• Proceedings of the KSR Conference
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• 1998.11a
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• pp.512-521
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• 1998

The roll characteristic of railway vehicle is an important factor that affects the roll-over of vehicle and lateral ride comfort of passenger. Generally the roll characteristics of railway vehicle is defined by the term of roll-coefficient, s, which represents the ratio of incline or carbody to that of rail-cant. The limit values of roll coefficient recommended in UIC Bre 0.4 for coach without pantograph and 0.15 for vehicle with pantograph. The roll coefficient can be calculated by VAMPIRE that is the well-known commercial software for analysis of dynamic behavior of railway vehicle. The value of roll coefficient is effected by height of gravity center of carbody, stiffness of primary and secondary suspension and etc. The calculated roll-coefficient for electric locomotive and passenger coach is 0.12 and 0.77 respectively, The additional equipment such as anti-roll bar is considered in order to decrease roll-coefficient of passenger coach. In relation to roll characteristics, the analysis for roll-over due to wind is a1so performed. The results show that roll-characteristics affect the roll-over of vehicle.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.115-118
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• 1997

Recently, hot rolling oil lubrication technology is required to face with the new environments such as the rapid introduction of high wear resistent high speed steel roll the development of continuous hot rolling technology. In the hot strip mill, according to rolling and quality required conditions are constrict, Roll material of hot rolling finishing stand is changing Hi-Cr Roll to High Speed Steel [HSS] Roll. The problem of HSS Roll of roll force and strip scale defects are increasing in hot strip mill, So we have tested HSS Roll in hot rolling simulator as rolling condition, rolling speed, draft, hot oil concentration. To reduce roll force and prevent scale defects. We get some merit rolling force, rolling torque, roll wear reduction, roll and strip surface roughness and hot rolling critical oil concentration 0.4%. Finally we are going to investigate the effect of hot rolling oil of on rolling with HSS Roll.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.11
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• pp.1742-1748
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• 2014

This study investigated the quality characteristics of commercial rice flour (CRF) and rice flours prepared by different milling methods for sulgidduk. For particle distribution, dried rice flour after the 1st roll mill using a pin mill showed a particle size of greater than $710{\mu}m$, whereas a particle size less than $250{\mu}m$ accounted for 48% of whole rice flour. This proportion was higher than CRF after the 2nd step roll mill. Crude protein, lipid, and ash contents were significantly highest in 1st roll mill samples. For color, roll & pin made up of many small particles showed a high L value. CRF and roll & pin showed significantly higher starch damage and water-holding capacity, whereas pasting temperature, peak viscosity, and setback of RVA pasting characteristics were lower than 1st roll mill. When rice cakes were made from three kinds of rice flour, roll & pin was not significantly different compared to the CRF. However, rice cakes made with 1st roll milled rice flour showed rough crumb and crust. Rice cake made with roll & pin or CRF showed similar characteristics for texture. In the quantitative descriptive analysis, rice cake made with roll & pin showed better appearance, flavor, taste, texture, and overall acceptability than CRF and 1st roll mill. Therefore, rice flour prepared by roll & pin could be applied to sulgidduk with high quality.

• 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.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.614-618
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• 2002

In hot strip mills, Portable Roll Scanner (the portable roll surface temperature and profile measuring device) can be used to calibrate on-line Process models for strip crown and flatness by measuring the thermal expansion and wear profile of the rolls. And the surface temperature measurement can be used to optimize the roll cooling system. Portable Roll Scanner consists of the measuring device, which has two contact inductive distance transducers for roll profile measurement and one infrared Pyrometer for surface temperature measurement, and computer-based controller that is equipped with the measuring device. By the wireless data communication, the data is transferred to the memory of notebook for further analysis. After roll extraction from mills, Portable Roll Scanner measure the roll profile and surface temperature simultaneously along the work roll face and display the results in the TFT color monitor of notebook. Portable Roll Scanner is useful at mill-side and roll grinding shop.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.69-80
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• 1993

