• Geomechanics and Engineering
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• v.8 no.3
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• pp.305-321
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• 2015

In this paper, a new hyperbolic shear deformation plate theory based on neutral surface position is developed for the static analysis of functionally graded plates (FGPs). The theory accounts for hyperbolic distribution of the transverse shear strains and satisfies the zero traction boundary conditions on the surfaces of the beam without using shear correction factors. The neutral surface position for a functionally graded plate which its material properties vary in the thickness direction is determined. The mechanical properties of the plate are assumed to vary continuously in the thickness direction by a simple power-law distribution in terms of the volume fractions of the constituents. Based on the present new hyperbolic shear deformation plate theory and the neutral surface concept, the governing equations of equilibrium are derived from the principle of virtual displacements. Numerical illustrations concern flexural behavior of FG plates with Metal-Ceramic composition. Parametric studies are performed for varying ceramic volume fraction, volume fraction profiles, aspect ratios and length to thickness ratios. The accuracy of the present solutions is verified by comparing the obtained results with the existing solutions.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.918-920
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• 2006

Metal sulfide powders such as MnS, $MoS_2$ and FeS are simply used to the machinery processing improvement agent and solid lubricant in powder metallurgy industrial. And then, metal sulfide powders have received relatively little attention from powder metallurgy. Recently, the portable machine is one of the important interfaces between human or human and electronic machine. With the increase of the intelligent activity, the social and industrial demands for information display device and power source are increasing. The transition metal sulfide materials (FeS, ZnS) have received considerable attention due to the large variety of its electric, optical and magnetic properties. Among the metal sulfide, $FeS_2$ is appealing superior material for applications in $Li-2^{nd}$ battery because of high capacity. ZnS is also a famous phosphor material with various luminescence properties, such as photoluminescence (PL) and electroluminescence (EL). So generally used in the fields of display, sensors and laser. Metal sulfide materials, therefore, are provided for most widely application in all industries. In recent years, material researchers have become increasingly interested in studying with synthesis of metal sulfide.

• Textile Coloration and Finishing
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• v.34 no.4
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• pp.250-260
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• 2022

In this research, a high-elasticity acrylic emulsion binder with core-shell polymerization and self-crosslinking system is mixed with a flame-retardant water-dispersed polyurethane (PUD) binder. In addition, finite element analysis was conducted through virtual engineering software ANSYS by applying three representative nonlinear material models. The most suitable nonlinear material model was selected after the relative comparison between the actual experimental values and the predicted values of the properties derived from simulations. The selected nonlinear material model is intended to be used as a nonlinear material model for computational simulation analysis that simulates the experimental environment of the vibration test (ASTM E1399) and the actual fire safety test (ASTM E1966). When the mass fraction of thermally expandable graphite was 0.7%, the thermal and physical properties were the best. Among the nonlinear material models, the simulation result of the Ogden model showed the closest value to the actual result.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2734-2741
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• 2023

Brachytherapy is a special case of radiotherapy. It should be arranged according to some principles in medical radiation applications and radiation physics. The primary principle is to use as low as reasonably achievable dose in all ionizing radiation applications for diagnostic and therapeutic treatments. Dosimetric distributions are dependent on radioactive source properties and radiation-matter interactions in an absorber medium such as phantom or tissue. In this consideration, the geometrical structure and material of the seed capsule, which surrounds a radioactive material, are directly responsible for isodose profiles and dosimetric functions. In this study, the radiometric properties of capsule material were investigated on dose distribution in a water phantom by changing its nuclear properties using the EGSnrc Monte Carlo (MC) simulation code. Effective atomic numbers of hypothetic mixtures were calculated by using different elements with several fractions for capsule material. Model 6711 brachytherapy seed was modeled by EGSnrc/Dosrcnrc Code and dosimetric functions were calculated. As a result, dosimetric parameters of hypothetic sources have been acquired in large-scale atomic number. Dosimetric deviations between the data of hypothetic seeds and the original one were analyzed. Unit dose (Gy/Particle) distributions belonging to different types of material in seed capsule have remarkably differed from the original capsule's data. Capsule type is major variable to manage the expected dose profile and isodose distribution around a seed. This study shows us systematically varied scale of material type (cross section or effective atomic number dependent) offers selective material usage in production of seed capsules for the expected isodose profile of a specific source.

• Journal of Magnetics
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• v.1 no.1
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• pp.19-23
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• 1996

In the present study, the $Sm_2Fe_{17}N_x$-type interstitial materials have been prepared by reaction between Nb-free or Nb-containing $Sm_2Fe_{17}$-type alloy and $N_2$ gas. Nitrogenation behaviour of the $Sm_2Fe_{17}N_x$-type material and disproportionation characteristics of the nitrogenated materials have been studied by means of differential thermal analysis (DTA) and thermopiezic analysis (TPA). Magnetic properties of the produced $Sm_2Fe_{17}N_x$-type interstitial materials were characterised in vibrating sample magnetometer (VSM) or thermomagnetic analyser (TMA). Epoxy-bonded or Zn-bonded $Sm_2Fe_{17}N_x$-type magnets were prepared, and their magnetic properties were investigated. It has been found that nitrogenation kinetics of the Sm2Fe17Nx-type alloy is improved significantly by the Nb-substitution for Fe in the alloy. The Nb-substitution is also found to enhance thermal stability of the $Sm_2Fe_{17}N_x$-type interstitial material. Hard magnetic properties of the interstitial materials produced from Nb-free orNb-containing alloy is high enough (intrinsic coercivity : over 7 kOe) for application as bonded permanent magnets. The good hard magnetic properties of the interstitial material are maintained in the epoxy-bonded magnet. Intrinsic coercivity of the Zn-bonded magnets is improved significantly as post-bonding annealing time increases.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.299-305
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• 2003

