• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.1
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• pp.40-46
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• 2015

Arctic Ocean has rapidly melted due to global warming, by this, commercial ship has been operating through the area. Reason to develop the Northern Sea Route(NSR) even in extreme conditions, the distance than the existing route is shortened, which bring economic benefits. For these reason, the International Maritime Organization(IMO) established safety standards of the Arctic navigation(Polar Code) in order to ensure safe operation in the Northern Sea Route. In this study, it has been described ice types and safety standards of Artic vessel what officer needs to know for safe navigation on the Arctic Ocean. And It was verified by simulation the theoretical knowledge for the safe operation of the Arctic vessel. As a result, it was found that ship needs to reduce speed and analyze ice for safe operation before enter into the ice, it is necessary to enter at right angle to break ice safety and efficiently. Also according to the result of the simulation of navigation entering in ice channel(Lead), it was difficult to change course, it is believed that require emergency training for passing Vessel. In the future, It shall be analyzed precisely under various conditions of scenario.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.1
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• pp.40-46
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• 2017

Shipping activities have become possible in the Arctic Ocean due to melting ice by global warming. An increasing number of vessels are passing through the Arctic Ocean consequently bringing concerns of ship-iceberg collisions. Thus, most classification societies have implemented regulations to determine requirements for ice strengthening in ship structures. This paper presents the simulation results of an ice-strengthened polar class ship after an iceberg collision. The ice-strengthened polar class ship was created in accordance with the Unified Requirements for a Polar-Ship (IACS URI). An elastic-perfect plastic ice model was adopted for this simulation with a spherical shape. A Tsai-Wu yield surface was also used for the ice model. Collision simulations were conducted under the commercial code LS-DYNA 971. Hull deformations on the ice-strengthened foreship structure and collision interaction forces have been analysed in this paper. A normal-strength ship structure in an iceberg collision was also simulated to present comparison results. Distinct differences in structural strength against ice impact forces were shown between the ice-strengthened and normal-strength ship structures in the simulation results. About 1.8 m depth of hull deformation was found on the normal ship, whereas 1.0 m depth of hull deformation was left on the ice-strengthened polar class ship.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.8-10
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• 2014

정부의 북극항로 시험운항이 시행된 2013년 NSR횡단 선박 척수는 전년도에 비해 54%가 늘어난 71척에 이르렀으나 실제 화물수송량은 당초 예상량인 150만톤에도 못 미치는 1,355,897톤으로 전년도에 비해 7.5% 증가에 그치고 말았다. 이는 2013년 하절기 북극해의 얼음이 2012년도에 비해 훨씬 적게 녹았기 때문으로 분석되고 있다. 그러나 지구온난화로 인한 전체적인 해빙 크기의 감소추세는 큰 틀에서 벗어나지 않고 있으므로 NSR의 선점을 위해서는 화물의 경제성 평가와 더불어 고효율선의 운항에 대비할 필요가 있다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.115-117
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• 2015

몇 년 전까지 북극해항로에 대한 각 국가의 관심이 증가하였다가 여러 가지 사유로 인해 최근에는 관심도가 많이 떨어졌다. 그러나 최근 러시아에서 북극해항로 개발 프로젝트 추진, 항해안전성 확보에 대한 노력 등의 적극적인 활동이 이루어지고 있다. 또한 Polar code 및 극지해역 운항선박의 승무원에 대한 교육의 강제화가 예상되고 있다. 본 연구에서는 향후 극지해역에서 선박운항을 하고자 하는 경우 선박회사에서 고려해야 할 사항에 대하여 다루고자 한다.

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.35-35
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• 2017

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1044-1048
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• 2015

Recently, the viability of the Northern Sea Route has been receiving a remarkable amount of attention. Owing to global warming, glaciers in the Arctic Ocean have been melting rapidly, which has opened up navigation routes for ships with commercial as well as research purposes. At present, vessels can be economically operated along the Northern Sea Route four months of the year. However, studies have shown that the economical operating time may increase to six months by 2020 and year-round by 2030. Even though the conditions of the Northern Sea Route are extreme, the main reason for its use is that the route is shorter than the existing route using the Suez Canal, which provides an economic benefit. In addition, 25% of the world's oil reserves and 30% of its natural gas are stored in the coastal areas of the East Siberian Arctic region. Many factors are leading to the expectation of commercial navigation using the Northern Sea Route in the near future. To satisfy future demand, the International Maritime Organization established the Polar Code in order to ensure navigation safety in polar waters; this is expected to enter into force on January 1, 2017. According to the code, a ship needs to reduce its speed and analyze the ice for safe operation before entering into it. It is necessary to enter an ice field at a right angle to break the ice safely and efficiently. This study examined the operation along the course for safe navigation of the passage under several conditions. The results will provide guidelines for traffic officers who will operate ships in the Arctic Ocean.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.170-172
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• 2018

