Latest Research News
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High-Performance and High-Reliability Artificial Synaptic Semiconductor Device Regarding Next-Generation Brain-Mimicking
- KIST discovered critical variables to maximize the performance of artificial synaptic devices - Green light for next-generation neuromorphic system development Neuromorphic computing system technology mimicking the human brain has emerged and overcome the limitation of excessive power consumption regarding the existing von Neumann computing method. A high-performance, analog artificial synapse device, capable of expressing various synapse connection strengths, is required to implement a semiconductor device that uses a brain information transmission method. This method uses signals transmitted between neurons when a neuron generates a spike signal. However, considering conventional resistance-variable memory devices widely used as artificial synapses, as the filament grows with varying resistance, the electric field increases, causing a feedback phenomenon, resulting in rapid filament growth. Therefore, it is challenging to implement considerable plasticity while maintaining analog (gradual) resistance variation concerning the filament type. The Korea Institute of Science and Technology (KIST, President Yoon Seok-jin), led by Dr. YeonJoo Jeong’s team at the Center for Neuromorphic Engineering, solved the limitations of analog synaptic characteristics, plasticity, and information preservation, which are chronic obstacles regarding memristors, neuromorphic semiconductor devices. He announced the development of an artificial synaptic semiconductor device capable of highly reliable neuromorphic computing. The KIST research team fine-tuned the redox properties of active electrode ions to solve small synaptic plasticity hindering the performance of existing neuromorphic semiconductor devices. Furthermore, various transition metals were doped and used in the synaptic device, controlling the reduction probability of active electrode ions. It was discovered that the high reduction probability of ions is a critical variable in the development of high-performance artificial synaptic devices. Therefore, a titanium transition metal, having a high ion reduction probability, was introduced by the research team into an existing artificial synaptic device. This maintains the synapse’s analog characteristics and the device plasticity at the synapse of the biological brain, approximately five times the difference between high and low resistances. Furthermore, they developed a high-performance neuromorphic semiconductor that is approximately 50 times more efficient. Additionally, due to the high alloy formation reaction concerning the doped titanium transition metal, the information retention increased up to 63 times compared with the existing artificial synaptic device. Furthermore, brain functions, including long-term potentiation and long-term depression, could be more precisely simulated. The team implemented an artificial neural network learning pattern using the developed artificial synaptic device and attempted artificial intelligence image recognition learning. As a result, the error rate was reduced by more than 60% compared with the existing artificial synaptic device; additionally, the handwriting image pattern (MNIST) recognition accuracy increased by more than 69%. The research team confirmed the feasibility of a high-performance neuromorphic computing system through this improved the artificial synaptic device. Dr. Jeong of KIST stated, “This study drastically improved the synaptic range of motion and information preservation, which were the greatest technical barriers of existing synaptic mimics.” “In the developed artificial synapse device, the device’s analog operation area to express the synapse’s various connection strengths has been maximized, so the performance of brain simulation-based artificial intelligence computing will be improved.” Additionally, he mentioned, “In the follow-up research, we will manufacture a neuromorphic semiconductor chip based on the developed artificial synapse device to realize a high-performance artificial intelligence system, thereby further enhancing competitiveness in the domestic system and artificial intelligence semiconductor field.” Image [Figure 1] Concept image of the article [Figure 2] Example of visual information processing technology using the artificial synaptic device, confirming that the error rate is reduced by more than 60% by improving the device performance [Figure 3] Photographs of (a) Solar Energy Collector, (b) Membrane Distillation System
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- WriterDr. Jeong, YeonJoo
- 작성일2022.09.16
- Views967
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Discovery of the Causes of Brain Dysfunction in Patients with Huntington’s Disease
