• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.329-332
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• 2005

Cross rolling process is one of incremental forming processes to form an axi-symmetric shaped metal component. It can be classified into two types according to the shape of dies, which are a drum type (roll type) and a plate type (straight type). It can also be classified into a wedge type and a ramp type processes according to deformation characteristics of a material. The ramp type die is applied to plate type cross rolling process in cold forming process for forming of teeth of gear or bolt, while the wedge type die is generally utilized to drum type and plate type cross rolling processes in hot forming process. A shape of the ramp type die is usually same as final shape of a product at every section of a progressing direction, while the shape of the wedge type die has different shapes in a progressing direction. In this paper, a rolling of neck part in a ball stud component has been carried out using the plate type cross rolling process with a ramp shaped die. Forming characteristics have been performed using finite element analysis in order to obtain a proper preform for the ramp type plate cross rolling process.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1457-1465
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• 2011

The saloon light is the device that can offer convenience and comfort to the driver and passenger when the train is operated at night or in the tunnel. Generally, The fluorescent type saloon for the rolling stock have been used, but the problems that are short life and the generation of heat have been brought about because the saloon lihgts of rolling stock are supposed to operated continuously long time, and high power consumption. So, the development of new type of saloon lights has been requested in order to solve these problems. And recently the various LED type lights have been developed and LED type saloon lights for rolling stock also has been developed. Therefore, we survey the characteristic, function and needed condition of the LED type saloon lights for rolling stock, and analyze the good and bad point, and then research the complement of weak point. We want to find the direction and develop the design of future LED saloon light type.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.40-47
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• 2011

Mobile harbor which is a novel concept of ocean transportation to bring the containers from the cargo ship waiting on the ocean away is being focused now. To provide the mobile harbor with the stable loading/unloading condition, it is necessary to develop the oscillation mitigation technologies such as anti-rolling system. Anti-rolling system using AMD(Active Mass Driving) has merits that it can handle the disturbances more actively and mitigate the rolling oscillation faster than other type anti-rolling system. However, rack-and-pinion type AMD has problems such as big friction noise from gears and motor, wear and tear, and continuous maintenance. In this paper, novel anti-rolling system using Maglev type AMD for mobile harbor is suggested in order to resolve the problems caused by the friction. This novel anti-rolling system doesn't make any friction because it supports the moving mass by using magnetic levitation force and moves it by using propulsion force from the linear motor. The demo system of the novel anti-rolling system using maglev type AMD has been developed in order to investigate its feasibility. This paper presents the procedures and results of development of this demo system.

• Tribology and Lubricants
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• v.16 no.1
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• pp.9-14
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• 2000

It has been cleared in previous author's paper that the fatigue life before the pitting on the rolling contact surface with lubricant are influenced by the wear amount. In this study, the wear type has been clarified when wear amount is extremely large such as the case without lubricant. The test of rolling contact fatigue has been conducted under two different of herzian pressures and three different of slide ratios without lubricant. In addition, residual stress and half-value breadth using X-ray diffraction on worn surface have been measured as well as the wear amount. The results show that the pitting type wear by rolling contact fatigue has not been occurred when the wear amount is considerably large. Thus this type of wear has been deduced by the fatigue wear depending on delamination theory.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.04b
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• pp.126-132
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• 1996

A laboratory scale hot strip rolling wear simulator(HRWS) was developed for the purpose of investigating the tribological phenomena occurred in production hot strip rolling mills. The HRWS' main parts are the electric heater, the mechanical descaler, tandem type 2-4Hi rolling mill stands, the cooling chamber, the tension controller and coiler. By simulating the tribelogical phenomena in rolling process at laboratory, wear patterns, cracks, cat-ear wear, black film, effect of hot rolling oil lubrication, etc. were reproduced, and discussed on the performace of simulator.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.189-195
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• 2007

