• 한국전자파학회논문지
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• 제9권5호
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• pp.603-613
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• 1998

위스퍼링 갤러리 모드가 동작하는 유전체 원판 공진기의 공진 특성은 모드를 여기시키기 위하여 원판 공진기 주위에 배치한 외부 회로에 의하여 영향올 받게 된다. 이러한 현상올 해석하기 위하여, 원판 공진기를 모드 결합이 일어나는 결합부와 결합이 일어나지 않는 비결합부로 나누어 해석하였다. 결합부에서는 원판올 정합회로로 임피던스 매칭한 후, 비평형 유전체 도파로의 결합 전송 방정식을 유도하였다. 결합 전송 방정식으로부터 결합 계수, 결합 전자계 분포, 전력의 이동량 및 모드 결합 현상을 고려한 공진 주파수를 계산하였다. 또한, 공진 특성에 관한 실험을 통하여, 공진 주파수의 계산치와 실험치 간의 오차가 약 1.28%이고 FSR의 경우 약 0.6%임을 알 수 있었다.

• 소음진동
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• 제11권1호
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• pp.132-140
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• 2001

The vibratory gyroscope can effectively measure the angular velocity as the oscillating and position-sensing mode are exactly tuned. The veering Phenomenon impedes the exact tuning, which is caused by the mode coupling of two modes. In this paper, the gyroscope's structure with two frames is introduced to minimize the veering phenomenon that destabilizes the tuning process of oscillating and position-sensing mode. Experimental results show that the Proposed structure can achieve the mode intersection without veering phenomenon.

• 한국통신학회논문지
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• 제22권6호
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• pp.1251-1258
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• 1997

Generally, it is very important to study selective coupling between cavities of the filter structure using multimode cavity resonator. In this paper, we have manufactured 5-pole bandpass filter(BPF) using dual and triple-mode cavity resonator. To do so, we have derived the formulas for coupling coefficient about coupling between TE-modes from TM/TE-mode's tangential and lognitudinal field intensities each other. To implement the Chebyshev response, the intercabity slot combining dual-mode and triple-mode is designed to couple one H-field of TE-mode parallel to slot plate. In this paper, specially it is derived the formulas for T $E_{11p}$-mode from TE-modes, and determined after obtaining location and size of intercabity slot from the equation. In this ppaer, based on this result, we designed and implmented teh bandpass filter operated at the center frequency of 14.5GHz with a Chebyshev response. For the manufactured cavity filter, dual-mode and triple-mode cavity are resonted by two orthogonal T $E_{113}$-modes, and by two orthogonal T $E_{113}$-modes and one T $M_{012}$-mode, respecitively. The 2-stage 5-pole BPF proposed in this paper has the insertion loss of -2.32dB, the reflection loss of -15dB in the passband, and the out-or-rejection of -67dB.

• 융합신호처리학회논문지
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• 제13권4호
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• pp.201-206
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• 2012

간접접촉 심전도 측정(Indirect-Contact ECG)은 일상생활에서의 무구속 무자각 측정에 적합한 심전도 측정 방법이다. 본 연구는, 간접접촉 심전도 측정에서 크게 관측되는 60Hz 전원선 잡음을 줄이기 위한 새로운 방법으로, 공통모드 구동 차폐 방식을 제안하였다. 공통 모드 구동 차폐 방식은, 간접 접촉 심전도에서 사용되는 용량성 결합 능동 전극(Capacitive coupling active electrode)을 둘러싼 전기적 차폐(electric shield)의 전압을 공통 모드 전압과 동일하게 유지하는 방법이다. 이 방법은 공통모드 전압의 크기는 그대로 유지하지만, 의복 임피던스 차에 의한 공통모드 전압의 차동 모드 전환에 의한 잡음은 효과적으로 줄일 수 있다. 따라서 두 전극 사이의 의복의 임피던스 차이가 커서 공통 모드 전원 잡음이 심각한 간접 접촉 심전도 측정에서, 효과적으로 공통 모드 잡음을 줄일 수 있다. 실제 간접 접촉 심전도 측정에 제안된 방법을 적용한 결과로 이론적 예상보다는 60Hz 잡음 감소비가 적었지만, 60Hz 잡음이 크게 줄어드는 것을 확인할 수 있었다. 특히 의복 임피던스 차가 크게 발생하는 경우, 예상대로 잡음 감소비가 커짐을 볼 수 있었다. 제안된 방법은 접지 특성이 좋지 않은 측정 조건에서 전원 잡음을 줄이는데 유용할 것으로 기대된다.

