research
-
Method to Synthesize New Lithium Ion Battery Cathode Material Identified
A KAIST research team headed by Prof. Do-Kyung Kim at the Department of Materials Science and Engineering developed a technology to synthesize a new lithium ion battery spinel cathode which is regarded as a core part of hybrid and lithium battery cars.
The research was conducted in collaboration with a research team of Prof. Yi Cui at Stanford University"s Department of Chemistry. Their findings were introduced in the November issue of Nano Letters, one of the leading academic journals in nano-science.
The newly synthesized lithium ion battery spinel cathode known as spinel LiMn2O4 nanorods is attracting interests as an alternative cathode material since it is a low-cost, environmentally friendly substance for Li-ion battery cathodes. Its raw material is also highly available.
Lithium ion batteries with high energy and power density are important for consumer electronic devices, portable power tools, and vehicle electrification. LixCoO2 is a commonly used cathode material in commercial lithium iron batteries. However, the high cost, toxicity, and limited abundance of cobalt have been recognized to be disadvantageous.
2008.11.20 View 13012 -
KAIST Research Team Unveils Method to Fabricate Photonic Janus Balls
A research team led by Prof. Seung-Man Yang of the Department of Chemical and Biomolecular Engineering has found a method to fabricate photonic Janus balls with isotropic structural colors.
The finding draws attention since the newly-fabricated photonic balls may prove useful pigments for the realization of e-paper or flexible electronic displays.
The breakthrough was published in the Nov. 3 edition of the science journal "Advanced Materials." The Nov. 6 issue of "Nature" also featured it as one of the research highlights under the title of "Future Pixels."
Prof. Yang"s research team found that tiny marbles, black on one side and colored on the other, can be made by "curing" suspensions of silica particles with an ultraviolet lamp. When an electric field is applied, the marbles line up so that the black sides all face upwards, which suggests they may prove useful pigments for flexible electronic displays.
The researchers suspended a flow of carbon-black particles mixed with silica and a transparent or colored silica flow in a resin that polymerizes under ultraviolet light. They then passed the mixture through a tiny see-through tube. The light solidified the silica and resin as balls with differently colored regions, each about 200 micrometers in diameter.
Over the last decades, the development of industrial platforms to artificially fabricate structural color pigments has been a pressing issue in the research areas of materials science and optics. Prof. Yang, who is also the director of the National Creative Research Initiative Center for Integrated Optofluidic Systems, has led the researches focused on fabrication of functional nano-materials through the process of assembling nano-building blocks into designed patterns.
The "complementary hybridization of optical and fluidic devices for integrated optofluidic systems" research was supported by a grant from the Creative Research Initiative Program of the Ministry of Education, Science & Technology.
2008.11.12 View 14455 -
KAIST Team Identifies Nano-scale Origin of Toughness in Rare Earth-added Silicon Carbide
A research team led by Prof. Do-Kyung Kim of the Department of Materials Science and Engineering of KAIST has identified the nano-scale origin of the toughness in rare-earth doped silicon carbide (RE-SiC), university sources said on Monday (Oct. 6).
The research was conducted jointly with a U.S. team headed by Prof. R. O. Ritchie of the Department of Materials Science and Engineering, University of California, Berkeley.
The findings were carried in the online edition of Nano Letters published by the American Chemical Association.
Silicon carbide, a ceramic material known to be one of the hardest substances, are potential candidate materials for many ultrahigh-temperature structural applications. For example, if SiC, instead of metallic alloys, is used in gas-turbine engines for power generation and aerospace applications, operating temperatures of many hundred degrees higher can be obtained with a consequent dramatic increase in thermodynamic efficiency and reduced fuel consumption. However, the use of such ceramic materials has so far been severely limited since the origin of the toughness in RE-SiC remained unknown thus far.
In order to investigate the origin of the toughness in RE-SiC, the researchers attempted to examine the mechanistic nature of the cracking events, which they found to occur precisely along the interface between SiC grains and the nano-scale grain-boundary phase, by using ultrahigh-resolution transmission electron microscopy and atomic-scale spectroscopy. The research found that for optimal toughness, the relative elastic modulus across the grain-boundary phase and the interfacial fracture toughness are the most critical material parameters; both can be altered with appropriate choice of rare-earth elements.
