• Current Photovoltaic Research
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• v.4 no.4
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• pp.140-144
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• 2016

In this paper, core-shell structure of nickel/gold (Ni/Au) conductive layer on poly-methyl-methacrylate (PMMA) micro-ball was fabricated and its conduction property was investigated. Firstly, PMMA micro-ball was synthesized by using dispersion polymerization method. Size of the ball was $2.8{\mu}m$ within ${\pm}7%$ deviation, and appropriate elastic deformation of the PMMA micro-ball ranging from 31 to 39% was achieved under 3 kg pressure. Also, 200 nm thick Ni/Au conductive layer was fabricated on the PMMA micro-ball by uniformly depositing with electroless-plating. Adhesion of the conductive layer was optimized with help of surface pre-treatment, and the layer adhered without peeling-off despite of thermal expansion by collision with accelerated electrons. Composite paste containing core-shell structured particles well cured at low temperature of $130^{\circ}C$ while pressing the test chip onto the substrate to make electrical contact, and electrical resistance of the conductive layer showed stable behavior of about $6.0{\Omega}$. Thus, it was known that core-shell structured particle of the Ni/Au conductive layer on PMMA micro-ball was feasible to flexible electronics.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.2
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• pp.159-168
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• 2010

This paper presents a mathematical model and simulation method for investigating the performance of set net systems and fish cage systems influenced by currents and waves. Both systems consist of netting, mooring ropes, a floating collar and sinkers. The netting and ropes were considered flexible structures and the floating collar was considered an elastic structure. Both were modeled on a mass-spring model. The structures were divided into finite elements and mass points were placed at the mid-point of each element, and the mass points were connected by mass-less springs. Each mass point was subjected to external and internal forces and the total force was calculated at every integration step. An implicit integration scheme was used to solve the nonlinear dynamic system. The computation method was applied to dynamic simulation of actual systems simultaneously influenced by currents and waves in order to evaluate their practicality. The simulation results improved our understanding of the behavior of the structure and provided valuable information concerning the optimized design of set net and fish cage systems exposed to an open ocean environment.

• Ocean Systems Engineering
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• v.1 no.1
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• pp.17-28
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• 2011

The purpose of this paper is to demonstrate the efficacy of modeling a surface effect ship's air-cushion flexible seal utilizing a two-dimensional beam under steady state conditions. This effort is the initial phase of developing a more complex three-dimensional model of the air-seal-water fluid-structure interaction. The beam model incorporates the seal flexural rigidity and mass with large deformations while assuming linear elastic material response. The hydrodynamic pressure is derived utilizing the OpenFOAM computational fluid dynamic (CFD) solver for a given set of steady-state flow condition. The pressure distribution derived by the CFD solver is compared with the pressure required to deform the seal beam model. The air pressure, flow conditions and seal geometry are obtained from experimental analysis. The experimental data was derived from large-scale experimental tests utilizing a test apparatus of a canonical surface effect ship's flexible seal in a towing tank over a variety of test conditions.

• Journal of Aerospace System Engineering
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• v.7 no.2
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• pp.1-7
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• 2013

Recently, there are a number of studies over dynamic analysis for minimizing vibration of flexible structures such as solar panel for agility of high-agility satellite. The traditional studies perform dynamic analysis of a solar panel assumed as rigid structure since the stiffness of solar panel is higher than the stiffness of solar panel's hinge spring. However, there are vibrations that have modes of bending and torsion when high-agility satellite rotate speedily. This vibrations result in delaying safety time of satellite or degrading image quality. This paper presents dynamic analysis's technique of satellites including the spring hinge of solar panel and flexible structural solar panel's effects described as the linear equation of motion using Lagrange's theorem, and verifies the validity of an established dynamic analysis's technique of satellites by comparing the finite element method. In addition high-agility satellite's dynamic characteristics of a torque profile are analyzed from the established dynamic analysis's technique of satellites.

• Current Photovoltaic Research
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• v.2 no.3
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• pp.79-83
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• 2014

Dye-sensitized solar cells (DSSCs) are applied in the emerging fields of building integrated photovoltaic and electronics integrated photovoltaic like small portable power sources as demands are increased with characteristic advantages. Highly flexible dye-sensitized solar cells (DSSCs) prepared on single stainless steel mesh were proposed in this paper. Single mesh DSSCs structure utilizing the spraying the chopped glass paper on the surface treated stainless steel mesh for integrating the space element and the electrode components, counter electrode component and photoelectrode component were coated on each side of the single mesh. The fabricated single mesh DSSCs showed the energy-conversion efficiency 0.50% which show highly bendable ability. The new single mesh DSSCs may have potential applications as highly bendable solar cells to overcome the limitations of TCO-based DSSCs.

