• Transactions of Materials Processing
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• v.28 no.5
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• pp.287-293
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• 2019

The plastic strain ratio is one of the factors of the deep drawability of metal sheets. The plastic strain ratio of Al sheet is low value. Therefore, it is necessary to increase the plastic strain ratio in order to improve the deep drawability of the Al sheet. This study investigated the increase in the plastic strain ratio and the texture change of AA1050 Al sheet after the hot asymmetric rolling. The average plastic strain ratio of initial AA1050 Al sheets was 0.41. After 84% hot asymmetric rolling at $400^{\circ}C$, the average plastic strain ratio was 0.77. The average plastic strain ratio of 84% hot asymmetrically rolled AA1050 Al sheet at $400^{\circ}C$ is 1.9 times higher than that of initial AA1050 Al sheet. The ${\mid}{\Delta}R{\mid}$ of 84% hot asymmetrically rolled AA1050 Al sheet at $400^{\circ}C$ is 1/2 times lower than that of initial AA1050 Al sheet. This result is due to the development of the intensity of the ${\gamma}-fiber$ texture and the decrease of the intensity of {001}<100> texture after the hot asymmetric rolling of AA1050 Al sheet.

• Transactions of Materials Processing
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• v.28 no.5
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• pp.281-286
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• 2019

The plastic strain ratio is one of the factors of the deep drawability of metal sheets. The plastic strain ratio of Al sheet is low value. Therefore, it is necessary to increase the plastic strain ratio in order to improve the deep draw ability of the Al sheet. This study investigated the increase of the plastic strain ratio and the texture change of AA3003 sheet after the hot asymmetric rolling. The average plastic strain ratio of the initial AA3003 sheets was 0.69. After 83% hot asymmetric rolling at $200^{\circ}C$, the average plastic strain ratio was 0.83. The average plastic strain ratio of the 83% hot asymmetrically rolled AA3003 sheet at $200^{\circ}C$ is 1.2 times higher than that of the initial AA3003 sheet. The ${\mid}{\Delta}R{\mid}$ of 83% hot asymmetrically rolled AA3003 sheet at $200^{\circ}C$ is 0.83 times lower than that of the initial AA3003 sheet. This result is due to the development of the intensity of ${\gamma}-fiber$ texture and reduces the intensity of {001}<110> and {001}<100> textures after hot asymmetric rolling of AA3003 sheet.

• Elastomers and Composites
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• v.44 no.4
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• pp.391-396
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• 2009

This paper presents the numerical analysis of thread rolling. Firstly, the analysis is focused on the effective analysis conditions that guarantee the reliability of the analysis results. The investigated parameters are the number of teeth and the number of elements. Using the analysis results, the number of elements and the number of teeth that guarantee the results are found. And then, the effects of the process parameters such as tool shape and temperature on the thread rolling are investigated. The analysis is carried out using DEFORM-3D. The results show that the flank angle and crest round have an effect on the thread rolling load. It is also shown that temperature have significant effects on the effective strain distribution, rolling load, and crack initiation. The crack initiation is predicted using the Cockcroft-Latham criterion.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.125.2-125.2
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• 2005

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.623-632
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• 2014

In this study, the stability of fishing vessels get some change in accordance with the installation of LED luring lamp in comparison with metal halide luring lamp were investigated. Inclining test for 9.77 ton class of squid jigging and hair-tail angling vessel was performed in order to make a stability evaluation. A performance analysis of the target vessels to the stability on the basis of KST-SHIP program was evaluated. The results were as follows in this study. The stability of the fishing vessel by a metal halide such as LED and the like according to the result obtained by the inclining test is a slightly present difference, and the stability is not affected. The fishing vessel with LED lamp installed satisfies all the stability criteria specified in law and IMO rule. Compared to the metal halide LED lamp the increase of the height of the center of gravity and the initial transverse metacenter was caused. Due to the LED installation, the somewhat wider wind area of the waterline, which appears as a result, does not lead to an actual increase in rolling period. But then it is necessary to be designed on that the LED lamp shape reduces wind pressure area. Because of LED lamp installation, the GM value of vessels is increasing faster rolling cycle so causes a decrease in the sense that the crew is aboard.

• Journal of the Korean Applied Science and Technology
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• v.30 no.1
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• pp.166-172
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• 2013

The purpose of this study is to evaluate the treatment ability of refractory organics in hot rolling precess waste water by redox(reduction and oxidation) reaction. Metal is oxidized in an aqueous solution to generate electron which can reduce water to generate hydroxy radical. These hydroxy radical is very effective to conduct hydrogen abstraction reaction and addition reaction to the carbon - carbon unsaturated link. The surface area of metal alloy reaction material is more than enough to get equilibrium at a single treatment. The efficiency of COD treatment by redox reaction showed maximum at mild pH of pH 7 and pH 6. But it was not effective in acidic atmosphere of pH 3, 4, 5 and basic atmosphere of pH 8 or over. Redox reaction system in much more helpful in a commercial coagulation sedimentation treatment than exclusive system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.518-523
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• 1993

A computer program has been developed for analyzing the two-dimensional unsteady conservation equations for transport phenomena in the ool region of direct rolling with semi-solid metal in order to describe the velocity and temperature, and the solidification process of the semi-solid metal. The energy equations of cooling roll is solved simultaneously with semi-solid metal in order consider heat transfer through the cooling roll. The FDM(finite difference method) and FEM(finite element method) are used in region of pool and roll, respsctively, to reduce computing time and to improve accuracy of calculation. In the present study, influence of solid fraction and casting speed are investigated in a point of view of strip formability with semi-solid metal.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.1
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• pp.43-48
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• 2009

The fatigue crack growth behavior of high strength X80 pipeline steel was investigated with compact tension specimens that crack growth directions were aligned either parallel or normal to the rolling direction of the pipeline. Also, the fatigue crack growth rates for welded joint of X80 pipeline steel were investigated with compact tension specimens that crack growth directions were aligned either parallel or normal to the welding line. The experimental results indicated the fatigue crack growth behavior was markedly different in three zones, weld metal, heat affected zone and base metal of welded joints. There was a trend toward increment in the fatigue life of weld metal and heat affected zone as compared with the X80 pipeline steel.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.4
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• pp.212-219
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• 2001

The fatigue test was carried out to evaluate the fatigue characteristics of fire resistance steel for frame structure and heat affected zone (HAZ) by the one side Gas Metal Arc Welding (GMAW). In this paper, the fatigue crack growth behavior was investigated with the compact tension specimen of base metal and the HAZ according to chemical composition and rolling end temperature, respectively. And the acoustic emission signals obtained from the fatigue test were analyzed by the time-frequency analysis method as a nondestructive evaluation. Main results obtained are summarized as follows; The hardness was appeared softening phenomenon that weld metal and HAZ are lower than that of base metal. Fatigue life of welded specimen was longer than that of base metal. m was 3~4.5 in base metal and 3.8~5.8 in HAZ. The main frequency range of acoustic emission signal analyzed from time-frequency method is different with the range by noise and crack. Also, it could be classified that it was also generated by fracture mechanics of dimple, inclusion etc.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.10 s.241
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• pp.1315-1320
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• 2005

TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/A16061 shape memory alloy(SMA) composite was fabricated by hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with $0\%,\;3.2\%,\;5.2\%\;and\;7\%$ and volume fraction of TiNi alloy fiber, respectively. A fatigue test has performed to evaluate the crack initiation and propagation for the TiNi/A16061 SMA composite fabricated by かis method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also done under both conditions of the room temperature and high temperature. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied.