• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.6
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• pp.460-465
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• 2016

Long pipe structures are usually installed in fixtures located with regular intervals or laid underground. Therefore, deflection and deformation could easily occur due to their weight or ground activity. A shape monitoring technique can be used effectively to evaluate the integrity of the pipe structures. Fiber Bragg grating (FBG) sensors, which have an advantage of multiplexing could be used to measure strains at multiple-points of a long structure. In this study, to evaluate the integrity of a pipeline, a shape estimation technique based on strain information was proposed. Furthermore, different experiments were conducted to verify the performance of the proposed technique. Thus, the proposed shape estimation technique can represent the shape according to the deformation of the specimen using the FBGs. Moreover, calculated deflection of the pipeline using the estimation technique showed a good agreement with the actual deflection of the pipeline.

• Land and Housing Review
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• v.2 no.2
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• pp.183-188
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• 2011

Recently, the depth of tunnel constructed is getting deeper, which increases difficulty in construction works. Deliberate tunneling techniques are needed as the span and length of tunnels are increased. As one of the technical developments for tunnel, U-shaped and reinforced spider lattice girders are developed by optimizing the spider used in 95mm lattice girder as tunnel steel ribs. In order to evaluate the load bearing capacity of the lattice girder, the 4-point flexural tests are carried out. For the laboratory tests, straight specimens are made for the existing lattice girder and the new lattice girder. The results of the flexural tests showed that the maximum load bearing capacity of the new lattice girders was higher than the traditional one. The load-displacement behavior of the test specimens showed the elasto-plastic behavior in the existing lattice girder and the stress softening behavior in the new lattice girder. It was found that the load bearing capacities are changed depending on the location of the loading points.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.10
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• pp.48-56
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• 2002

A fabrication method of long--period fiber gratings (LPFGs) that can be easily controlled resonance wavelength and losses is introduced. We used the superposition method that core and cladding diameter are modulated by applying a number of small electric-arc to the normal fiber. We derived an equation of resonance wavelength change according to core diameter variation using the phase matching condition and showed the results are well matched with experiments. The measured resonant wavelengths of arc-induced superposition LPFGs according to grating period are well coincident with that of phase matching condition. The resonance wavelength is measured for the temperature changes and a slight mechanical strength degradation of arc-induced LPFGs is observed by increasing arc times.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.1
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• pp.61-69
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• 1999

To promote the usability of CFD techniques for the basic hull form design, a hull surface mesh generating program, based on given station offsets and centerline profile, is developed. The new method employs non-uniform parametric splines with predetermined waterline end-shapes of natural spline, normal spline, ellipse, parabola hyperbola, and their combinations. Generated hull surface meshes can be utilized for potential panel method immediately and can be also used as a boundary grid surface for 3-D field grid system. Mesh topology chosen to represent hull surface can be transformed into a rectangle, which he1ps the flow solvers to transform surface meshes for the nonlinear free surface condition or to define the turbulence quantities. To prove the applicability, a container ship with bow and stem bulb is chosen, and the procedures generating hull surface meshes are described.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.72-73
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• 1994

• 한국전자현미경학회:학술대회논문집
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• 1999.05a
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• pp.48-49
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• 1999

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.230-233
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• 1999

• Proceedings of the Korean Vacuum Society Conference
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• 2003.08a
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• pp.168-168
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• 2003

• Journal of Ocean Engineering and Technology
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• v.14 no.1
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• pp.11-16
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• 2000

수중날개를 대상으로 임의로 변형하는 이층류의 수직계산을 수행하였다. 계산은 비구조격자와 접면포착법을 이용하여 자유표면의 형상을 결정하였다 본 연구에 의하면 낮은 물속 깊이와 높은 프루드수에서 쇄파현상이 발생하였다 수중날개에 대하여 쇄파형상의 효과를 연구하였고 실험값과 계산값을 상호비교함으로서 격자의 민감성을 수직적으로 확인하였다.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.29.2-29
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• 2003