• Smart Structures and Systems
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• 제24권6호
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• pp.803-812
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• 2019

Triplex composite is an epoxy-bonded joint structure, which constitutes the secondary barrier in a liquefied natural gas (LNG) carrier. Defects in the triplex composite weaken its shear strength and may cause leakage of the LNG, thus compromising the structural integrity of the LNG carrier. This paper proposes an autonomous triplex composite inspection (ATCI) system for visualizing and classifying hidden defects in the triplex composite installed inside an LNG carrier. First, heat energy is generated on the surface of the triplex composite using halogen lamps, and the corresponding heat response is measured by an infrared (IR) camera. Next, the region of interest (ROI) is traced and noise components are removed to minimize false indications of defects. After a defect is identified, it is classified as internal void or uncured adhesive and its size and shape are quantified and visualized, respectively. The proposed ATCI system allows the fully automated and contactless detection, classification, and quantification of hidden defects inside the triplex composite. The effectiveness of the proposed ATCI system is validated using the data obtained from actual triplex composite installed in an LNG carrier membrane system.

• Composites Research
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• 제24권3호
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• pp.39-45
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• 2011

접착제에 의한 접합은 일반적으로 구조물의 접합에 널리 사용되고 있다. 폴리우레탄 접착제와 에폭시 접착제는 현재 극저온에서 운항되고 있는 LNG 선박의 화물창에 적용되고 있다. 본 연구에서는 화물창용 소재인 트리플엑스와 폴리우레탄 및 에폭시 접착제와의 상온과 극저온에서의 접착강도를 평가하였다. 연구결과 모든 접착시스템에서 극저온에서 박리강도의 감소가 있었으며 그 원인은 접착제마다 다르게 검토되었다. 결과적으로는 폴리우레탄 접착제와 트리플엑스가 극저온에서의 강도 값이 에폭시에 비해 우수하였으며 LNG 선과 같은 극저온 환경에 접합한 것으로 평가되었다.

• 한국세라믹학회지
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• 제51권5호
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• pp.453-458
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• 2014

SiC and its composites have been considered for use as nuclear fuel cladding materials of pressurized light water reactors. In this study, a $SiC_f$/SiC composite as a constituent layer of SiC triplex fuel cladding was fabricated using a chemical vapor infiltration (CVI) process in which tubular SiC fiber preforms were prepared using a filament winding method. To enhance the matrix density of the composite layer, winding patterns, deposition temperature, and gas input ratio were controlled. Fiber arrangement and porosity were the main parameters influencing densification behaviors. Final density of the composites decreased as the SiC fiber volume fraction increased. The CVI process was optimized to densify the tubular preforms with high fiber volume fraction at a high $H_2$/MTS ratio of 20 at $1000^{\circ}C$; in this process, surface canning of the composites was effectively retarded.

• Composites Research
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• 제22권2호
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• pp.14-17
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• 2009

접착제에 의한 접합기술은 다양한 목적과 환경에서 널리 사용되는 방법이다. 그 중 우레탄 접착제는 액화천연가스 운반선과 같이 극저온에서 사용되는 환경에서의 접착에 사용되고 있다. 현장 적용에 있어, 본 접착제를 사용시 경화된 접착제 층의 기공들이 발생하게 된다. 본 연구에서는 우레탄 접착제와 Triplex 복합재료 접착에 있어 인공적으로 기공을 제작 삽입 후 전단응력 (Single Lap Shear) 시험을 실시하여 그 영향을 검토하였다. 실험 결과 접착력은 본 시험에서 적용한 기공의 크기 및 위치에 영향을 받지 않는다는 것을 확인하였다.

• 대한조선학회논문집
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• 제58권4호
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• pp.262-270
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• 2021

Consumption of Liquefied Natural Gas (LNG) has increased due to environmental pollution; therefore, the need for LNG carriers can efficiently transport large quantities of LNG, is increased. In various types of LNG Cargo Containment System (CCS), Membrane-type MARK-III composed of composite materials is generally employed in the construction of an LNG carrier. Among composite materials in a Mark-III system, glass-fiber composites act as a secondary barrier to prevent the inner hull structure from leakage of LNG when the primary barrier is damaged. Nevertheless, several cases of damage to the secondary barriers have been reported and if damage occurs, LNG can flow into the inner hull structure, causing a brittle fracture. To prevent those problems, this study conducted the applicability assessment of composite material manufactured by bonding glass-fiber and aluminum with epoxy resin and increasing layer from three-ply (triplex) to five-ply (pentaplex). Tensile tests were performed in five temperature points (25, -20, -70, -120, and -170℃) considering temperature gradient in CCS. Scanning Electron Microscopy (SEM) and Coefficient of Thermal Expansion (CTE) analyses were carried out to evaluate the microstructure and thermos-mechanical properties of the pentaplex. The results showed epoxy resin and increasing layer number contributed to improving the mechanical properties over the whole temperature range.