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Development of Omnidirectionally Stretchable and Transparent Graphene Electrodes
Stretchable and transparent electrodes have been developed for applications in flexible and wearable electronics. For customer-oriented practical applications, the electrical and optical properties of stretchable electrodes should be independent of the directions of the applied stress, and such electrodes are called omnidirectionally stretchable electrodes. Prof. Ho Seok PARK reported a simple and cost-effective approach for the fabrication of omnidirectionally stretchable and transparent graphene electrodes with mechanical durability and performance reliability. The use of a Fresnel lens-patterned electrode allows multilayered graphene sheets to achieve a concentric circular wavy structure, which is capable of sustaining tensile strains in all directions. The as-prepared electrodes exhibit high optical transparency, low sheet resistance, and reliable electrical performances under various deformation conditions. Furthermore, computer simulations have also been carried out to investigate the response of a Fresnel lens-patterned structure on the application of mechanical stresses. This study can be significant to a large variety of potential applications, ranging from stretchable devices to electronic components in various wearable integrated systems. The research was conducted with the support of CAP business and published in one of the most world renowned research papers ACS Nano.
- No. 29
- 2018-07-05
- 3594
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Discovery of new magnetic electride materials
Electro-Active Energy Material Lab. of the Department of Energy Science studies various materials related to energy conversion, magnetism, catalyst and electronics. They are targeting the first discovery and global-top performance in electrides as new electro-active materials and focusing on the development of record-high performance thermoelectric energy conversion materials. Also, they are studying low-dimensional transition metal dichalcogenides from fundamentals to applied researches. Followings are the main research topics: 1. Electrides: Electrides are ionic compounds in which electrons act as anions occupying interstitial real space of crystal structures, not orbitals. Because the electrides show a low work function and high electron concentration, the materials are of interest for electronics and catalysts. The research team designs and synthesizes new electrides by theoretical and experimental researches for industrial applications. 2. Thermoelectric materials: Thermoelectric materials can convert electricity to heat and vice versa. Utilizing the Seebeck and Peltier effect, thermoelectric refrigeration and power generation are possible to enable efficient energy consumption. The team is developing a world-record high performance in state-of-the-art materials by studying fundamental material physics and material process. 3. Low-dimensional materials: The low-dimensional transition metal dichalcogenides utilizing a high quality single crystal and epitaxial thin film are fabricated in their laboratory. Beyond graphene, the research team explores a new two-dimensional crystal structure distinct from conventional layered structures.
- No. 28
- 2018-07-05
- 3313
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Development of a copper-catalyzed method for the synthesis of highly enantioenriched alkylboron compounds
As organoboranes are valuable reagents in organic synthesis due to their versatility in functionalization, the demand for stereochemically well-defined organoboronates is increasing. In general, the creation of simple secondary alkylboron compounds with high enantiocontrol presents a greater challenge than the production of boron compounds with a biasing or directing substituent. Recent approaches to the synthesis of organoboron compounds by copper-catalyzed allylic substitution is the installation of the C?B bond using a diboron or 1,1-diborylalkanes as the organometallic component. All of these methods discard one B moiety from the diboron starting materials during activation and require the use of stereochemically well-defined prochiral allylic electrophiles. Herein, Prof. YUN reports a highly enantioselective synthesis of homoallylic alkylboron compounds starting from easily preparable alkylboron compounds, by tandem addition of B-α-chiral organocopper species to allyl phosphates. The keys to successful transformation are (1) highly regio- and enantioselective hydrocupration to borylalkenes and (2) subsequent asymmetric C?C bond formation with high efficiency. They believe this protocol provides easy access to chiral secondary homoallylic alkylboron compounds and efforts to expand the use of B-α-chiral organocopper species in catalytic bond formations are currently underway.
