• 한국생산제조학회지
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• 제26권4호
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• pp.351-356
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• 2017

The resistance of printed patterns for electrodes fabricated using printing technology should be minimized. This parameter depends on the pattern width and thickness; however, from the viewpoint of printability, the printed patterns should be printed at the designed width. The resistance of the printed patterns as well as printability is affected by various printing conditions. In this paper, the printing condition is optimized to minimize the resistance of electrodes printed by the roll-to-roll gravure method. This is done by considering the spread ratio of pattern width as a parameter of printability using design experiments. The drying temperature, dryer fan speed, and printing speed are selected as effective factors for the experiment objective. The optimized conditions are obtained and reproducibility test using these demonstrates that the optimized conditions can produce low-resistance electrodes for printability of the pattern width.

• 한국강구조학회 논문집
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• 제27권5호
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• pp.455-470
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• 2015

본 연구에서는 국내에서 생산되어 사용되고 있는 원형 파형강판을 대상으로 전단 및 휨 강도를 보다 정확하게 산정하기 위한 방안을 제시하고자 하였다. 국내 설계기준 및 기존 연구에 대한 비교 분석을 통하여 기존식에 대한 한계를 분석하고, 실험 및 비선형 해석을 통하여 원형 파형강판에 대한 좌굴강도 설계식을 제안하였다. 본 연구에서 제안한 전단좌굴 감소계수와 한계 판폭두께비를 이용하여 실험 및 해석결과와 비교한 결과, 상당히 유사한 거동을 나타내었다. 본 연구의 결과는 원형 파형강판의 부재 설계 및 구조성능평가에 편리하게 적용될 수 있을 것으로 판단된다.

• Steel and Composite Structures
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• 제7권2호
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• pp.135-160
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• 2007

Recently, CFT column has been well-studied and reported on, because a CFT column has certain superior structural properties as well as good productivity, execution efficiency, and improved rigidity over existing columns. However, CFT column still has problems clearing the capacity evaluation between its steel tube member and high-strength concrete materials. Also, research on concrete has examined numerical values for high-strength concrete filled steel square tube columns (HCFT) to explain transformation performance (M-${\phi}$) when a short-column receives equal flexure-moment from axial stress. Moment-curvature formulas are proposed for HCFT columns based on analytic assumption described in this paper. This study investigated structural properties (capacity, curvature), through a series of experiments for HCFT with key parameters, such as strength of concrete mixed design (58.8 MPa), width-thickness ratio (D/t), buckling length to sectional width ratio (Lk/D) and concrete types (Zeolite, Fly-ash, Silica-fume) under eccentric loads. A comparative analysis executed for the AISC-LRFD, AIJ and Takanori Sato, etc. Design formulas to estimate the axial load (N)-moment (M)-curvature (${\phi}$) are proposed for HCFT columns based on tests results described in this paper.

• 한국전기전자재료학회논문지
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• 제13권11호
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• pp.932-937
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• 2000

The length extensional vibration mode of a piezoelectric ceramic substrate is used in fabricating the ultra-small size resonators and filters. In general, the three side ratios of the rectangular substrate affect the resonant characteristics of the resonator using its length extensional vibration. In this paper, their relationships are studied. We know that changing the ratio of its length to its width makes possible to change the resonant frequency of the width vibration without degrading the length extensional vibration. And frequency constant for length extensional vibration becomes slightly small as the substrate thickness becomes thin, but it does not change as its length changes. Electro-mechanical coupling factor for length extensional vibration, k$\_$31/ does not change as its length changes within length/width$\geq$4, but it becomes small as its width increases.

• 복합신소재구조학회 논문집
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• 제6권2호
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• pp.23-31
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• 2015

CFST columns are structurally superior because the concrete inside the steel tubes prevents local buckling at the tubes and the tubes confine the concrete. And, the thickness of steel tube in CFST column has been thinner with development of high-strengh steel. The thinner the steel tube of a square CFST column is, the more local buckling is likely to occur. For this reason, we developed welded built-up square steel tube with stiffeners which are placed at the center of the tube width acts as an anchor. In this study, we conduct experimental test for three specimens of the 4m long span welded built-up square CFT column with parameters of L/D and D/t. And, the test results were compared with the analysis results by M-${\phi}$-P Program.

• Transactions on Electrical and Electronic Materials
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• 제11권6호
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• pp.253-256
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• 2010

Different active layer thicknesses for zinc oxide (ZnO) bottom-contact thin-film transistors (TFTs) were fabricated with a poly-4-vinyphenol polymeric dielectric using injector type atomic layer deposition. The properties of the ZnO TFTs were influenced by the active thickness and width-to-length (W/L) ratio of the device. The threshold voltage of ZnO TFTs shifted positively as the active layer thickness decreased, while the subthreshold slope decreased. The W/L ratio of ZnO TFTs also affected the mobility and subthreshold slope. An optimized TFT structure exhibited an on-tooff current ratio of above 106 with solid saturation.

