Effect of the Annealing Conditions on the Ferromagnetic Resonance of YIG Thin Film Prepared on GGG Substrate (original) (raw)
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Annealing Characteristics of Electrodeposited Cu(In,Ga)Se2 Photovoltaic Thin Films
Korean Journal of Materials Research, 2010
Cu(In,Ga)Se 2 (CIGS) photovoltaic thin films were electrodeposited on Mo/glass substrates with an aqueous solution containing 2 mM CuCl 2 , 8 mM InCl 3 , 20 mM GaCl 3 and 8 mM H 2 SeO 3 at the electrodeposition potential of −0.6 to −1.0 V(SCE) and pH of 1.8. The best chemical composition of Cu 1.05 In 0.8 Ga 0.13 Se 2 was found to be achieved at −0.7 V(SCE). The precursor Cu-In-Ga-Se films were annealed for crystallization to chalcopyrite structure at temperatures of 100-500 o C under Ar gas atmosphere. The chemical compositions, microstructures, surface morphologies, and crystallographic structures of the annealed films were analyzed by EPMA, FE-SEM, AFM, and XRD, respectively. The precursor Cu-In-Ga-Se grains were grown sparsely on the Mo-back contact and also had very rough surfaces. However, after annealing treatment beginning at 200 o C, the empty spaces between grains were removed and the grains showed well developed columnar shapes with smooth surfaces. The precursor Cu-In-Ga-Se films were also annealed at the temperature of 500 o C for 60 min under Se gas atmosphere to suppress the Se volatilization. The Se amount on the CIGS film after selenization annealing increased above the Se amount of the electrodeposited state and the MoSe 2 phase occurred, resulting from the diffusion of Se through the CIGS film and interaction with Mo back electrode. However, the selenization-annealed films showed higher crystallinity values than did the films annealed under Ar atmosphere with a chemical composition closer to that of the electrodeposited state.
Korean Journal of Materials Research, 2019
The recent development of information and communication technologies brings new changes to automobile traffic systems. The most typical example is the advancement of dedicated short range communication(DSRC). DSRC mainly consists of an intelligent transportation system(ITS), an electronic toll collection system(ETCS) and an advanced traveler information system(ATIS). These wireless communications often cause unnecessary electromagnetic waves, and these electromagnetic waves, in turn, cause frequent system malfunction. To solve this problem, an absorber of electromagnetic waves is suggested. In this research, various materials, such as powdered metal and iron oxides, are used to test the possibility for an effective absorption of the unnecessary electromagnetic waves. The various metal powders are made into a thin sheet form by compositing through processing. The electromagnetic characteristics(complex permittivity, complex permeability) of the fabricated sheet are measured. As a res...
Journal of Korean Society For Rock Mechanics, 2013
While geothermal energy provides the only base-load power among renewable energy sources, its development has been carried out predominantly in volcanic area. EGS (Enhanced Geothermal System) is a ubiquitous technology that can allow the geothermal power generation virtually in any area. This manuscript introduces the current state-of-the-art of EGS development in the world and presents the hydraulic stimulation technology and associated microseismicity which are key technical component in EGS. Finally this paper suggests the key research areas required in Korea for further development of EGS.
고인성 섬유보강 무시멘트 복합체의 기초 배합 및 역학 실험
Journal of the Korea Concrete Institute, 2012
Cement has been traditionally used as a main binding material of high ductile fiber reinforced cementitious composites. The purpose of this paper is to investigate the feasibility of using alkali-activated slag and polyvinyl alcohol (PVA) fibers for manufacturing high ductile fiber reinforced cementless composites. Two mixture proportions with proper flowability and mortar viscosity for easy fiber mixing and uniform fiber dispersion were selected based on alkali activators. Then, the slump flow, compression, uniaxial tension and bending tests were performed on the mixes to evaluate the basic properties of the composites. The cementless composites showed an average slump flow of 465 mm and tensile strain capacity of approximately 2% of due to formation of multiple micro-cracks. Test results demonstrated a feasibility of manufacturing high ductile fiber reinforced composites without using cement.
