Development of fish skin-derived composite material-based bioinks and porous collagen bioinks
School of Medicine/Department of Precision Medicine, Prof. GeunHyung Kim, SeoYul Jo, YoungWon Koo
Medicine KIM, GEUNHYUNG Prof. · SeoYul Jo, YoungWon Koo
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Advanced Materials Science and Engineering YOON, DAEHO Prof.
Production of Nanoparticle & Fabrication of New Materials by Controlling Multifunctional Structure
1. Long-term stable stacked CsPbBr3 quantum dot films for highly efficient white light generation in LEDs. In recent years, how to express colors more vividly and naturally has been raised as a major issue among researchers in the field of display. Producing colors is decided according to the light emitting spectrum of each light emitting diodes (LEDs) presenting red, green, blue. If the light emitting spectrum has narrow full width at half maximum (FWHM), the purity of light emitting material will be improved which can produce more vivid images close to the nature’s colors when applying to display. The research team proposed an efficient and simple method to improve the stability of CsPbBr3 perovskite QDs and developed highly efficient white LED. They successfully prepared fully inorganic CsPbBr3 perovskite QD films as the green-emitting luminescence material for white light generation. This article was published in 2016’s November edition of the world renowned scientific journal, Nanoscale. 2. Mesoporous Ni–Fe oxide multi-composite hollow nanocages for efficient electrocatalytic water oxidation reactions As a clean and sustainable technique, electrochemical water splitting could supply a large-scale hydrogen source. The anode reaction, namely the oxygen evolution reaction (OER) is one of the main steps in electrochemical water splitting. Using a simple two-step hydrothermal method and calcination process, the research team demonstrated the synthesis of mesoporous NiO/NiFe2O4 multi-composite hollow NCs via Ni3[Fe(CN)6]2 PBA nanocube precursors. Such mesoporous NiO/NiFe2O4 multi-composite hollow NCs after 1h of calcination in air at 500°C demonstrate enhanced OER activity with a remarkably low Tafel slope (58.5 mV dec-1), a low over potential of 303 mV at a current density of 10 mA cm2, and excellent cycling stability in alkaline electrolytes, superior to most reported hierarchical structures of binary transition metal oxides/hydroxides. This article was published in the Journal of Materials Chemistry A on 2017’s Feb. 28th.
- No. 33
- 2018-07-05
- 1753
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Economics CHO, JOONMO Prof.
Prof. Joon Mo CHO has been chosen for SKKU Fellowship Awardee
Prof. Joon Mo CHO has been chosen for SKKU Fellowship Awardee by publishing 42 research articles in the field of labor economics at SSCI Journal, and receiving recognition for his outstanding performance. There are several researches representing his work over the past 4 years and are introduced as follows: (1) Jobs in the Bureaucratic Afterlife: A Corruption-Facilitating Mechanism Associated with Law Enforcement (with Iljoong Kim), Southern Economic Journal, vol. 68, 2001 This article starts with an observation that the employment of former regulatory officers by a regulated firm might be an integral part of the corruption-facilitating mechanism (CFM). The article hypothesizes that such employment constitutes the deferred payment for the corruption previously supplied. Although anecdotal evidence of this kind of corruption abounds, it has proven difficult to substantiate. The article provides an explanation for why this deferred payment arrangement might be attractive to both demanders and suppliers of corruption. It also offers tentative empirical support for the hypothesis that it plays a role as CFM in Korea, with the implication that this CFM hypothesis can be generalized to a host of regulatory countries. (2) “Why do good performing students highly rate their instructors?”, Economics of Education Review, vol. 49, 2015 This article analyzes the behavior of students in a college classroom with regard to their evaluation of teacher performance. As some students are randomly able to see their grades prior to the evaluation, the “natural” experiment provides a unique opportunity for testing the hypothesis as to whether there exists a possibility of a hedonic (implicit) exchange between the students’ grades and teaching evaluations. Students with good grades tend to highly rate the teaching quality of their instructors, in comparison with those who receive relatively poor grades. This study finds that students with better grades than their predicted grades provide a psychological “gift” to their teachers by giving a higher teacher evaluation; whereas the opposite occurs with those students receiving lower grades than their predictions. These empirical results demonstrate that a previous interpretation on the effect of student grades in an incumbent course with regard to the teaching quality may have to be somewhat discounted. (3) “The impact of epidemics on labor market: Identifying victims of the Middle East Respiratory Syndrome in the Korean labor market”, International Journal for Equity in Health, vol. 15, 2016 The vulnerability approach suggests that disasters such as epidemics