research
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Materials Developed for Sodium Rechargeable Battery by EEWS
The research group of Professor William Goddard III, You-Sung Jung, and Jang-Wook Choi from the Graduate School of Energy, Environment, Water, and Sustainability (EEWS) at KAIST has developed a new sodium-ion rechargeable battery which operates at a high voltage, can be charged, and stably discharges over 10,000 cycles. The research results were published in the online version of the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on December 30, 2013.
Since the material costs of sodium rechargeable batteries is 30 to 40 times lower than lithium batteries, it has received attention as an energy saving tool for smart grids and as the next generation of lithium rechargeable batteries. Until now, sodium-ion rechargeable batteries have had issues with stability when charging and discharging. The research group developed a vanadium-based electrode to solve these problems.
The group said follow-up research will be continued to develop advanced technology on sodium rechargeable batteries as it is still currently in the beginning stages.
The research team: From left to right is Professors William Goddard, You-Sung Jung, and Jang-Wook Choi
2014.01.13 View 11420 -
Mechanism in regulation of cancer-related key enzyme, ATM, for DNA damage and repair revealed
Professor Kwang-Wook Choi
A research team led by Professor Kwang-Wook Choi and Dr. Seong-Tae Hong from the Department of Biological Sciences at KAIST has successfully investigated the operational mechanism of the protein Ataxia Telangiectasia Mutated (ATM), an essential protein to the function of a crucial key enzyme that repairs the damaged DNA which stores biometric information. The results were published on December 19th Nature Communications online edition.
All organisms, including humans, constantly strive to protect the information within their DNA from damages posed by a number of factors, such as carbonized materials in our daily food intake, radioactive materials such as radon emitting from the cement of buildings or ultraviolet of the sunlight, which could be a trigger for cancer.
In order to keep the DNA information safe, the organisms are always carrying out complex and sophisticated DNA repair work, which involves the crucial DNA damage repair protein ATM. Consequently, a faulty ATM leads to higher risks of cancer.
Until now, academia predicted that the Translationally Controlled Tumor Protein (TCTP) will play an important role in regulating the function of ATM. However, since most of main research regarding TCTP has only been conducted in cultured cells, it was unable to identify exactly what mechanisms TCTP employs to control ATM.
The KAIST research team identified that TCTP can combine with ATM or increase the enzymatic activity of ATM. In addition, Drosophilia, one of the most widely used model organisms for molecular genetics, has been used to identify that TCTP and ATM play a very important role in repairing the DNA damaged by radiation. This information has allowed the researchers to establish TCTP’s essential function in maintaining the DNA information in cell cultures and even in higher organisms, and to provide specific and important clues to the regulation of ATM by TCTP.
Professor Kwang-Wook Choi said, “Our research is a good example that basic research using Drosophilia can make important contributions to understanding the process of diseases, such as cancer, and to developing adequate treatment.”
The research has been funded by the Ministry of Science, ICT and Future Planning, Republic of Korea, and the National Research Foundation of Korea.
Figure 1. When the amount of TCTP protein is reduced, cells of the Drosophila's eye are abnormally deformed by radiation. Scale bars = 200mm
Figure 2. When the amount of TCTP protein is reduced, the chromosomes of Drosophilia are easily broken by radiation. Scale bars = 10 mm.
Figure 3. When gene expressions of TCTP and ATM are reduced, large defects occur in the normal development of the eye. (Left: normal Drosophilia's eye, right: development-deficient eye)
Figure 4. ATM marks the position of the broken DNA, with TCTP helping to facilitate this reaction. DNA (blue line) within the cell nucleus is coiled around the histone protein (green cylinder). When DNA is broken, ATM protein attaches a phosphate group (P). Multiple DNA repair protein recognizes the phosphate as a signal that requires repair and gathers at the site.
2014.01.07 View 13829 -
Success in Measuring Protein Interaction at the Molecular Level
Professor Tae Young Yoon
- Live observation of two protein interaction in molecular level successful- The limit in measurement and time resolution of immunoprecipitation technique improved by a hundred thousand fold
KAIST Department of Physics Professor Tae Young Yoon’s research team has successfully observed the interaction of two proteins live on molecular level and the findings were published in the October edition of Nature Protocols.
