• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.4
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• pp.37-44
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• 1991

A powerful analytical procedure and strain energy analysis to investigate the free vibration of antisymmetric cross-ply laminated plates, having one pair of opposite edges simply supported, are develped on the basis of the Yang, Norris abd Stavsky (YSN) theory. The equation of motion of the plate are solved by the use of collation method. A range of results are presented for plates to show the effects of modulus ratio and number of layers on natural frequency. In addition, an analysis of the strain energy distributions is used as an aid for the better understanding of the vibration characteristics of the plates.

• Smart Structures and Systems
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• v.22 no.1
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• pp.27-40
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• 2018

The governing equations of motion are derived for analysis of a sandwich microbeam in this paper. The sandwich microbeam is including an elastic micro-core and two piezoelectric micro-face-sheets. The microbeam is subjected to transverse loads and two-dimensional electric potential. Higher-order sinusoidal shear deformation beam theory is used for description of displacement field. To account size dependency in governing equations of motion, strain gradient theory is used to mention higher-order stress and strains. An analytical approach for simply-supported sandwich microbeam with short-circuited electric potential is proposed. The numerical results indicate that various types of parameters such as foundation and material length scales have significant effects on the free vibration responses and dynamic results. Investigation on the influence of material length scales indicates that increase of both dimensionless material length scale parameters leads to significant changes of vibration and dynamic responses of microbeam.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.345-352
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• 2000

It is very important to evaluate the reliable nonlinear modulus characteristics of soils not only in the analysis of geotechnical structures under working stress conditions but also for the soil dynamic problems. For the evaluation of modulus characteristics of soils, various tests have been mostly employed in laboratory. However, different testing techniques are likely to have different ranges of reliable strain measurements, different applied stress level, and different loading frequencies, and the modulus of soils can be affected by these variables. For reliable evaluation, therefore, those effects on the modulus need to be considered, and measured values should be effectively adjusted to actual conditions where the soil is working. In this paper, to evaluate the modulus characteristics of soils, laboratory testing such as free-free resonant column (FF-RC), resonant column (RC), torsional shear (TS), static TX, and cyclic M/sub R/ tests were performed. The effects of strain amplitude, loading frequency, loading cycles, confining pressure, density, and water content on modulus were investigated. It is shown that the FF-RC test, which is simple and inexpensive testing technique, can provide a reliable estimation of small strain Young's modulus (E/sub max/), and the modulus evaluated by various laboratory tests are comparable to each other fairly well when the effects of these factors are properly taken into account.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.3 s.73
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• pp.313-322
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• 2006

In the genetic algoricm (GA) based damage detection methods using vibration of structures, the selection of modal properties is important to improve the accuracy of damage detection. The objective of this study is to improve the accuracy of damage detection using natural frequency and modal strain energy, The following approaches are used to achieve the goal. First, modal strain energy is formulated and a new GA-based damage detection technique using natural frequency and modal strain energy is proposed. Next, to verify the efficiency of proposed technique, damage scenarios for free-free beam are designed and vibration modal tests of the target structure are conducted. Finally, the feasibility of the proposed technique is verified in comparison with other GA-based damage detection technique using natural frequency and mode shape.

• Journal of Plant Biotechnology
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• v.47 no.2
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• pp.118-123
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• 2020

The black seed coat of soybeans contain anthocyanins which promote health. However, mature soybean seeds contain anti-nutritional factors like lipoxygenase, lectin and Kunitz Trypsin Inhibitor (KTI) proteins. Furthermore, these seeds can be used only after the genetic elimination of these proteins. Therefore, the objective of this study was to develop novel soybean genotypes with black seed coat and triple recessive alleles (lx1lx1lx2lx2lx3lx3, titilele) for lipoxygenase, lectin, and KTI proteins. From a cross of parent1 (lx1lx2lx3/lx1lx2lx3, ti/ti, Le/Le) and parent2 (lx1lx2lx3/lx1lx2lx3, Ti/Ti, le/le), 132 F₂ seeds were obtained. A 3:1 segregation ratio was observed during F₂ seed generation for the inheritance of lectin and KTI proteins. Between a cross of the Le and Ti genes, the observed independent inheritance ratio in the F₂ seed generation was 9: 3 : 3 : 1 (69 Le_Ti_: 32 leleTi_: 22 Le_titi: 9 leletiti) (χ²=2.87, P=0.5 - 0.1). From nine F₂ seeds with triple recessive alleles (lx1lx1lx2lx2lx3lx3, titilele genotype), one novel strain posessing black seed coat, and free of lipoxygenase, lectin and KTI proteins, was selected. The seed coat color of the new strain was black and the cotyledon color of the mature seed was green. The weight of 100 seeds belonging to the new strain was 35.4 g. This black soybean strain with lx1lx1lx2lx2lx3lx3, titilele genotype is a novel strain free of lipoxygenase, lectin, and KTI proteins.

