• 한국통신학회논문지
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• 제21권2호
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• pp.514-525
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• 1996

In this paper, Push-push Osciplier(Oscillator + Multiplier) has been analyzed by even-odd mode analysis method. A 10GHz DRO, an Osciplier using 10GHz DRO design method and an Osciplier using even-odd mode analysis method were designed, fabricated and tested to verify this method. The measured results verified the validity of the analysis method using even-odd mode analysis.

• Journal of electromagnetic engineering and science
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• 제17권2호
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• pp.86-90
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• 2017

In this study, a novel third-order bandpass filter, which is based on a rectangular closed loop resonator, is presented. By adding a series resonator to the conventional loop resonator, the resonator's even resonant mode is split into two modes, while the odd resonant mode is not affected. Therefore, by varying the values of the series resonator elements, the resonant frequencies of two even modes can be determined independent of the odd-mode resonant frequency. In the proposed triple-mode filter design, instead of using a lumped series resonator, a T-shaped transmission line is coupled to the resonator via a small gap. To verify the design method, a filter is designed at 2.4 GHz with a bandwidth of 100 MHz. The improved performances of the proposed triple-mode filter are compared with those of the conventional dual mode filter.

• 제어로봇시스템학회논문지
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• 제7권3호
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• pp.269-275
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• 2001

In land navigation applications, two kinds of GPS/DR integration schemes are commonly used; the loosely-coupled integration scheme and the tightly-coupled one. The loosely-coupled integration filter has a simple structure and is easy to implement. When the number of visible satellites is insufficient, however, it cannot calibrate the errors of the DR sensors. On the contrary the tigthly-coupled integration filter can sup-press the growth of the error in the DR output even when the visibility is poor. However, it has larger com-putation load due to the state dimension and is inconsistent because of the variation in the measurement dimension. This paper presents a GPS/DR integration scheme with dual integration mode. During when the number of visible satellites is sufficient, the proposed scheme operates in a loosely-coupled integration mode. When the visibility becomes poor, it is switched into a tightly-coupled integration mode. Consequently, the pro-posed scheme can calibrate the DR sensors even when the visibility is poor. In addition, its computation time remains constant even if the number of visible satellites increases. Field experiment results show that the performance of the proposed integration method is almost similar to that of the tightly-coupled one.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권5호
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• pp.238-242
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• 2001

In this paper, we extracted design parameters for re-entrant mode microstrip directional coupler using FE(finite element) calculations. The microstrip directional coupler suffers from a poor directivity due to effect of the inhomogeneous dielectric including both dielectric substrate and air in microstrip transmission lines. Thus, the phase velocity of even mode is not equal to that of odd mode. In order to improve the directivity of microstrip directional coupler, a novel re-entrant mode microstrip directional coupler was employed. In microstrip configuration, the high directivity can be reached by matching the even- and odd-mode effective phase velocities. Through the values of capacitance obtained from 2-dimensional FE calculations, the phase velocities for each mode and the design parameter were extracted for the proposed parallel coupled-line configuration. Based on the extracted design parameter with phase matching condition, we designed and fabricated a 30dB directional coupler at 0.85GHz. Experimental results show good performance with excellent, isolation and directivity.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.261-265
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• 2002

In the machining tool avoid vibration problem have an effect on high precision as well as statical and thermal characteristics. Therefore overcome this problem is essential to advance of machine tool and machining skill. Even though vibration arises owing to a variety of causes, in this paper vibration analysis of column as a major part of machine tool structures is presented. At this procedure vibration analysis applied to mode synthesis method using a attachment mode .

• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.339-346
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• 2015

Aerodynamic flow control phenomena were investigated with a low-current DC surface discharge plasma actuator. The plasma actuator was found to operate in three different discharge modes with similar discharge currents of about 1 mA or less. Stable continuous DC discharge without audible noise was obtained at higher ballast resistances and lower discharge currents. However, even with continuous DC power input, a low-frequency self-pulsed discharge was obtained at lower ballast resistances, and a high-frequency self-pulsed discharge was obtained at higher set-point currents and higher ballast resistances, both with audible noise. The Schlieren image reveals that the low-frequency self-pulsed mode produces a synthetic jet-like flow implying that a gas heating effect plays a role, even though the discharge current is small. The high-frequency self-pulsed mode produces pulsed jets in a tangent direction, and the continuous DC mode produces a steady straight pressure wave. Particle image velocimetry (PIV) images reveal that the induced flow field by the low-frequency self-pulsed mode has flow propagating in the radial direction and centered between the electrodes. The high-frequency self-pulsed mode and continuous DC mode produce flow from the anode to the cathode. The perturbed region downstream of the cathode is larger in the high-frequency self-pulsed mode with similar maximum speeds.

• 한국통신학회논문지
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• 제19권3호
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• pp.553-559
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• 1994

본 논문에서는 마이크로스트립-슬롯 결합 선로에 대한 Green함수를 스펙트럼 영역에서 유도하고, 수치적 결과를 정확히 얻기 위해 마이크로스트림 선로와 슬롯 부분에서의 전류분호에 대한 특이점을 고려한 기저함수를 이용한 Galerkin방법을 적용하여 선로의 특성 파라미터를 계산하였다. 특히, 마이크로스트림-슬롯 결합선로의 특성 중 마이크로스트립 선로에의한 우모드(even mode)와 슬롯에 의한 기모드(odd mode)의 특성에 의한 선로의 각 특성을 구하였고, 계산 결과값의 정확성을 비교하기 위해 기존의 데이터와 비교하였다.

• 대한전자공학회논문지
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• 제22권6호
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• pp.46-52
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• 1985

본 논문은 구형 마이크로스트립 안테나의 H-plane 상호결합에 관한 연구이다. 두 안테나의 상호결합을 계산하기 위해서 단일 마이크로스트립 패치의 교사저항을 구하였으며 결합된 전송선로를 even mode와 add mode로 분발하여 각 mode의 특성저항와 실효 유전률을 계산하였다. 이로부터 자계적으로 결합된 안테나를 S-band 주파수에서 S-parameter를 구한 결과 이론치와 실험치가 거의 일치함을 확인할 수 있었다.

• Journal of information and communication convergence engineering
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• 제2권3호
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• pp.198-201
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• 2004

In this paper, the discrete optimal control is made to have the robust property of Sliding mode controller. A augmented system with a virtual state is constructed for this objective and noble sliding surface is constructed based on this system. The sliding surface is the same as the optimal control trajectory in the original system. The states follow the optimal trajectory even if there exist uncertainties. The reaching phase problem of sliding mode control is disappear in this method.

• 전력전자학회논문지
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• 제17권4호
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• pp.315-321
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• 2012

The utility-interactive inverter with critical loads should supply continuous and stable voltage to critical loads even during the grid fault. The conventional control method which performs current control for grid-connected mode and voltage control for stand-alone mode undergoes the critical load voltage variation during grid fault. The critical load voltage may have large transient when the inverter performs mode transfer after the islanding detection. Recently, the indirect current control method which does not have the transient state during not only islanding detection but also the mode transfer has been proposed. However, since the voltage control is maintained even during the grid-connected mode it is difficult to detect the islanding. This paper proposes an active anti-islanding method suitable for the indirect current control method which does not have NDZ(Non-Detection Zone).