Professor Yoon’s research team developed a fluorescent microscope that can observe a single molecule. The team grafted the immunoprecipitation technique, traditionally used in protein interaction analysis, to the microscope to develop a “live molecular level immunoprecipitation technique”. The team successfully and accurately measured the reaction between two proteins by repeated momentary interactions in the unit of tens of milliseconds.
The existing immunoprecipitation technique required at least one day to detect interaction between two proteins. There were limitations in detecting momentary or weak interactions. Also, quantitative analysis of the results was difficult since the image was measured by protein-band strength. The technique could not be used for live observation.
The team aimed to drastically improve the existing technique and to develop accurate method of measurement on molecular level. The newly developed technology can enable observation of protein interaction within one hour. Also, the interaction can be measured live, thus the protein interaction phenomenon can be measured in depth.
Moreover, every programme used in the experiment was developed and distributed by the research team so source energy is secured and created the foundation for global infra.
Professor Tae Young Yoon said, “The newly developed technology does not require additional protein expression or purification. Hence, a very small sample of protein is enough to accurately analyse protein interaction on a kinetic level.” He continued, “Even cancerous protein from the tissue of a cancer patient can be analysed. Thus a platform for customised anti-cancer medicine in the future has been prepared, as well.”
Figure 1. Mimetic diagram comparing the existing immunoprecipitation technique and the newly developed live molecular level immunoprecipitation technique
2013.12.11 View 8366 -
The key to Alzheimer disease, PET-MRI made in Korea
Professor Kyu-Sung Cho
- Simultaneous PET-MRI imaging system commercialization technology developed purely from domestic technology - - Inspiring achievement by KAIST, National NanoFab Center, Sogang University, Seoul National University Hospital –
Hopes are high for the potential of producing domestic products in the field of state-of-the-art medical imaging equipment that used to rely on imported products.
The joint research team (KAIST, Sogang University and Seoul National University) with KAIST Department of Nuclear and Quantum Engineering Professor Kyu-Sung Cho in charge, together with National Nanofab Institution (NNFC; Director Jae-Young Lee), has developed PET-MRI simultaneous imaging system with domestic technology only. The team successfully acquired brain images of 3 volunteers with the newly developed system.
PET-MRI is integrated state-of-the-art medical imaging equipment that combines the advantages of Magnetic Resonance Imaging (MRI) that shows anatomical images of the body and Position Emission Tomography (PET) that analyses cell activity and metabolism. Since the anatomical information and functional information can be seen simultaneously, the device can be used to diagnose early onset Alzheimer’s disease and is essential in biological science research, such as new medicine development.
The existing equipment used to take MRI and PET images separately due to the strong magnetic field generated by MRI and combine the images. Hence, it was time consuming and error-prone due to patient’s movement. There was a need to develop PET that functions within a magnetic field to create a simultaneous imaging system.
The newly developed integral PET-MRI has 3 technical characteristics: 1. PET detector without magnetic interference, 2. PET-MRI integration system, 3.PET-MRI imaging processing.
The PET detector is the most important factor and accounts for half the cost of the whole system. KAIST Professor Cho and NNFC Doctor Woo-Suk Seol’s team successfully developed the Silicon Photomultiplier (amplifies light coming into the radiation detector) that can be used in strong magnetic fields. The developed sensor has a global competitive edge since it optimises semiconductor processing to yield over 95% productivity and around 10% gamma radiation energy resolving power.
Sogang University Department and Electrical Engineering Professor Yong Choi developed cutting edge PET system using a new concept of electric charge signal transmission method and imaging location distinction circuit. The creativity and excellence of the research findings were recognised and hence published on the cover of Medical Physics in June.
Seoul National University Hospital Department of Nuclear Medicine Professor Jae-Sung Lee developed the Silicon Photomultiplier sensor based PET imaging reconstitution programme, MRI imaging based PET imaging revision technology and PET-MRI imaging integration software.
