• Steel and Composite Structures
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• 제19권2호
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• pp.405-416
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• 2015

We proposed the concept of nominal rigidity of a long-span V-shaped rigid frame composite arch bridge, analyzed the effects of structural parameters on nominal rigidity, and derived a theoretical nominal rigidity equation. In addition, we discussed the selection of the arch-to-beam rigidity ratio and its effect on the distribution of internal forces, and analyzed the influence of the ratio on the internal forces. We determined the delimitation value between rigid arch-flexible beam and flexible arch-rigid beam. We summarized the nominal rigidity and arch to beam rigidity ratios of existing bridges. The results show that (1) rigid arch-flexible beam and flexible arch-rigid beam can be defined by the arch-to-beam rigidity ratio; (2) nominal rigidities have no obvious differences among the continuous rigid frame composite arch bridge, V-shaped rigid frame bridge, and arch bridge, which shows that nominal rigidity can reflect the global stiffness of a structure.

• Geomechanics and Engineering
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• 제17권4호
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• pp.323-331
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• 2019

The presence of defects in nature changes the physical parameters of the rock. In this paper, by studying the rock-like specimens with conjugated fractures, the horizontal angle and length are changed, and the physical parameters and failure modes of the specimens under uniaxial compression test are analyzed and compared with the results of simulation analysis. The experimental results show that the peak strength and failure mode of the rock-like specimens are closely related to the horizontal angle. When the horizontal angle is $45^{\circ}$, the maximum value is reached and the tensile failure mode is obtained. The fracture length affects the germination and propagation path of the cracks. It is of great significance to study the failure modes and mechanical properties of conjugated fracture rock-like specimens to guide the support of fractured rock on site.

• 대한수학회논문집
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• 제20권3호
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• pp.611-621
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• 2005

This paper introduces an ID based authenticated two pass key agreement protocol of Smart[4] which used the Weil pairing. We propose other an ID based authenticated two pass key agreement protocol which using the Tate Pairing. We will compare protocol of Smart with this protocol.

• Asian-Australasian Journal of Animal Sciences
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• 제31권2호
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• pp.245-251
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• 2018

Objective: This study was conducted to determine the effects of dietary maifanite supplementation and fecal collection method on the apparent total tract digestibility (ATTD) of calcium (Ca) and phosphorus (P) and blood parameters in growing pigs. Methods: Thirty-six growing barrows (Duroc${\times}$Landrace${\times}$Yorkshire; $27.0{\pm}2.6kg$) were allotted to six dietary treatments with 6 pigs per treatment according to body weight in a completely randomized design. The experimental treatments were: i) Low Ca+cornstarch (2.25%), ii) Low Ca+maifanite (2.25%), iii) Medium Ca+cornstarch (1.42%), iv) Medium Ca+maifanite (1.42%), v) High Ca+cornstarch (0.64%), and vi) High Ca+maifanite (0.64%). Feces were collected by the total collection (TC) and indicator method (IM). At the beginning and the end of the experiment, blood samples were collected from each pig. Results: For the TC method, there were no difference in Ca intake, fecal Ca output, Ca retention and the ATTD of Ca between cornstarch and maifanite diets at the same dietary Ca level. However, urinary Ca excretion was lower (p = 0.01) in pigs fed low Ca diets without maifanite supplementation compared with other dietary treatments. Dietary maifanite supplementation had no effect on the P metabolism in growing pigs. For the IM method, there was no difference in Ca digestibility between cornstarch and maifanite diets at the same dietary Ca level. The ATTD of P was greater (p<0.01) in pigs fed the high Ca diet with maifanite supplementation compared with the high Ca diet with cornstarch treatment. Dietary inclusion of maifanite had no effect on blood parameters in growing pigs. Conclusion: Dietary maifanite supplementation had no effect on the ATTD of Ca and P and serum parameters in growing pigs. The IM resulted in lower digestibility values than the TC method.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.303-304
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• 2006

The mechanical properties of ferrous powder metallurgy (P/M) materials are directly related to their microstructure. Ferrous P/M materials with sufficient hardenability will develop microstructures containing significant percentages of martensite in the as-sintered condition. Recently, sinter-hardening has developed into a highly cost effective production method through hardened P/M parts without the need for additional heat-treatments. This paper reviews the advances of sinter-hardening as well as some key processing parameters such as sintering temperature, cooling rate, tempering required to produce high quality sinter-hardened components. Specific topics including effect of alloying elements, alloying methods, and the Characterization and observation of microstructure are discussed.

• Advances in nano research
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• 제13권3호
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• pp.217-231
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• 2022

This study investigates the geometrical impact on the nanomedicine drug delivery via nanodevices. A nanomotor made of the nanotube carrying the drug as the motor blade is considered in the blood flow. Physical activities change the blood flow, and sports training enhances the blood flow and plays a significant role in the stability of drug delivery devices. This paper studies the impact of geometrical parameters on the nanomotors carrying the nanomedicine. The effect of physical exercise on the dynamic response regarding the stability of drug delivery devices is discussed in detail.

