• Progress in Superconductivity and Cryogenics
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• v.21 no.2
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• pp.1-9
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• 2019

Practical superconducting wires are designed with a composite structure to meet the desired engineering characteristics by expert selection of materials and design of the architecture. In practice, the local strain exerted on the superconducting component influences the electromagnetic properties. Here, recent progress in methods used to measure the local strain in practical superconducting wires and conductors using quantum beam techniques is introduced. Recent topics on the strain dependence of critical current are reviewed for three major practical wires: $Nb_3Sn$, BSCCO-2223 and REBCO tapes.

• Coupled systems mechanics
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• v.10 no.2
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• pp.143-159
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• 2021

The theory of generalized thermo-magneto-electroelasticity is employed to obtain the plane wave solutions in an unbounded, homogeneous and transversely isotropic medium. Reflection phenomena of plane waves is considered at a stress free and thermally insulated surface. For incidence of a plane wave, the expressions of reflection coefficients and energy ratios for reflected waves are derived. To explore the characteristics of reflection coefficients and energy ratios, a quantitative example is set up. The half-space of the thermo-magneto-electroelastic medium is assumed to be made out of lithium niobate. The dependence of reflection coefficients and energy ratios on the angle of incidence is illustrated graphically for different values of electric, magnetic and thermal parameters.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.27-50
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• 2009

This paper describes an adaptive management approach for predicting, monitoring, and controlling ground movements associated with excavations in urban areas. Successful use of monitoring data to update performance predictions of supported excavations depends equally on reasonable numerical simulations of performance, the type of monitoring data used as observations, and the optimization techniques used to minimize the difference between predictions and observed performance. This paper summarizes each of these factors and emphasizes their inter-dependence. Numerical considerations are described, including the initial stress and boundary conditions, the importance of reasonable representation of the construction process, and factors affecting the selection of the constitutive model. Monitoring data that can be used in conjunction with current numerical capabilities are discussed, including laser scanning and webcams for developing an accurate record of construction activities, and automated and remote instrumentations to measure movements. Self-updating numerical models that have been successfully used to compute anticipated ground movements, update predictions of field observations and to learn from field observations are summarized. Applications of these techniques from case studies are presented to illustrate the capabilities of this approach.

• Advances in aircraft and spacecraft science
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• v.11 no.1
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• pp.1-21
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• 2024

The stiffness reduction of cross-ply composite laminates featuring a transverse cracking and delamination within the mid-layer is predicted through utilization of a modified shear-lag model, incorporating a stress perturbation function. Good agreement is obtained by comparing the prediction models and experimental data. The material characteristics of the composite are affected by fluctuations in temperature and transient moisture concentration distribution in desorption case, based on a micro-mechanical model of laminates. The transient and non-uniform moisture concentration distribution induces a stiffness reduction. The obtained results demonstrate the stiffness degradation dependence on factors such as cracks density, thickness ratio and environmental conditions. The present study underscores the significance of comprehending the degradation of material properties in the failure progression of laminates, particularly in instances of extensive delamination growth.

• Journal of Agricultural Extension & Community Development
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• v.31 no.2
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• pp.67-83
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• 2024

This study aims to explore a biological interpretation of farming practices mentioned in 'Sallimgyeongje(山林經濟)', an agricultural literature published in late 18C, in order to substantiate its scientific practicality and suggest the sustainable direction of modern agriculture. First, the research revealed that weeds and pests were effectively controlled by interspecies interactions such as allelopathy, mutualism, and interplanting. Second, qualified seeds were selected without dependence on chemical treatments by using specific gravity and cold water immersion. Third, the literature proposed plowing methods based on the properties of the soil, which implicated an establishment of healthy landscape mosaic by imitating the succession and introducing the moderate disturbance. Fourth, the genotypes of 37 native rice varieties were speculated based on six phenotype standards, and some of them are expected to have high nutritional value and abiotic stress resistance.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.977-981
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• 1998

