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排序方式: 共有1046条查询结果,搜索用时 11 毫秒
41.
A Surface Tailoring Method of Ultrathin Polymer Gate Dielectrics for Organic Transistors: Improved Device Performance and the Thermal Stability Thereof
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Hyejeong Seong Jieung Baek Kwanyong Pak Sung Gap Im 《Advanced functional materials》2015,25(28):4462-4469
Tailoring the surface of the dielectric layer is of critical importance to form a good interface with the following channel layer for organic thin film transistors (OTFTs). Here, a simple surface treatment method is applied onto an ultrathin (<15 nm) organosilicon‐based dielectric layer via the initiated chemical vapor deposition (iCVD) to make it compatible with organic semiconductors without degrading its insulating property. A molecular‐thin oxide capping layer is formed on a 15 nm thick poly(1,3,5‐trimetyl‐1,3,5‐trivinyl cyclotrisiloxane) (pV3D3) by a brief oxygen plasma treatment. The capping layer greatly enhances the thermal stability of the dielectrics, without degrading the original mechanical flexibility and insulating performance of the dielectrics. Moreover, the surface silanol functionalities formed by the plasma treatment can also be utilized for the surface modification with silane compounds. The surface‐modified dielectrics are applied to fabricate low‐voltage operating (<5 V) pentacene‐based OTFTs. The highest field‐effect mobility of the device with the surface‐treated 15 nm thick pV3D3 is 0.59 cm2 V?1 s?1, which is improved up to two times compared to the TFT with the pristine pV3D3. It is believed that the simple surface treatment method can widely extend the applicability of the highly robust, ultrathin, and flexible pV3D3 gate dielectrics to design the surface of the dielectrics to match well various kinds of organic semiconductors. 相似文献
42.
Kwang-Hee Im In-Young Yang Sun-Kyu Kim Jong-An Jung Young-Tae Cho Yong-Deuck Woo 《Journal of Mechanical Science and Technology》2016,30(10):4413-4416
Terahertz ray (T-ray) scanning applications are promising tools. The use of T-ray for nondestructive evaluation was investigated on composite materials. In this characterization procedure, electromagnetic properties, such as the refractive index, were analyzed. The estimates of properties are in good agreement with known data. We successfully demonstrated the characteristics of T-ray propagating through Carbon fiber-reinforced plastic (CFRP) composites to acquire the refractive index by using the characterized material properties. A T-ray technique was developed for measuring paint thickness on CFRP laminates. Good results were obtained from tests performed on standard paint samples with thickness starting from approximately 100 μm. The method was based on reflection mode measurement with time of flight. Another method developed for measuring paint thickness using resonance frequencies was utilized to determine paint thickness on composite laminates. The paint thickness deduced from resonance frequencies agrees well with the result obtained directly from time-domain echoes. 相似文献
43.
Near‐infrared‐active and pH‐responsive fluorescent polymer‐integrated hybrid graphene oxide nanoparticles for the detection and treatment of cancer
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Shazid Md. Sharker Eun Bi Kang Chun‐Im Shin Sung Han Kim Gibaek Lee Sung Young Park 《应用聚合物科学杂志》2016,133(32)
Hybrid nanoparticles for theragnosis have great potentiality to bring desire functionalities in one integrated system. The development of bioimaging guided photothermal therapy (PTT) is pivotal in optimizing cytotoxic cancer therapy. We report near‐infrared (NIR)‐active and pH‐responsive fluorescent, catechol‐conjugated, reduced graphene oxide (rGO)‐anchored hybrid nanoparticles that can sharply increase the photothermal heat in response to NIR exposure and exhibit pH‐dependent fluorescence emission for the detection of tumor areas without causing cell toxicity. The optoelectronic absorption property of poly(3,4‐ethylenedioxythiophene) [PEDOT]:dopamine‐conjugated poly(4‐styrenesulfonate‐co‐maleic acid) [D‐PSM] and 3′,4′‐dihydroxyacetophenone/boron‐dipyrromethene [CCDP/BODIPY]‐quaternized polyethylene glycol grafted poly(dimethylaminoethyl methacrylate) (C/B‐PgP) present in this hybrid nanoparticles resulted in efficient photothermal conversion with pH‐tunable fluorescence that exerted sufficient photothermal cytotoxicity to cancer cells. The in vitro cellular uptake was measured by confocal laser scanning microscopy, allowing the therapeutic efficiency and bioimaging effects to be explored. We expect that the broad optical absorption property of PEDOT:D‐PSM with BODIPY‐conjugated polymers on rGO sheets would get tremendous attraction in this enormous rising PTT with cancer detectable biomarker. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43791. 相似文献
44.
