• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1187-1193
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• 2002

Anodic bonding process has been quantitatively evaluated based on the Taguchi analysis of the interfacial fracture toughness, measured at the interface of anodically bonded silicon-glass bimorphs. A new test specimen with a pre-inserted blade has been devised for interfacial fracture toughness measurement. A set of 81 different anodic bonding conditions has been generated based on the three different conditions for four different process parameters of bonding load, bonding temperature, anodic voltage and voltage supply time. Taguchi method has been used to reduce the number of experiments required for the bonding strength evaluation, thus obtaining nine independent cases out of the 81 possible combinations. The interfacial fracture toughness has been measured for the nine cases in the range of 0.03∼6.12 J/㎡. Among the four process parameters, the bonding temperature causes the most dominant influence to the bonding strength with the influence factor of 67.7%. The influence factors of other process parameters, such as anodic voltage and voltage supply time, bonding load, are evaluated as 18%, 12% and 2.3%, respectively. The maximum bonding strength of 7.23 J/㎡ has been achieved at the bonding temperature of 460$\^{C}$ with the bonding load of 45gf/㎠, the applied voltage of 600v and the voltage supply time of 25minites.

• Imaging Science in Dentistry
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• v.37 no.1
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• pp.53-59
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• 2007

Purpose : Bone mineral density (BMD) and bone microarchitecture are important determinants for bone strength. Recently micro-CT have provided possibilities for measuring a variety of structural indices to characterize bone microarchitecture. The objective of this study was to compare the BMD and micro-CT parameters with Young's modulus calculated by finite element analysis (FEA) for the evaluation of bone strength. Materials and Methods Bone specimens were obtained from the 18 female rabbits aged 16 weeks. Of those, 36 samples (right and left femur) were selected for 3D micro-CT analysis $(ANT^{TM},\;SKYSCAN,\;Belgium)$ and BMD by PIXlmus 2 (GE Lunar Co. USA). Five microstructural parameters of micro-CT, such as trabecular thickness (Tb.Th), bone specific surface (BS/BV), percent bone volume (BV/TV), structure model index (SMI) and degree of anisotropy (DOA) were studied. Young's modulus was obtained by software program (ANSYS 9.0, ANSYS Inc, Canonsburg, PA) based on micro-CT three dimensional images. Results : Young's modulus assessed by FEA correlated significantly with Tb.Th, BV/TV, BS/BV and SMI respectively. Young's modulus showed higher correlation with these rnicrostructural parameters of micro-CT than BMD. Microstructural parameters except DOA showed significant correlations within the examined group. Conclusion The microarchitectural parameters o( micro-CT and BMD represented some informations in the evaluation of bone strength assessed by FEA.

• Journal of Korean Society of Steel Construction
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• v.14 no.6
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• pp.813-822
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• 2002

The squash strength and design strength are smaller than the experimental strength of square shaped concrete-filled steel tubular columns in a short concentrically loaded column. This study presents an evaluation procedure accounting for the confining effect of concrete. For the purpose of evaluating a confining effect of concrete, the 3D finite element method was used. The influence of parameters, width-thickness ratios, strength of the concrete and the yield strength of the steel, were examined. The suggested evaluation procedure that assembled three parameters was compared with previous experimental results. Also, the tendency of the confining effect of concrete was examined in the three types of load application.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.143-150
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• 1998

The evaluation of joint fatigue strength of light weight materials for electrical vehicle body has been performed through single lap joint tests with the design parameters such as joint style, adherend, bonding overlap length and bonding thickness. Fatigue strength was evaluated through 5-Hz, tension-tension, load controlled test with the stress ratio zero value. It is experimentally observed that fatigue strength of joint increases for the increase of overlap length. The combinations of Al-Al and Al-FRP adherends show that fatigue strength of joint is hardly changed for the increase of bonding thickness, but FRP-FRP adherend specimen shows that fatigue strength of joint increases after decreases for the increase of bonding thickness. Al-Al adherend specimen has much higher fatigue length than Al-FRP and FRP-FRP adherend specimens. Riveting at adgesive bonded joint gives little effect on fatigue strength.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.673-678
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• 2010

