• Steel and Composite Structures
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• v.26 no.3
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• pp.347-360
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• 2018

The aim of this paper is to evaluate the accuracy and reliability of the available bond-slip laws which are being used for the numerical modeling of Fiber Reinforced Polymer (FRP)/concrete interfaces. For this purpose, a set of Reinforced Concrete (RC) beams retrofitted with external FRP were modeled using the 3D nonlinear Finite Element (FE) approach. All considered RC beams have been previously tested and the corresponding experimental data are available in the literature. The failure modes of these beams are concrete crushing, steel yielding and FRP debonding. Through comparison of the numerical and experimental results, the effectiveness of each FRP/concrete bond-slip model for the prediction of the structural behavior of externally retrofitted RC beams is assessed. The sensitivity of the numerical results against different modeling considerations of the concrete constitutive behavior and bond-slip laws has also been evaluated. The results show that the maximum allowable stress of FRP/concrete interface has an important role in the accurate prediction of the FRP debonding failure.

• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.303-306
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• 1994

Fundamental characteristics of giant magnetostrictive alloy $Terfenol-D(Tb_{0.3}Dy_{0.7}Fe_{1.9~1.95})$ are rreasured and discussed on the application for actuators. The magnetostriction is measured by laser displacement rreasuring system and the applied compressive stress is measured by load cell. Magnetostrictions increased as the applied compressive stresses increased. When the stress is 7 MPa, the magnetostriction is 1000 ppm at 1500 Oe. As the stresses iocreased from 0 to 14 MPa, the magnetic fields for saturating the magnetostriction also increased. The temperature increased during the experiment is $0.3^{\circ}C$, so the thermal expansion is negligible in these experirrents. The feedback or temperature control function should be added for the precise position control actuator.

• Journal of Wetlands Research
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• v.9 no.1
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• pp.1-11
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• 2007

The objectives of this study are: (1) to compare the rates and pathways of organic matter minerlaization at stagnant freshwater wetland in Shiwha to highly irrigated coastal wetland in Ganghwa; and (2) to discuss the significance of irrigation into the sediment in controlling the organic carbon oxidation in Shiwha wetland. Concentrations of $CO_2$, $NH_4{^+}$ and $H_2S$ in the pore water of the Shiwha wetland were 3 times, 30 times, and 3 times higher than that in the pore water of the Ganghwa wetland, respectively. The ratio of Fe(III) to total reduced sulfur at the Ganghwa wetland was 12 times higher than at the Shiwha wetland. The results indicated that the Ganghwa wetland with frequent tidal inundation were relatively oxidized than highly stagnant Shiwha wetland. Rates of organic matter oxidation at the Ganghwa wetland ($0.039mM\;C\;h{-1}$) was 390 times higher than that at the Shiwha wetland ($0.0001mM\;C\;h{-1}$). Rates of sulfate reduction at the Shiwha wetland ($314{\sim}580nmol\;cm^{-3}\;d{-1}$) were comparable to the sulfate reduction at Ganghwa wetland ($2{\sim}769nmol\;cm^{-3}\; d{-1}$), whereas Fe(III) reduction rates were 1.7 times higher at the Ganghwa wetland ($0.1368{\mu}mol\;cm^{-3}\;d{-1}$) than at the Shiwha wetland ($0.087{\mu}mol\;cm^{-3}\;d{-1}$). The results implied that the water flow system of the Shiwha wetland was too stagnant to flush out the reduced pore water from the sediment, and thus anaerobic microbial respiration was limited by the availability of electron acceptors.

• Korean Journal of Plant Resources
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• v.22 no.4
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• pp.349-358
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• 2009

The potential use of 4 plant species, Astragalus membranaceus var. membranaceus, Senna occidentalis, Dianthus longicalyx and Plantago asiatica, as new sprout vegetables with high antioxidant function was examined in the present experiments. Seeds of above plants were allowed to germinate under light condition, and seedlings were maintained under dark condition for shoot growth in length for contain period of time. Then the seedlings were put under light for photosynthesis (greening treatment) for the period of 0${\sim}$3 days. Samples were collected to analyze the changes in antioxidant levels and activity, and it was observed that antioxidant substances were affected by greening treatments, depending on plant species. In A. membranaceus, the contents of total polyphenol was highest with no greening, total flavonoids with 3 days greening, DPPH radical scavenging effects with no greening, ABTS scavenging with 1 day greening, $Fe^{2+}$ chelating effects with no greening, and inhibitory activity against linoleic acid peroxidation with 3 day greening. In S. occidentalis, highest levels of antioxidant activity and radical scavenging effects were obtained by 2 day greening, $Fe^{2+}$ chelating effects by no greening and inhibitory activity against linoleic acid peroxidation by 1 day greening. In D. longicalyx, highest levels of antioxidant activity and $Fe^{2+}$ chelating effects were obtained by 2 day greening, $Fe^{2+}$ chelating effects by no greening and inhibitory activity against linoleic acid peroxidation by 1 day greening. In D. longicalyx, highest levels antioxidant activity and $Fe^{2+}$ chelating effects were observed with 3 day greening, and highest radical scavenging effects and inhibitory activity against linoleic acid peroxidation with no greening treatment. In P. asiatica, antioxidant activity and radicals scavenging effects were highest with 2 day greening, whereas highest chelating effects was obtained with no greening and highset inhibitory activity against linoleic acid peroxidation with 3 day greening. As the length of greening treatments influenced the antioxidant levels and function in plant species tested in this experiments, different culture methods are recommended for different plant species to get maximum health benefits out of sprout vegetables.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.47-55
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• 2008

