Banach 공간에서의 약한 근사성질들

학위논문(박사) - 한국과학기술원 : 응용수학전공, 2007.2, [ iii, 81 p. ]This thesis is devoted to an investigation of various approximation properties in Banach spaces, relations between these properties, and various topologies on the space of operators. First, we introduce various weak approximation properties, which are in general weaker than known approximation properties, and establish necessary and sufficient conditions for Banach spaces to have those properties. And we study inheritances of those properties from the dual space of a Banach space to the Banach space and vice versa. Secondly, we study if one approximation property implies another. By providing elaborate examples we prove that some properties is strictly stronger than others. We also observe that for dual spaces or reflexive spaces more properties turn out to be equivalent. Finally, we consider various locally convex vector topologies on the space of bounded linear operators on Banach spaces and investigate their topological properties, including compactness. We then apply the results to our study of the approximation properties.한국과학기술원 : 응용수학전공

저 전압, 저 잡음, 저 전력 전압 제어 발진기 연구

학위논문(박사) - 한국과학기술원 : 전기및전자공학과, 2014.2, [ vii, 75 p. ]As CMOS technologies continue to be scaled down to reduce cost, increase speed, and achieve higher levels of integration, the analog/RF circuits are required to be designed with low supply voltage and low power. By the scaled supply voltage, however, the phase noise of the voltage-controlled oscillator (VCO), which is one of key blocks in the wireless system, is severely degraded due to the small output voltage swing. Moreover, the VCO is one of the blocks which have the high power consumption in the wireless transceiver. Therefore, the research for improving the phase noise and the power consumption is needed. In this thesis, for improving the phase noise and power consumption of VCO, we study the phase noise and the power consumption of both ring and LC VCO at the low supply voltage in deep-submicrometer technology. To solve the issues appeared in the study, three VCOs are proposed and explained. The proposed VCOs can be used as a low voltage, low noise, and low power VCO.한국과학기술원 : 전기및전자공학과

저 전압, 저 위상 잡음 링 전압 제어 발진기 설계

학위논문(석사) - 한국과학기술원 : 전기 및 전자공학과, 2010.2, [ vi, 56 p. ]This thesis presents a ring VCO for low phase noise and wide tuning range. Since the phase noise of the ring VCO is inherently poor, many have tried to improve the phase noise. However, the formally proposed ring VCOs have the problem of large noise or frequency tuning at low supply voltage. In order to solve the problems at the low supply, a ring VCO is proposed. The proposed ring VCO reduces the noise current and is applied to negative skewed delay. Therefore, the phase noise and frequency tuning are improved. For verification of the idea, the proposed ring VCO is compared with two conventional ring VCO at low supply voltage. The proposed ring VCO shows the better performances (phase noise, frequency tuning) than that of two conventional ring VCOs. The proposed ring VCO is implemented in 65nm CMOS technology. The supply voltage is 1V as a low voltage. The proposed ring VCO oscillates from 401.7MHz to 882.6MHz. At near 400MHz, the phase noise of the proposed ring VCO is -78.04 and -107.4 dBc/Hz at 100 KHz and 1 MHz offset frequency, respectively. The proposed ring VCO consumes 6.1~8.5mA from 1V supply.한국과학기술원 : 전기 및 전자공학과