- A protein crucial to synaptic function in brain tissues of patients with Huntington’s disease (HD) was discovered to have decreased function by researchers at KIST Huntington’s disease (HD) is a hereditary brain disease caused by a mutation in the huntingtin gene. HD is a neurodegenerative disease without a cure that, after the onset of the disease at around 40 years of age, causes changes in personality and symptoms of dementia along with uncontrollable convulsive movements, ultimately leading to death. It is known that such HD symptoms are caused by the destruction of brain cells in the striatum due to problems occurring in synapses that are crucial to brain function during the progression of the disease. However, the specific mechanism behind brain dysfunction during the progression of HD has not been fully elucidated. The research team lead by Dr. Jihye Seong and Dr. Hoon Ryu, principal researchers at the Brain Science Institute (BSI) of Korea Institute of Science and Technology (KIST, President Seokjin Yoon), was said to have found significantly reduced activity of focal adhesion kinase (FAK) proteins that play an important role in neurite motility and proper synapse formation in the brain tissues of patients with HD. Activated FAK proteins play an important role in brain function as they are essential in neurite motility and proper synapse formation. The KIST research team identified a significant reduction in FAK activity in HD cells and mouse models, as well as brain tissues of HD patients. These results were also verified through accurate measurements of FAK activity in live cells using a fluorescence resonance energy transfer (FRET)-based biosensor. Phosphatidylinositol 4,5-biphosphate (PIP2), a phospholipid found in the cell membrane, is essential for the activation of FAK proteins. Using super-resolution structured illumination microscopy, the research team found that PIP2 in HD cells was unusually strongly bound to the mutant huntingtin protein, inhibiting proper distribution of PIP2 throughout the cell membrane. This abnormal distribution of PIP2 inhibits FAK activation, which hinders proper synaptic function, causing brain dysfunction in the early stages of HD. Dr. Seong said, “The pathological mechanisms of synaptic dysfunction in patients with Huntington’s disease revealed through this study could be utilized as a therapeutic target for the treatment of brain dysfunction.” Dr. Ryu said, “Because the results of this study show the pathological mechanisms found in actual brain tissues of patients with HD, I believe it has a greater significance in suggesting a new therapeutic target for human degenerative brain diseases.” Image [Figure 1] Differences in FAK activation and neuronal protrusion formation in brain tissues of normal and Huntington's disease patients [Figure 2] Inhibition of FAK activation due to abnormal distribution of phospholipid caused by mutant huntingtin
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- WriterDr. Seong, Jihye
- 작성일2022.09.16
- Views706
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Uncovering the secrets of lithium-ion battery degradation
- KIST identified lithium ion migration pathways by using a self-designed one-stop battery analysis platform - The mechanism of anode material expansion/deterioration was confirmed… Proposing a new direction for material design to ensure stability and high-efficiency Amid global efforts towards carbon neutrality, automakers all over the world are actively engaged in research and development to convert internal combustion engine vehicles into electric vehicles. Accordingly, competition to improve battery performance, which is at the heart of electric vehicles, is intensifying. Since their commercialization in 1991, lithium-ion batteries have held a dominant market share in most market segments, from small home appliances to electric vehicles, thanks to continuous improvement in energy density and efficiency. However, some phenomena occurring within such batteries are still not well understood, such as the expansion and deterioration of the anode material. The Korea Institute of Science and Technology (KIST, President Seok-Jin Yoon) announced that its team led by Dr Jae-Pyoung Ahn (Research Resources Division) and Dr Hong-Kyu Kim (Advanced Analysis and Data Center) has succeeded in the real-time observation of the expansion and deterioration of the anode material within batteries due to the movement of lithium ions. The performance and lifespan of lithium-ion batteries are generally known to be affected by various changes that occur in the internal electrode materials during the charging and discharging processes. However, it is, difficult to monitor such changes during operation because major battery materials, such as electrodes and electrolytes, are instantly contaminated when exposed to the air. Therefore, accurate observation and analysis of structural changes in the electrode material during lithium ion migration is the most important factor in improving performance and safety. In a lithium-ion battery, the lithium ions move to the anode during charging and move to the anode during discharging. The KIST research team succeeded in real-time observation of a silicon–graphite composite anode, which is being studied for its commercial use as a high-capacity battery. Theoretically, the charging capacity of silicon is 10 times higher than that of graphite, a conventional anode material. However, the volume of silicon nanopowders quadruples during the charging process, making it difficult to ensure performance and safety. It has been hypothesized that the nanopores formed during the mixing of the constituents of silicon–graphite composites can accommodate the volume expansion of silicon during battery charging, thereby changing the battery