- No. 27
- 2018-07-05
- 3421
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Simple and Disposable Biosensors for Point-of-care Applications
Nanoparticle polymer composites have wideranging applications in fields such as catalysis, optoelectronics, drug delivery and biochemical sensing. In recent years, the use of noble metal nanoparticle polymer composites for plasmonic sensing has attracted much attention, including several fabrication methodologies for such nanocomposites for the development of a substantial collection of plasmon-active sensing devices. One of the greatest advantages of nanoparticle polymer composites on solid substrates is their convenient utilization in practical applications, as they can be readily produced on gold and silicon substrates, glass, and even paper. This makes them more suitable than solution phase nanoparticle polymer composites for device integration, bringing them closer to commercialization and consumer use. To facilitate rapid technology transfers in the near future, an in-depth understanding of the subject matter as well as an update of the state-of-the-art is therefore necessary. The research team describes the assembly techniques used to obtain such nanoparticle polymer composites and their applications in plasmonic sensing based on localized surface plasmon resonance (LSPR) and surface enhanced Raman spectroscopy (SERS). Scheme 1 : Several general configurations of metal nanoparticle polymer composites discussed including nanoparticles (I) immobilized on a thin polymeric film adsorbed or spin-coated on a substrate, (II) three-dimensionally distributed within a polymer gel matrix, (III) adsorbed on polymer brush grafted-to or -from the substrate, (IV) infiltrated within the brush, (V) decorated on polymer fibers electrospun on the substrate and (VI) decorated on free-standing polymer fibers. Scheme 2 : Assembly of nanoparticles on substrate-bound polymers, categorized according to their level of mobility with respect to the underlying substrate. The nanoparticles are categorized as (I) fixated, (II) semi-fixated and (III) non-fixated.
- No. 26
- 2018-07-05
- 3382
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Successful Market Strategy of OTT Services based on Analyzation of Consumers
With the emergence of over-the-top (OTT) services, consumers can enjoy broadcasting contents using personal computers, smartphones, and tablets whenever and wherever they want. Not only are traditional broadcasting service providers entering the OTT service market, but Internet service providers are making the move too, leading to competition with each other to achieve market power. A team led by Prof. LEE of SKKU estimated consumers’ preference for OTT services based on conjoint survey data, and conducted a market simulation based on the estimation result, in order to analyze the change of market penetration ratio in accordance to the change of market strategy of each broadcasting service provider. As a result, consumers have the highest priority for real-time broadcasting. When the terrestrial television broadcasting service provider does not provide its contents to other service providers, internet service providers and pay TV service providers can increase their market power by decreasing the price and by increasing the number of VODs respectively. This study was published in the journal Technological Forecasting and Social Change in November 2016.
- No. 25
- 2018-07-05
- 3536
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Development of the Negative Differential Resistance Device for Multi-valued Logic
SKKU research team led by Prof. Jin Hong PARK successfully developed a technology for negative differential resistance devices and demonstrated a ternary inverter as a multi-valued logic application. Recently, negative differential resistance devices have attracted considerable attention due to their folded current–voltage characteristic which presents multiple threshold voltage values. Because of this remarkable property, studies associated with the negative differential resistance devices have been explored for realizing multi-valued logic applications. This study demonstrated a negative differential resistance device based on a phosphorene/rhenium disulfide (BP/ReS2) heterojunction that is formed by type-III broken-gap band alignment, showing high peak-to-valley current ratio values of 4.2 and 6.9 at room temperature, and 180 K respectively. Also, the carrier transport mechanism of the BP/ReS2 negative differential resistance device is investigated in detail by analyzing the tunneling and diffusion currents at various temperatures with the proposed analytic negative differential resistance device model. Furthermore, they demonstrated a ternary inverter as a multi-valued logic application. This research of a two-dimensional material heterojunction is a step forward towards future multi-valued logic device research. The result of the study was published in Nature Communication on Nov 7th with a thesis titled: “Phosphorene/Rhenium Disulfide Heterojunction-based Negative Differential Resistance Device for Multi-Valued Logic.”
- No. 24
- 2018-07-05
- 3868
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SKKU Professor and Team Develop Thin Film Solar Cells with High Efficiency using Pure Organic Dye
A team led by Prof. Do Hyun RYU (Dept. of Chemistry) successfully synthesized new indoline dyes which are pure organic materials, and by applying those to the thin film dye-sensitized solar cells with the thickness of the photoactive layer is less than 2 micrometers (μm), they achieved the world’s highest solar energy conversion efficiency of 9.1%. Dye-sensitized solar cells with transparency, flexibility, various colors, and indoors application capability have received many researchers’ attention, because it can be used for many applications including building integrated photovoltaic systems (BIPV). “The significance of this study is a development of new organic dye-sensitized solar cells with high efficiency at thin films. The research also presents a direction to the design of a new organic dye structure by identifying how the length of the alkyl chain attached to an organic dye which has a plane structure, affects light energy conversion efficiency”, said Prof. RYU. This study was conducted in collaboration with Prof. Tae Hyeok KWON and his team from Ulsan National Institute of Science and Technology, and published as a cover page in the Advanced Functional Materials on Oct. 10th with the title of “Photoactive Thin Films: Indoline-Based Molecular Engineering for Optimizing the Performance of Photoactive Thin Films.”
