• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1604-1612
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• 2009

This study introduces comparison the testing results of the AL car body which is applied to FSW and GMAW welding method. The car body is made of aluminum structure materials like a sandwich panel. The static load test was performed to evaluate the structural characteristic and stability of the AL car body. Considering the vertical, compressive, twisting load and 3-point supporting, Bend natural frequency Measurement, Twist natural frequency Measurement type as a testing terms, the structural stability of a car body was evaluated.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.19-23
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• 1998

We enhanced the sensitivity of surface plasmon resonance biosensor by the conversion of the real-time direct binding immunoassay into the sandwich immunoassay, in which colloidal gold particles coated with anti-mouse IgG was used. By the immobilization of anti-mouse IgG onto the carboxymethyl dextran surface of thin gold film, the direct binding of analyte(mouse IgG) onto the sensor chip, and the injection of colloidal gold particles coated with anti-mouse IgG, about 100 times of sensitivity enhancement was obtained. This result suggests that nanoparticles, which has a high refractive index, homogeneous ultrafine structure and capability of size control, would be applicable for the detection of very small quantity of biomaterial.

• Journal of KSNVE
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• v.9 no.2
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• pp.248-257
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• 1999

This paper presents the model updating of an equipment panel by using modal test and sensitivity analysis. The equipment panel is one of the major structures of communication satelite, on which broadcasting and communication equipments are mounted. For high rigidity and light weight, the panel was designed as an aluminum honeycomb sandwich panel. In addition, heat pipes were embedded in the panel for thermal control. It is essential to improve the finite element model of a spacecraft structure by using modal test in order to verify that the satellite is designed and fabricated with adequate margin under launch environment. In this paper, Young's modulus of aluminumfacesheet was selected as a modified parameter in the sensitivity analysis. The effect of boundary conditions on model improvement was also investigated.

• Advances in aircraft and spacecraft science
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• v.3 no.3
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• pp.259-269
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• 2016

In this work results from an underwater experiment on flow-induced noise in the interior of a towed body generated from a surrounding turbulent boundary layer are presented. The measurements were performed with a towed body under open sea conditions at towing depths below 100 m and towing speeds ranging from 2.4 m/s to 6.2 m/s (4 kn to 12 kn). Focus is given in the experiments to the relation between (outer) wall pressure fluctuations and the (inner) hydroacoustic near-field on the reverse side of a flat plate. The plate configuration consists of a sandwich structure with an (thick) outer polyurethane layer supported by an inner thin layer from fibre-reinforced plastics. Parameters of the turbulent boundary layer are estimated in order to analyse scaling relations of wall-pressure fluctuations, interior hydroacoustic noise, and the reduction of pressure fluctuations through the plate.

• Journal of Aerospace System Engineering
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• v.15 no.4
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• pp.30-39
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• 2021

This paper presents a study on the design and structural substantiation of the interior structure of the new VVIP aircraft. In this study, the structural design and analysis of the compartment with aluminum alloy and sandwich composite panel were performed. The structural design requirements from the Federal Aviation Administration were identified. The structural analysis of the compartment was performed by the utilization of the finite element analysis method, for the structural design process. Therefore, the designed cabin compartment secured the structural integrity, and satisfied its certification standards and design requirements via structural analysis.

• Geomechanics and Engineering
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• v.36 no.4
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• pp.407-416
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• 2024

Dynamic response of a rock tunnels by laminated porous concrete beam reinforced by nanoparticles subjected to harmonic transverse dynamic load is investigated considering structural damping. The effective nanocomposite properties are evaluated on the basis of Mori-Tanaka model. The concrete beam is modeled by the exponential shear deformation theory (ESDT). Utilizing nonlinear strains-deflection, energy relations and Hamilton's principal, the governing final equations of the concrete laminated beam are calculated. Utilizing differential quadrature method (DQM) as well as Newmark method, the dynamic displacement of the concrete laminated beam is discussed. The influences of porosity parameter, nanoparticles volume percent, agglomeration of nanoparticles, boundary condition, geometrical parameters of the concrete beam and harmonic transverse dynamic load are studied on the dynamic displacement of the laminated structure. Results indicated that enhancing the nanoparticles volume percent leads to decrease in the dynamic displacement about 63%. In addition, with considering porosity of the concrete, the dynamic displacement enhances about 2.8 time.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.27-37
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• 2022

