• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.11a
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• pp.107-112
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• 2002

Basically, ship structure consists of the plate members, and a strength of overall ship structurnds on the stiffness and strength of ship platings. If buckling which causes to deflect ship plate members occurs, the stiffness of ship plate markedly decreases, and thus buckling has a serious effect on the stiffness or strength of overall ship structure. Buckling is one of the most important design criteria when we scantle structure members. In the present study, a inplane rigidity of a compressed ship plate above buckling load is proposed. The proposed inplane rigidity is available in the elastic or elasto-Plastic ranges in order to can out a more efficient and reliable design.

• Korean Journal of Crystallography
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• v.13 no.2
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• pp.69-72
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• 2002

The interlaminar problems near the free edge of composite laminates are analyzed in this paper. CFRP specimen (［+40/-40］s) and interleaved specimen (［+40//-40］s) with non-woven carbon tissue (NWCT) are discussed under tensile loading condition. The symbol “//”means that the NWCT is located between the CFRP interfaces. The NWCT has carbon short fibers which are discretely distributed with the in-plane random orientation. It was reported/sup 3)/ that the Mode Ⅱ interlaminar fracture toughness of CFRP laminates with NWCT is increased largely and the Mode I interlaminar fracture toughness is not changed significantly. Mode Ⅲ interlaminar fracture toughness is also an important factor in composite structures. But it is not easy to experimentally investigate the Mode Ⅲ interlaminar fracture toughness. The objective of this work is to study the effect of the NWCT and to fundamentally understand the Mode Ⅲ interlaminar shear characteristics of laminated composites with NWCT in the vicinity of a free edge by using finite element method analysis.

• Composites Research
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• v.24 no.4
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• pp.29-35
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• 2011

The characteristic length method used to determine a laminate's strength generally requires the test for un-notched and notched laminates and finite element analysis together. In this paper, the methods used to predict the stress distribution and tensile characteristic length of open-hole laminates using the stress concentration factor and equivalent material properties are proposed. These methods do not require data on the failure load of open-hole laminates or finite element analysis. Once the stress and characteristic length have been determined, the failure load of the open-hole laminate can be calculated. The proposed method considers the effect of the material properties as a parameter and therefore can be applied to a variety of materials. The stress distribution is verified by comparing with a finite element analysis and test results. The predicted failure load shows a maximum deviation of 8% from the test results.

• Journal of the Korean Vacuum Society
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• v.12 no.4
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• pp.281-287
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• 2003

We have performed classical molecular dynamics simulations for hypothetical silicon nanotubes using the Tersoff potential. Our investigation presented a systematic study about the thermal behavior of hypothetical silicon nanotubes and showed the difficulty in Producing silicon nanotubes or graphitelike sheets. Through the investigations on the structure and properties of a double-wall silicon nanotube, we concluded that quasi-one dimensional structures consisting of silicon atoms become nanowires or multi wall nanotubes rather than single wall nanotubes in order to minimize the number of $sp^2$ bonds.

• Korean Journal of Crystallography
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• v.9 no.2
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• pp.125-130
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• 1998

본 논문에서는 부직포를 삽입한 Gr/Ep 복합재료의 충격 흡수 특성을 연구하였다. 계면(interface) 층에 유리 부직포 또는 탄소 부직포를 삽입하여 복합적층판을 제작하였다. 저속충격 시험을 수행하였으며, 충격에 의한 층간분리(delamination)를 C-Scan과 현미경을 사용하여 관찰하였다. 실험결과 계면에 부직포를 삽입함으로써 충격에 의한 층간분리 면적이 감소함을 알 수 있었다.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.1
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• pp.49-56
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• 2020

Epoxy/carbon composite was used to prepare a bipolar plate for polymer electrolyte membrane fuel cell (PEMFC). Phenol novolac-type epoxy and diglycidyl ether of bisphenol A (DGEBA)-type epoxy mixture was used as a matrix and graphite powder, carbon fiber (CF) and graphite fiber (GF) were used as carbon materials. In order to improve the mechanical properties of the bipolar plate, surface-modified CF was incorporated into the epoxy/carbon composite. To determine the cure temperature of the epoxy mixture, differential scanning calorimetry (DSC) analysis was performed and the data were introduced to Kissinger equation in order to get reaction activation energy and pre-exponential factor. Tensile and flexural strength was obtained by using universal testing machine (UTM). The surface morphology of the fractured specimen and the interfacial morphology between epoxy matrix and CF or GF were observed by a scanning electron microscopy (SEM).

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.89-96
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• 2008

The purpose of this study is to investigate the flexural strengthening effectiveness for the beams reinforced with NSM CFRP strips. To accomplish this objective, concrete T beams were made and tested. From this study, it is found that the flexural stiffness and strength of the beams reinforced with NSM strips were significantly improved compared to the beams without CFRP strip. The maximum increase of flexural strength was 247%. Failure of the beam reinforced with NSM was initiated by a part of separation of NSM strips along the longitudinal direction, and the second failure of strips was investigated. After the first rupture of the NSM strips, the load dropped suddenly and the second rupture was succeeded. This result shows that a perfect composite reaction with NSM strips and concrete is possible in the beam reinforced with NSM CFRP strips the NSM strips and Near surface mounted(NSM) is one of the most recent and promising strengthening techniques for reinforced concrete structures.

• Journal of Navigation and Port Research
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• v.29 no.6 s.102
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• pp.515-522
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• 2005

The ship plating is generally subjected to. combined in-plane load and lateral pressure loads, In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion of the vessel. Lateral pressure is due to. water pressure and cargo. These load components are nat always applied simultaneously, but mare than one can normally exist and interact. Hence, far mare rational and safe design of ship structures, it is af crucial importance to. better understand the interaction relationship af the buckling and ultimate strength far ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except far the impact load due to. slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to. the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.61-67
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• 2005

The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull ginder bending and torsion of the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact. Hence, for more rational and safe design of ship structures, it is of crucial importance to better understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are inverstigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.147-154
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• 2005

The ship plating is generally subjected to combined in-plane load and lateral pressure loads. In-plane loads include axial load and edge shear, which are mainly induced by overall hull girder bending and torsion of the vessel. Lateral pressure is due to water pressure and cargo. These load components are not always applied simultaneously, but more than one can normally exist and interact Hence, for more rational and safe design of ship structures, it is of crucial importance to better understand the interaction relationship of the buckling and ultimate strength for ship plating under combined loads. Actual ship plates are subjected to relatively small water pressure except for the impact load due to slamming and panting etc. The present paper describes an accurate and fast procedure for analyzing the elastic-plastic large deflection behavior up to the ultimate limit state of ship plates under combined loads. In this paper, the ultimate strength characteristics of plates under axial compressive loads and lateral pressure loads are investigated through ANSYS elastic-plastic large deflection finite element analysis with varying lateral pressure load level.