• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.74-80
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• 2021

When a berth is built close to a fairway, a moored vessel will be affected by the ship waves generated by navigating vessels. In this study, a portable measurement system was developed to measure the roll motion of an actual vessel, and the results were compared with simulation results. The simulation results showed that the roll motion satisfies the loading safety criteria. However, the actual results of the vessel, did not satisfy the criteria in some cases. In this study, 18 cases that did not satisfy the loading safety criteria were analyzed. Among these cases, three cases were affected by a different time zone of the remaining 15 cases, 11 cases (73.3%) were observed to be consistent with arrival times of passenger ships of more than 10,000GT sailing between in Mokpo and Jeju. The results of this study can be used to reflect marine traffic characteristics in the assessment of loading safety, which can increase the reliability of results of the loading safety assessment of ships.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.64-64
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• 2008

연속공정이 가능한 Roll to Roll sputter system을 이용하여 플렉시블 indium tin oxide(ITO) 투명전극을 PET(polyethlyene terephthalate) 기판위에 성막하였다. 연속 성막공정을 위해 Roll to Roll sputter system에서의 unwinder roller와 rewinder roller를 이용한 servomotor의 rolling으로 기판의 움직임이 완벽히 제어되었으며, 외부 응력으로 부터의 안정성 및 성막 공정 시의 PET 기판의 열적 변형을 최소화하기 위한 접촉식 냉각방식의 cooling system을 main drum으로 사용하였다. 또한 고분자 기판과 투명전극 사이의 adhesion을 향상시키기 위한 전처리 공정으로 gridless linear ion beam source를 pretreatment system으로 구축하였다. 이렇게 제작된 Roll to Roll sputter system을 이용하여 PET 기판위에 연속공정을 통해 ITO 투명전극을 성막하였다. 성막된 플렉시블 ITO/PET 투명전극은 XRD, HREM, SEM 분석을 통하여 main drum의 cooling에 의해 완전한 비정질 구조를 나타내었음을 확인할 수 있었으며, 비록 Roll to Roll sputter system을 통하여 상온에서 성막 되었음에도 불구하고 최적화 된 조건에서 가시광선 영역 83.46 %의 높은 광투과도 값과 47.4 Ohm/square의 비교적 낮은 먼저항 값을 얻을 수 있었다. 또한 Bending test 결과를 통하여 ion source의 전처리 공정으로 굽힘/평의 반복적 응력에 따른 전기적 특성 열화를 최소화 할 수 있음을 보였다. 최적화된 플렉시블 투명전극을 이용하여 P3HT:PCBM 기반의 플렉시블 유기태양전지를 제작하였으며, 제작된 유기태양전지로부터 1.88%의 power conversion efficiency (PCE)을 확보함으로써 플렉시블 유기태양전지 제작을 위한 ITO/PET 투명전극 성막 공법으로써 Roll to Roll sputter system의 적용가능성을 확인할 수 있었다.

• Journal of Biosystems Engineering
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• v.26 no.1
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• pp.47-56
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• 2001

In order to prevent the possibility of mixing of metal powder during food grinding processing with the metal roll mill this study was conducted to develope the materials of ceramics roll as a substitute of gray cast iron mill. Since the ceramics is brittle material and can be broken easily by a crack, it was needed to develope engineering ceramics roll materials with high elastic modulus and fracture toughness. Adding 0∼50 wt% Al$_2$O$_3$as densification additives to porcelain body material and forming the ceramics an different condition, mechanical properties were evaluated. The material structure’s densification process was analyzed by SEM and XRD. The evaluation of the mechanical properties of ceramics roll materials were compared and analyzed by non-destructive test using Young’s modulus and destructive test using 3-point bending strength and fracture toughness. The results showed several correlative results. Porcelain body material with 40 wt% Al$_2$O$_3$content heated at 1,200$\^{C}$ for 5h was high bulk density of 2.77, Young’s modulus of 118.4Gpa, 3-point bending strength of 137 MPa and fracture toughness of 2.88 MPa$.$m$\^$$\sfrac{1}{2}$/ . After analyzing the relationship between non-destructive test and destructive test, the coefficient of determination was more than 0.9. Therefore, the evaluation of non-destructive test by ultrasonic was turned out to be feasible in evaluating the mechanical properties of ceramics.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1255-1258
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• 2008

Roll to roll (R2R) system, known as 'web processing', is the process of producing these electronic devices on a roll of flexible plastic. With the need of improved performance and productivity in R2R industry, effective control and on-line supervision for web quality is essential. In this report, we present a system for on-line measurement of wrinkles, one of defects incurring due to compressive stresses developed in the web. This system is able to capture an image generated when a well defined line shape laser beam passes through a transparent web. The system calculates 3D shape information, including the height of the wrinkle on the web, and displays the images for the shape information of the web in real time. By using area scan camera and machine vision laser, this system takes more advantages of setting up as a simple and low cost system compared to the line scan camera systems that widely used in web manufacturing. Specific calibration method and analysis on the achievable accuracy will be discussed.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.145-154
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• 2001

