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Institution

Sungkyunkwan University

EducationSeoul, South Korea
About: Sungkyunkwan University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Graphene & Thin film. The organization has 28229 authors who have published 56428 publications receiving 1352733 citations. The organization is also known as: 성균관대학교.


Papers
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Journal ArticleDOI
TL;DR: It is proposed that this large work function shift forces the Fermi level of the SWCNTs to be located deep in the valence band, i.e., highly degenerate, creating empty van Hove singularity states, and hence the work functionshift invokes a new asymmetric transition in the absorption spectroscopy from a deeper level to newly generated empty states.
Abstract: We investigated the modulation of optical properties of single-walled carbon nanotubes (SWCNTs) by AuCl 3 doping. The van Hove singularity transitions (E 11 (S), E 22 (S), E 11 (M)) in absorption spectroscopy disappeared gradually with an increasing doping concentration and a new peak appeared at a high doping concentration. The work function was downshifted up to 0.42 eV by a strong charge transfer from the SWCNTs to AuCl 3 by a high level of p-doping. We propose that this large work function shift forces the Fermi level of the SWCNTs to be located deep in the valence band, i.e., highly degenerate, creating empty van Hove singularity states, and hence the work function shift invokes a new asymmetric transition in the absorption spectroscopy from a deeper level to newly generated empty states.

242 citations

Proceedings ArticleDOI
14 Feb 2012
TL;DR: A new file system for SSDs, SFS, which exploits the maximum write bandwidth of SSD by taking a log-structured approach and transforms all random writes at file system level to sequential ones at SSD level.
Abstract: Over the last decade we have witnessed the relentless technological improvement in flash-based solid-state drives (SSDs) and they have many advantages over hard disk drives (HDDs) as a secondary storage such as performance and power consumption. However, the random write performance in SSDs still remains as a concern. Even in modern SSDs, the disparity between random and sequential write bandwidth is more than tenfold. Moreover, random writes can shorten the limited lifespan of SSDs because they incur more NAND block erases per write.In order to overcome these problems due to random writes, in this paper, we propose a new file system for SSDs, SFS. First, SFS exploits the maximum write bandwidth of SSD by taking a log-structured approach. SFS transforms all random writes at file system level to sequential ones at SSD level. Second, SFS takes a new data grouping strategy on writing, instead of the existing data separation strategy on segment cleaning. It puts the data blocks with similar update likelihood into the same segment. This minimizes the inevitable segment cleaning overhead in any log-structured file system by allowing the segments to form a sharp bimodal distribution of segment utilization.We have implemented a prototype SFS by modifying Linux-based NILFS2 and compared it with three state-of-the-art file systems using several realistic workloads. SFS outperforms the traditional LFS by up to 2.5 times in terms of throughput. Additionally, in comparison to modern file systems such as ext4 and btrfs, it drastically reduces the block erase count inside the SSD by up to 7.5 times.

242 citations

Journal ArticleDOI
TL;DR: In this article, a self-sensing method based on the dielectric elastomer (DE) actuator/sensor was successfully developed and evaluated in order to extract accurate displacement information during the actuation process without using any additional sensing device.
Abstract: A novel self-sensing method based on the dielectric elastomer (DE) actuator/sensor, was successfully developed and evaluated in order to extract accurate displacement information during the actuation process without using any additional sensing device. The proposed self-sensing method is based on a capacitance characteristic of a DE actuator. The DE actuator with a serial external resistor can serve as an electrical high-pass filter. The voltage gained using the high-pass filter, which is virtually built by the DE, varies due to the change of overall capacitance when the DE actuator is expanded electro-mechanically. To realize actuating and sensing simultaneously with a DE actuator, we used a modulation technique to mix signals, which have a low frequency signal for actuating and a high frequency with small amplitude for sensing. Several experiments were performed to verify the usability of the proposed self-sensing method. The results showed a fine resolution and an excellent correlation with the displacements measured by a laser displacement sensor.

242 citations

Journal ArticleDOI
TL;DR: The overall recent progress made in developing MoS2 based flexible FETs, OLED displays, nonvolatile memory (NVM) devices, piezoelectric nanogenerators (PNGs), and sensors for wearable electronic and optoelectronic devices is discussed.
Abstract: Flexible, stretchable, and bendable materials, including inorganic semiconductors, organic polymers, graphene, and transition metal dichalcogenides (TMDs), are attracting great attention in such areas as wearable electronics, biomedical technologies, foldable displays, and wearable point-of-care biosensors for healthcare. Among a broad range of layered TMDs, atomically thin layered molybdenum disulfide (MoS2) has been of particular interest, due to its exceptional electronic properties, including tunable bandgap and charge carrier mobility. MoS2 atomic layers can be used as a channel or a gate dielectric for fabricating atomically thin field-effect transistors (FETs) for electronic and optoelectronic devices. This review briefly introduces the processing and spectroscopic characterization of large-area MoS2 atomically thin layers. The review summarizes the different strategies in enhancing the charge carrier mobility and switching speed of MoS2 FETs by integrating high-κ dielectrics, encapsulating layers, and other 2D van der Waals layered materials into flexible MoS2 device structures. The photoluminescence (PL) of MoS2 atomic layers has, after chemical treatment, been dramatically improved to near-unity quantum yield. Ultraflexible and wearable active-matrix organic light-emitting diode (AM-OLED) displays and wafer-scale flexible resistive random-access memory (RRAM) arrays have been assembled using flexible MoS2 transistors. The review discusses the overall recent progress made in developing MoS2 based flexible FETs, OLED displays, nonvolatile memory (NVM) devices, piezoelectric nanogenerators (PNGs), and sensors for wearable electronic and optoelectronic devices. Finally, it outlines the perspectives and tremendous opportunities offered by a large family of atomically thin-layered TMDs.

241 citations

Journal ArticleDOI
TL;DR: Cytotoxicity study showed that copolymers exhibited no cytotoxic effects on cells even at high copolymer concentration, and transfection efficiency was influenced by PEG molecular weight.

241 citations


Authors

Showing all 28506 results

NameH-indexPapersCitations
Michael Grätzel2481423303599
Hyun-Chul Kim1764076183227
Yongsun Kim1562588145619
David J. Mooney15669594172
Jongmin Lee1502257134772
Byung-Sik Hong1461557105696
Inkyu Park1441767109433
Y. Choi141163198709
Kazunori Kataoka13890870412
E. J. Corey136137784110
Pasi A. Jänne13668589488
Suyong Choi135149597053
Intae Yu134137289870
Tae Jeong Kim132142093959
Anders Hagfeldt12960079912
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023103
2022588
20214,342
20204,248
20194,124
20183,826