• Composites Research
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• v.30 no.4
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• pp.247-253
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• 2017

In this study, the mechanical behavior and interface properties of boron nitride nanotube-poly(methyl methacrylate) nanocomposites are predicted using the molecular dynamics simulations and the double inclusion model. After modeling nanocomposite unit cell embedding single-walled nanotube and polymer, the stiffness matrix is determined from uniaxial tension and shear tests. Through the orientation average of the transversely isotropic stiffness matrix, the effective isotropic elastic constants of randomly dispersed microstructure of nanocomposites. Compared with the double inclusion model solution with a perfect interfacial condition, it is found that the interface between boron nitride nanotube and polymer matrix is weak in nature. To characterize the interphase surrounding the nanotube, the two step domain decomposition method incorporating a linear spring model at the interface is adopted. As a result, various combinations of the interfacial compliance and the interphase elastic constants are successfully determined from an inverse analysis.

• Transactions of Materials Processing
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• v.20 no.7
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• pp.504-511
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• 2011

The alkaline earth metal Ba has a relatively low melting point. Because of its significantly high affinity to oxygen, nitrogen and sulfur, it is highly functional as a steel refining agent. But Ba can adversely affect the properties of steel especially the workability, because it can form a variety of inclusions. So, understanding of these inclusions is needed for improvement of the properties of steel. Thus a fundamental study in the formation behavior of non-metallic inclusions in Ba added Hyper Duplex STS melts was investigated. The amount of Ba, holding time and temperature were considered as experimental variables. The number of non-metallic inclusions decreased and the large particle size of non-metallic inclusions increased as the amount of Ba increased. The number of non-metallic inclusions also decreased and the large particle size increased with increased holding times and temperatures of molten steel.

• Structural Engineering and Mechanics
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• v.44 no.6
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• pp.801-814
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• 2012

The strain rate effects on the interaction between a Mode I matrix crack and an inclined elliptic matrix-inclusion interface under dynamic tensile loadings were investigated numerically, and the results are in agreement with previous experimental data. It is found, for a given material system, that there are the first and the second critical strain rates, by which three kinds of the subsequent crack growth patterns can be classified in turn with the increasing strain rate, namely, the crack deflection, the double crack mode and the perpendicular crack penetration. Moreover, such a crack deflection/penetration behavior is found to be dependent on the relative interfacial strength, the inclined angle and the inclusion size. In addition, it is shown that the so-called strain rate effect on the dynamic strength of granule composites can be induced directly from the structural dynamic response of materials, not be entirely an intrinsic material property.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.366-372
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• 2002

Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface deject as like decarburization, surface roughness etc.. In this study, the surface conditions are measured to know tile influence on fatigue properties by two cases of shot peening of two-stage shot peening and single-stage shot peening. And for this study, three kinds of spring steel (JISG4081-SUP7,SAE 9254, DIN 50CrV4, ) are made. This study shows the outstanding improvement of fatigue properties at tire case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from (1) Decreasing the surface roughness (2) Unchanging the surface hardness (3) Increasing the compressive residual stress But, results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of high hardness.

• Coupled systems mechanics
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• v.8 no.3
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• pp.273-287
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• 2019

Elastoplastic analysis of an annular disc, being fully constrained on its outer rim and interacting with a purely elastic inclusion perfectly bonded with its inner rim, is conducted to study its plastic deformation and residual stress under thermal cycles. The system is termed the composite disc. Quasi-static plane-strain deformation is assumed, and the von Mises yield criterion with or without the Ludwik hardening rule is adopted in our finite element calculations. Effects of multiple material properties simultaneously being temperature dependent on the plastic behavior of the composite disc are considered. Residual stress is analyzed from a complete loading and unloading cycle. Results are discussed for various inclusion radii. It is found that when temperature dependent material properties are considered, the maximum residual stress may be greater than the maximum stress inside the disc at the temperature-loaded state due to lower temperature having larger yield stress. Temperature independent material properties overestimate stresses inside materials, as well as the elastic irreversible temperature and plastic collapse temperature.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.4
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• pp.18-29
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• 1998