Furthermore, KAIST Department of Electrical Engineering Professor Hyun-Wook Park was responsible for the development of RF Shielding technology that enables simultaneous installation of PET and MRI and using this technology, he developed a head coil for the brain that can be connected to PET for installation.
Based on the technology describe above, the joint research team successfully developed PET-MRI system for brains and acquired PET-MRI integrated brain images from 3 volunteers last June.
In particular, this system has the distinct feature of a detachable PET module and MRI head coil to the existing whole body MRI, so that PET-MRI simultaneous imaging is possible with low installation cost.
Professor Cho said, “We have prepared the foundation of domestic commercial PET and the system has a competitive edge in the global market of PET-MRI system technology.” He continued, “It can reduce the cost of the increasing brain related disease diagnosis, including Alzheimer’s, dramatically.”
Funded by Ministry of Trade, Industry and Energy as an Industrial Foundation Technology Development Project (98 billion won in 7 years), the research applied for over 20 patents and 20 CSI theses.
Figure 1.Brain phantom images from developed PET-MRI system
Figure 2. Brain images from developed PET-MRI system
Figure 3. Domestic PET-MRI clinical trial
Figure 4. Head RF coil and PET detector inserted in MRI
Figure 5. Insertion type PET detector module
Figure 6. Silicon Photomultiplier sensor (Left) and flash crystal block (right)
Figure7. Silicon Photomultiplier sensor
Figure 8. PET detection principle
2013.11.28 View 14268 -
Green Technology for Data Centers: Ultra-low Power 100 Gbps Ethernet Integrated Circuit Developed
A new integrated circuit (IC), consuming only 0.75W of electricity, will reduce the power usage of data chips installed at data centers by one-third.
Each day, billions of people surf the Internet for information, entertainment, and educational content. The Internet contains an immeasurable amount of information and knowledge generated every minute all around the world that is readily available to everyone with a click of a computer mouse. The real magic of the Internet, however, lies in data centers, where hundreds of billions of data are stored and distributed to designated users around the clock.
Today, almost every business or organization either has its own data centers or outsources data center services to a third party. These centers house highly specialized equipment responsible for the support of computers, networks, data storage, and business security. Accordingly, the operational cost of data centers is tremendous because they consume a large amount of electricity.
Data centers can consume up to 100 times more energy than a standard office building. Data center energy consumption doubled from 2000 to 2006, reaching more than 60 billion kilowatt hours per year. If the current usage and technology trends continue, the energy consumption of data centers in the US will reach 8% of the country’s total electric power consumption by 2020.
A research team at the Korea Advanced Institute of Science and Technology (KAIST) and Terasquare, Inc. (
http://www.terasquare.co.kr
), a spin-off company of the university,
developed an extremely low-powered integrated circuit for Ethernet that consumes less than 0.75W of electricity but is able to send and receive data at the high speed of 100 gigabits per second (Gbps). The research team, headed by Hyeon-Min Bae, assistant professor of electrical engineering at KAIST, claims that the new microchip uses only one-third of the electricity consumed by the currently installed chips at data centers, thereby helping the centers to save energy.
Integrated circuits are embedded on communication modules that are inserted into a line card. Data centers have numerous line cards to build a network including routers and switches. Currently, 8W ICs are the most common in the market, and they consume a lot of energy and require the largest modules (112 cm
2
of CFP), decreasing the port density of line cards and, thus, limiting the amount of data transmission.
The ultra-low-power-circuit, 100-gigabit, full-transceiver CDR, is the world’s first solution that can be loaded to the smallest communication modules (20 cm
2
of CFP4 or 16 cm
2
of
QSFP28), the next-generation chips for data centers. Compared with other chip producers, the 100 Gbps CDR is a greener version of the technology that improves the energy efficiency of data centers while maintaining the high speed of data transmission.
Professor Hyeon-Min Bae said, “When we demonstrate our chip in September of this year at one of the leading companies that manufacture optical communication components and systems, they said that our product is two years ahead of those of our competitors. We plan to produce the chip from 2014 and expect that it will lead the 100 Gbps Ethernet IC market, which is expected to grow to USD 1 billion by 2017.”