Jong-Soo Kim Yong-Bim Im Ngoc-Hung Bui 《Journal of Mechanical Science and Technology》2005,19(9):1790-1800
The examination on the operating mechanism of a pulsating heat pipe (PHP) using visualization revealed that the working fluid
in the PHP oscillated to the axial direction by the contraction and expansion of vapor plugs. This contraction and expansion
is due to the formation and extinction of bubbles in the evaporating and condensing section, respectively. In this paper,
a theoretical model of PHP was presented. The theoretical model was based on the separated flow model with two liquid slugs
and three vapor plugs. The results show that the diameter, surface tension and charge ratio of working fluid have significant
effects on the performance of the PHP. The following conclusions were obtained. The periodic oscillations of liquid slugs
and vapor plugs were obtained under specified parameters. When the hydraulic diameter of the PHP was increased to d=3mm, the
frequency of oscillation decreased. By increasing the charging ratio from 40 to 60 by volume ratio, the pressure difference
between the evaporating section and condensing section increased, the amplitude of oscillation reduced, and the oscillation
frequency decreased. The working fluid with higher surface tension resulted in an increase in the amplitude and frequency
of oscillation. Also the average temperature of vapor plugs decreased. 相似文献
45.
Crude extract and solvent-partitioned fraction of Glehnia littoralis were found to possess different anti-proliferative effects against AGS, HT1080 and U937 human cancer cells. The crude extracts and solvent fractions dose-dependently inhibited cell proliferation. Especially, n-hexane and 85% aqueous MeOH fractions exhibited comparatively higher anti-proliferative effects and reduced expressions of Bcl-2, COX-2 and iNOS genes. Systematic separation of all solvent fractions by chromatographic methods led to the isolation of three glucopyranosides, four furanocoumarins and two polyacetylenic alcohols. All the nine compounds were evaluated for their inhibitory effects against both proliferation of human cancer cells and expressions of MMP-2 and -9 in HT1080 cells. Two polyacetylenic alcohols exerted the highest inhibitory activity against both human cancer cell lines, and MMP-2 and -9. These results suggest that G. littoralis may possibly be used as a valuable chemopreventive agent or food supplement for reducing cancer risk. 相似文献
46.
Ji Sun Im Seok Chang Kang Byong Chol Bai Tae-Sung Bae Se Jin In Euigyung Jeong Sei-Hyun Lee Young-Seak Lee 《Carbon》2011,(7):2235-2244
A high-performance NO gas sensor was prepared by inducing thermal fluorination of carbon nanotube semiconductors. Thermal fluorination of multi-walled carbon nanotubes (MWCNTs) was carried out at various temperatures (100 ∼ 1000 °C) to investigate the effects of the reaction temperature. The mechanism of high-performance NO gas sensor electrode was shown to depend on the fluorination temperature in a way that can be divided into three regions, separated at 400 and 1000 °C. In the first temperature region, the induction of fluorine functional groups onto MWCNTs showed the opposite trend in electrical resistance change comparing with traditional p-type MWCNTs. In the second temperature region, the induced fluorine functional groups were attenuated by generated fluorinated carbon gases resulting in the decomposition of MWCNTs and the recovery of traditional p-type gas sensor behavior. In the highest temperature region above 1000 °C, reoriented carbon structure was observed, showing bent nanotubes produced from destruction by fluorination and subsequent reorientation due to the high temperature. The gas sensing responsiveness was significantly improved by the thermal fluorination, which causes electrophilic attraction, creates adsorption sites for target NO gases and improve hydrophobicity for gas sensing stability in humid condition. In conclusion, a high-performance gas sensor was obtained by thermal-fluorination of MWCNTs. 相似文献
47.
