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롤투롤 시스템의 공기 부양 건조기 건조 성능 및 안정성 향상을 위한 부가물 장착 구조 성능 평가
문자훈(Jahoon Moon),응웬쯔엉신(Truong Sinh Nguyen),이택민(Taik-Min Lee),장윤석(Yunseok Jang),이승현(Seung-Hyun Lee) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
In the coating manufacturing process using R2R system, the drying process for complete drying of wetted ink is one of the most important processes in R2R system. A double-side coating which is one of coating techniques is adopted for improving productivity or meeting special purposes. In the case of double-side coating, wetted coating area should be dried without direct contact with the rolls to prevent damage to the coating area and system components. For this reason, an air floating dryer that performs drying in a non-contact support state when drying a double-side coating has been used. In this study, we proposed the modified structures with additional part of an air floating dryer to achieve more stable drying performance. In order to evaluate stabilization performances of the modified structure, the pressure characteristics of the floating drying systems were numerically investigated. From the numerical results, the considerably effective arrangement and design parameter were determined to make uniform pressure distribution. In the results of optimal case, the pressure difference between maximum and minimum pressure on the substrate is reduced about 23.6% compared to the conventional system. Furthermore, the position of starting point of the cushion effect is delayed about 8.7%.
롤투롤 시스템의 공기 부양 건조기 건조 성능 및 안정성 향상을 위한 부가물 장착 구조 성능 평가
문자훈(Jahoon Moon),응웬쯔엉신(Truong Sinh Nguyen),이택민(Taik-Min Lee),장윤석(Yunseok Jang),이승현(Seung-Hyun Lee) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
In the coating manufacturing process using R2R system, the drying process for complete drying of wetted ink is one of the most important processes in R2R system. A double-side coating which is one of coating techniques is adopted for improving productivity or meeting special purposes. In the case of double-side coating, wetted coating area should be dried without direct contact with the rolls to prevent damage to the coating area and system components. For this reason, an air floating dryer that performs drying in a non-contact support state when drying a double-side coating has been used. In this study, we proposed the modified structures with additional part of an air floating dryer to achieve more stable drying performance. In order to evaluate stabilization performances of the modified structure, the pressure characteristics of the floating drying systems were numerically investigated. From the numerical results, the considerably effective arrangement and design parameter were determined to make uniform pressure distribution. In the results of optimal case, the pressure difference between maximum and minimum pressure on the substrate is reduced about 23.6% compared to the conventional system. Furthermore, the position of starting point of the cushion effect is delayed about 8.7%.
Forced convection heat transfer from an asymmetric wavy cylinder at a subcritical Reynolds number
Moon, Jahoon,Yoon, Hyun Sik,Kim, Hyo Ju,Kim, Min Il Elsevier 2019 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.129 No.-
<P><B>Abstract</B></P> <P>The present study considered the asymmetric wavy (ASW) disturbance which has been confirmed as the passive control to modify the force coefficients Yoon et al. [25]. We evaluated the effect of the asymmetric wavy disturbance on the forced convection heat transfer. For the purpose of the comparison, the smooth (CY) and symmetric wavy (SW) cylinders are considered. Finally, the LES has been carried out to solve the momentum and energy equations governing the flow and thermal fields at the subcritical Reynolds number of 3000. The validation of the present numerical methods were successively done by comparing the force coefficients and the Nusselt number with the previous results. The ASW cylinder provided the smallest mean and fluctuation of the time-and total surface-averaged Nusselt number than the CY and SW cylinders. This dependence of the Nusselt number on the cylinder shape is correlated to the force coefficients. The time-and local spanwise surface averaged Nusselt number of the SW cylinder shows the regional dependent behaviors of an invariant region and an increasing region. The ASW cylinder shows the increasing and decreasing behaviors in the short and long wavelength parts. The double wavy formation of the temperature isosurface in the wake for the ASW cylinder is consistent with the 3D vortical structures. The most significant variation of the time-averaged local Nusselt Number appears in the upstream surface of the SW and ASW cylinders which induce the spanwise dependent incoming flow.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effect of an asymmetric wavy disturbance on the heat transfer is originally investigated. </LI> <LI> The temperature has a double wavy formation in the wake. </LI> <LI> The Nu distribution on the surface forms the invariant and increasing zones. </LI> <LI> The ASW cylinder attenuates the heat transfer in comparison with the circular cylinder. </LI> </UL> </P>
Jin, Jahoon,Jin, Xuefan,Jung, Jaehong,Kwon, Kiwon,Kim, Jintae,Chun, Jung-Hoon IEEE 2018 IEEE journal of solid-state circuits Vol.53 No.10
<P>This paper proposes a 750-Mb/s to 3.0-Gb/s dual-mode (full and half rate) referenceless clock and data recovery (CDR) circuit in a 65-nm CMOS process. The dual-mode deadzone-compensated frequency detector (DC-FD) and the digital calibration of both bank and control voltage of voltage-controlled oscillators (VCOs) allow precise frequency acquisition even with high input jitter. The dual-mode scheme extends supported data rates, and the temperature compensation technique allows uninterrupted video transmission with a bit error rate (BER) below 10<SUP>−12</SUP> over a wide temperature range from −20 °C to 120 °C.</P>