• Journal of Power System Engineering
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• v.16 no.6
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• pp.52-58
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• 2012

Roll forming process is one of the most widely used processes in the world for forming metals such as a furniture drawer guide or an up and down slide guide. It can manufacture goods of the uniform cross section on a large scale throughout the continuous processing. In the domestic design and manufacture, roll forming process for production is taking most of the method of 2-point under rail slide. However, this method is vulnerable to the structural strength and stiffness is not suitable for high load conditions. Therefore, through systematic study of high load, low noise 3-point ball type of under rail slide its own design and manufacturing technology is the need to build. In this paper, to make center member of 3-point ball-type under rail slide for the refrigerator doors, the roll forming modeling and simulation are performed. Tensile test is performed about SCP-1 1/2H for determine the mechanical properties of materials. Modeling and simulation of roll forming is used MSC.MARC software of a dedicated analysis program used by rigid plastic finite element method. Interference between the roll and the final shape are predicted from the results of the simulation.

• Journal of the Korean Society for Precision Engineering
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• v.2 no.3
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• pp.47-58
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• 1985

The study is concerned with the analysis of the required loads and torque in the Three-Roll Power Spinning Process by using the Method of Force Polygon Diagram. Experiments are carried out using pure lead billets at room temperature. The radial force, the axial force and the torque occurring during the process are calculated theoretically and are compared with the experimental data. An approximate load distribution is known by the Force Polygon Diagram.

• Transactions of Materials Processing
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• v.3 no.1
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• pp.63-83
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• 1994

In this paper, the slab method have been applied to investigate the strip casting process in which hot coil is produced from molten steel directly. In the twin roll strip casting process, molten steel supplied by the nozzle cools and solidifies due to the heat extraction effect of the rolls and hot rolling of the solidified shell takes place simultaneously. The analysis of hot rolling has been carried out by using the existing results of solidification analysis for the twin roll strip casting process. The current slab method provides basic design data such as roll separation force, rolling torque, rolling power as well as end dam separation force which are required to design strip caster. The effect of friction on the basic process parameters are investigated also. It is shown that the use of appropriate friction coefficient is important and that the characteristics of hot rolling in the twin-roll strip casting process is quite different from the conventional hot rolling processes.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1155-1165
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• 1990

A new method of predicting effect of rolling parameters on roll pressure, roll force, and power and energy consumptions in hot strip rolling is presented. The method is based on approximate solutions for velocity, strain rate, and stress distributions in the roll gap. The degree of approximation was examined by the finite element solutions. The theoretical predictions were compared with experimental data from hot rolling of steel strip and steel plate.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.498-500
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• 2004

QPSK (Quaternary Phase Shift Keying) will be adopted as the modulation of HRIT (High Rate Information Transmission) which is transmitted to COMS (Communication, Ocean and Meteorological Satellite) through HPA (High Power Amplifier) in ground segment. Due to the nonlinearity of HPA, IMD (Inter-Modulation Distortion) of multi-carrier signals and PAPR (Peak-to-Average Power Ratio) of modulated HRIT must be considered to estimate the output power of HPA. In this paper, we measured the PAPR to various the roll-off factor of RRC (Root Raised Cosine filter) which is filtering the modulated HRIT signal for reducing ISI (Inter-Symbol Interference) and bandwidth. It was found that the minimum PAPR is 2.78dB at 0.5 of roll-off factor for scrambled data. It's 2.78dB of P APR will be in output power selecting in COMS earth station.

• Journal of Power System Engineering
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• v.6 no.3
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• pp.42-48
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• 2002

Velocity change of crashed vehicle has been applied to assess the safety of passenger and degree of impact severity widely. In this study, 1 D crash analysis and 2 D crash analysis were performed for velocity change of crashed vehicle with HVE 2D, and factors used for these analysis are weight, C.G, roll resistance, stiffness and brake force which influence on velocity change of crashed vehicle. According to results, the velocity change of crashed vehicle was influenced by weight, center of gravity stiffness and brake force but not roll resistance.

