• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.04a
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• pp.156-162
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• 1998

The whistle is a very important information source for the safety navigation under foggy weather. But navigator has no concern about this , because it must be achieved by human hearing sense and considered as a vague signal. If the range and relative bearing of signa source can be detected automatically, it would be very useful system for preventing marine casualties making a lot of economic loss and environment pollution. Before the algorithm of 2-dimensinal sound source tracking system was reported . This paper describes the method that can obtain thetime lag between three signas and the theory of cross-correlation analysis and subtraction method for cauculating the time lag by using the digital signal data sequences. And a series of experiments were carried out for various position of sound source in the range from 200m to 530cm.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.671-676
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• 2010

In this paper, an effort has been made to design and develop a meteorological data logger for meteorological purpose. This data logger is proposed to be included various sensor interface that used in weather sensors. Besides, numbers of meteorological process libraries are added into this data logger to make it able to perform as unattended weather monitoring system. Data output of this data logger are also design to support multiple protocol that commonly used in data logger, and several communication devices that commonly used in the market. Each data that logged will be logged together with date and time and able to retrieve via serial port using hyper terminal. It is also configurable via serial port.

• Journal of Navigation and Port Research
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• v.42 no.5
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• pp.317-322
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• 2018

Marine weather information provided for vessels is mainly offered by radio devices such as NAVTEX, Weather Fax., and others. However, the information is too general for large areas, and lacks more detail. So, many seafarers are disinclined to use the information to initiate proper readiness of vessels' safety, avoiding marine accidents such as grounding, hull and cargo damage, but cannot develop an optimal and economical navigation plan, considering the inadequate level of low precision weather information. The purpose of this paper is to develop a strong wind warning system, based on the digital anemometer installed on the bridge. This study analyzed the data on 10-minutes average wind speed, when the vessel's grounding accidents happened in Korean ports. Results reveal that the vessel's strong wind warning algorithm, can estimate the growing of wind speed two-three hours in advance.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.06a
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• pp.307-309
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• 2011

국토해양부에서는 우리나라 해안과 내륙에 17개소의 기준국을 구축하여 전국토에서 실시간 DGNSS(Differential Global Navigation Satellite System) 측위가 가능하도록 서비스를 제공하고 있다. 그러나 현재 제공하는 DGNSS 서비스는 사용자가 비콘(beacon) 수신기를 이용해야만 하는 한계와 이로 인한 응용 범위의 제약을 받고 있으며, 위치정보의 폭발적 사용 증가로 인해 다양한 분야에서 더 높은 정밀도 및 정확도를 요구하고 있는 실정이다. 따라서 국토해양부에서는 국내에서 보편적 정보제공 매체로 사용 중인 지상파 DMB(Digital Multimedia Broadcasting)를 이용한 가상 기준국 기반 DGNSS 서비스 제공 시스템을 구축함으로써 DGNSS 서비스를 상용화하고 광역화 할 계획이다. 이 연구에서는 국토해양부에서 개발 중인 지상파 DMB 기반 DGNSS 서비스 기술개발 현황을 소개하고, 이를 상용화 및 광역화하기 위한 방안을 제시하였다.

• Journal of Navigation and Port Research
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• v.42 no.2
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• pp.79-86
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• 2018

Common Maritime Data Structure (CMDS) is commonly used by shore and ship users in e-Navigation data domain. In the overarching of e-Navigation architecture, IHO uses S-1XX, a digital exchange standard for next-generation marine information, as data exchange standard. The current CMDS has the advantage of intuitively recognizing the overall structure of e-Navigation. However, it has disadvantage in that it does not allow stakeholders to easily understand benefits that e-Navigation can provide when implementing e-Navigation. In this study, the direction of improving existing system for effective e-Navigation implementation was proposed considering RCOs (Risk Control Options) with expected composition of ship/ shore/ communication system by sector.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.411-414
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• 2006

본 논문은 다양한 GPS 재밍대응 기술 중에서 안테나 기반의 CRPA(Controlled Reception Pattern Antenna) 시스템에 관한 소개 및 안테나의 널(null) 패턴 합성에 필요한 핵심 모듈인 디지털 I/Q 벡터모듈레이터(Vector Modulator)를 이용한 GPS용 $2{\times}2$ CRPA 패턴 제어방법에 관한 연구 내용이다. 일반적으로 시스템에서 미리 결정된 방향으로 만들어진 안테나 빔을 이용한 위상배열안테나(phased array antenna)와는 달리 CRPA 구조의 GPS 위성수신용 적응배열안테나(adaptive array antenna)는 각 안테나 소자(element)로부터 수신된 신호들을 실시간으로 해석하여, GPS 배열 안테나의 패턴 특성을 제어한다. 본 연구에서는 $2{\times}2$ 배열 정사각(square) 구조의 CRPA를 채택했으며, 재밍신호 방향으로 널(null) 패턴을 합성하기 위한 방법으로 PC에서 제어 가능한 DAC(Digital to Analog Converter)을 이용하여 I/Q 벡터모듈레이터로 인가되는 RF신호의 위상(phase) 및 진폭(amplitude)을 조절한다. 이때 원하는 널(null) 패턴이 합성되도록 네 개의 각 안테나 소자 쪽으로 8채널의 복소가중치(complex weight)를 인가한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.223-228
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• 2006

The main purpose of this paper is to describe the code tracking performance of a non-coherent digital delay lock loop (DLL) or coherent DLL while tracking GNSS signal in the presence of signal masking. The masking effect is usually caused by buildings that obscure the signal in either a periodic or random manner. In some cases, ideal masking is used to remove random or periodic interference. Three types of the masked signal are considered - no masking, periodic masking, and random masking of the signal input to the receiver. The mean time to lose lock (MTLL) of the code tracking loop are evaluated, and some numerical result and simulation results are reported. Finally, the steadystate tracking errors on the performance of the tracking loop in interference environment are also presented.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.247-250
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• 2006

Based on the possibility theory and the fuzzy set, the Maximum Possibility Estimation method and its applications in kinematic GPS positioning are presented in this paper. Firstly, the principle and the optimal criterion of the Maximum Possibility Estimation method are explained. Secondly, the kinematic GPS positioning model of single epoch single frequency with baseline length constraint is developed. Then, the authors introduce the artificial immune algorithm and use this algorithm to search the global optimum of the Maximum Possibility Estimation model. The results of some examples show that the method is efficient for kinematic GPS positioning.

• Journal of Navigation and Port Research
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• v.28 no.2
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• pp.135-140
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• 2004

A purpose of developing a sound source tracking system in this paper is to reduce the noise efficiently from the received signal by microphone array and measure the signal's time delay between the microphones. I have applied the wavelet analysis algorithm to the system and calculated the sound source's relative position For the performance evaluation, I have compared with the results of utilizing the digital filtering methods based on the FIR LPF using Kaiser window function and the inverse Chebyshev IIR LPF. As a result, I have confirmed the fact that 'time-scale' filter using inverse discrete wavelet transform was suitable for this system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.19-21
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• 2019

In this paper, we introduce VDES system and multipath channel model for maritime wireless digital communication. And we studied the influence of multipath for bit-error ratio performance by computer simulation. Next we propose time-domain adaptive equalizer to treat the influence of multipath, and review the simulation result for necessity of applying the adaptive equalizer.