-urethane coatings with high solid content were prepared in this study. Acrylic resins with 80% solid content were cured with hexamethylene diisocyanate (Desmodure N-3600). The cure time of prepared coatings BEHCC-84 (BEHC-84 : $T_g=0^{\circ}C$) and BEHCC-87 (BEHC-87 : $T_g=30^{\circ}C$), measured by rigid-body pendulum method, was recorded 8.3 hours and 3.8 hours, respectively. Dynamic viscoelastic experiment also revealed the glass transition temperature of BEHCC-84 and BEHCC-87 to be $T_g=40.3^{\circ}C$ and $T_g=43.3^{\circ}C$, respectively. It was found that the adhesion and flexural properties among various propeties of coatings were enhanced by the incorporation of caprolactone acrylate monomer into the acrylic resins.

• KCI Concrete Journal
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• 제14권4호
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• pp.171-177
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• 2002

Antifungal agents are used to impart antibacterial or bactericidal properties to commodities and various articles used in industries and can be classified into two broad groups i.e organic and inorganic. Inorganic antifungal agents comprise of Ag, Zn, or Cu, etc. These elements tend to exhibit high level of antifungal activities, non-uniform dispersion in substrates, and have poor properties in expensive and cheap adhesiveness. In this study, the organic antifungal agent was used for the purpose of investigating the antifungal activity of antifungal agent activated-cement mortar (AACM) on the aspergilus niger of various fungus which can be easily discovered in the interiors and exteriors of buildings. In addition, an experiment on the basic physical properties of AACM such as compressive and flexural strength was carried out. The conclusion of this investigation revealed that a dosage increase of antifungal agent exhibits a high inhibitory effect on the aspergilus niger, and although there is a slight decrease in the strength of AACM, the strength of AACM was almost equal to that of inactivated cement mortar.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.192-192
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• 2008

This paper represents a piezoelectric ultrasonic linear motor by traveling wave. The motor which is composed of two piezo ceramics, elastic body, and connecting tip is driven by the frictional force between the connecting tip and the linear motion guide. longitudinal and flexural vibrations are made by traveling wave which is generated when the ultrasonic electrical signals with 90 degree phase difference are applied to two ceramics. These vibrations contribute to elliptical motion by mixed mode between longitudinal and transverse mode. A linear movement can be easily obtained by using the elliptical motion. In this paper, the piezoelectric actuator has been intensively simulated by using ATILA to achieve an optimized elliptical motion of it. We could get the elliptical motion from actual experiment through the simulated result.

• 한국지능시스템학회논문지
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• 제8권2호
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• pp.50-59
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• 1998

This paper presents stabilization and adaptive control of flexible single link robot manipulator system by self-recurrent neural networks that is one of the neural networks and is effective in nonlinear control. The architecture of neural networks is a modified model of self-recurrent structure which has a hidden layer. The self-recurrent neural networks can be used to approximate any continuous function to any desired degree of accuracy and the weights are updated by feedback-error learning algorithm. When a flexible manipulator is rotated by a motor through the fixed end, transverse vibration may occur. The motor toroque should be controlled in such a way that the motor rotates by a specified angle, while simultaneously stabilizing vibration of the flexible manipuators so that it is arresed as soon as possible at the end of rotation. Accurate vibration control of lightweight manipulator during the large changes in configuration common to robotic tasks requires dynamic models that describe both the rigid body motions, as well as the flexural vibrations. Therefore, a dynamic models for a flexible single link robot manipulator is derived, and then a comparative analysis was made with linear controller through an simulation and experiment. The results are proesented to illustrate thd advantages and imporved performance of the proposed adaptive control ove the conventional linear controller.

