• Journal of the Society of Naval Architects of Korea
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• v.45 no.2
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• pp.175-185
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• 2008

One of the concerns that arise during navigation in ice-covered waters is the magnitude of ice loads encountered by ships. However, the accurate estimation of ice loads still remains as a rather difficult task in the design of icebreaking vessels. This paper focuses on the development of simple ice load prediction formulas for the icebreaking cargo vessels. The maximum ice loads are expected from unbroken ice sheet and these loads are most likely to be concentrated at the bow area. Published ice load data for icebreaking vessels, from the model tests and also from full-scale sea trials, are collected and then several ice load prediction formulas are compared with these data. Finally, based on collected data, a semi-empirical ice load prediction formula is recommended for the icebreaking cargo vessels.

• Journal of Ocean Engineering and Technology
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• v.32 no.6
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• pp.458-465
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• 2018

Ice-going ships such as icebreakers, icebreaking tankers, and icebreaking LNG carriers are subjected to wave loads in open water and ice loads in ice-covered water. In terms of the ship's structural design, the local ice load is important. The fatigue failure due to repeated ice loads is also important. ISO 19906 specifies the assessment of the fatigue limit for a polar offshore structures. In addition, Lloyd's Register refers to fatigue damage based on ShipRight FDA ICE. In ShipRight FDA ICE, the fatigue damage indices due to wave and ice loads are simply presented as 0.5 for each load. It also states that the sum of the two fatigue damage indices should not exceed one. This study calculated and analyzed the fatigue damage index and fatigue life considering ARAON's voyage schedules and the assumed Antarctic voyage based on data measured during the Arctic voyage of ARAON in 2010.

• Journal of Ocean Engineering and Technology
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• v.35 no.5
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• pp.369-381
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• 2021

The International Ice Patrol (IIP) was established after the Titanic collided with an iceberg off the eastern coast of Canada in 1912 and sank, killing more than 1,500 people. Recently, the IIP has analyzed satellite images and provided safe operation information to vessels by tracking the occurrence and movement of icebergs. A large number of recent arctic studies mainly deal with sea ice formed by freezing seawater related to sea routes and resource development. The iceberg that collided with the Titanic was land-based ice that dislodged from a glacier and fell into the sea. The properties of these two types of ice are different. In addition, vessels operating in ice-covered waters such as the Arctic sea have an ice-breaking function or minimum ice-strengthened functions. Ships operating on transatlantic routes including the eastern coast of Canada do not necessarily require ice-strengthened functions. Hundreds to thousands of icebergs are discovered each year near the area where the Titanic sank. In this study, the status of ship-iceberg collision accidents was investigated to provide useful information to researchers, and the physical and mechanical characteristics of icebergs were investigated and summarized.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.4
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• pp.1031-1041
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• 2016

Interests in the Polar Regions have been growing due to various factors such as depletion of natural resources and advanced resource development technologies, accelerated rate of polar ice melting as a result of global warming, etc. In particular, demand for the workforce related to vessel passage using the Northern Sea Route and polar studies is still expanding. The International Maritime Organization adopted the Polar Code in 2015 for the safety of ship operation in polar waters and it will enter into force from 2017. But education and training section in the code has been prescribed only for the safe navigation in the ice covered waters intended for navigational offices. There is no basic safety training requirement that applies commonly for all personnel exposed to the risk of the polar regions and the relevant study or discussion has not been made so far. Therefore, this study provides basic data for developing safety training courses for crew and other personnel by analyzing relevant regulations on polar safety training and the contents of relevant safety training in offshore industry required by the costal states adjacent to arctic ocean.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.4
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• pp.306-312
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• 2018

To navigate in ice-covered waters, the ice-breaking process is required. The ice-breaking mode depends on material properties of sea ice and ice conditions. The ice-breaking mode is classified into ramming and continuous ice-breaking. The ramming is effective on large ice features, such as thick ice ridge and icebergs, and the continuous ice-breaking is on level ice. In general, the impact time duration of crushing or bending on ice sheets is from 0.2 to 1.0 second. However, impact duration in ramming will be increased. The Korean ice-breaking research vessel ARAON conducted her research voyage in the Antarctic sea during the winter of 2012. The IBRV ARAON measured strain in ramming and continuous ice-breaking. Strain gauge signals were recorded during the planned ice-breaking performance and the unplanned ice transits in heavy ice conditions. The aim of this study is to investigate the ice load signals measured in ramming processes under the heavy ice condition. Based on the time history of the signals, a raising time, a half-decaying time and time duration were investigated and compared with the previous study which was suggested the five profiles of the ice load signals.