Journal of the Korean Ceramic Society, 2014
Air-cooled slag showed grindability approximately twice as good as that of water-cooled slag. While the studied water-cooled slag was composed of glass as constituent mineral, the air-cooled slag was mainly composed of melilite. It is assumed that the sulfur in air-cooled slag is mainly in the form of CaS, which is oxidized into CaS 2 O 3 when in contact with air. CaS 2 O 3 , then, is released mainly as S 2 O 3 2ion when in contact with water. However, the sulfur in water-cooled slag functioned as a constituent of the glass structure, so the S 2 O 3 2− ion was not released even when in contact with water. When no chemical admixture was added, the blended cement of aircooled slag showed higher fluidity and retention effect than those of the blended cement of the water-cooled slag. It seems that these discrepancies are caused by the initial hydration inhibition effect of cement by the S 2 O 3 2ion of air-cooled slag. When a superplasticizer is added, the air-cooled slag used more superplasticizer than did the blast furnace slag for the same flow because the air-cooled slag had higher specific surface area due to the presence of micro-pores. Meanwhile, the blended cement of the air-cooled slag showed a greater fluidity retention effect than that of the blended cement of the water-cooled slag. This may be a combined effect of the increased use of superplasticizer and the presence of released S 2 O 3 2ion; however, further, more detailed studies will need to be conducted.
KEPCO Journal on electric power and energy, 2015
Large scale superconducting magnetic energy storage (SMES) system requires very high magnetic energy density in its superconducting coils to enhance the energy capacity and efficiency of the system. The recent high temperature superconducting (HTS) conductors, so called 2G conductors, show very good performance under very high magnetic field so that they seem to be perfect materials for the large scale SMES coils. A general shape of the coil system with the 2G HTS conductor has been a toroid, because the magnetic field applied perpendicularly to the surface of the 2G HTS conductor could be minimized in this shape of coil. However, a toroid coil requires a 3-dimensional computation to acquire the characteristics of its critical current densitymagnetic field relations which needs very complicated numerical calculation, very high computer specification, and long calculation time. In this paper, we suggested an analytic and statistical calculation method to acquire the maximum magnetic flux density applied perpendicularly to the surface of the 2G HTS conductor and the stored energy in the toroid coil system. Although the result with this method includes some errors but we could reduce these errors within 5 percent to get a reasonable estimation of the important parameters for design process of the HTS toroid coil system. As a result, the calculation time by the suggested method could be reduced to 0.1 percent of that by the 3-dimensional numerical calculation.
적층복합재료 패널의 확률론적 비선형 초기파단하중 및 좌굴하중에 관한 연구
Journal of the Korea institute for structural maintenance and inspection, 2013
Probabilistic nonlinear first ply failure loads of flat composite panels and nonlinear buckling loads of curved composite panels with cutouts are estimated to provide the more reliable main load carrying structure in the renewable energy industry and offshore structures. The response surface method approximates limit state surface to a second order polynomial form of random variables with the results of deterministic finite element analyses at given sampling design points. Furthermore, the iterative linear interpolation scheme is used to obtain a more accurate approximation of the limit state surface near the most probable failure point (MPFP). The advanced first order second moment method and the Monte Carlo method are performed on an approximated limit state surface to evaluate the probability of failure. Finally, the sensitivity of the reliability index with respect to transformed random variables is investigated to figure out the main random variables that have an effect on failures.
Effects of 3D Topography on Magnetotelluric Responses
2007
For precise interpretation of magnetotelluric (MT) data distorted by irregular surface terrain, topography effects are investigated by computing apparent resistivities, phases, tippers and induction vectors for a three-dimensional (3D) hill-and-valley model. To compute MT responses for the 3D surface topography model, we use a 3D MT modeling algorithm based on an edge finite-element method which is free from vector parasites. Distortions on the apparent resistivity and phase are mainly caused by distorted currents that flow along surface topography. The distribution of tipper amplitudes over both hill and valley are the same, while the tipper points toward the center of hill and the base of the valley. The real part of induction vector also points in the same direction as that of tipper, while the imaginary part in the opposite direction.