• Nuclear Engineering and Technology
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• v.43 no.5
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• pp.421-428
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• 2011

The out-of-pile mechanical performance and microstructure of recrystallized Zr-1.5 Nb-S alloy was investigated. The strength of the recrystallized Zr-1.5Nb-O-S alloys was observed to increase with the addition of sulfur over a wide temperature range, from room temperature up to $300^{\circ}C$. A yield drop and stress serrations due to dynamic strain were observed at room temperature and $300^{\circ}C$. Wavy and curved dislocations and loosely knit tangles were observed after strained to 0.07 at room temperature, suggesting that cross slip is easier. At $300^{\circ}C$, however, dislocations were observed to be straight and aligned along the slip plane, suggesting that cross slip is rather difficult. At $300^{\circ}C$, oxygen atoms are likely to exert a drag force on moving dislocations, intensifying the dynamic strain aging effect. Oxygen atoms segregated at partial dislocations of a screw dislocation with the edge component may hinder the cross slip, resulting in the rather straight dislocations distributed on the major slip planes. Recrystallized Zr-Nb-S alloys exhibited ductile fracture surfaces, supporting the beneficial effect of sulfur in zirconium alloys. Oxidation resistance in air was also found to be improved with the addition of sulfur in Zr-1.5 Nb-O alloys.

• Steel and Composite Structures
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• v.27 no.1
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• pp.1-12
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• 2018

This paper presents a semi-analytical solution of simply supported horizontally composite curved I-beam by trigonometric series. The flexibility of the interlayer connectors between layers both in the tangential direction and in the radial direction is taken into account in the proposed formulation. The governing differential equations and the boundary conditions are established by applying the variational approach, which are solved by applying the Fourier series expansion method. The accuracy and efficiency of the proposed formulation are validated by comparing its results with both experimental results reported in the literature and FEM results.

• Journal of the Korean institute of surface engineering
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• v.8 no.2
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• pp.20-27
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• 1975

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.178-185
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• 1999

For the process control of silicon nitride gelcasting, the composition effect of acryamide system on the viscosity of slip and mechanical property of gelcast green body were investigated. The slip was prepared by ball milling of silicon nitride suspension prepared with acrylamide monomer and polyelectrolyte dispersant after premixing them by attritor. The slip mixed with initiator was vacuum deaired and cast into molds, and then polymerized. The consolidated green body was obtained by drying the gelated slip. The viscosity measument and the diametral compression test was done to evaluate the rheological behaviro of slip and mechanical property of gelcast body, respectively. Experimental results showed that the high solid loading of silicon nitride slip was obtained up to 46 vol% with a low viscosity. The mechanical property of gelcast body mainly increased with increasing the concentration of monomer. The gelcast body was machinable above the ∼3 MPa of tensile strength. The relative density of pressured-sintered body was 98.5% at 1760$^{\circ}C$, 3 h.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1543-1549
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• 2012

This study focuses on the state space model and the design of a state observer for the slip dynamics between rolls in STS cold cluster mills. First, a mathematical model of the roll slip is given as a nonlinear differential equation. Then, by using a Taylor series expansion, it is linearized as a state space model. Next, by using Gopinath's algorithm, a minimal-order state observer based on the state space model is designed to estimate the angular speed of all idle rolls except for an actuated roll that is measureable. Finally, a computer simulation is used to validate that the proposed state space model very well describes slip dynamics between, and moreover, the state observer very well estimates the angular speed of the idle roll.