have different effects according not only to physical vulnerability, but also to economic class (status). This paper examines the effect of the Middle East Respiratory Syndrome epidemic on the labor market, to investigate whether vulnerable groups become more vulnerable due to an interaction between the socio-economic structure and physical risk. This paper examines the effect of the Middle East Respiratory Syndrome epidemic on the labor market by considering unemployment status, job status, working hours, reasons for unemployment and underemployment status. In particular, the study investigates whether the U-shaped curve becomes a J-shaped curve due to the interaction between medical vulnerability and labor market vulnerability after an outbreak, assuming that the relative vulnerability in the labor market by age shows a U curve with peaks for the young group and middle aged and old aged groups using the Economically Active Population Survey. We use the difference in difference approach and also conduct a falsification check and robustness check. The results suggest that older workers faced a higher possibility of unemployment after the Middle East Respiratory Syndrome outbreak. In particular, they experienced higher involuntary unemployment and underemployment status as well as decreased working hours. It was confirmed that the relative vulnerability of the labor market for older workers was higher than for the other age groups after the epidemic outbreak due to the double whammy of vulnerability in the medical and labor market. The vulnerability in the young group partially increased compared to the 30s and 40s age groups due to their relative vulnerability in the labor market despite being healthy. We find that assuming the relative vulnerability in the existing labor market shows a U shape with age increase, the U-shaped curve became J-shaped after the outbreak. Disasters like epidemics can occur unexpectedly and affect certain groups more than other. Therefore, medical protection should be enhanced for groups vulnerable to disease, and economic measures are also required for the protection of their livelihoods in the labor market to prevent unemployment stemming from inequality.
- No. 32
- 2018-07-05
- 2331
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SKKU Advanced Institute of Nano Technology CHO, JEONG HO Prof.
Stretchable and Multimodal All Graphene Electronic Skin
Prof. Jeong Ho CHO’s group (Organic Electronic Device Lab) at SAINT demonstrated all graphene–based transparent and conformable multifunctional E–skin matrix. The CVD–graphene was used as electrodes in the matrix, while graphene oxide (GO) and reduced graphene oxide (rGO) were adopted as sensing materials. A simple lamination process dexterously integrated humidity, temperature, and pressure sensors as a whole. Each sensor was sensitive to its relevant external stimulus, but not affected by the other two stimuli. Moreover, all the sensors can work simultaneously and indicate different stimulations individually. The distributions of the temperature, humidity, and pressure under figure pressing were represented in 2D color mapping. This work suggested a facile fabrication process combined with graphene derivatives to transparent and conformable E–skin application which overcome the conventional complex E–skin fabrication process. Additional sensors and wireless communication units could also be integrated through this simple lamination process, which would greatly help to realize interactive and remote health care in the future. Utilization of various graphene derivatives as main components in E–skin could also open up a way to accelerate the industrialization of graphene. This work was published in Advanced Materials (2016).
- No. 31
- 2018-07-05
- 2077
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Chemical Engineering PARK, HOSEOK Prof.
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. 30
- 2018-07-05
- 1768
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Energy Science KIM, SUNG WNG Prof.
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. 29
- 2018-07-05
- 1676
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Chemistry YUN, JAESOOK Prof.
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. 28
- 2018-07-05
- 1800
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Chemical Engineering KIM, DONG HWAN Prof.
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. 27
- 2018-07-05
- 1747
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Interaction Science LEE, DAEHO Prof.
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. 26
- 2018-07-05
- 1720
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Electronic and Electrical Engineering PARK, JIN HONG Prof.
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. 25
- 2018-07-05
- 2034
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Chemistry RYU, DOHYUN Prof.
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. 24
- 2018-07-05
- 1731
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Chemical Engineering YOO, PILJIN Prof.
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. 23
- 2018-07-05
- 1753
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Chemical Engineering KIM, TAE IL Prof.
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. 22
- 2018-07-05
- 1907