• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.501-503
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• 1998

In this work, we applied the 1D $11^B$ nutation NMR method for the analysis of the local structural environments in powdered borosilicates $(SiO_2-B_2O_3)$. Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density ma trix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D $11^B$ nutation NMR experiment. The $11^B$ NMR parameters, quadrupole coupling constants $(e^2qQ/h)$ and asymmetry parameters (η), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed.

• Bulletin of the Korean Chemical Society
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• v.19 no.5
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• pp.519-524
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• 1998

In this work, we applied the 1D 11B nutation NMR method for the analysis of the local structural environments in powdered borosilicates (SiO2-B2O3). Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density matrix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D 11B nutation NMR experiment. The 11B NMR parameters, quadrupole coupling constants (e2qQ/h) and asymmetry parameters (η), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed.

• Smart Structures and Systems
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• v.24 no.5
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• pp.659-668
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• 2019

In digital image correlation, speckle image is closely related to the measurement accuracy. A practical global evaluation criterion for speckle image is presented. Firstly, based on the essential factors of the texture image, both the average particle size and image sharpness are used for the assessment of speckle image. The former is calculated by a simplified auto-covariance function and Gaussian fitting, and the latter by focusing function. Secondly, the computation of the average particle size and image sharpness is verified by numerical simulation. The influence of these two evaluation parameters on mean deviation and standard deviation is discussed. Then, a physical model from speckle projection to image acquisition is established. The two evaluation parameters can be mapped to the physical devices, which demonstrate that the proposed evaluation method is reasonable. Finally, the engineering application of the evaluation method is pointed out.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3415-3421
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• 2022

This paper is aimed to find out the impact of the geometrical parameters, mainly the radius and the height of a cylinder, on the SGEMP response including the famous scaling law in the classical cylinder model using a homemade PIC code UNIPIC-3D. We computed the electric fields at the center and at the edge on the emission head face with different radii and heights under normal X-rays incidence. The results show that the electric field will increase with the radius but decrease with the height. We analyze the scaling law that links the electric field product and fluence product, and whereafter an irreconcilable contradiction raises when the radius is changeable, which limits the application range of the scaling law. Moreover, the field-height-radius relation is found and described by a combination of logarithmic and minus one-quarter numerical fitting law firstly. Particle and magnetic field distributions are used to explain all the behaviors of the fields reasonably. All the findings will assist the evaluation of SGEMP response in spacecraft protection.

• Transactions of Materials Processing
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• v.31 no.4
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• pp.194-199
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• 2022

In finite element method (FEM) simulations, constitutive models are widely used and developed to represent a wide range of true stress-strain curves using a small number of modeling parameters. Nevertheless, many studies has been conducted to find a suitable constitutive model and optimal modeling parameters to represent experimentally obtained true stress-strain curves. Therefore, in this study, a new constitutive modeling approach using the combined Swift and Voce model is suggested, and confirmed through comparisons of the experimental results with the FEM simulation results.

• Advances in materials Research
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• v.2 no.1
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• pp.37-49
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• 2013

The transition metal salt doped solid polymer electrolyte [TSPE] were prepared with HPMC as a host polymer. The virgin and doped films were prepared by solution-casting method and investigated using wide angle X-ray scattering method. Micro structural parameters like lattice strain (g%), stacking/twin faults, the average number of unit cells counted in a direction perpendicular to the Bragg's plane (hkl) spacing of (hkl) planes dhkl, crystallite size Ds, distortion width, standard deviation were determined by whole pattern powder fitting (WPPF) method, which is an extension of single order method. It is found that the crystallite size decreases with the increase in the content of $FeCl_3$. This decrease is due to increase in localized breaking of polymer network which also accounts for the amorphous nature of the material. The filler inorganic salt $FeCl_3$ acts as plasticizer. FTIR study also confirms and justifies the interaction between the polymer and in-organic salt in the matrix. Physical properties like mechanical stability and Ac conductivity in these films are in conformity with the X-ray results.

