• Journal of Navigation and Port Research
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• v.29 no.1 s.97
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• pp.23-28
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• 2005

The signal in wireless multi-path channel is affected by fading and ISI because of high data rate transmission, so the signal has the high error rate. The present modulation and demodulation method of DSRC system can not expect sufficient for providing data service over 1 Mbps, so the channel equalization and advanced modulation and demodulation methods are required. OFDM is generally known as an effective technique for high data rate transmission system, since it can prevent ISI by inserting a guard interval. However, a guard interval longer than channel delay spread has to be used in each OFDM symbol period, thus resulting a considerable loss in the efficiency of channel utilization Therefore the equalizer is necessary to cancel ISI to accommodate advanced ITS service with higher bit rate and longer channel delay spread condition In this paper, the channel equalizer for the OFDM -DSRC system was designed and its performance in a multi-path fading environment was evaluated with computer simulation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.169-174
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• 2004

To design ship channel is one of important factors for planning and developing a port. In most case, the core factors for designing ship channel are the layout and width of dvnnel provided the net underkeel clearance is assessed as safety. In this study, Variable Bumper Area(VBA) model is applied to design and assess ship channel. This model reflects ship's principle dimension, ship domain theory, ship speed, conning officer's ship handling skill and experience and all external forces which cause leeway, set and drift and the change of ship maneuvering characteristics. Full Mission Ship Handling Simulator is used to analyze ship dynamic data according to conning officer's ship control, external forces, etc. This model uses Domain-index for assessing the efficiency and safety of the channel. The proposed model is applied to Ulsan new port plan which has a channel width of 1.5 times the length if the largest vessel, a radius if 5 times the length of the largest vessel in a curve of 57 degree centerline angle and SBM facility adjacent to the lateral edge if channel. The result of this study shows tint the width and radius of channel curve are suitable for the target ship but the difficulty of ship handling is caused by the large course change and SBM located in the vicinity if channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1450-1456
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• 2015

The received signal strengths according to the propagation distance between a transmitting shore station with a 53 m antenna hight and a receiving ship station with about 6m antenna hight from 700 m upto about 20 km are measured at ship's moving velocity of $5{\pm}1m/s$ using a single carrier signal at 150.0625MHz. In this paper, the path loss exponents at the propagation distance from 700 m to 20km are estimated via minimum-mean-square-error method using the measurements of the received signal strength, and the mean of the estimated path loss exponent become 3.79. The estimated propagation path loss exponents is similar to that calculated based on the field-strength values from 2 km to 20 km in Annex 2 of ITU-R P.1546-4, which is measuring results at maritime VHF at 100 MHz carrier frequency. Therefore, the estimated propagation path loss exponent shall be used as the expected path loss exponents for summer in costal area of South Sea of Korea.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.811-814
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• 2009

The HF band maritime communication is have developing to digital methode that techniques should be readied the automatic link establishment of 1:N by coast station to many ship station. Because can use way by polling simply that communication environment calls particular station wicked fellow HF communication states which is much redundancy times for coast station to set link. In amateur radio particular station selective calling do to be using ALE(Automatic Link Establishment) controller by 1:1 automatic link setting way, but expect 1:N link setting by these way in maritime communication very difficult. That is difficult to avoid collision by traffic overload to induce calling of ship stations. Because HF communication considers channel special quality traffic state radio link should be established, and should be applied automatically secures stability of channel as accommodative at traffic overload. In this paper is studied the new radio protocol by 3 step sequency driving of free access, group free access and polling access using multi-tone in single channel.

• The Journal of Fisheries Business Administration
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• v.54 no.3
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• pp.29-43
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• 2023

The United States is Korea's important trading partner, ranking third (13.7%) in exports of fishery products in Korea. The impact on exports to the United States is expected to be significant if the seafood import provisions under the MMPA are implemented in 2024 accordingly. It is expected that documents proving production information will be required for all items when exporting to the U.S. Therefore, this study attempted to examine the current status of exports and exporters in order to understand the actual conditions of major fishery products exported to the United States. Besides, there are currently no official system and procedures in Korea to prove production information for all fishery items, so we tried to suggest implications by examining distribution channels for major export items to the U.S. In this study, five items including seaweed and halibut as domestic aquaculture items, tuna and squid as deep-sea fishing items, and fish cake using imported raw materials were selected as the target items for distribution channel investigation. In addition, this study is meaningful in that it investigated the routes from production to processing, distribution, and export of each item and identified detailed distribution channel for major items exported to the U.S.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.67-73
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• 2003

In these days, several bridges have been built or under construction over navigational channel in Korea In these cases there must be careful consideration for the marine safety of vessels to be passed by below the bridge. This paper aims to analyze the factors influencing maritime traffic safety and to figure out ample width of main span of these kinds of bridges through the reference study and FMSS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1405-1412
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• 2015

Recently, Due to the rapid growth of broadcasting communication and video coding technologies, the demands for immersive media contents based on 3D stereoscopic video will increase steadily. And the demands must ultimately provide the contents for users which are in wireless channel such as vehicle, train, and ship. Thus, in this paper, we transmit the 3D stereoscopic video over the maritime Rician channel that direct wave is more dominant than reflective wave. Besides, we present unequel error protection (UEP) by applying hierarchical 4/16-QAM to V+D(Video plus Depth) format which can represent 3D stereoscopic video. We expect our system to provide seamless broadcasting service for users with poor reception condition.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.187-192
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• 2015

Underwater acoustic communication channels have very complex channel characteristics caused by time-varying sea surface, submarine topography, sound speed, and geometry between transmitter and receiver. Especially, the channel has time-variance and doppler effect due to wind and sea current. We have to recognize the channel state and apply it to communication technique for increasing transmission efficiency in the underwater acoustic channel. In this paper, we present the frame recursive modulation and demodulation method using ambiguity function and autocorrelation function to estimate the doppler frequency. Furthermore, we conducted the simulation and sea experiment to evaluate the performance of the proposed method. When the channel coding technique was not used, the bit error rate performance of the proposed method was improved about 32 % compared with conventional method.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1303-1306
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• 2009

수중에서의 통신은 해수면과 해저면 등에 의한 신호의 반사에 의해 발생한 다중경로 현상으로 신호가 왜곡되어 원활한 통신이 어렵다. 이에 본 논문에서는 다중경로에 의해 발생한 오류를 정정하고자 수중 채널 전달함수를 이용한 정정기법을 제안하였으며, 시뮬레이션 결과 제안한 기법을 적용하였을 경우 적용하지 않았을 때 보다 더욱 우수한 성능을 보이는 것을 확인 할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1281-1284
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• 2009

무선통신에서는 다양한 서비스, 높은 신뢰도와 함께 빠른 전송속도를 요구한다. 이러한 요구를 만족시키기 위해서 LDPC 부호와 MIMO 기술이 활발히 연구 중에 있다. 본 논문에서는 LDPC와 결합된 STC 모델을 설명하고, 여러개의 송신안테나로부터 송신되어 결합된 신호를 분리하기 위해 사용되는 Log-Likelihood Computation을 기존의 방식과 제안하는 저 계산량 알고리즘을 통한 방식을 비교, 분석하여 기존의 방식과 근접한 BER 성능을 유지 하면서 계산량 감소를 확인한다.