A new type of modular mirror manipulator with independent adjustability was developed for the EPU6 beamline under construction at the Pohang Accelerator Laboratory. The mirror manipulator was designed so that the angular displacements of roll and pitch rotations do not introduce translational displacements and are independent with each other by positioning the mirror center to the center of a newly devised spherical joint. Manipulating its roll and pitch micrometers, the rotation angles of a dummy mirror were measured at an accuracy of 5 $\mu$rad using a gravity-referenced inclinometer. While the designed angular resolution was 3.937 $\mu$rad/$\mu\textrm{m}$, measured angular resolutions were 3.94 $\mu$rad/$\mu\textrm{m}$ for roll rotation and 3.85 $\mu$rad/$\mu\textrm{m}$ for pitch rotation. The effect of roll rotation on pitch angles was measured to be -3.18% and the effect of pitch rotation on roll angles was measured to be -5.21%. As the mirror manipulator was designed with emphases on independent adjustability and standardization, it results in eases of manufacturing, installation and adjustment as well as reductions of development period and design cost of mirror manipulators for various types of mirrors.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.573-574
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• 2013

본 연구에서는 Roll-to-Roll 스퍼터를 이용한 ITO 성막 공정에서 Ar 이온 빔 처리가 플렉시블 ITO 박막의 전기적, 광학적, 구조적 특성에 미치는 효과를 연구하였다. Roll-to-Roll 스퍼터를 이용하여 ITO 박막을 성막할 때 Linear ion source를 이용하여 Ar 이온을 ITO 박막에 직접 조사할 때 일어나는 ITO 박막의 변화를 분석하였다. Ar 이온 빔에 인가되는 DC 파워 변화에 따른 ITO 박막의 전기적, 광학적 특성 변화를 Hall measurement 및 UV/Visible spectrometry 분석법을 통해 확인하였다. 이온 빔 처리 공정 시 인가되는 파워가 DC 100 W일 때 $5.81{\times}10^{-4}{\Omega}-cm$으로 이온 빔 처리를 하지 않은 $1.14{\times}10^{-3}{\Omega}-cm$에 보다 낮은 비저항을 나타냄을 확인할 수 있었다. 이온 빔 처리 전/후 ITO 박막의 결정성은 포항 가속기 X-ray scattering법을 이용하여 분석하였으며, 결과를 통해 Ar 이온 빔 처리가 ITO 박막의 표면에서의 국부적인 결정성을 향상을 일으킴을 알 수 있었다. 이러한 결정성 향상이 Roll-to-Roll 스퍼터된 ITO 박막의 전기적 특성을 향상과 매우 밀접한 관계가 있음을 확인할 수 있었다. 또한 이온 빔 처리 전/후 ITO/CPI의 기판 휨에 따른 기계적 안정성을 알아보기 위해 bending frequency 60 Hz, bending radius 15mm로 bending test를 진행을 통하여 이온 빔 처리 전후 ITO 박막의 특성을 비교 확인하였다. 본 실험 결과를 통해 Ar 이온빔 조사에 의해 상온에서 결정형 ITO 박막을 CPI 기판위에 형성 할 수 있었다. 또한 최적화된 ITO 박막을 이용하여 유기 태양전지를 제작하였으며 이를 통해 Ar 이온빔 처리된 결정형 ITO의 유연 태양전지 응용 가능성을 타진하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.22-28
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• 2011

This paper presents an active roll motion control of a passenger vehicle. The roll controller is designed in the framework of $H_{\infty}$ control scheme based on the 3 DOF vehicle model taking into consideration parameter variations, which affect the roll dynamics, and unmodeled high frequency dynamics for robustness and performance. In order to investigate the feasibility of the active roll control system in a car, its performance is evaluated by simulation in a full vehicle model with nonlinear tire characteristics under various operating conditions. Finally, in order to enhance the performance in a transient region taking into account the limited bandwidth of the actuating module, a hybrid control strategy is presented.

• Journal of Broadcast Engineering
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• v.18 no.4
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• pp.589-598
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• 2013

In order to understand 3D visual fatigue, it is necessary to examine the visual fatigue induced by camera parameters as well as that induced by a pre-existing 3D content. In the present study, we examined the effects of camera parameters, such as roll misalignment error, shooting distance and vergence condition on 3D visual fatigue and we modelled it. The results indicate that roll misalignment error, shooting distance and vergence condition affect 3D visual fatigue and the effect of roll misalignment error on 3D visual fatigue is evident specifically when screen disparity is relatively small.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.3
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• pp.199-203
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• 2017

Hot embossing techniques are used to engrave patterns on plastic substrates. Roll based hot embossing uses a heated roll for a continuous process. A heated roll with relief patterns is impressed on a preheated plastic substrate. Then, the substrate is cooled down quickly to prevent thermal shrinkage. The roll speed is normally very slow to ensure substrate temperature increase up to the glass transition temperature. In this paper, we propose a noncontact preheating technique using focused infrared light. The infrared light is focused as a line beam on a plastic substrate using an elliptical mirror just before entering the hot embossing roll. The mid range infrared light efficiently raises the substrate temperature. For preliminary tests, substrate deformation and temperature changes were monitored according to substrate speed. The experiments show that the proposed technique is a good possibility for high speed hot embossing.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.118-125
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• 2015

The roll-forming process is a highly productive incremental forming process and is suitable for manufacturing thin, high-strength steel products. Recently, this process has been considered one of the most productive processes in manufacturing high-strength steel automotive structural parts. However, it is very difficult to develop the roll-forming process when the cross-sectional shape of the product changes in the longitudinal direction. In this study, a roll-forming process for manufacturing high-strength steel automotive parts with a linearly variable symmetric hat-type cross-section was developed. The forming rolls were designed by the 3D CAD system, CATIA. Additionally, the designed forming rolls were modified by the simulation through the 3D elastic-plastic finite element analysis software, MARC. The results of the finite element analysis show that the final roll-forming roll can successfully produce the desired high-strength steel automotive part with a variable cross-section.