• 한국전산유체공학회지
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• 제12권1호
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• pp.1-8
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• 2007

A code is developed using the hybrid Cartesian/immersed boundary method and it is applied to simulate flows around a three-dimensional deforming body. A new criterion is suggested to distribute the immersed boundary nodes based on edges crossing a body boundary. Velocities are reconstructed at the immersed boundary nodes using the interpolation along a local normal line to the boundary. Reconstruction of the pressure at the immersed boundary node is avoided using the hybrid staggered/non-staggered grid method. The developed code is validated through comparisons with other experimental and numerical results for the velocity profiles around a circular cylinder under the forced in-line oscillation and the pressure coefficient distribution on a sphere. The code is applied to simulate the flow fields around a plate whose tail is periodically flapping under a translation. The effects of the velocity and acceleration due to the deformation on the periodic shedding of pairs of tip vortices are investigated.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.335.1-335.1
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• 2016

The electronic structures of a hybrid magnetic-electric quantum ring and two terminal conductance taking into account the resonant backscattering via both magnetic and electric edge channels are studied. The hybrid magnetic-electric quantum ring is formed by a magnetic quantum dot combined with an additional antidot electrostatic potential at the center of the dot. Electrons are both magnetically and electrically confined to the plane. The antidot potential repelling electrons from the center of the dot plays an important role in the energy spectra and magnetoconductance. The angular momentum transition in the ground state and the behavior of magnetoconductance due to a change of the antidot potential are shown in comparison with the conventional magnetic quantum dot.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.703-707
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• 2001

A performance analysis of a SOFC/MGT hybrid system has been carried out for concept design. Thermo-dynamic models for each component being able to describe electrochemical characteristics and heat and mate-rial balance are proposed. Estimated is the power capacity of a SOFC suitable for the hybrid operation with a 5kW class MGT. Effects of current density and operating pressure are also investigated. Electric efficiency showed weak dependence on operating pressure and current density. It is desirable that the SOFC operates at high current density in manufacturing cost's point of view though operating with high current density slightly decreases the electric efficiency find specific power.

• 전기학회논문지P
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• 제52권1호
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• pp.14-19
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• 2003

The effect of the Pt electrode and the $Pt-IrO_2$ hybrid electrode on the performance of ferroelectric device was investigated. The modified Pt thin films with non-columnar structure significantly reduced the oxidation of TiN diffusion barrier layer, which rendered it possible to incorporate the simple stacked structure of Pt/TiN/poly-Si plug. When a $Pt-IrO_2$ hybrid electrode is applied, PZT thin film properties are influenced by the thickness and the partial coverage of the electrode layers. The optimized $Pt-IrO_2$ hybrid electrode significantly enhanced the fatigue properties of the PZT thin film with minimal leakage current.

• 한국소음진동공학회논문집
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• 제22권12호
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• pp.1157-1163
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• 2012

Natural frequency of a nano-resonator via nano transfer printing is studied. Through a nano transfer printing, the hybrid metal/polymer membrane may evolve a wrinkle. Natural frequency of a wrinkled hybrid membrane decreases significantly, as the amplitude to wavelength ratio becomes larger. To address the design limit of a hybrid nano resonator, we perform parametric study using finite element analysis. Specifically, we study the effects of the Young's modulus ratio of the metal/polymer membrane, thickness ratio and wrinkle amplitude to wavelength ratio, respectively. The results from the parametric studies can serve as guideline to design hybrid nano resonators.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.780-787
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• 2017

The propellant grain configuration is a design variable that determines the shape and performance of a solid rocket motor. Grain configuration variables have complicated effects on the motor performance; so the global optimization problem has to be solved in order to design the configuration variables. The grain performance has been analyzed by means of the grain burn-back and internal ballistic analysis, and the optimization technique searches for the configuration variables that satisfy the requirements. The deterministic and stochastic optimization techniques have been applied for the grain optimization, but the results are imperfect. In this study, the optimization design of the configuration variables has been performed using the hybrid optimization technique, which combines those two techniques. As a result, the hybrid optimization technique has proved to be efficient for the grain optimization design.

• 한국태양에너지학회 논문집
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• 제25권3호
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• pp.47-52
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• 2005

Normally if sunlight is directed on a solar cell without any increasing in temperature, the amount of absorption energy per unit area of each cell is increasing. In a silicon solar cell. however, cell conversion efficiency decreases with the increase of temperature. Therefore, to maintain cell conversion efficiency under normal condition, it is necessary to keep the cell at operating temperature. We tried to design and make new hybrid panel with cooling system to prevent increasing of temperature on cell, collect and use thermal energy more effectively. We compared performance of this new hybrid panel with current thermal panel. We also evaluated conversion efficiency, thermal capacity and confirmed cooling effects from thermal absorption efficiency.

• Macromolecular Research
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• 제11권3호
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• pp.172-177
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• 2003

Biphenyltetracarboximide-phenylene diamine polyimide/silica-titania ternary hybrid composites were Prepared by thermal imidization and sol-gel reaction. Fluorescence spectroscopic, scanning electron microscopy, and atomic force microscopy studies revealed that the addition of small amount of titania showed profound effects on the microstructure and photophysical behaviors of polyimide/silica hybrid composites, when the content of silica-titania mixture was small or when the ratio of silica to titania in the mixture was high.

• Macromolecular Research
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• 제8권3호
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• pp.120-124
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• 2000

Clay-dispersed nanocomposites have been prepared by simple melt-mixing of two components, styrenic polymers with different content of functional groups and two different organophilic clays (Cloisite(R) 25A and Cloisite(R)30A) with a twin screw extruder. Dispersibility of 10-$\AA$-thick silicate layers of clay in the hybrid was investigated by using an X-ray diffraction method and a transmission electron microscope. It was found that if the interaction force between intercalant and matrix polymer is attractive, the matrix polymer intercalates more rapidly into the gallery of silicate layers. The faster intercalation of matrix polymer leads to the better dispersibility of silicate layers in the matrix polymer.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.262-264
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• 2005

This paper is concerned with a fracture strength study of composite adhesive lap joints. The tests were carried out on specimen joints manufactured hybrid stacked joints such as the polyester and bamboo natural fiber layer. The main objective of the work was to test the fracture strength using hybrid fiber composites with a polyester and bamboo natural fiber layer adjacent to the spew fillet of adhesive bonded joints and hybrid stacked joints. The results are presented using tensile-shear strength graph and finite element analysis. The failure mechanisms are discussed in order to explain that spew fillet at the end of the overlap reduces greatly the adhesive shear and effects the tensile-shear strength in hybrid stacked joints.