• 전자공학회논문지SC
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• 제37권2호
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• pp.69-76
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• 2000

dual-modulus 프리스케일러는 제어신호의 값에 따라 입력신호를 두 개의 모듈러스(modulus) 중에서 하나의 값으로 나누는 회로이다. 본 논문에서는 일반적인 ratioed-NAND구조가 아닌, ratioed-NOR구조를 가진 새로운 고속 dual-modulus 프리스케일러를 제안한다. 제안하는 회로는 NMOS를 직렬 연결하는 대신 병렬 연결함으로써 기존 회로보다 더 고속으로 작동한다. 현대 0.65(m 2-poly 2-metal CMOS 공정 파라미터를 사용한 HSPICE 모의 실험 결과, 25℃의 온도와 5V전원전압의 환경에서, 40.7㎽의 전력을 소모하고 최대 동작 주파수는 2.8㎓라는 것을 얻었다. 제안하는 dual-modulus 프리스케일러는 셀룰라 라디오의 입력단에서 주파수 합성을 하는 데에 이용될 수 있을 것이다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.185-190
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• 2006

The correct estimation of the ionospheric delays is very important for the precise kinematic positioning especially in case of the long baseline. In case of triple frequency system, the ionospheric delays can be estimated from the measurements, but, in case of dual frequency system, the situation is not so simple. The precision of those supplied by the external information source such as IONEX is not sufficient. The high frequency component is neglected, and the precision of the low frequency component is not sufficient for the long baseline positioning. On the other hand, the high frequency component can be estimated from the phase range measurements. If the low frequency components are estimated by using the external information source or pseudo range measurements, a more reasonable estimation of the ionospheric delays may be possible. It has already been discussed by the author that the estimation of the low frequency components by using the external information source is not sufficient but fairly effective. The estimation using the pseudo range measurements is discussed in the present paper. The accuracy is not sufficient at present because of the errors in the pseudo range measurements. It is clarified that the bias errors in the pseudo range measurements are responsible for the poor accuracy of the ionospheric delays. However, if the accuracy of the pseudo range measurements is improved in future, the method would become very promising.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 춘계종합학술대회
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• pp.276-279
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• 1999

This paper proposes a design for microstrip patch antenna with dual resonance and dual polarization fed by proximity coupled quarter wavelength stub. The antenna characteristics are analyzed by the FDTD method with Mur's 2nd order ABC. From the simulation results based on the FDTD method, frequency characteristics of structure parameters such as the patch size and the offset feed are investigated. The numerical results are compared with the experimental results, and the comparison shows reasonable agreement for a design frequency.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.155-158
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• 1999

This paper describe the design and measurements of dual PLL for IMT-2000 cellular phone. As a result, dual PLL was well-operated in the RF frequency ranges of 2300 ~ 2360 MHz and If frequency of 380 MHz. The output power of -4.28 ㏈m, phase noise of -107.66㏈c/Hz at 100KHz frequency offset, lock time of 675.6$mutextrm{s}$ were obtained at 2330MHz. The output power of -4.78 ㏈m, phase noise of -115.28㏈c/Hz were also obtained at 380MHz.

• 한국전자파학회논문지
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• 제9권4호
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• pp.515-525
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• 1998

본 논문에서는 위성통신에서 단일 안테나로 송수신하기 위하여 12.5 GHz와 14.25 GHz 대역에서 각각 동작하 는 이중공진 안테나를 껄계 제작하고 특성을 살며보았으며, 이중 급천구조를 이용함으로써 기폰의 단일 급전 방 식 이중공진 안테나의 문제점인 송수신 신호의 분리 및 단일 편파 특성율 보완하였다. 이중급전 안테나의 방사소 자 경우 방사체의 폭과 길이는 각각의 단일 공진 안테나의 길이가 되고, 급전선의 청합의 경우에는 상대 급천선 에 의한 임피던스의 변화를 최소화시켰다. 또한 이를 배열 안테나로 확장시 공간상의 문제를 해결하기 위해서 마 이크로스트립선로와 동축선로를 혼합한 급전방식을 사용하여 이차원 $2\times2$ 배열 안테나를 껄계 제작하고 방사때 턴 및 주파수 특성 동을 측정하여 두 공진 주파수로 각각 사용 가능함올 확인하였다. 측정된 결과를 살펴보면 공진주파수는 셜계치에서 1.44 % 이하의 오차를 보였으며, 반사손실의 경우 -21 dB 이하의 값올 나타냈으며, 두 포트간 격리도는 또한 -21 dB 이하의 값올 나타냈다. 측정된 방사때턴으로부터 계 산된 directivity는 12.23 dBi를 나타냈으며, 사이드로브 레벨은 elevation 명면은 -12 dB 이하, azimuth 명면 은 -15 dB를 이하의 값을 나타냈다. 또한 교차 편파특성의 경우 elevation 명면과 azimuth 평면 모두 -17 dB 이하의 값을나타냈다.