• Journal of Mechanical Science and Technology
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• v.18 no.5
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• pp.762-769
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• 2004

An analytical approach is presented to investigate the deformation characteristics of billets in a continuous billet mill using power driven horizontal stands and idle vertical stands. The analysis is validated by comparison to the experimental results in a previously published work. The analytical results have shown that, apart from the problems of slip and buckling of billet, there are some shortcomings involved in this method. Compared to conventional rolling with all driven stands, the roll load for idle vertical stands and the rolling torque for horizontal stands are almost doubled. The billet is severely stressed within the roll-bite of idle vertical stands and the overall rolling power has increased by one third of that for conventional rolling. Theseshortcomings impair the feasibility of industrial application of idle vertical stand rolling method.

• Korean Journal of Materials Research
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• v.18 no.1
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• pp.32-37
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• 2008

The electrical, optical, structural and surface properties of an indium tin oxide (ITO) film grown on a flexible PET substrate using a specially designed roll-to-roll (R2R) sputtering system as a function of the DC power, $Ar/O_2$ flow ratio, and rolling speed is reported. It was observed that both the electrical and optical properties of the ITO film on the PET substrate were critically dependent on the $Ar/O_2$ flow ratio. In addition, x-ray diffraction examination results showed that the structure of the ITO film on the PET substrate was an amorphous structure regardless of the DC power and the $Ar/O_2$ flow ratio due to a low substrate temperature, which was maintained constant by a main cooling drum. Under optimized conditions, ITO film with resistivity of $6.44{\times}10^{-4}{\Omega}-cm$ and transparency of 86% were obtained, even when prepared at room temperature. Furthermore, bending test results exhibited that R2R-grown ITO film had good flexibility which would be applicable to flexible displays and solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.380-381
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• 2007

This paper reports on the deposition conditions and properties of ITO films used as electrode layer in a organic light emitting diodes on a PET substrate. The deposition technique employed was specially designed roll-to-roll sputtering. The oxide was deposited at room temperature in an argon and oxygen plasma on a transparent conducting ITO layer on a PET film. The influence of deposition parameters such as DC power, working pressure and oxygen partial pressure has been investigated, in order to obtain the best compromise between a high deposition rate and adequate electro-optical properties. Electrical and optical properties of ITO films were analyzed by Hall measurement examinations with van der pauw geometry at room temperature and UV/Vis spectrometer analysis, respectively. In addition, the structural properties and surface smoothness were measured by x-ray diffraction and scaning electron microscopy, respectively. From optimized ITO films grown by roll-to-roll sputter system, good electrical$(6.44{\times}10^{-4}\;{\Omega}-cm)$ and optical(above 86 % at 550 nm) properties were obtained. Also, the ITO films exhibited amorphous structure and very flat surface beacause of low deposition temperature.

• Transactions of Materials Processing
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• v.20 no.3
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• pp.243-249
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• 2011

In this study, an approach designed to compute high temperature friction coefficients for SCM 435 steel through a pilot hot rolling test and a finite element analysis, is proposed. Single pass pilot hot flat rolling tests with reduction ratios varying from 20 to 40% were carried out at temperatures ranging from 900 to $1200^{\circ}C$. In the proposed approach, the friction coefficient is calculated by comparing the measured strip spread and the roll force with the simulation results. This study showed that the temperature and reduction ratio had a significant influence on the friction coefficient. As both material temperature and reduction ratio become higher, the friction coefficient increases monotonically. This finding is not in agreement with the Ekelund model, which is widely used in the analysis of the hot rolling process. In the present work, the friction coefficient at a reduction ratio of 40% was found to be 1.2 times greater than that at a reduction of 30%. This higher friction coefficient means that an increment of the roll thrust force is expected at the next stand. Therefore, a roll pass designer must understand this phenomenon in order to adjust the reduction ratio at the stands while keeping the driving power, the roll housing structure and the work roll strength within the allowable range.