volume. However, the role of these nanopores has never been confirmed by direct observation with electrochemical voltage curves. Using a self-designed battery analysis platform, The KIST research team directly observed the migration of lithium ions into the silicon–graphite composite anode during charging, and identified the practical role of the nanopores. It was found that lithium ions migrate sequentially into the carbon, nanopores, and silicon in the silicon–graphite composite. Furthermore, the research team noted that the nano-sized pores tend to store lithium ions (fore-filling lithiation) before the lithium-silicon particles (Si lithiation), while the micro-sized pores accommodate the volume expansion of silicon as previously believed. Therefore, the research team suggests that a novel approach that appropriately distributes micro- and nano-sized pores to alleviate the volume expansion of silicon, thereby improving the safety of the material, is necessary for the design of high-capacity anode materials for lithium-ion batteries. “Just as the James Webb Space Telescope heralds a new era in space exploration, the KIST battery analysis platform opens new horizons in material research by enabling the observation of structural changes in electric batteries,” said Dr Jae-pyeong Ahn, head of KIST Research Resources Division. "We plan to continue the additional research necessary for driving innovations in battery material design, by observing structural changes in battery materials that are not affected by atmospheric exposure." he said. This work was supported by the Ministry of Science and ICT (Minister Jong-Ho Lee) as part of the Nano Material Source Technology Development Project of the Korea National Research Foundation (NRF), and the Creative Convergence Research Project of the Korea National Research Council of Science and Technology (NST). The research results were published in the latest issue of the ‘ACS Energy Letters (IF: 23.991, top 3.21% of JCR), an international academic journal in the field of batteries. [Figure 1] Schematic diagram of KIST Battery Analysis Platform [Figure 2] Scanning Electron Microscopy (SEM) images of lithium migration
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- WriterResearch Resources Division
- 작성일2022.09.14
- Views710
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Preparing for Water Scarcity using Hybrid Desalination Technologies
- KIST develops membrane distillation methods using hydrothermal and solar energy - The goal is to maximize system efficiency through customized membrane distillation technologies for regional climate characteristics Clean water is essential for human survival. However, less than 3% of fresh water can be used as drinking water. According to a report published by the World Meteorological Organization, there is scarcity of drinking water for approximately 1 billion people worldwide, which is expected to rise to 1.4 billion by 2050. Seawater desalination technology, which produces fresh water from seawater, could solve the problem of water scarcity. At the Korea Institute of Science and Technology (KIST, President: Seok-Jin Yoon), a research team led by Dr. Kyung Guen Song from the Center for Water Cycle Research, have developed a hybrid membrane distillation module that combines solar energy with hydrothermal heat pumps to reduce thermal energy consumption during the desalination process. Reverse osmosis and evaporation methods are relatively common seawater desalination processes; however, these methods can operate only at high pressures and temperatures. In comparison, the membrane distillation method produces fresh water by utilizing the vapor pressure generated by the temperature difference between the flowing raw water and treated water separated by a membrane. This approach has the advantage of low energy consumption, as fresh water can be generated at pressures of 0.2–0.8 bar, which is lower than atmospheric pressure, and temperatures of 50–60℃. However, large scale operation requires more thermal energy. Thus, research studies are required to reduce the use of thermal energy for commercial operation. The membrane distillation involves simultaneous mass and heat (energy) transfer. It is divided into a direct contact membrane distillation (DCMD) and an air gap membrane distillation (AGMD) based on the modes applied to the treated water side of membrane to generate vapor pressure differences, which are the driving force. For high energy supply, the mode of producing water by direct contact of raw water of high temperature and treated water of low temperature to the membrane surface (i.e., DCMD) is beneficial. In contrast, for low energy supply, the efficiency is greater if the heat transmitted (heat loss) is reduced by air gaps, rather than direct contact between raw water and processed water (see Figure 1). Thus, the mode that generate water by condensing over a cold surface and which maintain air gaps between the membrane and the condensation surface (i.e., AGMD) are preferred. The KIST Research Team developed a hybrid desalination technology by conducting on-site tests for 1 month to compare the system performance and economy using solar energy and hydrothermal heat pumps. When the system operated in parallel with solar energy, production increased by 9.6% (see Figure 2) and energy