• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.372-373
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• 2013

위성항법시스템(GNSS)에 대한 전파교란에 대응하기 위한 보완항법시스템인 eLoran은 고출력의 지상파를 사용하기 때문에 전파교란이 현실적으로 힘들다는 장점이 있다. eLoran 신호는 세계표준시(UTC)에 동기화 되어있어서 송신 출력에 따라 실내와 같이 GNSS 신호의 수신이 힘든 경우에도 정확한 시각(timing) 정보를 제공할 수 있다. eLoran을 이용한 시각 정보 제공은 미국 국방부(DoD)에서도 최근에 많은 관심을 보이고 있다. 또한 eLoran은 자체 데이터 채널을 보유하고 있어서 eLoran 보정 신호를 전송할 수 있고, 전파기만에 대비하여 eLoran 신호인증 기법을 적용할 수 있다. 전파교란의 영향을 받지 않고 데이터를 전송할 수 있기 때문에 안정적인 데이터 전송이 필요한 각종 분야에서 eLoran 데이터 채널의 활용이 가능하다. 현재 우리나라는 GNSS를 보완하는 위치 항법 시각(PNT) 시스템으로써 2018년 정상 운용을 목표로 eLoran 시스템 구축 사업을 진행하고 있다.

• Journal of Positioning, Navigation, and Timing
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• v.12 no.3
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• pp.229-236
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• 2023

As the importance and dependency of the positioning, navigation, and timing (PNT) information provided by the radio navigation satellite service (RNSS) increases, the vulnerability of RNSS to jamming can lead to significant risks. The signal design under the consideration of anti-jamming performance helps to provide service which is robust to jamming environment. Therefore, it is necessary to evaluate the jamming robustness performance during the design of new signals. In this paper, we introduce figures-of-merit (FoMs) that can be used for an anti-jamming performance analysis of designed signals of interest. We then calculate the FoMs, such as the quality factor (Q factor), tolerable jamming-to-signal ratio (tolerable J/S), and range to jammer (d) for legacy RNSS signals and analyze the results. Finally, based on the results of the analysis, we derive waveform design conditions to obtain good anti-jamming performance. As a result, this paper shows that the waveforms with wide bandwidth leading to good spectral efficiency provide strong anti-jamming performance.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.86-86
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• 2011

나노소재기술은 기존 소재로는 얻을 수 없는 새로운 기능 및 특성을 나타낼 수 있어 산업전반에 적용할 수 있는 최첨단집적기술이다. 그러나 나노입자를 섬유에 첨가하여 기능성 섬유를 생산하는 경우 응집이 발생하는 등의 다양한 문제점이 발생하는데 이를 극복하기 위해서는 사이즈 분포를 제어하는 기술, 표면처리를 통해 분산성을 향상시키는 기술, 나노입자와 섬유와의 상용성을 개선하는 기술 등이 해결되어야 한다. 본 연구에서는 고기능성 및 고부가가치 경편파일 니트 원단을 개발하기 위해 은(Silver) 나노입자가 균일하게 분산된 M/B(Master Batch)를 제조하였으며, 이를 PET와의 용융 혼합 방사함으로써 0.5denier(75D/144F)급 원사에 99.9%의 영구적인 항균/소취 기능을 부여하였다. 또한 개발된 극세사를 이용하여 다양한 경편파일 원단을 설계하고, 기모, 염색 및 날염 등의 공정을 거쳐 나노기술융합형 화학섬유소재를 이용한 기능성 침장 제품을 개발하였다.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.385-390
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• 2016

ELoran Systems can provide Position, Navigation, and Time services with comparable performance to Global Positioning Systems (GPS) as a back up or alternative system. High timing and navigation performance can be achieved by eLoran signals because eLoran receivers use "all-in-view" reception. This incorporates Time of Arrival (TOA) signals from all stations in the service range because each eLoran station is synchronized to Coordinated Universal Time (UTC). Transmission station information and the differential Loran correction data are transmitted via an additional Loran Data Channel (LDC) on the transmitted eLoran signal such that eLoran provides improved Position Navigation and Timing (PNT) over legacy Loran. In this paper, we propose a technique for adapting the delay time compensation values in eLoran timing receivers to provide precise time comparison. For this purpose, we have designed a system that measures time delay from the crossing point of the third cycle extracted from the current transformer at the end point of the transmitter. The receiver delay was measured by connecting an active H-field, an E-field and a passive loop antenna to a commercial eLoran timing receiver. The common-view time transfer technique using the calibrated eLoran timing receiver improved the eLoran transfer time. A eLoran timing receiver calibrated by this method can be utilized in the field for precise time comparison as a GNSS backup.

• Journal of Navigation and Port Research
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• v.36 no.6
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• pp.475-480
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• 2012

In order to establish eLoran (enhanced Long Range Navigation) system, it needs the advancement of receiver, transmitter, data channel addition for Loran information, differential Loran sites for compensating Loran-c signal and ASFs (Additional Secondary Factors) database, etc. In addition, the precise synchronization of transmitting station to the UTC (Coordinated Universal Time) is essential if Loran delivers the high absolute accuracy of navigation demanded for maritime harbor entrance. For better timing synchronization to the UTC among transmitting stations, it is necessary to measure and monitor the transmission delay of the station, and the correction information of the transmitting station should be provided to the user's receivers. In this paper we presented the measurement method of absolute delay of Pohang Loran transmitting station and developed a time delay measurement system and a phase monitoring system for Loran station. We achieved -2.23 us as a result of the absolute phase delay of Pohang station and the drift of Loran pulse of the station was measured about 0.3 us for a month period. Therefore it is necessary to measure the delay offset of transmitting station and to compensate the drift of the Loran signal for the high accuracy application of PNT (Positioning, Navigation and Timing).

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.437-443
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• 2019

In this paper, a new algorithm for the calculation of the range between an LTE base station (BS) and a user equipment (UE) using time-of-arrival (TOA) measurements of LTE signals is proposed. First, the cell identity (cell ID) of the received signal is acquired using the primary synchronization signal (PSS) and secondary synchronization signal (SSS) to identify the BS transmitted the signal. The proposed algorithm exploits the cell-specific reference signal (CRS), the reference sequence inserted in commercial LTE signals, to estimate the time delay using 2D cross-correlation. The obtained TOA estimations can be used to calculate the range employed from the known BS location. The performance of the proposed algorithm is evaluated with the experiment performed using real LTE signals transmitted from the commercial BS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.9
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• pp.1822-1829
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• 2016

DGPS Reference station is established in Korea for improvement of GPS navigation accuracy and needs of integrity. Recently, DGPS stations provide user positioning information on land as well as ocean. However, this paper investigated visibility and interference environment for performance degradation of Chung-ju DGPS reference station. In case of Young-do reference station, visibility and interference environment were satisfied with reference standard. In case of Chung-ju reference station, visibility was satisfied with 7 degree elevation angle. However, interference environment was not satisfied with reference standard of -50dBm. This paper proposed time differential measurement analysis method excluding error of signal noise for analyzing measurement error. Chung-ju reference station measurement analysis result is three times the error than on Young-do in Dec, 2015. In addition, this paper has confirmed measurement performance degradations because of reference station equipment problem. Future study will be carried out performance analysis of 17 DGPS reference station.