• Structural Engineering and Mechanics
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• v.55 no.1
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• pp.229-244
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• 2015

H-infinity norm relates to the maximum in the frequency response function and H-infinity control method focuses on the case that the vibration is excited at the fundamental frequency, while 2-norm relates to the output energy of systems with the input of pulses or white noises and 2-norm control method weighs the overall vibration performance of systems. The trade-off between the performance in frequency-domain and that in time-domain may be achieved by integrating two indices in the mixed vibration control method. Based on the linear fractional state space representation in the modal space for a piezoelectric flexible structure with uncertain modal parameters and un-modeled residual high-frequency modes, a mixed dynamic output feedback control design method is proposed to suppress the structural vibration. Using the linear matrix inequality (LMI) technique, the initial populations are generated by the designing of robust control laws with different H-infinity performance indices before the robust 2-norm performance index of the closed-loop system is included in the fitness function of optimization. A flexible beam structure with a piezoelectric sensor and a piezoelectric actuator are used as the subject for numerical studies. Compared with the velocity feedback control method, the numerical simulation results show the effectiveness of the proposed method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.473-476
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• 2003

This paper shows necessity of encapsulation layer to maximite flexibility of brittle indium-tin-oxide (ITO) on polymer substrates. And, Young's modulus (E) of encapsulation layer have an significant effect on external bending stress and the coefficient of thermal expansion (CTE) of that have a significant effect on internal thermal stress. To compare magnitude of total mechanical stress including both bending stress and thermal stress, the mechanical stress of triple-layer structure (substrate / ITO / encapsulation layer or substrate / buffer layer / ITO) can be quantified and numerically analyzed through the farthest cracked island position. As a result, it should be noted that multi-layer structures with more elastic encapsulation material have small mechanical stress compared to that of buffer and encapsulation structure of large Young's modulus material when they were externally bent.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.3
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• pp.233-243
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• 2017

This paper proposes a structure of direct-printed flexible tactile-sensor. These flexible tactile sensors are based on pressure-sensing materials that allow pressure to be measured according to resistance change that in turn results from changes in material size because of compressive force. The sensing material consists of a mixture of multi walled carbon nanotubes (MWCNTs) and TangoPlus, which gives it flexibility and elasticity. The tactile sensors used in this study were designed in the form of array structures composed of many lines so that single pressure points can be measured. To evaluate the performance of the flexible tactile sensor, we used specially designed signal-processing electronics and tactile sensors to experimentally verify the sensors' linearity. To test object grasp, tactile sensors were attached to the surface of the fingers of grippers with three degrees of freedom to measure the pressure changes that occur during object grasp. The results of these experiments indicate that the flexible tactile sensor-based robotic gripper can grasp objects and hold them in a stable manner.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.7
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• pp.687-694
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• 2006

We report on the fabrication of organic-based flexible displays using an amorphous IZO anode grown at room temperature. The IZO anode films were grown by a conventional DC reactive sputtering on the polycarbonate (PC) substrate at room temperature using a synthesized IZO target in a $Ar/O_2$ ambient. Both x-ray diffraction (XRD) and high resolution electron microscope (HREM) examination results show that the IZO anode film grown at room temperature Is complete amorphous structure due to low substrate temperature. A sheet resistance of $35.6\Omega/\Box$, average transmittance above 90 % in visible range, and root mean spare roughness of $6\sim10.5\AA$ were obtained even in the IZO anode film grown on PC substrate at room temperature. It is shown that the $Ir(ppy)_3$ doped flexible organic light emitting diode (OLED) fabricated on the IZO anode exhibit comparable current-voltage-luminance characteristics as well as external quantum efficiency and power efficiency to OLED fabricated on conventional ITO/Glass substrate. These findings indicate that the IZO anode film grown on PC substrate is a promising anode materials for the fabrication of organic based flexible displays.

• Structural Engineering and Mechanics
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• v.59 no.4
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• pp.739-759
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• 2016

The failure of civil engineering systems is a consequence of decision making under uncertain conditions. Generally, buried flexible pipes are designed for their transversal behavior to prevent from the important failure mode of buckling. However, the interaction effects between soil and pipe are neglected and the uncertainties in their properties are usually not considered in pipe design. In this regard, the present research paper evaluates the effects of these uncertainties on the uncertainty of the critical buckling hoop force of flexible pipes shallowly buried using the subgrade reaction theory (Winkler model) and First-Order Second-Moment (FOSM) method. The results show that the structural uncertainties of the studied pipes and those of the soil properties have a significant effect on the uncertainty of the critical buckling hoop force, and therefore taking into account these latter in the design of the shallowly flexible pipes for their buckling behavior is required.