• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.3 s.22
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• pp.101-110
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• 2005

In this paper, the experiments have been conducted to measure the residual velocity for 3.5g steel ball perforating light weight metal plates of aluminum alloy and magnesium alloy. Non-contact electro-magnetic sensors were used to measure the velocity of steel ball before/after perforating plates. The thicknesses of specimens used were about 2.8mm and 4.8mm. The impact velocities of steel ball were from 662m/s to 3594m/s. With same conditions, numerical analysis using Autodyn 2D has been conducted. The results of numerical analysis corresponded with those of experiments. Also, It is suggested that the difference between the residual velocity of experiment or numerical analysis and that of THOR experimental equation of BRL grew smaller as the impact velocity were increased.

• Journal of the Korea Furniture Society
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• v.28 no.4
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• pp.259-267
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• 2017

Furniture should change according to space. Therefore, it is important that the flexibility of the furniture, the functional efficiency, the economical efficiency and the convenience of the furniture of today. These characteristics are also important for seminar tables that are used temporarily by a large number of people. The seminar furniture currently in use has no shielding plate, there are two forms of table and shielding plate folding table. Therefore, in this research, furniture design and product development that can complement the shortcomings of the seminar furniture currently in use were done. Analysis of problems through overseas investigation and domestic market research, design planning and design, and prototyping. We have sought to optimize the volume by applying the characteristics of RTA furniture to develop a lightweight, lightweight, lightweight, easy to install and easy to use shielding plate, and open and closed system. Basically developed two types of shielding board seminar table basic shape and Roll Screen type, we expanded the scope of application such as each color and pattern. In order to reduce the weight, we replaced the parts such as anchor bolts and hinges and the shielding plate with Roll Screen and pursued volume optimization. As a result of this research, it is expected that the system of mechanisms such as packaging standardization and damage prevention for weight reduction and volume optimization will contribute to building competitiveness by domestic office prefabricated furniture industry's original technology.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.574-582
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• 1999

This paper discusses the multi-level optimization method in dynamic optimization problems through stiffened plate of ship structures. In structural optimization the computational cost increases rapidly as the number of design variables increases. And we need a great amount of cal-culation and time on problems of modified dynamic characteristics of large and complicated struc-tures. In this paper the multi-level optimization is proposed which decreases computational time and cost. the dynamic optimum designs of stiffened plate that control the natural frequency and minimize weight subjected to constraints condition are derived. The way to apply the multi-level optimization methods in this study follow: In the first step the dynamic characteristics is controlled for the two-dimensional model of stiffened plate by sensitivity analysis and quasi-least squares methods. In the second step the cross-section of the stiffener is decided so that the weight is minimized under needed constraints by the steepest descent or ascent method. In the third the three-dimensional model is made based on the results of the first step and the second step confirmation and finer tuning of the objective function are carried out. It is shown that the results are effective in the optimum modification for dynamic characteristics of the stiffened plate.

• Journal of Hydrogen and New Energy
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• v.22 no.6
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• pp.827-834
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• 2011

Epoxy/graphite/expanded graphite composites have been prepared in various weight ratios and thermal degradation and electrical properties were estimated in order to use for the bipolar plate materials in PEMFC. Thermogravimetric analysis (TGA) showed that the epoxy/graphite system cured by a curing agent GX-533 was most proper because its weight loss until $80^{\circ}C$ at which PEMFC would be operated was 0.3 wt%, and differential scanning calorimetry (DSC) analysis showed its cure temperature would be sufficient at $80^{\circ}C$. The activation energy for the cure reaction was 132.0 kJ/mol and the pre-exponential factor was $1.76{\times}10^{17}min^{-1}$. Electrical conductivity on the surface of the bipolar plate prepared under a pressure of 200 $kgf/cm^2$ was increased from 4 to 25 $S/cm^2$ by increasing expanded graphite (EG) content from 50 phr to 90 phr. The percolation threshold was initiated around 75 phr and the corrosion rate at 80 phr was 1.903 $uA/cm^2$.

• Structural Engineering and Mechanics
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• v.85 no.4
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• pp.445-459
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• 2023

The current investigation is the first endeavor to apply the full layerwise finite element method (FEM) in free vibration analysis of functionally graded (FG) composite plates reinforced with graphene nanoplatelets (GPLs) in thermal environment. Unlike the equivalent single-layer (ESL) theories, the layerwise FEM focuses on all three-dimensional (3D) effects. The GPLs weight fraction is presumed invariable in each layer but varies through the plate thickness in a layerwise model. The modified Halpin-Tsai model is employed to acquire the effective Young's modulus. The rule of mixtures is applied to specify the effective Poisson's ratio and mass density. First, the current method is validated by comparing the numerical results with those stated in the available works. Next, a thorough numerical study is performed to examine the influence of various factors involving the pattern of distribution, weight fraction, geometry, and size of GPLs, together with the thickness-to-span ratio, thermal environment, and boundary conditions of the plate, on its free vibration behaviors. Numerical results demonstrate that employing a small percentage of GPL as reinforcement considerably grows the natural frequencies of the pure epoxy. Also, distributing more square-shaped GPLs, involving a smaller amount of graphene layers, and vicinity to the upper and lower surfaces make it the most efficient method to enhance the free vibration behaviors of the plate.

