• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.834-837
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• 2005

This study presents a study on the influence of process parameters(semi-die angle, die reduction, friction condition, and bearing length) in drawn wire on residual stresses were investigated using FE-analysis. In this study, semi-die angle and die reduction have a significant effect on the residual stresses at the surface of drawn wire. In the previous study, in order to reduce the residual stresses, several methods were suggested: addition of axial tension, application of skin pass, straightening in multi-roll straightener etc. In this study, it can be known that the concurrent application of skin pass with low die reduction and low semi-die angle at the final stage of drawing operation reduces dramatically the both axial and hoop residual stresses after drawing.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.5
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• pp.254-261
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• 2020

The structural safety of hydraulic winch drum and the gears are estimated by the Finite Element Analysis (FEA) and the winch operation experiment. The mesh convergence test is performed and the applied force is the pressure on the drum converted from the rope tension in working condition. The stress of the drum calculated from the strain values of the winch operation experiment shows the agreement with that from the FEA. Most stress values are under the yield strength except for the small hole made for the wire rope fixation. The life of bearings in the drum is calculated using the life prediction formula with the reaction forces from the operation load. One of the two ball bearings shows the short life for impact condition, yet the real prototype winch system shows more life than the numerical value.

• Computers and Concrete
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• v.12 no.2
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• pp.131-149
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• 2013

Various types of reinforcement splicing methods have been developed and implemented in reinforced concrete construction projects for achieving the continuity of reinforcements. Due to the complicated reinforcement arrangements and the difficulties in securing bar spacing, the traditional lap splicing method, which has been widely used in reinforced concrete constructions, often shows low constructability and difficulties in quality control. Also, lap spliced regions are likely to be over-reinforced, which may not be desirable in seismic design. On the other hand, mechanical splicing methods can offer simple and clear arrangements of reinforcement. In order to utilize the couplers for the ribbed-deformed bars, however, additional screw processing at the ends of reinforcing bars is typically required, which often lead to performance degradations of reinforced concrete members due to the lack of workmanship in screw processing or in adjusting the length of reinforcing bars. On the contrary, the use of screw-ribbed reinforcements can easily solve these issues on the mechanical splicing methods, because it does not require the screw process on the bar. In this study, the mechanical coupler suitable for the screw-ribbed reinforcements has been developed, in which any gap between the reinforcements and sleeve device can be removed by grouting high-flow inorganic mortar. This study presents the uniaxial tension tests on the screw-ribbed reinforcement with the mechanical sleeve devices and the cyclic loading tests on RC columns with the developed coupler. The test results show that the mechanical sleeve connection developed in this study has an excellent splicing performance, and that it is applicable to reinforced concrete columns with a proper confinement by hoop reinforcement.

• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.13-17
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• 2015

In superconducting coil applications particularly in wet wound coils, coated conductor (CC) tapes are subjected to different type of stresses. These include hoop stress acting along the length of the CC tape and the Lorentz force acting perpendicular to the CC tape's surface. Since the latter is commonly associated with delamination problem of multi-layered CC tapes, more understanding and attention on the delamination phenomena induced in the case of coil applications are needed. Difference on the coefficient of thermal expansion (CTE) of each constituent layer of the CC tape, the bobbin, and the impregnating materials is the main causes of delamination in CC tapes when subjected to thermal cycling. The CC tape might also experience cyclic loading due to the energizing scheme (on - off) during operation. In the design of degradation-free superconducting coils, therefore, characterization of the delamination behaviors including mechanism and strength in REBCO CC tapes becomes critical. In this study, transverse tensile tests were conducted under different loading conditions using different size of upper anvils on the GdBCO CC tapes. The mechanical and electromechanical delamination strength behaviors of the CC tapes under transverse tensile loading were examined and a two-parameter Weibull distribution analysis was conducted in statistical aspects. As a result, the CC tape showed similar range of mechanical delamination strength regardless of cross-head speed adopted. On the other hand, cyclic loading might have affected the CC tape in both upper anvil sizes adopted.

• Journal of the Korean Institute of Gas
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• v.5 no.3 s.15
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• pp.73-79
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• 2001

The corner protection which is consist of insulation and $9\%$ nickel liner is designed to mitigate the high hoop tension at the corner of LNG storage tank by LNG leakage. So the design loads depend on thermal and liquid pressure from leaked LNG In this paper design conditions are suggested as operating, major and minor leak conditions. And in order to check integrity of comer protection for the design conditions by appendix 4 in ASME section VIII div.2, acceptability checking process that have stress categorization and finite element analysis is explained.

• Journal of Convergence for Information Technology
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• v.7 no.5
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• pp.103-109
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• 2017

A pressure vessel is a cylindrical container that accommodates a pressurized fluid. In real life, there are propane canisters and butane canisters. According to data from the Korea Gas Safety Corporation, The number of domestic gas accidents is average 33 cases of domestic gas accidents occurred per year and 20.8 for mobile butane gases. The purpose of this study was to investigate a method to prevent this kind of explosion. Common studies include forced drain through safe holes, forced separation of butane canisters, and manufacturing of high-strength steel. This paper uses a concept that reduces stress inside the cylinder using prestressed method that precede compression. In other words, install a long liner in both ends of the pressure vessel. I want to develop a safety device that acts like a gas intermediate valve.

• Composites Research
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• v.21 no.3
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• pp.9-17
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• 2008

In this paper, the low velocity impact characteristics of filament winding CFRP pressure vessel was investigated using numerical and experimental methods. The cylinder part of CFRP vessel was impacted using triangular shape impactor which simulated the sharp edge of dropping tools and impact response behavior of CFRP was reviewed. The mechanical behavior, such as deformation and stress distribution, were also predicted by explicit finite element method and the validity of the model was investigated. For the quantitative evaluation of the residual strength of the pressure vessel after impact, a series of the ring specimens was cut from the impacted vessel and its burst pressure was measured by hydraulic pressure hoop tension test. As the results, the relationship between the residual strength degradation and the impact energy was successively obtained and a useful methodology to evaluate quantitatively the impact damage tolerance of CFRP pressure vessel was established.