• 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.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.173.2-173.2
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• 2005

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.325-328
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• 1997

In this paper the modeling and control of a twin roll strip caster is investigated. Mathematical models for the strip casting process are obtained by analyzing five critical areas such that the molten steel level in the pool, solidification process, roll separating force and torque, roll dynamics including hydraulic actuators, and roll drive system. A two-level control strategy is proposed. At lower level, three local subsystems are independently feedback-controlled by suitable local controllers which perform well to the behaviors of each subsystem. They are a variable structure control of the molten steel level in the pool, an adaptive predictive control of the roll gap which is directly related to the strip thickness, and an $H^{\infty}$ control of the roll drive system. At higher level, all reference signals to the lower level subsystems are generated by an optimal controller in the perspective of regulating the strip thickness and roll separating force. Simulations are provided..

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.384-388
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• 1997

Recently,direct rolling process has been drawing increasing interests because production cost be greatly reduced by eliminating subsequent hot rolling processes. Such a process has been characterized to prosuce thin steel strip (thickness 1~5mm) directly from molten metal and to skip over the conventional hot rolling processes. However, since there are several process parameters, which affect the quality of product,and their relationship between the parametersare very complex,it is therefore very difficult to realize the process design and the quality control. To overcome these difficulties quantitative relationship between the parameters are investigated through a numerical analysis. Form these results, it is found that solidification final point is the most important paramter which is critical to quality of the strip. Also,the multiple regression model is obtianed to determine their relationship from the solidification final point and roll separating force which can be easily estimated

• Journal of the Korean Society for Precision Engineering
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• v.8 no.4
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• pp.33-40
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• 1991

The decrease in surface roughness of work roll and steel strip in cold rolling of low carbon steel strip has been investigated by working distance, materials, total separating force and total reduction ratio. The main results are as follows; For the same lubricating conditions. 1) The changing of surface roughness of steel strip were similar to work roll. The transcription ratio is in inverse proportion to the carbon content of steel strip. 2) The surface roughness of steel strip is hardly change according to changing of total separating force and total reduction ration. 3) The wear of work rolls surface is more rapid in that case of continuous casted steel strip than ingot casted steel strip. The aluminium content dull powder adhere on the rolls surface, and so. It makes the mirror surface of work roll accelerate.

• Journal of Institute of Convergence Technology
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• v.7 no.2
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• pp.1-5
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• 2017

The rotating electrodynamic wheel over a conductive plate produces thrust force as well as normal force. Specially, separating the conductive plate and spacing apart each part, the lateral stability of the rotating wheel is guaranteed due to the restoring force into neutral position. In this paper, the force characteristics of the electrodynamic wheel rotating over the conductive plate is analyzed using the finite element tool. First, the dominant parameters are identified considering the geometric configuration and the operating condition. And the sensitivity for the parameter deviation is quantified for the high force density. The above topology can be applied as an actuating principle for inter-city train as well as contact-free transfer device.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1055-1060
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• 2001

Springing phenomena of ships is introduced with its concept, research history and approach methodology. Being a hydroelasticity problem, non-linear vibration and stochastic process, springing was formulated and modeled in vibration point of view separating hydrodynamic force into system properties and excitation force. Both RAO and response spectrum as well as wave spectrum were presented as a case study of springing analysis for a flexible vessel with wide breadth. The effect of advance speed, heading angle and loading condition were investigated as parametric study. The results and observations showed availability of analysis for the prediction of the ship springing behavior.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1453-1457
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• 2003

The pantograph for Korean High Speed Train was developed by home-grown technology. In this study, a system to measure the contact force of pantograph is developed and installed on the prototype high speed train, Contact force prevents the pantograph from separating from the catenary. However, excessive contact force causes rapid erosion of catenary. The contact force can be divided into lift force and spring force. Contact force measurement is conducted while the train runs on the test track. The lift force is measured by the load cell on the roof separately and combined with the spring force of pan-head to form the contact force. Measured results show that the contact force of the pantograph of Korean High Speed Train is below the upper limit regulated by the high speed train standards. The contact force measuring system provides data to evaluate safety of the catenary system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.11
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• pp.3454-3462
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• 1996

Compared to a full three dimensional FEM, the Slab-FEM hybrid method reduces the required computation time distinctly and it can be applied to the analysis of a shape rolling process. However, the method is somewhat approximate and predictions by the method contain certain inaccuracies. In the present investigation a parameter called T-factor was introduced to compensate the inaccuracies of the method and proper values of the parameter were estimated for different widths of bars and reduction ratios. Then, the method was applied to analyze cold and hot rollings of rectangular bars and predicted results were compared to those of experiments. Nonuniform distributions of temperature in the bars were predicted by utilizing the temperature equation obtained for a semi-infinite solid under radiation and convection boundary conditions. It was found out that accuracies of spread and roll separating force predictions could be enhanced by using proper values of the T-factor.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.469-472
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• 2008

As recycled fine aggregate manufacturing technology with exceeding in economical efficiency, reduction efficiency of environmental load and quality improvement effect of recycled fine aggregate, it is to develop dry manufacturing system composed specific gravity separator of high-speed rotation impact type and centrifugal Force Powder Collector, etc. in this study. And it is to verify performance with evaluating quality of recycled fine aggregate. In consequence, it is identify that performance improvement effect of recycled fine aggregate by crushing recycled fine aggregate according to high-speed rotation impact, separating and collecting powder and minuteness dust according to centrifugal Force and mass defect, separating and reclaiming minuteness sand to mass defect.