• Journal of Positioning, Navigation, and Timing
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• 제3권1호
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• pp.11-16
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• 2014

A Satellite Based Augmentation System (SBAS) is a representative differential GNSS system, which is used for the navigation performance improvement of Global Navigation Satellite System (GNSS) users. SBAS has been developed focusing on the securement of user integrity so that it can be used for the navigation in aviation fields. Accordingly, the development of SBAS has been completed, and it has been actively used in the United States, Europe, and Japan. As the new satellite of Global Positioning System (GPS) recently started to broadcast new civil signals (L5 frequency), the methods for improving user navigation performance in SBAS using this signal have also been studied. In Korea, to keep pace with these circumstances, full-scale SBAS development is expected to start in 2014, and studies on dual-frequency SBAS using L1/L5 frequencies will also be performed. In this study, before the full-scale development of dual-frequency SBAS in Korea, a simulation was performed to predict the performance and analyze the expected effects.

• 제어로봇시스템학회논문지
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• 제6권8호
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• pp.719-726
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• 2000

A real-time precise positioning is possible with GPS carrier phase measurements with efficient integer ambiguity resolution techniques. It is known that more reliable and fast integer ambiguity resolution is possi-ble as the number of measurements increases. Most precise positioning systems use dual frequency measurements and the wide-lnae technique to resolve integer ambiguity. The wide-lane technique magnifies the measurement noise while it reduces the number of candidates to be examined. In this paper a new integer ambiguity resolution method using dual frequency is proposed The proposed method utilizes the relationship between the wide-lane single frequency and the narrow-lane ambiguities to resolve narrow-lane integer ambiguity after fixing the wide-lane integer ambiguity. Experiments with real data show that the proposed method gives fast and reliable results.

• Journal of Positioning, Navigation, and Timing
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• 제3권2호
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• pp.71-81
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• 2014

Time synchronization system using dual frequency bands is designed and the error sources are analyzed for alternative synchronized-pseudolite navigation system (S-PNS) which aims at military application. To resolve near/far problem, dual frequency band operation is proposed instead of pulsing transmission which degrades level of reception. In dual frequency operation H/W delay should be considered to eliminate errors caused by inter-frequency bias (IFB) difference between the receivers of the pseudolites and users. When time synchronization is performed across the sea, multipath error is occurred severely since the elevation angle between pseudolites is low so total reflection can be happened. To investigate the difference of multipath effects according to location, pseudolites are set up coastal area and land area and performances are compared. The error source related with tropospheric delay is becoming dominant source as the coverage of the PNS is broadening. The tropospheric delay is measured by master pseudolite receiver directly using own pseudorange and slave pseudorange. Flight test is performed near coastal area using S-PNS equipped with developed time synchronization system and test results are also presented.

• 한국해안해양공학회지
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• 제5권2호
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• pp.143-150
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• 1993

이중 주파수(Dual Frequency)를 사용한 Prototype형 천해 지층 탐사기를 사용하여 얻은 탐사 기록지가 제시되었다. 이중 주파수로는 3.5/100KHz 혹은 15/100KHz를 이용해서 고주파수에 의한 고해상도(High Resolution)을 얻고 동시에 저주파수(3.5~15KHz)에 의한 심층 투과력을 높이는데 본 연구의 목적이 있다. 특히 탐지하는 목표물이 Fresnel 반경에 비해서 매우 작을 때는 쌍곡선형 회절무늬(Hyperbolic Diffraction)가 나타나기 때문에 쉽게 목표물을 찾을 수 있다. 감쇠상수가 큰 모래층은 작은 감쇠상수를 갖고 있는 점토보다 지진파의 투과력을 약하게 만든다. 이와같이 이중 주파수의 동시 운용은 해저 지질. 모래와 점토(Silt/Clay) 분포 오니토 및 해양고고학 유물 탐사에 크게 활용할 수 있다.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권10호
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• pp.479-485
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• 2001

In this paper, we introduce a charge pump phase-locked loop (PLL) architecture which employs a precharge phase frequency detector (PFD) and a sequential PFD to achieve a high frequency operation and a fast acquisition. Operation frequency is increased by using the precharge PFD when the phase difference is within $-{\pi}{\sim}{\pi}$ and acquisition time is shortened by using the sequential PFD and the increased charge pump current when the phase difference is larger than ${\pm}{\pi}$. So error detection range of the proposed PLL structure is not limited to $-{\pi}{\sim}{\pi}$ and a high frequency operation and a higher speed lock-up time can be achieved. The proposed PLL was designed using 1.5 ${\mu}m$ CMOS technology with 5V supply voltage to verify the lock in process. The proposed PLL shows successful acquisition for 200 MHz input frequency. On the other hand, the conventional PLL with the sequential PFD cannot operate at up to 160MHz. Moreover, the lock-up time is drastically reduced from 7.0 ${\mu}s\;to\;2.0\;{\mu}s$ only if the loop bandwidth to input frequency ratio is regulated by the divide-by-4 counter during the acquisition process. By virtue of this dual PFDs, the proposed PLL structure can improve the trade-off between acquisition behavior and locked behavior.