• 반도체디스플레이기술학회지
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• 제18권4호
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• pp.120-123
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• 2019

The effect of surface plasmon on ZTO thin films was investigated. The phenomenon of depletion occurring in the interface of the ZTO thin film created a potential barrier and the dielectric layer of the depletion formed a non-mass particle called plasmon. ZTO thin film represents n-type semiconductor features, and surface current by plasma has been able to obtain the effect of improving electrical efficiency as a result of high current at positive voltage and low current at negative voltage. It can be seen that the reduction of electric charge due to recombination of electronic hole pairs by heat treatment of compound semiconductors induces higher surface current in semiconductor devices.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.67.1-67.1
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• 2012

Graphene has attracted much attention for future nanoelectronics due to its superior electrical properties. Owing to its extremely high carrier mobility and controllable carrier density, graphene is a promising material for practical applications, particularly as a channel layer of high-speed FET. Furthermore, the planar form of graphene is compatible with the conventional top-down CMOS fabrication processes and large-scale synthesis by chemical vapor deposition (CVD) process is also feasible. Despite these promising characteristics of graphene, much work must still be done in order to successfully develop graphene FET. One of the key issues is the process technique for gate dielectric formation because the channel mobility of graphene FET is drastically affected by the gate dielectric interface quality. Formation of high quality gate dielectric on graphene is still a challenging. Dirac voltage, the charge neutral point of the device, also strongly depends on gate dielectrics. Another performance killer in graphene FET is source/drain contact resistance, as the contact resistant between metal and graphene S/D is usually one order of magnitude higher than that between metal and silicon S/D. In this presentation, the key issues on graphene-based FET, including organic-inorganic hybrid gate dielectric formation, controlling of Dirac voltage, reduction of source/drain contact resistance, device structure optimization, graphene gate electrode for improvement of gate dielectric reliability, and CVD graphene transfer process issues are addressed.

• 열처리공학회지
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• 제13권5호
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• pp.355-359
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• 2000

Ion beam assisted deposition system was used to deposit CNx coatings with various thickness on the substrates of high-frequency induction hardened steels. Rolling contact fatigue tests were performed using Polymet RCF-1 machine with a constant supply of lubricant. Rolling contact fatigue life was substantially different in the steels with various thickness of CNx coatings. The optimum thickness of CNx coating was found to be $8.9{\mu}m$, showing the longest fatigue life, mainly caused by higher resistance to initiation of cracks and protective overcoat remaining to the surface failure during rolling contact fatigue. Cracks were initiated in the substrates under the surface of wear track and propagated to the surface, which eventually resulted in the failure. The reduction of fatigue life observed in the specimen with elimination of CNx coating during rolling contact fatigue was explained by the substrates deformation.

• 상하수도학회지
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• 제33권2호
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• pp.111-119
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• 2019

Electro-coagulation process has been gained an attention recently because it could overcome the membrane fouling problems in MBR(Membrane bio-reactor). Effect of the key operational parameters in electro-coagulation, current density(${\rho}_i$) and contact time(t) on membrane fouling reduction was investigated in this study. A kinetic model for ${\rho}_i$ and t required to reduce the membrane fouling was suggested under different MLSS(mixed liquor suspended solids) concentration. Total 48 batch type experiments of electro-coagulations under different sets of current densities(2.5, 6, 12 and $24A/m^2$), contact times(0, 2, 6 and 12 hr) and MLSS concentration(4500, 6500 and 8500mg/L) were carried out. After each electro-coagulation under different conditions, a series of membrane filtration was performed to get information on how much of membrane fouling was reduced. The membrane fouling decreased as the ${\rho}_i$ and t increased but as MLSS decreased. Total fouling resistances, Rt (=Rc+Rf) were calculated and compared to those of the controls (Ro), which were obtained from the experiments without electro-coagulation. A kinetic approach for the fouling reduction rate (Rt/Ro) was carried out and three equations under different MLSS concentration were suggested: i) ${\rho}_i^{0.39}t=3.5$ (MLSS=4500 mg/L), ii) ${\rho}_i^{0.46}t=7.0$ (MLSS=6500 mg/L), iii) ${\rho}_i^{0.74}t=10.5$ (MLSS=8500 mg/L). These equations state that the product of ${\rho}_i$ and t needed to reduce the fouling in certain amounts (in this study, 10% of fouling reduction) is always constant.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.95.1-95.1
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• 2011

