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71.
Myoung-hun Han Bong-Soo Roh Kyungwoo Kim Dae-Hoon Kwon Jae-Hyun Ham KyungHyun Yoon Sanghyun Seo 《计算机、材料和连续体(英文)》2022,70(2):2381-2399
An important requirement in a military domain is a highly reliable mobility management method, especially when components of the networks are moving in tactical network environments. To increase reliability, the mobility management technology of the tactical network should be able to reflect the characteristics of the tactical network, such as a limited environment, failure, and hierarchical unit structure. In this paper, we propose a proxy-based hierarchical distributed mobility management scheme, which is highly focused on tactical networks. Considering the characteristics of tactical networks, the proposed scheme is composed of the following: 1) a proxy-based method, 2) a distributed mobility management method that synchronizes a mobility database between entities, and 3) a method of managing mobility by dividing the tactical network into upper and lower layers. Mathematical analysis and modeling and simulation results demonstrate that the method outperforms the existing state-of-the-art method in overcoming entity failure, handover cost, and delay in tactical environments. 相似文献
72.
Woo-Suk Seo Soon-Young Yang Byung-Ryong Lee Kyoung-Kwan Ahn Young-Bog Ham 《Journal of Mechanical Science and Technology》2007,21(8):1320-1327
This paper presents the design, fabrication, and experimental investigation of a novel planar pump using electro-conjugate
fluid. The electro-conjugate fluid (ECF) is a kind of dielectric functional fluid which generates a powerful jet flow (ECF-jet)
when a static electric field is applied via a pair of rod-like electrodes. This phenomenon that ECF can generate jet flows
from the positive electrode to the ground electrode in an applied electric field is called the ECF effect, and converts electric
energy directly into kinetic energy of the fluid. The ECF-jet acts directly on the working fluids; therefore, the proposed
planar ECF pump requires no moving parts and produces no vibration or noise. The fabricated planar ECF pump consists of three
parts: a pump base, a top cover, and an electrode substrate with dimensions of 280 mm × 190 mm × 1 mm. In this paper, five
different electrode patterns and three different flow channel heights were investigated for the realization of a high-performance
planar ECF pump. Each array of electrodes was patterned on the glass epoxy substrates using a wet-etching process, and the
flow channel heights were either 200 μm, 300 μm, or 500 μm. The pumping experiments used FF-1EHA2 as the working fluid. Experimentation showed that a no-load flow rate of 5.5 cm3/s, maximum output pressure of 7.2 kPa, and maximum output power of 11.6 mW were achieved at an applied voltage of 2.0 kV. 相似文献
73.
D.S. Popplewell G.J. Ham T.E. Johnson J.W. Stather S.A. Sumner 《The Science of the total environment》1984
Transfer factors have been measured for 239Pu + 240Pu, 241Am, 90Sr and 137Cs into potatoes grown in a blend of soil which included silt polluted with radioactive waste discharged into the Irish Sea. The experiment has been carried out over four seasons and attempts to assess the radiological consequences to the consumer which would arise if potatoes were to be grown in land heavily contaminated with the silt. During the course of the experiment plutonium and americium became less available for uptake, 90Sr became slightly more available and 137Cs remained nearly constant in its availability. The values of the transfer factors are among the lowest reported for these radionuclides into potatoes. 相似文献
74.
Residents and non-residents are likely to think differently about a neighbourhood's reputation. Relatively little is known about the similarities and differences between these internal and external types of neighbourhood reputation or the relationship between reputations and ‘real’ or ‘objective’ neighbourhood characteristics. This paper addresses two points: first, the extent to which neighbourhood reputations differ between and within groups; second, the extent to which these neighbourhood reputations are associated with measured neighbourhood characteristics. Data from a specially designed survey carried out in 24 neighbourhoods in Utrecht, the fourth largest city in the Netherlands, are used. Analysis of the data showed that neighbourhood reputations are rated higher by residents and estate agents than by other city residents. Within the group of other city residents, differences were found in how neighbourhood reputations are rated by socio-economic status, ethnicity and educational background. Further, it was found that neighbourhood reputations are correlated with measured social characteristics of the neighbourhood, while physical and functional neighbourhood characteristics are of less importance. 相似文献
75.
Chang-Whan Lee Byeong Wan Kwon Min-Goo Kang Hyung-Chul Ham Sung-Pil Yoon Jonghee Han Young Jin Kim Min Chul Lee 《International Journal of Hydrogen Energy》2017,42(29):18514-18523
In order to improve the stack life time of MCFCs, it is necessary to reduce the operating temperature of MCFCs below 600 °C, because reduced operating temperature minimizes electrolyte loss due to evaporation and corrosion. However, at the low operating temperature below 600 °C, the cell performance of MCFCs with (Li/Na)2CO3 electrolyte is too low to operate the fuel cell stack and system. In this study, we have performed wettability control of the liquid molten carbonate electrolyte by coating NiO cathodes with poor wetting property of the mixed ionic and electronic conductor (MIEC) such as BYS (Bi1.5Y0.3Sm0.3O3-δ). From experiments with symmetrical cells, each polarization component with various temperatures and gas conditions were studied. To investigate effects of the BYS coated cathode on the performance of MCFCs, a 100 cm2 single cell of MCFCs was employed. The performance of a 100 cm2 single cell with BYS coated cathode was better than that with conventional cathode by a factor of 1.84, because BYS coated cathode reduces activation polarization and mass transfer resistance greatly. 相似文献
76.