It is important to prevent roll failure in hot rolling process for reducing maintenance coat and production loss. Roll material and rolling conditions such as the roll force and torque have been intensively investigated to overcome the roll failures. In this study, a computer roll life prediction system under working condition is developed and evaluated on IBM-PC level. The system is composed and fatigue estimation models which are stress analysis, crack propagation, wear and fatigue estimation. Roll damage can be predicted by calculating the stress anplification, crack depth propagation and fatigue level in the roll using this computer model. The developed system is applied to a work roll in actual hot rolling process for reliability evaluation. Roll failures can be diagnosed and the propriety of current working condition can be determined through roll life prediction simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.229-232
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• 2003

In the roll forming process, a sheet or strip of metal is continuously and progressively formed into a desired cross-sectional profile by feeding it through a series of forming roll. Accordingly, it is important to maintain the material properties of the initial sheet and deform uniformly during the roll forming. The roll forming process was estimated in consideration of some factors such as material properties, strip thickness, roll diameter, roll velocity, and the deformation of the material that influence the forming length. The hydroforming technology has been recognized as a new technique in manufacturing industry, especially in automotive industry. The formed pipe in used in hydroforming process is manufactured by the roll forming. The formability during hydroforming is very sensitive to the state of pipes which are made by roll forming. Particularly the amount of hardening during roll forming affects the formability. Therefore, it is necessary to design the optimum roll flower to reduce the local hardening. In this paper, optimum roll flower which has uniform strain distribution through sheet width was obtained by comparing strain distribution in various roll flower. Finite element analysis(FEA) is performed to estimate the strain distribution related to hardening by roll forming. A numerical analysis is carried out by SHAPE-RF.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.308-312
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• 1999

Developed the model equations which calculate roll force, roll power during hot rolling in real time. The variables which mainly effect on the roll force, roll power are shape factor, reduction, roll diameter, roll velocity, strip inlet temperature, carbon content of strip and strip-roll contact friction coefficient. Among these variables roll diameter, roll velocity, inlet temperature, carbon content and friction coefficient can be excluded in interpolated model equation by introducing equation of die force(F'), power(p') of the frictionless uniform plane strain compression which can be calculated without iteration. At the case of coulomb friction coefficient of 0.3, we evaluated coefficient of polynomial equations of {{{{ { F} over {F' } }}}}, {{{{ { Pf} over {Pd }, { Pd} over {P' } }}}} from the result of finite element analysis using interpolation. It was found that the change of values of {{{{ { F} over {F' }, { P} over {P' } }}}} with the friction coefficient tend to straight line which slope depend only on shape factor. With these properties, developed model equations could be extended to other values of coulomb friction coefficient. To verify developed roll force, roll power model equation we compared the results from these model equation with the results from these model equation with the results from finite element analysis in factory process condition.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.73-85
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• 1997

The rolling force and roll deformation behavior in the twin roll type strip continuous casting process has been computed to estimate the thermal charcteristics of a caster roll. To calculation of rolling force, the relationship between flow stress and strain for a roll material and casting alloy are assumed as a function of strain-rate and temperature because mechanical properties of a casting materials depends on tempera- ture. The three dimensional thermal dlastic-plastic analysis of a cooling roll has also been carried out to obtain a roll stress and plastic strain distributions with the commercial finite element analysis package of ANSYS. Temperature fields data of caster roll which are provided by authors were used to estimated of roll deformation. Roll life considering thermal cycle is calculated by using thermal elastic-plastic analysis results. Roll life is proposed as a terms of a roll revolution in the caster roll with and without fine failure model on the roll surface. To obtain of plastic strain distributions of caster roll, thermomechan- ical properties of roll sleeve with a copper alloy is obtained by uniaxial tensile test for variation of temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.499-504
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• 1993

To find a way for establishing work roll initial crown according to roll conditions, computer simulation for predicting plate crown in plate mill is done and effects of roll conditions on plate crown is analysed. Roll gap profile and plate crown are measured to be compared to the calculated values. As a result,a regression equation to establish work roll initial crown according to roll cooditions such as backup roll diameter, backup roll crown and work roll crown is obtained.