• Asian-Australasian Journal of Animal Sciences
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• 제19권1호
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• pp.13-18
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• 2006

Two different animal models, which differ in whether or not taking maternal genetic effect into account, for estimating genetic parameters of cashmere weight, live body weight, cashmere thickness, staple length, fiber diameter, and fiber length in Inner Mongolia White Cashmere Goat were compared via likelihood ratio test. The results indicate that maternal genetic effect has significant influence on live body weight and cashmere thickness, but no significant influence on the other traits. Using models suitable for each trait, both genetic parameters and trends were analyzed with the MTDFREML program. Heritability estimates from single trait models for cashmere weight, live body weight, cashmere thickness, staple length, fiber diameter and fiber length were found to be 0.30, 0.07, 0.21, 0.29, 0.28 and 0.21, respectively. Genetic correlation estimates from two-trait models between live body weight and all other traits (-0.06~0.07) was negligible, as were those between fiber diameter and all other traits (-0.01~0.03) except cashmere thickness (0.19). Cashmere weight and staple length had moderate to low genetic correlations with other traits (-0.24~0.39 and -0.24~0.34, respectively) except for live body weight and fiber diameter. Cashmere thickness had a strong genetic correlation with fiber length (0.81), and low genetic correlation with other traits (0.19~0.34) except live body weight. Genetic trend analysis suggests that selection for cashmere weight was very effective, which has led to the slow genetic progress of cashmere thickness and fiber length due to their genetic correlations with cashmere weight. The selection for live body weight was not effective, which was consistent with its low inheritability.

• Geomechanics and Engineering
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• 제21권4호
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• pp.357-369
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• 2020

Different from the conventional planar fracture and simplified Newton model, for power-law slurries with a lower water-cement ratio commonly used in grouting engineering, flow model in geological rough fractures is built based on ten standard profiles from Barton (1977) in this study. The numerical algorithm is validated by experimental results. The flow mechanism, grout superiority, and water plugging of pseudo plastic slurry are revealed. The representations of hydraulic grouting properties for JRCs are obtained. The results show that effective plugging is based on the mechanical mechanisms of the fluctuant structural surface and higher viscosity at the middle of the fissure. The formulas of grouting parameters are always variable with the roughness and shear movement, which play a key role in grouting. The roughness can only be neglected after reaching a threshold. Grouting pressure increases with increasing roughness and has variable responses for different apertures within standard profiles. The whole process can be divided into three stationary zones and three transition zones, and there is a mutation region (10 < JRCs < 14) in smaller geological fractures. The fitting equations of different JRCs are obtained of power-law models satisfying the condition of -2 < coefficient < 0. The effects of small apertures and moderate to larger roughness (JRCs > 10.8) on the permeability of surfaces cannot be underestimated. The determination of grouting parameters depends on the slurry groutability in terms of its weakest link with discontinuous streamlines. For grouting water plugging, the water-cement ratio, grouting pressure and grouting additives should be determined by combining the flow conditions and the apparent widths of the main fracture and rough surface. This study provides a calculation method of grouting parameters for variable cement-based slurries. And the findings can help for better understanding of fluid flow and diffusion in geological fractures.

• Smart Structures and Systems
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• 제23권2호
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• pp.107-122
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• 2019

As one of the most important parameters in structural health monitoring, structural frequency has many advantages, such as convenient to be measured, high precision, and insensitive to noise. In addition, frequency-change-ratio based method had been validated to have the ability to identify the damage occurrence and location. However, building a precise enough finite elemental model (FEM) for the test structure is still a huge challenge for this frequency-change-ratio based damage detection technique. In order to overcome this disadvantage and extend the application for frequencies in structural health monitoring area, a novel method was developed in this paper by combining the cross-model cross-mode (CMCM) model updating algorithm with the frequency-change-ratio based method. At first, assuming the physical parameters, including the element mass and stiffness, of the test structure had been known with a certain value, then an initial to-be-updated model with these assumed parameters was constructed according to the typical mass and stiffness distribution characteristic of shear buildings. After that, this to-be-updated model was updated using CMCM algorithm by combining with the measured frequencies of the actual structure when no damage was introduced. Thus, this updated model was regarded as a representation of the FEM model of actual structure, because their modal information were almost the same. Finally, based on this updated model, the frequency-change-ratio based method can be further proceed to realize the damage detection and localization. In order to verify the effectiveness of the developed method, a four-level shear building was numerically simulated and two actual shear structures, including a three-level shear model and an eight-story frame, were experimentally test in laboratory, and all the test results demonstrate that the developed method can identify the structural damage occurrence and location effectively, even only very limited modal frequencies of the test structure were provided.

• Geomechanics and Engineering
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• 제36권5호
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• pp.427-440
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• 2024

This study concentrates on the 301 comprehensive caving working face, notable for its considerable mining height. The roof model is established by integrating prior geological data and the latest borehole rock stratum's physical and mechanical parameters. This comprehensive approach enables the determination of lithology, thickness, and mechanical properties of the roof within 50 m of the primary mining coal seam. Utilizing the transfer rock beam theory and incorporating mining pressure monitoring data, the study delves into the geometric parameters of the direct roof, basic roof movement, and roof pressure during the initial mining process of the 301 comprehensive caving working face. The direct roof of the mining working face is stratified into upper and lower sections. The lower direct roof consists of 6.0 m thick coarse sandstone, while the upper direct roof comprises 9.2 m coarse sandstone, 2.6 m sandy mudstone, and 2.8 m medium sandstone. The basic roof stratum, totaling 22.1 m in thickness, includes layers such as silty sand, medium sandstone, sandy mudstone, and coal. The first pressure step of the basic roof is 61.6 m, with theoretical research indicating a maximum roof pressure of 1.62 MPa during periodic pressure. Extensive simulations and analyses of roof subsidence and advanced abutment pressure under varying working face lengths. Optimal roof control effect is observed when the mining face length falls within the range of 140 m-155 m. This study holds significance as it optimizes the working face length in thick coal seams, enhancing safety and efficiency in coal mining operations.