• Steel and Composite Structures
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• v.24 no.2
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• pp.177-189
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• 2017

Hybrid-fiber reinforced concrete (HFRC) may provide much higher tensile and flexural strengths, tensile ductility, and flexural toughness than normal concrete (NC). HFRC slab has outstanding advantages for use as a composite bridge potential deck slab owing to higher tensile strength, ductility and crack resistance. However, there is little information on shear connector associated with HFRC slabs. To investigate the mechanical behavior of the stud shear connectors embedded in HFRC slab, 14 push-out tests (five batches) in HFRC and NC were conducted. It was found that the stud shear connector embedded in HFRC had a better ductility, higher stiffness and a slightly larger shear bearing capacity than those in NC. The experimentally obtained ultimate resistances of the stud shear connectors were also compared against the equations provided by GB50017 2003, ACI 318-112011, AISC 2011, AASHTO LRFD 2010, PCI 2004, and EN 1994-1-1 (2004), and an empirical equation to predict the ultimate shear connector resistance considering the effect of the HFRC slabs was proposed and validated by the experimental data. Curve fitting was performed to find fitting parameters for all tested specimens and idealized load-slip models were obtained for the specimens with HFRC slabs.

• Journal of Preventive Medicine and Public Health
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• v.31 no.3 s.62
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• pp.440-448
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• 1998

In many developed countries, for example, USA, respirator fit testing is required before entering specific work environment to ensure that the respirator worn satisfies a minimum of fit and that the user knows when the respirator fits properly. Unfortunately because we have not fit test regulation in Korea, a lot of workers wearing respirators may be potentially exposed to hazards. This study was conducted to evaluate the fitting performance for respirators and correlation fit factors with facial dimensions of wearers. 110 subjects (70 males, 40 females) were fit tested for three quarter masks, i.e., two domestic-made Mask 2, and Y and one foreign-made Mask T using PortaCount 8020. A facial dimension survey of the same subjects was conducted to develop a facial dimension grids fer correlation fit factors with facial dimension parameters. A facial dimension grid was developed on the basis of face length and lip length for quarter masks. The results obtained were as follows : 1 Fit factors of Mask T were much higher than those of Masks Z, and Y. 2. Males were fitted more properly than females. 3. Male in box 'f' of grid would be adequately fitted Mask Y and male in box 'b', 'e', 'f', 'h' of grid would be sufficiently fitted Mask T. Female in box 'h' of grid may have a good fitting performance for both Mask Y, and T. But subjects in all boxes of grid would be inadequately fitted Mask Z.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.233-236
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• 2002

This study was conducted to estimate the design flood by the determination of best fitting order for LH-moments of the annual maximum series at fifteen watersheds. Parameters of GEV distribution and flood flows of return period n years were derived by the methods of L, L1, L2, L3 and L4-moments. Frequency analysis of flood flow data generated by Monte Carlo simulation was performed by the methods of L, L1, L2, L3 and L4-moments using GEV distribution. Relative Root Mean Square Error (RRMSE), Relative Bias (RBIAS) and Relative Efficiency (RE) using methods of L, L1, L2, L3 and L4-moments for GEV distribution were computed and compared with those resulting from Monte Carlo simulation. At almost all of the watersheds, the more the order of LH-moments and the return periods increased, the more RE became, while the less RRMSE and RBIAS became. Consequently, design floods for the applied watersheds were derived by the methods of L3 and L4-moments among LH-moments in view of high confidence efficiency.

• ETRI Journal
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• v.27 no.2
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• pp.188-194
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• 2005

We report on the improvement of critical dimension (CD) linearity on a photomask by applying the concept of process proximity correction to a laser lithographic process used for the fabrication of photomasks. Rule-based laser process proximity correction (LPC) was performed using an automated optical proximity correction tool and we obtained dramatic improvement of CD linearity on a photomask. A study on model-based LPC was executed using a two-Gaussian kernel function and we extracted model parameters for the laser lithographic process by fitting the model-predicted CD linearity data with measured ones. Model-predicted bias values of isolated space (I/S), arrayed contact (A/C) and isolated contact (I/C) were in good agreement with those obtained by the nonlinear curve-fitting method used for the rule-based LPC.