In this paper, comparisons are presented on the predicted tensile strains which can affect the fatigue life of a thin asphalt concrete (AC) pavement near the surface of pavement from three-dimensional (3D) finite element (FE) using 3D measured tire contact stresses of a radial tire and a bias ply tire and a layered linear elastic program (BISAR). The objective was to analyze the stress distributions for a 11R22.5 radial tire and a $10{\times}20$ bias ply tire, and to compare the predicted tensile strains at the top and bottom of AC surface using different analysis methods. The results show that the stress distributions of two tires are similar but the 11R22.5 radial tire has much higher vertical contact stress than that of the $10{\times}20$ bias ply tire. The predicted tensile strains at the bottom of AC layer under the center of tire showed higher value by BM (BISAR with the measured contact area) method, which the measured tire contact area is used in a layered elastic program, while the tensile strain at the top of AC surface of 3.5cm offset distance from tire edge by 3D FE analysis showed the highest values among three analysis methods.

• Journal of the Korean Magnetics Society
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• v.5 no.3
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• pp.203-209
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• 1995

A study of the dependence of the magnetoresistance in $glass\[Cu_{x\AA}\NiFe_{50\AA}\Cu_{x\AA}\Co_{50\AA}](X;\=\;8,\;10,\;14,\;18,\;22,\;26,\;28,\;38,\;48,\;58\;\AA,\;N\;=\;2,\;3,\;4,\;10,\;20)$ multilayers prepared by dc magnetron sputtering on the interlayer thickness of Cu (X), the number of multylayer(N) and annealing temperature has been performed. Resistance measurement were made by four terminal method, and the magnetic field applied to perpendicular and parallel for the current. The maximum magnetoresistance(MR) ratio(%) was appeared in the vicinity of $10\;\AA$ in Cu layer, and it was oscillated with the thickness of Cu. The MR ratio was increased with the number of layers N, however the ratio for the N = 4 layers decreased rather than the N = 3 layers. The dependence of the ratio on the annealing temperature was increased to $250^{\circ}C$.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.4
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• pp.98-108
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• 1998

Hull design data is currently prepared by a 2D CAD system and re-input to 3D CAD systems specialized for detail design or to a structural analysis system. In this paper, sharing design data among different CAD systems has been studied. Based on STEP methodology, a neutral model is generated from 2D AutoCAD drawings. To handle a geometric data of this model, the non-manifold model of ACIS is used because it can support various CAD data representation such as 2D graphic entities, 3D wireframe, 3D surface model, and solid B-Rep/CSG model. It is observed that a mon-manifold model can easily be transformed to a 3-D wireframe model for the hull detail design system AutoDef or a FE model for the structural analysis system Nastran.

• Journal of Soil and Groundwater Environment
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• v.16 no.1
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• pp.82-90
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• 2011

Reactive reductants of cement/Fe(II) systems in dechlorinating chlorinated hydrocarbons have not been identified. The previous studies showed that a hematite/CaO/Fe(II) system had TCE degradation characteristics similar to those of cement/Fe(II) systems with regard to degradation kinetics and that lime (CaO) plays an important role in enhancing the reactivity for TCE dechlorination. The current study shows identified the formation of gypsum ($CaSO_4$) in the hematite/CaO/$FeSO_4$ system through the XRD analysis. The amounts of the gypsum increased with increment of the initial CaO dose. However, when CaO in the hematite/CaO/$FeSO_4$ system was replaced with gypsum, TCE degradation was not observed. Ca-removed Portland cement extracts (CPCX) in combination with $FeSO_4(CPCX/FeSO_4)$ showed no TCE degradation. On the other hands, the Portland cement extracts (PCX) in the presence of $FeSO_4(PCX/FeSO_4)$ and CPCX/CaO/$FeSO_4$ systems degraded 0.2 mM TCE within 5 days, indicating that CaO also played an important role dechlorination reactions in the systems. The pseudo-first-order rate constants (k) of the CPCX/CaO/$FeSO_4$ systems were 0.20, 0.24, and 0.72 $day^{-1}$, when the CaO dosages were 25, 50 and 75 g/L, respectively. The XRD analyses showed identified the common peaks having the d-values of 3.02, 2.27, and 1.87 in the reaction systems that showed TCE degradation. However, it was not possible to clearly identify the crystalline minerals having the three peaks from the references in JCPDS cards. This study reveals that the reactive agents in the cement/Fe(II) and the hematite/Fe(II) systems are likely to be those containing CaO and Fe(II).

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.299-305
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• 2005

The work described in this paper is to investigate the additional iron losses and consequent temperatures in core ends of a turbo-generator wound with high voltage cables. Electromagnetic calculations are made with 3D FE models, which include the lamination material with anisotropic properties both in magnetic permeability and electric conductivity. The models also include the geometry of the stator teeth and eventually the axial steps designated to reduce the core end losses. The 3D model of the rotor consists of field windings with straight in-slot parts and end windings. The thermal models are simplified into two dimensions and include the heat sources dumped from the 3D electromagnetic solutions. The influences of power factor on additional iron losses are studied for this cable wound machine and conventional machines. The calculation results show that the additional iron losses can be reduced to about $15\%$ by introducing some small steps around the airgap corner of core ends.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.997-998
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• 2007

This paper deals with analytical solution concerning the image method using the magnetic charge instead of 3D FEA(finite element analysis) in the slotless single air-gap motor. The theory of analytical method and the design procedures are introduced. The reliability and validity of proposed analytical solution are verified through the comparison with the results of commercial 3D FE software. In addition, calculation time between proposed analytical solution and 3D FEA is compared. Finally, characteristics, such as Back-EMF and phase resistance, between calculated and experimental results are compared. From the verification with 3D FEA and experimental results, it is proved that presented analytical method provided very effective and precise results.