With the recent increase in the spread of ESS (Electric Storage System), the damage to human life and property is also rapidly increasing due to continuous fires caused by ESS. In the manufacture of urethane sandwich panels used in ESS, it is necessary to improve the flame retardant performance. In this study, in order to realize the flame retardant properties of flexible polyurethane foam, the effect of the tissue density of the product due to the change of the isocyanate functional group parameter that changes the physical properties of the product on the fire performance was studied. The product was manufactured by changing the density of the urethane structure, and combustion performance tests, gas toxicity tests, and smoke density tests were performed. As a result, it was confirmed that the total amount of heat released had excellent performance when the isocyanate functional group was high, and had no correlation with the maximum heat release rate. When the value of the isocyanate functional group was 2.7 or more, the collapse of the shape could be prevented. In the gas hazard test, the performance was increased when the isocyanate functional group was relatively high, so a flame retardant for the Char system, which had a dense structure and easy to form a carbonized film, was added. confirmed to be. Therefore, as a result of this study, it is thought that it will be possible to lay the foundation for the development of a flame retardant to replace the cheap urethane sandwich panel used in the past.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.55-60
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• 2010

The honeycomb composite joint structure designed for application to a tilting KTX railroad car body is subjected to bending loads of a cantilever type. Honeycomb sandwich composite panel-joint attached in the real tilting car body was fabricated and sectioned as several beam-joint specimens for the bending test. The fracture behaviors of these specimens under static loads were different from those under cyclic loads. Static bending loads caused shear deformation and fracture in the honeycomb core region, while fatigue cyclic bend loading caused delamination along the interface between the composite skin and the honeycomb core, and/or caused a fracture in the welded part jointed with the steel under-frame. These fracture behaviors could occur in other industrial honeycomb composite joints with similar sub-structures, and be used for improving design parameters of a honeycomb composite joint structure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.862-868
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• 2010

Development of a small scale aircraft has been carried out for the BASA(Bilateral Aviation Safety Agreement) program in Korea. This aircraft adopted all the composite structures for environmental friendly by low fuel consumption due to its lightness behavior. However the composite structure has s disadvantage which is very weak against impact due to foreign object damages. Therefore the aim of this study is focusing on the damage evaluation and repair techniques of the aircraft composite structure. The damages of composite laminates including the carbon/epoxy UD laminate and the carbon/epoxy fabric face sheets-honeycomb core sandwich laminate were simulated by a drop weight type impact test equipment and the damaged specimen were repaired using the external patch repair method after removing damaged area. The compressive strength test and analysis results after repairing the impact damaged specimens were compared with the compressive strength test and analysis results of undamaged specimens and impact damaged specimens. Finally, the strength recovery capability by repairing were investigated.

• Composites Research
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• v.17 no.3
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• pp.15-22
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• 2004

Acoustic load generated by rocket propulsion system is one of major dynamic loads during lift-off phase so that it causes the structural failure and electronic malfunction of payloads. Acoustic loads can be greatly reduced by an appropriate acoustical design of nose faring structures. This paper deals with the acoustical design of the nose fairing structure for launch vehicle. It is well known that a honeycomb sandwich structure is a poor sound insulator because of its high specific stiffness. In this paper, the sound transmission characteristics of four kinds of honeycomb structures for noise fairing were investigated by means of numerical and experimental ways. In order to estimate transmission loss, infinite plate theory by Moore and Lyon and statistical energy analysis (SEA) method were used. The predicted results showed a good agreement with measured ones. These enabled us to determine a proper core material for nose fairing, which shows good sound insulation performance per weight.