• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.1271-1275
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• 1987

With the stochastic process which consists of the harmonic sinusoid and the white nosie, the power spectrum of background EEG is estimated by the Pisarenko Harmonic Decomposition. The estimating results are examined and compared with the results from the maximum entropy spectral estimation, and the optimal order of this model can be determined from the eigen value's fluctuation of autocorrelation of background EEG. From the comparing results, this paper ensures that this method is possible to analyze the power spectrum of background EEG.

• 천문학회보
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• 제39권2호
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• pp.79.2-79.2
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• 2014

Galactic radio pulsar population is diverse. So far about 2300 radio pulsars are known in the Milky Way, in addition to Large and Small Magellanic Clouds. Radio pulsar observations at a few hundreds MHz up to ~10 GHz have been active and they are proved to be fruitful. Low frequencies are preferred mainly because of the steep ratio spectrum of pulsars. However, developments in pulsar backends (e.g. a wide-band spectrometer) and improved system sensitivities make it possible to observe pulsars at higher frequencies using large, single-dish telescopes up to ~18 GHz. Going forward, mm-wavelength observations is expected to open a new window in pulsar astronomy. In particular, frequencies well above ~15 GHz are pre-requisite to detect pulsars in the Galactic Center where radio pulsed signals are severely scattered by interactions with the interstellar medium. Recent discoveries strongly imply that there are subsets of pulsars with an apparently flat spectrum, such as magnetars. In April 2014, the first pulsar (magnetar) was discovered only 3 arcmin from Sgr A*, PSR J1745-2900. We will present a brief overview on pulsar populations focusing on those observable at high frequencies. We will also discuss prospects of pulsar observations in mm-wavelengths and how we can utilize the Korean VLBI network.

• 한국안전학회지
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• 제12권4호
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• pp.191-200
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• 1997

This paper discusses prediction of the sound pressure level produced by simple engine exhaust systems(plain pipe, plain expansion chamber pipe, plain expansion chamber with internally extended inlet and outlet pipe, perforated pipe enclosed in a plain expansion chamber) and a computer program has been developed which predicts the sound pressure level and the frequency spectrum. The program utilizes unsteady flow gas dynamic theory and acoustic theory to predict the pressure-time history in the exhaust system and the mass flow rate-time history at the open end of the system and the sound pressure levels(1/3 Octave band levels) and the frequency spectrum in semi-anechoic room. The predictions are compared with measured levels and show a high degree of correlation.

• 한국통신학회논문지
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• 제12권3호
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• pp.224-238
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• 1987

본 논문에서 제안된 스펙트럼 분석장치는 개루프 방식의 VCO를 모듈러 함수를 이용한 PLL 주파수 합성기로 대치시킴으로써 단일루우프의 주파수 합성기로 개개의 다른 주파수 대역 및 채널간격을 얻을 수 있었다. 스펙트럼의 추출은 자승검파방식을 이용함으로써 종래의 포락선 검파방식보다 입력감도를 개선할 수 있었고 Z80 마이크로프로세서를 이용한 제어기는 주파수 합성기를 제어하는 동시에 추출된 스펙트럼을 메모리에 저장함으로써 비주기성 신호의 분석을 가능케 하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1995년도 춘계학술발표회 논문집
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• pp.65-92
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• 1995

The final aim of our research project is a study on assessment of automatic steering system of ships in open seas. In order to achieve this aim we need to know the characteristics of each component of the system and also to know the characteristics of disturbance to ship dynamcis. In this paper we provide calculation method of irregular disturbance to ships in autopilot navigation in open seas and also show calculation examples about two kinds of ship ore carrier and fishing boat. The disturbance consists of irregular wave and random wind, The disturbance is calculated as equivalent yaw angular velocity. Each spectrum and time history of disturbance are reasonably evaluated. Further investigation concerning to performance index of autopilot system and energy loss related to automatic course keeping will be dealt with in another paper,

• 한국항해학회지
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• 제19권2호
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• pp.1-12
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• 1995

The final aim of our research project is a study on assessment of automatic steering system of ships in open seas. In order to achieve this aim, we need to know the characteristics of each component of the system, and also to know the characteristics of disturbance to ship dynamics. In this paper, we provide calculation method of irregular disturbance to ships in autopilot navigation in open seas, and also show calculation examples about two kinds of ship, ore carrier and fishing boat. The disturbance consists of irregular wave and random wind. The disturbance is calculated as equivalent yaw angular velocity. Each spectrum and time history of disturbance are reasonably evaluated. Further investigation concerning to performance index of autopilot system and energy loss related to automatic course keeping, will be dealt with in another paper.

