• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.75-83
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• 2013

This paper presents a series of test result in order to study fire resistance capacity of the Near-Surface-Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) plate, which are tensile test of CFRP under various temperature loading, temperature loading test of epoxy and bond test of NSM CFRP to concrete under various temperature loading. From the tests, it was found that NSM retrofit method had high efficiency in strengthening concrete under ordinary temperature. However, the strength of the system was able to be drastically decreased even a little increase of surrounding temperature. Especially, bond capacity begins to disappear when the surrounding temperature approaches the glass transition temperature of epoxy. Therefore, it is necessary to improve the fire resistance capacity of both fiber reinforced polymer reinforcement and epoxy for bonding in order to develop safe fire resistance design of structure.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.223-229
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• 2023

Seawater batteries are next-generation secondary batteries that use seawater as a cathode. They utilize marine resources to provide competitive prices, high eco-friendliness, and a structure suitable for marine applications. Based on these advantages, pouch types and prismatic types have been studied and developed assuming natural seawater exposure. However, because of the electrical characteristics of the secondary battery, its capacity and internal resistance vary depending on the use environment. These characteristics are not only utilized for predicting the life of a battery but also have a direct effect on the capacity and power suitable for a specific situation. Therefore, the internal resistance was analyzed in this study by measuring the capacity depending on the seawater battery use environment and the state-of-charge-open-circuit-voltage measurement method.

• Structural Engineering and Mechanics
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• v.47 no.2
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• pp.247-263
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• 2013

It is evident that torsional resistance of a reinforced concrete (RC) member is attributed to both concrete and steel reinforcement. However, recent structural design codes neglect the contribution of concrete because of cracking. This paper reports on the results of an experimental and numerical investigation into the torsional capacity of concrete beams reinforced only by longitudinal rebars without transverse reinforcement. The experimental investigation involves six specimens tested under pure torsion. Each specimen was made using a cast-in-place concrete with different amounts of longitudinal reinforcements. To create the torsional moment, an eccentric load was applied at the end of the beam whereas the other end was fixed against twist, vertical, and transverse displacement. The experimental results were also compared with the results obtained from the nonlinear finite element analysis performed in ANSYS. The outcomes showed a good agreement between experimental and numerical investigation, indicating the capability of numerical analysis in predicting the torsional capacity of RC beams. Both experimental and numerical results showed a considerable torsional post-cracking resistance in high twist angle in test specimen. This post-cracking resistance is neglected in torsional design of RC members. This strength could be considered in the design of RC members subjected to torsion forces, leading to a more economical and precise design.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.2
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• pp.184-190
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• 2011

The membrane properties (membrane resistance and ion exchange capacity) of the five types of commercial anion exchange membrane, i.e. IOMAC, AHT, APS, AHA, AFN, were evaluated for the application in the alkaline electrolysis. The membrane resistance decreased in the order; in 1M KOH: AHT>IOMAC>AHA>AFN>APS; in 1M NaOH: AHT>IOMAC>AHA>APS>AFN. The ion exchange capacity decreased in the order: AFN>APS>AHT>AHA>IOMAC. The membrane life was determined from the change of membrane resistance in 1M KOH and NaOH with an increase of soaking time in 20 wt% KOH and 30 wt% NaOH solution. AHA membrane had a good membrane life in 20 wt% NaOH with its unchanged membrane resistance. And, AFN and AHA membrane had a good membrane life in 30 wt% NaOH with its unchanged membrane resistance.

• Steel and Composite Structures
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• v.35 no.4
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• pp.509-525
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• 2020

Steel-concrete composite slabs with profiled steel sheeting are widely used in the execution of floors in steel and composite buildings. The rapid construction process, the elimination of conventional replaceable shuttering and the reduction of temporary support are, in general, considered the main advantages of this structural system. In slabs with the spans currently used, the longitudinal shear resistance commonly provided by the embossments along the steel sheet tends to be the governing design mode. This paper presents an innovative reinforcing system that increases the longitudinal shear capacity of composite slabs. The system is constituted by a set of transversal reinforcing bars crossing longitudinal stiffeners executed along the upper flanges of the steel sheet profiles. This type of reinforcement takes advantage of the high bending resistance of the composite slabs and increases the slab's ductility. Two experimental programmes were carried out: a small-scale test programme - to study the resistance provided by the reinforcing system in detail - and a full-scale test programme to test simply supported and continuous composite slabs - to assess the efficacy of the proposed reinforcing system on the global behaviour of the slabs. Based on the results of the small-scale tests, an equation to predict the resistance provided by the proposed reinforcing system was established. The present study concludes that the resistance and the ductility of composite slabs using the reinforcing system proposed here are significantly increased.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.241-246
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• 2007

