• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.578-581
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• 2004

유전체가 삽입된 공동 공진기는 유전체에 대부분의 전자계가 집속되어 있기 때문에, 도체 손실이 매우 적고 높은 Q값과 온도 안정성이 뛰어나다. 동일한 주파수에서 동작하는 다른 필터에 비해 상대적으로 작기 때문에 소형화에도 적합하다. 본 논문에서는 유전체가 삽입된 공동 공진기의 전자기 분포와 특성을 수치해석과 HFSS(High Frequency Structure Simulator)를 이용하여 분석하였고 이 결과를 토대로 HFSS를 이용한 순차적 방법을 도입하여 4-pole 이중모드 대역통과 필터를 설계, 제작하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.421-422
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• 2008

In this paper, CMOS RF front-end circuits for an L1/L5 dual-band global positioning system (GPS)/Galileo receiver are designed in $0.13\;{\mu}m$ CMOS technology. The RF front-end circuits are composed of an RF single-to-differential low noise amplifier, an RF polyphase filter, two down-conversion mixers, two transimpedance amplifiers, a IF polyphase filter, four de-coupling capacitors. The CMOS RF front-end circuits provide gains of 43 dB and 44 dB, noise figures of 4 dB and 3 dB and consume 3.6 mW and 4.8 mW from 1.2 V supply voltage for L1 and L5, respectively.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1212-1220
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• 2015

This article presents a new nonlinear joint (state and parameter) estimation algorithm based on fusion of Kalman filter and randomized unscented Kalman filter (UKF), called Kalman randomized joint UKF (KR-JUKF). It is assumed that the measurement equation is linear. The KRJUKF is suitable for time varying and severe nonlinear dynamics and does not have any systematic error. Finally, joint-EKF, dual-EKF, joint-UKF and KR-JUKF are applied to a CSTR with cooling jacket, in which production of propylene glycol happens and performance of KR-JUKF is evaluated.

• 전력전자학회논문지
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• 제19권6호
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• pp.522-529
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• 2014

This study proposes an isolation amplifier circuit for the sensing and feedback of inverter DC-link voltage, which is inevitable for the precise control of inverter output voltage. The isolation amplifier consists of a pulse-width modulator and a pulse transformer with dual secondary windings. The accuracy of the proposed circuit depends on the precise matching of filter parameters in dual secondary circuits. The influences of parameter inaccuracy on the amplifier performances are analyzed. A modified circuit is proposed to reduce the dependency on filter parameters. The validity of the proposed method is verified through simulation and experiment.

• Journal of Positioning, Navigation, and Timing
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• 제10권4호
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• pp.253-262
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• 2021

Global Navigation Satellite Systems (GNSS) based precise positioning using Real Time Kinematic (RTK) technique has been proposed as an enabler of the formation operation of moving vehicles. In RTK methods, the integer ambiguity of GNSS carrier phase measurements must be resolved. Although there have been many proposed algorithms for the integer ambiguity resolution, the widelane combination of carrier phase measurements and LAMBDA methods have gained the most popularity in literatures when dual frequency GNSS measurements were used. In this paper, we evaluated five alternative methods to determine relative positions of moving base and rover receivers; the round-off scheme of widelane carrier phase, instant least-squares and Kalman filter-based LAMBDA with widelane carrier phase, instant least-squares and Kalman filter-based LAMBDA with dual frequency measurements. The paper presented the performance of each method using flight test data, which showed their strength and weakness in the aspects of time-to-first-fix, ambiguity resolution success ratio, and relative position errors. Based on that, we provided practical recommendations of RTK operations for moving vehicles.

• 한국전자파학회논문지
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• 제15권7호
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• pp.644-652
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• 2004

본 논문에서는 급전면의 개방스터브와 접지면의 슬롯으로 구성되어 있는 초광대역의 저지대역을 갖는 저역통과 여파기 단위 구조를 캐스캐이드한 저역통과 여파기를 설계하였다. 초광대역의 저지대역을 갖는 저역통과 여파기 단위 구조는 급전면 개방 스터브에 의해 통과대역 특성을 결정하는 여파기 구조와 이러한 여파기의 dual 구조로 접지면 슬롯에 의해 통과대역 특성을 결정하는 여파기 구조가 있으며, 각각의 단위구조를 캐스캐이드함으로써 단일 여파기보다 더욱 향상된 저지대역과 skirt 특성을 얻을 수 있었다. 개방 스터브에 의해 통과대역 특성이 결정되는 구조와 dual 구조의 캐스캐이드 여파기는 각각 1.035㎓와 1.286㎓에서 -3㏈ 차단 주파수를 가지며 저지대역은 두 구조 모두 -20㏈ 기준으로 20㎓ 이상의 광대역을 이루었다.

• 상하수도학회지
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• 제9권4호
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• pp.107-114
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• 1995

The raw drinking water quality is getting worse because of the winter drought and the conventional treatment system is'nt suitable to obtain the satisfied quality of water. So, the advanced water system, BAC(Biological Activated Carbon) process is said to be effective to remove dissolved organics and ammonia nitrogen. In our study, the BAC pilot plant using Nak-dong river water is tested in low temperature. Following results are found from the study. The ammonia nitrogen removal rate of BAC system using wood-based carbon (PICABIOL) was 99% in $6^{\circ}C$ temperature. Chlorine dosage in wood-based BAC effluent was reduced to 67% of that in sand filtered wate. It resulted from the removal of ammonia nitrogen. Also, THM formed by chlorine addition in wood-based BAC effluent was decreased to 65% of that in sand filtered water. In the case of dual-filter, the removal efficiency of ammonia nitrogen was increased 30% more than in conventional sand filter. According to this result, the ammonia nitrogen load to BAC system could be lessened by the use of dual-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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.369-372
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• 1994

In this paper, a voltage type dual PWM converter which achives the bidirectional power flow between a AC supply and a DC bus voltage is described. In PWM modulator, there exist a time difference between the sampling time and carrier wave, it achieves stable modulation even the disturbance in the synchronous AC source voltage. And this paper proposes the compensation method and the control method related a disturbance of synchronous signal using the low pass filter and phase shifter for the stable modulation. As a result the voltage type dual PWM converter makes the imput current wave as sinusoid, and performs the high power factor driving.

• 대한수학회지
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• 제54권2호
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• pp.613-626
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• 2017

For the overdetermined linear system, when both the data matrix and the observed data are contaminated by noise, Total Least Squares method is an appropriate approach. Since an ill-conditioned data matrix with noise causes a large perturbation in the solution, some kind of regularization technique is required to filter out such noise. In this paper, we consider a Dual regularized Total Least Squares problem. Unlike the Tikhonov regularization which constrains the size of the solution, a Dual regularized Total Least Squares problem considers two constraints; one constrains the size of the error in the data matrix, the other constrains the size of the error in the observed data. Our method derives two nonlinear equations to construct the iterative method. However, since the Jacobian matrix of two nonlinear equations is not guaranteed to be nonsingular, we adopt a trust-region based iteration method to obtain the solution.