- No. 23
- 2018-07-05
- 3483
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Microfluidic Generation of Monodisperse for Floral Iridescence-inspired Structural Colorization
Encoding of structural colors in microparticles has undergone significant progress especially by confined colloidal or liquid crystal self-assembly; nevertheless, the use of these previous approaches related to confined colloidal selfassembly, have been prominently limited to 3D optical effects such as Bragg diffraction and Anderson localization. Meanwhile, various natural organisms including flowering plants (e.g.,Hibiscus Trionum flower) have advanced their colorization strategies to divide incoming white light into the spatially sequenced vivid colors, especially by using 2D grating diffractive motifs which is conformably confined onto the curvature (i.e., floral iridescence). In the work published in Advanced Materials they conceived a new idea for the artificial approach to mimicking this wonderful biological strategy and its practical application to the color encoding of colloidal particles. In particular, the monodisperse and smooth surface of photoreconfigurable microspheres produced by microfluidic technique, was deterministically textured with diverse surface relief gratings by means of “holographic photofluidization (see review paper: S. Lee et al., Adv. Mater., 24, 2069 (2012))”; the relevant optical phenomena curved surface-confined grating diffraction inspired by floral-iridescence, have been firstly detailed. Above all, it will act as an important role in greater labeling diversity of colloidal particles and better model of biologically inspired engineering not only for colloidal patching, but also for rational molding of light-flow.
- No. 22
- 2018-07-05
- 3456
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Future Electronic Devices
Multifunctional Soft Electronics Lab. (Principle investigator; Prof Tae-il Kim; School of Chemical Engineering/Department of Biomedical Engineering/Graduate School of Human ICT Convergence) is studying next-generation electronics; flexible electronics, biomimetics and bio-integrated electronics which have recently attracted attention globally. In particular, the lab are leading worldwide in related research on brain penetrating electronics (Science, 2013) and spider's sensory receptor inspired electronics (Nature 2014). The research themes of the laboratory are as follows: 1. Nanofabrication Lithography in the semiconductor industry is the most important technique, and forming small patterns is indispensable for deriving low cost, high element characteristics. This laboratory is using an unconventional method instead of light illumination. It instead utilizes a polymer mold to form a nanoscale pattern sat low cost by utilizing various natural forces (such as capillary force, adhesiveness, surface tension, etc.). We have announced a large number of patents and papers every year, including ACS Applied Materials and Interface (7, p8070, 2016). 2. Biomimetics We are imitating various natural structures with the nanofabrication technique we accomplished and aim for engineering reproduction of the unique properties. In particular, it was confirmed that adhesive strength increased several hundred times or more by mounting a gradient cilia structure of Gecko Lizard (Foot), Advanced Materials 21,p 6575 (2009). In addition, we developed nano-crack based sensors by spiders (Nature 516, p222 (2014)) and showed that it can be applied to wearable electronic devices, especially by voice signal. 3. Flexible Electronics Flexible semiconductors utilizing organic materials have been receiving the spotlight recently. However, the material itself has the disadvantage of being easy to oxidize, and there are limitations to realizing the high characteristics required in the present era. This laboratory have unique techniques for assembling inorganic thin film devices on a sheet of plastic without device degradation. High performance inorganic electronics on flexible templates can be achieved. 4. Bio-integrated Electronics We are conducting research on bio-electronics that can adhere to human skin or be inserted into the brain and organs. They can measure nerve signals or stimulate the brain with electronic devices. (Science 340, p211 (2013)). This has recently become an important starting point for the fusion research of Neuroscience and Engineering. Research on devices related to melting and disappearing in the body after operating for a certain period of time is ongoing.
