• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.7-14
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• 2008

• Magazine of the Korea Institute for Structural Maintenance and Inspection
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• v.17 no.4
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• pp.61-67
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• 2013

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.71-77
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• 2018

This paper suggests how to improve the fatigue strength of an axle shaft, which is the vulnerable part of an axle shaft system for a 3.5-ton commercial vehicle. The axle shaft is composed of a universal joint with a spider and yoke, yoke shaft, and so on. Structural analysis of the initial axle shaft was conducted to select the exact area for structural strength fatigue improvement, and as a result, the inner/outer yoke shaft and spider were selected. Four cases considered design variables, such as length and thickness, to verify the enhanced durability of the axle shaft, and fatigue analysis was conducted. Finally, we suggest that the axle shaft system satisfied the working conditions for a 3.5-ton commercial vehicle.

• International Journal of Concrete Structures and Materials
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• v.10 no.1
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• pp.75-85
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• 2016

Fire ranks high among the potential risks faced by most buildings and structures. A full understanding of temperature effects on fiber reinforced concrete is still lacking. This investigation focuses on the study of the residual compressive strength, stress strain behavior and surface cracking of structural polypropylene fiber-reinforced concrete subjected to temperatures up to $300^{\circ}C$. A total of 48 cubes was cast with different fiber dosages and tested under compression after exposing to different temperatures. Concrete cubes with varying macro (structural) fiber dosages were exposed to different temperatures and tested to observe the stress-strain behavior. Digital image correlation, an advanced non-contacting method was used for measuring the strain. Trends in the relative residual strengths with respect to different fiber dosages indicate an improvement up to 15 % in the ultimate compressive strengths at all exposure temperatures. The stress-strain curves show an improvement in post peak behavior with increasing fiber dosage at all exposure temperatures considered in this study.

• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.483-496
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• 2017

Earthquake excitations may induce important amount of seismic energy into structures. Current design philosophy mainly deals with the plastic deformations of replaceable energy dissipating devices rather than damages accumulated on structural members. Since earthquake damage is substantially concentrated on these devices they could be replaced after severe earthquakes. In this study, the efficiency of steel cushion (SC) on seismic improvement of a vulnerable reinforced concrete (RC) frame is determined by means of several numerical simulations. The cyclic shear behaviors of SCs were determined by performing quasi-static tests. The test results were the main basis of the theoretical model of SCs which were used in the numerical analysis. These analyses were performed on three types of RC frames namely bare frame (BF), full-braced frame (F-BF) and semi-braced frame (S-BF). According to analysis results; implementation of SCs has considerable effects in reducing the storey shear forces and storey drifts. Moreover plastic energy demands of structural elements were reduced which indicates a significant improvement in seismic behavior of the RC frame preventing damage accumulation on structural elements. Full-braced frame having SCs with the thickness of 25 mm has better performance than semi-braced frame interms of energy dissipation. However, global energy dissipation demand of S-BF and F-BF having SCs with the thickness of 18 mm are almost similar.

• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.177-186
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• 1998

The concrete filled steel tubular column have to superior in compressive load carrying capacity, compared with same section typed hollow steel tube column, and have many excellent structural properties, such as stiffness improvement by filled concrete, improvement of ductility by reinforced effect of local buckling, and the like. However, it has not clear the effect of interaction between steel tube and filled concrete, stress portion ratio and fracture mechanism of concrete. This study investigated to structural properties for high strength concrete filled steel tube column by loading conditions through a series of experiments. Especially, this study investigated the properties of structural behaviors for concrete filled steel tube column stress ratio by loading conditions and failure mechanism of filled concrete.

• Journal of the Korean Society of Industry Convergence
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• v.13 no.4
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• pp.197-203
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• 2010

Laser welding is widely used for precision welding because of superior mechanical properties and high productivity. Generally the accuracy of the welding is determined by the distribution of the bead which is affected by the structural vibrations of the equipment. This study was originated to stabilize a laser welding machine to minimize the bead distribution for the precise joining. The structural properties of the laser welding machine have been investigated to analyze the major factors of the vibrations to cause the bead distribution. The ideas for the design improvement have been applied to the simulation model to identify the effects and further to achieve the stability design and to minimize the bead distribution. The result shows that a few simple design alterations can substantially suppress the structural vibrations and improve the welding accuracy. The procedure used for this study can also be applied to similar welding equipments for improving the structural stability and the welding accuracy.

• Structural Engineering and Mechanics
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• v.66 no.2
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• pp.229-235
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• 2018

This study investigated the behaviour of the simply supported hollow steel tube (HST) beams, either concrete filled or unfilled when strengthened with carbon fibre reinforced polymer (CFRP) sheets. Eight specimens with varied tubes thickness (sections classification 1 and 3) were all tested experimentally under static flexural loading, four out of eight were filled with normal concrete (CFST beams). Particularly, the partial CFRP strengthening scheme was used, which wrapped the bottom-half of the beams cross-section (U-shaped wrapping), in order to use the efficiency of high tensile strength of CFRP sheets at the tension stress only of simply supported beams. In general, the results showed that the CFRP sheets significantly improved the ultimate strength and energy absorption capacities of the CFST beams with very limited improvement on the related HST beams. For example, the load and energy absorption capacities for the CFST beams (tube section class 1) were increased about 20% and 32.6%, respectively, when partially strengthened with two CFRP layers, and these improvements had increased more (62% and 38%) for the same CFST beams using tube class 3. However, these capacities recorded no much improvement on the related unfilled HST beams when the same CFRP strengthening scheme was adopted.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.85-86
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• 2019

Recently, the educational facilities were 45% among total damaged facilities from the Po-Hang earthquake. Consequently, the seismic reinforcement of existing educational facilities were ended up attracting people's interesting. However, research is insufficient to consider that how far technology has been developed. Therefore, the purpose of this study is to investigate the level of domestic guideline research by comparing to foreign guidelines in regard to seismic reinforcement methods applicable to existing educational facilities. To achieve the objective, first, the current status of seismic reinforcement projects in domestic educational facilities was analyzed. Second, the domestic and foreign seismic reinforcement methods guidelines for structural, non-structural was compared. Third, the improvement directions for future guidelines were suggested. As a results, the improvement directions of domestic seismic reinforcement methods guidelines were proposed. First, the structural seismic reinforcement strategy needs to be segmented. Second, it is necessary to analyze about non-structural guidelines based on additional cases. In the future, this study can be used as a basic material for developing seismic reinforcement methods guidelines in domestic existing educational facilities.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.346-351
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• 2007

As the construction technology is rapidly advancing internationally, the necessity of virtual construction technology development is drastically demanded in the construction industry together with a fusion technology with information technology(IT). The construction technology will be changed as the paradigm of construction technology in the future. The establishment of building structural system in the virtual construction basis is necessary for the integration of construction process, and it will be expected to produce the effect of reduction of construction period and quality improvement through the environment of integration. This study is to present the analysis of the existing process of structural design, the content of research & development as per the building structural system on virtual construction basis and the direction of research.