The commercial model of the IC was first introduced at the 39
th
European Conference and Exhibition on Optical Communication (ECOC), the largest optical communication forum for new results and developments in Europe, held from September 22-26 at ExCeL London, an international exhibition and convention center.
Professor Bae added, “We received positive responses to our ultra-low-power 100-Gbps Ethernet IC at the ECOC. The chip will be used not only for a particular industry but also for many of next-generation, super-high-speed information communications technologies, such as high-speed USB, high-definition multimedia interface (HDMI), and TV interface.”
Before joining KAIST, Hyeon-Min Bae worked for many years at Finisar as a researcher who designed and developed the world’s first super-high-speed circuit, the 100 Gbps Ethernet IC.
2013.11.25 View 9756 -
Observation of a water strider led to a new method of measuring properties of Nano films
Even the mechanical properties of Nano films of a few nanometers thick can be measured
Posted online Nature Communications on the 3rd of October
The joint research team of KAIST’s Department of Mechanical Engineering’s Professor Taek-Soo Kim and Doctor Seung-Min Hyun of the Nano mechanics laboratory of Korea Institute of Machinery and Materials has developed a new method to evaluate mechanical properties of Nano films using the characteristics of water surfaces.
The research findings have been posted on the online edition of Nature Communications on the 3rd of October. The technology can obtain accurate results by directly measuring the mechanical properties such as the strength and elasticity of Nano films. Academia and the industry expect the simplicity of the technology to present a new paradigm in the evaluation of mechanical properties of Nano films.
Evaluation of the mechanical properties of Nano films is essential not only in predicting the reliability of semiconductors and displays, but also in finding new phenomena in the Nano world. However, mechanical strength was difficult to test since the test demands the falling of objects to the ground to measure their strength, and nano films can easily break in the process.
The research team observed insects such as water striders freely floating on the surface of the water. The team used the properties of water, large surface tension and low viscosity, to float a 55 nanometers (nm) gold Nano film to successfully measure its mechanical properties without damaging it. The technology could be used to measure the mechanical properties of not only various types of Nano films but also films only a few nm thick.
Professor Taek-Soo Kim said, “We effectively performed an evaluation of the mechanical characteristics of Nano films, which was difficult in the past, by developing a new strength test using the properties of water.” He continued to say, “The team plans to discover the mechanical properties of 2D Nano films such as graphene that could not have been measured with the existing strength test methods.”
The research by KAIST’s Department of Mechanical Engineering’s graduate student Jae-Han Kim (lead author) under the supervision of Professor Taek-Soo Kim and Doctor Seung-Min Hyun of Korea Institute of Machinery and Materials was sponsored by the National Research Foundation of Korea.
Evaluation process of mechanical properties of Nano films by using the characteristics of water surfaces
Dr Seung-Min Hyun, Jae-Han Kim, and Professor Taek-Soo Kim from left to right
2013.11.11 View 9124 -
Metabolically engineered E. coli producing phenol
Many chemicals we use in everyday life are derived from fossil resources. Due to the increasing concerns on the use of fossil resources, there has been much interest in producing chemicals from renewable resources through biotechnology.
Phenol is an important commodity chemical, and is a starting material for the production of numerous industrial chemicals and polymers, including bisphenol A and phenolic resins, and others. At present, the production of phenol entirely depends on the chemical synthesis from benzene, and its annual production exceeds 8 million tons worldwide. Microbial production of phenol seems to be a non-viable process considering the high toxicity of phenol to the cell.
In the paper published online in Biotechnology Journal, a Korean research team led by Distinguished Professor Sang Yup Lee at the Department of Chemical and Biomolecular Engineering from the Korea Advanced Institute of Science and Technology (KAIST) reported the successful development of an engineered Escherichia coli (E. coli) strain which can produce phenol from glucose. E. coli has been a workhorse for biological production of various value-added compounds such as succinic acid and 1,4-butanediol in industrial scale. However, due to its low tolerance to phenol, E. coli was not considered a viable host strain for the biological production of phenol.