지구 온난화로 인해 여름철 북극해의 해빙이 점차 감소함에 따라서 북극항로를 이용한 선박의 화물운송이 점차 증가하고 있다. IMO에서는 극지해역운항선박의 안전성과 해양오염방지를 위하여 2014년에 Polar Code를 개정하였으며, 2017년 1월부터 SOLAS협약과 MARPOL73/78협약에 추가되어 시행되고 있다. 본 연구는 해양수산부 해양안전 및 해양교통시설기술개발 사업으로 1) Polar Code 강제화에 따라 '극지해역 운항선박용 항해안전지원시스템의 개발'의 필요성과 2) 북극항로에 대한 국적선의 안전 운항 확보를 위한 '북극권 국가와의 국제협력 및 공조체계 구축'과 '극지 구난, 구조 및 환경보호 관련 국내법 및 규정 제정'을 위한 기반 연구의 필요성에 의거하여 2014년 11월 10일에 시작되었으며 2018년 12월 31일에 종료될 예정이다. 연구내용은 1) 고정밀도 북극항로 빙상정보 수치예측 시스템 개발, 2) 북극항로 안전속도 예측, 평가, DB구축 및 항행 모델 개발, 3) 북극항로 안전운항을 위한 항해계획 기술 개발, 4) 북극항로 운항선박 건조 및 안전항해 가이드라인 개발이다. 본 논문에서는 개발 중인 KRISO Arctic safe Routing System (KARS)에 대한 소개와 활용 결과 및 향후 계획에 대해서 설명하고자 한다. 본 KARS는 향후 지속적인 수정보완 작업을 통해서 완성도를 높여갈 예정이며, 검증단계를 거쳐서 최적하고 안전한 항로와 운항 관련 정보를 선사와 해기사에게 제공함으로서 북극항로 중 단기 운항계획 수립과 안전 운항을 지원할 수 있을 것으로 기대된다.

• Information and Communications Magazine
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• v.15 no.9
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• pp.97-106
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• 1998

It is crucial to predict the variabilities of the near-earth space environment associated with the solar activity, which cause enormous socio-economic impacts on mankind. The geomagnetic storm prediction scheme adopted in this study is designed to predict such variabilities in terms of the geomagnetic indices, AE and Dst, the cross-polar cap potential difference, the energy dissipation rate over the polar ionosphere and associated temperature increase in the thermosphere. The prediction code consists of two parts; prediction of the solar wind and interplanetary magnetic field based upon actual flare observations and estimation of various electrodynamic quantities mentioned above from the solar wind-magnetosphere coupling function 'epsilon' which is derivable through the predicted solar wind parameters. As a test run, the magnetic storm that occurred in early November, 1993, is simulated and the results are compared with the solar wind and the interplanetary magnetic field measured by the Japanese satellite, Geotail, and the geomagnetic indices obtained from ground magnetic observatories. Although numerous aspects of the code are to be further improved, the comparison between the simulated results and the actual measurements encourages us to use this prediction scheme as the first appoximation in forecasting the disturbances of the near-earth space environment associated with solar flares.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.3
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• pp.63-71
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• 1990

The hydrodynamic model parameters for the submicron GaAs simulation are calculated using the Monte Carlo method. $\Gamma$, L-, and X-valleys are included in the conduction band of GaAs, and polar optic phonon, acoustic phonon, equivalent intervalley, non-equivalent intervalley, ionized impurity, and piezoelectric scattering are taken into account. The velocity-electric field strength curve obtained in this paper is in good agreement with experimental one. We present the results in tabular form so that other participants can make use of them to simulate the submicron GaAs devices by the hydrodynamic model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.2
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• pp.658-675
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• 2022

This paper presents a fast-simplified successive cancellation (SC) flipping (Fast-SSC-Flip) decoding algorithm for polar code. Firstly, by researching the probability distribution of the number of error bits in a node caused by channel noise in simplified-SC (SSC) decoder, a measurement criterion of node reliability is proposed. Under the guidance of the criterion, the most unreliable nodes are firstly located, then the unreliable bits are selected for flipping, so as to realize Fast-SSC-Flip decoding algorithm based on node reliability (NR-Fast-SSC-Flip). Secondly, we extended the proposed NR-Fast-SSC-Flip to multiple node (NR-Fast-SSC-Flip-ω) by considering dynamic update to measure node reliability, where ω is the order of flip-nodes set. The extended algorithm can correct the error bits in multiple nodes, and get good performance at medium and high signal-to-noise (SNR) region. Simulation results show that the proposed NR-Fast-SSC-Flip decoder can obtain 0.27dB and 0.17dB gains, respectively, compared with the traditional Fast-SSC-Flip [14] and the newly proposed two-bit-flipping Fast-SSC (Fast-SSC-2Flip-E2) [18] under the same conditions. Compared with the newly proposed partitioned Fast-SSC-Flip (PA-Fast-SSC-Flip) (s=4) [18], the proposed NR-Fast-SSC-Flip-ω (ω=2) decoder can obtain about 0.21dB gain, and the FER performance exceeds the cyclic-redundancy-check (CRC) aided SC-list (CRC-SCL) decoder (L=4).