• Laser Solutions
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• v.16 no.4
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• pp.17-23
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• 2013

The research for the development of roll-to-roll printing process is actively underway on behalf of the existing semiconductor process. The roll-to-roll printing system can make the electronic devices to low-cost mass production. This study is performed for developing the manufacturing technology of the printing roll used in the printing process of electronic devices. The indirect laser engraving technology is used to create printable roll and the printable roll is made out of the chrome coated roll after coating copper and polymer on the surface of steel roll, ablating the polymer on the surface of roll and etching the roll. The 3 dimensional laser scanner and roll rotating systems are constructed and the system control program is developed. We have used the fiber laser of 100 W grade, the 3 dimensional laser scanner and the 3 axes moving stage system with a rotating axis. We have found the optimal conditions by performing the laser patterning experiments and can make the minimum line width of $24{\mu}m$ by using the developed 3 dimensional laser scanner system.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.4
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• pp.135-140
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• 2017

This paper proposes a signal merging algorithm to increase the signal-to-noise ratio (SNR) of a GPS correlator output to estimate the roll angle of a rotating vehicle in a weak GPS signal environment. Rotation Locked Loop (RLL) algorithm is used to estimate a roll angle using the characteristics that the power of the GPS signal measured at the receiver of a rotating vehicle varies periodically. First, delay times are calculated to synchronize GPS signals using satellites' and receiver's positions and the rotation frequency of a vehicle, and then correlator outputs are delayed in time and merged with each other, resulting in the increase of an SNR in a correlator output. Finally, simulations are conducted and the performance of the proposed algorithm is validated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.6
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• pp.779-787
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• 2002

The cooling heat transfer by impinging water spray jets on a rotating roll with a relatively large diameter has been investigated under various experimental conditions with 3 different sizes of flat type nozzle. The local heat transfer coefficients were calculated by finite difference method using measured surface temperatures of the circular cylinder as boundary conditions. Results show that a peak value of the heat transfer coefficient is located at the center of sprayed area and there may be a secondary peak at the downstream. The average heat transfer coefficients on the sprayed area were found to be 10 to 22 ㎾/$m^2$$^{\circ}C$, and were not related to spraying pressure, but approximately linearly to flow rate of sprayed water. Also it is found that increasing the distance from roll to nozzle could improve the cooling efficiency by increasing the sprayed area.

• Journal of KSNVE
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• v.7 no.3
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• pp.499-509
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• 1997

During the process of oxide removal from work rolls in sheet metal manufacture, filamentary brushes frequently exhibit a bouncing or chatter behavior. The dynamics of this phenomenon is investigated through the development of expressions for the non-linear contact stiffness between the brush and the roll. With formulation of simple structural models, the time responses in the presence and absence of friction under random excitation are investigated. Possible solutions for the minimization or avoidance of this bouncing or chatter problem are also suggested.

• Journal of Wind Energy
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• v.9 no.4
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• pp.9-15
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• 2018

In a previous study, a technique for measuring wind speed and direction by using a roll-rotating three-axis ultrasonic anemometer was proposed and verified by wind tunnel tests. In the tests, instead of a roll sensor, roll angle was trimmed to make no up flow in the transformed wind speeds. Verification was done in point of the residual error of the rotation effect treatment. In this study, roll angle was measured from the roll motor encoder and the transformed wind speed and direction on the test section axis were compared with the ones provided to the test section. As a result, up to yaw $20^{\circ}$ at a wind speed of 12 m/sec or over, the RMS error of wind speed was within the double of the ultrasonic anemometer error. But at yaw $30^{\circ}$, it was over the double of the ultrasonic anemometer error. Regardless of wind speed, at yaw $20^{\circ}$ and $30^{\circ}$, the direction error was within the double of the ultrasonic anemometer error. But at yaw $10^{\circ}$ or less, it was within the error of the ultrasonic anemometer itself. This is a very favorable characteristic to be used for wind turbine yaw control.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.1
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• pp.59-69
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• 2001

Ths paper presents an algorithm of detecting eccentricity signal and diagnosing the cause in rolling process. A designed technique uses only the outputs of load cell and tachorreter, which are generally utilized in rolling process, and need not any acklitional sensors. Detecting signals related to eccentricity is done by combining outputs of 6 digital bandPass filters whose center frequency are varied with roll's rotating frequency. A function of diagnosing the cause of occentricity from extracted data having occentricity components is implemented by defining reasonable variables. In order to show validity of an algorithm designed in this paper, simulation was accomplished for three groups. The first is that some portion of roll in the direction of roll circumference is distorted. The second is that rotating axis and roll center is not identical. The third is that composite cause is occmed Simulation results show that every kind of eccentricity can be diagnosed in terms of algorithm proposed.oposed.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.75-81
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• 1999

Roll forming process is simulated with a commercial FEM code LS-DYNA. The rolls are treated as rigid bodies rotating with a constant angular velocity. The strip and the rolls are modeled with 4-node plate elements. It is assumed that the nodes along the front end of the strip move along paths given by sine functions. It is found that the analysis can be applied to the optimal design of forming rolls. With these analyses, it is expected that forming defects can be avoided and process development efforts can be reduced.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.189-205
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• 1996

The twin-roll type strip continuous casting process(or direct rolling process) of steel materials is characterized by two rotating water cooled rolls receiving a steady supply of molten metal which solidifies onto the rolls. A solidification analysis of molten metal considering phase transformation and thermofluid is performed using finite diffefence method with curvilinear coordinate to reduce computing time and molten region analysis with arbitrary shape. An enthalpy-specific heat method is used to determine the temperatures inthe roll and the steel. The temperature distribution of cooling roll is calculated using two dimensional finite element method, because of complex roll shape due to cooling hole in rolls and improvemnt accuracy of calculation result. The energy equaiton of cooling roll is solved simultanuously with the conservation equaiton of molten metal in order to consider heat transfer through the cooling roll. The calculated roll temperature is compared to experimental results and the heat transfer coefficient between cooling roll surface and rolling material(steel) is also determined from comparison of measured roll temperature and calculated temperature.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.12
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• pp.1017-1023
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• 2007

This study is intended to analyze the effect of thin ink-film thickness around rotating printing roll on the printing quality in the gravure printing process which is used for making electronics circuit like a RFID tag with a conductive ink. The present work numerically estimates the film thickness around rotating roller partially immersed in ink for which the volume of fluid (VOF) method was adopted to figure out the film formation process around rotating roller. Parameter studies were performed to compare the effect of ink properties (viscosity, surface tension), operating condition (roller rotating speed, initial immersed angle) on the film thickness. The result indicates that the film thickness has a strong dependency on the rotating speed, while the surface tension has negligible effect.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2279-2284
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• 2007

This study is intended to analyze the effect of thin ink-film thickness around rotating printing roll on the printing quality in the gravure printing process which is used for making electronics circuit like a RFID tag with a conductive ink. The present work numerically estimates the film thickness around rotating roller partially immersed in ink, for which the volume of fluid (VOF) method was adopted to figure out the film formation process around rotating roller. Parameter studies were performed to compare the effect of ink viscosity, surface tension, roller rotating speed, immersed angle on the film thickness. The result indicates that the film thickness has a strong dependency on the fluid viscosity, while the surface tension has negligible effect.