Professor Lee"s team, a leading research group in metabolic engineering, noted the genetic and physiological differences of various E. coli strains and investigated 18 different E. coli strains with respect to phenol tolerance and engineered all of the 18 strains simultaneously. If the traditional genetic engineering methods were used, this work would have taken years to do. To overcome this challenge, the research team used synthetic small RNA (sRNA) technology they recently developed (Nature Biotechnology, vol 31, pp 170-174, 2013). The sRNA technology allowed the team to screen 18 E. coli strains with respect to the phenol tolerance, and the activities of the metabolic pathway and enzyme involved in the production of phenol. The research team also metabolically engineered the E. coli strains to increase carbon flux toward phenol and finally generated an engineered E. coli strain which can produce phenol from glucose.
Furthermore, the team developed a biphasic extractive fermentation process to minimize the toxicity of phenol to E. coli cells. Glycerol tributyrate was found to have low toxicity to E. coli and allowed efficient extraction of phenol from the culture broth. Through the biphasic fed-batch fermentation using glycerol tributyrate as an in situ extractant, the final engineered E. coli strain produced phenol to the highest titer and productivity reported (3.8 g/L and 0.18 g/L/h, respectively). The strategy used for the strain development and the fermentation process will serve as a framework for metabolic engineering of microorganisms for the production of toxic chemicals from renewable resources.
This work was supported by the Intelligent Synthetic Biology Center through the Global Frontier Project (2011-0031963) of the Ministry of Science, ICT & Future Planning through the National Research Foundation of Korea.
Process of Phenol Production
2013.11.05 View 10629 -
KAIST announced a novel technology to produce gasoline by a metabolically engineered microorganism
A major scientific breakthrough in the development of renewable energy sources and other important chemicals; The research team succeeded in producing 580 mg of gasoline per liter of cultured broth by converting in vivo generated fatty acids
For many decades, we have been relying on fossil resources to produce liquid fuels such as gasoline, diesel, and many industrial and consumer chemicals for daily use. However, increasing strains on natural resources as well as environmental issues including global warming have triggered a strong interest in developing sustainable ways to obtain fuels and chemicals.
Gasoline, the petroleum-derived product that is most widely used as a fuel for transportation, is a mixture of hydrocarbons, additives, and blending agents. The hydrocarbons, called alkanes, consist only of carbon and hydrogen atoms. Gasoline has a combination of straight-chain and branched-chain alkanes (hydrocarbons) consisted of 4-12 carbon atoms linked by direct carbon-carbon bonds.
Previously, through metabolic engineering of Escherichia coli (E. coli), there have been a few research results on the production of long-chain alkanes, which consist of 13-17 carbon atoms, suitable for replacing diesel. However, there has been no report on the microbial production of short-chain alkanes, a possible substitute for gasoline.
In the paper (entitled "Microbial Production of Short-chain Alkanes") published online in Nature on September 29, a Korean research team led by Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering at the Korea Advanced Institute of Science and Technology (KAIST) reported, for the first time, the development of a novel strategy for microbial gasoline production through metabolic engineering of E. coli.
The research team engineered the fatty acid metabolism to provide the fatty acid derivatives that are shorter than normal intracellular fatty acid metabolites, and introduced a novel synthetic pathway for the biosynthesis of short-chain alkanes. This allowed the development of platform E. coli strain capable of producing gasoline for the first time. Furthermore, this platform strain, if desired, can be modified to produce other products such as short-chain fatty esters and short-chain fatty alcohols.
In this paper, the Korean researchers described detailed strategies for 1) screening of enzymes associated with the production of fatty acids, 2) engineering of enzymes and fatty acid biosynthetic pathways to concentrate carbon flux towards the short-chain fatty acid production, and 3) converting short-chain fatty acids to their corresponding alkanes (gasoline) by introducing a novel synthetic pathway and optimization of culture conditions. Furthermore, the research team showed the possibility of producing fatty esters and alcohols by introducing responsible enzymes into the same platform strain.
Professor Sang Yup Lee said, "It is only the beginning of the work towards sustainable production of gasoline. The titer is rather low due to the low metabolic flux towards the formation of short-chain fatty acids and their derivatives. We are currently working on increasing the titer, yield and productivity of bio-gasoline. Nonetheless, we are pleased to report, for the first time, the production of gasoline through the metabolic engineering of E. coli, which we hope will serve as a basis for the metabolic engineering of microorganisms to produce fuels and chemicals from renewable resources."