Thin‐Film Transistors: Synthesis of Ultrathin,Homogeneous Copolymer Dielectrics to Control the Threshold Voltage of Organic Thin‐Film Transistors (Adv. Funct. Mater. 36/2016)
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Kwanyong Pak Hyejeong Seong Junhwan Choi Wan Sik Hwang Sung Gap Im 《Advanced functional materials》2016,26(36):6672-6672
48.
Im Deok Jung Min Kook Cho Kong Myeong Bae Sang Min Lee Phill Gu Jung Ho Kyung Kim Sung Sik Kim Jong Soo Ko 《ETRI Journal》2008,30(5):747-749
We introduce a pixel‐structured scintillator realized on a flexible polymeric substrate and demonstrate its feasibility as an X‐ray converter when it is coupled to photosensitive elements. The sample was prepared by filling Gd2O2S:Tb scintillation material into a square‐pore‐shape cavity array fabricated with polyethylene. For comparison, a sample with the conventional continuous geometry was also prepared. Although the pixelated geometry showed X‐ray sensitivity of about 58% compared with the conventional geometry, the resolving power was improved by about 70% above a spatial frequency of 3 mm?1. The spatial frequency at 10% of the modulation‐transfer function was about 6 mm?1. 相似文献
49.
Gun Joo Jung Sung Ki Song Young Chull Ahn Geun Sug Oh Young Bin Im 《Journal of Mechanical Science and Technology》2011,25(2):503-512
This research has investigated physical variables affecting indoor thermal comfort and subjective responses of thermal comfort
of students in a university in Korea in which the weather is oceanic temperate climate, and has been performed to contribute
to the research fields of Sustainable Thermal Standard and Adaptive Thermal Comfort (ATC). This research is based on the ISO
7730-2005 standard and the ATC theories and 4 main variables of PMV such as dry bulb temperature (Ta), relative humidity (RH),
black bulb temperature (Tg), and air velocity (Va) are measured once a week during two regular semesters. A clothing insulation,
a thermal sensation vote (TSV), an acceptability of thermal environment, and a preference for cooling and heating are investigated
at the same time using a questionnaire. This study was carried out for 26 weeks during the spring season, from March to June
2009, and the autumn season, from September to December 2009. The main achievements of this study are as follows. Monthly
Mean Outdoor Temperature (MMOT) and Operative Temperature (OT) in the classroom during research periods are 7.4∼23.3°C and
17.5∼29.0°C, respectively. The acceptability ratio of thermal environment shows over 80% when the range of OT in the classroom
is 17∼25°C, and the range can be applicable to operative index of heating and cooling of classroom. The mean TSV of respondents
is almost “neutral (0)” when the PMV in the classroom moves to “neutral (0)” and “slightly cool (−1)”, and the TSV is almost
“+1.5” when the PMV moves to “slightly warm (+1)”. The acceptability ratio of thermal environment is slightly different from
ASHRAE Standard 55-2004. So it is necessary to more investigate standard range of acceptability of thermal environment in
oceanic temperate climate region using much more databases. 相似文献
50.
Eun Kyoung Kim Jong Seok Bae Seung Soon Im Byoung Chul Kim Yang Kyoo Han 《应用聚合物科学杂志》2001,80(9):1388-1394
To obtain long branched polybutylene succinate (PBS), modified PBSs were prepared by introducing a branching agent, trimethylol propane (TMP), to the polycondensation system of succinic acid and 1,4‐butanediol. Molecular parameters such as absolute molecular weight and root‐mean‐square (RMS) radius of the modified PBSs were measured by gel permeation chromatography (GPC) with a multiangle laser light‐scattering (MALLS) detector. The RMS radius of TMP05, PBS prepared by incorporating 0.5 wt % TMP during polycondensation, was the smallest of all PBSs tested at the same molecular weight. The notable shear thinning and much reduced loss tangent for TMP05 qualitatively supported the difference in their molecular structures predicted by GPC. The analytical results indicated that introducing 0.5 wt % TMP produced PBS with chain branches long enough to produce molecular entanglements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1388–1394, 2001 相似文献