• Transactions on Electrical and Electronic Materials
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• 제17권3호
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• pp.129-133
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• 2016

Theoretical and graphical analysis of pull-in-voltage and figure of merit for a fixed-fixed capacitive Micro Electromechanical Systems (MEMS) switch is presented in this paper. MEMS switch consists of a thin electrode called bridge suspended over a central line and both ends of the bridge are fixed at the ground planes of a coplanar waveguide (CPW) structure. A thin layer of dielectric material is deposited between the bridge and centre conductor to avoid stiction and provide low impedance path between the electrodes. When an actuation voltage is applied between the electrodes, the metal bridge acquires pull in effect as it crosses one third of distance between them. In this study, we describe behavior of pull-in voltage and figure of merit (or capacitance ratio) of capacitive MEMS switch for five different dielectric materials. The effects of dielectric thicknesses are also considered to calculate the values of pull-in-voltage and capacitance ratio. This work shows that a reduced pull-in-voltage with increase in capacitance ratio can be achieved by using dielectric material of high dielectric constant above the central line of CPW.

• Journal of Welding and Joining
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• 제31권3호
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• pp.39-43
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• 2013

It is difficult to feed welding wire stably, when the distance between welding wire feeder and welding torch is far enough. In order to solve this problem, arranging a extension wire feeder between them could be one of useful methods. However, the welding wire could be twisted up in the extension cable between extension and terminal wire feeders in the case that RPM of extension wire feeding motor is higher than that of terminal motor. In this study, feeding problem of normal push-pull wire feeding system occurred at low welding current range less than 250A. In order to solve the problem, two new wire feeding systems of push-pull type were introduced. Welding wire feeding tests were preformed in the range of 150A to 400A with the developed push-pull feeding system. In addition, weldability test was performed at the welding current of 200A, 300A, and 400A. The welding wire twisting problem that was observed in the normal feeding system did not occur in the new push-pull wire feeding system.

• 한국정보통신학회논문지
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• 제6권4호
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• pp.559-566
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• 2002

본 논문에서는 기존 WWW의 Pull 기술뿐만 아니가 Push 기술을 사용한 개별학습을 위한 WBI를 제안한다. 제안 방안은 기존 WWW 기반 원격강의를 이용한 개별화 학습의 단점을 보완하고, 보다 편리한 사용자 위주의 인터페이스를 구현하기 위하여 Pull 방식과 병행하여 Push 방식을 도입한 새로운 수업모형으로 Java 기술의 JSP와 JDBC를 사용하여 구현하였다.

• 한국군사과학기술학회지
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• 제23권3호
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• pp.221-228
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• 2020

This paper presents the radar counter jamming algorithm and ground far-field test results for the pull-off deceptive jamming signals like RGPO(Range Gate Pull Off) and VGPO(Velocity Gate Pull Off). We designed the radar counter jamming algorithm according to the characteristics of the deceptive jamming signals. This algorithm is validated by simulation before ground far-field test. The existing X-band AESA radar demonstrator was used to test the proposed algorithm. The proposed algorithm was applied to the radar processor software. The deceptive jamming signals generated using the commercial jamming signal generator. We performed the repeated ground far-field test with the test scenario. Test results show that the proposed counter deceptive jamming algorithm works in the real radar system.

• International Journal of Advanced Culture Technology
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• 제3권2호
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• pp.34-41
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• 2015

Bonding strength of a thermal sprayed coating is difficult to measure using a conventional pull-off test method. Scratch test is a potential alternative testing method. An adhesive and a cohesive bond strength of the coating can be measured by the pull-off test while the scratch test performed on the cross-section of the thermal sprayed coating can only demonstrate the cohesive bond strength of the coating. Nevertheless, it is still beneficial to perform the scratch testing on the cross-section of the coating for the sake of comparison thus providing an alternative to the pull-off test. The scratch test method can reduce testing time and cost in the long run due to a significant cost reduction in consumables and energy and time saving from the curing step of the glue used in the pull-off test. This research investigates the possibility of using the scratch test to measure the cohesive bond strength of Mo/NiCrBSi composite coating. The results from the pull-off test and the scratch test indicate that the cohesive bond strengths of the Mo composite coating show similar trend and that the cohesive bond strength are increased when increasing NiCrBSi content.

