• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.796-804
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• 2003

The use of fracture mechanics has traditionally concentrated on crack growth under an opening mechanism. However, many service failures occur from cracks subjected to mixed-mode loading. Hence, it is necessary to evaluate the fatigue behavior under mixed-mode loading. Under mixed-mode loading, not only the fatigue crack propagation rate is of importance, but also the crack propagation direction. In modified range 0.3$\leq$a/W$\leq$0.5, the stress intensity factors (SIFs) of mode I and mode II for the compact tension shear (CTS) specimen were calculated by using elastic finite element analysis. The propagation behavior of the fatigue cracks of cold rolled stainless steels (STS304) under mixed-mode conditions was evaluated by using K$\_$I/ and $_{4}$ (SIFs of mode I and mode II). The maximum tangential stress (MTS) criterion and stress intensity factor were applied to predict the crack propagation direction and the propagation behavior of fatigue cracks.

• Elastomers and Composites
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• v.32 no.1
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• pp.20-28
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• 1997

This study have Investigated the effect of various factors related to the physical properties of vulcanizated rubber compounds. rubber type, carbon black type and carbon black loading were selected as main factors and evaluation were tested by tables of orthogonal arrays with 3 factors and 3 levels. rubber types have affected cure time, tensile strength, and $T_g$ as main factor and carbon black loading have affected viscosity, scorch time, maximum torque, hardness, 300% modulus, rebound, heat build-up, $0\;&\;60^{\circ}C$ tangent delta, PICO and CUT/CHIP loss as main factor but the effects of carbon black type have affected only bound rubber content.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2004.11a
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• pp.539-542
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• 2004

Nowadays, High-rise building becomes higher and bigger than ever. As a result, lots of construction materials are needed at the same times. Because of divided diverse process of construction, several different Processes concur simultaneously with complexity of procurement. So, effective construction material supply and lift-up are essential part of the spot. Especially, when ending part of construction, there are much conflict between finishing and equipment materials also problems of folding lift-up. The Purpose of this paper is suggesting better effective lift-up system through analysis of loading factors.

• Steel and Composite Structures
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• v.44 no.6
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• pp.817-828
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• 2022

In this study, considering dissipated energy in fracture process zone (FPZ), a novel criterion based on maximum strain energy release rate (SER) for orthotropic materials is presented. General case of in-plane loading for cracks along the fibers is assumed. According to the experimental observations, crack propagation is supposed along the fibers and the reinforcement isotropic solid (RIS) concept is employed as a superior model for orthotropic materials. SER in crack initiation and propagation phases is investigated. Elastic properties of FPZ are extracted as a function of undamaged matrix media and micro-crack density. This criterion meaningfully links between dissipated energy due to toughening mechanisms of FPZ and the macroscopic fracture by defining stress intensity factors of the damaged zone. These coefficients are used in equations of maximum SER criterion. The effect of crack initiation angle and the damaged zone is considered simultaneously in this criterion and mode II stress intensity factor is extracted in terms of stress intensity factors of damage zone and crack initiation angle. This criterion can evaluate the effects of FPZ on the fracture behavior of orthotropic material. Good agreement between extracted fracture limit curves (FLC's) and available experimental data proves the ability of the new proposed criterion.

• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.556-562
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• 2015

In order to remove the organic substances and the nitrate-nitrogen contained in wastewater, some researchers have studied the simultaneous removal of organics and nitrogen by using different biocathode microbial fuel cells (MFCs). The operating conditions for removing the contaminants in the MFCs are the external resistances, HRTs, the concentration of the influent wastewater, and other factors. This study aimed to determine the effect of the external resistors and organic loading rates, from the changing HRT, on the removal of the organics and nitrogen and on the production of electric power using the Denitrification Biocathode - Microbial Fuel Cell (DNB-MFC). As regards the results of the study, the removal efficiencies of $SCOD_{Cr}$ did not show any difference, but the nitrate-nitrogen removal efficiencies were increased by decreasing the external resistance. The maximum denitrification rate achieved was $129.2{\pm}13.54g\;NO_3{^-}-N/m^3/d$ in the external resistance $1{\Omega}$, and the maximum power density was $3,279mW/m^3$ in $10{\Omega}$. When the DNB-MFC was operated with increasing influent organic and nitrate loading by reducing the HRTs, the $NO_3{^-}-N$ removal efficiencies were increased linearly, and the maximum nitrate removal rate was $1,586g\;NO^3{^-}-N/m^3/d$ at HRT 0.6 h.