In addition to identifying the nano-scale origin of the toughness in RE-SiC, the findings also contributed to precisely predicting how the use of various rare-earth elements lead to difference in toughness.
University sources said that the findings will significantly advance the date when RE-SiC will replace metallic alloys in gas-turbine engines for power generation and aerospace applications.
2008.10.08 View 15475 -
KAIST Professor Exposes Structural Dynamics of Protein in Solution
-- Dr. Hyot-Cherl Ihee"s 3-Year Research Is Valuable in Pharmaceutical Application
Prof. Hyot-Cherl Ihee and his team at the Department of Chemistry, KAIST, has successfully unveiled the structural dynamics of protein in solution as a result of more than three years" research work.
Nature Methods, a sister publication of the authoritative science magazine Nature, published the treatise, titled "Tracking the structural dynamics of proteins in solution using time-resolved wide-angle X-ray scattering" in its Sept. 22 online edition. The research paper will be carried in the magazine"s printed version in its October edition, according to Dr. Lee who is its correspondence author.
In May 2005, Prof. Ihee successfully photographed the structural dynamics of protein in solid state and his findings were published in the Proceedings of National Academy of Science of the United States. As protein normally exists in human body in solution, not in solid state, he directed his research to developing the technology to capture protein"s dynamics in resolved state.
In July that year, Prof. Ihee succeeded in measuring the structural changes of simple organic molecules in real time. He further developed the technology to uncover the structural dynamics of hemoglobin, myoglobin and cytochrome C.
Prof. Ihee"s research, helped with the Education-Science-Technology Ministry"s Creative Research Promotion Fund, can be applied to new pharmaceutical development projects as well as nanotechnology development, according to KAIST officials.
Prof. Ihee who earned his doctorate at California Institute of Technology in 1994 began teaching at KAIST in 2003. He won the Young Scientist Award given by the Korean government in 2006.
2008.09.22 View 13828 -
KAIST Professor Finds Paradox in Human Behaviors on Road
-Strange as it might seem, closing roads can cut delays
A new route opened to ease traffic jam, but commuting time has not been reduced.Conversely, motorists reached their destinations in shorter times after a big street was closed. These paradoxical phenomena are the result of human selfishness, according to recent findings of a research team led by a KAIST physics professor.
Prof. Ha-Woong Jeong, 40, at the Department of Physics, conducted a joint research with a team from Santa Fe Institute of the U.S. to analyze the behaviors of drivers in Boston, New York and London. Their study found that when individual drivers, fed with traffic information via various kinds of media, try to choose the quickest route, it can cause delays for others and even worsen congestion.
Prof. Jeong and his group"s study will be published in the Sept. 18 edition of the authoritative Physical Review Letters. The London-based Economist magazine introduced Prof. Jeong"s finding in its latest edition.
Prof. Jeong, a pioneer in the study of "complex system," has published more than 70 research papers in the world"s leading science journals, including Nature, PNAS and Physical Review Letters. "Initially, my study was to reduce annoyance from traffic jam during rush hours," Prof. Jeong said. "Ultimately, it is purposed to eliminate inefficiency located in various corners of social activities, with the help of the network science."
The Economist article read (in part):
"...when individual drivers each try to choose the quickest route it can cause delays for others and even increase hold-ups in the entire road network.
"The physicists give a simplified example of how this can happen: trying to reach a destination either by using a short but narrow bridge or a longer but wide motorway. In their hypothetical case, the combined travel time of all the drivers is minimized if half use the bridge and half the motorway. But that is not what happens. Some drivers will switch to the bridge to shorten their commute, but as the traffic builds up there the motorway starts to look like a better bet, so some switch back. Eventually the traffic flow on the two routes settles into what game theory calls a Nash equilibrium, named after John Nash, the mathematician who described it. This is the point where no individual driver could arrive any faster by switching routes.
