• Structural Engineering and Mechanics
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• v.61 no.6
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• pp.747-754
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• 2017

Exact solutions for stresses for an infinite rectangular plate perforated by two circular holes of different radii subjected to uni-axial or bi-axial uniform loads are investigated using the Airy stress function. The hoop stresses occurring at the edge of the circular hole are computed and plotted. Comparisons are made for the stress concentration factors for several types of loading conditions.

• Korean Journal of Materials Research
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• v.29 no.12
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• pp.764-773
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• 2019

The gas response characteristic toward C₂H₅OH has been demonstrated in terms of copper-vacancy concentration, hole density, and microstructural factors for undoped/Li(I)-doped CuO thin films prepared by sol-gel method. For the films, both concentrations of intrinsic copper vacancies and electronic holes decrease with increasing calcination temperature from 400 to 500 to 600 ℃. Li(I) doping into CuO leads to the reduction of copper-vacancy concentration and the enhancement of hole density. The increase of calcination temperature or Li(I) doping concentration in the film increases both optical band gap energy and Cu2p binding energy, which are characterized by UV-vis-NIR and X-ray photoelectron spectroscopy, respectively. The overall hole density of the film is determined by the offset effect of intrinsic and extrinsic hole densities, which depend on the calcination temperature and the Li(I) doping amount, respectively. The apparent resistance of the film is determined by the concentration of the structural defects such as copper vacancies, Li(I) dopants, and grain boundaries, as well as by the hole density. As a result, it is found that the gas response value of the film sensor is directly proportional to the apparent sensor resistance.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.129-134
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• 2003

The importance of understanding the response of structural composites to impact and CAI cannot be overstated to develop analytical models for impact damage and CAI strength predictions. This paper presents experimental findings observed from quasi-static lateral load tests, low velocity impact tests, CAI strength and open hole compressive strength tests using 3mm thick composite plates ($[45/-45/0/90]_{3s}$ - IM7/8552). The conclusion is drawn that damage areas for both quasi-static lateral load and impact tests are similar and the curves of several drop weight impacts with varying energy levels (between 5.4 J and 18.7 J) fallow the static curve well. In addition, at a given energy the peak force is in good agreement between the static and impact cases. From the CAI strength and open hole compressive strength tests, it is identified that the failure behaviour of the specimens was very similar to that observed in laminated plates with open holes under compression loading. The residual strengths are in good agreement with the measured open hole compressive strengths, considering the impact damage site as an equivalent hole. The experimental findings suggest that simple analytical models for the prediction of impact damage area and CAI strength can be developed on the basis of the failure mechanism observed from the experimental tests.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1649-1656
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• 2010

Internal reorganization energy due to the structural relaxation in hole or electron hopping mechanism is one of the measurements of key indices in designing an organic thin film transistor (OTFT) for flexible display devices. In this study, the reorganization energies of dicyanoanthracenes for the hole and electron transfer were estimated by adiabatic potential energy surface and normal mode analysis method in order to examine the effect on the energies for the positional variation of the cyano substituents in the anthracene as a protocol of acenes to design an organic field effect transistor. The reorganization energy for the hole transfer was reduced considerably upon cyanation of anthracene, especially at the 9,10-positions of anthracene, and the origin of the reduction was interpreted in terms of understanding the coupling of vibrational modes to the hole transfer.

• Structural Engineering and Mechanics
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• v.38 no.3
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• pp.361-384
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• 2011

Earlier studies on hollow-circular rubber bearings, all of which are conducted for steel-reinforced bearings, indicate that the hole presence not only decreases the compression modulus of the bearing but also increases the maximum shear strain developing in the bearing due to compression, both of which are basic design parameters also for fiber-reinforced rubber bearings. This paper presents analytical solutions to the compression problem of hollow-circular fiber-reinforced rubber bearings. The problem is handled using the most-recent formulation of the "pressure method". The analytical solutions are, then, used to investigate the effects of reinforcement flexibility and hole presence on bearing's compression modulus and maximum shear strain in the bearing in view of four key parameters: (i) reinforcement extensibility, (ii) hole size, (iii) bearing's shape factor and (iv) rubber compressibility. It is shown that the compression stiffness of a hollow-circular fiber-reinforced bearing may decrease considerably as reinforcement flexibility and/or hole size increases particularly if the shape factor of the bearing is high and rubber compressibility is not negligible. Numerical studies also show that the existence of even a very small hole can increase the maximum shear strain in the bearing significantly, which has to be considered in the design of such annular bearings.

• International Journal of Control, Automation, and Systems
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• v.3 no.3
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• pp.469-476
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• 2005

Performance of a force-torque sensor is affected significantly by an error signal that is included in the sensor signal. The error sources may be classified mainly into two categories: one is a structural error due to inaccuracy of sensor body, and the other is a noise signal existing in sensed information. This paper presents a principle of 6-axis force-torque sensor briefly, a double-hole structure to be able to improve a structural error, and then a signal conditioning to reduce the effect of a noise signal. The validity of the proposed method is investigated through experimental study, which shows that SIN ratio is improved significantly in our experimental setup, and the sensor can be implemented cheaply with reasonable performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.201-205
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• 2005

This work presents a study on development of a practical and quantitative technique for assessment of the structural health condition by piezoelectric Impedance-based technique associated with longitudinal wave propagaation. The natural frequency of the object has a tendency of frequency shifting according to hole size corresponded to real structure crack and crack size. In order to estimate the damage condition numerically, we suggest the evaluation method of Impedance peak frequency shift hF in this paper.

• Structural Engineering and Mechanics
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• v.13 no.6
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• pp.653-670
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• 2002

In order to ensure the structural dynamic stability of moving liquid-storage containers, the flow motion of interior liquid should be appropriately suppressed by means of mechanical devices such as the disc-type elastic baffle. In practice, the design of a suitable baffle requires a priori the parametric dynamic characteristics of storage containers, with respect to the design parameters of baffle, such as the installation location and inner-hole size, the baffle number, and so on. In this paper, we intend to investigate the parametric effect of the baffle parameters on the transient dynamic behavior of a cylindrical fuel-storage tank in an abrupt vertical acceleration motion. For this goal, we employ the ALE (arbitrary Lagrangian-Eulerian) kinematic description method incorporated with the finite element method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.104-107
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• 2006

Numerical analysis on laminated plates containing an open hole subjected to compression is conducted to predict the damage constitutive behaviour of the plates. A micromechanical constitutive model for unidirectional laminated composites proposed by Liang et a1. (2006), in conjunction with damage models (Karihaloo and Fu, 1989, 1999; Zhao and Weng, 1996, 1997), is implemented into the finite element code ABAQUS to conduct the numerical analysis. The predictions are compared with experiments (Lessard and Chang, 1991) to verify the accuracy of the present analysis.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.1
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• pp.105-111
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• 2003

Wheel for passenger car support the car weight with tires, and they transmit rolling and braking power into the ground. Whittling away at wheel weight is more effective to boost fuel economy than lighting vehicle body structure. A shape of hole in disk is optimized for minimizing the weight of steel wheel. Pro/ENGINEER program is used for formulating the design model, and ANSYS package is selected for analyzing the design model. It has difficulties to interface these commercial software directly. For Combining both programs, response surface methodology is applied to construct approximation functions for maximum stresses and maximum displacements are obtained by full factorial design of five levels. This steel wheel is modeled in 14-inch diameter of rim, and wide parameter of hole in disk is only selected as design variable for reducing the weight of steel whee. PLBA(Pshenichny-Lim-Belegundu-Arora) algorithm, which used the second-order information in the direction finding problem and uses the active set strategy, is used for solving optimization problems.