• Macromolecular Research
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• 제13권3호
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• pp.257-264
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• 2005

Polyurethanes containing z-Iysine segments in the main chain (PULL) were synthesized from 4,4'-diphe-nylmethyl diisocyanate, poly(tetramethylene glycol), and z-Iysine oligomer as a chain extender. The PULL film was treated first with a $10\%$ HBr-acetic acid solution and subsequently with a saturated sodium bicarbonate aqueous solution to produce a primary amine group on the surface (PULL-N). Lactobionic acid (LA)-immobilized PULL (PULL-L) was prepared by the coupling reaction of the PULL surface amine groups and the LA carboxylic acid groups. The surface-modified PULLs were then characterized by attenuated total reflection-Fourier transform infra-red spectroscopy, electron spectroscopy for chemical analysis, atomic force microscopy, and contact angle goniometry. In the hepatocytes adhesion experiment, the cells poorly adhered to the PULL surface, although they adhered moderately well to the PULL-N surface. On the other hand, the cells adhered well to the PULL-L surface, suggesting the good affinity of the surface $\beta$-galactose moieties for hepatocytes. When hepatocytes were cultured in the presence of epidermal growth factor for 48 h, the cells rapidly aggregated on the PULL-L surface, whereas they aggregated only slowly on the other surfaces. The PULL prepared in this study has the potential to be used as a coating material for the enhancement of hepatocyte adhesion.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.137-144
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• 2005

Recently a pressurized grouting soil nail is demanded due to problems beyond of economical and engineering purpose. In this study, a newly modified soil nailing technology named as the PGSN (Pressurized Grouting Soil Nailing) system is respected to reduced displacements of nails and increase of global slope stability. And effects of various factors related to the design of the PGSN system, such as the length of the soil nail, injected pressure and W/C ratio of cement grout in the pressurized grouting soil nail are examined throughout a series of the displacement-controlled field pull-out tests. Displacement-controlled field pull-out tests are performed in the present study and the volume of grouting are also evaluated based on the measurements. In addition, both short-term and long-term characteristics of pull-out deformations of the newly proposed PGSN system are analyzed and compared with those of the general soil nailing system by carrying out the stress-controlled field pull-out tests. From the pull-out characteristics of pressurized grouting soil nails, it is found that the effect of the length of the soil nail, injected pressure and W/C ratio of cement grout are important parameters.

• Geomechanics and Engineering
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• 제36권1호
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• pp.71-81
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• 2024

This study analyzes the pull-out behavior of tunnel-type anchorage under various joint conditions, including joint direction, spacing, and position, using a finite element analysis. The validity of the numerical model was evaluated by comparing the results with a small-scaled model test, and the results of the numerical analysis and the small-scaled model test agree very well. The parametric study evaluated the quantitative effects of each influencing factor, such as joint direction, spacing, and position, on the behavior of tunnel-type anchorage using pull-out resistance-displacement curves. The study found that joint direction had a significant effect on the behavior of tunnel-type anchorage, and the pull-out resistance decreased as the displacement level increased from 0.002L to 0.006L (L: anchorage length). It was confirmed that the reduction in pull-out resistance increased as the number of joints in contact with the anchorage body increased and the spacing between the joints decreased. The pull-out behavior of tunnel-type anchorage was thus shown to be significantly influenced by the position and spacing of the rock joints. In addition, it is found that the number of joints through which the anchorage passes, the wider the area where the plastic point occurs, which leads to a decrease in the resistance of the anchorage.

• 한국연안방재학회지
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• 제4권3호
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• pp.111-118
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• 2017

In this study, pull box members were designed by finite element analysis of a steel plate covering a pull box to secure its safety on the landing pier dedicated to the large research survey ship. It was assumed that the maximum load is due to the 250 tonf class crane used for unloading work when the working environment in the upper part of the landing pier was considered. The safety of the pull box was evaluated by the comparison between the yield strength of the steel plate and the result of stress analysis on the steel plate due to the crane load. It was found that the stress at the plate from the crane load exceeded the yield strength of the steel(205MPa) when the upper part of the pull box was protected by a $1950{\times}1950mm$ steel plate cover. In order to compensate for this, a concrete filled steel tube(CFT) column with a diameter of 150 mm and a steel thickness of 10 mm was reinforced at the center of the plate, and the finite element analysis was carried out. However, the maximum stress at the steel plate was higher than the yield strength of the steel in some load cases so that it was tried to find appropriate thickness of the steel plate and diameter of the CFT columns. Finally, the analysis results showed that the safety of the pull box was secured when the thickness of the steel plate and the diameter of the CFT column were increased to 30mm and 180mm, respectively.

• Corrosion Science and Technology
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• 제13권5호
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• pp.186-194
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• 2014

Establishment of adhesion strength measurement procedure for marine epoxy coatings was conducted in order to ensure reliability of the test results. It was found that (1) the increase in thickness of the substrates would induce increase of pull-off strength. Especially, the increase in adhesion strength with the substrate thickness increment was attributed to the transition of stress mode to the pure tensile mode excluding bending effect. (2) The longer curing time, the higher pull-off strength. It may be due to higher cross-linking density of the coating (3) The pull-off strength increases as coating thickness increases due to the diminishment of bending effect (4) The longer drying time after water immersion, the higher pull-off strength. It may be due to the evaporation of water molecule at the coating-substrate interface.