This research was supported by the Advanced Biomass Research and Development Center of Korea (ABC-2010-0029799) through the Global Frontier Research Program of the Ministry of Science, ICT and Future Planning (MSIP) through the National Research Foundation (NRF), Republic of Korea. Systems metabolic engineering work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries (NRF-2012-C1AAA001-2012M1A2A2026556) by MSIP through NRF.
Short-Chain Alkanes Generated from Renewable Biomass
This diagram shows the metabolic engineering of Escherichia coli for the production of short-chain alkanes (gasoline) from renewable biomass.
Nature Cover Page (September 29th, 2013)
2013.11.04 View 12569 -
A powerful strategy for developing microbial cell factories by employing synthetic small RNAs
The current systems for the production of chemicals, fuels and materials heavily rely on the use of fossil resources. Due to the increasing concerns on climate change and other environmental problems, however, there has been much interest in developing biorefineries for the production of such chemicals, fuels and materials from renewable resources. For the biorefineries to be competitive with the traditional fossil resource-based refineries, development of high performance microorganisms is the most important as it will affect the overall economics of the process most significantly. Metabolic engineering, which can be defined as purposeful modification of cellular metabolic and regulatory networks with an aim to improve the production of a desired product, has been successfully employed to improve the performance of the cell. However, it is not trivial to engineer the cellular metabolism and regulatory circuits in the cell due to their high complexity.
In metabolic engineering, it is important to find the genes that need to be amplified and attenuated in order to increase the product formation rate while minimizing the production of undesirable byproducts. Gene knock-out experiments are often performed to delete those metabolic fluxes that will consequently result in the increase of the desired product formation. However, gene knock-out experiments require much effort and time to perform, and are difficult to do for a large number of genes. Furthermore, the gene knock-out experiments performed in one strain cannot be transferred to another organism and thus the whole experimental process has to be repeated. This is a big problem in developing a high performance microbial cell factory because it is required to find the best platform strain among many different strains. Therefore, researchers have been eager to develop a strategy that allows rapid identification of multiple genes to be attenuated in multiple strains at the same time.
A Korean research team led by Distinguished Professor Sang Yup Lee at the Department of Chemical and Biomolecular Engineering from the Korea Advanced Institute of Science and Technology (KAIST) reported the development of a strategy for efficiently developing microbial cell factories by employing synthetic small RNAs (sRNAs). They first reported the development of such system in Nature Biotechnology last February. This strategy of employing synthetic sRNAs in metabolic engineering has been receiving great interest worldwide as it allows easy, rapid, high-throughput, tunable, and un-doable knock-down of multiple genes in multiple strains at the same time. The research team published a paper online on August 8 as a cover page (September issue) in Nature Protocols, describing the detailed strategy and protocol to employ synthetic sRNAs for metabolic engineering.
In this paper, researchers described the detailed step-by-step protocol for synthetic sRNA-based gene expression control, including the sRNA design principles. Tailor-made synthetic sRNAs can be easily manipulated by using conventional gene cloning method. The use of synthetic sRNAs for gene expression regulation provides several advantages such as portability, conditionality, and tunability in high-throughput experiments. Plasmid-based synthetic sRNA expression system does not leave any scar on the chromosome, and can be easily transferred to many other host strains to be examined. Thus, the construction of libraries and examination of different host strains are much easier than the conventional hard-coded gene manipulation systems. Also, the expression of genes can be conditionally repressed by controlling the production of synthetic sRNAs. Synthetic sRNAs possessing different repression efficiencies make it possible to finely tune the gene expression levels as well. Furthermore, synthetic sRNAs allow knock-down of the expression of essential genes, which was not possible by conventional gene knock-out experiments.