usage was reduced by 30% (see Figure 3) compared to the membrane distillation method using only hydrothermal heat pumps. In addition, comparison of the consumption of thermal energy depending on the presence of solar energy showed that the efficiency of the membrane distillation plant process increased by up to 17.5% when solar energy was used as an additional heat source. According to Dr. Song, “The hybrid desalination technology we developed can be considered a method to supply water to some industrial complexes and island areas facing water scarcity as it can reduce the energy consumption required to generate fresh water. We expect this technology to be applied to significant water supply facilities in the Middle East and Southeast Asia where the annual solar radiation quantity is 1.5 times that in Korea." He added, “Membrane distillation is not significantly affected by raw water quality, so it will be possible to supply drinking water to areas where raw water quality became heavily contaminated due to water pollution and areas where heavy metal detection is high." Image [그림 1] Comparison of Production Volume and Efficiency for Different Membrane Distillation Compositions [그림 2] Comparison of Specific Energy Consumption (SEC) and Gain Output Ratio (GOR) with Weather in Hybrid Systems [그림 3] Photographs of (a) Solar Energy Collector, (b) Membrane Distillation System
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- WriterDr. Song, Kyung Guen
- 작성일2022.08.26
- Views613
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Damage-reporting and Self-healing Skin-like Polymeric Coatings
- Self-reporting and self-healing coatings similar to human skin - High re-usability of coating reduces waste generation by maintaining functionality Skin-like polymeric coatings are applied to the surfaces of automobiles, ships, and buildings to protect them from the external environment. As it is difficult to determine whether the currently used coatings are already damaged or not, these non-reusable coatings must be regularly replaced, leading to a large amount of waste generation and high disposal costs. The Korea Institute of Science and Technology (KIST, President Seok-Jin Yoon) announced that Dr. Tae Ann Kim’s team at the Soft Hybrid Materials Research Center has developed a polymeric coating wherein the damaged area changes color, enabling immediate detection and high temperature self-healing. Existing studies on damage-reporting and self-healing polymeric coatings involve the use of extremely small capsules containing functional agents. However, these capsules cannot be used again for subsequent damage detection and self-healing if broken. The KIST research team has developed a thermoset polymer that can recover its original chemical structure after being disrupted by an external stimulus, thereby allowing this material to self-report damage and self-heal multiple times. In this study, a mechanochromic molecule, which changes color when an external force is applied due to a specific bond cleavage, and a thermoset polymer containing a molecule that can be separated and re-formed by temperature were synthesized. When a force is applied to a mechanochromic molecule, a certain bond is broken, thus changing into a form that can exhibit color. The damaged part of the synthesized polymeric coating changed to purple. When a temperature of 100 °C or higher was applied, the material became processable and was physically healed and became colorless. The research team used molecular dynamics simulations to predict and confirm that only certain desired chemical bonds are selectively cleaved when a mechanical force is applied to yield a colored structure; the functionality was implemented by synthesizing the actual coating agent. The novel multifunctional polymeric coating developed herein can be extensively used in automotive, marine, defense, timber, railway, highway, and aerospace industries, and can significantly contribute toward the reduction of industrial waste. In addition, it can be used as an artificial skin for robots, such as humanoids, since its functionality is similar to that of skin and it does not require an external energy source. Dr. Tae Ann Kim of KIST said, “This study reports a method for the simultaneous realization of damage detection and self-healing technology without any external agents such as capsules.” He added, “However, even if repeated self-healing is possible, it cannot be used permanently. Therefore, additional research is underway to transition materials that have reached their lifespan into materials that are harmless to the environment or convert them into a re-cyclable form.” [Image] [Fig. 1] Schematic of mechanochromic and self-healing thermosets [Fig. 2] Mechanochromic and self-healing coatings on diverse substrates
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- WriterDr. Kim, Tae Ann
- 작성일2022.08.25
- Views549
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KIST Developed a core technology for Aqueous Zinc Batteries