"The researchers looked at how this equilibrium could arise if travelling across Boston from Harvard Square to Boston Common. They analysed 246 different links in the road network that could be used for the journey and calculated traffic flows at different volumes to produce what they call a “price of anarchy” (POA). This is the ratio of the total cost of the Nash equilibrium to the total cost of an optimal traffic flow directed by an omniscient traffic controller. In Boston they found that at high traffic levels drivers face a POA which results in journey times 30% longer than if motorists were co-ordinated into an optimal traffic flow. Much the same thing was found in London (a POA of up to 24% for journeys between Borough and Farringdon Underground stations) and New York (a POA of up to 28% from Washington Market Park to Queens Midtown Tunnel).
"Modifying the road network could reduce delays. And contrary to popular belief, a simple way to do that might be to close certain roads. This is known as Braess’s paradox, after another mathematician, Dietrich Braess, who found that adding extra capacity to a network can sometimes reduce its overall efficiency.
"In Boston the group looked to see if the paradox could be created by closing any of the 246 links. In 240 cases their analysis showed that a closure increased traffic problems. But closing any one of the remaining six streets reduced the POA of the new Nash equilibrium. Much the same thing was found in London and New York. More work needs to be done to understand these effects, say the researchers. But even so, planners should note that there is now evidence that even a well intentioned new road may make traffic jams worse."
2008.09.18 View 14473 -
Home-Grown Transparent Thin Film Transistor Developed
KAIST, Aug. 6, 2008 -- A KAIST research team led by Profs. Jae-Woo Park and Seung-Hyup Yoo of the Electrical Engineering Division has developed a home-grown technology to create transparent thin film transistor using titanium dioxide., university authorities said.The KAIST team made the technological advance in collaboration with the LCD Division of Samsung Electronics and the Techno Semichem Co., a local LCD equipment maker. Transparent thin film transistor continues to enjoy a wealth of popularity and intensive research interest since it is used in producing operating circuits including transparent display, active-matrix OLED (AMOLED) display and flexible display.
The new technology is significant in that it is based on a titanium dioxide, the first such attempt in the world, while the technologies patented by the United States and Japan are based on ZnO.
Researchers will continue to work on securing technological reliability and developing a technology to mass-produce in a large-scale chemical vapor deposition equipment for the next couple of years.
"The development of technology to produce transparent thin film transistor will help Korean LCD makers reduce its dependence on foreign technologies, as well as maintain Korea"s status as a leader of the world"s display industry," said Prof. Park.
KAIST has applied for local patent registration of the technology and the process is expected to complete by this October or November. International patents have been also applied for in the U.S., Japan and Europe.
The new technology was introduced in the latest edition of the Electron Device Letters, a journal published by the Institute of Electrical and Electronics Engineers or IEEE, a New York-based international non-profit, professional organization for the advancement of technology related to electricity. It will be presented at the International Display Workshop 2008 on Dec. 5 in Niigata, Japan.
2008.08.07 View 15706 -
Storing Stably Hydrogen Atoms in Icy Materials Discovered
KAIST, Aug. 8, 2008 -- A KAIST research team led by Prof. Huen Lee of the Department of Chemical & Biomolecular Engineering has discovered that icy organic hydrates, which contain small cages that can trap guest molecules, can be used to create and trap hydrogen atoms at higher temperatures.
The properties and reactions of single hydrogen atoms are of great scientific interest because of their inherent quantum mechanical behavior; experimentally, they can be generated and stabilized at very low temperatures (4 K) by high-energy irradiation of solid molecular hydrogen.
The finding was reported in the journal of American Chemical Society and featured in the "Editor"s Choice" in the July 11 issue of Science as a recent research highlight.
Hydrogen is a clean and sustainable form of energy that can be used in mobile and stationary applications. Hydrogen has the potential to solve several major challenges today: depletion of fossil fuels, poor air quality, and green house gas emissions.
However, the trapping of hydrogen atoms in crystalline solid matrix has never been attempted mainly because of experimental difficulties in identifying the generated hydrogen atoms with either spectroscopic or microscopic technique.
