• 한국전자통신학회논문지
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• 제13권4호
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• pp.685-694
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• 2018

본 논문에서는 Ku대역 추적레이더의 핵심부품인 고주파 헤드 내 주파수 믹서(혼합기)의 설계 및 제작 결과에 대해서 다룬다. 단일종단(Single-Ended) 및 단일평형(Single-Balanced) 믹서의 단점을 보완하기 위해서, Fine-Line 구조의 평형(Balanced) 믹서를 설계하여 낮은 변환손실 특성을 가지도록 하였으며, Ku대역 RF신호를 입력받아 L밴드 IF신호를 생성하도록 하였다. 제작된 믹서에 대해서 Ku밴드 5개 샘플주파수를 대상으로 실험한 결과, 최대 잡음지수(Noise Figure Max) 6.823dB, 이득(Gain) 4.159dB ~ 4.676dB, 통과대역(Band Pass) 61MHz의 값을 확인하였다.

• 한국정보통신학회논문지
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• 제3권2호
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• pp.389-396
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• 1999

본 연구에서는 수중에서 진행하는 물체에서 전달되는 방사신호의 주파수스펙트럼으로부터 추출되는 토널과 주파수선과 같은 협대역 특징을 이용하여 미지의 다중 수중 이동물체를 효율적으로 판별하고 추적하기 위한 알고리즘을 제시한다. 제안한 알고리즘은 계층 구조의 신경망으로 구성된다. 조향 방위각에 대한 광대역에너지와 방위별 협대역 에너지를 검출하여 미지의 수중이동물체의 출현 방위각을 추정하고 이를 토대로 물체를 추적하는 기존의 기법으로는 물체들이 서로 인접하거나 교차하는 경우에 추적에 실패할 가능성이 높다. 그러나 제안한 알고리즘을 사용하여 실제 신호를 포함하는 시뮬레이션 시나리오에 대해 물체 추적 실험을 행한 결과, 특히 인접하거나 교차하는 물체들의 추적에 성공적인 성능을 나타내었다.

• Smart Structures and Systems
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• 제14권6호
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• pp.1197-1220
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• 2014

Accurate actuator tracking is critical to achieve reliable real-time hybrid simulation results for earthquake engineering research. The frequency-domain evaluation approach provides an innovative way for more quantitative post-simulation evaluation of actuator tracking errors compared with existing time domain based techniques. Utilizing the Fast Fourier Transform the approach analyzes the actuator error in terms of amplitude and phrase errors. Existing application of the approach requires using the complete length of the experimental data. To improve the computational efficiency, two techniques including data decimation and frequency decimation are analyzed to reduce the amount of data involved in the frequency-domain evaluation. The presented study aims to enhance the computational efficiency of the approach in order to utilize it for future on-line actuator tracking evaluation. Both computational simulation and laboratory experimental results are analyzed and recommendations on the two decimation factors are provided based on the findings from this study.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1121-1124
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• 2004

Aging test to estimate life property of polymer insulator is executed through several international standard such as IEC 61109 and CEA tracking wheel test, but is not getting clear conclusion yet. There are two methods in the diagnosis method of polymer insulator such as off-line and on-line. The diagnosis methods in off-line are external condition analysis by the eye, contaminant analysis on surface, surface analysis, pollution withstand voltage test, power frequency flashover voltage test, lightning impulse flashover test, tensile fracture load test and flexural load test. The diagnosis methods in off-line most are the method for virgin and last aged sample. However, the diagnosis method in on-line is method that can be evaluate sample state as progressing continuously aging test in beginning, The diagnosis method in on-line is arranged as following: leakage current measurement, electric field, surface state investigation, thermal image, emitting light measurement and then so. In this paper, the tracking performance of polymer insulator with salt solution which is added surface active agent. The diagnosis of insulator sample has been analyzed by leakage current and visual examination.

• 한국음향학회지
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• 제15권6호
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• pp.104-109
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• 1996

수동 소나 시스템에서는 표적을 탐지, 추적 및 식별을 위하여 표적의 방사 소음으로부터 발생되는 주파수선을 주요 특징 인자로 활용한다. 이 연구에서는 수중 표적의 방사 소음으로부터 시간 영역의 표본화된 데이타를 이용한 불안정 주파수선의 추출 기법에 대하여 연구하였다. 불안정 주파수선은 시간에 따라 주파수선이 변화되어 나타나므로 불안정 주파수선 추출을 위하여 비선형 시스템에 유용한 확장 칼만 필터 알고리듬을 적용하였다. 모의 실험 및 표적 신호에 적용하여 제시한 방식이 불안정 주파수선을 추출할 수 있음을 보인다.

