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Effect of Tension on Conductivity of Gravure Printed Ag Layer in Roll-to-Roll Process
강현규,이창우 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
A curing process as a post-treatment of roll-to-roll (R2R) printing is designed to form a functionality of printed pattern such asconductivity when devices e.g., radio frequency identification, fuel cell, display, and flexible printed circuits board are fabricated bysolution-based printing process. Polyethylene naphthalate (PEN) as well as polyethylene terephthalate (PET), which were employedas a flexible substrate, would be stretched much in the post-treatment process due to reduced elastic modulus in high temperature. The elongation of substrate generates cracks inside the printed layer. The formation of crack triggers increasing in electricalresistance and deteriorating in the performance of the device. Therefore, the elongation of substrate should be minimized consideringthe variations of conductivity of printed layer during the R2R process. In this study, a mathematical model for the relationship amongthe operating tension, the temperature, and the conductivity of printed layer was developed. The deterioration of conductivity wasinvestigated by observation of cracks in printed layer. The conductivity of printed layer on the stretched substrate was estimated bythe proposed model. Also, operating tension was determined for guarantying conductivity even in various temperatures for posttreatmentprocess.
강현규 대한기계학회 2009 기계저널 Vol.49 No.8
롤투롤(Roll-to-roll) 기술을 이용한 전자 소자의 대량 인쇄기법이 많은 주목을 받으며 활발한 관련 연구가 이뤄지고 있다. 하지만 전자소자 인쇄를 위해서는 기존의 전통적 그래픽 인쇄에서 사용되던 인쇄기술의 도약이 필요하다. 그 중 대표적인 레지스터 제어기술을 통해 다층 구조로 이루어지는 인쇄형 전자소자의 인쇄공정간의 초정밀 위치제어 기술에 대하여 소개한다.
On the Angular Momentum Loss of Tropical Cyclones: An f-Plane Approximation
강현규,정형빈,김원호 한국기상학회 2018 Asia-Pacific Journal of Atmospheric Sciences Vol.54 No.1
The angular momentum for ideal axisymmetric tropical cyclones on the f-plane is investigated with a focus on the totalvolume integrated quantity. Budget analysis of the momentum equation at cylindrical coordinates shows that a tropical cyclone loses angular momentum during its development and mature stages due to the dynamical difference between the viscous inward-flow near the surface and the angular momentum conserving outwardflow aloft. The total relative angular momentum of a tropical cyclone, as a result, can be negative (i.e., implying anticyclonic rotation as a whole) despite intense cyclonic wind in the tropospheric layers. This anticyclonic rotation was measured in terms of the super-rotation ratio, the ratio of total relative angular momentum to the planetary angular momentum. Simulations with the numerical model of Weather Research and Forecasting (WRF) version 3.4.1 was found to be in favor of the theoretical angular-momentum budget analysis. It was revealed in the numerical simulations that the super-rotation ratio was negative, indicating a sub-rotation, as was predicted by analysis. The sub-rotation ratio was found to be less than one percent for typical tropical cyclones. To show the angular momentum decrease even in the decaying stage, numerical simulations where the thermal forcing by sea surface temperature switched off in the mature stage were carried out. In support of the angular momentum budget analysis, the results indicated that the angular momentum also decreases for a while soon after the forcing was eliminated.