Synthetic sRNAs can be utilized for diverse experiments where gene expression regulation is needed. One of promising applications is high-throughput screening of the target genes to be manipulated and multiple strains simultaneously to enhance the production of chemicals and materials of interest. Such simultaneous optimization of gene targets and strains has been one of the big challenges in metabolic engineering. Another application is to fine tune the expression of the screened genes for flux optimization, which would enhance chemical production further by balancing the flux between biomass formation and target chemical production. Synthetic sRNAs can also be applied to finely regulating genetic interactions in a circuit or network, which is essential in synthetic biology. Once a sRNA scaffold-harboring plasmid is constructed, tailor-made, synthetic sRNAs can be made within 3-4 days, followed by the desired application experiments.
Dr. Eytan Zlotorynski, an editor at Nature Protocols, said "This paper describes the detailed protocol for the design and applications of synthetic sRNA. The method, which has many advantages, is likely to become common practice, and prove useful for metabolic engineering and synthetic biology studies."
This paper published in Nature Protocols will be useful for all researchers in academia and industry who are interested in the use of synthetic sRNAs for fundamental and applied biological and biotechnological studies.
This work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries (NRF-2012-C1AAA001-2012M1A2A2026556) and the Intelligent Synthetic Biology Center through the Global Frontier Project (2011-0031963) of the Ministry of Science, ICT and Future Planning through the National Research Foundation of Korea.
2013.10.31 View 10105 -
Core Technology for Lithium Air Secondary Battery Developed
KAIST-Kyonggi University joint research team developed composite catalyst out of nano fiber and graphene
Five times improvement in capacity compared to lithium-ion secondary battery, driving 800 km at maximum
The core technology for lithium air secondary battery, the next generation high capacity battery, has been developed.
A research team formed by KAIST Department of Materials Science’s Professors Il-Doo Kim and Seokwoo Jeon, and Kyonggi University Department of Materials Science’s Professor Yong-Joon Park has created a lithium air secondary battery, with five times greater storage than the lithium-ion secondary battery, by developing a nano fiber-graphene composite catalyst. The research results are published in the August 8th online edition of Nano Letters.
A cathode of a lithium-ion battery consists of graphite and an anode of the battery consists of a lithium transition metal oxide. Lithium-ion batteries are widely used in mobile phones and laptops. However, lithium-ion batteries cannot support electric vehicles, providing energy for only 160 kilometers on one full charge. The lithium air secondary battery just developed by the research team uses lithium on the cathode and oxygen on the anode. It is earning a popular acknowledgement among the next generation secondary battery research community for having lightweight mass and high energy density.
However, lithium-ion batteries remain difficult to commercialize because of their short lifespan. Lithium and oxygen meet up to form lithium oxide (Li2O2) at discharge, and decompose again at charge. In a traditional lithium air battery, this cycle does not occur smoothly and results in high resistance, thereby reducing the lifespan of the battery. It is thus essential to develop high efficiency catalyst that facilitates the formation and decomposition of lithium oxides.
The research team used electric radiation to develop a nano composite catalyst by mixing cobalt oxide nano fiber and graphene. The performance of the battery has been maximized by settling nonoxidative graphene, which has high specific surface area and electrical conductivity, on catalyst active cobalt oxide nano fiber. Applying the nano composite catalyst on both poles of the lithium air battery resulted in an improved lifespan of over 80 recharge cycles with capacity greater than 100mAh/g, five times greater than a lithium ion battery. The newly discovered charge-discharge property is the highest among the reported performances of the lithium air battery so far.
The lithium air battery is cheap to make, as the main materials are metal oxide and graphene. “There are yet more issues to resolve such as stability, but we will collaborate with other organizations to open up the era of electronic vehicles,” said Professor Il-Doo Kim. “We hope to contribute to vitalizing the fields of next generation lithium air battery by leading nanocatalyst synthesis technology, one of the core materials in the fields of secondary battery,” Professor Kim spoke of his aspiration.
The graduate students participated in the research are Won-Hee Ryu, a postdoctorate at KAIST Department of Materials Science, Sungho Song, a PhD candidate at KAIST Department of Materials Science, and Taek-Han Yoon, a graduate student at Kyonggi University.