This study was carried out to test the theory of planned behavior in recreational choices behavior. Lotte World was chosen as study area, and college students were selected by nonprobability sampling for two waves of data collection. The first wave of data were collected one weeks into the spring semester : intention, attitude, subjective norm, and perceived behavioral control were measured. To collect the data of the second wave, the same resondents were asked their behavior, one week data of the second wave, the same respondents were asked their behavior , one week prior to the final examination : whether they visited the Lotte World or not. Polychoric correlation among variables were calculated by the PRELIS because behavior was nominal variable. Then, weighted least square method was utilized to calibrate structural equation model by the LISREL version 7.2. Structural link effect on intention among three determinants : the direct effect on intention was 0.421 and the indirect effect via intention on behavior was 0.145, respectively. However, its effect on behavior was insignificant because actual control over 'visiting of Lotte World' was relatively high. A few comments were sugested on data collection, and inclusion of new variables was discussed for the sufficiency f the theory of planned behavior.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.834-840
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• 2008

We carried out fatigue testing with materials of aluminum alloyC7075-T6, 2024-T4) by rotary bending fatigue tester. We investigated fatigue limit, fatigue crack initiation, fatigue crack propagation behavior and possibility of fatigue life prediction to the different small circular hole defect. The summarized result are as follows; Fatigue limit of the smooth specimens were related tensile strength and yield strength. In case of more large applied stress and small circular hole crack defect, the fatigue crack was grown rapidly. The fatigue crack propagation behavior proceed at according to inclusion. Fatigue crack propagation ratio appeared instability and retardation phenomenon in the first half of fatigue life but appeared stability and replied in the latter half. On other hand, this experimental data of the materials are appeared fatigue life predictability.

• Journal of Distribution Science
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• v.22 no.5
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• pp.67-79
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• 2024

Purpose: The purpose of this study is to shopping medium determinants and consumer behavior differences based on the value of consumption. Methodology: The subjects of the survey were adult men and women in their 20s or older living in Korea, and 283 valid responses were obtained. A Logit model was used to identify consumption value factors and shopping medium choices. A t-test was conducted to analyze the differences between consumer behavior based on preferred shopping medium (on/offline). Results: The inclusion of community-oriented factors such as eco-friendliness and social contributions lead to higher likelihood of choosing offline shopping. In addition, consumers who value self-expression and who are price sensitive are more likely to choose online stores. Conclusions: It was found that community-oriented factors lead shoppers to choose offline shopping, and the need for self-expression lead shoppers to choose online stores.

• Transactions on Electrical and Electronic Materials
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• v.5 no.5
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• pp.173-179
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• 2004

The influence of heavily Si impurity doping in the GaN barrier of InGaN/GaN multi-quantum well structures of blue light emitting diodes were investigated by growing samples in metal-organic chemical vapor deposition. The delta-doped sample was compared to the sample with the undoped barrier. The delta-doped sample shows the tunneling behavior and forms the energy level of 0.32 eV for tunneling and the photoemission of the 450-nm band. The photo-luminescence shows the blue-shifted broad band of the radiative transition due to the inclusion of Si delta-doped layer indicating that the delta doping effect acts to form the higher energy level than that of quantum well. The dislocation may provide the carrier tunneling channel and plays as a source of acceptor. During the tunneling of hot carrier, there was no light emission.

• Environmental Analysis Health and Toxicology
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• v.12 no.3_4
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• pp.75-84
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• 1997

Chromatographic retention behavior and separation of various phenol derivatives on a Partisil 10 ODS 3 column-with mobile phase containing $\alpha$-cyclodextrin-were systematically studied. The decrease in k' values caused by the addition of cyclodextrins in the mobile phase was based on the formation of an inclusion complex, resulting in weakening of the hydrophobic interaction between solutes and the stationary phase. The content of the organic solvent in the mobile phase also influenced k' values of the solutes, and k' values increased with a decrease of the content of organic solvent in the mobile phase. A simple equation has been derived that reveals the hyperbolic dependence of the capacity factor on the total concentration of cyclodextrin. A plot of the reciprocal of the capacity factor against (CD)$_T$ gives a straight line and the dissociation constant, K$_D$, of the inclusion complex can be calculated from the slope. The capacity factor decreased with increasing temperature. The enthalpy was calculated from the slope of van't Hoff plots. Under optimum conditions, some mixtures of phenol derivatives were able to separated successfully.