• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.6
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• pp.1323-1329
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• 2014

In this paper, we analyzed efficient decoding scheme with FTN (Faster than Nyquist) method that is transmission method faster than Nyquist theory and increase the throughput. we proposed viterbi equalizer model to minimize ISI (Inter-Symbol Interference) when FTN signal is transmitted. the proposed model utilized interference as branch information. In this paper, to decode FTN singal, we used turbo equalization algorithms that iteratively exchange probabilistic information between soft Viterbi equalizer (BCJR method) and LDPC decoder. By changing the trellis diagram in order to maximize Euclidean distance, we confirmed that performance was improved compared to conventional methods as increasing throughput of FTN signal.

• Journal of Ocean Engineering and Technology
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• v.37 no.5
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• pp.190-197
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• 2023

In the shipbuilding and marine industry, digital transformation activities are promoted primarily by large shipyards. However, bottlenecks are observed across value chains, and digital transformation effects are reducing because of the cost and technical challenges encountered by supplies. In this study, we proposed a win-win cooperation model for large, small, and medium-sized companies using digital transformation based on the characteristics of the shipbuilding and marine industry through case studies. We investigated the digital transformation progress in German and Korean small and medium-sized enterprises (SMEs). In addition, we identified information-sharing methods and management challenges encountered in enterprise resource planning and manufacturing execution systems in the collaboration process of pipes, panels, blocks, etc. of SMEs that are suppliers of a Korean shipyard, and clarified communication by building a platform based on a common format between shipyards and suppliers. Further, we proposed a standard model of a digital transformation system for enhancing the collaboration between large companies and suppliers and proposed a basic plan including strategies to efficiently and effectively build a digital transformation system based on the standard model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.854-860
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• 2005

The information on maritime affairs in South Korea has been provided by ministry of maritime affairs and Fisheries, National Fisheries. Research and Development Institute, Korea Ocean Research and Development Institute, National Oceanographic Research Development Institute, and the information on marine environment and maritime environment has been lively producing by laborarories, universities and other Private-run institute.

• Journal of information and communication convergence engineering
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• v.10 no.3
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• pp.225-230
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• 2012

The Korean nationwide differential global positioning system (NDGPS) reference station transmits a global positioning system (GPS) enhancement signal using minimum shift keying modulation with a 200 bps data rate. The ocean-based DGPS covers the service area of 100 NM with 300 W output power; on the other hand, the land-based DGPS transmits the output power of 500 W, which covers the service area of 100 km. The DGPS reference stations with high output power can radiate spurious signals, which may act as interference sources affecting the other DGPS reference stations or the wireless ground stations that utilize the medium frequency band. In this paper, the radiation spectrums of the DGPS reference stations are measured and analyzed in the spurious domain. The DGPS radiation spectrums are evaluated from the perspective of the interference effect.

• Journal of information and communication convergence engineering
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• v.9 no.4
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• pp.363-368
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• 2011

The DGPS transmits the enhancement signal to GPS using the medium frequency band. The NDGPS service that covers the Korean peninsula has been started since 2009. The service area of ocean-based DGPS(maritime-DGPS) reference stations covers the 100NM, but land-based DGPS(land-DGPS) covers 80km service area less than that of maritime DGPS. The DGPS's antenna has the top-loaded monopole antenna type. Top-loaded monopoles are the logical antennas to be used in order to get a low profile antenna and a performance according to the broadcaster and communication needs. The antenna needs to get the ground plane with good conductivity characteristics and flat ground plane without obstacle near to the transmitting antenna. In this paper, the radiation characteristics of an equivalent MF antenna are analyzed in view points of the ground conductivity and the ground plane with obstacle near to the antenna.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.85-86
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• 2012

e-Navigation strategy IMO promotes is defined as it is necessary to network to provide various maritime safety information to in land and on board users, and it is expected to provide a large amount and diverse kinds of maritime spatial information services to them frequently. However, as there are some limits to transmit that by current mobile maritime communication technologies, it is required to simplify and optimize the information. In this study, tree node and convex hull method is applied to S-100 SD spatial information to generalize and we arranged the efficiency and effect of generalization by storing in XML form which can be used in general.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2570-2572
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• 2005

본 논문에서는 다중 경로 오차 제거를 위해, 4개의 상관값을 제공하는 가중 협대역 상관기(Weighted Narrow Correlator) 구조에 대해 제안한다. 가중 협대역 상관기는 서로 다른 칩 간격을 가지는 여러 상관값 출력에 가중치를 주어 다중경로 신호에 의한 코드 위상 측정 오차를 줄이는 방법이다. 우선 다양한 지연시간 및 신호 감쇄를 가지는 다중 경로 신호에 대하여, 가중치에 대한 수신기의 성능 변화를 분석하고 이를 통해 최적의 가중치를 선택하였다. 제안한 상관기는 일반 수신기와 동일한 신호 획득능력을 가지며, 협대역 상관기보다 개선된 다중경로 오차 제거 능력을 보인다. 가중 협대역 상관기의 성능은 시뮬레이션을 통한 의사거리 측정치의 비교를 통해 검증하였다.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2567-2569
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• 2005

본 논문에서는 해양분야에 적용 가능한 GPS(Global Positioning System) 코드, 반송파, 항법 메시지 감시 기법을 제안한다. GPS를 구성하고 있는 위성, 지상 제어국, 사용자부에 내재한 고장 요인들에 대하여 분석하고 이를 바탕으로 각 고장에 대응할 수 있는 검사기법들을 제시한다. 제시하는 검사기법은 DGPS 기준국에서 수행할 수 있는 검사 기법으로 신호 감시 기법(SQM, Signal Quality Monitoring), 데이터 감시 기법(DQM, Data Quality Monitoring), 측정치 감시 기법(MQM, Measurement Quality Monitoring)으로 구성된다. 해양 분야에 적용을 위하여 해양 분야에서 요구하는 GNSS(Global Navigation Satellite System)에 대한 안전조건을 조사하고 이를 바탕으로 해양 분야에 사용가능한 감시 기법을 제시한다.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.9
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• pp.871-877
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• 2012

An error analysis of PPP (Precise Point Positioning) using IF (Ionosphere Free) combination is given in this paper. It is shown that the performance of the ordinary model with positions, clock bias, integer ambiguities and ionosphere delay as unknowns is equivalent to that of an ionosphere difference combination where ionosphere delay is cancelled out. Furthermore, it is shown that IF combination is an ionosphere difference combination but not unique. It is also proved that all difference models show same performances. The error analysis evaluated with a hardware simulator and real measurements show that the ionosphere delay is effectively eliminated by IF combination or equivalently by the ionosphere difference combination. However, if bias errors such as troposphere, clock bias or multipath are included in the measurements, the performance of the IF combination is degraded because the bias errors are amplified by the ionosphere difference operation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.754-758
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• 2017

In this paper, we designed and manufactured an automatic control system to minimize or avoid damage by automatically controlling ship engines in case of fog to allow for safer operation. This automatic power control system uses ATmega128 and an RPM detection circuit to measure RPM changes by artificially generating fog in the fog generator. For this purpose, we have created a complete schematic and applied our source code to an ATmega128 for PWM control using a Hall sensor motor. In future, an experiment and safety evaluation using this automatic power control system with an actual ship will be prepared.