In this paper, the limit load of granular materials was evaluated considering unsaturated shear strength. The unsaturated shear strength parameters were estimated using the results from triaxial compression test and soil-water characteristic curves test. In addition, the limit load of different rates of materials was compared. Also, two important design parameters, yield and failure load were defined utilizing 2-D nonlinear finite element analysis respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.166-173
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• 1998

The evaluation of joint fatigue strength of light weight materials for an electrical vehicle body has been performed through T-peel joint tests with the design parameters such as joint style, adherend type, adherend thickness, adhesive thickness, and various adhesives. Fatigue strength was evaluated through 5-Hz, tension-tension, load controlled test with the zero stress ratio. It was observed that the fatigue strength of the joint increases with the increase of the adherend thickness. With the increase of the adhesive thickness, however, the fatigue strength of the joint increases insignificantly. An aluminum-FRP adherend combination shows much higher fatigue strength than an aluminum-aluminum adherend combination. The results of fatigue tests were found to be consistent with those of static tests.

• Journal of the Korean Society of Safety
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• v.13 no.2
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• pp.122-129
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• 1998

A field experiment was performed to analyze the properties of SFRS(steel fiber reinforced shotcrete) against WMRS(wire mesh reinforced shotcrete) with some experimental parameters. The parameters were reinforcing methods(steel fiber and wire mesh), steel fiber contents(0.5%, 0.75%, and 1.0%), silica fume contents(0.0% and 10.0%), spraying thicknesses of layer(10㎝, 8㎝, and 6㎝), and spraying parts(side wall, shoulder, and crown). According to the analyzed results, the mechanical properties of SFRS such as compressive strength, flexural strength, and load-carrying capacity after cracks were improved. And the economic evaluation was also performed on the basis of the required thickness of the layer and other researcher's results for rebound ratios. From the results of this tests, it is found that the traditional WMRS may be substituted by the SFRS in the viewpoint of the economic evaluation as well as the mechanical properties. In additions, the silica fume, even if it is very expensive, can significantly improve the mechanical properties of the shotcrete regardless of mixing with or without the steel fiber.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.505-508
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• 1999

To evaluate the strength of square reinforced concrete shot columns, thirty specimens were manufactured and tested under monotonically increasing concentric compression. The test parameters included the volumetric ratio of transverse reinforcement($\rho$h = 0.49~2.65), and concrete compressive strength (234, 437, 704 kgf/$\textrm{cm}^2$). Test results are shown that : (1) Behavior of high -strength concrete column is improved by providing increased volumetric ratio; and (2) ACI, Eq. is not proper to evaluate HSC short column strength.

• Journal of the Korean Geosynthetics Society
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• v.8 no.3
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• pp.25-34
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• 2009

Determination of design parameters of composite ground including colluvial soil layer is far difficult because the maximum particle size of such a soil is remarkably large and particle distribution may vary from area to area. The stress-strain behavior of colluvial soils is in fact dependent upon the engineering characteristics at the boundary between coarse and fine materials. However, strength parameters are in general determined based on the characteristics of fine material, which causes an underestimation of such parameters. In this study, strength parameters of colluvial soil are evaluated by means of BIMROCK model curve. In addition, limit equilibrium analysis is carried out to verify the rational shear strength evaluation.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.87-93
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• 1997

The bonding strength evaluation of light weight materials for electrical vehicle applications has been performed through single lap joint tests in which the design parameters such as fillet, joint style, adherend, bonding overlap length,bonding thickness, and environmental condition(soaking time in $25^{\circ}C$ water) are considered. It is experimentally oberved that lap shear strength of joint increases for higher fillet height, longer overlap length, and thinner bonding layer thickness. Al-Al adherend combination shows much higher lap shear strength than AL-FRP and FRP-FRP adherend combinations. Riveting at adhesive bonded joint of AL-AL adherend combination makes lap shear strength decrease. Effect of soaking time on lap shear strength is negligible.