• 제어로봇시스템학회논문지
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• 제16권2호
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• pp.177-187
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• 2010

A MTG (Multimode Tracking and Guidance) system is employed to compensate for the limitations of individual seekers such as RF (Radio frequency) or IIR (Imaging Infra-red) and to improve the overall tracking and guidance performance in jamming, clutter, and adverse weather environments. In the MTG system, tracking filter, data association, and data fusion methods are important elements to maximize the effectiveness of precision homing missile guidance. This paper proposes the formulation of a Kalman filter for the estimation of line-of-sight rate from seeker measurements in missiles guided by proportional navigation. Also, we suggest the HPDA (Highest Probability Data Association) and data fusion methods of the MTG system for target tracking in the adverse environments. Mont-Carlo simulation is employed to evaluate the overall tracking performance and guidance accuracy.

• 수산해양교육연구
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• 제19권3호
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• pp.478-490
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• 2007

A technology of ultrasonic biotelemetry for tracking fish behavior is investigated. The ultrasonic biotelemetry system is constituted by a transmitter and a receiving system. Because a pinger was mainly used for the transmitter, the capability for pinger to possess was investigated and the efficient usage for pinger was examined. A source pressure level and a frequency were synthetically examined so that pinger could realize small size, a light weight, and a long life time. The receiving system is divided roughly into directional hydrophone systems and acoustic positioning systems by the receiving method. The directional hydrophone system is divided into single beam and multiple beam with the number of hydrophone, and the acoustic positioning systems is divided into LBL (Long Base Line), SBL (Short Base Line), and SSBL (Super Short Base Line) on the basis of base line. The present situation, the merits and demerits, and the principle of each receiving method were investigated in detail, and the efficient usage for each receiving method were examined.

• 대한전기학회논문지
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• 제45권2호
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• pp.294-300
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• 1996

In hydro-generator, a groundwall insulation of stator windings gradually deteriorates due to mechanical, thermal, electrical and environmental stresses. These stresses combine to result in loose windings, delamination of the stator insulation and/or electrical tracking of the endwinding, all of which can lead to stator insulation failures. Conventionally, off-line tests such as partial discharge measurement, DC/AC current and .DELTA.tan.delta. tests has been used for estimation of winding condition. However, off-line test requires large power supply and generator outage. In addition, major cause of insulation problems such as loose wedges and slot dischages may not be found with off-line diagnoses. This paper introduces the on-line partial discharge measurement techniques using frequency spectrum analyzer(FSA) for the generator stator windings. The experimental results from the UIAM #1 hydro-generator confirms a optimistic application of on-line generator diagnosis method as a reliable tool for evaluation of winding condition.

• 대한전기학회논문지:전력기술부문A
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• 제55권12호
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• pp.544-548
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• 2006

The instantaneous frequency gives a frequency value at a time instance. Thus, it is natural to use the instantaneous frequency for detecting disturbances of voltage signal in power line. Various instantaneous frequency estimators are introduced. By applying to different types of disturbed signals, we show the estimators' ability to classify flickers. Also, the computational costs are compared between different instantaneous frequency estimators. The Prony's method (PRONY) and the modified covariance method (MCOV) need relatively smaller amount of calculation than the Teaser-Kaiser energy operator based estimator (DESA II). For an AM-FM modulated signal, the tracking performance of different instantaneous frequency estimators is also compared. Through simulation, it is shown that MCOV produces less variant frequency estimation values than DESA II and PRONY method.

• 전자공학회논문지SC
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• 제45권6호
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• pp.141-148
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• 2008

신재생 에너지 분야에서 각광받고 있는 계통 연계형 태양광 인버터에서는 계통과의 연계를 위해서 반드시 계통의 위상 정보가 필요하다. 본 논문에서는 계통 연계형 태양광 발전 시스템에서의 위상 동기화 방법으로 원하는 기준 신호의 주파수를 구하여 동기신호로 사용하고, DFT(Discrete Fourier Transform) 알고리즘을 이용하여 기준 신호와의 위상차를 구하여 위상차만큼 보상하는 PLL(Phase Locked Loop)의 순시 추종방법을 제안하였다. 또한 DFT 연산에 사용되는 한주기 값들을 샘플링 할때마다 보정 위상 값을 구하는 방법과 특정 주파수의 기준신호에 대한 주파수 및 위상 추종뿐만 아니라 다양한 주파수 신호에 대한 주파수 및 위상을 추종하는 방법을 적용하여 시뮬레이션과 실험을 통해 본 논문의 타당성을 검증하여 유효성을 보이고자 한다.