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문수덕,박재일,최경,황희용 강원대학교 정보통신연구소 2005 정보통신논문지 Vol.9 No.-
In this paper, A ultra wideband antenna with electromagnetically coupled feeding is presented. The designed antenna is composed of Bow-tie patch with parasitic patch ground of a semicircular shape. The measured bandwidth of the designed antenna is from 2.5GHz to 8.3GHz for -10dB return loss (VSWR < 2). This antenna shows a similar radiation pattern of monopole and maximum gain better than ideal dipole throughout the operating frequency band.
문수덕,김진규,황희용 강원대학교 산업기술연구소 2007 産業技術硏究 Vol.27 No.A
In High-Speed DSP systems, crosstalk between transmission lines of multi-channel can degrade the performance of equipment operations, This paper presents a microwave board to measure multi-channel coaxial cable assembly. The designed board has good performances from DC to 3 GHz, which have improved characteristic impedance, reduced crosstalk by using via fence, and low transmission loss. Using the designed board, we can measure characteristics of DUT(Device Under Test) such as return loss, insertion loss, crosstalk, phase delay, and characteristic impedance. The measured results are used to improve performances of a produced coaxial cable assembly.
The Vertical Fluxes of Particles and Radionuclides in the East Sea
Moon, Deok-Soo,Kim, Kee-Hyun,Noh, Il The Korean Society of Oceanography 2000 Journal of the Korean Society of Oceanography Vol.35 No.1
In order to measure the vertical fluxes of particles and reactive radionuclides such as thorium and polonium isotopes, Dunbar-type sediment traps were freely deployed at the Ulleung Basin and in warm and cold water masses around the polar front of the East Sea. We estimated the ratios of the catched (F) to the predicted $^234$Th fluxes (P) using natural tracers pair $^234$Th-$^238$U. The F/P ratios are decreased with increasing water depth. Whereas the concentrations of suspended particles are homogeneous in water column, the mass fluxes are also decreased with increasing water depth like the F/P ratios. These facts indicate that organic matters of settling particles are destructed within the euphotic layer due to decomposition. Whereas regenerations of sinking particles are negligible in the cold water mass, about 80% of them are regenerated in the warm water mass during falling of large particles. These downward mass fluxes are closely correlated with their primary productions in euphotic zone. The activities of $^234$Th, $^228$Th and $^210$Po in the sinking material were increased with water depth. Because $^234$Th steadily produced in the water column are cumulatively adsorbed on the surface of sinking particles, vertical $^234$Th fluxes were observed to increase with water depth. Therefore, these sinking particles play important roles in transporting the particle reactive elements like thorium from surface to the deep sea. The scavenging processes including adsorption and settling reactions generate radio-disequilibrium between daughter and parent nuclides in water column. The activity ratios of $^234$Th/$^238$U and $^228$Th/$^228$Ra were observed to be < 1.0 in the surface water and approached to be equilibrium below the thermocline. The extent of the deficiency of daughter nuclides compared to the parents nuclide was highly correlated with the vertical particle flux. Because most of the $^210$Po in the surface water are scavenged on a labile phase and are recycled at sub-surface depths (< 200 m), the $^210$Po are always observed to be excess activities compared to $^226$Ra in surface water.