- Expected to replace lithium-based energy storage systems that have a high risk of explosions with aqueous zinc batteries. Successful growth and optimization of zinc metal anodes through low-cos and ecofriendly electroplate processes. Most energy storage systems (ESSs) have recently adopted lithium-ion batteries (LIBs), with the highest technology maturity among secondary batteries. However, these are argued to be unsuitable for ESSs, which store substantial amounts of electricity, owing to fire risks. The instability of the international supply of raw materials to construct LIBs has also emerged as a crucial concern. By contrast, aqueous zinc-ion batteries (AZIBs) use water as the electrolyte, which fundamentally prevents battery ignition. Furthermore, the price of zinc, the raw material, is only one-sixteenth of that of lithium. The research team led by Dr. Minah Lee at the Energy Storage Research Center in the Korea Institute of Science and Technology (KIST; President Seok-Jin Yoon) announced that they had succeeded in developing a technology for manufacturing “high-density zinc metal anodes,” which is key to commercializing AZIBs. This manufacturing technology is expected to act as a catalyst for the mass production of AZIBs because zinc metal anodes with high energy density and long lifespan can be produced through a simple electroplating process by using low-cost and ecofriendly solutions. In theory, because AZIBs utilize two electrons per ion, they are advantageous in terms of volumetric energy density relative to alkali metal-ion batteries. If the capacity of the zinc metal used as the anode for making the battery does not exceed twice that of the cathode, it is possible to realize an energy density comparable to that of the LIBs commercialized today. Furthermore, even if the capacity of the zinc metal reaches five times that of the cathode, it is still competitive in that it is similar to that of sodium-ion batteries, which are attracting attention as the next generation of batteries owing to their low cost and material abundance. However, zinc metal anodes restrict the energy density and lifespan of AZIBs because of the irregular growth of nanoparticles during battery operation. A low zinc metal particle density and a large surface area in the anode accelerate corrosion with the electrolyte, thus depleting the active zinc metal and the electrolyte. Existing studies have typically used zinc metals that were 20 times thicker than what was required to counteract the lifespan limitations; paradoxically, this led to an inevitable decline in energy density and cost competitiveness, the biggest strengths of AZIBs. Thus, the team led by Dr. Minah Lee at the KIST controlled the microstructure of zinc metal anodes to reduce the prevalence of the side reactions that induce the decline in energy density and lifespan of AZIBs. The team adopted a deep eutectic solvent (DES) solution, which can be easily synthesized at room temperature, was to construct the compact zinc anodes. This DES solution is composed of choline chloride and urea mixed at a mole ratio of 1:2; the mixture becomes a liquid complex with a melting point of 12 °C. The researchers confirmed that a zincophilic copper–zinc alloy layer spontaneously forms between the zinc and copper current collectors within the DES, enabling high-density zinc particles to grow. The researchers succeeded in using this discovery to develop an electroplating process that allows zinc metals to grow densely and evenly in the low-cost and ecofriendly DES solution. Application of the manufactured zinc metal anode to an aqueous zinc battery system showed that the corrosion reactions are effectively suppressed, and the capacity is maintained at more than 70% after more than 7000 repeated charges and discharges. This result is exceptional relative to those of similar existing studies that utilized thin zinc, and the values far exceed the charging and discharging lifespans (1000–2000 times) of commercial LIBs. Dr. Minah Lee of the KIST stated, “We were able to develop a core technology for commercializing AZIBs that can solve the fire safety issue of ESSs, which is the biggest obstacle to the provision and expansion of renewable energy.” She added, “We expect that this compact zinc anode manufacturing technology will open the way for the mass production of AZIBs by combining a particularly economical and ecofriendly DES solution with an electroplating process already widely used throughout the industry.” - Image Unlike zinc particles, which are irregularly formed in a conventional aqueous electrolyte and induce corrosion, zinc grown in a DES solution is tight and uniform and maintains a stable structure even after charging and discharging in an aqueous electrolyte
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- WriterDr. Lee, Minah
- 작성일2022.07.26
- Views716
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KIST develops key technology for quantum cryptography commercialization