• Steel and Composite Structures
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• 제36권5호
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• pp.507-519
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• 2020

Double skin composite walls are increasingly popular and have been applied to many safety-related facilities. They come from the concept of composite slabs. Conventional connectors such as shear studs and binding bars were used in previous studies to act as the internal mechanical connectors to lock the external steel faceplates to the concrete core. However, the restraint effects of these connectors were sometimes not strong enough. In this research, a recently proposed unique type of steel truss was employed along the wall height to enhance the composite action between the two materials. Concrete-filled tube columns were used as the boundary elements. Due to the existence of boundary columns, the restraints of steel faceplates to the concrete differ significantly for the walls with different widths. Therefore, there is a need to explore the effect of height-to-width ratio on the structural behavior of the wall. In the test program, three specimens were designed with the height of 3000 mm, the thickness of 150 mm, and different widths, to simulate the real walls in practice. Axial compression was applied by two actuators on the tested walls. The axial behavior of the walls was evaluated based on the analysis of test results. The influences of height-to-width ratio on structural performance were evaluated. Finally, discussion was made on code-based design.

• Journal of Electrical Engineering and Technology
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• 제7권4호
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• pp.576-581
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• 2012

A 23 W continuous wavelength $CO_2$ laser system exited by a high-frequency LCC resonant converter is adapted to cut a biodegradable rope fabricated with polybutylene succinate. As the biodegradable rope consists of three twisted strands, the thickness changes relative to the position of the laser beam and we thus propose a method to determine exact cutting depth. In order to obtain the parameters related to the rope cutting, the experimental and theoretical cutting depths are compared and analyzed for a range of laser heat sources. The melted thickness and groove width of the cut biodegradable rope are also examined. The proposed theoretical cutting depth depends on the incident power and target velocity ratio. From these experimental results, the biodegradable rope with a diameter of 22 mm can be cut with a heat source of 50 J/cm resulting in a melted thickness of 1.96 mm and a groove width of 0.65 mm. The laser system is shown to be perfect tool for the processing of biodegradable rope without the occurrence of raveling.

• Journal of the Korean Wood Science and Technology
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• 제37권4호
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• pp.293-299
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• 2009

섬유판을 이용한 탄화보드의 제조에 있어 무할렬 탄화법 및 탄화온도에 따른 수축률, 중량감소율 및 밀도변화에 대해 검토하였다. 섬유판을 두께별(3, 4.5, 6, 18 mm)로 준비한 후, 실험실용 탄화로를 사용하여 $400^{\circ}C{\sim}1,000^{\circ}C$의 온도조건에서 탄화보드를 제조하였다. 무할렬 탄화법은 시험편에 상하 눌림판을 설치하여 압체 탄화하는 방법을 적용하였다. 압체 탄화법에 의해 섬유판의 갈라짐과 뒤틀림 현상이 발생하지 않는 무할렬 탄화보드의 제조가 가능하였다. 탄화보드의 수축률은 길이방향 10~25%, 폭방향 12~25%, 두께방향 28~48%로 두께방향이 가장 크고 탄화온도가 상승함에 따라 커지는 경향이 나타났다. 탄화보드의 중량감소율은 섬유판의 두께에 따른 큰 차이는 나타나지 않았고 탄화온도가 상승함에 따라 커지는 경향이 나타났다. 탄화보드의 밀도는 두께 3 mm의 경질 섬유판에서 가장 컸고 탄화온도가 상승함에 따라 커지는 경향이 나타났다.

• Advances in aircraft and spacecraft science
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• 제5권1호
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• pp.21-49
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• 2018

In this paper, geometric nonlinear bending characteristics of single wall carbon nanotube reinforced composite (SWCNTRC) doubly curved shell panels subjected to uniform transversely loadings are investigated. The nonlinear mathematical model is developed for doubly curved SWCNTRC shell panel on the basis of higher-order shear deformation theory and Green- Lagrange nonlinearity. All nonlinear higher order terms are included in the mathematical model. The effective material properties of SWCNTRC are estimated by using Eshelby-Mori-Tanaka micromechanical approach. The governing equation of the shell panel is obtained using the total potential energy principle and a Newton-Raphson iterative method is employed to compute the nonlinear displacement and stresses. The present results are compared with published literature. The effect of SWCNT volume fraction, width-to-thickness ratio, radius-to-width ratio (R/a), boundary condition, linear and nonlinear deflection, stresses and different types of shell geometry on nonlinear bending response is investigated.