• 한국전자파학회논문지
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• 제22권1호
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• pp.9-15
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• 2011

E 모양의 이중 모드 공진기를 변형하여 상.하측 대역의 대역폭 조절이 가능한 이중 대역 통과 필터를 설계 제작하였다. 변형된 E 모양의 이중 모드 공진기를 이용하여 even 모드 간의 결합이 odd 모드 공진점에 영향을 미치지 않게 만들었고, 이를 통하여 상측 대역의 대역폭을 효과적으로 조절할 수 있다. 그리고 급전 선로간의 결합을 통하여 차단 대역에 전송 영점을 발생시켜 차단 특성을 높였다. 대역폭 조절이 가능함을 보이기 위해 중심 주파수 2 GHz와 3 GHz에서 140 MHz의 동일한 대역폭을 갖는 필터를 설계하였다.

• International Journal of Precision Engineering and Manufacturing
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• 제8권2호
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• pp.32-37
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• 2007

This paper proposes a dual-mode ultra precision positioning system for machine tools and measuring machines. The objective was to position a machine table with a picometer order of resolution, i.e., pico-positioning. A twist-roller friction drive (TFD) was used in coarse-mode positioning. The TFD, which was driven by an AC servomotor, is a kind of lead screw in mechanical terms, and several centimeters of machine table movement was controlled with a nanometer order of positioning resolution. To eliminate lateral vibration caused by the TFD, an active aerostatic coupling driven by piezoelectric actuators was inserted between the TFD and the machine table. This active aerostatic coupling was also applied as a feed drive device for fine-mode positioning; in the fine mode, the positioning resolution was 50 pm. Factors influencing pico-positioning, such as how noise from displacement sensors and vibrations in the aerostatic guideway affect positioning resolution, are discussed.

• 한국소음진동공학회논문집
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• 제16권8호
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• pp.814-821
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• 2006

A structural coupling method is developed for the dynamic analysis of a nonlinear structure with concentrated nonlinear hinge joints or sliding lines. The component mode synthesis method is extended to couple substructures and the nonlinear models. In order to verify the improved coupling method, a numerical plate model consisting of two substructures and torsional springs, is synthesized by using the proposed method and its modal parameters are compare with analysis data. Then the coupling method is applied to a three-substructure-model with the nonlinearity of sliding lines between the substructures. The coupled structural model is verified from its dynamic analysis. The analysis results show that the improved coupling method is adequate for the structural nonlinear analyses with the nonlinear hinge and sliding mode condition.

• 소음진동
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• 제8권3호
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• pp.494-503
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• 1998

In this paper, in order to analyze dynamic characteristics of an automobile steering system consisting of many components, natural frequencies and transfer functions of each component and the total system are found on a FFT analyzer by experiments. Then, the data are transmitted to a commercial package program, CADA-PC. By analyzing the data, the mode shape of each natural frequency and damping values are obtained. Also, the function of a rubber coupling in column and telescoping effects on system are considered. C.A.E commercial programs are used to compare with the results of experiments. For the finite element modeling, I-DEAS is used. Data processing and post processing are operated on NASTRAN and XL, respectively. The ball-bearing and the linkage of shaft with column are modeled by spring element. Stiffness is modified from the results of experiments. The results of those show close agreement. In the mode shape of total system, wheel mode is dominant at lower frequency, while the column mode is main mode at higher. The role of rubber coupling in vibration isolation is clear on mode shape. Telescoping function makes natural frequency of column changed.

• Wind and Structures
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• 제14권3호
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• pp.239-252
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• 2011

The wind-induced mean, background and resonant responses of Beijing National Stadium are investigated in this paper. Based on the concepts of potential and kinetic energies, the mode participation factors for the background and the resonant components are presented and the dominant modes are identified. The coupling effect between different modes of the resonant response and the coupling effect between the background and resonant responses are analyzed. The coupling effects between the background and resonant components and between different modes are found all negligible. The mean response is approximately analogous to the peak responses induced by the fluctuating wind. The background responses are significant in the fluctuating responses and it is much larger than the resonant responses at the measurement locations.

• 한국소음진동공학회논문집
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• 제16권9호
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• pp.912-918
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• 2006

A modeling method for the vibration analysis of rotating multi-blade systems considering the coupling stiffness effect is presented in this paper. Blades are assumed as cantilever beams and the coupling stiffness effect originates from disc or shroud between blades. As the angular speed, hub radius ratio, and the coupling stiffness vary, the natural frequencies of the system vary. Numerical results show that the coupling stiffness is very important to estimate the natural frequencies. Along with the natural frequencies, associated mode shapes, critical angular speed, and critical hub radius ratio are obtained through the analysis.