• Smart Structures and Systems
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• v.30 no.3
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• pp.327-332
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• 2022

In building envelope, transparent components play an important role. The structural glazing systems are the weak element of the casing in terms of mechanical resistance, thermal and acoustic insulation. In the present work, new structural glass panels with granular aerogel in interspace were investigated from different points of view. In particular, the mechanical characterization was carried out in order to assess the resistance to bending of the single glazing pane. To this end, a special instrument system was built to define an alternative configuration of the coaxial double ring test, able to predict the fracture strength of glass large samples (400 × 400 mm) without overpressure. The thermal and lighting performance of an innovative double-glazing façade with granular aerogel was evaluated. An experimental campaign at pilot scale was developed: it is composed of two boxes of about 1.60 × 2 m² and 2 m high together with an external weather station. The rooms, identical in terms of size, construction materials, and orientation, are equipped with a two-wing window in the south wall surface: the first one has a standard glazing solution (double glazing with air in interspace), the second room is equipped with the innovative double-glazing system with aerogel. The indoor mean air temperature and the surface temperature of the glass panes were monitored together with the illuminance data for the lighting characterization. Finally, a brief energy characterization of the performance of the material was carried out by means of dynamic simulation models when the proposed solution is applied to real case studies.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.24-29
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• 2021

Recently, owing to the high demand for eco-friendly cars in the automotive industry, noise and vibrations have become major challenges. The use of laminated damping steel is increasing in response to these demands. Laminated damping steel is primarily used in sound insulation plates. The vibration energy is converted into thermal energy due to the viscoelastic resin being located between two steel sheets and being able to damp the vibrations when an external force, such as, noise or vibration is applied to the steel plate. Laminated damping steel is chiefly applied to dash panels in automotive body parts, and because of its structure, junction technology for bonding with other components is necessary. However, there has not been sufficient research conducted on junctions. In this study, regardless of the electrode shape, in the range of 4.0 ~ 8.0 kA welding current, the same welding force and welding time were applied which were 2.8 kN and 200 m/s (12 cycles) and the tensile shear load and nugget size were analyzed after the resistance spot welding between different materials of laminated damping steel with a thickness of 1.035 mm. The results show that in the range of 5 ~ 8 kA welding current, 1.035 mm laminated damping steel meets the MS181-15 standard, which is the technical standard of Hyundai-Kia Motors.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.17 no.2
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• pp.119-125
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• 2021

Subsea pipelines are widely used to transport hydrocarbons from ultra-deep seawater to facilities on the coast. A sandwich pipe is a pipe-in-pipe system in which the annulus between the two concentric steel pipes is filled with polymer cores and fillers for insulation and structural reinforcement. Sandwich pipeline is always exposed to complex loading such as bending moment, bulking, internal and external pressures caused by installation, operation and environmental factors. This research provides insights into the structural integrity of sandwich pipeline exposed to complex loading conditions using a linear matching method (LMM). The finite element model of the sandwich pipeline has been generated from previous research, and the model validation is performed by comparing the results of the linear analysis between the two models. The temperature dependent material properties are used to simulate the behavior of real pipeline, and the elastic-perfectly plastic (EPP) model has been taken into account for the material non-linearity. Numerical results provide comprehensive insights into the structural response of the sandwich pipeline under monotonic and cyclic loading and provide notable points about the evaluation of the plastic collapse limit and the elastic shakedown limit of the sandwich pipeline.

• Progress in Superconductivity
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• v.9 no.1
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• pp.23-28
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• 2007

In order to have a superconductive connection between the wire-wound pickup coil and input coil, typically Nb terminal blocks with screw holes are used. Since this connection structure occupies large volume, large stray pickup area can be generated which can pickup external noise fields. Thus, SQUID and connection block are shielded inside a superconducting tube, and this SQUID module is located at some distance from the distal coil of the gradiometer to minimize the distortion or imbalance of uniform background field due to the superconducting module. To operate this conventional SQUID module, we need a higher liquid He level, resulting in shorter refill interval. To make the fabrication of gradiometers simpler and refill interval longer, we developed a novel method of connecting the pickup coil into the input coil. Gradiometer coil wound of 0.125-mm diameter NbTi wires were glued close to the input coil pads of SQUID. The superconductive connection was made using an ultrasonic bonding of annealed 0.025-mm diameter Nb wires, bonded directly on the surface of NbTi wires where insulation layer was stripped out. The reliability of the superconductive bonding was good enough to sustain several thermal cycling. The stray pickup area due to this connection structure is about $0.1\;mm^2$, much smaller than the typical stray pickup area using the conventional screw block method. By using this compact connection structure, the position of the SQUID sensor is only about 20-30 mm from the distal coil of the gradiometer. Based on this compact module, we fabricated a magnetocardiography system having 61 first-order axial gradiometers, and measured MCG signals. The gradiometers have a coil diameter of 20 mm, and the baseline is 70 mm. The 61 axial gradiometer bobbins were distributed in a hexagonal lattice structure with a sensor interval of 26 mm, measuring $dB_z/dz$ component of magnetocardiography signals.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.780-787
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• 2019

As a carbon-free, green growth alternative, internal and external interest in hydrogen energy and technology is growing. Hydrogen was added to co-axial methane, methane-propane, and methane-propane-ethane diffusion flames, which are the main ingredients of LNG, to evaluate its effect on flame formation and combustion products. The variation in combustion products produced by adding hydrogen gradually to diffusion pyrolysis at room temperature and normal pressure conditions was observed experimentally by using a gas analyzer, and the shape of diffusion pyrolysis was observed step by step using a digital camera. The experimental results showed that the production volume of nitrogen oxides tended to increase and became close to linear as hydrogen was added to the diffusion pyrotechnic. This is because the relatively high temperature of heat insulation and fast combustion speed of hydrogen facilitated the production of thermal NOx. On the other hand, CO2 production tended to decrease as hydrogen was added to reduce the overall carbon ratio contained in the mixed diffusion flame of methane, methane-propane, and methane-ethane-propane. This means that the mixed fuel use of LNG-hydrogen in ships may potentially reduce emissions of CO2, a greenhouse gas.

• Fire Science and Engineering
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• v.25 no.6
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• pp.83-88
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• 2011

This study presented the structure and characteristics of vinyl cords used for wiring electric equipment and appliances and analyzed the photographs of damaged flat-type vinyl cords (VFF, $1.25mm^2$) and the metallic cross-sectional structure of melted conductors. Normal VFFs were made by twisting several strands together and the surface of the conductor was red brown. In addition, from the analysis of the metallic structure of the conductor, it was found that its grains had been elongated. The surface of a VFF damaged by normal flame showed no sheen with carbonized insulation material fused on the conductor surface. In addition, from the analysis of the cross-sectional structure of the melted area, it was found that voids of a certain shape were formed on it but that the cord's own elongation structure could not be checked. The cross-sectional analysis of the melted conductor damaged by the external flame applied to a VFF to which electric current was being applied showed no elongation structure for each cord, and revealed that irregular voids and a columnar structure had grown. The surface of the VFF damaged by overcurrent was uniformly carbonized and the cross-sectional structure analysis of the melted conductor revealed that the dendritic structure had grown. The analysis of the characteristics of the VFF melted by short-circuit showed that even though some part of the surface was contaminated, it showed little sheen and that the area rebounded by melting was round in shape. In addition, the cross-sectional structure analysis using a metallurgical microscope showed the boundary surface and columnar structure and revealed an amorphous structure like normal copper at areas other than the melted conductor.