- No. 21
- 2018-07-05
- 4304
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A Techonology for Enhancing Dendritic Cell-based Cancer Immunotherapy
In recent preclinical and clinical studies, the efficacy of dendritic cells (DCs)-based immunotherapy has been limited by the lack of efficient antigen loading, maturation, and poor migration rate toward lymph node of DCs. The well-designed activation of DCs by enhancing the delivery of antigens and immunostimulatory adjuvants into DCs is a key strategy for efficient cancer immunotherapy. Antigen-antibody immune complexes (ICs) are known to directly bind to and crosslink Fc-gamma receptors (FcγRs) on DCs, which induced and enhanced migration of DCs to draining lymph nodes through the up-regulation of the chemokine receptor CCR7 and cross-presentation, inducing cytotoxic T lymphocyte (CTL) response against tumor antigen. Thus, the targeting of FcγR will be a promising strategy for vaccine design and generating efficient DC-based immunotherapy of tumors. Recently, Prof. Yong Taik LIM’s group at SKKU reported that a novel nanotechnology platform that can overcome the current limitation of DCs-based cancer immunotherapy. In his group, ICs mimicking synthetic vaccine nanoparticles (NPs) were designed and successfully synthesized by the coating of poly (lactic-coglycolic acid) (PLGA) NPs containing adjuvant (CpG ODNs as TLR9 ligands) with OVA proteins (as model antigens), and by the formation of OVA-OVA antibody ICs. They also demonstrated that ICs mimicking synthetic vaccine NPs induced the effective delivery of antigen and adjuvant to DCs, which could induce powerful T cell-based immune responses and enhanced anti-tumor immunity, by the combination of FcγR-mediated enhanced uptake and immunostimulatory effect of adjuvant. Moreover, ICs mimicking synthetic vaccine NPs also stimulated DC migration toward the lymph node, which could be an alternative strategy to resolve the current limitation of DC-based immunotherapy.
- No. 20
- 2018-07-05
- 3431
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Treatment of Intractable Disease with Ultrasound and Light-controlled Nanomedicine
萌妹社区ly, chemotherapy is performed through administration of an anticancer drugs and irradiation. However, these treatments also affect normal cells as well as cancer cells, damaging the immune system in body. This is why photodynamic therapy or photothermal therapy, which can be treated only locally around cancer cells, is emerging as a new alternative for cancer therapy. Photodynamic therapy(PDT) is a treatment with photodynamic agents. The photosensitizer kills cancer cells with activated oxygen species that are activated by a laser of a specific wavelength. However, the photosensitizer remaining in the body was activated by visible light, resulting in the side effects to the normal tissues. Therefore, the patients who received the photodynamic therapy had to suffer the inconvenience of living in the dark room for a certain period of times. Photothermal therapy is a treatment using photothermal materials. The photothermal materials burns cancer cells by using heat generated by a near-infrared laser. This has attracted attention as a new treatment technique because of reduced side effects and suffering such as hair loss and so on. However, it has been difficult to utilize clinically photothermal materials because of the limitation of accurate delivery to the tumor sites. A research team led by Prof. Jae Hyung PARK has developed smart gold nanocapsules with excellent biocompatibility and tumor-targetability by applying gold to hyaluronic acid based nanoparticles. Particularly, hyaluronic acid on the surface of the capsules specifically binds to cancer cells, so that capsules in the body can actively find cancer cells. Furthermore, gold coated on the surface inhibits the indiscriminate activity of the photosensitizer caused by visible light in daily life when the nanocapsules releases heat and attacks cancer cells under laser irradiation. At this time, gold coated on the surface of the capsules is peeled off and the photosensitizer in the capsules selectively releases a large amount of reactive oxygen species to the tumor site to remove cancer cells. Prof. PARK said “This new gold nanocapsules will be used effectively and safely for cancer treatment and we will try to develop it as a core technology that can be used in clinical application.” This research was published in the world’s leading authoritative journal ACS Nano as of November 11th, with the title of “GoldNanoclustered Hyaluronan Nano-Assemblies for Photothermally Maneuvered Photodynamic Tumor Ablation.”