• Ceramist
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• v.23 no.1
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• pp.89-100
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• 2020

Abnormally large electromechanical strain properties have been reported in bismuth-based piezoelectric ceramics, which cast a promise for replacing the market-dominating PZT-based piezoelectric ceramics in actuator applications. In spite of these large strains in bismuth-based piezoelectric ceramics, there still remains a critical issue for its safe transfer to practical applications, representatively, a relatively high operating field required to obtain the large strain properties. To overcome the challenge, much attention has been paid to so-called 0-3(or 3-0) type ceramic/ceramic composite approach to better tailoring the strain properties of bismuth-based piezoelectric ceramics. The approach turns out to be highly effective, leading to a drastic decrease in the operating electric field for these materials. Besides, both extensive and intensive search for the related mechanism revealed that the reduction in the operating electric field is largely due to the contribution from polarization coupling or strain coupling model between two different ceramics. This article reviews the status of the art in the development of novel ceramic/ceramic composites to make large incipient piezostrains in bismuth-based lead-free piezoelectric ceramics practical.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.396-400
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• 2006

We studied the influences of open cracks in free vibrating beam with rectangular section using a numerical model. The crack was assumed to be single and always open during the free vibration and equivalent bending stiffness of a cracked beam was calculated based on the strain energy balance. By Galerkin's method, the frequencies of cantilever beam could he obtained with respect to various crack depths and locations. Also, the experiments on the cracked beams were carried out to find natural frequencies. The cracks were initiated at five locations and the crack depths were increased by five steps at each location. The experimental results were compared with the numerical results and the comparison results were discussed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.75-80
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• 1998

Dynamic measurements are used rather sparingly to determine the elastic moduli of rock cores and modulus values are not much utilized in design practices. The reason seems to result from the general perception that values obtained by dynamic measurement are much higher (about 10 time) than those determined statically. This paper presents results from dynamic and static tests on rock cores. One of the findings is that both moduli determined by statically and dynamically on a solid rock core agrees well at the same-strain. At different strain levels, the ratio between dynamic and static modult widely varies depending upon micro-cracks and discontinuites of rock cores.

• Korean Journal of Metals and Materials
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• v.46 no.9
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• pp.572-576
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• 2008

Elastostatic compression tests were carried out on amorphous alloys to evaluate their energy absorption capability during homogeneous deformation at room temperature. Experiments demonstrated that a compressive stress below the global yield imposed on amorphous alloys for extended periods causes homogeneous plastic strain associated with the irreversible structural disordering. During the disordering process, free volume was created, dissipating the externally applied strain energy and the rate of creation was found to converge to a saturated value. We evaluated the capability of energy absorption of amorphous alloys during homogeneous deformation using recent theories on the evolution of the structural state.

• Structural Engineering and Mechanics
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• v.81 no.3
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• pp.259-266
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• 2022

Based upon differential quadrature method (DQM) and nonlocal strain gradient theory (NSGT), an investigation on the free vibrations of 2D plate systems with nano-dimensions has been provided taking into account the effects of different mechanical loadings. In order to capture different mechanical loadings, a general form of variable compressive load applied in the axial direction of the plate system has been introduced. The studied plate has been constructed from two types of particles which results in graded material properties and nanoscale pores. The established formulation for the plate is in the context of a novel shear deformable model and the equations have been solved via a semi-numerical trend. Presented results indicate the prominence of material composition, nonlocal coefficient, strain gradient coefficient and boundary conditions on vibrational frequencies of nano-size plate.