- World’s second successful demonstration of Scalable TF QKD network structure In modern cryptosystems, users generate public and private keys that guarantee security based on computational complexity and use them to encrypt and decrypt information. However, recently, modern public-key cryptosystems have faced potential security loopholes against quantum computers with great computational power. As a solution, quantum cryptosystems have been highly noticed. They use quantum keys that guarantee security based on quantum physics rather than computational complexity, thus they are secure even against quantum computers. Therefore, quantum cryptosystems are expected to replace modern cryptosystems. Quantum key distribution (QKD) is the most important technology for realizing quantum cryptosystems. Two main technical issues should be addressed to commercialize QKD. One is the communication distance, and the other is the expansion from one-to-one (1:1) communication to one-to-many (1:N) or many-to-many (N:N) network communication. Twin-field (TF) QKD, announced in 2018, is a long-distance protocol, which can dramatically increase the communication distance of QKD systems. In TF QKD, two users can distribute a key by transmitting quantum signals to an intermediate third-party that is for measurement. Given the inevitable channel loss, this architecture allows the users to increase the communication distance. However, despite its innovativeness, it has been experimentally demonstrated by only a few global QKD leading groups owing to the significant difficulty of system implementation, and research on the TF QKD network is still insufficient. The Korea Institute of Science and Technology (KIST, Director Seok-jin Yoon) announced that their research team, the Center for Quantum Information, led by director Sang-Wook Han, succeeded in an experimental demonstration of a practical TF QKD network. This is the second experimental demonstration of the TF QKD network in the world after the University of Toronto in Canada. The research team proposed a new TF QKD network structure scalable to a two-to-many (2:N) network based on polarization-, time-, and wavelength-division multiplexing. Unlike the first demonstration of the University of Toronto based on a ring network structure, the research team's architecture is based on a star network. The quantum signal in a ring structure must pass through every user connected to the ring, however, the star structure only has it go through the center, making it possible to implement a more practical QKD system. Besides, to overcome the main implementation obstacles to developing the TF QKD system, the team applied a plug-and-play (PnP) structure. A conventional TF QKD system requires many control systems, such as timing, wavelength, phase, and polarization controllers, to maintain the indistinguishability of two quantum signals emitted by two users’ different light sources. Whereas in the PnP TF QKD architecture developed by the KIST research team, the middle third-party generates and transmits the initial signals to both users using a single light source, and the signals return to the third-party by making a round trip. Therefore, the polarization drift due to the birefringence effect of the channel is automatically compensated, and users have fundamentally the same wavelength. In addition, due to the two signals passing through the same route in opposite directions, the arrival times of the signals are naturally identical. As a result, only a phase controller is required for implementing the research team's architecture. Based on the architecture, the team successfully conducted an experimental demonstration of a TF QKD network. "It is a significant research achievement showing the possibility of solving the two main obstacles to QKD commercialization, and we have gained a key technology leading the corresponding research," said Sang-Wook Han, the leader of the Center for Quantum Information. - Image 2:N TF QKD network structure
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- WriterDr. Han, Sang-Wook
- 작성일2022.07.23
- Views884
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Rewriting the history of K-carbon fiber manufacturing with carbon nanotubes
- Projected to create the next growth engine for the aerospace and defense industries, providing a gateway for Korea to become a materials superpower A space elevator, a technology connecting the Earth’s surface to a space station, would allow for the cost-efficient transport of people and materials. However, a very light yet strong material is essential to making such a technology a reality. The carbon nanotube is a new kind of material that is 100 times stronger, yet four times lighter, than steel, with copper-like high electrical conductivity and diamond-like thermal conductivity. However, previous carbon nanotube fibers were not ideal for extensive use, owing to the small contact area with adjacent carbon nanotubes and limited length they possessed. A research team led by Dr. Bon-Cheol Ku at the Korea Institute of Science and Technology (KIST; President: Seok-Jin Yoon) Jeonbuk Institute of Advanced Composite Materials in South Korea announced that it had developed an ultra-high-strength and ultra-high-modulus carbon nanotube fiber material through a joint research project with Professor Seongwoo Ryu’s research team at Suwon University (President: Chul-Su Park) in South Korea, and Dr. Juan José Vilatela from the IMDEA Materials Institute in Spain. Existing polyacrylonitrile (PAN)-based carbon fibers have high strength and a low modulus, whereas pitch-based carbon fibers have low strength and a high modulus. Previous studies on simultaneously improving the tensile strength and modulus of carbon fibers only focused on adding a small amount of carbon nanotubes. However, the KIST, Suwon University, and IMDEA joint research team produced fibers entirely consisting of carbon nanotubes without using the conventional carbon fiber precursors, polymer and pitch. The team manufactured