- No. 19
- 2018-07-05
- 3424
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‘HomeMate’, a Home Assistant Robot Invited to the World Robots on Tour Event
Founded in 2003, the Intelligent Systems Research Institute (ISRI) led by Prof. Suk Han LEE, has been involved in stateof-the-art research in robotics, computer vision, artificial intelligence, interaction science, and micro/nano systems. In the past 10 years, ISRI has been carrying out a number of major, government and industry sponsored, research projects, including cognitive visual recognition and interaction for robotic service, high precision 3D imaging for industrial automation, visual SLAM for autonomous vehicle and space rover, high quality micro imaging for medical robotics, deep learning based 3D modeling and semantic understanding, electro-hydro-dynamic nano patterning for printed electronics, to list only several. ISRI has been active globally in terms of the collaborative research, dual degree and student exchange programs with such advanced institutes as Georgia Tech, Penn State, USC, Pascal Institute, as well as Padua University. ? ??? SCI ?? 60, ?? ?? 100, ?? 60? ???? ??. (??? ????: http://isri.skku.ac.kr/) ??? ?? ?? ?? ??? ????? ??? ???? ??/????, ?? 2013? ??? ????? ?? “Robots On Tour” ??? ??? ??? ? ??? ?? “HomeMate” ? ??? ?? ??? ??? ?? ?? ??? ?? ?? ??? ???? 3?? ???? ??? ????. HomeMate ????? ??????(SKKU) ????? ???(ISRI)?? ??? ? ??? ????. ?????? ???? ????(HRI)? ?? W-????? ?? ? ??? ???? w? ??? ??? will? ????, ??? ?? ??? ?????? ??? ???? ?? ????. ??? PLANETE ROBOTS Magazine issue 24 ? ??? HomeMate ?? “UNE NOUVELLE GENERATION DE ROBOTS DE SERVICES” ????? ?? ??????? ??? ?? ?????? ????? KORUS Tech ????? ????? ? ??? ??? ??????(SKKU) ????? ???(ISRI) ??? ??? ???? ???? ?? ?? ??? ?? ??, ????, ??? ?? ???? ???? ????? ??? ?? ????? ?? ??? ??????? ?? ??? ????. ?? ?? ??? ?? ??? ?? 1?? ??? ???? ?? ???? ??? ?? ??????? ??? ?? ???? ? ??? ???? ?? ?? 3?? ???? ???? ?????. W-?? ?? ??? ????? ??? ?? ???? ??? ??? ??? ?? ? ? ??, ??? ?? ???? ??? ????? ??? ??? ???? ??? ? ??. ?? ???? ???? ??? ??, ????, ???? ?? ?? ??? ???? ??? ?? ???? ?? ???? ??? ?? ??. ???? ?? ??? ??? ???? ?? ??(HRI)? ?? w-?? ??? ?? ???? ?? ? ?? . ???? w? ??? ??? will? ????, ??? ???? ?? ?? ??? ? ?? ??? ???? ????? ????. ??? ??? ?? ?? ???? ?? ?? ??? ??? ?? ???? ?? ? ?? ??? ???? ?? ???? ??? ????? ???? ?????. W-?? ?????? ??? ????? ?? ??? ?? ??? ?? ???, ??? ???? ????? ?????? ??? ?? ???? ?? ??, ??? ??? ??? ???? ??? ?? ??, ??? ????? ???? ???? ??. ????? ??? ?? ??? ???? 3?? ??? ???? ??? ??? ?? ???? ???? ????? ??? ???? ??? ???? ????. ??? ??? ?? ? ??? ??? ???? ???? ???? ??? ? ??. ?? ???? ???, ??? ???? ??? ??? ? ??. ?? ???? ?? ???? ??? ??? ? ??. ?? ???? ??? ?? ???? ???? ??? ? ??. ?? ???? ?? ???, ??? ??, ????, ?? ??, ?? ??? ??? ?? ?? ??? ?? ? ??. ????? ?? ?? ?? ??? ??? ???, ?????, ??? ? ?? ????? ???? ??? ??? ???? ??? ???? ????. ??/??? 3?? ??? ??? Compact ???, ??? ?? ??? ?? 3?? ???? 3?? ??? ???? 3D Reconstruction? ????, ?? ??/?? ???? ???? ?? ??? ??? ???? ??? ? ??. ????? ???? ???? ????? ???? ???, ?? KIST?? ??? ?? ???? ??.
- No. 18
- 2018-07-05
- 6981
