• 한국정밀공학회지
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• 제32권10호
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• pp.897-902
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• 2015

This study reports on a uniform resin coating method by using a doctor blade type dispenser. For high productivity, continuous imprint-lithography has been studied, and developed fabrication systems are used in several applications such as anti-reflection films, dry adhesives, and water collecting surfaces. In the continuous fabrication field, researchers have typically focused on patterning and demolding procedures. During the roll-to-roll fabrication process, however, the uniform resin coating process is also important in order to obtain a high quality product, which can be evaluated by uniform thickness, precise geometric expressions, and a thin residual layer. To achieve these, a doctor blade type dispenser was designed and fabricated. As a result, thickness of coated resin was well controlled by modulating the flow rate of the resin and blading gap. In addition, a very thin layer coating process (${\sim}10{\mu}m$) was achieved by softly contacting the blade on the substrate.

• 한국정밀공학회지
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• 제30권12호
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• pp.1303-1312
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• 2013

We report an ultra-precision lathe designed to machine micron-scale features on a large-area roll mold. The lathe can machine rolls up to 600 mm in diameter and 2,500 mm in length. All axes use hydrostatic oil bearings to exploit the high-precision, stiffness, and damping characteristics. The headstock spindle and rotary tooling table are driven by frameless direct drive motors, while coreless linear motors are used for the two linear axes. Finite element method modeling reveals that the effects of structural deformation on the machining accuracy are less than $1{\mu}m$. The results of thermal testing show that the maximum temperature rise at the spindle outer surface is approximately $0.5^{\circ}C$. Finally, performance evaluations of the error motion, micro-positioning capability, and fine-pitch machining demonstrate that the lathe is capable of producing optical-quality surfaces with micron-scale patterns with feature sizes as small as $20{\mu}m$ on a large-area roll mold.

• 한국정밀공학회지
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• 제28권10호
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• pp.1131-1140
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• 2011

A new rotary gravure-offset printing unit is constructed by paralleling a gravure plate cylinder, a blanket cylinder and a impression roller. A Muti-Unit Gravure-Offset Printing Press(MUGOP) equipped with a series of the 3 printing units is utilized for roll-to-roll fine printing. Its core technology is precise over-piling printing of fine patterns. The severe problems of 'slurring' and 'doubling' in typical offset printing are unavoidable, which can be eliminated by applying a soft pad-type blanket cylinder and the unique 'true rolling' technique. Nip pressure between the blanket cylinder and the plate cylinder is measured by the constant pressure control system which equipped with load cells attached on the cylinders' axes. The running circumference of the blanket cylinder is increased to reach the same circumference of the plate cylinder as the pressure increasing, so that the specifications of the blanket cylinder is determined by the relationships of its shore hardness, diameter and nip pressure. When a softer blanket is used, a blanket cylinder of smaller diameter could give higher nip pressure. Realization of the true rolling technique on the MUGOP makes multilayer printing possible as well as fine printing in printed electronics.

• International Journal of Control, Automation, and Systems
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• 제4권2호
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• pp.255-270
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• 2006

In this paper, a design method of nonlinear autopilot for ship-to-ship missiles is proposed. Ship-to-ship missiles have strongly coupled dynamics through roll, yaw, and pitch channel in comparison with general STT type missiles. Thus it becomes difficult to employ previous control design method directly since we should find three different solutions for each control fin deflection and should verify the stability for more complicated dynamics. In this study, we first propose a control loop structure for roll, yaw, and pitch autopilot which can determine the required angles of all three control fins. For yaw and pitch autopilot design, missile model is reduced to a minimum phase model by applying a singular perturbation like technique to the yaw and pitch dynamics. Based on this model, a multi-input multi-output (MIMO) nonlinear autopilot is designed. And the stability is analyzed considering roll influences on dynamic couplings of yaw and pitch channel as well as the aerodynamic couplings. Some additional issues on the autopilot implementation for these coupled missile dynamics are discussed. Lastly, 6-DOF (degree of freedom) numerical simulation results are presented to verify the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.106.1-106
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• 2001

American options no doubt is invariably more popular than European options, due to the fact that it gives the owner the option to exercise a contract before and up to the expiration date, unlike an European option, which only allows the owner to exercise a contract on the date of expiration. Owing to its popularity, many methods like the binomial numerical method and the pseudo American method have been devised for computing of the value of the American options. The aim of this research is to develop an effective 3-dimensional visualization for American option portfolio based on the Geske-Roll-Whaley model. It is obvious that it is extremely tedious and unadvisable for researchers to interprte chunks of data by looking at graphs or pie charts, which are simple but not effective for analyzing important dta. Hence, the generation of the Geske-Roll-Whaley ...

