• 한국전자통신학회논문지
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• 제8권9호
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• pp.1277-1283
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• 2013

본 논문에서는 마이크로스트립라인 종단형 CSRR구조를 이용하여 X-band 레이다에 사용하는 새로운 전압 제어 발진기를 제안하였다. 마이크로스트립 종단형 CSRR을 발진기와 버퍼 사이에 삽입되는 필터로 사용하여 고주파억압특성을 개선하였다. 측정 결과 제어전압을 0~10V로 가변 하였을 때 9.28~9.39GHz가 발진 하였으며 발진주파수 9.35GHz에서 16.6dBm의 높은 출력을 얻을 수 있었다. 또한 일반적인 발진기 보다 고주파억압 특성이 10.4dB 개선되었다.

• 산업기술연구
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• 제21권B호
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• pp.125-132
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• 2001

Heat dissipation technology using flow resonant phenomenon is a kind of new concept in heat transfer area. A vibration exciter is needed to generate air turbulence which has the natural shedding frequency of heat system. A mechanical vibrating device for the air flow oscillation is introduced, which is driven by a moving coil actuator. An analytical dynamic model for this mechanical vibration exciter is presented and its' validity is verified by the comparison with experimental data. Values of some unknown system parameters in the analytic model are estimated through the system identification approach. Based on this mathematical model, the vibration exciter using strain displacement estimator is developed. And in the experiment, the feedback control is used. During the experimental verification phase, it turns out the high modal resonant characteristics of vibrating plate are the major barrier against obtaining a high bandwidth vibration exciter.

• Journal of electromagnetic engineering and science
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• 제4권3호
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• pp.107-112
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• 2004

In this paper, the phase noise of 900 MHz VCO is improved using modified strip line square ring resonator. In order to demonstrate the phase noise improvement of the proposed VCO, the same circuit was manufactured using shorted-circuit resonator. In condition of the same bias current, the phase noise of the proposed VCO with modified square ring resonator is suppressed by 7 dB as - 103 dBc/Hz at 100 kHz offset compared to the conventional VCO with short-circuit resonator. From the proposed VCO, we achieved output power of - 4.8 dBm, harmonics suppression of 16 dB, and tuning bandwidth of 100 MHz. The proposed VCO consumed 5 mA at 3 V, and its size is 1.2 cm ${\times}$ 1.0 cm.

• 한국정밀공학회지
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• 제18권6호
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• pp.141-147
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• 2001

A heat dissipation technology using flow resonant phenomenon is a kind of new concept in heat transfer area. A vibration exciter is needed to generate an air turbulence which has the natural shedding frequency of a heat system. A mechanical vibrating device for the air flow oscillation is introduced, which is driven by a moving coil actuator. An analytical dynamic model for this mechanical vibration exciter is presented and its validity is verified by the comparison with experimental data. Values of some unko주 system parameters in the analytic model are estimated through the system identification approach. based on this mathematical model, a high bandwidth vibration exciter is designed using feedback control. During the experimental verification phased, it turns out the high frequency modal resonant characteristics of vibrating plate are the major barrier against obtaining a high bandwidth vibration exciter.

• 한국정보전자통신기술학회논문지
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• 제6권4호
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• pp.272-277
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• 2013

In this paper the effect of instability and chaos in optical fiber networks based on the Internet is described. Nonlinear optical fiber effect especially Brillouin scattering in networks has emerged as the essential means for the construction of active optical devices used for all-optic in-line switching, channel selection, amplification, oscillation in optical communications and a host of other applications. The inherent optical feedback by the back-scattered Stokes wave in optical networks also leads to instabilities in the form of optical chaos. This paradigm of optical chaos in fiber Internet serves as a test for fundamental study of chaos and its suppression and exploitation in practical application in optical fiber communication. This paper attempts to present a survey and some of our research findings on the nature of Brillouin chaotic effect on Internet based optical communication.

• 한국정보전자통신기술학회논문지
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• 제1권1호
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• pp.61-66
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• 2008

In this paper the effect of instability and chaos in optical fiber networks based on the Internet is described. Nonlinear optical fiber effect especially Brillouin scattering in networks has emerged as the essential means for the construction of active optical devices used for all-optic in-line switching, channel selection, amplification, oscillation in optical communications and a host of other applications. The inherent optical feedback by the back-scattered Stokes wave in optical networks also leads to instabilities in the form of optical chaos. This paradigm of optical chaos in fiber Internet serves as a test for fundamental study of chaos and its suppression and exploitation in practical application in optical fiber communication. This paper attempts to present a survey and some of our research findings on the nature of Brillouin chaotic effect on Internet based optical communication.

• 한국초전도ㆍ저온공학회논문지
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• 제2권1호
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• pp.24-30
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• 2000

This paper present the characteristics of the internal induced voltage and arc phenomena in liquid helium at the energy transfer from a superconducting magnet to a load resistor. Especially generation mechanism of the oscillated wave from of the coil terminal voltage is analyzed by considering circuit constant of the superconducting magnet, load condition and arc resistance of the mechanical opening switch. The wavefront and peak portion of the voltage are strongly influenced by arc discharge triggered by the switch separation in liquid helium. Abrupt arc extinction leads to voltage oscillation with an enormous peak. It is suggested that the superconducting magnet should be designed to ensure the internal surge when arc is possibly formed by switch opening or coil short circuit between turns or layers. Finally, a suppression method of the oscillating surge is proposed based on the load condition.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.177-181
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• 2002

In this paper, the cancellation or suppression of the feedback interference from Tx antenna using the same frequency is studied. The major problems on the wireless communication system using the same frequency or on-frequency repeater (OFR) are the coupling and isolation between Rx and Tx antenna. In order to increase the isolation between Rx and Tx antenna and to Prevent the self-oscillation of the receiver system, this paper is verified the possibility of the application of interference cancellation system and proposed the design method of the OFR using interference cancellation system.

• Journal of Mechanical Science and Technology
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• 제16권3호
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• pp.363-375
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• 2002

The effect of the electromagnetic force (or Lorentz force) on the flow behavior around a circular cylinder is investigated by computation. Two-dimensional unsteady flow computation for Re=10$^2$is carried out using a numerical method of finite difference approximation in a curvilinear body-fitted coordinate system by solving the momentum equations including the Lorentz force as a body force. The effect of spatial variations of the Lorentz forcing region and forcing direction along the cylinder circumference is investigated. The numerical results show that the Lorentz force can effectively suppress the flow separation and oscillation of the lift force of circular cylinder cross-flow, leading to reduction of drag.

• 대한전기학회논문지:전력기술부문A
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• 제50권11호
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• pp.497-505
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• 2001

The power system stabilizer(PSS) is important for the suppression of low-frequency oscillation and the improvement of system stability. In this paper, An Adaptive Neurofuzzy-based Power System Stabilizer(ANF PSS) is proposed as the new PSS type. The proposed PSS employs a multi-layer adaptive network. The network is trained directly from the input and the output of the generating unit. The algorithm combines the advantages of the Artificial Neural Network(ANN) and Fuzzy Logic Control(FLC) schemes. Studies show that the proposed ANF PSS can provide good damping of the power system over the wide range of operating conditions and improve the dynamic performance of the system.