Recently, the rapid advancement of the IT industry has resulted in significant changes in audio-system configurations; particularly, the audio over internet protocol (AoIP) network-based audio-transmission technology has received favourable evaluations in this field. Applying the AoIP in a certain section of the multiple-cable zone is advantageous because the installation cost is lower than that for the existing systems, and the original sound is transmitted without any distortion. The existing AoIP-based technology, however, cannot control the audio-signal characteristics of every device and can only transmit multiple audio signals through a network. In this paper, the proposed Audio Network & Control Hierarchy Over peer-to-peer (Anchor) system enables all audio equipment to send and receive signals via a data network, and the receiving device can mix the signals of different IPs. Accordingly, it was possible to improve the system-application flexibility by simplifying the audio-system configuration. The research results confirmed that the received audio signals from different IPs were received, mixed, and output without errors. It is expected that Anchor will become a standard for audio-network protocols.
The magnetic properties of the U-type ferrite synthesized by a sol-gel process had studied by substituting cobalt with manganese or zinc in cobalt-based U-type ferrite. The substituted U-type ferrite showed a dominant crystal structure at a different substitution ratio of manganese and zinc. The change of the starting temperature of U-type ferrite formation according to substitutional elements was confirmed by TG-DTA analysis. In the case of manganese substitution, the starting temperature of U-type ferrite formation lowered, and on the contrary, when zinc was substituted, it became higher. The magnetic properties of the U-type ferrite substituted with manganese showed a tendency that the saturation magnetization was decreased and the coercivity was increased as the manganese ratio increased. The highest saturation magnetization was 57.9 emu/g in the specific composition (Ba4Co0.5Zn1.5Fe36O60) substituted with zinc.
We fabricated two different kinds of composite materials for absorbing microwave in a frequency range of 2 to 18 GHz using coaxial airline and thru-reflect-line (TRL) method. The composite materials having carbon nanotube (CNT) with carbonyl iron (CI) or iron oxide (Fe3O4) were fabricated by mixing each components. Magnetic properties were measured by SQUID equipment. Complex permittivity and complex permeability were also obtained by measuring S-parameters of the toroidal specimen dispersing CI/CNT and Fe3O4/CNT into the 50 weight percent (wt%) epoxy resin. The real permittivity was improved by mixing the CNT however, the real permeability was same as pure magnetic powders. The CI/CNT had a maximum value of real permittivity and real permeability, 11 and 1.4 at 10 GHz, respectively. The CNT composites can be adapted to the radar absorbing materials, band width 8-12 GHz.