• International Journal of Naval Architecture and Ocean Engineering
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• 제9권4호
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• pp.373-381
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• 2017

A Collaborative Optimization (CO) methodology for ring-stiffened composite material pressure hull of underwater vehicle is proposed. Structural stability and material strength are both examined. Lamination parameters of laminated plates are introduced to improve the optimization efficiency. Approximation models are established based on the Ellipsoidal Basis Function (EBF) neural network to replace the finite element analysis in layout optimizers. On the basis of a two-level optimization, the simultaneous structure material collaborative optimization for the pressure vessel is implemented. The optimal configuration of metal liner and frames and composite material is obtained with the comprehensive consideration of structure and material performances. The weight of the composite pressure hull decreases by 30.3% after optimization and the validation is carried out. Collaborative optimization based on the lamination parameters can optimize the composite pressure hull effectively, as well as provide a solution for low efficiency and non-convergence of direct optimization with design variables.

• 수산해양기술연구
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• 제55권2호
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• pp.145-151
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• 2019

The coastal composite fishery has the highest rate of around 30.0% in registered fishing vessels of Korea for the last three years. The risk analysis for the fisher's safety of coastal composite fishing vessels was conducted to serve as a basic data for improving the healthy and safe working environment of fisher using fisher's occupational accidents of the national federation of fisheries cooperatives (NFFC) from 2016 to 2018 (n = 1,105). As a result, the occupational accident occurrence rate of coastal composite fishery was 3.76% in all industries, 7.8 times the rate of that. In addition, death and missing rate was found to have a serious level management to 10.10‱. Among the accidents, 76.0% occurred at sea. The slipping, others and contact with machinery or fishing gear occurred more frequently in order in the frequency of accident occurrence pattern. In the risk assessment using frequency and severity, slipping, contact with machinery and others showed high risk during fishing. The results are expected to contribute to identification and assessment of safety hazard occurred in coastal composite fishing vessels.

• 항공우주시스템공학회지
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• 제17권6호
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• pp.127-132
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• 2023

본 연구에서는 필라멘트 와인딩 공법을 적용한 Type 4 압력용기의 설계를 수행하였다. 수소저장용 탱크의 설계인 점을 고려하여 누설을 방지하기 위해 라이너는 고분자 고밀도 폴리에틸렌(HDPE)을 적용하였고 복합재 구조는 카본/에폭시를 Hoop 방향과 Helical 방향으로 적층하여 설계하였다. 이론적 접근으로 Helical 섬유의 각도와 Hoop, Helical 각각의 섬유 두께를 결정하여 설계하였다. 설계에 대한 안전성은 상용소프트웨어인 ANSYS를 활용하여 유한요소 해석으로 검증하였다.

• 비파괴검사학회지
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• 제23권5호
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• pp.439-444
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• 2003

구조물이 하중을 받았을 때 손상부에서 발생하는 탄성파인 AE는 이를 탐지함으로써 손상부의 위치를 측정하는데 매우 효과적이다. 그러나 복합재료 구조에서의 위치표정은 탄성파의 전파속도가 섬유의 방향에 의존하는 이방성의 문제로 인하여 전통적인 방법을 그대로 적용할 경우 알고 있는 위치에 대해서도 정확도가 매우 낮으며, 미지의 발생윈을 찾는 것은 거의 불가능하다. 본 연구에서는 최근에 새로이 개발된 바 있는 이방성을 고려한 위치표정 방법이 실제 복합재 구조물에 적용될 경우에도 정밀도와 정확도 면에서 실용적인 방법임을 입증하고자 하였다. 기하학적으로 복잡한 구조체인 복합재 압력용기가 비어있을 경우와 물을 가득 채운 경우에 대하여 $0^{\circ}$(축방향)에서 $90^{\circ}$(원주방향)까지 모든 방향별 속도를 고려한 위치표정을 성공적으로 수행하였다.

• Composites Research
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• 제20권2호
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• pp.1-9
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• 2007

카본 에폭시로 제작된 복합재 압력용기의 노화 특성과 구조 사용 수명 평가를 위해 실내와 실외에서 10년과 15년간 자연노화 시켰다. 노화 특성의 통계적 분포를 구하기 위해 노화된 압력용기로부터 링 시편을 채취하여 수압 파괴 시험을 실시하였다. 그리고 섬유와 수지 계면의 노화 특성 확인을 위해 시험 파편 계면을 SEM을 이용하여 관찰하였다. 섬유 인장 파손 변형률의 와이블 파라미터 값 기준으로 실내에서 10년, 15년 노화되었을 경우 각각 19%와 23% 저하되었으나, 실내와 실외의 노화 특성 차이는 크지 않았다. 그러나 압력용기 외면에 적용한 표면 페인트는 노화 방지에 큰 효과를 나타내었다.

