• 대한조선학회논문집
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• 제48권5호
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• pp.390-395
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• 2011

The main purpose of ice model basin is to assess and evaluate the performance of the Arctic ships and offshore structures because the full-scale tests in ice covered sea are usually very expensive and difficult. There are various ice conditions, such as level ice, brash ice, pack ice and ice ridge, in the real sea. To estimate their capacities in ice tank accurately, an appropriate model ice sheet and prepared ice conditions copied from actual sea ice conditions are needed. Pack ice is a floating ice that has been driven together into a single mass and a mixture of ice fragments of varying size and age that are squeezed together and cover the sea surface with little or no open water. So Ice-class vessels and Icebreaker are usually operated in pack ice conditions for the long time of her voyage. The most ice model tests include the pack ice test with the change of pack ice concentration. In this paper, the effect of pack ice size and channel breadth in pack ice model test is conducted and analyzed. Also we presented some techniques for the calculation of pack ice concentration in the model test. Finally, we developed a new model test methodology of pack ice condition in square type ice tank.

• 한국식품저장유통학회지
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• 제21권1호
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• pp.25-33
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• 2014

본 연구는 저장 중 참외(Cucumis melo var. makuwa)의 품질 개선 효과를 보기 위하여 일반 골판지 박스로 포장한 무처리 대조구, 아이스 팩을 첨가하여 포장한 시험구, 및 아이스 팩과 알루미늄 코팅 보드로 처리된 박스로 포장한 시험구를 각각 사용하여 실험을 수행하였다. 참외의 품질변화는 $30^{\circ}C$의 저장 조건에서 21일 동안 저장 기간에 따른 참외의 호흡률, 중량감소율, 색도, 경도, 당도, 외관 품질 및 부패과 발생율로 관찰하였다. 저장 21일째 아이스 팩을 첨가한 포장 그리고 아이스 팩 및 알루미늄 코팅 보드를 적용한 포장으로 저장한 참외는 호흡률, 중량감소율, 및 색도, 및 경도 값의 지연으로 뛰어난 선도 유지 효과를 나타냈을 뿐만 아니라 특히 외관품질, 부패과 발생율을 감소시켜 상품성이 유지 효과를 보았다. 반면 참외의 가용성 고형분 함량 값은 각각 다른 형태로 적용한 포장에 의해 큰 영향을 받지 않았다. 아이스 팩과 알루미늄 코팅 보드를 적용한 박스로 포장한 참외는 아이스 팩으로 만 포장한 참외 보다 상대적으로 품질이 개선되는 것을 확인 할 수 있었다. 골판지 박스 내부에 아이스 팩의 적용은 참외 과실이 품고 있는 온도를 낮출 뿐만 아니라 알루미늄 코팅 보드는 외부 고온 환경으로 부터 온도 차단 효과로 포장 내부의 온도 상승에 따른 빠른 품질 변화를 막을 수 있는 역할을 한다고 판단된다.

• 한국해양공학회지
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• 제32권3호
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• pp.184-191
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• 2018

Recently, as sea ice in the Arctic has been decreasing due to global warming, it has become easier to develop oil and gas resources buried in the Arctic region. As a result, Russia, the United States, and other Arctic coastal states are increasingly interested in the development of oil and gas resources, and the demand for offshore structures to support Arctic sea resources development is expected to significantly increase. Since offshore structures operating in Arctic regions need to secure safety against various drifting ice conditions, the concept of an ice-strengthened design is introduced here, with a priority on calculation of ice load. Although research on the estimation of ice load has been carried out all over the world, most ice-load studies have been limited to estimating the ice load of the icebreaker in a non-oblique state. Meanwhile, in the case of Arctic offshore structures, although it is also necessary to estimate the ice load according to oblique angles, the overall research on this topic is insufficient. In this paper, we suggest algorithms for calculating the ice load of managed ice (pack ice, 100% concentration) in an oblique state, and discuss validity. The effect of oblique angle according to estimated ice load with various oblique angles was also analyzed, along with the impact of ship speed and ice thickness on ice load.

• 한국해양공학회지
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• 제32권3호
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• pp.177-183
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• 2018

This study simulated ice load and the motion response of a moored semi-submersible rig in pack-ice conditions using a finite element method. Ice flows of random size and shape were modeled, and interactions for ice-sea, ice-structure, ice-ice were simulated using a simplified method. Parameters for the simplified method such as drag force coefficient and the pressure-penetration relation were obtained based on the result of detailed analysis using the coupled Eulerian-Lagrangian method. The mooring lines were modeled by spring elements based on their stiffness. As a result of the simulation over 1,400 seconds, the force and motion response of the rig were obtained and validated using discrete elements and compared with the results found by the Krylov State Research Centre.

• 대한조선학회지
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• 제53권2호
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• pp.18-22
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• 2016