high-density, high-alignment carbon nanotube fibers through a wet-spin manufacturing process suitable for mass production and then annealed them at high temperatures to enable their structures to be converted into various specific types, including graphite. Accordingly, the contact areas of the carbon nanotubes increased. These carbon nanotube fibers produced in such a way are expected to have various applications, as they simultaneously exhibit ultra-high strength (6.57GPa) and an ultra-high modulus (629GPa) characteristics, which could not be achieved with conventional carbon fibers. The fibers also showed high knot strength, indicating flexibility (Figure 2). Dr. Bon-Cheol Ku commented, “K-carbon fiber manufacturing technology using carbon nanotube materials is what will enable South Korea, a latecomer to the carbon fiber field, to lead the industry. This important technology will serve as the future growth engine for the aerospace and defense industries which is needed to propel South Korea into the realm of materials superpowers.” He continued, “We have secured the original technology for manufacturing carbon nanotube-based ultra-high strength and ultra-high modulus carbon fibers, but in order for the mass production of ultrahigh performance carbon fibers to be possible, the mass production of double-walled carbon nanotubes, a core material, must happen first,” stating that support on the national level as well as industry interest are needed to further progress. - Image Schematic of the structural changes of carbon nanotubes at different annealing temperatures
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- WriterDr. Ku, Bon-Cheol
- 작성일2022.07.21
- Views397
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CO2→ formate conversion technology with significantly improved production rate
- Enhancement four times the conventional production rate, 100 times the durability compared to conventional commercial electrodes. - High potential use for LOHC hydrogen reservoir. "Carbon dioxide as a resource" and "hydrogen energy utilization" are considered to be the most practical measures to realize carbon neutrality. However, technological innovation is essential for them to be feasible both environmentally and economically. To this end, a Korean research team developed a proprietary technology that harnesses the synergy of both fields: "carbon dioxide as a resource" and "hydrogen energy utilization." The Korea Institute of Science and Technology (KIST; President: Seok-Jin Yoon) reported that the research group of Dr. Hyung-Suk Oh at the Clean Energy Research Center has developed a technology that stably converts carbon dioxide into useful liquid compounds (formate) by performing high-volume synthesis with fluorine-doped tin oxide catalysts. Also called methanoic acid, formate is a basic chemical raw material used in various industries such as food processing, preservatives, dyeing agents, plasticizers, snow removal agents, and cure retardants owing to its distinctive sour taste, anti-bacterial properties, and its ability to control pH. In recent years, it has also been in the spotlight as a raw material for eco-friendly biodegradable plastic. Because most formate is currently produced via the thermo-chemical reaction of fossil fuels, carbon dioxide emissions are inevitable during the manufacturing process. While it can be manufactured in an eco-friendly manner if carbon dioxide is directly converted into formate via an electro-chemical reaction, it would be necessary to increase electrode material performance responsible for converting the gas to a liquid phase, and to ensure durability, which allows electrodes to function stably for a long time. The KIST research team focused on the fact that fluorine-doped tin oxide has a lower tendency than regular tin oxide to metalize and maintain the carbon dioxide conversion activity of catalysts. By using a relatively simple method of doping fluorine during the synthesis of Tin oxide, the researchers developed an electrode that maintains high formate conversion activity in a stable manner. The fluorine-doped tin oxide electrode manufactured by the proposed method was shown to have a formate production rate that is four times that of an existing commercial tin oxide electrode, and its durability improved by at least 100 times, so its performance is maintained even during a long-term reaction time of over a week. Alternatively, formate is one of the most promising candidates as a liquid organic hydrogen carrier (LOHC), which is a hydrogen storage material that bonds hydrogen with a third substance to enable storage and transportation without the need to rely on expensive heavy-duty specialized containers. The core of LOHC technology is to secure liquefied compounds with high storage capacity for hydrogen and safety, even when exposed to external factors; formate has this characteristic. With the application of the technology developed by the researchers, as the environmental and economic concerns (which were previously considered weaknesses) will be resolved simultaneously, a reevaluation of its competitiveness is expected against other candidate materials such as ammonia. According to Dr. Hyung-Suk Oh, "By developing highly efficient electrodes, we can build a continuous system mass-producing formate from carbon dioxide." "Not only is this a direction for Carbon Capture, Utilization and Storage (CCUS), but also it is a "killing two birds in one stone" kind of technology that provides large amount of formate ideal for hydrogen storage. We expect it to contribute greatly to carbon neutrality in the future as the renewable energy supply increases and the hydrogen-based society advances, making the system economically feasible." - Image Production and utilization of formate with fluorine-doped tin oxide catalyst for CO2 conversion