"To overcome the barriers and limitations of the existing storage approaches, we have continuously attempted to find the new hydrogen storage media such as icy powders and other related inclusion compounds," said Prof. Lee
The discovery follows the breakthrough concept Prof. Lee"s research team proposed in Nature in 2005 to use pure ice to capture and store hydrogen molecules. At moderate temperature and pressure conditions small guest molecules are entrapped in pure ice powders to form the mixed icy hydrate materials.
"Stable existence of single hydrogen molecule/radical in icy crystalline matrices may offer significant advantages in exploring hydrogen as a quantum medium because icy hydrogen hydrates can be formed at milder conditions when compared with pure solid hydrogen, which requires the ultra low temperature of 4.2 K," said Prof. Lee.
The novel design and synthesis of ionic and radicalized icy hydrates are expected to open a new field for inclusion chemistry and ice-based science and technology. Specifically, the fact that hydrogen atoms can be stably stored in icy materials might provide versatile and practical applications to energy devices including fuel cells, ice-induced reactions, and novel energy storage process, according to the KAIST professor.
2008.08.07 View 13824 -
KAIST Professors Article Featured as Cover Thesis of Biotechnology Journal
An article authored by a research team of Prof. Sang-yup Lee at the Department of Chemical and Biomolecular Engineering and Dr. Jin-Hwan Park at the KAIST Institute for the BioCentury has been featured as the cover thesis of the August 2008 issue of Trends in Biotechnology.
The paper, titled "General strategy for strain improvement by means of systems metabolic engineering," focuses on the application of systems biology for the development of strains and illustrates future prospects. Trends in Biotechnology, published by Cell Press, is one of the most prestigious review journals in the field.
Jin-Hwan Park, the primary author of the research thesis, said that the KAIST team"s research work was expected to provide substantial help to researchers involved in biotechnology industry.
The strategy has been established on the basis of the experiences gained in the actual microbial production process using the systems biology methods which his research team has recently worked on, Prof. Park said.
2008.07.24 View 15588 -
Super-Fast Internet Data Chip Developed
A KAIST research team led by Prof. Kyoung-Hoon Yang of the Electrical Engineering & Computer Science Department developed a super-fast chip that could lead to huge advancements in broadband Internet technology, the Korean Ministry of Education, Science and Technology said on Thursday (June 26).
The multiplexer chip is the first of its kind to be developed using the quantum effect of resonant tunnelling diode, according to the Ministry.
The integrated circuit chip built at the university laboratory has an operating speed of 45 gigabits per second (Gb/s), while using roughly 75 percent less energy than the previous version. The speed enables the transfer of about 4 full-length movies in one second.
The best operational broadband Internet services provide users with data transfer speed of 40 Gb/s, while most other high-speed online connections offer 10 Gb/s.
"Besides speed, the greatest achievement is low energy use," Prof. Yang said. He stressed that energy use in chips is a crucial factor because power creates heat that can melt circuits and make them inoperable.
"By cutting down on energy use, the new chips can be made smaller and with faster data transfer speed," the scientist said.
He added that efforts are underway to increase operational speed to 100 Gb/s, with energy consumption to be cut to 10 percent of current chips like the high electron mobility transistor, the heterojunction bipolar transistor and the complementary metal oxide semiconductor.
The researcher speculated that such revolutionary chips could be developed in 1-2 years and become the new benchmark in this field since existing chips have limited development capabilities.
The project has received funding from the Education-Science-Technology Ministry since 2000. The Ministry"s financial support will last until 2010.
2008.06.26 View 13311 -
New System to Generate Extreme-Ultraviolet Light Developed
A KAIST research team led by Prof. Seung-Woo Kim of the Mechanical Engineering Department developed a new system for generating coherent extreme-ultraviolet (EUV) light, school authorities announced on June 5.
The new system comes in a metallic nano-structure consisting of a two-dimensional array of gold "bow tie" elements on a sapphire plate. The new process was featured in the British journal Nature on June 5.
The properties of coherent EUV light make it a prime candidate for exciting technological applications. But, at present, the equipment needed to generate the short-wavelength light is costly and bulky. The system developed by Prof. Kim"s research team is expected to reduce both cost and bulk.