• International Journal of Ocean System Engineering
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• 제3권3호
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• pp.136-141
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• 2013

The present research was aimed at comparing performance of metallic and polymer composite shells of a typical underwater vessel of length and inner diameter of 1650 mm and 350 mm respectively, based on the critical buckling pressure for operating depth of 1000 m using ANSYS. High strength steel, aluminium alloy, titanium alloy, glass / epoxy and carbon / epoxy materials were examined. The results indicated weight savings of 46 % in carbon/epoxy and 31 % in glass / epoxy when compared with high strength steel, based on the thickness of the shell for sustaining 10 MPa buckling pressure.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.92-97
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• 2000

저속 충격을 받은 복합재로 만들어진 두꺼운 압력용기의 파괴모드와 손상 상태에 대하여 조사하여 이를 정량적으로 나타내는 것이 본 연구의 관심이다. 본 논문에 사용된 시편은 압력용기의 중앙을 길이 305mm로 잘른 원통형 ring모양이다. 충격자는 직경이 25.4mm와 12.7mm인 반구형 2종류와 모서리의 직경이 1mm인 원추형 1종류로 무게는 3.9kg이며 자유낙하 높이는 20mm에서 200mm로 종류에 따라 간격을 달리했다. 실험 장치로는 실린더가 충격에 흔들리지 않도록 고정하는 받침대와 자유낙하 하는 impactor 이며 impactor의 윗면에 한 개의 가속도 게이지를 설치했으며 밑면에 90도 간격으로 4군에 스트레인 게이지를 붙여 충격에너지, 최대 충격력, contact radius를 측정하고 시험후 시편은 방사선 촬영을 하여 충격자의 종류에 따라 손상의 정도가 어떻게 다른지를 파악했다. Herzian이론을 사용하여 contact radius를 구하고 측정된 자료와 비교 검토하였다. Contact radius 값은 충격자의 직경이 클수록 큰 것을 알수 있고 실험치 값은 이론치 값 보다 큰데 이는 실제 연소관의 기계적 성질의 값이 계산치 보다 적은 것이 원인이다. 직경이 25.4mm인 반구형의 충격자는 직경이 12.7mm인 반구형의 충격자에 비하여 내부에 delamination크기가 컸다. 가속도의 값은 높이에 따라 선형적으로 변하고 충격자의 모양이 둔탁할수록 가속도 값이 커지는 것을 알 수 있다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 Asia Navigation Conference
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• pp.208-216
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• 2004

Since 2000, the authors have been developing remote radar network system to observe the vessel traffic in Tokyo Bay. In December 2002, the first operational remote radar station was set at the National Defense Academy in Yokosuka, and vessel traffic observation was started. However, it was impossible to perform accurate observation in the northern part of Tokyo Bay by this Yokosuka radar station only. In September 2003, the second remote radar station and AIS receiving station were installed at Higashi Ogishima in Kawasaki. This second radar enabled us to carry out accurate observation in that area. Both radars can be remotely controlled from the monitoring station in Tokyo University of Marine Science and Technology. On September 30 and October 1,2003, the vessel traffic observation was carried out using both radars. Combining radar images observed by both radars, the ships' tracks were taken and the dangerous ships were extracted by using SJ value and Bumper Model. The time changes of dangerous ship density in some areas in Tokyo Bay and utilization ratio of the traffic routes were also investigated. In addition, analyzing the AIS date received at Kawasaki station, the positions and speed vectors of the ships equipped with AIS were shown.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권2호
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• pp.140-147
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• 2012

Microvascular reconstruction, in the oral and maxillofacial regions, is a widely accepted as the best way to overcome the complex oral cavity defects. Many patients requiring composite reconstructions have been treated previously with radiation therapy, chemotherapy, selective and/or functional neck dissection or any of these combinations. In many cases of these patients, inadequate neck vessels for the microanastomosis of free flap are available, due to a lack of recipient vessels in the neck, poor vessel quality or vessel caliber mismatch. To achieve a tension-free anastomosis, vein grafting must be considered to span the vessel gap between the free flap pedicle and the recipient neck vessels. Although most microsurgeons believed that interpositional grafts are to be avoided due to vessel thrombosis and increased number of necessary microanastomosis, we, authors have some confidence of equivalency between reconstruction with and without interpositional saphenous vein graft. The great saphenous vein, also known as the long saphenous vein, is the large subcutaneous superficial vein of the leg and thigh. It joins with the femoral vein in the region of femoral triangle at the saphenofemoral junction, and coursed medially to lie on the anterior surface of the thigh before entering an opening in the fascia lata, called the saphenous opening. For a better understanding of the great saphenous vein graft for the interpositional vessel graft in the oral cavity reconstructions, and an avoidance of any uneventful complications during these procedures, the related surgical anatomies with their harvesting tips are summarized in this review article in the Korean language.

• 한국항해학회지
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• 제15권1호
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• pp.67-93
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• 1991

In general, marine casualities take palace by the composite action of three elements such as waterway condition, vessel condition and man condition. One of the important characteristics of most marie casualties for small cargo vessels in maritime transportation of near-coastal and greater-coasting seas in that the same kind of casualities take place repeatedly in spite of the apprent causes, Because, it takes much time and effort for seamen to master waterway, vessel or operatin technique only to the practical and sensible level. In these days, with the development of our economy, our shiypping industry has grown and therefore the demand of marine officers has increased. This economic growth brought about undesirable situation like the evasion of seamen and frequent casualities of Korea vessels. These marine casualities are being caused mainly by the unskilfulness of operating technique as well as the bad waterway condition and ship's installation condition. Therefore, I conclude, in this paper, that the most efficient and economic preventing measures of marine casualities are seeking causes and removing them in advance under the close coperation system among all concerned parties.