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- WriterDr. Hyung-Suk Oh
- 작성일2022.07.19
- Views1576
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Malignant or benign? Quick and accurate diagnosis with artificial tactile neurons
- An artificial tactile neuron device that quickly and accurately converts the stiffness of a substance. - Combining with AI technology enables learning of the stiffness levels and distributions of the tumor, suggesting the possibility of cancer diagnosis. The stiffness levels and distributions of various biological materials reflect disease-related information, from cells to tissues. For example, malignant breast tumors are usually stiffer and have a more irregular shape than benign breast tumors. Ultrasound elastography can non-invasively determine the degree and shape of the tissue stiffness and is used for diagnosing breast cancer owing to its low cost. However, the opinion of an experienced expert is essential for interpreting ultrasound elastography images, but different experts differ in accuracy. The president of the Korea Institute of Science and Technology (KIST), Mr. Seok-Jin Yoon, announced that Dr. Hyunjung Yi's team at the spin convergence research center and Suyoun Lee, the director of the Center for Neuromorphic Engineering, had developed a simple but highly accurate disease diagnosis technology by combining tactile neuron devices with artificial neural network learning methods. Unlike the previously reported artificial tactile neuron devices, this tactile neuron device can determine the stiffness of objects. Neuromorphic technology is a research field that aims to emulate the human brain's information processing method, which is capable of high-level functions while consuming a small amount of energy using electronic circuits. Neuromorphic technology is gaining attention as a new data processing technology fit for AI, IoT, and autonomous driving, requiring the real-time processing of complex and vast information. Sensory neurons receive external stimuli through sensory receptors and convert them into electrical spike signals. Here, the generated spike pattern varies based on the external stimulus information. For example, higher stimulus intensity causes higher generated spike frequency. The research team developed an artificial tactile neuron device with a simple structure that combines a pressure sensor and an ovonic threshold switch device to produce such sensory neuron characteristics. Applying pressure to the pressure sensor causes the sensor's resistance to decrease and the connected ovonic switch element's spike frequency to change. The developed artificial tactile neuron device is a high-response, high-sensitivity device that allows the pressing force to generate faster electrical spikes while improving the pressure sensitivity, which focuses on the fact that stiffer materials result in faster pressure sensing when pressed. The electrical spike duration (or 1/frequency) generated by the developed device is less than 0.00001 s, which is more than 100,000 times faster than the several seconds it usually takes to press an object. Additionally, while the existing devices could detect a low pressure (approximately 20 kPa, similar to a force of light pressing) with a spike frequency change of 20 to 40 Hz, the developed device can detect the low pressure with spike frequency changes of 1.2 MHz. This allows real-time conversion of changes in the pressing force into spikes. To deploy the developed device to actual disease diagnosis, the research team used elastography images of malignant and benign breast tumors and utilized a spiking neural network learning method. Each pixel of the color-coded ultrasound elastography image which is correlated with the stiffness of the imaged material was converted into a spike frequency change value and used for training the AI. As a result, it was possible to determine the malignancy of a breast tumor with up to 95.8% accuracy. The KIST research team stated, "the developed artificial tactile neuron technology is capable of detecting and learning mechanical properties with a simple structure and method." The team added, "Through follow-up research, it will be possible to solve the noise reflection issue, which is a disadvantage of ultrasound elastography if artificial tactile neurons can collect an object's elastography image obtainable using ultrasound elastography." The team also expects the device to be helpful in low-power and high-accuracy disease diagnosis and applications such as robotic surgery where a surgical site needs to be quickly determined in an environment humans cannot directly contact." - Image The research results are published as an inside back cover paper in Advanced Materials.
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- WriterDr. Yi, Hyunjung
- 작성일2022.07.09
- Views516