Picture I: Schematic Diagram of Lithium Air Battery Made of Nano Composite Catalysts
Picture II: Images of Cobalt Oxide Nano Fibers and Graphene Nano Composite Catalysts
Picture III: Images of Manufacturing Process of Cobalt Oxide Nano Fibers and Graphene Nano Composite Catalysts for Lithium Air Battery
2013.10.18 View 12366 -
Nanowire Made of Diverse Materials May Become Marketable
- Technology to commercialize nanowire developed after 2 years of industrial-academic joint research -
- 2 million strands of 50nm-width, 20 cm-length nanowire mass producible in 2 hours –
A South Korean joint industrial-academic research team has developed the technology to put forward the commercialization of nanowire that is only a few nanometers wide. It is expected to be applied in various fields such as semiconductors, high performance sensors, and biodevices.
In cooperation with LG Innotek and the National Nanofab center, Professor Jun-Bo Yoon, from KAIST Department of Electrical Engineering, developed the technology to mass produce nanowire at any length with various materials. The research results are published on the online edition of Nano Letters on July 30th.
Nanowire has a long linear structure with its width at 100 nanometers at maximum. It is a multifunctional material that has yet undiscovered thermal, electric, and mechanical properties. Nanowire is highly acclaimed as a cutting-edge material with unique nano-level properties that can be applied in semiconductors, energy, biodevices, and optic devices.
Previously, nanowires had an extremely low synthesis rate that required three or four days to grow few millimeters. It was therefore difficult to produce the desired products using nanowires. Moreover, nanowires needed to be evenly arranged for practical application, but the traditional technology required complex post-treatment, not to mention the arrangement was not immaculate.
The research team applied semiconductor process instead of chemical synthesis to resolve these issues. The team first formed a pattern greater that of the target frequency by using a photo-engraving process on a silicon wafer board whose diameter was 20 centimeters, then repeatedly reduced the frequency to produce 100 nm ultrafine linear grid pattern. Based on this pattern, the research team applied the sputtering process to mass-produce nanowires in perfect shapes of 50 nm width and 20 cm maximum length.
The new technology requires neither a lengthy synthesis process nor post-cleaning to attain a perfectly aligned state. Thus, academic and industrial circles consider the technology has high possibilities for commercialization.
“The significance is in resolving the issues in traditional technology, such as low productivity, long manufacturing time, restrictions in material synthesis, and nanowire alignment,” commented Professor Yoon on this research. “Nanowires have not been widely applied in the industry, but this technology will bring forward the commercialization of high performance semiconductors, optic devices, and biodevices that make use of nanowires.”
2013.10.18 View 9795 -
Prof. Jiyun Lee receives the U.S. FAA Achievement Award
- Ensures the safe operation of aircraft by monitoring ionospheric changes caused by solar storms.
KAIST’s Aerospace Engineering Department’s Professor Jiyun Lee has received an award from the U.S. Federal Aviation Administration (FAA), in recognition of her work for developing a Global Positioning System (GPS) reinforcing system and improving Satellite Navigation technology.
A GPS reinforcing system provides real-time GPS location and integrity information within 1m ranges to enable the accurate and safe navigation of aircraft. However, when the sun reaches Solar Max, the amount of total electron increases rapidly in the ionosphere. This also increases the possibility of the position error of navigation using the GPS reinforcing system. In order to solve this problem, Professor Lee built an Ionosphere Danger model that monitors the changes in the ionosphere due to solar storm. The model has been implemented into original monitoring software that secures the safety of the GPS reinforcing system user. The research results were published in July 2012 in Radio Science, one of the most prestigious international journals in the field of geophysical studies.
The FAA Technical Center successfully verified Professor Lee’s software and the software is currently being distributed and used by major institutions around the globe, including Eurocontrol. It is expected that the software will be standardized after consultations with international organizations in the recent future.
Professor Lee said, “Satellite navigation is the core of future navigation technology. Since its utilization has been extended to aviation, marine, transportation, telecommunications, finance and other major national infrastructures, it is crucial to ensure the performance and reliability of the system … In the future, cooperation between nations will help to develop the worldwide service of the GPS reinforcing system.”
2013.10.12 View 9615