• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.8
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• pp.855-861
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• 2011

We predict the rolled-strip profile for a 6-high mill using thin rolling theory and a numerical model. In the numerical model, we calculate the distributions of the contact pressures between the rolls and the rolling pressure between the strip and the work roll in the transverse direction using the geometric structure of the 6-high mill and the boundary conditions. We determine the distribution of the rolling pressure in the rolling direction via a thin-foil rolling model using Fleck's theory. We calculate the three-dimensional elastic deformation of the work roll using the pressures of the width and rolling directions. We then obtain the three-dimensional strip profile via the elastic deformation of the work roll during the rolling process. The profile is verified by a thin cold-rolling test and FE simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03a
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• pp.101-109
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• 1996

Mini-mill process which is one of the new steel -marking technologies to be able to produce the hot rolled coils by thin slab caster of ISP(In-Line Strip Production) type, will be completed in the Kwangyang Steel Works of POSCO in August, 1996, SEt-Up Model of finishing mill which consists of 5 stands is the most basic and essential in mini-mill plant. Therefore, the simulation program of Finishing-mill Set-Up model were developed in this research , using new temeprature prediction model, roll gap model and rolling physical model. Using the developed FSU program , pass schedules to produce the strips with target strip thickness of 1.8mm, 2.0mm, 2.3mm, 2.7mm an d3.0mm were also determined respectively.

• Journal of Korea Foundry Society
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• v.13 no.3
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• pp.227-237
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• 1993

• Journal of the Korean Society for Precision Engineering
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• v.7 no.3
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• pp.14-25
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• 1990

A model predicting thermal and wear crown in order to control strip crown and shape has been investigated at the hot roll mill. A basic equation of predicting wear crown was obtained experimentally whereas thermal crown was approximately analyzed by the integral method. The calculated result based on the accumulative model of basic eauation coincides with that measured under the real rolling conditions. The effect of wear corwn is also analyzed by the longitudinal feeding method of the work roll. The high frequency feeding method is recommended in removing local wear effectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.349-358
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• 2004

The strip temperature history of finishing mill process is one of the most important factors to stabilize the facilities and to achieve the better product quality including a better prediction of roll force etc. The ultimate goal of this study is to improve scientific understanding of the finishing mill process in the view of heat transfer science. Finishing mill cooling facilities of KwangYang $\#3$ hot rolling are introduced and heat transfer analyses from FET to FDT are particularly focused in this study Three major tasks are successfully achieved as follows: 1) The temperature Prediction Models are developed. 2) The average absolute error is found to be less then 10 Celsius degree (about $8.5^{\circ}C$). 3) Prediction rate (less then $\bar{+}20$) are $10.2\%$ improved $(80.1\;\rightarrow\;90.3\%)$.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1149-1157
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• 1995

The research for variation of coolant film thickness and separating force has been investigated following the examination for friction profile of work roll and roughness change of strip surface in rolling mill producting actual commercial products. The obtained results are as follows ; (1) Coolant film thickness in cold rolling has been increased relative to the circumferential velocity of work roll, and formation of coolant films has decreased with the smaller diameter of work roll. (2) Separating force is related to the formation of coolant film, and large separating force is needed to the formation of coolant film but it is constant after formation of appropriate film. (3) Wear and roughness alleviation of work roll is larger in bottom-roll than in top-roll on cold surface is larger in the direction of width than in roll direction, and changes of roughness and strip surface hardness rarely occurred after 3 passes.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.101-106
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• 2010

CB100 is one of the channel type products in the steel beam. In this study, rolling process of CB100 is analyzed by 3D FEM simulation and rolling process. FEM simulation result is compared with rolling process data. Also the intermediate & finishing roll stress analysis is carried out and the suitability of the roll through roll stress resultant analysis is evaluated. In order to decrease the roll stress, new pass schedule is developed for stable load balance between intermediate and finishing rolling stand. Therefore new rolling pass schedule is verified by the analysis results of rolling process and roll stress. By the analysis results, the credibility of rolling process analysis was obtained and it was determined that the possibility of roll damage between intermediate and finishing mill was high. So the new pass schedule was developed. Through the result of rolling process and roll stress analysis, it was obtained that the reduction of roll stress and stable load balance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.505-511
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• 1993

The results were obtained with changes according to the surface roughness of work roll and method to make the peak count on the roll in the temper rolling, and factors to affect to the work roll surface in actual rolling machine(ie. Temper mill). Conclusions are as follows. 1. E.D.T(Electro-discharge texturing)roll is more uniform roughness distribution than shot blasted roll and it's life time is two timees longer than that of shot blasted because it has more sine wave roughness. 2. The higher peak count of surface roughness, the more time is necessary to work roll texturing In shot blasting method, Surface roughness is relating to the grit size,impeller speed and hardness of roll material, But is can't control the peak count. 3. In shot blast texturing, Surface roughness of temper rolled strip which is transfered surface roughness of work roll is more ununiform than that of E.D.T roll 4. E.D.T roll has more uniform than the shot blasted roll and has more peak count than that of shot blasted roll. The surface of painted strip to image clarity is superior to that of shot blasted roll because E.D.T roll has more peak count and smooth surface.

• Composites Research
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• v.23 no.3
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• pp.58-63
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• 2010

Tensile and flexural properties and electrical conductivity of MWCNT/epoxy composites with different aspect ratios of MWCNTs were compared. The MWCNT/epoxy mixtures were prepared by mechanical dispersion methods using a homomixer and a three-roll mill, and then composite samples were fabricated by compression molding process. The fractured surfaces of the samples were observed by SEM in order to evaluate the degree of dispersion of MWCNTs. The addition of MWCNTs into epoxy resin improved its tensile strength by 7.0% while its flexural strength increased slightly as compared with the one without MWCNTs. In the case of MWCNTs having highest aspect ratio, the mechanical properties of the composites were decreased. When the contents of CM-95 MWCNTs were varied, maximum of tensile and flexural strengths occurred at 1wt% and 0.5wt%, respectively. From the higher contents than these, tensile and flexural strengths of the composites decreased. Electrical conductivities of in-plane and thought-the-thickness directions of MWCNT/epoxy composites were measured using a two-point probe method. They increased with the increase of the aspect ratios and concentrations of MWCNTs in the epoxy matrix.

• Journal of Korea Foundry Society
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• v.16 no.2
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• pp.124-131
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• 1996

High temperature properties such as hot hardness and thermal fatigue resistance of high speed steel roll of hot finishing mill have been investigated. Two kinds of roll having compositions, Fe-1.75%C-5.9%Cr-1.74%Mo-4.94%V-2.03%W(A specimen) and Fe-2.27%C-8.86%Cr-2.91%Mo-3.92%V-1.86%W(B specimen)were prepared for investigating the microstructure and crack propagation mode. A specimen has greater amounts of $M_7C_3$ type carbides and less amounts of MC type carbides in comparison with B specimen. Hot hardness showed sudden decrease over $400^{\circ}C$, resulting in the hardness decrease of 50% at the temperature of $600^{\circ}C$, and showed little variation with time at $500^{\circ}C$ and $800^{\circ}C$. Thermal crack was developed at $550^{\circ}C$ in A specimen and $600^{\circ}C$ in B specimen.