The capacity of a lateral load resistance of a joint with Jangbu-connection of Dori-directional frame in traditional wood structure system was studied, through experiments of 1/2 scaled and T-shaped 7 subassemblies of joint of Dori-directional frame for Deawoongjeon of Bongjungsa. From the experiment, it was shown that the capacity of a lateral load resistance was influenced by the vertical load confining joint and not influenced by the number of Chok and the depth of Changbang, And lateral load resistance mechanism is developed by the restraint between the vertical load and the contacting edge of column; if structure is pushed to the left, the top-right end of Pyeongju contacts with Changbang and left Changbang loses the contacts with Pyeongju and therefore only right Changbang can resist to lateral load.

• Steel and Composite Structures
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• v.1 no.2
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• pp.187-200
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• 2001

Most of the portal frames are designed these days by the application of plastic analysis, with the normal assumption being made that the column bases are pinned. However, the couple produced by the compression action of the inner column flange and the tension in the holding down bolts will inevitably generate some moment resistance and rotational stiffness. Full-scale portal frame tests conducted during a previous research program had suggested that this moment can be as much as 20% of the moment of resistance of the column. The size of this moment of resistance is particularly important for the design of the tensile capacity of the holding down bolts and also the bearing resistance of the foundation. The present research program is aiming at defining this moment of resistance in simple design terms so that it could be included in the design of the frame. The investigation also included the study of the semi-rigid behaviour of the column base/foundation, which, to a certain extent, affects the overall loading capacity and stiffness of the portal frames. A series of column bases with various details were tested and were used to calibrate a finite element model which is able to simulate the action of the holding down bolts, the effect of the concrete foundation and the deformation of the base plate.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.3
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• pp.23-30
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• 2019

In this study, we evaluated the applicability of proper embedded depth of fillings by examining the uplift resistance using spiral foundation and top base foundation. As a result of the model test, the maximum uplift resistance increased with the embedded depth. The maximum uplift resistance of each region was found to be 50cm depth. The spiral foundation was 335.14N of Sancheong, 312.32N of Seongju, 403.94N of Wanju, and the top base foundation was 745.06N of Sancheong, 1028.82N of Seongju and 950.76N of Wanju. The yield point after the elastic section in the stress-displacement graph of the top base foundation was calculated as the maximum uplift resistance. For this reason, farmers do not actually use top bases foundation. Therefore, it was considered that the additional load increase due to slip connector will not occur. Model test results show that the maximum uplift resistance increases with the purlinss installed under the ground. Therefore, additional comparative studies through purlins installation will be needed.

• Steel and Composite Structures
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• v.9 no.5
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• pp.397-418
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• 2009

Eight panel specimens were tested in one-way bending to study the behaviour and capacity of composite slab joists consisting of cold-formed steel C-sections and concrete. Various shear transfer mechanisms were implemented on the C-section flange embedded in the concrete to provide the longitudinal shear resistance. Results showed that all specimens reached serviceability limit state while in elastic range and failure was ductile. Shear transfer achieved for all specimens ranged from 42 to 99% of a full transfer while specimens employed with shear transfer enhancements showed a greater percentage and therefore a higher strength compared with those relying only on surface bond to resist shear. The implementation of pre-drilled holes on the embedded flange of the steel C-section was shown to be most effective. The correlation study between the push-out and panel specimens indicated that the calculated moment capacity based on shear transfer resistance obtained from push-out tests was, on average, 10% lower than the experimental ultimate capacity of the panel specimen.

• Steel and Composite Structures
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• v.15 no.6
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• pp.705-724
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• 2013

The behaviour of steel column at elevated temperature is significantly different than that at ambient temperature due to its changes in the mechanical properties with temperature. Reported literature suggests that steel column may become vulnerable when exposed to fire condition, since its strength and capacity decrease rapidly with temperature. The present study aims at investigating the lateral load resistance of non-insulated steel columns under fire exposure through finite element analysis. The studied parameters include moment-rotation behaviour, lateral load-deflection behaviour, stiffness and ductility of columns at different axial load levels. It was observed that when the temperature of the column was increased, there was a significant reduction in the lateral load and moment capacity of the non-insulated steel columns. Moreover, it was noted that the stiffness and ductility of steel columns decreased sharply with the increase in temperature, especially for temperatures above $400^{\circ}C$. In addition, the lateral load capacity and the moment capacity of columns were plotted against fire exposure time, which revealed that in fire conditions, the non-insulated steel columns experience substantial reduction in lateral load resistance within 15 minutes of fire exposure.