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Adaptive Compensation Method for the Temperature Dependence of RF Transformer Isolation
Aoyama, Takanobu,Shibata, Yoshiki,Kanie, Tomohiko,Noro, Yuichi,Takeo, Takashi The Korean Institute of Electrical Engineers 2012 The Journal of International Council on Electrical Vol.2 No.4
In this study, we propose an adaptive compensation method for the temperature dependence of RF transformer isolation and present results of preliminary experiments. First of all, we examine the isolation temperature dependence of an RF transformer designed as a splitter, by means of both an electromagnetic simulation technique and experiments, to show the significance of the present issue. Then, we discuss the nature of a transformer core so as to obtain the most desirable isolation characteristics against a temperature change. Finally, in order to adaptively compensate for the isolation variation due to temperature, we propose a bias current superimposed on the RF signal, where the current amplitude is adjusted according to temperature change, and demonstrate the results of preliminary experiments conducted at a fixed temperature, but with different bias currents, indicating the validity of the proposed method.
헬리콥터의 고속충격소음 감소를 위한 블레이드 평면형상 최적화
채상현(Sanghyun Chae),양충모(Chooongmo Yang),정신규(Shinkyu Jung),Takashi Aoyama,Shigeru Obayashi,이관중(Kwanjung Yee) 한국전산유체공학회 2009 한국전산유체공학회지 Vol.14 No.1
The objective of this research is to design blade planform to reduce high speed impulsive(HSI) noise from a non-lifting helicopter rotor using CFD method and optimization techniques. As for the aero-acoustic analysis. CFD technique for aerodynamic analysis and Kirchhoff's method for the acoustic analysis were used. As for the optimization method, Kriging-based genetic algorithm(GA) model as a high-fidelity optimization method was chosen. Design variables and constraints are determined for arbitrary blade planform. The result shows that the optimized blade platform with high swept-back and taper ratio can reduce HSI noise by suppressing generation of the strong shock wave on blade surface and propagation of the noise to the farfield flow region.