• 수산해양기술연구
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• 제34권2호
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• pp.165-173
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• 1998

When an automatic course-keeping is concerned, as is quite popular in modem navigation, the closed-loop steering system consists of autopilot device, power unit (or telemotor unit), steering gear, magnetic or gyro compass and ship dynamics. In order to estimate automatic steering system of ships in open seas. we need to know the characteristics of each component of the system, and also to know the characteristics of disturbance to ship dynamics. In this paper, I provide calculation method of imposing irregular disturbance to autopilot navigation system of the ship in open seas, and also show calculation examples about fishing boat. The disturbance consists of the irregular wave and the fluctuating component of wind. Finally, The disturbances are calculated in terms of equivalent yaw angular velocity. Each spectrum and time history of disturbance are reasonably evaluated.

• 한국환경과학회지
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• 제17권12호
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• pp.1373-1380
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• 2008

Anthracene appended new host compounds have been synthesized by imine reaction. Fluorescent open chain host compounds Trisanthryl-tris(2-aminoethyl)imine 1 was synthesized from the reaction of tris(2-aminoethyl)amine and anthracene-9-carboxaldehyde in EtOH. Tris-10-chloroanthryl-tris(2-aminoethyl)imine 2 was synthesized from tris(2-aminoethyl)amine and 10-chloro-9-anthraldehyde in EtOH. The structures of all reaction product were identified by $^1H$ NMR, $^{13}C$ NMR, GC/MS, FAB Mass, IR spectrum and DSC. Cation complexation behavior was investigated by fluorescence spectroscopy measurements. The capability of transition metals cation recognition between fluorescent open chain host compound 1, 2 were investigated with $Co^{2+},\;Ni^{2+}\;and\;Cu^{2+}$. The fluorescence intensity was increased by host compounds corresponding guest cations. The relative order of fluorescence intensity changes were $Co^{2+}>Cu^{2+}>Ni^{2+}$. Compound 2 is very sensitive fluorescent sensor of $Co^{2+}$ ion.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1984년도 추계학술발표회논문집
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• pp.43-47
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• 1984

This paper describes the mean time delay and its variance before transition from search to lock mode by means of signal flow graph and its transfer function. A relation between hit probability and search stage number is presented with the comparison of the open loop and closed loop. From these results optimum transition probability which we must hold can be obtained.

• 한국위성정보통신학회논문지
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• 제7권1호
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• pp.39-47
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• 2012

현재의 주파수 분배상황을 살펴보면 대부분의 주파수 대역이 고정 할당되어 있으며 특히 무선통신 환경에 가장 적합한 저주파 대역은 거의 사용할 여지가 없다. 이에 인지무선 기술은 무선통신환경에서 주파수 부족 문제를 해결하고 주파수 활용도를 높이기 위한 중요한 기술로 대두되고 있다. 본 논문에서는 SDR (Software Define Radio)플랫폼인 USRP (Universal Software Radio Peripheral) 보드와 SDR 개발 툴킷인 GNU Radio를 이용하여 실제 인지무선(Cognitive Radio : CR) 시스템에서 데이터를 송, 수신하였다. 구체적으로 스펙트럼 센싱 기술을 이용하여 면허 사용자의 주파수 사용 여부를 감지하여 이 정보를 데이터베이스로 넘겨준다. 정보를 넘겨받은 데이터베이스에서는 유전자 알고리즘을 이용하여 최적의 송신전력과 대역폭, 채널 정보를 인지무선 기기에 보내어 주어 인지무선 기기가 면허 사용자에게 아무런 간섭을 주지 않고 데이터 통신을 할 수 있도록 하였다.