The battery industries have been developed to the implementation of lithium ion secondary cell from the cell of Ni/Cd and Ni/MH in the past to be asked of an age of high technology from low technology. Also in resent the polymeric cell to get a good high function with an age of new advanced information system is changed from the 21 century to the secondary batteries society. The properties of lithium secondary batteries have the high energy density, the long cycle time, the low self discharge area and the high active voltage. The wanted properties of secondary batteries for the motion of an apparatuses of industries of an high skill age have a small type trend of the energy density and it is become with a strong asking of the industrial society market about the storable medium of the convenience and new power energy. The electrochemical properties is researched for the cell to be synthesised and crystallized the positive active material LiMnO2 of the secondary cell at 9250C to get a new improved data of the electric discharge for that the capacitance of the LiMnO2 thin film that is improving and researching with the properties and a merit and demerit in the this kind of asking.

• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.440-447
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• 2011

To improving the mechanical properties of Mg alloys at high temperature, we investigated the mechanical properties at high temperature and the change of microstructure of Mg-6 wt%Zn-0.4 wt%Mn and Mg-6 wt%Zn-0.4 wt%Mn-1 wt%Ag alloys on age treatment that have a stable MgZn phase at high temperature and $AgMg_4$ improving yield stress. In order to predict thermodynamic data of Mg alloys, a phase diagram and precipitation phase were calculated using a thermodynamic program, and it was confirmed that the MgZn and $AgMg_4$ phase existed as main precipitation in this alloys. The experimental data examined using DSC and XRD were comparable with the calculated data for reliability. In order to analysis the microstructure and precipitate phase during aging treatment, it was measured by SEM/EDS and TEM. Lastly, mechanical properties of the MgZn and $AgMg_4$ phase were measured by a tensile test at high temperature.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3766-3777
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• 2022

It is essential to ensure the safety of spent nuclear fuel (SNF) transport cask in drop situation that is included in transport accident scenarios. The safety of the drop situation is affected by the impact absorption performance of impact limiters. Therefore, when designing an impact limiter, the uncertainty in the material properties that affect the impact absorption performance must be considered. In this study, the material properties of the wood inside the impact limiter were selected as the variables for a parametric study. The sensitivity analysis of the drop response of the SNF transport cask with impact limiter was performed. The minimum wood strength required to prevent a direct collision between the cask and floor was derived from the analysis results. In addition, the plastic strain response was analyzed and strain-based evaluation was performed. Based on this result, the critical values of wood properties that change the impact dynamic characteristics were investigated. Finally, the optimal material properties of wood were obtained to secure the structural safety of the SNF transport cask. The results of this study can contribute to the development of SNF transport cask, thereby ensuring safety in transport accident conditions.

• Korean Journal of Materials Research
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• v.32 no.6
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• pp.287-292
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• 2022

Magnesium-antimonide is a well-known zintl phase thermoelectric material with low band gap energy, earth-abundance and characteristic electron-crystal phonon-glass properties. The nominal composition Mg_3.8-xZn_xSb₂ (0.00 ≤ x ≤ 0.02) was synthesized by controlled melting and subsequent vacuum hot pressing method. To investigate phase development and surface morphology during the process, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were carried out. It should be noted that an additional 16 at. % Mg must be added to the system to compensate for Mg loss during the melting process. This study evaluated the thermoelectric properties of the material in terms of Seebeck coefficient, electrical conductivity and thermal conductivity from the low to high temperature regime. The results demonstrated that substituting Zn at Mg sites increased electrical conductivity without significantly affecting the Seebeck coefficient. The maximal dimensionless figure of merit achieved was 0.30 for x = 0.01 at 855 K which is 30% greater than the intrinsic value. Electronic flow properties were also evaluated and discussed to explain the carrier transport mechanism involved in the thermoelectric properties of this alloy system.

• Structural Engineering and Mechanics
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• v.82 no.1
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• pp.31-40
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• 2022

In structural engineering, the material properties of the structures such as elastic modulus, shear modulus, density, and size may not be deterministic and may vary at different locations. The dynamic response analysis of such structures may need to consider these properties as stochastic. This paper introduces a stochastic finite element method (SFEM) approach to analyze moving loads problems. Firstly, Karhunen-Loéve expansion (KLE) is applied for expressing the stochastic field of material properties. Then the mathematical expression of the random field is substituted into the finite element model to formulate the corresponding random matrix. Finally, the statistical moment of the dynamic response is calculated by the point estimation method (PEM). The accuracy and efficiency of the dynamic response obtained from the KLE-PEM are demonstrated by the example of a moving load passing through a simply supported Euler-Bernoulli beam, in which the material properties (including elastic modulus and density) are considered as random fields. The results from the KLE-PEM are compared with those from the Monte Carlo simulation. The results demonstrate that the proposed method of KLE-PEM has high accuracy and efficiency. By using the proposed SFEM, the random vertical deflection of a high-speed railway (HSR) bridge is analyzed by considering the random fields of material properties under the moving load of a train.