• Nuclear Engineering and Technology
• /
• v.52 no.6
• /
• pp.1297-1303
• /
• 2020

In this study, nuclear radiation shielding and rigidity parameters of Y (0.1-x)B0.6Bi1.8O3La2x glassy system were investigated in order to determine it's suitability for use as nuclear radiation shielding materials. Therefore, a group of bismuth borate glass samples with La₂O₃ additive were synthesized using the technique of melt quenching. According to the results, the increase of the La₂O₃ additive increases the density of the glass samples and the mass attenuation coefficient (μ_m) values, whereas the half-value layer (HVL) and mean free path (MFP) values decrease. The effective atomic number (Z_eff) is also enhanced with an increment of both mass removal cross section for neutron (Σ_R) and absorption neutron scattering cross section (σ_abs). In addition to the other parameters, rigidity parameter values were theoretically examined. The increase of La₂O₃ causes some other important magnitudes to increase. These are the average crosslink density, the number of bonds per unit volume, as well as the stretching force constant values of these glass samples. These results are in concordance with the increase of elastic moduli in terms of the Makishima-Mackenzie model. This model showed an increase in the rigidity of the glass samples as a function of La₂O₃.

• Journal of Computational Design and Engineering
• /
• v.2 no.4
• /
• pp.218-232
• /
• 2015

Piecewise linear (G01-based) tool paths generated by CAM systems lack $G_1$ and $G_2$ continuity. The discontinuity causes vibration and unnecessary hesitation during machining. To ensure efficient high-speed machining, a method to improve the continuity of the tool paths is required, such as B-spline fitting that approximates G01 paths with B-spline curves. Conventional B-spline fitting approaches cannot be directly used for tool path B-spline fitting, because they have shortages such as numerical instability, lack of chord error constraint, and lack of assurance of a usable result. Progressive and Iterative Approximation for Least Squares (LSPIA) is an efficient method for data fitting that solves the numerical instability problem. However, it does not consider chord errors and needs more work to ensure ironclad results for commercial applications. In this paper, we use LSPIA method incorporating Energy term (ELSPIA) to avoid the numerical instability, and lower chord errors by using stretching energy term. We implement several algorithm improvements, including (1) an improved technique for initial control point determination over Dominant Point Method, (2) an algorithm that updates foot point parameters as needed, (3) analysis of the degrees of freedom of control points to insert new control points only when needed, (4) chord error refinement using a similar ELSPIA method with the above enhancements. The proposed approach can generate a shape-preserving B-spline curve. Experiments with data analysis and machining tests are presented for verification of quality and efficiency. Comparisons with other known solutions are included to evaluate the worthiness of the proposed solution.

• Archives of Plastic Surgery
• /
• v.45 no.4
• /
• pp.357-362
• /
• 2018

Background The most common complication after tendon repair is the development of adhesion, with subsequent rupture. Methods In this study, we present a new method in which the tendon healing contact surface is increased to reduce these complications. The tendons of chickens in groups 1, 3, and 5 were transversely cut and repaired with in the traditional fashion with double-modified Kessler method and 5/0 polypropylene. In the other groups, 3 mm of the tendon was removed from the proximal half of the upper end and from the distal half of the lower end of the tendon, and they were repaired with the modified Kessler method. The tendons of the chickens in groups 1 and 2 were evaluated immediatelly after surgery. Groups 3 and 4 were evaluated at 4 weeks after surgery. Groups 5 and 6 were evaluated at 6 weeks. Results Increases in transient inflammation and connective tissue formation were observed more clearly in the group treated with the new method in histopathological investigations at weeks 4 and 6. The stretching test showed statistically significant differences between groups 3 and 4 (P<0.05) and groups 5 and 6 (P<0.05). Conclusions When repairing tendons with the new method, the healing surface increases and the direction of collagen fibers at the surface changes. Because of these effects, the strength of the tendon healing line increases; we therefore expect that this technique will enable patients to safely engage in early active exercise after the operation, with less risk of tendon rupture.

• Korean Journal of Applied Biomechanics
• /
• v.21 no.5
• /
• pp.645-652
• /
• 2011

The purpose of this study was to analyze, in real time, the glide motion and release motion of domestic athletes and gold and bronze medalists employing the glide technique for the men's shot put at the Daegu World Athletic Championship in 2011. In the glide motion, the Korean athletes had a relatively high body center and shot put heights and lager stretching angles for their hips and knees. In the delivery phase, which shifts to the release phase, the Korean athletes showed slower vertical body center and shot put speeds, and they changed the phase, to the release phase by using a small body angle. In the release phase, the Korean athletes showed differences in their projection speeds and vertical body center speeds. The world-famous players showed high angle speeds, which refer to the composition of the rotation force at the moment of release (body, hip, and shoulder line). In the release phase, the Korean athletes did not have fully stretched hip and knee angles, which might have negatively influenced the vertical speed. Because the Korean athletes showed relatively low projection heights and projection angles. it was found that they need to enhance the muscular power of their, throwing arms and lower limbs.

• Journal of the Korean Institute of Gas
• /
• v.15 no.4
• /
• pp.21-26
• /
• 2011

Type-3 cylinder liner has a limitation of machining the standard specimen for fracture toughness test because it has approximately 5 mm in thickness as well as a curvature. Hence, it needs to be employed a miniature specimen test technique to evaluate fracture toughness of the cylinder liner. In this study, small punch (SP) test method was employed to evaluate fracture toughness of the cylinder liner. Load-displacement curve result measured from the SP test showed that the liner material was failed during membrane stretching in the general SP load-displacement curve. Additionally, it was shown that liner material was isotropic although the amount of plastic deformation was different depending on the direction due to manufacturing process characteristics. Fracture toughness, $J_{Ic}$, was evaluated using the SP test data. The value of fracture toughness obtained was $13.0kJ/m^2$. This value was similar to that of the same kind of materials. Therefore, the fracture toughness evaluated using the SP test data was reasonable.