The new system uses the conventional principle of high-harmonic generation via the interaction of a femtosecond laser pulse with a gas, but adopts the novel concept of amplifying light by way of local plasmon field enhancement, according to the research team.
2008.06.10 View 13793 -
KAIST, GS Caltex Jointly Develop New Bacteria to Produce Biobutanol
KAIST and GS Caltex, Korea"s second-largest refiner, have jointly developed a new strain of bacteria to produce biobutanol, which is regarded as a promising next-generation biofuel, KAIST authorities said on Monday (June 2).
A research team led by Prof. Sang-Yup Lee of the Chemical and Biomolecular Engineering Department and researchers of GS Caltex succeeded in developing an improved strain of bacteria which enables to produce a large amount of biobutanol in the process of fermenting biomass. The research team has applied for international patent for the new technology.
Biomass refers to living and recently dead biological material that can be used as fuel or for industrial production. It usually refers to plant matter grown for use as biofuel, but it also includes plant or animal matter used for production of fibers, chemicals or heat.
In the 1970s and 1980s when scientists began researching the possibilities of alternative fuels, bacteria were used in the process of fermenting biomass. This ABE (acetone, butanol, ethanol) fermentation process yields butanol, acetone, and ethanol in a ratio of 6:3:1, respectively. Acetone produced in this process is not usable.
The newly developed technology to produce biobutanol has an advantage of lowering production cost by eliminating the process to separate acetone from butanol. This has been made possible by improving the bacteria used for the fermentation in metabolic engineering terms, and producing butanol and ethanol only in a ratio of 6:1, while curbing the generation of acetone.
In comparison with bioethanol, also a biofuel mixture which is currently under widespread use in some countries, butanol is more easily transported with gasoline and diesel through pipelines because of its lower tendency to separate from the fuel when contaminated with water. Butanol is also less corrosive than ethanol, another reason its transport through pipeline is preferable.
Global interest in full utilization of biomass and development of other alternative energy including biobutanol has deepened in recent years, as crude oil prices have skyrocketed to record levels and climate changes resulting from the excessive use of fossil fuel have been causing various problems around the world.
2008.06.04 View 12894 -
Research Outputs over Carbon Nanotube by Prof. Choi Selected as Research Highlight by ACS
Research Outputs over Carbon Nanotube by Prof. Choi Selected as Research Highlight by ACS
Research Outputs over Carbon Nanotube by Prof. Choi Selected as Research Highlight by ACS
A research team headed by Seong-Min Choi, a professor of Nuclear and Quantum Engineering, KAIST, has developed technologies to stably disperse carbon nanotube particles in aqueous solutions and organic solvents, essential for industrial applications of carbon nanotube, and discovered the dispersion characteristics of carbon nanotube. The research outputs have been published by ‘Advanced materials’ (19, 929, 2007), the most distinguished journal in Material Science field, and introduced as Research Highlight at the May 7th edition of ‘Heart Cut’ by the American Chemical Society (ACS).
A number of processes for industrial applications of carbon nanotube require the dispersion of carbon nanotube in aqueous solutions or organic solvents, and thus far, surfactant particles or DNAs have been used to disperse carbon nanotube particles. However, they have shortcomings of easy destruction of dispersion. In order to overcome such shortcomings, Prof. Choi’s team produced carbon nanotube particle-dispersed aqueous solutions by using surfactant particles and then polymerized surfactant particles absorbed to the surfaces of carbon nanotube in situ to develop carbon nanotube with hydrophile and safe surfaces. The functional carbon nanotube so obtained shows features of easy dispersion in aqueous solutions and organic solvents even after being processed, such as freeze drying, therefore, is expected to significantly contribute to the development of application technologies of carbon nanotubes. Tae-Hwan Kim and Chang-Woo Doh, both doctoral students, played key roles in the researches carried out under the auspices of the Ministry of Science and Technology (MOST) as a nuclear power R&D project, and the relevant technologies were filed for patent applications.
Figures: Carbon nanotube before polymerization (left), carbon nanotube polymerized with surfactant particles (right)
2007.05.14 View 14112