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권4호
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• pp.409-421
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• 2016

Container ships are prone to move at a greater speed compared to other merchant ships. The slenderness of the hull of container vessel is for better speed, but it leads to unfavorable motions. The pitch and roll are related and sometimes the vessel might be forced to parametric roll condition which is very dangerous. A fin attached to the ship hull proves to be more efficient in controlling the pitch. The fin is fitted at a lowest possible location of the hull surface and it is at the bow part of the ship. Simulations are done using proven software package ANSYS AQWA and the results are compared. Simulations are done for both regular and irregular seas and the effect of fin on ship motion is studied. P-M spectrum is considered for various sea states.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.793-798
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• 1993

In this study the attitude control of the KOREASAT is investigated. The KOREASAT is a geostationary satellite and its 3 attitude angles, namely, roll, pitch and yaw angles, are stabilized by using the 3-axis stabilization technique. In the pitch control loop, the pitch attitude angle received from the earth sensor is processed in the attitude processing electronics by using PI type control logic, and the control command is sent to the momentum wheel assembly to generate the control torque by varying the wheel rate. The roll/yaw attitude control is performed by activating a magnetic torquer or by firing appropriate thrusters. The magnetic torquer interacts with the earth magnetic field to produce the control torque, and the thrusters are used to control the larger roll attitude errors. In this study dynamic modelling of the satellite is performed. And the earth sensor, the momentum wheel, and the magnetic torquer are mathematically modelled. The 3-axis attitude control logic is implemented to make the closed-loop system and simulations are carried out to verify the implemented control laws.

• 전자공학회논문지 IE
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• 제44권2호
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• pp.21-25
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• 2007

본 논문에서는 표면저항을 이용한 차폐성능 및 다층박막의 광학설계 후, roll- to-roll DC 스퍼터링 공정을 이용하여 PET(Polyethylene terephtalate) 필름위에 투명 전도성 산화물 박막인 ITO와 금속을 다층박막 구조(Multilayer)로 균질하게 증착한 전파차폐필름을 1m 넓이로 제작하고 광투과 및 전파차폐특성을 조사하였다. 각 층의 면저항 및 두께에 따라서 전자파 차폐성능과 광투과도를 최적화 할 수 있도록 설계되었고, 그 조건에 따라 필름을 제작하였다. 제작된 전파차폐필름은 2-18GHz 대역에서 99.5%의 차폐성능을 나타내었으며, 400-700 nm에서의 전광선 투과율은 83.1%로 우수한 시인성과 전파차폐특성을 보유하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.704-709
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• 2004

This paper presents the laser processing to adjust the roll and pitch directions of the flex suspension assembly for hard disk drive production. The adjustment is accomplished using a number of laser beam projections that can be approximated using the regression model of the existing measured roll and pitch directions. Information derived from the analysis can be applied to control the quality of flex suspension assembly. The performances of the proposed technique were observed using the flex suspension assembly plant in Thailand as an illustrative case study. The experimental results are given to support the improving manufacturing yields and some economic benefits of the proposed technique.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1068-1071
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• 1996

Good shape on flat rolled product is necessary to meet today's customer quality requirement. To meet the increasing demand in quality of strip shape from downstream customers, POSCO has replaced the Automatic Shape Control(ASC) system with the existing one that had used noncontact type measuring system at No.2 Cold Rolling Mill, Pohang works in October, 1995. The strip shape is influenced by the profile, roll crown, bending control, skew control system, as well as work roll cooling system. We have used ASC to adjust those factors in Cold Rolling Mill that could get a satisfactory result, almost less than .+-.5 1-unit deviation from the target shape. However, the downstream customer(i.e. Continuos Annealing Line) wants a good shape not only at the moment of exit of roll bite, but after rolling without tension. In this investigation, the difference will be discussed and how deal with this problem.