• 한국지진공학회논문집
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• 제17권3호
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• pp.97-105
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• 2013

In this paper, the a static experiment of on two reinforced concrete (RC) frame sub-assemblages was conducted to evaluate the seismic behaviors of existing RC frames that were not designed to support a seismic load. The specimens were a one span and actual-sized. One of them had two columns with the same stiffness, but the other had two columns with different stiffness values. As Regarding the test results, lots of many cracks occurred on the surfaces of the columns and beam-column joints for the two specimens, but the cover concrete splitting hardly occurred was minimal until the test ends. In the case of the specimen with the same stiffness offor the two columns, the flexural collapse of the left-side column occurred. However, in the case of the specimen with different stiffness values for of the two columns, the beam-column joint finally collapsed, even though the shear strength of the joint was designed to be strong enough to support the lateral collapse load. The nonlinear Nonlinear static analysis of the two specimens was also conducted using the uniaxial spring model, and the analytical results successfully simulated the nonlinear behaviour of the specimens in accordance with the test results.

• 한국소음진동공학회논문집
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• 제19권9호
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• pp.935-942
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• 2009

In this paper, the purpose is to investigate the natural frequency of a cracked Timoshenko cantilever beams by FEM(finite element method) and experiment. In addition, a method for detection of crack in a cantilever beams is presented based on natural frequency measurements. The governing differential equations of a Timoshenko beam are derived via Hamilton's principle. The two coupled governing differential equations are reduced to one fourth order ordinary differential equation in terms of the flexural displacement. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. The detection method of a crack location in a beam based on the frequency measurements is extended here to Timoshenko beams, taking the effects of both the shear deformation and the rotational inertia into account. The differences between the actual and predicted crack positions and sizes are less than 6 % and 23 % respectively.

• Structural Engineering and Mechanics
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• 제30권2호
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• pp.211-223
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• 2008

A number of studies have suggested that the use of high ductile and high shear materials, such as Engineered Cementitious Composites (ECC) and High Performance Fiber Reinforced Cementitious Composites (HPFRCC), significantly enhances the shear capacity of structural elements, even with/without shear reinforcements. The present study emphasizes the development of a nonlinear model of shear behaviour of a HPFRCC panel for application to the seismic retrofit of reinforced concrete buildings. To model the shear behaviour of HPFRCC panels, the original Modified Compression Field Theory (MCFT) for conventional reinforced concrete panels has been newly revised for reinforced HPFRCC panels, and is referred to here as the HPFRCC-MCFT model. A series of experiments was conducted to assess the shear behaviour of HPFRCC panels subjected to pure shear, and the proposed shear model has been verified through an experiment involving panel elements under pure shear. The proposed shear model of a HPFRCC panel has been applied to the prediction of seismic retrofitted reinforced concrete buildings with in-filled HPFRCC panels. In retrofitted structures, the in-filled HPFRCC element is regarded as a shear spring element of a low-rise shear wall ignoring the flexural response, and reinforced concrete elements for beam or beam-column member are modelled by a finite plastic hinge zone model. An experimental study of reinforced concrete frames with in-filled HPFRCC panels was also carried out and the analysis model was verified with correlation studies of experimental results.

• Structural Engineering and Mechanics
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• 제30권2호
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• pp.247-261
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• 2008

Performance of shear-deficient reinforced concrete (RC) beams strengthened with carbon fiber-reinforced polymer (CFRP) strips/sheets is analyzed through numerical simulations on four-point bending tests. The numerical simulations are carried out using the finite element (FE) program ABAQUS. A micromechanics-based constitutive model (Liang et al. 2006) is implemented into the FE program ABAQUS to model CFRP strips/sheets. The predicted results are compared with experiment data (Khalifa and Nanni 2002) to assess the accuracy of the proposed FE analysis approach. A series of numerical tests are conducted to investigate the influence of stirrup lay-ups on the shear strengthening performance of the CFRP strips/sheets, to illustrate the influence of the damage parameters on the microcrack density evolution in concrete, and to investigate the shear and flexural strengthening performance of CFRP strips/ sheets. It has been shown that the proposed FE analysis approach is suitable for the performance prediction of RC beams strengthened with CFRP strips/sheets.