• Proceedings of the KOSOMBE Conference
• /
• v.1998 no.11
• /
• pp.66-69
• /
• 1998

Comparative genomic hybridization (CGH) is an important molecular cytogenetics technique that maps abnormal copy number of specific DNA sequence of the chromosome. CGH is based on quantitative digital image analysis of ratio images from fluorescently labeled chromosomes. In this paper, we would like to introduce how recently developed image analysis algorithms are used for CGH techniques. To average the ratio profile of each chromosome, binarization, skeletonization, and stretching of chromosome images have been studied. Developed algorithms have been implemented in the karyotyping system ChIPS commercially developed at Biomedlab Co. Ltd.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.5
• /
• pp.891-898
• /
• 1992

When catilever beams rotate about axes perpendicular to the underformed beam's longitudinal axis, their bending stiffnesses change due to the stretching caused by centrifugal inertia forces. Such phenomena result in variations of natural frequencies and mode shapes associated with constant speed rotational motions of the beams. These variations are important in many practical applications such as helicopter blades, turbomachines, and space structures. This paper presents the formulation of a set of linear equations governing the lateral motion of rotating cantilever beams. These equations can be used to provide accurate predictions of the variations of natural frequencies and mode shapes associated with constant speed rotational motions of the beams. These variations are important in many practical applications such as helicopter blades, turbomachines, and space structures. This paper presents the formulation of a set of linear equations governing the lateral motion of rotating cantilever beams. These equations can be used to provide accurate predictions of the variations of natural frequencies and mode shapes due to rotation. This technique is simpler and more consistent than other conventional techniques which are commonly used in the literature.

• Journal of Surface Science and Engineering
• /
• v.36 no.1
• /
• pp.14-21
• /
• 2003

Thin films of ZrO$_2$ and TiO$_2$ were deposited on Si(100) substrates using RF magnetron sputtering technique. To study an influence of the sputtering parameters, systematic experiments were carried out in this work. XRD data show that the $ZrO_2$ films were mainly grown in the [111] orientation at the annealing temperature between 800 and $1000^{\circ}C$ while the crystal growth direction was changed to be [012] at above $1000^{\circ}C$. FT-IR spectra show that the oxygen stretching peaks become strong due to $SiO_2$ layer formation between film layers and silicon surface after annealing, and proved that a diffusion caused by either oxygen atoms of $ZrO_2$ layers or air into the interface during annealing. Different crystal growth directions were observed with the various deposition parameters such as annealing temperature, RF power magnitude, and added $O_2$ amounts. The growth rate of $TiO_2$ thin films was increased with RF power magnitude up to 150 watt, and was then decreased due to a sputtering effect. The maximum growth rate observed at 150 watt was 1500 nm/hr. Highly oriented, crack-free, stoichiometric polycrystalline $TiO_2$<110> thin film with Rutile phase was obtained after annealing at $1000^{\circ}C$ for 1 hour.

• Applied Science and Convergence Technology
• /
• v.25 no.3
• /
• pp.56-60
• /
• 2016

The ALD process is an adequate technique to meet the requirements that come with the downscaling of semiconductor devices. To obtain thin films of the desired standard, it is essential to understand the thermal decomposition properties of the precursors. As such, this study examined the thermal decomposition properties of TEMAHf precursors and its effect on the formation of $HfO_2$ thin films. FT-IR experiments were performed before deposition in order to analyze the thermal decomposition properties of the precursors. The measurements were taken in the range of $135^{\circ}C-350^{\circ}C$. At temperatures higher than $300^{\circ}C$, there was a rapid decrease in the absorption peaks arising from vibration of $Sp^3$ C-H stretching. This showed that the precursors experienced rapid decomposition at around $275^{\circ}C-300^{\circ}C$. $HfO_2$ thin films were successfully deposited by Atomic Layer Deposition (ALD) at $50^{\circ}C$ intervals between $150^{\circ}C$ to $400^{\circ}C$; the deposited films were characterized using a reflectometer, X-ray photoelectron spectroscopy (XPS), Grazing Incidence X-ray Diffraction (GIXRD), and atomic force microscopy (AFM). The results illustrate the relationship between the thermal decomposition temperature of TEMAHf and properties of thin films.

• Geomechanics and Engineering
• /
• v.22 no.5
• /
• pp.415-431
• /
• 2020

In this study, dynamics responses of advanced composite plates resting variable elastic foundations via a quasi-3D theory are developed using an analytical approach. This higher shear deformation theory (HSDT) is included the shear deformation theory and effect stretching that has five unknowns, which is even inferior to normal deformation theories found literature and other theories. The quasi-three-dimensional (quasi-3D) theory accounts for a parabolic distribution of the transverse shear deformation and satisfies the zero traction boundary conditions on the surfaces of the advanced composite plate without needing shear correction factors. The plates assumed to be rest on two-parameter elastic foundations, the Winkler parameter is supposed to be constant but the Pasternak parameter varies along the long side of the plate with three distributions (linear, parabolic and sinusoidal). The material properties of the advanced composite plates gradually vary through the thickness according to two distribution models (power law and Mori-Tanaka). Governing differential equations and associated boundary conditions for dynamics responses of the advanced composite plates are derived using the Hamilton principle and are solved by using an analytical solution of Navier's technique. The present results and validations of our modal with literature are presented that permitted to demonstrate the accuracy of the present quasi-3D theory to predict the effect of variables elastic foundation on dynamics responses of advanced composite plates.