• Steel and Composite Structures
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• v.38 no.5
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• pp.563-582
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• 2021

The present study experimentally and analytically investigated the push-out behaviour of H-shaped steel section embedded in ultrahigh-performance fibre-reinforced concrete (UHPFRC). The effect of significant parameters such as the concrete types, fibre content, embedded steel length, transverse reinforcement ratio and concrete cover on the bond stress, development of bond stress along the embedded length and failure mechanism has been reported. The test results show that the bond slip behaviour of steel-UHPFRC is different from the bond slip behaviour of steel-normal concrete and steel-high strength concrete. The bond-slip curves of steel-normal concrete and steel-high strength concrete exhibit brittle behaviour, and the bond strength decreases rapidly after reaching the peak load, with a residual bond strength of approximately one-half of the peak bond strength. The bond-slip curves of steel-UHPFRC show an obvious ductility, which exhibits a unique displacement pseudoplastic effect. The residual bond strength can still reach from 80% to 90% of the peak bond strength. Compared to steel-normal concrete, the transverse confinement of stirrups has a limited effect on the bond strength in the steel-UHPFRC substrate, but a higher stirrup ratio can improve cracking resistance. The experimental campaign quantifies the local bond stress development and finds that the strain distribution in steel follows an exponential rule along the steel embedded length. Based on the theory of mean bond and local bond stress, the present study proposes empirical approaches to predict the ultimate and residual bond resistance with satisfactory precision. The research findings serve to explain the interface bond mechanism between UHPFRC and steel, which is significant for the design of steel-UHPFRC composite structures and verify the feasibility of eliminating longitudinal rebars and stirrups by using UHPFRC in composite columns.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.11a
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• pp.75-79
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• 1991

자동차 엔진, 점프, 모우터 둥과 같은 회전동력장치의 일률이나 효율을 측정하거나 혹은, 회전동력장치를 과부하 없이 운용하고자 할 때 토오크센서를 이용한다. 이 때 사용되는 토오크센서는 대부분 strain gage와 slip ring을 이용하고 있는 데, 이러한 종류의 센서들은 감지된 토오크를 회전하는 축으로부터 외부로 그 신호를 전달하기 위해서 slip ring 이나 magnetic coupler와 같은 중간의 신호 전달장치 ( signal transmitter )를 설치하여야 한다.(중략)

• Journal of applied mathematics & informatics
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• v.37 no.5_6
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• pp.429-442
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• 2019

This article addresses the influence of partial slip condition in the hydromagnetic flow of Burgers fluid in a rotating frame of reference.The flows are induced by oscillation of a boundary. Two problems for oscillatory flows are considered. Exact solutions to the resulting boundary value problems are constructed. Analysis has been carried out in the presence of magnetic field. Physical interpretation is made through the plots for various embedded parameters.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.2
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• pp.110-121
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• 1981

In order to study on the fracture behavior and the fracture thoughness of combined structure, the specimens, structural steel (SM28C) and 6:4 brass are annealed for ductility and investigated for the befavior of fracture and the absorbed energy at the variation of the impact velocity. The results obtained by this study are as follows: (1)The maximum load increases with the impact velocity, but in the condition of constant impact velocity it decreases as the ductility increases. (2)The absorbed energy increases with the impact velocity, but in the condition of constant impact velocity it is constant as the ductility increases. (3)In the case of the combined structure of peralite and ferrite, the microcracks initiates and propagates mainly in the ferrite structure intergranular in accompany with the slip, and the slip concentration phenomena occur in the boundary of pearlite structure However, in case of the combined structure of .alpha. and ..betha. phase, the microcracks initiates and propagares mainly in the .alpha. phase intergranularly, and slip concentration phenomena not ocur in the boundary of .betha. phase.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.389-395
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• 2001

To restrain contact failure, present study investigates the influence of edge machining of an indenter (punch). As for the edge machining, rounding, chamfering, and chamfering and rounding are considered. Contact mechanics is consulted to examine the traction profile and the size of the contact region which are directly influenced by the end profile of the indenter. The effect of rounding size (i.e., radius) in the case of the chamfering and rounding edge-indenter is studied. Shear traction is also evaluated within the regime of partial slip. Size of slip region and its expansion rate due to the increase of shear force are considered to investigate the shape effect of the indenter on contact failure.