The purpose of this study was to analyze the effects of shoes with curved out-sole on the pressure, reaction force(sum of pressure) on foot and relations between the rolling speeds and pronation of foot. The foot pressure, reaction force and pressure center on the foot surface of shoe were measured with NOVEL padar system, and 3 type shoes were used to compare the position and speed of pressure center and the foot reaction force, which were s(target) shoe with soft cushions in middle part of out-sole and curved out-sole, m shoes with two type- soft, hard, hardness out-sole and curved out-sole and n shoes with flat out-sole. The subjects were 13 female university students, had weared the 3 type shoes for 6 weeks on two-weeks shifts for adaptation before experiment and put on 3-type shoes repeatedly and randomly and walked on treadmill with 3.5km/h and 80 steps/min. The data were captured with 30Hz and readjusted with 5kgf threshold reaction force. The results can be summarized as follow. 1. There were no difference in maximum reaction force on initial contact period and total foot impact, but statistical difference in maximum reaction force on takeoff period : s, m, n in ascending order. 2. There were some difference in rolling speeds for support periods. At initial contact, the rolling speed of s shoes was fastest but at periods between first and second maximum reaction force, that of m shoes fastest. 3. There was a negative relation between rolling speeds and the length of lever arm on initial reaction force related to pronation. It seems shoes with various curved shapes and hardness could make effects on the rolling features and the rolling speed also have some relationships with walking efficiency, absortion of impact and pronation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.163-171
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• 1999

The abnormal grain coarsening in wire rolling induces detrimental defects, such as jagged size tolorance, severe bending after heat treatments and drawing troubles, in the following secondary processes. Neishi et al observed that there is a band type region where grain coarsenting occurs in the plastic strain vs. deformation temperature plot. Based on the finding, we have investigate whether grain sizes and ferrite volume fractions are correlation to deformation strain with three kinds of wire rod diameters as for the different average deformation conditions. The samples were chosen from the No.2 Wire Rod Mill of POSCO where 3-roll type of finishing mill stand are used. It was found in the present work that the grain size and ferrite volume fraction of the rolled and cooled microstructure were changed with rolling reduction and rolling temperature. Abnormally grown grains at various observed points were also found. To have homogeneously fine grains of microstructure from the No. 2 Wire Rod Mill, it will be easier to control finish rolling temperature at around 750$^{\circ}C$ rather than to find another rolling schedule.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.117-122
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• 2017

In this study, we studied the ride quality considering the deterioration effects of the three type couplers (single, double, and ring types) for EMUs. In order to know the impact occurred when an urban transit vehicle is under breaking, we tested the conditions of the service brake and the emergency brake. Normal coupler models without any slack showed similar dynamic performance results under all breaking conditions. But if the couplers become old, the initial pre-stresses are removed because of permanent compressive deformation in rubber. For three types of the old coupler models without the initial pre-stress, we evaluated dynamic performances of each type. As the results, the maximum and average acceleration levels of the double type and the ring type were similarly low in all conditions. But the accelerations of the single type coupler was high when compared to those of the double and ring types. In addition, Jerk value of the single type model associated with ride quality was high up to 15 times to the ring type in condition of the service braking in empty vehicle weight. Jerk value of the double type model was high up to 6 times to the ring type.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.200-207
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• 1999

To increase dimensional accuracy of strip width, model to compensate width spread during roughing mill has been developed. To measure the amount of width spread during the production rolling more precisely, special roughing rolling procedures for the horizontal rolling and dog-bone rolling were designed in the actual production mill. From the operational data analysis, it is known that the prime factors influencing on the width spread were strip width, strip thickness, edging amount, number of pass and type of edger roll etc., Based upon the statistical analysis of rolling data, new models which can predict width spread during horizontal rolling and dog-bone rolling were developed and tested on the actual processing conditions for the reliability. The application test showed that newly developed model gave fairly accurate predictions on the width spread during roughing passes.

• Journal of Korea Foundry Society
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• v.3 no.2
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• pp.92-99
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• 1983

This study has been carried out to investigate into the difference of rolling life and rolling wear characteristics for various gray cast iron under unlubricated dry rolling condition by amsler type wear test with 9.09% sliding.The results obtained from this study are summerized as follows: 1) It has been found that the amount of rolling wear id decreased when tensile strength and hardness are low, and then the rolling life up to generation of abnormal wear is conspicuously increased. 2) At the given condition the amount of rolling wear has been found to decrease as carbon equivalent of gray cast iron increases and resistance of crack propagation is an important factor on improvement of wear characteristics. 3) The amount of rolling wear is increased with increasing rolling revolution and wear of gray cast iron under dry rolling condition is characterized by three modes; initial wear, stationary wear and abnormal wear. 4) It has been found that the amount of rolling wear is increased with increasing maximum compressive stress and extremely increased when maximum compressive stress is over 59.1kg.f/mm.