• Journal of Ocean Engineering and Technology
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• v.34 no.6
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• pp.394-405
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• 2020

To assess the station-keeping performance of floating structures in the Arctic region, the ice load should be considered along with other environmental loads induced by waves, wind, and currents. However, present methods for performance evaluation in the time domain are not effective in terms of time and cost. An ice load generation module is proposed based on the experimental data measured at the KRISO ice model basin. The developed module was applied to a time domain simulation. Using the results of a captive model test conducted in multiple directions, the statistical characteristics of ice loads were analyzed and processed so that an ice load corresponding to an arbitrary angle of the structure could be generated. The developed module is connected to commercial dynamic analysis software (OrcaFlex) as an external force input. Station-keeping simulation in the time domain was conducted for the same floating structure used in the model test. The mooring system was modeled and included to reflect the designed operation scenario. Simulation results show the effectiveness of the proposed ice generation module and its application to station-keeping performance evaluation. Considering the generated ice load, the designed structure can maintain a heading angle relative to ice up to 4°. Station-keeping performance is enhanced as the heading angle conforms to the drift direction. It is expected that the developed module will be used as a platform to verify station-keeping algorithms for Arctic floating structures with a dynamic positioning system.

• Journal of Navigation and Port Research
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• v.37 no.2
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• pp.143-148
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• 2013

The aim of this study is to investigate the characteristics on the profile of local ice load acting on side shell of port side in bow part due to broken ice during icebreaking of ships in ice covered waters. The first Korean icebreaking research vessel 'ARAON' had a sea ice field trial in the Arctic Sea during early August, 2010, and the signals due to local ice impact measured from several strain gauges installed at bow part were gathered. It is known that these data with structural response characteristics due to local ice impact have some different characteristics with a typical hydraulic impact pressure - time history. In this study, the time history on the measured signals was analyzed and the characteristic values were presented using non-dimensional parameters.

• Journal of Ocean Engineering and Technology
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• v.33 no.5
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• pp.411-420
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• 2019

It is essential to design crashworthy marine structures for operations in Arctic regions, especially ice-covered waters, where the structures must have sufficient capacity to resist iceberg impact. In this study, a numerical analysis of a colliding accident between an iceberg and stiffened plates was carried out employing the commercial finite element code ABAQUS/Explicit. The ice material model developed by Liu et al. (2011) was implemented in the simulations, and its availability was verified by performing some numerical simulations. The influence of the ambient temperature on the structural resistance was evaluated while the local stress, plastic strain, and strain energy density in the structure members were addressed. The present study revealed the risk of fracture in terms of steel embrittlement induced by ambient temperature. As a result, the need to consider the possibility of brittle failure in a plate-stiffener junction during operations in Arctic regions is acknowledged. Further experimental work to understand the structural behavior in a plate-stiffener junction and HAZ is required.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.237-239
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• 2011

최근 국제해사기구(International Maritime Organization, IMO)는 "극지를 운항하는 선박에 대한 안전기준(Polar Code)"를 제정하여 결정하기로 하였으며, 2012년까지 완료하여 법제화하기로 하였다. 이는 최근의 극해 지역의 연속적인 사고의 심각성에 대한 대비책의 일환이다. 2004년도에 알라스카 앞바다에 침몰한 Selendang Ayu 는 6600만 톤의 콩, 170만 리터의 연료유와 55,564 리터의 MDO 및 다른 오염물질을 바다에 유출하였다. 이는 주변의 동물들에게 심각한 영향을 끼쳤고, 아직까지도 유출되어진 오염물질들을 완전히 처리하지 못한 상태이다(Arctic marine shipping assessment, Arctic council 2009.). 즉, 기름이 유출을 하면 방재시설이 다른 육상에서 오기 전까지는 상당히 오랜 시간 동안, 사고 지역 주변을 오염시키게 되며, 유빙이나 극한의 온도는 방재 작업을 더욱 힘들게 한다. 본 연구에서는 극해와 같은 해역에서 기름이 유출 하였을 때에 대응하는 방법, 즉 현존하는 기계적인 복구 방식, 점화식 처리 방식 과 유처리제 방식을 소개하고, 그에 대한 국제규정 및 기술 발전 동향에 대해서도 설명한다.