• Earthquakes and Structures
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• v.26 no.4
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• pp.251-259
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• 2024

In this paper, the thermal post-buckling behavior of graphene platelets reinforced metal foams (GPLRMFs) plate with initial geometric imperfections on nonlinear elastic foundations are studied. First, the governing equation is derived based on the first-order shear deformation theory (FSDT) of plate. To obtain a single equation that only contains deflection, the Galerkin principle is employed to solve the governing equation. Subsequently, a comparative analysis was conducted with existing literature, thereby verifying the correctness and reliability of this paper. Finally, considering three GPLs distribution types (GPL-A, GPL-B, and GPL-C) of plates, the effects of initial geometric imperfections, foam distribution types, foam coefficients, GPLs weight fraction, temperature changes, and elastic foundation stiffness on the thermal post-buckling characteristics of the plates were investigated. The results show that the GPL-A distribution pattern exhibits the best buckling resistance. And with the foam coefficient (GPLs weight fraction, elastic foundation stiffness) increases, the deflection change of the plate under thermal load becomes smaller. On the contrary, when the initial geometric imperfection (temperature change) increases, the thermal buckling deflection increases. According to the current research situation, the results of this article can play an important role in the thermal stability analysis of GPLRMFs plates.

• Asian-Australasian Journal of Animal Sciences
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• v.3 no.3
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• pp.155-159
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• 1990

The growth of lean from nine wholesale cuts in relation to the total lean weight in carcass side were evaluated with three allometric equations for 18 Najdi male camels slaughtered at 8, 16 and 26 months of age. The allometric growth coefficients indicated that as the camels grew, weights of lean form brisket and flank cuts increased relatively more rapidly than the total lean in carcass side (${\beta}$ >1.1) and that weights of lean from wholesale shoulder and rump cuts increased relatively less rapidly (${\beta}$ <.9) than the total lean weight from carcass side. The growth coefficients for the lean in the thoracic limb and pelvic limb showed a dorsoventral rise in the growth impetus, with coefficients for the thoracic limb correspondingly higher than those of pelvic limb. The growth coefficients for the lean from shoulder, rib, flank and leg cuts increased (p<.01) with increased weight of total lean in carcass side, whereas it decreased with increased total lean weight in carcass side for the lean in neck, brisket, plate, loin and rump cuts. At a constant weight of total lean in carcass side, older camels had larger coefficients for lean in neck, brisket, rump, flank and leg cuts, but had smaller coefficients for lean in shoulder, rib, plate and loin cuts.

• The Journal of Pediatrics of Korean Medicine
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• v.17 no.2
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• pp.1-13
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• 2003

Objectives: The purpose of this study was to suggest a scientific method for measurement of children's growth development. Ultrasonic image of calcaneus bone has some advantages that it is harmless to human body and apply a new imaging analysis algorithm. it can be used for the diagnosis of growth analyzed the opening degree of growth plate and bone density. Methods: This clinical study have been carried out with the 57 case(male 24, female 33) of the children aged 5 to 14 years old who visited in Department of Pediatrics, Dongguk university Bundang Oriental Hospital. Bone maturity is measured by the opening degree of growth plate and bone density in ultrasonic image of calcaneus bone This study were designed to investigate the relationship of the development of children and the calcaneus bone maturity. Result: The opening degree of growth plate was no change in aged 5-10 years for male and 5-9 years for female but decreased significantly from aged 11 years for male and 10 years for female. the bone density was no change in aged 5-12 years for male and 5-11 years for female but increased significantly from aged 13 years for male and 12 years for female. it was confirmed that bone maturity in female is more rapid than in male. The opening degree of growth plate of claclneus bone was correlated with age, height, weight. The bone density was correlated with age, height, weight, BMI in this suudy(P<0.001) Conclusion: The opening degree of growth plate and bone density of calcaneus bone are sufficient diagnostic worth as an index to predict adolescent growth.

• Steel and Composite Structures
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• v.42 no.2
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• pp.277-288
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• 2022

A novel flat steel plate-concrete-corrugated steel plate (FS-C-CS) sandwich panel was proposed for resisting impact load. The failure mode, impact force and displacement response of the FS-C-CS panel under impact loading were studied via drop-weight impact tests. The combined global flexure and local indentation deformation mode of the FS-C-CS panel was observed, and three stages of impact process were identified. Moreover, the effects of corrugated plate height and steel plate thickness on the impact responses of the FS-C-CS panels were quantitatively analysed, and the impact resistant performance of the FS-C-CS panel was found to be generally improved on increasing corrugated plate height and thickness in terms of smaller deformation as well as larger impact force and post-peak mean force. The Finite Element (FE) model of the FS-C-CS panel under impact loading was established to predict its dynamic response and further reveal its failure mode and impact energy dissipation mechanism. The numerical results indicated that the concrete core and corrugated steel plate dissipated the majority of impact energy. In addition, employing end plates and high strength bolts as shear connectors could prevent the slip between steel plates and concrete core and assure the full composite action of the FS-C-CS panel.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.05
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• pp.74-78
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• 1991

Conventional compression bone fracture plates sometimes cause osteoporosis under the plate due to their high rigidity which in turn transfer physiological load mostly through the plates and screws. In order to prevent the osteopenia we have designed a system which have a viscoelastic washer between plate and screw head. The washer is made of a biocompatible ploymer (untra high molecular weight polyethylene, UHMWPE). Three-dimensional finite element meshes of the human femur with the conventional and new concept bone plate ere generated and the comparative stress analyses are performed with static half-stance loading condition. The results of analyses showed that could reduce the stress shielding effect compared with the conventional plate.