Controlling the wafer temperatures from 200 to$500^{\circ}C$, low resistive tungsten thin films used for VLSI metallization are deposited by PECVD method. Resistivities of plasma deposited tungsten thin films are very sensitive to the $H_2/WF_6 $ partial pressure ratios. Residual stress behaviors of the films as a function of plasma power density were also studied. At the power density under the $0.7W/\textrm{cm}^2$, residual stress of W film is about $2.4\times10^9dyne/\textrm{cm}^2$. When the power density is. however, increased from 1.8 to $2.7W/\textrm{cm}^2$, residual stress is suddenly increased from $8.1\times10^9$ to $1.24\times10^{10}dyne/\textrm{cm}^2$ ue to the ion or radical bombardment at high power density.

• Korean Journal of Materials Research
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• v.11 no.2
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• pp.82-87
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• 2001

The hot deformation behavior of Ti-6Al-2Sn-4Zr-6Mo(Ti6246) alloy was investigated in both the $\alpha$+$\beta$ and $\beta$-phase fields by conducting compression tests over a strain rate range of $10^{-3}s^{-1}$ to $10^0s^{-1}$. The flow stress was increased with increasing strain rate and decreasing test temperature. The flow curves obtained at temperatures below 90$0^{\circ}C$ exhibited a flow softening. However, in the $\beta$-phase field, above 95$0^{\circ}C$, the flow stress increased monotonically with plastic strain approaching steady state values. Constitutive equations for the dependence of flow stress on strain, strain rate, and temperature were developed through the analysis of the flow curves.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.2
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• pp.191-197
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• 1987

It has been well known that the fracture mechanics can be applied to large through crack growth. But the growth rate of small surface cracks initiated from a small defect under rotary bending fatigue tests can not be treated as a function of stress intensity factor range. In this paper, to investigate the growth behavior of surface small fatigue cracks in the view-point of both fracture mechanics and strength of materials, the fatigue test has been carried out on two kinds of plain carbon steels with a small surface defect. Applying the concept of the cyclic strain intensity factor range .DELTA. $K_{\epsilon}$/$_{t}$ to the analysis of small surface fatigue crack growth, it is found that the relationship between cyclic strain intensity factor range and crack growth rate shows linear relation on logarithmic coordinates regardless of defect sizes and two kinds of carbon steels.s.s.

• Journal of Convergence for Information Technology
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• v.9 no.9
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• pp.237-244
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• 2019

This study aimed to investigate the effects of motive of use, stress and interpersonal satisfaction on smartphone overdependence in dental hygiene undergraduates. A questionnaire survey was conducted on 216 dental hygiene students in colleges in Dajeon and Chungnam regions. The results showed that motive of use(3-4hours/>4hours)(${\beta}=-0.178$), weekday usage (<3hours/3-4hours)(${\beta}=0.163$), and weekday usage (${\beta}=0.196$) had a high impact on smartphone overdependence in dental hygiene students. Weekday usage dummy 1 was the factor with the greatest impact, with an explanatory power of 25.6%. Additional studies on various factors that affect smartphone overdependence as well as education programs for preventing smartphone overdependence in dental hygiene students are needed.

• Journal of the Korean Geotechnical Society
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• v.26 no.6
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• pp.21-28
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• 2010

Decomposed granite soil is the most common type of soils. The measurement of the stress-strain-strength behavior of anisotropic decomposed granite soils is very important for the deformation and stability analysis of slopes, retaining walls, excavations. A series of unsaturated-drained triaxial compression tests were performed to know unsaturated strength properties. The sample had three different angles of the axial (major principal) direction to the sedimentation plane (compaction plane): 0, 45 and 90 degrees. The compression strain of specimens subjected to an isotropic compression was strongly influenced by the sedimentation angle. In addition, the time dependence was independent of the sedimentation angle in relation to the deformation behavior during the secondary compression process. The effect of the sedimentation angle on the triaxial compression strength and deformation was clearly shown with low confining stress. The effect of the sedimentation angle on the compressive strength and deformation was more evident in saturated specimens. A new method of predicting the shear strength of unsaturated decomposed granite soils, considering compaction angles, was proposed.