• The KSFM Journal of Fluid Machinery
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• v.2 no.3 s.4
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• pp.17-23
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• 1999

In the present numerical analysis, investigation of the effect of blade loadings from design shape on the slip factor variation was studied. Both the Eckardt radial bladed impeller and the backswept impeller were analyzed. In addition, a new design of the blade profile was arbitrarily attempted to generate a center-loading pattern in the original backswept impeller. Three dimensional compressible Navier-Stokes flow analysis with the Baldwin-Lomax turbulence model was applied to get the numerical slip factor at each impeller exit plane using the mass-averaging technique. The numerical slip (actors are in good agreement with the experimental ones and the Wiesner's slip factors deviate further from the numerical and experimental ones in both backswept impellers. Deviation angles and meridional channel loadings are found in no relation with the trend of change of the slip factor. Blade-to-blade loadings in midspan location are, however, found to have a direct relationship, especially at the sections where maximum loadings we to be expected. That information can be utilized in establishing an improved expression for slip factors in the future.

• Journal of Korean Institute of Industrial Engineers
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• v.4 no.2
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• pp.49-58
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• 1978

The purpose of this study was to analyze the actual condition of curriculum composition by factor analysis, then to find out the peculiarity of each factor through factor loading. The method adopted here is to classify and arrange the curricula in accordance with the similarity of each subject, to put it into computer, and to get 16 factors whose eigenvalues are at least 1.00. Consequentely, before the orthogonal rotation 67% of the curricula which have the given factors and maximum factor loading were distributed from factor 1 to factor 4, and after orthogonal rotation 45% of the curricula were distribued.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1538-1545
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• 2005

Theoretical and experimental result studies of the unconfined penetration test (UP) method are conducted to suggest a new test method by improving the UP method for determination of the tensile strength of compacted fine-grained soils. From the theoretical aspect, the tensile strength of the specimen is estimated from the maximum load by the theory of perfect plasticity with assumptions, sufficient local deformability and modified Mohr-Coulomb failure criterion. Experimentally, some factors including relative size of specimen-disc, disc diameter, and loading rate are needed more study, because these factors significantly affect the results of tensile strength. Improvement of the alignement between two discs and specimen in the UP test is also necessary to eliminate the error due to eccentrically loading.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.529-534
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• 1998

To find out an adequate failure criterion in two-dimensional linear elastic crack problems, finite element programs, SED, which determine stress intensity factors $K_I, K_{II}$, crack angle and peak load by the minimum strain energy density failure criterion were developed. In this program, the conventional quadratic isoparametric elements were used in all regions except the crack tip zone where triangular singular elements with 6 nodes were used. The results of SED were compared with the results of those which followed by the maximum circumferential tensile stress criteria and those by the maximum energy release rate criteria and those by Jenq and Shah`s experiments of the same geometry and material properties. The maximum energy release rate criteria were better close to those of the Jenq and Shah`s experiments than the maximum circumferential tensile stress criteria and the minimum strain energy density criteria.

• Journal of Environmental Science International
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• v.21 no.1
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• pp.1-9
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• 2012

A thermal-optical transmittance carbon analyzer has been developed to determine particulate organic (OC) and elemental (EC) carbon. Several analysis factors affecting the sensitivity of OC and EC determination were investigated for the carbon analyzer. Although total carbon (TC) is usually consistent in the determination, OC and EC split is sensitive to adopted analysis protocol. In this study the maximum temperature in oxygen-free He in the analysis was examined as a main cause of the uncertainty. Prior to the sensitivity analysis consistency in OC-EC determination of the carbon analyzer and the uniformity of carbonaceous aerosol loading on a sampled filter were checked to be in acceptable range. EC/TC ratios were slightly decreased with increasing the maximum temperature between $550-800^{\circ}C$. For the increase of maximum temperature from $500^{\circ}C$ to $800^{\circ}C$, the EC/TC ratio was lowered by 4.65-5.61% for TC loading of 13-44 ${\mu}g/cm^2$ with more decrease at higher loading. OC and EC determination was not influenced by trace amount of oxygen in pure He (>99.999%), which is typically used in OC and EC analysis. The facing of sample loaded surface to incident laser beam showed negligible influence in the OC-EC split, but it caused elevated PC fraction in OC for forward facing relative to backward facing.