In this work, graphene was prepared by modified Hummers method and prepared graphene was applied to electrode materials for supercapacitor. In addition, to enhance the electrochemical performance of graphene, carbon black was deposited onto graphene via chemical reduction. The effect of the carbon black content incorporated on the electrochemical properties of the graphene-based electrodes was investigated. It was found that nano-scaled carbon black aggregates were deposited and dispersed onto the graphene by the chemical reduction of acid treated carbon black and graphite oxide. From the cyclic voltammograms, carbon black-deposited graphene (CB-GR) showed improved electrochemical performance, i.e., current density, quicker response, and better specific capacitance than that of pristine graphene. This indicates that the carbon black deposited onto graphene served as an conductive materials between graphene layers, leading to reducing the contact resistance of graphene and resulted in the increase of the charge transfer between graphene layers by bridge effect.

• Tribology and Lubricants
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• 제35권4호
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• pp.237-243
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• 2019

Through this study, we investigate the effects of ultrasonic nanocrystal surface modification (UNSM) technology on the fatigue life of needle roller bearings. The fatigue life of untreated and UNSM-treated needle roller bearings is evaluated using a roller fatigue tester at various contact stress levels under oil-lubricated conditions. We can ascertain that the fatigue life of an UNSM-treated needle roller bearing was extended by approximately 34.3% in comparison with an untreated one, where the effectiveness of UNSM technology diminishes with increasing contact stress. The surface roughness and surface hardness of needle roller bearings before and after being treated by UNSM technology are compared and discussed to understand the role of UNSM technology in improving the fatigue life of needle roller bearings. In addition, a fractograph of the damaged bearings is observed using a scanning electron microscopy to shed light on the fracture mechanisms of bearings under different contact stress levels. We can therefore conclude that the application of UNSM technology to the needle roller bearings improves the fatigue life by reducing the friction coefficient and increasing the wear resistance; this may be attributed to a reduction in surface roughness from 0.5 to $0.149{\mu}m$ and an increase in surface hardness from 58 to 62 HRc.

• 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.

• 에너지공학
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• 제8권2호
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• pp.272-278
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• 1999

본 연구에서는 지름 30mm, 길이 45mm인 brass와 aluminium 원통 실린더의 접촉면이 ⅰ) 진공 상태에 있을 때 , ⅱ) silicone grease를 충전하였을 때 , ⅲ) silicone grease와 aluminium 분말 (#325) 혼합물을 충전하였을 때의 열접촉저항을 측정하였고, 그 결과를 Fouche 의 해석 모델과 비교하였다. 진공상태에서 비접촉면의 열접촉저항은 표면의 가공 상태에 따라 (2~100)$\times$$10^{-5}$($m^2$$^{\circ}C$/W)의 분포를 나타내었고 접촉 표면을 연마하였을 때에는 거친 표면에 비하여 약 30~50%의 열접촉저항저감을 나타내었다. 그러나, silicone grease를 충전했을 때에는 열접촉저항 값이 약 5~10정도 감소하는 경향을 나타내었다. Fouche 모델을 이용한 해석 결과는 silicone grease로 충전한 접촉면에 대해서 각 10~30%범위에서 아주 잘 일치하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1014-1017
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• 2006

Admittance Spectroscopic analysis was applied to study the effect of LiF buffer layer and to model the equivalent circuit for $ITO/Alq_3/LiF/Al$ device structure. The admittance spectroscopic analysis of the devices with LiF layer shows reduction in contact resistance $(R_C)$, parallel resistance $(R_P)$ and increment in parallel capacitance $(C_P)$.

• 한국전기전자재료학회논문지
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• 제16권1호
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• pp.1-4
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• 2003

The SiH$_4$soak step is widely used to prevent the WF$_{6}$ attack to the underlayer metal using the chemical vapor deposition (CVD) method. Reduction or skipping of the SiH$_4$soak process time if lead to optimizing W-plug deposition process on via. The electrical characteristics including via resistance and the structure of W-film are affected by the time of SiH$_4$soak process. The possibility of elimination of SiH$_4$soak process is confirmed In the case of W- film grown on the stable Ti/TiN underlayer.