Yong Ju Ham Jun Kue Park W. Lee Cheol Eui Lee W. Park 《Materials Research Bulletin》2012,47(9):2403-2406
Optical properties of proton-implanted ZnO thin film prepared by radio-frequency (rf) magneton sputtering have been studied, the optical constants being obtained from the reflectance measurements by employing Cauchy–Urbach model. Increase in the ordinary refractive index after proton implantation was explained by that in the polarizability. Besides, a slight increase in the optical band gap by proton implantation was identified and discussed in terms of the hydrogen shallow donors introduced by the proton implantation. 相似文献
77.
Due to their simple geometry and design, planar heterojunction (PHJ) solar cells have advantages both as potential photovoltaics with more efficient charge extraction than their bulk heterojunction (BHJ) counterparts, and as idealized interfaces to study basic device operation. The main reason for creating BHJs was the limited exciton diffusion length in the active materials of the PHJ: if an exciton is generated at a distance greater than its diffusion length from the hetero-interface of the PHJ, it would be very unlikely to be able to contribute to the photocurrent. Based on this argument one expects a maximum in the photocurrent of PHJs for a thickness of the active layer equal to the exciton diffusion length (~10 nm). However, in two recently developed PHJs that have appeared in the literature, a maximum photocurrent is observed for 60-65 nm of poly(3-hexylthiophene) (P3HT). In this work, we explore this anomaly by combining both an optical T-matrix and a kinetic Monte Carlo simulation that tracks the exciton behavior in the PHJs. The two systems considered are a P3HT/single walled carbon nanotube (SWNT) device, and a P3HT/phenyl-C61-butyric acid methyl ester (PCBM) device. The model demonstrates how a bulk exciton sink can explain the shifted maximum in the P3HT/SWNT case, whereas in the P3HT/PCBM case the maximum is mainly determined by PCBM molecules interdiffusing in the P3HT upon annealing. Based upon the results of this model it will be possible to more intelligently design nanostructured photovoltaics and optimize them toward higher efficiencies. 相似文献
78.
Ham YH Kim DP Baek KH Park KS Kim M Kwon KH Shin HS Lee K Do LM 《Journal of nanoscience and nanotechnology》2012,12(7):5897-5901
We demonstrated the feasibility of metal and dielectric liners using a solution process for deep trench capacitor application. The deep Si trench via with size of 10.3 microm and depth of 71 microm were fabricated by Bosch process in deep reactive ion etch (DRIE) system. The aspect ratio was about 7. Then, nano-Ag ink and poly(4-vinylphenol) (PVPh) were used to form metal and dielectric liners, respectively. The thicknesses of the Ag and PVPh liners were about 144 and 830 nm, respectively. When the curing temperature of Ag film increased from 120 to 150 degrees C, the sheet resistance decreased rapidly from 2.47 to 0.72 Omega/sq and then slightly decreased to 0.6 Omega/sq with further increasing the curing temperature beyond 150 degrees C. The proposed liner formation method using solution process is a simple and cost effective process for the high capacity of deep trench capacitor. 相似文献
79.
Kim M Lee SK Ham YH Yang YS Kwon JK Kwon KH 《Journal of nanoscience and nanotechnology》2012,12(8):6283-6286
We designed and fabricated a bimorph cantilever array for sustainable power with an integrated Cu proof mass to obtain additional power and current. We fabricated a cantilever system using single-crystal piezoelectric material and compared the calculations for single and arrayed cantilevers to those obtained experimentally. The vibration energy harvester had resonant frequencies of 60.4 and 63.2 Hz for short and open circuits, respectively. The damping ratio and quality factor of the cantilever device were 0.012 and 41.66, respectively. The resonant frequency at maximum average power was 60.8 Hz. The current and highest average power of the harvester array were found to be 0.728 mA and 1.61 mW, respectively. The sustainable maximum power was obtained after slightly shifting the short-circuit frequency. In order to improve the current and power using an array of cantilevers, we also performed energy conversion experiments. 相似文献
80.
In the paper, we describe new Ir complexes for achieving efficient blue phosphorescence. New blue-emitting mixed-ligand Ir complexes comprising one cyclometalating, two phosphines trans to each other such as Ir(dppz)(PPh3)2(H)(L) (Ll= Cl, NCMe+, CN), [dppz = 3,5-Diphenylpyrazole] were synthesized and studied to tune the phosphorescence wavelength to the deep blue region and to enhance the luminescence efficiencies. To gain insight into the factors responsible for the emission color change and the variation of luminescence efficiency, we investigate the electron-withdrawing capabilities of ancillary ligands using DFT and TD-DFT calculations on the ground and excited states of the complexes. To achieve deep blue emission and increase the emission efficiency, (1) we substitute the phenyl group on the 3-position of the pyrazole ring that lowers the triplet energy enough that the quenching channel is not thermally accessible and (2) change the ancillary ligands coordinated to iridium atom to phosphine and cyano groups known as very strong field ligands. Their inclusion in the coordination sphere can increase the HOMO-LUMO gap to achieve the hypsochromic shift in emission color and lower the HOMO and LUMO energy level, which causes a large d-orbital energy splitting and avoids the quenching effect to improve the luminescence efficiency. The maximum emission spectra of Ir(dppz)(PPh3)2(H)(CI) and Ir(dppz)(PPh3)2(H)(CN) were in the ranges of 439, 432 nm, respectively. 相似文献